JPH0738921B2 - Fractional solidification method and equipment used therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for producing a high-purity chemical by washing a mixture of crystals and mother liquor by using a unique method and equipment. . By combining the crystal washing method of the present invention with a crystal operation and a crystal melting operation, a highly efficient partial solidification method can be obtained. Further, a highly efficient crystal purification system can be obtained by combining the crystal washing incubator of the present invention, a certain refrigerator and a certain melter. The crystal operation used for this can be a direct or indirect heat transfer method.

2. Background Art In the chemical industry, crystals obtained by the fractional solidification method are purified by two types of separation methods: (a) backwashing of crystals and (b) centrifugation of mother liquor. These two crystal purification methods are found in the art.

2-A. Backwashing of Crystals In recent years, a considerable number of fractional crystallization methods have been developed. These methods were published in 1967 by Marcelle Decker Incorporated of New York City and edited by M. Tiffe and D'Abrieu Earl Wilcox. It is described in detail in the book. It involves separating the crystals from the mother liquor and washing the crystals by a fractional solidification method, the product purity being determined by how effectively this step was performed.

Column crystallization was considered by PM Arnold and is described in US Pat. No. 2,540,977 (1951). The method is carried out in an apparatus consisting of a freeze zone, a refining zone and a melting zone. Crystals and adhesive liquid are carried from the freezing zone through the refining zone to the melting zone where the molten liquid is formed. The molten liquid fraction is removed as the high melting point product. The remaining fraction is returned to the purification zone as a free liquid for differential countercurrent contact with the crystals. Impurities in the crystals in the form of bonding liquid and residence liquid are transferred to the free liquid and removed from the column as a constituent of the low melting point product. Therefore column crystallization is similar to distillation in packed columns. One of the best industrially successful applications of countercurrent column fractional crystallization is described by Dei El Matsukukei in chapter 16 of the publication "Fractional Solidification". This is the Philipps method.
This method is described by PM Arnold [U.S. Pat.
No. 9 (1951), No. 2540083 (1951), and Reissue Patent No. 24038 (1955)], Jay Shemit (US Patent No. 2617274 (1952) and Reissue Patent No. 23810).
No. (1954)] J. A. Weedman (US Pat. No. 2,854,494 (1958)). In this method, the cooled slurry feed from the scraped surface cooler enters at the top of the purification column. The crystals are forced down by a piston and the impure liquid is removed through a wall filter. The wash liquid made by melting the purified crystals at the bottom of the column is carried countercurrently upwards with respect to the crystals. The wash solution may be pulsed upward. The Schildknecht column crystallizer described in chapter 11 of the publication "Fractional Solidification" uses a spiral placed in a column regulated by two concentric tubes to produce crystals. It is rotated to carry it in the desired direction.

The backwasher used by Colt Industries for desalination of seawater has a screen mounted on a vertical wall and a vertical column. The ice-brine slurry enters the bottom of the vertical column. Ice crystals are carried upward by the flow of brine. In addition, ice crystals are pressed into the porous plug, which moves continuously upwards due to the pressure differential maintained across the plug. Excess brine is drained through a screen located approximately midway between the top and bottom of the column. Wash water is introduced at the top of the column. The rate at which the column descends relative to the rate at which the ice plug rises should be much greater than zero to compensate for the dispersion of the new water-brine interface. Purified ice is removed at the top of the column. A detailed description is given in the United Office of the Sayline Water are and Day Report No. 491, published October 1969.

J.A.Dabrillu Muller has published the TNO method in "Encyclopedia of Chemical Technology," Vol. 7, page 250, edited by Kirk and Otomer, published by Willie Company. In this method, separation is achieved by countercurrent washing combined with repeated crystallization facilitated by bombarding the crystals as they move through the vertical column. Impacting is achieved by spheres bouncing on the sieve plate in the vertical column.

Brody purifiers have been used in industrial operation since 1974 and are available from Nofsinger Corporation of Kansas City, Missouri, USA. Brody purifiers use several rotating spiral ribbon tubular crystallizers, with a recovery zone, a refining zone and a purify (purify) zone.
ing) area and a crystal melting area. Raw material enters the plant at a raw material entry point located between the recovery area and the refining area. The internal stream is continuously cooled under controlled conditions as it flows through the tubes in the recovery area. A portion of the feedstock that is low in product component (and contains most of the impurities) exits the plant as a residue. Crystals of the product material form and settle in their own mother liquor. These crystals are mechanically carried by a low speed spiral ribbon countercurrent to the internal liquid flow towards the refining zone. As the crystals are carried in the mother liquor, which is rich in it,
They continue to grow in size and also increase in purity. After passing through the refining zone, the crystals settle by gravity in the refining zone. Here a heater melts the purified crystals; part of the melt is extracted as product, part is refluxed and countercurrently rises to the bed of crystals in the refining zone. Cooling is achieved by a closed coolant system that flows countercurrent to the process liquid. A small heat input is made without a jacket and without a scraper to prevent uncontrolled crystallization.

2-B. Centrifugation of mother liquor from crystals Commercially available centrifuges can be broadly divided into two types, centrifugal filters and sedimentation centrifuges, each of which further advances and releases a separated solid and liquid phase. It can be divided by the means provided. The cost of a centrifuge depends on the centrifugal force with which it operates. An example is a washing machine used to wash clothes. Centrifuges with great centrifugal forces can be very expensive. The centrifuge used in the chemical industry for crystal refining has a gravity of 2000-1000
It produces twice the centrifugal force and is quite expensive. Details of centrifuges used to separate solid-liquid mixtures are described in 1979.
Published by Matsuglow Hill Company in the year
It is provided by Challes M. Ambler in the fourth and fifth divisions of "Handbook of Separation Technics for Chemical Engineers" edited by P.A. -It is also provided by A.C. Lavanchi and others in "Encyclopedia Dia of Chemical Technology," Vol.

2-Ba. Centrifugal Filters Centrifugal filters support a granular solid phase on a porous partition that allows the liquid phase to pass freely under the action of centrifugal force. An important parameter is the permeability of the filter cake under the applied centrifugal force. Except for very specific applications, they are generally only used for dehydration of relatively free-draining solids. Raw slurry concentration and particle size distribution are important factors in centrifugal filter performance. The performance of the centrifuge operation is measured by the amount of mother liquor retained on the drained cake and is expressed by the S value, which is defined as the volume of mother liquor retained per volume of solids. The S value after centrifugation for a certain period of time decreases as the centrifugal force increases. Therefore, in a normal centrifugal filter, a high centrifugal force is applied to obtain a small S value, which reduces the amount of mother liquor retained in the drained cake. Such centrifuges are expensive. The crystals on the centrifugal filter can be washed with a washing solution. The efficiency of washing on a centrifugal filter is usually rather poor because the residence time of the wash liquor is short and the cake on the filter is not properly agitated.

2-Bb. Sedimentation Centrifuge A sedimentation type centrifuge increases gravity with a commercially available factor 2-5 times larger. As in the field of gravity, there must be a difference between the density of the dispersed particles and the density of the liquid phase, which moves the particles away from the axis of rotation when the difference is positive and the difference is If it is negative, move it toward the axis of rotation. In a settling centrifuge, the amount of mother liquor contained in the drained cake is a gradual, inverse function of the residence time and the applied centrifugal force. 10 μm ~ 50
Solid-liquid mixtures with particles in the range of 00 μm can be processed.

Continuous solid bowl centrifuges made by Pensalt Chemical Corporation (Shearpress) and Bird Corporation belong to this category. The two main components of the solid bowl centrifuge are the rotating bowl, which is the settling vessel, and the conveyor, which discharges the settled solids. The bowl has an adjustable overflow weir at its large end for discharge of the clarified effluent and a solids outlet at the opposite end for discharging dehydrated solids.

3. Disclosure of the invention It is not possible to reach the theoretical product purity as indicated in phase equilibria due to various causes for purifying chemicals by the currently practiced partial solidification method. .. The mother liquor is often trapped in the incomplete crystals and in the clumps of crystal clusters, causing high purity. Furthermore, the crystals are surrounded by a large amount of mother liquor and are contaminated by surface tension and capillary action. Foreign substances (impurities) are also adsorbed on the crystal surface. Another source of impurities in crystals is solid solubility.

In the text, "Free liquid" means a liquid that can be excreted from the solid bed or can be made into running water, and "Retained liquid" cannot be immediately excreted from the solid bed or cannot pass through it. Represents a liquid. "Crystal space"
(Intercrystalline space) means a space not occupied by crystals. “Free space between crystals” (Intercrystalli
The nefree space is the space between crystals that is not occupied by the retained liquid. So the inter-crystal free space may be completely occupied by free liquid, gas phase or filled with free liquid and gas phase. Simply put, “solid phase”
The solid phase is a solid-liquid mixture that is transported together and is abbreviated as “K-fluid” (K-Stream). The solid phase may be a soft mud (slush), which is determined by the amount of liquid contained in the solid, a wet cake (Wet cake), or a dried cake (drained cake).

This patent application relates to a group of inventions. This group of inventions are linked together to form a single inventive concept. Therefore, there are numerous ways to implement the invention. In the present invention, effective operation of crystal washing requires some basic conditions. There are effective ways of satisfying these conditions, and several methods are combined into each method for carrying out the present invention.

As is known, the crystal bed to be washed is divided into two types depending on whether the inter-crystal free space is completely filled with liquid or not. The former is called a submerged bed and the latter is called a drained bed. Some schemes of the invention are dedicated to the treatment of submerged beds, some are dedicated to the treatment of depleted beds and some are common to both submerged and depleted beds.

The purifying action of the present invention is completed in a purifying section having a front end and a rear end. The solid phase is transported from the front end to the rear end, and the free liquid is transported from the rear end to the front end in the direction opposite to the transport direction of the solid phase. The purification area may consist of several subdivisions and may be one continuous area. When the concentration of contaminants (impurities) in the purification area is drawn in the figure, the concentration of contaminants gradually decreases from the front end to the rear end. At some locations the contaminant concentration in the retained liquid is higher than that in the free liquid. The contaminants in the accumulated liquid area first move to the free liquid area, and then are removed from this area by backwashing or excretion.Usually, the solid after purification is melted and a part of it is first washed. Use as a liquid. Of course,
Other liquids may be used.

In designing the present invention, it was recognized that it is necessary to simultaneously satisfy the following basic conditions in order to obtain an effective cleaning effect. It is difficult to economically obtain high-purity crystals if only some of the basic conditions are satisfied. These basic conditions are listed below.

(a) First condition The retained liquid is a liquid that cannot be easily replaced or excreted from the crystal bed. At some locations, the contaminant concentration in the retained liquid is higher than that in the free liquid near the retained liquid. The foreign matter in the retained liquid diffuses naturally into the free liquid, but at a low speed. Therefore, it is necessary to speed up the transfer rate of accumulated liquid to free liquid. Moreover, this must be achieved in a suitable way that does not interfere with other basic conditions. A method that satisfies this condition is referred to as "a method for transferring a contaminant from a stagnant liquid to a free liquid", and is also abbreviated as a "miscible substance transfer method" or "A-type operation". The A-type operation will be explained in detail later.

