JPS6336834B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to the use of fruits and vegetables, seawater, salt water,
Apparatus and method for concentrating liquid mixtures, such as wastewater, chemical solutions and dispersions, by freezing a portion of a solvent, usually water.

BACKGROUND OF THE INVENTION It may become necessary to concentrate a liquid mixture by removing a portion of the solvent, usually water, from the liquid mixture;
At least sometimes it's desirable. The result is
It is in a concentrated state. Fruit juices and vegetable juices such as orange juice, grapefruit juice, grape juice, and tomato juice are usually concentrated by removing water through distillation. Furthermore, the condensation of seawater or salt water is also accomplished by distillation, but in this case the condensed steam is recovered as useful portable water, unlike the condensation of fruit and vegetable juices where the condensed steam is discarded. . In any case, each is a concentration process, and in the case of use, the concentrate is a necessary product, but in the case of obtaining portable water from seawater or salt water, the concentrate is discarded.

Distillation concentration as mentioned above, like the distillation of chemical solutions and liquid dispersions, relies on the latent heat of vaporization.
Requires a large amount of energy. At the temperatures used for distillation and concentration, it is inevitable that scale will form in the equipment and corrosion will progress. When food is distilled and concentrated, flavor and aroma may be lost.

In view of the aforementioned drawbacks of distillative concentration, it has been found advantageous to carry out freeze concentration for many products, especially those that utilize water as the liquid carrier. Freeze concentration generally requires less energy because it relies on heat of fusion instead of heat of distillation. In this process, water is removed by first forming ice crystals and separating them from the concentrate.
The ice crystals are then washed to remove any residual concentrate thereon. Throw away the ice crystals, or melt them if you need portable water.

It is difficult to completely remove concentrate from ice crystals during the washing process. When concentrating products such as orange juice, even a small amount of concentrate is lost due to fouling, which is economically undesirable.

See C. Judson King, The Separation Process, Mc Graw Hill, p. 725. As the size of the ice crystals increases, removal of deposited concentrate by washing becomes more effective. Reducing the viscosity of the product also makes it easier to clean.

US Pat. No. 4,091,635 discloses an apparatus and method for freeze concentrating a previously concentrated feed stream. The patent uses a two-stage system, with each stage using a freeze-crystallizer and a washing tank. 1st
In the stages, the concentration is doubled. Ice generated from the first stage is introduced into the second stage and diluted with a dilute feed stream. The diluted solution is then freeze concentrated in a second stage.

In none of the freeze concentrators described above, the concentrated liquid mixture is not recirculated through the freeze exchanger until a predetermined concentration is reached. Moreover, such recirculation systems have not been employed to produce relatively large size ice crystals or low viscosity ice slurries that are relatively easy to clean to eliminate residual concentrate.

SUMMARY OF THE INVENTION The present invention provides a cryogenic concentrator, a conduit for conveying a feed stream of an aqueous liquid mixture to the cryogenic concentrator, and a liquid mixture that is heated by heat exchange with a cryogenic liquid to form ice crystals within the liquid mixture. a conduit for supplying the liquid mixture from the cryoconcentrator to a freeze exchanger that indirectly cools the water; a device for supplying the ice crystal-containing liquid mixture from the freeze exchanger to the cryoconcentrator; A conduit for removing the liquid mixture from the tank, a device for removing the ice slurry from the cryoconcentrator and sending the ice slurry to the ice slurry washing tank, and a device for washing the ice slurry in the washing tank and collecting the ice and the aqueous mixture after washing. a conduit for discharging an aqueous mixture from a washing tank; and a device for discharging washed ice from the washing tank.

The conduit for removing the aqueous mixture from the wash tank may be provided with a conduit for conveying the aqueous mixture to the cryoconcentrator. The apparatus may also be provided with a melter for washed ice, a device for sending the washed ice from the washing tank to the melter, and a device for discharging water from the melter.

In order to make efficient use of the available cooling methods, the freeze concentrator includes a heat exchanger, a conduit through which a feed stream of the aqueous liquid mixture is delivered to a cryogenic concentrator, and a conduit that supplies the concentrated liquid mixture to the cryoconcentrator. and a conduit for passing cold water from the melter to a heat exchanger, opposite the flow of the feed stream, from the cryogenic concentrator, and a conduit for passing the cold water from the melter, opposite the flow of the feed stream, to the heat exchanger.

To facilitate ice crystal growth and reduce the viscosity of the ice slurry, the freeze concentrator includes a warm concentrator and a conduit that carries a feed stream of an aqueous liquid mixture to the warm concentrator, a cold concentrator and an aqueous liquid mixture. A conduit for transporting the liquid mixture from the warm concentrator to the low temperature concentrator, a conduit for supplying the liquid mixture from the low temperature concentrator to the primary freeze exchanger, and a conduit for heat exchange of the liquid mixture in the primary freeze exchanger with the low temperature liquid. a device for indirectly cooling and forming ice crystals in the liquid mixture; a device for feeding the ice-containing liquid mixture from a primary freezing exchanger to a cryoconcentrator; and a device for discharging the liquid mixture from the cryoconcentrator after freezing the water. a conduit for discharging the ice slurry from the cold concentrator and conveying the ice slurry to the warm concentrator; and a device for discharging the ice slurry floating in the liquid mixture from the warm concentrator and for ice washing the slurry a device for rinsing the ice slurry in the ice washing tank and collecting the washed ice and the aqueous mixture; a conduit for discharging the aqueous mixture from the ice washing tank; and a conduit for discharging the washed ice from the ice washing tank. A device will be provided.

A conduit may be provided for discharging the aqueous mixture from the ice wash bath to a warm concentrator. The device of the invention includes:
Furthermore, a melter for the washed ice, a device for conveying the washed ice from the ice washing tank to the melter, and a device for discharging water from the melter may be provided.

a heat exchanger and a conduit for supplying a feed stream of the aqueous liquid mixture through the heat exchanger to the warm concentrator, and a conduit for conveying the concentrated liquid mixture from the cold concentrator to the flow of the feed stream of the liquid mixture; Preferably, a conduit is provided to supply the heat exchanger. A conduit may be provided for supplying cold water from the melter to the heat exchanger, opposite the flow of the feed stream of the liquid mixture.

To control the temperature of the liquid mixture in the warm concentrator and to help obtain ice crystals of suitable size, the apparatus of the present invention includes a secondary freeze exchanger;
a conduit supplying the liquid mixture from the warm concentrator to a secondary freeze exchanger and ice to indirectly cool the liquid mixture by heat exchange with a cryogenic fluid to form ice crystals in the liquid mixture; A device may be provided for supplying the liquid mixture containing crystals from the secondary freeze exchanger to the warm concentration tank. Furthermore, the warm concentration tank may be provided with a heater to warm the liquid mixture therein as required.

When carrying out the invention as a method, an aqueous liquid mixture is fed to a cryoconcentrator, and the liquid mixture from the cryoconcentrator is fed to a freeze exchanger and cooled indirectly by heat exchange with the cryogenic fluid. Forming ice crystals in the liquid mixture, supplying the liquid mixture containing ice crystals from the freezing exchanger to the cryoconcentrator tank, discharging the liquid mixture from the cryoconcentrator tank after freezing the water, and removing the ice slurry from the cryoconcentrator tank. draining, feeding the ice slurry to the ice slurry washing tank, washing the ice slurry in the ice washing tank with water, collecting the ice and aqueous mixture after washing, discharging the aqueous mixture from the ice washing tank, and supplying the ice slurry from the ice washing tank after washing. A method is provided comprising: discharging ice.

The method according to the invention includes draining the aqueous mixture from the ice wash tank and sending the aqueous mixture to a cryogenic concentrator. This method supplies washed ice discharged from an ice washing tank to an ice melter,
This can be done in addition to draining the water from the ice melter.

In order to effectively utilize available cooling methods, the method of the present invention includes passing the aqueous mixture through a heat exchanger and then through a cryoconcentrator, and passing the concentrated liquid mixture from the cryoconcentrator into the feed stream. The feed stream may include passing the cold water from the melter through the heat exchanger opposite the flow of the feed stream.