There may be an operation in which the first condition called the A-n division and the second condition described below are simultaneously satisfied in the area where the A-type operation is performed. This is called AB type operation. AB type operations are also used where A type operations are performed. The "dust transfer method" therefore includes both A-type and AB-type operations.

(b) Second condition This is a condition that reduces the miscellaneous mass in the free space between crystals. The means for satisfying this condition is referred to as "the inter-crystal free space contaminant reduction method", or simply "the contaminant reduction method",
It is abbreviated as B-type operation. Type B operation is "replacement operation" (disp
lacement operation) or excretion operation (draining operati
on) or compaction operatio
It may be n). The area where the B-type operation is performed is B-
It is called an n-division. The AB-type operation described above is also used for performing B-type operations. Therefore, the "inter-crystal free space contaminant reduction method" includes B-type and AB-type operations.

(c) Third condition When reducing the amount of contaminants from the free liquid of the crystal bed in the displacement operation, the level of channelling can be made extremely low by appropriately hardening the crystal bed. It is important to control. When the A- and B-divisions are installed alternately in the purification tower, it is important to keep the shortness of the B-division low, but it is not so important to control the shortness of the A-division. When the AB section is installed in the purification tower and both A-type and B-type operations are performed at the same time, it is necessary to reduce the short path.

(d) Fourth condition Within the purification zone, the solid phase is transported in the general direction from the front end to the rear end. When the solid phase is transported in the opposite direction, the cleaning effect is reduced. Therefore, Type A operation is confined to a rather narrow area in the transverse and transverse transport directions of the solid phase.

(e) Fifth condition In the purification zone, the concentration of contaminants gradually decreases from the front end toward the rear end, so the free liquid is pushed toward the front end from the rear end as a crystal washing operation. Therefore, displacing the liquid in the opposite direction, that is, from the front end toward the rear end reduces the cleaning effect of the crystals. Since the solid phase is transferred from the front end toward the rear end, the stagnant liquid in the solid phase is transported in the defective direction. To reduce the damage due to this, (1) lower the amount of mother liquor in the transported solid phase, and (2) backwash the solid phase during transportation,
(3) The above two methods can be applied at the same time.

(f) Sixth condition The concentration of contaminants in the crystal backwasher and the temperature are related to the position in the crystal bed, and their relationship can be represented by a diagram. The contaminant concentration gradually decreases from the front end to the rear end, and the temperature rises in the same direction. This is because the crystal formation temperature of the solution rises as the concentration of the impurities decreases. Therefore, the solid phase sequentially encounters a warmer, pure free liquid as it is transported. The crystals in the solid phase are then heated and the heat is obtained from the free liquid. This removal of heat creates a certain amount of crystals from the liquid surrounding the crystals. This phenomenon is called wash-front solidification. When the initial permeability of the crystal bed is too low, the formation of this extra solid greatly reduces the permeability of the crystal bed, making backwashing difficult. In this case,
It is necessary to destroy the crystal bed once or perform a multi-stage washing operation with an increasingly high concentration washing solution.

As described above, the A-type operation and the B-type operation satisfy the first condition and the second condition, respectively. AB type operation is a method that satisfies the first condition and the second condition at the same time without violating the external basic conditions. These three types of operations are explained as follows.

(a) A-type transport operation The A-type operation is a method for increasing the speed at which contaminants are transferred from the retained liquid to the free liquid. However, avoid vertical stirring of the two-phase mixture as much as possible. Type A operations are performed in combination with Type B operations. Backwashing the crystal bed with localized and horizontal agitation (type A operation) or compaction operation (B
When it is carried out together with the mold operation), the lower the M / S ratio, which is represented by the ratio of the mother liquor to the solid in the stirring bed and the M / S ratio. If possible, the M / S ratio should be lower than 2.0: 1 or even lower than 1.5: 1. The M / S ratio need not be higher than 2: 1. If the crystal bed is stirred lightly, it is advisable to operate with an M / S ratio lower than, for example, 1: 1. This method is used in the first mode of carrying out the present invention. Local agitation is achieved by one active arm or axis, or an agitator blade connected to a solid such as a support wall. When dipping or stirring work (A-type operation) is performed in combination with excretion operation to form a dried rice cake (B-type operation), the M / S ratio used for it is not so important and high M / S ratio is also used. Be seen. This method of operation is used in the second mode of practicing the present invention and is described below.

(b) B-type transport operation The B-type transport operation is an operation for reducing miscellaneous mass from the free space between crystals. The B-type transportation operation is accomplished by a backwash operation, a discharge operation, a compression operation, or a combination operation of any of the above.

The A-type operation and the B-type operation are combined to form a common set, and this two-step operation is performed once or twice. This treatment method has multiple stages and is implemented in a purification zone with A- and B-sections on each stage. The A-type operation and the B-type operation are performed in the A-section and the B-section, respectively. A- and B-districts are in different wards, and B-
When a dense bed is formed in the subdivision, the other basic conditions described above are satisfied at the same time.

(c) AB type operation The AB type operation is an operation that satisfies the first condition and the second condition at the same time, and does not disturb the other basic conditions so much. In the text, "AB type operation" is included in the "A type operation" item,
The "AB type operation" is also included in the "B type operation" item. The AB operation is a combination of local agitation and a backwash operation which prevents liquid flow from being channeled excessively. Examples of AB-type operations include: (i) ultrasonic vibration with backwash; (ii) agitation with fine threads or flakes with backwash; (iii) static mixing with backwash. .

In the first method for carrying out the present invention, a crystal washing operation (agitated crystal) by local agitation with a washing liquid is performed in the purification zone.
washing) and stereotactic crystal washing operations (stationary crystal
washing) alternately, the solid phase and the free liquid are moved in opposite directions to purify the starting crystal-mother liquor mixture. The stirring crystal washing operation is the A type operation, and the stereotactic crystal washing operation is the B type transportation operation. The purification zone includes a set of stereoscopic washing divisions and a set of stirring washing divisions. Each of them has a front end and a rear end. Both ends refer to the upstream end and the downstream end with respect to the direction of normal movement of the solid phase. Two sets of divisions are installed alternately from the front end to the rear end along the vertical direction of the purification area. Therefore, the stirrer segment is interposed between the two sets of orientation segments. The purification zone therefore contains a large number of treatment stages. When a certain processing stage is the n-th stage, the stirring and washing subdivision is referred to as An subdivision, and the stereotaxic washing subdivision is referred to as Bn subdivision. The two subdivisions form a common subdivision set. Usually, the crystal after purification is melted and a part of it is used as the first washing liquid.

In each stirring section, the crystals and the liquid are lightly and repeatedly stirred to disperse the crystal nodules to release the impurities from the retained liquid to the free liquid. Agitation is achieved by means of active blades that are connected to the shaft. The M / S ratio is the ratio of the liquid amount to the crystal amount. M / S of Two-Phase Mixture in Stirred and Washed Section
The ratio is low, i.e. less than 2: 1 or when so 1.
Use a value lower than 5: 1. Since the two-phase mixture in the stirring section is a dense mixture with a low M / S ratio and is lightly stirred laterally, it is possible to suppress longitudinal stirring over a wide range. Moreover, the amount of mother liquor in the solid phase taken out from the A-type fraction can be kept low.

In the stereotaxic group, the crystal groups are compacted to form a crystal bed having a higher density than that of a naturally formed crystal bed. Properly increasing the compactness of the crystals in the stereotaxic compartments effectively reduces the impurities from the free liquid by backwashing and the amount of the mother liquor in the solid phase transferred from the compartments. Very important to do. Since the solid phase and the free liquid are transported in almost relative directions, the concentration of contaminants in the free liquid and the retained liquid changes sequentially depending on the position of the crystal bed. That is, the concentration of contaminants gradually decreases from the front end to the rear end. Therefore, transporting the impure liquid in this direction reduces the effect of the crystal washing operation. Since the solid phase is transported in this direction,
It is important to reduce the amount of liquid transported with the crystals or to backwash the solid phase transported in the segment during transport.
The present invention relates to methods of achieving these effects and the instruments used therein. There is a certain amount of liquid contaminants retained in the solid phase transported to the segment due to proper orientation of alternating orientation and stirring and washing operation and proper transport of solid phase and free liquid in the segment. It does not approach the limit value, but rather decreases gradually with a tone close to a geometric series. Then, crystals of very high purity are obtained at the rear end of the purification zone. In addition, the temperature in the purification zone also changes sequentially and rises from the front end to the rear end.

It is interesting to compare the first method of practicing the invention just described with the current column crystallijer. As you know, the current tubular crystallizer has a fairly deep static cleaning layer,
When the residual liquid in the purification zone and the miscellaneous mass in the free liquid are shown in the figure as a function of the thickness of the crystal bed, the curve is approximately displayed at some near value. Therefore, there is a limit to the purity of crystals that can be obtained in an ordinary crystal tower. It should be noted that increasing the thickness of the crystal bed in the crystal tower has no significant effect. The crystal bed simply descends into the column without stirring. Therefore, the contaminants in the retained liquid are not immediately released into the free liquid. A short circuit of the fluid is created in the crystal bed, and the short circuit tends to be retained as it is. On the other hand, in the method of the present invention, the crystal beds are alternately stirred and then re-formed to enhance the release of foreign matters from the retention liquid and effectively achieve the backwash of each stage. Moreover, although the height of each stereotactic cleaning section is small, effective cleaning is performed.

In the second method for carrying out the present invention, some purification operations and depletion operations of crystals are appropriately and alternately carried out, and the purification operation is carried out by transporting the solid phase and the free liquid in a nearly backflowing manner. I can go. The crystal stirring and washing operation is the A type transportation operation, and the crystal depletion operation is the B type transportation operation. This system includes a primary purification zone, which contains multiple treatment stages for primary crystal depletion zone, and a crystal melting zone. For example, in the n-th processing stage, there are an agitation and washing subdivision called an An subdivision and a dry depletion subdivision called a Bn subdivision, and the two subdivisions are one subdivision of a joint group. Therefore, the purification zone includes a set of crystal washing subdivisions and a set of crystal depletion subdivisions, the two subdivisions being arranged sequentially and alternately along a straight line or curve. The solid phase and the free liquid are transported in opposite directions and alternately through both sets of compartments.

The n-th processing stage consists of an agitated crystal washing section called an An section and a crystal depletion section called a Bn section. The two subdivisions within one processing stage are shared subdivisions. ShimeTsuta solid phase (K _A) n, which came out of the washing fraction District say that An amount Ward is separated into its Kyoyaku minute District depleted by the mother liquor (Bn minute-ku) (I _B) n and depletion solid phase (K _B) n It The depleted solid phase is transported in the direction toward the rear end to the next subsequent washing section, the A- (n + 1) section. Depleted solid phase (K _B)
n contains a certain amount of crystals (S _B ) n and a certain amount of retention liquid (M _B ) n.
The mother liquor (I _B) n first part (J _B) n and a second part (L _B) is divided into n, the respective stages in Kairyu liquid interstage transport liquid. The former is circulated to the original washing subdivision, and the latter is transported toward the front end to the preceding washing subdivision, A- (n-1) subdivision. The ratio of the inter-stage transporting fluid amount to the retentate of depletion solid phase, i.e. _{(M B) n (L B} ) n The ratio of relative amounts of is the important factor in determining the effect of the crystal cleanup . The cleaning effect is proportional to this, (L _B ) n / (M
_B ) n, the better it gets. This ratio is the cleaning ratio R _n
Also expressed. Washing ratio (L _B) or to increase the n, (M _B) to reduce the n or, or it can be by connexion increase to be used in combination with each other. High (L _B) increases the consumption of heat and requires that you circumfluence a melt of large quantities crystals to obtain the n value. Therefore,
It is desirable to obtain the desired wash ratio by reducing (M _B ) n. However, in practice, there is a limit to the degree of dryness that can be obtained. Achieving a high degree of depletion requires operation with expensive centrifuges. At low dryness, the wash ratio will be small,
The degree of crystal purification is low.