Crystal growth and reduction of ice slurry viscosity are preferably obtained by introducing warm concentrate into the freeze concentration process. Furthermore, using a diluted solution (at a warm temperature) allows for the early production of large crystals. The method therefore comprises supplying an aqueous liquid mixture to a warm concentrator;
The aqueous liquid mixture is supplied from the warm concentrator to the low temperature concentrator, and the liquid mixture from the warm concentrator is supplied to the primary freezing exchanger, where it is indirectly cooled by a heat exchanger with the low temperature fluid and ice is added to the liquid mixture. The liquid mixture containing ice crystals is fed from the primary freezing exchanger to the cryoconcentrator, and after the water is frozen, the liquid mixture is discharged from the cryoconcentrator, the ice slurry is discharged from the cryoconcentrator, and the ice The slurry is supplied to a warm concentration tank, the ice slurry is discharged from the warm concentration tank, the ice slurry is sent to an ice slurry washing tank, the ice slurry is washed with water in the ice slurry washing tank, and the ice and aqueous mixture after washing is collecting and discharging the aqueous mixture from the wash tank and discharging the washed ice from the wash tank.

The method consumes less energy because it is based on the heat of fusion rather than the latent heat of vaporization. Because of the lower operating temperatures, it is less corrosive than distillation for processing many liquid mixtures. The present invention is believed to be suitable for handling a variety of liquids and a wide range of feed stream concentrates. It is a simple system and does not require complex feed pre-processing equipment.
Compared to the distillation method, scale generation and dirt are extremely reduced. Flavor and aroma are better maintained in the concentrate compared to distillation concentration methods.

The ice crystals formed in the process of the present invention are relatively large and exist in a low viscosity solution. The ice crystals are therefore easy to handle and cleaned free of deposits. Therefore, the melt water coming out of this process is
Virtually free of concentrates. For youth concentrators, this means less product is lost to the water leaving it.

The advantage of the two-stage process described above is that the concentration takes place at low temperatures and the ice is washed at warm temperatures. This is obviously beneficial for concentrating the youth, considering that ice from the youth cannot be washed at low temperatures.

DETAILED DESCRIPTION OF THE EMBODIMENTS In FIG.
is supplied to the heat exchanger 11 via. Liquid mixed streams include seawater, salt water, orange juice, grapefruit juice, grape juice, tomato juice, chemicals dissolved or decomposed in water, wastewater,
and other appropriately concentrated aqueous liquids. It goes without saying that such concentrates include preferred products such as fruit juice and vegetable juice.
There are also cases where the concentrate is discarded and ice or water is required, such as producing portable water from seawater or salt water.

The cooled liquid mixture exits heat exchanger 11 into conduit 14 and is fed from conduit 14 to cryogenic concentrator tank 16 . The liquid mixture is discharged from the lower part of the cryoconcentrator 16 through a conduit 18 leading to a pump 20. The ice content of the liquid mixture is low, but contains enough seed crystals to prevent the stream from overcooling. Via conduit 22, the liquid mixture is pumped 20 to freeze exchanger 24, where it is cooled by indirect heat exchange with a cooling fluid circulating through inlet conduit 26 and outlet conduit 28. Ru. Cooling fluids include refrigerants such as ammonia and Freon (trade name).
It may also be a pre-chilled liquid such as ethylene glycol or methanol. As the liquid mixture flows down through the freeze exchanger 24, its temperature drops sufficiently for ice to crystallize. As the flow progresses through the freeze exchanger 24, the ice fraction and crystal size increase and new ice crystals are formed. The ice-containing liquid mixture exits the freeze exchanger 24 and enters the cryoconcentrator 16, which operates substantially at the freezing temperature of the predetermined final concentrate. The ice slurry will float on top of the liquid mixture in the cryoconcentrator 16. Even if not floating, there will be a high concentration of ice crystals at the top of the liquid mixture. A vertically disposed baffle plate 30 within the cryoconcentrator 16 isolates the ice slurry to one side and prevents the ice from being discharged with the concentrate into the conduit 32. Conduit 32 communicates with pump 34, which in turn delivers the cryogenic concentrate to conduit 36. The cold concentrate passes through the heat exchanger 11 to the conduit 38
and conduit 38 supplies the cryogenic concentrate to the appropriate destination.

A downcomer 40 is disposed within the cryoconcentrator 16 and the height of the downcomer 40 is such that the ice slurry spills over the edge such that the ice slurry is discharged via a conduit 42 communicating with a pump 44. It's summery. The ice slurry is conveyed via conduit 46 from pump 44 to ice wash tank 48 where gravity separates the solution from the ice slurry. appropriately branching a portion of the feed stream from conduit 14 via conduit 12;
through valve 13 to conduit 46 and optionally
It may be used to dilute ice slurries or reduce their viscosity.

The ice cleaning tank 48 has a lower cleaning liquid receiving portion 50.
and an upper ice-receiving portion 52. A plurality of tubes 54 project upwardly from a plurality of outlets in the partition wall 49 . Hole 56 in tube 54
Accordingly, a feed stream is discharged from the ice receiving section 52, enters the tube 54, and enters the cleaning liquid receiving section 50. A conduit 58 conveys the cleaning liquid from the liquid receiving section 50 to the cryoconcentrator 16 by gravity or the use of a pump.

The upper part of the ice washing tank 48 is connected to the ice slurry melter 6
It is surrounded by a shell 60 forming an 8. Shell body 60
A motor 62 is mounted on top of the.
A shaft 64 extends from the motor 62 to a slowly rotating scraper blade 66. As the slurry porous bed of ice crystals rises in the ice cleaning tank 48 and its level increases, the rotating scraper blades 6
6 and the scraper blades 66 push the ice slurry over the edge of the ice washing tank;
Enter the ice melter 66 which includes a heating coil 69. A hot fluid is circulated through the heating coil, melting the ice and turning it into cold water. The heat required to melt the ice can also be obtained from the chiller of the freeze exchanger. For example, a melter can be used to concentrate refrigerant circulating through freeze exchanger 24. Chilled water exits ice melter 68 via conduit 70 and is sent to pump 72 . Conduit 74 pumps cold water 7
2 to the heat exchanger 11, and the hot water is sent to the heat exchanger 11.
through conduit 76.

The flow of chilled water is branched from conduit 74 through valve 78 to conduit 80 and the water is distributed over the porous ice slurry in ice wash tank 48 before the ice spills into ice melter 68. Thoroughly clean the ice.

Figures 2 and 3 illustrate a second embodiment of the present invention, which utilizes staged cold and warm concentrators to obtain staged crystallization. This is particularly useful for highly concentrated products. The staged crystallizer increases the crystal size and reduces the viscosity of the ice slurry entering the wash tank. The larger the crystals and the lower the viscosity, the more effective the cleaning. As shown in these figures, the liquid mixture feed stream passes through conduit 100 to heat exchanger 10.
2, from which the cryogenic liquid mixture stream enters conduit 10
4 to the warm concentration tank 106. The warm concentration tank 106 is substantially the space between the inner vertical wall 108 and the outer vertical wall 110. inner vertical wall 10
The space surrounded by 8 forms a low temperature concentration tank 111. A plate 112 forms the bottom of both thickeners.

A motor-driven sump pump 114 delivers the liquid mixture from the warm concentrator 106 to a conduit 116 that communicates with a valve 118 . Conduit 120 directs the liquid mixture to valve 11
8 to the neck of the freeze exchanger 122. As the liquid mixture descends through the freeze exchanger 122, it is indirectly cooled by heat release into the circulating cooling fluid. Cooling fluid is introduced into the freeze exchanger 122 via conduit 124 and discharged therefrom by conduit 126. Refrigerants such as ammonia or Freon gas, or ethylene glycol can be used as the cooling fluid. Other cooling fluids may be used to provide the desired refrigeration, if desired.

As the liquid mixture descending within freeze exchanger 122 cools, ice crystals form. The ice-containing liquid mixture is transferred from the bottom of the freeze exchanger 122 to a conical distributor 128 supported by scraper vanes 130.
flows into the nuchal region. A motor 132 is located within a dry well 134 formed by a cylindrical wall 135 located in the center of the cryoconcentrator 111 . A shaft 136 extends from the motor 132 to and drives the scraper blade 130.