Due to the crystal depletion operation, most of the free liquid is excreted from the crystal free space and the gas phase occupies most of the free space. Therefore, most of the impurities are excluded from the intercrystalline free space. A small amount of retained liquid remains in the depleted solid phase. When the washing liquid is added to the depleted solid phase, the washing liquid becomes a free liquid, and the foreign matters in the retention liquid are transported to the free liquid. This operation can be accomplished by a simple dipping operation, or dipping and light agitation. Therefore, when the depletion operation is used for the type B transportation operation, only the immersion operation or the immersion operation with slight agitation is used for the type A transportation operation. Therefore, the stirring crystal washing operation in the second system operation can be replaced by the dipping operation.

The second type of operation involves washing and depleting alternately in multiple stages. It should be noted, however, that these procedures generally result in a high degree of purification with only a modest, mild washing and some depletion. Such a multi-stage method is superior to the existing purification method using a tubular crystallizer, which requires purification only by washing the oriented crystal. In addition, such a multi-stage method is superior to the centrifugal purification method in which the purification work is achieved mainly by excretion of the mother liquor. In other words, an excellent method can be obtained by appropriately repeating the crystal washing and the crystal depletion work. The same applies to the modified second method of operation described in the previous section.

The method of the present invention can be applied to both a continuous system and a batch system. The batch-type purification method achieves the purification effect by backwashing batchwise in one or more crystal washers. Mixture material of a certain quantity is introduced into one container it the first bed (K _{B) o.} It is a dipping bed or a depletion bed. The crystal bed is then washed in alternating A and B operations. In the batch operation, the nth-order A-type operation and the B-type operation are referred to as An operation and Bn operation, respectively. So type A operation is sequentially A-1, A-2, -----, An, ‐‐‐, AM
Operation; B type operation is B-1, B-2, -----, Bn, -----
---, BN operation is displayed. Crystal bed after An operation (K _A )
It is indicated as n, and the crystal bed after Bn operation is indicated as (K _B ) n. Using the terminology used in the continuous method as is, these crystal beds can be “inter-sub-zone transf
er solid phase ”or simply“ solid phas
e) ”. In a series with a large number of crystal washer, the front and rear ends of the purification zone indicate the position where the raw material mixture is introduced and the position where the first washing liquid is introduced. In such a series, the crystal washers are sequentially A-1, B-1, A-2, B-2, ----
-, An, Bn, -----, AN and BN subdivisions, and the crystal beds in a crystal washing machine are (K _A ) ₁ , (K _B ) ₁ , (K _A ) ₂ , (K _B ) ₂ ,-
---, (K _A ) n, (K _B ) n, ----------, (K _A ) _N and (K _B ) _N. In accordance with the nomenclature used for the continuous process, the crystal bed present in the crystal wash after these operations and implementations is also referred to as "solid phase transported to the section".

The third method of practicing the present invention is a method of backwashing the crystals in batches using a large number of crystal washers. Put a certain amount of crystal-mother liquor mixture as raw material mixture into one crystal washing machine,
And excrete liquid create a first depletion floor (K _{B) 0} and a mother liquor (L _{B) 0.} Mother liquor
(L _{B) 0} is excreted as the residual liquid from the series. First dry bed
(K _B ) ₀ is then the cleaning solution (L _B ) ₁ , (L _B ) ₂ , ----
-, Washed with (L _B ) _N and (L _B ) _{N + 1} , followed by mother liquor (L _B )
₁ , (L _B ) ₂ , ‐‐‐‐‐, (L _B ) _N-1 and (L _B ) _N are released, and the dry bed (K _B ) ₁ , (K _B ) ₂ , ‐‐‐‐ -, (K _B ) _N-1 and (K _B ) _N, and so on. The depleted solid phase is the clarified solid phase after performing n immersions and depletion operations. This purified solid phase is melted and becomes a melt. Part of the melt is the purified product, and the rest is the first wash liquid (L _B ) _{N + 1} . Hatsuhahaeki (L _{B) 1} is discharged to the system outside of the residual liquid. Therefore Noteworthy it is depleted crystals bed, crystal bed _{(K B) 0, (K} B) 1, -----, (K B)
_{The intercrystalline} space between _N-1 and (K _B ) _N is mostly occupied by the vapor phase. Therefore, the ratio of the amount of mother liquor to the amount of solid phase in each of these depleted beds is small. The operation of the third method can be replaced by another type A operation. For example, local stirring and washing work is performed at the place where the dipping work is performed. Or it can be replaced by another B-type operation. For example, backwashing work is done at the place where the dry work is done.
The operating procedure is almost the same as described above, but with a solid bed
_{(K B) 1, (K} B) 2, -----, (K B) N only it is immersed floor is different.

The fourth method for carrying out the present invention completes purification and purification in a purification zone in which a set of stirred crystal washing fractions and a set of solid phase transport fractions are alternately and sequentially installed from the first position to the second position. . The stirring crystal washing operation is the A type operation, and the solid transport operation is the B type operation. On top of that, there are the following features: (a) The solid phase is sequentially transported through both sets of compartments from both the first position to the second position in common.

(b) Some free liquids pass through both sets of compartments and are transported almost in the opposite direction to the transport direction of the solid phase through each pair of compartments.

(c) The remaining free liquid passes through the purification zone, bypasses the solid phase transport zone, and is transported almost in the direction opposite to the main transport direction of the solid phase.

The operation of this system has the advantages that the cleaning effect is enhanced and the pressure drop in the system is small, and it is possible to treat a mixture containing relatively fine crystals.

The fifth method for carrying out the present invention completes purification and purification in a purification zone in which a set of non-stirred washing zones and a set of solid phase transport zones are alternately installed. The solid phase passes through both the washing partition without stirring and the solid phase transport partition. Most free liquids bypass the solid phase transport compartment and only pass through the unwashed wash compartment. In this type of operation, the A-type operation and the B-type operation are simultaneously carried out in the solid phase transport section, and the B-type operation is carried out in the washing section without stirring.

In one type of operation, the effects of type A and type B transport operations are realized simultaneously. Examples of use include a backwashing and washing tower that is agitated by supersonic vibration in the horizontal direction, a backwashing and washing tower that is equipped with rotating vertical filaments or flakes, and a backwashing tower that has a static mixer (static mixer). There is. These stirring methods will be described below.

(a) Backwasher that stirs with ultrasonic vibration When the crystal-liquid layer is stirred with ultrasonic vibration, the transport rate of contaminants from the retained liquid to the free liquid increases, and the crystal bed is washed without the fluid short-circuiting. Yes, the first and second basic conditions can be satisfied simultaneously within the same processing pressure.

(b) Backwasher that stirs with thin slices or fine threads When a crystal bed layer is pushed through with a blade having an appropriate cross section, solids and liquids in front of the blades are pushed out, and solids and liquids are transferred to the rear surface of the blades. Moving. When solids and liquids migrate to the backside of the blade, the liquids migrate relatively quickly and form short circuit paths. The size of the formed short circuit increases as the blade cross section and the number of turns increase. Therefore, if a blade with a small cross section in the direction perpendicular to the direction of motion is used and stirring is carried out at an appropriate rotation speed, it is possible to satisfy the first and second conditions at the same time without creating too much liquid channeling path (Channeling Path). I can.

(c) Couhter Washer with a static Mixer A static mixer or static mixer in pipe (in
-Line motionless mixer is Kenics Corp.
oration) and Koch Engineering (Koch Engineer
ing Corporation) is manufactured and sold. The Kenics mixer fixes a series of spiral leaflets on the inner surface of the outer tube in a specific position. With its special tubular design, the fluid is split and flows in a unique shape, while being radially mixed.

(i) Flow Division In a static mixer, the fluid to be treated is a laminar flow and is divided into two streams at the front end of one leaf piece and flows according to the shape of the leaf piece. Then, the leaf pieces in the rear part are further divided into exponentially functioning multilayers.
The number of layers formed is 2 ^n, where ⁿ is the number of leaf pieces. By this operation, the diffusion rate of foreign substances from the retained liquid to the free liquid is increased.

(ii) Radial Mixing In both laminar flow and turbulent flow, the fluids treated in the static mixer are surrounded by their respective hydraulic centers. Circulates,
Therefore the fluids are mixed radially.
To be done. All the products to be processed are continuously and completely mixed with one another. As a result, the radial temperature, velocity, and constituent factors of the composition to be treated are almost eliminated. The static mixer enhances the transport of contaminants from the stagnant liquid compartment to the free liquid compartment by creating multiple layers by fluid splitting by multiple leaf pieces and radial mixing by tumbling circulation. The static mixer can suppress the formation of short circuit. Therefore, the first condition and the second condition can be satisfied at the same time by backwashing in the static mixer. Transporting a solid bed through static mixing results in considerable frictional loss and thus requires large thrust forces. Therefore, it is necessary to consider the equilibrium between the degree of frictional force loss and the degree of promotion of foreign matter transportation. Crystals can be purified using a static mixer with many leaf pieces.

There are two types of solidification methods. The first type is a solvent crystallization method (or crystallization from a melt), and the second type is a solute crystallization method. As an example of the former, the raw material mixture containing 90% para-xylene and 10% meta-xylene is partially solidified (frac
tional solidification) method. In this example para-xylene is also a solvent and it is the para-xylene that crystallizes. The main component of the crystal is called the first component. In this example, almost pure para-xylene (first component) is used as the initial washing liquid in the purification of the solid-liquid raw material mixture. An example of the latter is crystallization of the first solute. For example, when crystallization is performed from an aqueous solution containing potassium chloride (first solute) and sodium chloride (second solute), the main component of the crystal is potassium chloride, which is the first component. In this case, for the purification of the raw material mixture, water or an aqueous solution of potassium chloride is used as the initial washing liquid. The first wash used is not a melt of the first component.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows a crystal bed that has not yet been consolidated. It has agglomerates of erys
tals) can be seen divided by the free liquid between the nodules. Within each nodule there is a crystal retention liquid and an intra agglomerata free liquid. FIG. 2 shows the structure of the densified crystal bed.

FIG. 3A shows the retained liquid (reta described as the first basic condition).
The situation of transporting miscellaneous materials from an ined liquid to a free liquid is shown. FIG. 3B shows the intercrystalline free space explained as the second basic condition.
It shows the situation to reduce the amount of miscellaneous substances. FIGS. 4A to 4C show crystal washing and backwashing operations by stirring. 5A to 5C show a crystal soaking operation.
n) and mother liquor draining operatio
n) is shown.