An ice slurry is formed in the cryoconcentrator tank 111, with the ice slurry floating on top of the liquid mixture in the tank. The liquid concentrate is transferred to the cryoconcentrator tank 11 via conduit 138.
1, but a baffle plate 140 is provided to prevent ice slurry from entering the inlet of conduit 138. Conduit 138 conducts the cold liquid concentrate to heat exchanger 102 . The warmed liquid concentrate is discharged from the heat exchanger 102 via conduit 142 and sent to a destination for disposal or further processing as appropriate.

The liquid mixture is also passed through conduit 144 to cryogenic concentration tank 1.
11, with a baffle plate 146 at its entrance to prevent ice particles from entering conduit 144.
There is. Conduit 144 delivers the liquid mixture to pump 148 which leads to conduit 150. Conduit 150 delivers the liquid mixture to the upper portion of freeze exchanger 122;
The liquid mixture is then cooled and ice forms.
The liquid mixture containing ice crystals is then transferred to freeze exchanger 122
The liquid flows out from the bottom of the tank and enters the low-temperature concentration tank 111.

Once the ice slurry is formed in the cryoconcentrator tank 111,
The ice slurry contacts rotating scraper blades 130 and is forced up to the upper edge of wall 108 and enters warm thickener tank 106 containing a warm liquid mixture that dilutes the ice slurry, reduces its viscosity, and promotes ice crystal growth. promote,
Facilitates subsequent processing and cleaning.

The opening of the downcomer conduit 154 is connected to the warm concentration tank 1.
06 , which is fed to pump 156 and routed to conduit 158 .
Conduit 158 conveys the ice slurry to ice wash tank 160.
The ice cleaning tank 160 has a horizontal partition wall 162 that divides it into a lower cleaning liquid receiving section 164 and an upper ice receiving section 166. A plurality of tubes 168 project upwardly from the outlet of septum 162. Wash water exits ice receiving portion 166 through hole 170 in tube 168, enters tube 168, and enters wash liquid receiving portion 164. Conduit 170 supplies cleaning fluid from cleaning fluid receiving portion 164 to warm concentrator tank 106 .

The upper part of the ice washing tank 169 is connected to an ice melter 174.
It is surrounded by a shell 172 forming a . A motor 176 is mounted on top of the shell 172. A shaft 178 extends from the motor 176 to a scraper blade 180, which slowly rotates. As the level of the ice slurry rises in the ice cleaning tank, the ice slurry is removed by the rotating scraper blade 1.
Ice melter 174 with heating coil 182 in contact with 80 and pushed up over the edge of the ice wash tank
Enter. A hot fluid is circulated through the heating coil, melting the ice and turning it into cold water. Cold water is discharged from ice melter 174 via conduit 175 and sent to pump 177 . Conduit 184 conveys cold water from pump 177 to conduit 186. Conduit 186 supplies chilled water to heat exchanger 102 . Hot water is heat exchanger 1
02 via conduit 188.

A flow of chilled water is also routed from conduit 184 to conduit 190 and through valve 192 to conduit 194 from where water is sprayed onto the ice slurry in ice wash tank 160 and the ice overflows into ice melter 174. Thoroughly clean the ice before leaving.

It may be desirable or necessary to cool the liquid mixture in the warm concentrator 106, and therefore a secondary freeze concentrator 200 may be provided for this purpose. The flow of the liquid mixture is carried out in conduit 116.
branched from the freezing tank 2 by a conduit 202.
00, where the liquid mixture is indirectly cooled by heat exchange with the circulating cooling fluid. A cooling fluid, such as a refrigerant such as ammonia or Freon gas, is supplied through conduit 204 to freeze exchanger 200 and from there to conduit 2
06. Ice crystallizes from the liquid mixture during its descent through the freeze exchanger 200. The ice-containing liquid mixture flows out of the bottom of the freeze exchanger 200 into the warm concentrator tank 106 .

It may be desirable to increase the temperature of the contents of a warm concentrator. For this purpose, a heating coil 210, such as an electric heating coil or a hot fluid heating coil, can be provided.

The foregoing embodiments have been described only to facilitate understanding of the present invention, and are not intended to limit the present invention, and it will be obvious to those skilled in the art that various modifications may be made thereto.