FIG. 6 shows a first mode of purification zone for carrying out the present invention. The purification area consists of a set of stationary washing sub-zones (there are 5 areas in the figure) and a set of agitated Washi areas.
ng sub-zones) (there are also 5 subdivisions in the figure) are alternately discharged, and the agitation subdivision is connected to the stereotactic subdivisions of both upper and lower groups. Therefore, rotating blades are agitation elements, and
haft). Fig. 7 shows an ordinary tubular crystallizer (co
(nventional column crystallizer) and the crystal cleaning tower shown in FIG. The 1st main line and the 2nd main line show the function relationship between the concentration distributions of the impurities contained in the retained liquid and the free liquid in the ordinary tubular crystallizer, respectively, between the depths of the purification stage. The contaminant concentration in the liquid is seen to approach some limit. Therefore, the purity of the harvested crystals only approaches its limit. The third main line and the fourth main line respectively show the same concentration distribution in the purification column shown in Fig. 6 as a function of the number of plots. It can be seen that it is decreasing due to the relationship close to. Therefore, high-purity crystals can be harvested in this purification tower.

FIG. 8 shows a crystal purification system combining one main processing zone and one crystal melting zone. The main processing area includes a large number of processing stages. In the figure, five processing stages from 1 to 5 are shown. If there is one processing stage in the main processing area, for example, the nth stage, it has one An
It includes a cleaning partition called a partition and a crystalline depletion partition called one Bn partition. These two subdivisions are combined into one group (co
njugated set of sub-zone). The depleted raw material mixture (K _B ) ₀ is introduced into the main treatment area. The solid phase continuously passes through the main treatment stages and is transported through the washing and depletion zones of each stage. Each of these solid phase products
(K _A ) ₁ , (K _B ) ₁ , (K _A ) ₂ , (K _B ) ₂ , (K _A ) ₃ , (K _B ) ₃ , (K _A ) ₄ ,
(K _B ) ₄ , (K _A ) ₅ and (K _B ) ₅ . The purified, depleted solid phase (K _B ) ₅ emerges from the final stage, it is melted in a crystal melter and becomes a crystal melt. Some of AkiraTorueki a purification product D, back to the main processing ku the remainder as washing liquid (L _{B) 6.} A simple pass-through device is displayed in the crystal depletion zone. In this purification system, agitation and washing is type A transportation operation, and depletion work is type B transportation operation. The solid phase leaving the Bn subdivision is a drained cake. FIG. 9 is the eighth
The operation results of the purification system in the figure are displayed. Contaminant concentration (Z _B ) _N leaving the final stage and contaminant concentration of the three retained liquids in the raw material mixture
The relation between the washing ratio and the number of steps is also displayed, showing how (Z _B ) ₀ is related. This figure also shows that a high degree of purification is achieved by using a relatively small washing ratio and an operation having a number of stages suitable for practical use.

In the treatment zone shown in FIG. 10, a large number of shafts are turned around and the movement of a number of small stirring blades connected thereto feeds the two-phase mixture in the zone with a transverse stirring operation. This figure is a greatly reduced type of the stirring and non-stirring sections shown in FIG. It is also a system in which the stirring crystal washing and back washing are carried out simultaneously. FIG. 11 shows a treatment area in which stirring and washing and backwashing are simultaneously performed in each division. It may be a single continuous purification zone or multiple purification zones. It is also shown that the solid and free liquid are transported in relative directions, the two phases are agitated transversely, causing localized mixing of the two phases. The liquid-to-crystal ratio in the transverse agitation zone should be kept low, but may be less than 2: 1 or even reduced to less than 1.5: 1 but packed bed
Is higher than its proportional value. This will increase the consistency of the two-phase mixture. In the purification area shown in Fig. 12, the transverse stirring of the two-phase mixture in the area is achieved by ultrasonic vibrations. In the purification area shown in Fig. 13, it is shown that two-phase local agitation and backwashing work are performed simultaneously. Local agitation rotates a large number of fine threads or spins the flakes, suppressing the formation of fluid channeling paths.

FIG. 14 shows a crystal purification unit having a raw material feeding zone, a crystal purification zone and a crystal melting zone. The purification zone includes a set of static washing divisions (5 in the figure) and a set of stirring washing divisions (4 in the figure), which are alternately arranged. Then, one agitated subdivision is connected to the upper and lower two static subdivisions. FIG. 14a shows a cross section in the static segment. There is a control plate installed in the partition to help maintain a compacted bed and prevent it from being agitated by an agitator in an adjacent agitated partition. Figure 14b
Indicates an agitator that promotes local agitation of solid and liquid in the agitation section. FIG. 14c shows a rotator with inclined blades that densifies the crystal bed in the static section. FIG. 14d shows a rotating perforated plate with a sword. It supports the bed in the static compartment and also transports the solid phase from the compartment.

Figure 15 shows a crystal purification uni
t) is shown. This system is separated from the static section and the adjoining stirring section by a rotating perforated plate with a sword. The crystal bed in the static section is supported by a rotating porous plate and densified by a rotating blade. The solid phase transportation in the minute section is achieved by cutting the sword attached to the turning plate. Figure 16 shows a very simple crystal purification system. It does not have a perforated plate that separates the compartments, there are no rotating blades that make the floor of the static compartments dense, and there is no sword that can be used to transport the solid phase in the upper compartments. There is only one method, compacting means from the top of the tower.
Only. In this system, crystals in all fractions including agitated fractions are continuously bridged by crystals (continuous bridg).
ed structure), whereby the force is transmitted to the lower part. Therefore, the downward force applied to densify the crystal bed at the top of the purification zone and the total weight of the solid bed above a certain horizontal plane are transmitted to the horizontal plane through the bridge, and the crystal bed is densified.

Figure 17 shows the depletion bed washing tower. It consists of a set of stirred fractions labeled A-1 to A-5 and a set of non-stirred fractions labeled B-1 to B-5. The two sets of sections are alternately arranged facing upward. The crystal-mother liquor feed mixture is introduced at the bottom. The solid phase is pushed up by the blade in the stirring section. The washing liquid is added from the top and passes downward through the bed layer for excretion. FIG. 17a shows a cross section of the stirring section. FIG. 17b shows a cross section of the non-stirred section. FIG. 17c shows a developed view of the tower. The two-phase mixture in the compartment is agitated by the rotary leaf pieces in the agitated compartment, and the depletion bed is pushed upward. For large dry bed crystal washers, it is advisable to provide several washing rings in the stirred washing section. The tower shown may also be used as a submerged bed washer. In this case, the crystal-mother liquor raw material mixture may be fed from either the top or the bottom of the column.

Figure 18 shows the centrifugal crystal pu
rification unit). It has a first rotating body and a second rotating body. The first rotary body includes a rotary cylinder and a rotary net (or rotary bowl) attached to the rotary cylinder. The second rotating body includes a rotating shaft, a rotating arm and a blade. The purification zone is the first dry zone (Bo
The main treatment area is a large number of treatment stages 1,2 ----, N-1, N
(N in the figure is 4). The nth stage is composed of one An crystal washing section and a Bn crystal depletion section. The rotating net or rotating bowl there discharges the mother liquor from the crystals in each depleted zone. Within each crystal washing section there is a rotating arm with blades that stirs the crystal and still transports it to its co-depletion zone. The first rotating body rotates at a first rpm. The rotation speed is the speed at which the mother liquor is appropriately excreted from the crystal group in the depletion zone. The second rotating body rotates at the second rolling speed (second rpm). It may be slightly higher than or slightly lower than the first speed. In the washing section, the rotating arm agitates the mixture of crystal liquids and transports the crystals to their co-existing depletion section. The solid phase is transported from left to right and the interstage transport liquid is transported from right to left.

Figure 19 shows a plate-type crystal washer.
g column). It is apparently a plate-type distillation tower (plate-
Similar to type distillation column). Among them are a first set of plates, a second set of plates and a set of transport stages. Each transport stage includes a solid phase transport tube and a liquid transport tube. The solid-phase transport is radially outwardly transported on the first set of plates, but is radially radially inwardly transported on the second set of plates, and passes downward in the solid-phase transport pipe. Free liquid transport is carried radially inward on the first set of plates, radially outward on the second set of plates, and upward in the liquid transport tube.

5. Embodiments of the Present Invention 5-I Introduction FIG. 1 shows an unconsolidated bed of cr
ystals), and Fig. 2 shows the densified crystal bed (consol).
idated bed of crystals). The undensified bed has crystal groups (agglomerates of crystals) 1 and is separated by an inter agglomerate free liquid 2. Within the crystallite there are crystals 3 and a certain amount of liquid.
The part of the liquid that can be easily excreted from the crystal group or that can pass through it is the intra-agglomerate
ree liquid) 4. The remaining liquid retained by the crystals is referred to as retained liquid 5. Backwashing an uncompacted bed is inefficient because the displacing solution
liquid) selectively passes through the path occupied by the free liquid between crystal groups. This phenomenon is short-circuited (chan
nelling). If the undensified bed is compressed, a densified crystal bed as shown in FIG. 2 can be obtained. When a crystal group is attracted by a certain compaction method, a short circuit (channeling pa
The number and size of sses) are greatly reduced. The dense bed contains crystals 3, free liquid 4, and retained liquid 5.

In order to effectively carry out the crystal washing work, there is an appropriate pressing frequency range. Compressing more than a certain amount is necessary to suppress short-circuiting, and is suitable for the crystal bed.
y) means that there is a practical rate of displacemen.
needed to get t).

FIG. 3A shows an operation of transporting impurities from the retained liquid to the free liquid, which is the first basic condition. In the figure, all the crystals in the crystal group are collected and shown by the disc area 5, and the retained liquid is shown by the ring 6. The free liquid between the crystal groups and inside the crystal groups is indicated by the area 7 outside the retention liquid. The operation of the first condition is to remove impurities from the retained liquid section 6 to the free liquid section 7
Is to transport to. FIG. 3B shows an operation of reducing the amount of impurities from the free space between crystals, which is the second basic condition.
In the figure, the crystal is zone 5, the retained liquid is zone 6, and the free liquid is zone 7.
Indicate.

FIGS. 4A, 4B and 4C show the effect of sequentially and locally agitating a certain crystal bed (type A operation) and further backwashing (type B operation). In the method of the present invention, this two-step operation is repeated. FIG. 4A shows the state of the bed before performing the type A operation, and FIG. 4B shows the state of the crystal bed after performing the type A operation. It is also the floor condition prior to performing Type B operations. FIG. 4c shows the state of the crystal bed after carrying out the type B operation. Fourth indicates that the reduced small in Figure A and the at the impurity concentration in the retentate by A type operation from (C _{R) 1} Figure 4 B to (C _{R) 2,} the impurity concentration in the free liquid in the same time It shows that it increased from (C _B ) ₁ to (C _B ) ₂ . 4 B and C, the concentration of impurities in the free liquid by the B-type operation depends on the B-type operation.
It shows that (C _B ) ₂ is reduced to (C _B ) ₃ and the concentration of impurities in the retained liquid changes slightly and changes from (C _R ) ₂ to (C _R ) ₃ .

FIG. 5 A, B and C show the effect of sequentially applying the A-type operation by the soaking operation and the B-type operation by the draining operation to the drained crystal bed. I'm here. These two operations are repeated for one crystal bed. 5A and 5B show the state of the crystal bed before and after the dipping operation, and FIGS. 5B and C show the state of the crystal bed before and after the excretion operation, respectively. Fig. 5A shows the intercrystalline free sp
ace) 7 indicates that it is filled in the gas phase. FIG. 5B shows that the intercrystalline free space is occupied by the liquid phase after the immersion operation. By this operation, the impurity concentration in the retained liquid is (C
It shows that _R ) ₁ is reduced to (C _R ) ₂ . FIG. 5C shows that the free space between crystals after the excretion work is again occupied by the vapor phase. Since the amount of free liquid in the free space is reduced, the amount of impurities in the free space is also reduced.

In order to explain the state in which the crystal bed is formed in the static section in the purification tower of the present invention, it is important to study the mechanism by which the crystal bed is formed from the suspended state. For convenience, the following terminology is defined: “naturally formed bed”.
d), "bed with enhanced compactio"
n) and “bed without enhanced compac”
tion).

When the suspension is batch-wise settled in a tank, the settling distance of particles of different sizes is different within a certain time. One particle continues to settle until it is supported by the crosslinking of the other particles. Coarse particles stop settling before small particles. The small particles may stay on top of the large particles for a while, but they also enter the gaps between the large particles. Consolidation trickling (consolidation tricklin
g), which is a characteristic of the precipitation process of small particles. Instead, large particles are supported by cross-linking and cannot settle further.
The precipitation of small particles during the consolidation process is more mellow than that in suspension, but the degree of compaction of the resulting crystal bed.
compaction) is mostly higher. Eventually, the total number of particles settle down regardless of size. Then, self-supporting cross-linking of particles is possible. The tightness of the formed crystal bed is measured by the porosity of the crystal bed. The lower the porosity of the bed, the higher the tightness. Applying static pressure to the naturally formed crystal bed has practically no effect on compaction. This is because the applied force is transmitted to each part on the surface of the particle and they are erased by each other. Therefore, the force transmitted to the self-supporting structure collapses the structure, and if the crystal bed is provided, it becomes a strong structure. Therefore, the tightness increases. A bed in which a precipitate is formed from a suspension without applying an external force other than gravity to particles is called a "naturally formed bed" or "bed without enhanced compaction".
In a naturally formed deep bed, the tightness at the bottom is higher than that at the top. This is because the weight of the floor is transmitted through the structure of the floor to make the bottom floor tight. Therefore, the average tightness of a naturally formed bed is a function of the depth of the bed.

In the purification tower of the present invention, a set of static washing divisions and a set of stirring washing divisions are alternately arranged. The tightness in each static segment is an important factor for the effect of washing the crystals and the carry-over amount of the liquid during the transportation of the solid phase in the segment. For the purpose of accurately grasping the characteristics of the crystal bed in the static washing section, the reference bed is used for convenience. Compare the tightness of the practical bed with that of the reference bed. The reference floor used in this book is a "naturally formed floor"
(Steady state naturally formed bed). This reference floor is specified in the next section.

The front end of the static washing section has a perforated plate and is connected to the previous stirring section, and the rear end is connected to the latter stirring section with another perforated plate.
The solid phase is introduced from the front end of the partition and goes out from the rear end.
The free liquid is introduced from the rear end of the division and comes out from the front end.
Then, the stable state is maintained in the division. The floor formed in this section is called "steady state natural formation floor" (steady state
Naturally formed bed) or "naturally formed bed". The bed formed in this section is a self-supporting structure of crystals, in which no other external force acts on this structure except the frictional force of the flowing liquid and the gravity applied to the bed.

There are two methods for increasing or strengthening the tightness of the bed formed in the static washing section to significantly exceed the natural tightness. As previously mentioned, the bed can be made tight by conducting forces to the self-supporting structure of solid particles within the bed. One way is to apply a mechanical force to the floor structure. The mechanical method is to use a piston, a screw conreyon, and a rotary machine equipped with an inclined blade to make the crystal bed tight. Another method is to convey the force to the structure of the bed by the total weight of the beds including static beds and agitated beds located higher than a certain section, and to make the floor of the section closer. In order to convey the importance of the higher section to the structure of the floor of this section, it is not necessary to use a perforated plate separating the section and the stirring section before it. A crystal bed that is denser than the naturally formed crystal bed is called a reinforced dense bed.

5-II Operation Results of First Method and Second Method for Implementing the Present Invention The operation results of the first method and the second method for implementing the present invention are described in this section.

5-IIa Results of operation by the first method Figure 6 shows a general system that can be operated by the first method. Figure 7 shows this method and the existing column crystallizer.
r) A comparison chart of operation results. There is a purification tower 8 in this system, and there are an upper end 9 and a lower end 10, and the first set of stirring and washing subdivisions 11a to 11e, which are called A-5 subdivisions, respectively.
1 from a set of static washing subdivisions 12a called B-5 subdivision from B-1
There is 2e. Separator plate that is perpendicular to the radial direction in each static section
13 divides the subdivision into several small rooms. In each stirring section, a stirring blade piece 14 is connected to the shaft 15 and rotates with it. It is also possible to twist the stirring blade to make the crystal bed tighter. Therefore, the blades have a function of stirring the floor in the stirring section, and have a function of making the floor tight in the static section. The static mixer described above can also be installed in this static mixing section to promote the transport of impurities.

The crystal-mother liquor raw material mixture 16 is introduced from the upper end of the column, and the first washing liquid 17 is introduced from the bottom. A certain amount of purified solid phase 18
Is discharged from the bottom, and the impure liquid 19 is taken out from the upper end.
The solid phase passes through the static and agitated compartments and descends one after another. The free liquid flows upward through the compartments. Solid phase was transferred to a stirred partial Zone A-1 to A-5, referred respectively from (K _{B) 0} and (K _{B) 4} fluid. The solid phases emerging from the stirring fractions A-1 to A-5 are referred to as (K _A ) _{1 to} (K _A ) ₅ fluids, respectively. Stirring division A-5 to A
Free liquid entering -1 is referred to, respectively from the (L _{B) 5} and (L _{B) 1} fluid. Free liquids that can be separated from the stirrer sections A-5 to A-1
It is called (L _A ) _{5 to} (L _A ) ₁ fluid. Solid phase 18, which is purified is melted, part of the melt and purify the product, the rest is a washing liquid (L _{A) 6.}

In order to carry out an effective crystal washing operation in a static zone, it is necessary to press the crystal bed in the zone so that the crystal bed has a tightness much higher than the natural tightness. There are two methods previously mentioned to increase the bed tightness of this line. Since the concentration of impurities gradually decreases in the downward direction, transporting the impure liquid in this direction reduces the operation effect of this purification tower. What is unavoidable, however, is that the liquid that stays in the solid phase transported in this section travels exactly in this unfavorable direction. The detrimental effect of this movement of stagnant liquid can be reduced using one or both of the following methods.

(i) Reduce the amount of retained liquid in the solid phase transported to the minute section.

(ii) Backwash the solid phase being transported in both sections.

Both methods are used in the purification tower above.

The phillips process is an example of the successful successful commercial application of the countercurrent column partial crystallization method. The tower used includes one crystal forning zone, one a deep non-aggitated crystal purification zone and one crystal melting zone. The crystal bed in the purification area is not agitated. Since the solid phase and the free liquid are transported in the relative direction, the concentration distribution of impurities can be formed in the purification zone. Curve I, 20-21-22 in FIG. 7 shows the relationship between the impurity concentration in the retained liquid and the depth of the column. Curves II and 23-24-25 show the relationship between the impurity concentration in the free liquid and the depth of the tower. In the figure, both curves are seen to approach some limit. The solid phase discharged from the bottom of the column is melted and becomes a purified product, and since the solid phase contains the retention liquid, the impurities contained in the retention liquid become the impurities of the purification product. Therefore, there is a practical limit to the purity that can be achieved with current tower crystallizers. Even if the length of the tower type crystallizer is added, the effect obtained by it becomes smaller. The main reason for this is that the crystal bed formed in the tower is not agitated, and the impurities staying in the crystal group are not rapidly released to the free liquid only by settling in the tower. Is to remain as a short circuit.

In the figure, curve III20-26-27-28 and curve IV23-29-30-31 show the distributions of the impurity concentrations in the retained liquid and the free liquid in the purification tower of the present invention, respectively. Eight stirring and washing subdivisions (A-1, A
-2, ---------- A-7 and A-8 subdivisions) and eight static subdivisions (B-1, B-2, -----), B-7 and B-8 subdivisions Including). (Z _B ) ₀ and (X _A ) ₉ represent the concentration of impurities in the stagnant liquid and the washing liquid in the raw material solid-liquid mixture, respectively. (Z _A ) i and
(Z _B ) i represents the concentration of impurities contained in the solid phase retention liquid transported at the lower ends of the Ai and Bi compartments, respectively. (X _A ) i
(X _B ) i represents the concentration of impurities in the free liquid transported at the upper ends of the Ai and Bi sections, respectively. As shown in the figure, the sequence formed by the concentration of the impurities contained in the liquid at the corresponding position in these sections is close to the geometric sequence. Then [(Z _B ) ₀ , (Z _B ) _1-
‐‐‐, (Z _B ) ₈ ], [(Z _A ) ₁ , (Z _A ) ₂ ‐‐‐, (Z _A ) ₈ ],
((X _B ) ₁ , (X _B ) ₂ ------, (Z _B ) ₈ ], ((X _A ) ₁ , (X _A ) _2-
---, (X _A ) ₈ , (X _A ) ₉ ], four sets of sequences are created. The concentration of impurities contained in the liquid in each set is sequentially reduced. Moreover, it should be noted that we do not approach a certain limit.
Therefore, with a suitable number of subdivisions, the concentration of impurities can be reduced to a very low degree, for example to one part per million or even lower.

As will be shown later, the depth of each subdivision is shallow. The depth of the static section is about a few inches and 1 or 2 feet, and the depth of the stirring section is even smaller. Therefore, the effective column that can produce one ultra-pure chemical is a relatively short column. Then, also in the stirring section, it is sufficient to promote local stirring with relatively mild stirring. In summary, the purification tower of the present invention can be operated when the crystal bed moves through the tower by alternately operating static washing and stirring washing, and by appropriately carrying out the transportation of the solid phase and the free liquid in the interval section. You can renew yourself and improve the effect of operating the tower.

5-IIb Operation results by the second system Fig. 8 shows a general system in which the second system process can be carried out, and Fig. 9 shows the operation results of this system.