[Brief explanation of the drawing]

FIG. 1 is an explanatory side view of a freeze concentrator of the present invention that utilizes a low temperature concentrator. FIG. 2 is an explanatory side view of the freeze concentration apparatus of the present invention, which utilizes a combination of a low temperature concentration tank and a warm temperature concentration tank. FIG. 3 is an explanatory plan view of the combination of the low-temperature concentration tank and the warm-temperature concentration tank shown in FIG. 2. 10,100...liquid mixture feed stream, 11,10
2... Heat exchanger, 16,111... Low temperature concentration tank, 2
4,122... Freeze exchanger, 38,142... Concentrate, 40,154... Downcomer, 48,160...
Ice cleaning tank, 66,130...Scraper blade, 6
8,174...Ice melter, 76,188...Water, 10
6... Warm temperature concentration tank, 128... Distributor, 140, 14
6... deflection board, 134... dry well.

Claims (1)

[Scope of Claims] 1. A cryoconcentrator, a conduit for supplying a feed stream of an aqueous liquid mixture to the cryoconcentrator, and a conduit for supplying a feed stream of an aqueous liquid mixture to the cryoconcentrator and for forming ice crystals within the liquid mixture by heat exchange with a cooling fluid. A device for supplying a liquid mixture containing ice crystals from a cryoconcentrator to a cryoconcentrator for indirect cooling; a device for supplying a liquid mixture containing ice crystals from a freeze exchanger to a cryoconcentrator; A conduit for discharging the concentrated liquid mixture from the cryoconcentrator, a device for discharging the ice slurry from the cryoconcentrator and sending the ice slurry to an ice slurry washing tank, and washing the ice slurry with water in the ice slurry washing tank. and a freeze concentrator comprising a device for collecting the washed ice and liquid mixture, a conduit for discharging the liquid mixture from the ice slurry wash tank, and a device for discharging the washed ice from the ice slurry wash tank. 2. The freeze concentration device according to claim 1, wherein the conduit for discharging the liquid mixture from the ice slurry washing tank is provided with a device for sending the liquid mixture to the low temperature concentration tank. 3. Claim 1, which is provided with an ice melter for ice after washing, a device for sending the washed ice discharged from the ice slurry washing tank to the ice melter, and a device for discharging water from the ice melter. Freeze concentrator as described in section. 4. A heat exchanger is provided to pass the feed stream of the aqueous liquid mixture through the heat exchanger and then to the low temperature concentrator, and the concentrated liquid mixture from the low temperature concentrator is combined with the feed stream of the liquid mixture. Freezing as claimed in claim 3, wherein the heat exchanger is passed oppositely, and the cold water from the ice melter is passed through the heat exchanger oppositely to the feed stream of the liquid mixture. Concentrator. 5. Before feeding the feed stream of the aqueous liquid mixture to the cryogenic concentrator, the feed stream of the liquid mixture is sent to the warm concentrator, and then the liquid mixture is transferred from the warm concentrator to the cold concentrator. Patent for delivering a feed stream and further delivering ice slurry to a warm thickening tank and from the warm thickening tank to an ice slurry washing tank before passing the ice slurry from the cold thickening tank to the ice slurry washing tank. A freeze concentration device according to claim 1. 6. A second freeze exchanger is provided and the liquid mixture is conveyed from the warm concentrator to the second freeze exchanger for indirect cooling by heat exchange with a cooling fluid so as to form ice crystals in the liquid mixture. 6. A freeze concentrator as claimed in claim 5, further comprising a conduit and a conduit for conveying the liquid mixture containing ice crystals from the second freeze exchanger to the warm concentrator. 7. A heat exchanger is provided so that the feed stream of the liquid mixture is passed through the heat exchanger and then supplied to the warm concentration tank, and the liquid mixture after concentration from the low temperature concentration tank is provided so as to face the flow of the liquid mixture. an ice melter for passing the ice through the heat exchanger and after washing, and a device for sending the washed ice discharged from the ice washing tank to the ice melter;
Freezing according to claim 5, characterized in that means are provided for discharging cold water from the ice melter, such that the cold water from the ice melter is passed through the heat exchanger opposite the feed stream of the liquid mixture. Concentrator.