The operation of the second method is based on the discovery described below. A high level of cleaning effect can be obtained with a relatively low level of cleaning and depletion at each stage by carrying out alternating multi-stage cleaning operations and transporting the solid phase and free liquid in roughly opposite directions. I understand that I will be. The degree of cleaning action and the degree of depletion action required for this are, respectively, depending only on the washing action (such as a tower crystallizer or centrifugal precipitation method) and only on the depletion action (such as gravity or centrifugal excess). A low level is sufficient. Therefore, the crystal purification method of the present invention is an overall improved and economical method as compared with the conventional crystal purification method. “Substantiall” in the text
y reduced degree of washing and “moderate washing” (mod
The erate degree of washing indicates the degree of washing sufficient to achieve the purpose of washing at each step of the method, and likewise “substantially reduced depletion degree”.
gree of draining) and “moderate dryness” (moderate deg
ree of draining) indicates the degree of depletion sufficient to achieve its cleaning purpose at each stage of the method.

The performance of sedimentation centrifuges and centrifugal filters is described in "Handbook of
4,5 of separation technique for Chemical Engineers "
There is an introduction in the section. These performances are reference performances.

FIG. 8 shows a crystal purification system of the second process. This system consists of one main treatment zone 31 and one crystal melting zone 32. The main treatment area includes a number of treatment stages. In the figure, step 1
There are 5 more steps. There is a washing section (denoted by An section) and a crystal depletion section (denoted by Bn section) in one treatment stage (referred to as nth stage) in the main treatment section. The two subdivisions form one shared subdivision. Therefore, steps 1 to 5, 33e rather than 33a
5 crystal washing subdivisions 34a to 34e, and 5 depletion subdivisions 35
There is 35e than a. These washing subdivisions are labeled A-1 through A-5, respectively, and these depletion subdivisions are labeled B-1 through B-5, respectively. The main treatment area is enclosed within the limits shown by the dotted line and has a top first end and a bottom second end. Crystal washing in each washing subdivision is stirring washing or back washing operation. Crystal depletion within each depletion zone is a simple gravity overwork or centrifugal overwork. In the depletion subdivision in the figure, only gravity is shown. Although not shown in the figure, the solid-liquid mixed raw material (K _A ) ₀ is depleted in the first-depleted zone B- ₀ to form excess (L _B ) ₀ .
It is discharged from the grid. The depleted solid phase (K _B ) ₀ is introduced into the main treatment zone from the first end. Part of the melt (L _B ) ₆ made in the crystal melter is introduced into the main treatment zone from the second end. The depleted solid phases released from the fractions B-1 to B-5 are represented by (K _B ) ₁ to (K _B ) ₅ , respectively, and are indicated from A-1 to A
The solid-liquid mixtures released from the compartments up to -5 are represented by (K _A ) 1 to (K _A ) 5, respectively. The liquid exiting from the minute-ku, from B-1 to B-5 is displayed in each (I _{B) 1} than (I _{B) 5.} (I _B) Some of the ₁ becomes stage in circumfluence (J _{B) 1,} to flow it A-1 minute ku twice. remaining
(L _B ) ₁ is discharged from the grid. Similarly, (I _B ) ₂ , (I _B ) ₃ ,
(I _{B) 4} and (I _{B) 5} portion of the flowing liquid are each Dan'nai circumfluence solution (J _{B) 2,}
(J _B ) ₃ , (J _B ) ₄ and (J _B ) ₅ , which are A-2, A-3 and A-4, respectively.
And divert to A-5. The residue is the interstage transport liquid (L _B ) ₂ , (L
_B ) ₃ , (L _B ) ₄ and (L _B ) ₅ are transported to A-1, A-2, A-3 and A-4 subdivisions, respectively. Depleted solid phase from the last stage (K _{B) 5} is melted by crystal fusion 32. Some of the melt becomes purification product D. The rest becomes the washing liquid (L _M ) ₆ and is introduced into the A-5 division. In general, the operations carried out in the nth treatment stage are as follows: (a) the depleted solid phase from the n-1th stage, the interstage transport liquid (L _B ) _{n + 1} from the n + 1th stage. The interstage circulating liquid (J _B ) n is brought to the An compartment and the resulting mixture is discharged as solid phase (K _A ) n.

(b) (K _A) is depleted in n solid phase Bn min Ward, a depletion solid phase (K _B) n and a mother liquor (I _B) n.

(c) Part of the mother liquor becomes the in-stage circulating liquid (J _B ) n, which is
Divert to a division. The remaining portion becomes the interstage transport liquid (L _B ) n and A
-Introduced in (n-) subdivision.

The liquid streams (L _B ) ₀ and (L _B ) ₁ obtained from the B-0 and B-1 fractions are residues. It contains almost all of the impurities in the raw mixture.

Retentate volume ratio of interstage transport fluid volume and depleted in solids phase, i.e. (L _B)
The ratio of the amount of n to the amount of (M _B ) n is one important factor in determining the operation efficiency of crystal cleaning: as the ratio of (L _B ) n / (M _B ) n increases. Efficiency also increases. This ratio value is represented by the wash ratio Rn. Washing ratio may be due connexion increases or the (L _B) or increasing n, or reducing (M _B) n, or both. High (L _B )
The n value requires a large amount of circulation of the crystal melt. Therefore, increased energy consumption is required. Therefore, the desired desired cleaning ratio is achieved by reducing (M _B ) n. That is, to increase the degree of depletion within the Bn subdivision. There is a suitable degree of dryness for practical use: extra centrifugal force work is required to obtain a high degree of dryness, and if a low degree of dryness is used, the washing ratio becomes small and the effect of crystal purification becomes poor.

The impurity concentration X _D in the product is related to the impurity concentration (Z _B ) _{N in the} final stage mother liquor. Impurity concentration leaving the final stage (Z _B ) _N
Is the impurity concentration (Z _B ) of the stagnant liquid in the solid-liquid raw material feed
_0, washed ratio R _1, R _2, ----, related to the number N of R _N及段. FIG. 9 shows the relationship between (Z _B ) _N and R _n and N. The values in the figure were obtained by assuming that (Z _B ) ₀ = 0.1 and that the washing ratios were all the same.

Curves 36a to 36i have (Z _B ) ₀ = 0.1 and R _n are 1, and 1, respectively.
When 5, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0 and 10.0, the relationship between Z _N and the respective number N of stages is shown. As shown, a high degree of purification can be obtained with an appropriately low wash ratio and an appropriate number of stages. For example, when (Z _B ) _N = 0.1 and R _n = 2.0, the number of steps required to reduce (Z _B ) _N to one part per million (1 ppm) is 18. Similar results show that N is 11th when R _n = 3.0 and N is 8th when R _n = 4. 2 to get R _n = 2.0 when (M _B ) _N / (K _B ) _N = 0.1
This is achieved by circulating 0% of the crystal melt as a wash (L _M ) _N. Similarly, R _n = 3.0 can be obtained by circulating 30% of the crystal melt. --- etc. In the system of the present invention, the equipment cost for one stage and the operating cost for one stage are considerably low, so that the total cost of operating the multistage system is low. So this system achieves a high degree of purification of crystals. To reduce the operating cost for each stage, it is necessary to maintain the degree of depletion in each depletion subdivision appropriately.

As already mentioned, in the third method for carrying out the present invention, the cleaning operation is achieved by backwashing operation in a botchwise manner with a large number of crystal washers. The first depleted bed (K _B ) ₀ is subjected to a series of immersion and liquid excretion operations. The results of the third method operation are similar to those of the second method operation.

5-III Another Method for Carrying Out the Invention In the treatment section 37 shown in FIG. 10, the transverse stirring of the two-phase mixture is driven by a plurality of shafts 39 and swirled by a plurality of small stirring vanes. Achieved by 38. Inhibits long range mixing of both phases in the transport direction. This is achieved by keeping the M / S ratio of the two-phase product in the zone low and performing local agitation with small blades.

FIG. 11 shows a general system in which the AB operation described above is performed.
In this system, the solid phase is transported from the first end 40 to the second end 41 and the free liquid is transported from the second end to the first end. Agitating in the transverse direction and backwashing are simultaneously performed in the AB-1 to AB-10 divisions. These subdivisions may form individual subdivisions or a continuous subdivision.

FIG. 12 is a kind of FIG. 11 and the required transverse stirring is achieved by ultrasonic vibration. Numerous transducers
40 is connected to the pipe wall 41. FIG. 13 is another system of FIG. 11, and the required localized agitation is achieved by rotating the thin wire 42 or the thin blade piece connected to the rotating arm 43.

In the crystal purification system shown in FIG. 14, the raw material supply zone 44a indicated as A-1 zone, the main crystal purification zone 45 similar to that shown in FIG. 6 and the crystal melting indicated as M-6 zone There is a ward.
The purification zone has a set of stirred zones 44a-44e labeled as A-1 to A-5 and a set of static zones 47a-47e labeled as B-1 to B-5. In each static division, the division is divided into small chambers in the radiation direction and by the vertical adjusting plate 48. There is a central shaft 49, which comprises a crystal feeder 50, a first set of solid phase transporters 51, a set of stirrers 52, a second set of solid phase transporters 53, a solid phase discharger 54 and There is a stirrer 55 which agitates another crystal to enter the melter. As shown, the feeder, agitator, and transporter are all attached to the central shaft and rotated accordingly. Heating coil 56 in the crystal melting zone
Is provided with a heat transfer medium inlet 57 and its outlet 58.

In order to make the crystal washing work effective in the static zone, it is necessary to press the crystal bed in the zone to a compaction density considerably higher than the natural compression degree. This is accomplished by operating the feeder 50 and solid phase transporter. Therefore, these solid transporters can also be used as a pressure means for the crystal bed.

FIG. 14a shows a cross section of a static segment. A vertical, radial wall 48 separates the compartments to form chambers 59a-59f. The crystal bed descends through these chambers. This wall helps maintain the tightness of the crystal bed and prevents the crystal bed from being agitated by the agitator in the adjacent section.

Figures 14b and c show a type of stirrer. It promotes local mixing of crystals-liquid groups in the agitated compartment and is used to break the crystallites. Thus, the impurities are released from the crystal group and transferred to the free liquid, which aids in the recrystallization of the crystal. Local stirring of the crystal groups and the free liquid is important in this operation. The illustrated stirrer 44 has a radiating arm 60 and a blade piece 61, and the blade is inclined with respect to the traveling direction. The rotation of the stirrer causes its movement to be approximately coplanar. The wings attached to the first and third arms are inclined in one direction, and the wings attached to the second and fourth arms are inclined in opposite directions. As they descend from the crystal bed and pass through the stirred compartment, these crystals alternate inwardly and outwardly and can be intimately mixed with the upwardly migrating free liquid. It should be noted that the movement of the crystal groups in the compartments is generally coplanar, although some components move downward along the falling bed.

FIG. 14c shows the structure of the solid phase transporters 51, 53 in FIG. The wing piece 62 is inclined downward. The first transporter 51 at the bottom of the static zone cuts the crystal group from the crystal bed of this zone and transports it to the next stirred zone. A second transporter 53 at the bottom of the stirred compartment takes in the crystal-liquid mixture from this compartment, presses it in, packs out most of the liquid, and transports the pressurized crystals to the next static compartment. The second transporter also impinges on the crystal bed in the next static segment.

FIG. 14d shows a turntable 63 with perforations 64 and a sword 65. Such a rotary perforated plate supports the bed in the static zone and at the same time takes out the solid phase from this zone. Therefore it is
14 Can be used in place of the first solid transportation means in the figure. In Figure 14,
The rotary perforated plate 54 transports the crystals from the final static zone to the melting zone as a solid transportation means.

Figure 15 shows a modified crystal purification unit. This unit is similar to that shown in FIG. 14 but modified as follows: A static perforated plate 66 with a sword knife 63 similar to that shown in FIG. Separate from the next stirring section. The crystal bed in the static section is supported by the rotary porous plate 66,
14 It is compressed with the rotary blades shown in Fig. C. The crystal-liquid mixture in the stirring section is stirred by the stirrer 68.

FIG. 16 shows another modified crystal purification unit. This unit is also similar to the one shown in Fig. 14 and has the following characteristics: (1) There is no rotating or non-rotating perforated plate separating the static section from its adjacent stirring section. (2) There are no rotor blades used for compressing the floor of the static section. (3) There is no rotary sword used for transporting the solid phase in the 3-minute section.

The stirrer 68 is used to stir the stirring section. In the example of FIG. 16, there is only one floor compactor 69 at the top of the tower. In this system, the crystals in all the sections including the stirring section continuously form a crosslinked structure, through which the force for compressing the bed is transmitted. Therefore, the downward force exerted by the compactor at the top of the clarification zone and the total weight of the solid bed above that horizontal plane is imparted to the bed at that horizontal plane, compressing the crystal bed there through the bridged structure. The crystal bed can be further packed by using a stirrer equipped with inclined blades.

Figure 17 shows one dry floor cleaning tower. For that, A rather than A-1
-There is a set of agitated subdivisions that are displayed as 5 subdivisions and a set of static subdivisions that are displayed as B-5 subdivisions from B-1. The divisions of both sets are alternately arranged upward. The raw material mixture of crystal-mother liquor is fed from the bottom, and the solid phase is pushed upward by the blades in the stirring section. The washing liquid is added from the upper end, passes downward through the crystal bed, and is finally excreted. FIG. 17a shows a cross section of the stirring section, and FIG. 17b shows a cross section of the non-stirring section. FIG. 17c shows a developed view of the tower. In the stirring section, the rotor blade 70 stirs the two-phase mixture in the section and pushes the depleted bed upward. In the static zone, the control plate 71 prevents the crystal bed rotation in this zone. The above-mentioned in-line motionless mixer or static mixer can be installed in the static section. It should be noted that this purification tower can also be used as an immersion floor cleaning device. However, in this case, the raw material mixture of the crystal-mother liquor may be introduced from the upper end, and the initial washing liquid may be introduced from the bottom.

FIG. 18 shows the centrifugal crystal purification system of the present invention. It is the first rotating body 72 rotated at the first rotation speed (rpm) ₁ and the second rotation speed.
There is a second rotating body 73 rotated at (rpm) ₂ . Besides, B-0
The first depletion zone and the main treatment zone, called subdivisions, are in the first rotating body. The first rotating body is divided into sections by the adjusting plates 75a and 75b. Washing division 76 with four treatment stages shown in the figure
The a, 76b, 76c, and 76d are represented by A-1 to A-4 subdivisions, respectively, and the depleted subdivisions 77a, 77b, 77c, and 77d are represented by B-1 to B-4 subdivisions, respectively. Centrifugal filter 79 is installed in the first depletion zone and all the depletion zones. These transformers are part of the first rotating body and are rotated together at the first rotating speed (rpm) ₁ . If the crystal particles are small, use a sedimentation centrifuge (sedime centrifuge) instead of centrifugation.
ntary centrifuges) may be used. Rotating arm 80, stirrer 8
1 and the crystal transporter 82 are included in the washing section. This is a part of the second rotating body and is rotated at the second rotation speed (rpm) ₂ . The first rotation speed is moderate, and the solid phase introduced into the depletion zone is also depleted only to an appropriate degree. The centrifugal force used in the centrifuge may be an appropriate degree. The second speed is slightly higher or slightly lower than the first speed. Therefore, the objects contained in the washing subdivision are stirred by a suitable stirrer 81 and the solid phase (K _A )
n is transported by the transporter 82 to the corresponding depletion zone.

In operation, the solid-liquid starting mixture (K _A ) ₀ is introduced into the B-0 zone and is depleted to (K _B ) ₀ and (L _B ) ₀ . (L _{B) 0} is discharged from the system in impure solution. The solid phase (K _B ) ₀ is introduced into the treatment zone, the depleted solid phase is taken from the final stage (K _B ) ₄ to the crystal melter 78 and melted therein. A part of the melted liquid becomes the purified product D, and the residual portion (L _B ) ₅ is transported to the A-4 division.
Operations performed at the n-th stage is substantially similar to that described in strains of FIG. 8 before, it will be described next briefly second stage as an _{example: (1) (K B)} 1 to (L _B ) ₃ and (J _B ) ₂ and A-2 are mixed. It is stirred with stirrer 81 to form a solid-liquid mixture (K _A ) ₂ .

(2) The solid-liquid mixture (K _A ) ₂ is scraped off from the section A-2 and transported by the transporter 82 to the section B-2.

(3) (K _{A) 2} is depleted in Yotsute B-2 minutes wards the centrifugal excessive vessel 79, a depletion solid phase (K _{B) 2} and the mother liquor (I _{B) 2.}

(4) (I _B) circumfluence solution of ₂ of a portion within the stage (J _{B) 2,} and the adjusting plate 7
It is returned to the A-2 division through the opening 81a on the 5b.

(5) The mother liquor of residual interstage transport liquid (L _{B) 2,} and the is transported to A-1 min-ku.

The operation of the other steps is similar. It should be noted that the rotation speed of the second rotor is higher or lower than that of the first rotor, and the rotation is continued by stirring the washing section and transporting (K _A ) n between stages. You can Also noteworthy is that when the first rotor is rotated at a suitable rpm, the solid-liquid mixture (K _A ) n is also depleted to a solid phase (K _B ) n.
The rpm of the first rotor is chosen in a simple optimization study based on the calculations used to make FIG. Higher rpm results in a higher degree of excretion of liquid (ie a lower (M _B ) n / (S _B ) n ratio) and a higher wash ratio. However, high rpm also requires high equipment costs and high operating costs.

Since it is a multi-step operation, a fairly high degree of purification of crystals can be achieved even with an appropriate degree of excretion of liquid. The centrifugal force used is also much lower than a normal centrifuge that achieves the same degree of purification.
The depleted solid phase from the final stage (K _B ) ₄ is collected in the fixed chamber 83 and sent to the crystal melter 78. Part of the melt becomes a purified product, and the remaining portion (L _B ) ₄ is transported by pump 84 to the A-4 section. (L _B ) ₀ and (L _B ) ₁ are collected in the stationary ring 85 and discharged therefrom.

Figure 19 shows the plate tower crystal washing system. There A-1 or A
-A set of stirring crystal washing subdivisions 86, B-1 to B-, which are called subdivisions
There is a set of transport sections 87 called Section 4 and a crystal melter 88 called Section M-6. The A-2 subdivision has two constituent subdivisions called A-2a and A-2b. Similarly, A-3 and A-4 subdivisions are A-3a and A-3b, respectively.
There are two constituent divisions, called divisions A-4a and A-4b. B-1, a-2, B-2a,
Solid transport section 89 called B-3a and B-4a and B-1b, B-2b, B-3b
There is a liquid transport section 90 called B-4b. The remaining portion 91 of the transport section, called B-1c or B-4c, is left empty and not used. The solid phase is sequentially A-1b, B-1a, A-2a, A-2b, B-2a, A-3a, A-
Transported through the 3b, B-3a, A-4a, A-4b, B-4a and A-5a sections and placed in the melter M-6. Free liquid bypasses the B-4a or B-1a subdivision and sequentially A-5a, B-4b, A-4b, A-4a, B-3b, A-3b, A-
Transported through 3a, B-2b, A-2b, A-2a, B-1b and A-1b subdivisions. The solid phase moves inward on the plates in A-1b, A-2b, A-3b and A-4b, and moves outward on the plates in A-2a, A-3a and A-4a compartments. To be done. A small amount of free liquid flow (L _A ) _2a , (L _A ) _3a , (L _A ) _4a and (L
_A ) _5a was separated from the two-phase mixture by a filter installed in the A-2a, A-3a, A-4a and A-5a sections, and B-1a, B-2a and B-3a respectively.
Bypassing subdivisions A and B-4a, they are introduced into subdivisions A-1b, A-2b, A-3b and A-4b. Both phases mixture entering the B-1a min Zone was tense Therefore some liquid (L _{B) 1a} leaves a minute ward, it enters the A-1a min Ward through the B-1b content Ward. Similar operations can be performed in the B-2a and B-3a subdivisions. The pressure drop in this system is small because most of the liquid phase bypasses the compression beds in the B-1, B-2, B-3 and B-4 compartments. For the same reason, this system is able to purify solid-mother liquor mixtures containing small particle crystals.

6. Industrial Applicability The method of the present invention is an energy-saving method and can highly purify crystal components in chemical products (Super purification). Therefore, this method can produce high-purity simple substance to contribute to Polymer industries, and also produce high-purity chemicals to produce electronic industry, pharmaceutical industry,
It can make a great contribution to the agrochemical industry and other industries. This method is also used for separation and purification of azeotropic mixtures.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventors Chieng, Chien-En USA, New Mexico 87111, Albuquerque, Northeast, La Playa Treat 9605 (56) References JP-A-58-199002 (JP, A) US Patent 3691832 (US, A)

Claims (40)

[Claims] 1. A purification method for washing an impure crystal containing a mother liquor with a washing liquid in one purification zone to obtain a purified crystal of a first component and a residue containing one or more solutes. The purification zone used consists of two sets of divisions, type A and type B, and the divisions that make up the first set are A-1, A in sequence.
−2, −−−−−−, A−M subdivision, and the subdivisions constituting the second set are B−1, B-2 -−−−−, B−N subdivision in sequence,
This purification zone and each subdivision have a front end and a rear end, and every other A-type subdivision and B-type subdivision are installed in the purification subdivision in the direction from the front end to the rear end, and thus a certain A-type subdivision The front end and the rear end of are connected to the front end of the front B-type partition and the front end of the succeeding B-type partition, respectively, and one A-type partition and the following B-type partition are combined into one processing stage (Processing Stage). ) Is formed, and the raw material mixture and the first washing liquid are introduced into the front end and the rear end of the purification zone, respectively.
A crystal and a liquid exist in each compartment, and in each compartment, a two phase mixture and an intercrystal space
ine space) and a part of the liquid in each compartment becomes a free liquid (Free liquid), and the rest is a retained liquid (Retaine
d)) in (a) Type A section, a solid stirrer with a stirring blade is crossed within a narrower range from the front end to the rear end of the purification section. The first step to enhance the transfer of impurities in each subdivision from the stagnant liquid to the free liquid by local agitation, (b) Backwash operation (Counterwashing) or densification operation (Compaction) in type B subdivision Or, by combining both operations,
The second stage of reducing the amount of impurities from the free space between crystals, (c) the third stage of moving the solid phase from the front end to the rear end of the purification zone, and (d) the majority of the free space passing through the division. It also includes the fourth step of continuously transporting the liquid from the rear end to the front end of the purification zone, and further (i) the amount of mother liquor transported from the front end to the rear end of the inlet of each type B partition is the amount of crystals transported together. And (ii) the spaces between crystals in most of the A-type and B-type compartments are almost completely filled with liquid to form a sub-merged bed. How to purify. 2. The method according to claim 1, wherein, in the third step, the solid phase is transported from the front end to the rear end through a large number of sections. 3. The method of claim 1 wherein the third step is accomplished by changing the feed points of the feed mixture and the primary wash liquor. 4. A process according to claim 2 in which the first component is the solvent of the mixture and the first washing liquor used is the substantially pure first component. 5. The two-phase mixture in the B-type compartment forms a dense bed, the density of which is higher than that of the naturally formed bed, and the B-type operation is achieved by a backwash operation. Method. 6. The method according to claim 2, wherein the ratio of the amount of the mother liquor to the crystals in each A type fraction is smaller than 2: 1. 7. The amount ratio of the mother liquor and the crystals in each B-type compartment is 2: 1.
The method of claim 2 which is less than. 8. The method according to claim 2, wherein the B-type partition is divided by a partition plate so that the stirring action in the adjacent A-type partition does not significantly agitate the crystal bed in the B-type partition. 9. A B-type partition and an A-type partition are directly connected to each other, and B
The crystal bed in the mold zone is subjected to the force applied to the front end of the purification zone and the force of gravity coming from the zones above this zone, so that the compactness is much higher than the naturally formed compactness. The method according to any one of claims 2 to 8. 10. The B type section and the A type section are separated by one movable perforated plate, and the static bed in the B type section is compressed by a movable pressurizer. The method of any one of the paragraphs. 11. The method according to claim 10, wherein the movable pressurizer and the perforated plate are integrated. 12. The B-shaped section and the A-shaped section are connected by a fixed plate, and the crystal bed in the B-shaped section is compressed by a movable pressurizer. One way. 13. The method according to any one of claims 2 to 8, wherein the A-type section is agitated by an agitator having an operation method which is almost on the same plane. 14. The method according to claim 13, wherein the stirrer is connected to a rotator, so that the stirrer has a rotational movement. 15. A method according to any one of claims 2 to 8 wherein the transport of the solid phase is carried out by a scraping or shaving method by means of a movable leaf. 16. The B-type partition further comprises a solid transport partition and a liquid transport partition, and most free liquid is transported in the direction from the rear end to the front end of the purification zone bypassing the stationary phase transport partition. The method according to any one of claims 2 to 8. 17. The type A section further comprises a solid phase transport section and a liquid phase transport path, and most free liquid bypasses the solid phase transport section and is transported from the rear end to the front end via the liquid phase transport path. The method according to any one of claims 2 to 8, wherein the method is performed. 18. The method according to any one of claims 2 to 8, wherein two or more processing stages are included in one container. 19. The purification area has one or many plates.
9. A method according to any one of claims 2-8, wherein the plate column comprises a plate column with one A-type section on one or a number of plates in the column. 20. The method according to claim 19, wherein the A type partition is a horizontal partition and the solid phase and the liquid phase are transported in a relative direction on a substantially horizontal plane. 21. The method according to claim 20, wherein the A-type compartment is circular and the solid phase and the liquid phase are transported in the radial direction inward and outward in relative directions. 22. The A-type operation and the B-type operation are simultaneously performed in one section, and the A-type operation is achieved by ultrasonic vibration acting in a transverse direction. Item 9. A method according to any one of items 8 to 8. 23. The A-type operation and the B-type operation are simultaneously carried out in one section, and the A-type operation is carried out by a stirrer having a small cross-sectional area in the direction perpendicular to the traveling direction, such as a thin line or a thin blade. The method according to any one of claims 2 to 8, wherein the method is performed. 24. The A-type operation and the B-type operation are simultaneously performed in one section, and the A-type operation is performed by mixing the two-phase mixture with a static mixer (St.
A method according to any one of claims 2 to 8, which is achieved by passing through an atic mixer. 25. A method of washing an impure crystal containing a mother liquor with a washing liquid in one purification zone to obtain a residue containing a purified crystal and an impure solute, wherein the crystal is a nearly pure first component. Yes,
The mother liquor contains the first component and one or more solutes, and the purification section is composed of two groups of A-type and B-type compartments, and the first group of compartments are sequentially A-1, A- 2, −−−−
-, A-M subdivision, and the subdivisions of the second set are sequentially B-1, B-
2, −−−−−, B−N subdivisions, each of the purification subdivisions and each subdivision has a front end and a back end, and the A type subdivision and the B type subdivision are alternately arranged from the front end to the rear end. It is installed in the purification zone, and thus the front end and the rear edge of a certain type A section are connected to the rear edge of the previous B type section and the front edge of the succeeding B type section, respectively.
One processing step (Pr
, the solid and liquid mixture raw material and the first washing liquid are introduced into the front end and the rear end of the purification zone, respectively, and a certain amount of crystals and a certain amount of liquid are present in each zone and within each zone. In the method in which a two-phase mixture and an inter-crystal space exist, a part of the liquid is a free liquid and the rest is a retained liquid, (a) the two B-type fractions (B-n fractions) Depleting most of the intercrystalline free liquid from the phase mixture to reduce the amount of impurities in the intercrystalline free space and to deplete the intercrystalline free space from the Bn partition containing the vapor phase and mother liquor A first stage for discharging a drained calse (K _B ) _n , (b) a second stage for immersing the depleted lumps of each type A section in a washing liquid to transfer impurities in the retained liquid to a free liquid, (c) ) The third stage, in which the solid phase is sequentially passed through each section and transported from the front end to the rear end of the purification section, (d) The free liquid is sequentially passed through each section. A purification method, including a fourth stage for transporting from the rear end to the front end of the purification zone. 26. The solid phase discharged from A-n partial ku (K _{A) n} is depleted in B-n partial wards, the solid phase (K _{B) n} and a mother liquor (I _{B) n}
Then, a part of the mother liquor becomes the inter-stage transport liquid (L _B ) _n , and the remaining part (J _B ) _n becomes the intra-stage circulating liquid.
-The method according to claim 25, wherein the method is carried out by dividing into n sections. 27. The method of claim 25, wherein the first component is the solvent of the liquid mixture and the first wash used is also a substantially pure first component. 28. The method of claim 27, wherein the cleaning step is a batch-wise operation and includes an A-type operation that operates a dipping operation and a B-type operation that operates a depletion operation. 29. The method according to any one of claims 25 to 28, wherein the crystal depletion operation is achieved by moderate centrifugation. 30. The method according to any one of claims 25 to 27, wherein the crystal depletion operation is accomplished by using a packed bed of crystals of suitable height. 31. The method of claim 29, wherein the processing stage is in a rotating cylinder rotated at a suitable initial velocity (rpm) ₁ . 32. Transport of at least a portion of the solid phase is accomplished by a transfer means rotated at a second speed (rpm) _2, which speed is either higher or lower than the first speed. A method as claimed in claim 29. 33. The solid phase and the liquid phase in the A-n section are stirred by a stirring means rotating at a second rotation speed (rpm) ₂ , and the rotation speed is higher or lower than the first rotation speed. The method of claim 29, wherein the method is: 34. Further, (a) the treatment zone is an upright zone, (b) the mixed feed is introduced from the lower end of the purification zone, and (c) the two-phase mixture is contained in most of the A and B type zones. In the dry bed (d
(d) The solid phase is pushed up by the moving blades, and (e) most of the B-type compartments are interspersed with the solid walls and the two-phase mixture in it. 28. The method according to any one of claims 25 to 27, characterized in that it is prevented from being excessively agitated by the agitating means in the adjacent type A section. 35. A method for obtaining a residue containing purified crystals and impurities by washing a mixed feed with a certain amount of a first washing liquid in a batch process in a purification zone containing at least one crystal washing zone. Wherein the mixed feed contains crystals of the first component and a method comprising a liquid mixture containing the first component and impurities, (a) introducing a certain amount of the mixed feed into each washing section. , First floor
(K _{B) o} is formed and conducted a multistage washing operation first floor to form a (b) washing wards,
For example, in the nth stage, the solid phase (K _B ) _n-1 is placed and the washing liquid L _{n + 1} is used to emphasize the transfer of impurities from the retained liquid to the free liquid. B-type operation to reduce the amount of impurities in the space and washing the crystals to obtain a solid phase.
(K _B ) _n forms a liquid phase L _n , and the solid phase (K _B ) _n is (n + 1)
Subjected to the following washing step, the liquid phase L _n method characterized by comprising the steps used for (n-1) following washing operations. 36. The B-type operation is a draining operati
on), so the solid phase (K _B ) _n is the depleted solid phase (Drain
ed Solid Phase) and the A-type operation comprises a dipping operation. 37. The type B operation is a backwash operation, and the solid phase (K
The method of claim 35, wherein _B ) _n is a Submerged Solid Phase. 38. The method according to claim 36, wherein the mixed feed contains crystals of the first component and an aqueous solution, and the first washing liquid is an aqueous solution. 39. A crystal washing method having a front end and a rear end, wherein crystals are purified from a mixture of the crystals and the liquid with an initial washing liquid, comprising: (a) A-1, A-2, ----- , A set of agitated washing subzones consisting of A-M subdivisions, and within each subdivision there are a large number of agitating blade sub-pieces which are held on a solid material; (b) B-1, There is a set of non-stirring and washing subdivisions consisting of B-2, -----, and B-n subdivisions, and a partition plate is installed in each subdivision and the solid-liquid mixture contained is excessively agitated. (C) The above-mentioned divisions of both sets are installed in sequence from the front end to the rear end in sequence and at alternate intervals; (d) The solid phase is directed from the front end to the rear end, and the liquid phase is reversed. Transported from rear end to front end; Characterized crystal washing method. 40. A mixture of the crystal of the first component and the liquid of the first component and one or more impurities is washed with a certain amount of a first washing liquid to form a purified crystal and a residue containing the impurity. In the device, (a) the first set consisting of A-1, A-2, -----, and AM subdivisions, and B-1, B-2, -----, B in the device. -There is a purification zone that includes a second set of N zones, and each zone has a front edge and a rear edge, and every other A-type and B-type edge in the direction from the front edge to the rear edge. Installed in the purification zone, and the front and rear ends of the A-type partition are connected to the rear edge of the front B-segment and the front end of the succeeding B-type partition, respectively, and one A-type partition and the trailing B-type partition are connected. of forming a single process stage in combination, (b) incorporating the processing stage, comprising a rotary cylinder which is rotated at an appropriate first speed (rpm) _1, crystal and mixture supply fee and the first liquid Was introduced at the front end and the rear end of each purification District 滌液,
That is, a certain amount of crystals and a certain amount of liquid are present in each compartment, the two-phase mixture and intercrystalline space are present in each compartment, some of the liquid becomes free liquid, and the rest becomes stagnant liquid. And a member rotating at a second rotational speed (rpm) ₂ slightly faster or slightly slower than the first rotational speed for transporting at least a part of the solid phase.