JP2845489B2 - Regeneration method of mixed-bed sucrose liquid purification equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for regenerating a sugar solution refining apparatus for desalting and decolorizing a sucrose solution, and more particularly, to a method for mixing and using a cation exchange resin and an anion exchange resin. The present invention relates to a method for regenerating a bed-type ion exchange device.

(Prior art) The so-called reverse type two-bed column type apparatus for purifying a sucrose solution is to remove color and anions with a strongly basic anion exchange resin and then remove cations with a weakly acidic cation exchange resin. Although it is known and widely used industrially, there is a problem that the purity (electric conductivity) of the processing solution is not sufficient.

On the other hand, the regeneration operation is more complicated than that of the two-bed type apparatus, but as a sucrose solution purification apparatus that can obtain a processing solution with excellent purity, a strongly basic anion exchange resin and a weakly acidic cation exchange resin are mixed. There is known a mixed-bed apparatus used for such a purpose.

In a general sucrose solution purification process in which sucrose solution is passed through this mixed-bed type sucrose solution purification apparatus to perform desalting and decolorization, a sucrose solution treatment in which an ion exchange resin is regenerated every time a certain period of purification treatment is performed. Purification of the sucrose solution is carried out by repeated cycles of regeneration.

A typical regeneration process for mixed-bed type equipment is
Basically, it is different from the regeneration of the two-bed type device known in -24663 or the like.First, by backwashing or specific gravity separation, a high specific gravity cation exchange resin is placed in the lower layer, and a relatively small specific gravity anion exchange resin is used. After being separated into upper layers,
To regenerate the anion exchange resin, pass caustic soda solution downflow from the top of the tower while passing water upflow from the bottom of the tower to pass the spent caustic soda waste liquid to the middle height of the tower. Is discharged from the water collecting device (collector) placed outside the basin to regenerate the anion exchange resin in the upper layer. Drain from the collector through to regenerate the lower cation exchange resin, and after this, wash water is passed from the top and bottom of the tower,
The cleaning water is discharged from the collector to complete the regeneration process.
Thereafter, an operation is performed in which both resins are mixed to prepare for the next sugar solution treatment.

In addition, since the performance of the ion exchange resin gradually decreases due to repeated use of the ion exchange resin of the sucrose liquid purification device,
It is common practice to perform a regenerative treatment with hydrochloric acid every several tens of cycles from the sugar solution treatment to the regeneration to recover the anion exchange resin having deteriorated performance.

The reason why the performance of the ion exchange resin is reduced is considered as follows. That is, in the sucrose solution to be treated introduced into the mixed-bed ion exchange resin tower, decomposed glucose and fructose are also slightly mixed, and these sugar molecules are further decomposed in an alkaline state and undergo complicated changes. Generates organic acids, which are adsorbed on the ion exchange resin. This adsorption occurs especially in anion exchange resins,
There is a property that it is hard to be detached from the anion exchange resin only by the ordinary regeneration treatment.

For this reason, when the cycle of sugar solution treatment-regeneration is repeated, organic acids and the like adsorbed on the anion exchange resin accumulate, and the adsorption state gradually becomes stronger, irreversibly contaminates the ion exchange resin, and the purification capacity is reduced. Results.

Therefore, after repeating a cycle of regeneration-sugar treatment for a predetermined cycle (usually several tens of cycles), the regenerative treatment is performed to remove and wash the organic acids and the like adsorbed on the anion exchange resin. .

(Problems to be Solved by the Invention) Meanwhile, in the operation of regenerating the ion exchange resin and repeating the purification treatment of the sugar liquid by the conventional method of the mixed-bed purification device as described above, the step of concentrating the purification treatment solution is performed. However, there is a specific problem that coloring of the purified liquid appears in the two-bed system. According to the investigations of the present inventors, it has been found that this coloring is caused by NaOH eluted in the treatment solution. This is because a part of the cation exchange resin remains in the form of R-Na during the regeneration treatment, and this is It is presumed that hydrolysis occurs during the purification of sugar solution, leading to elution of NaOH.

A part of the cation exchange resin remains in the form of R-Na in the conventional regeneration method of the mixed-bed purifier described above for the following reason. That is, as already known, in the process of sugar solution treatment, the cation exchange resin gradually swells with the progress of ion exchange, and shrinks due to regeneration treatment,
Swelling is eliminated. Therefore, due to the swelling and shrinking, the volume of the lower layer cation exchange resin fluctuates between the start and the end of the regeneration treatment, and the boundary between the upper layer and the lower layer fluctuates. For this reason, two layers of an anion exchange resin and a cation exchange resin are usually provided for a collector fixed at a predetermined height in the ion exchange tower based on the volume of the cation exchange resin in the swelling eliminated state (contracted state). The heights of the boundaries of these resins at the start of the separated regeneration do not match, indicating that the swollen cation exchange resin exists above the collector position.

In this state, if the cation exchange resin is first regenerated and then the anion exchange resin is regenerated, some cation exchange resins located above the collector are not sufficiently contacted with hydrochloric acid, and the collector is not recharged. A small amount of cation exchange resin remains on the upper side. Then, when the NaOH solution is passed through the upper anion exchange resin for regeneration of the anion exchange resin, the NaOH solution comes into contact with the remaining cation exchange resin on the upper side of the collector, and the cation exchange resin reacts with the above-mentioned R.
It was found that the result was a state of -Na.

Even if the NaOH solution is first passed through the upper layer and then the hydrochloric acid is passed through the lower layer, the problem that the swelling of the cation exchange resin is not completely eliminated remains, and the above-mentioned difficulty cannot be solved.

In order to solve this problem, the height of the collector inside the ion exchange tower may be set in advance to a height expected as a boundary position when the cation exchange resin swells. This substantially guarantees contact of the hydrochloric acid with the total cation exchange resin. However, on the other hand, in this case, the contraction proceeds by passing the drug through the cation exchange resin, and as the swelling gradually disappears, the boundary with the anion exchange resin will be located below the collector, and the At the end of the regeneration treatment of the exchange resin, a part of the anion exchange resin enters the lower side of the collector. Then, the anion exchange resin in this portion comes into contact with the hydrochloric acid solution and cannot come into contact with the NaOH solution after the regeneration treatment, resulting in poor regeneration. As a result, even with this method, good regeneration treatment cannot be realized.

Due to the above problems, the present invention provides good regeneration of a cation exchange resin that cannot be solved by the conventional regeneration method, particularly elution of NaOH into a purified solution due to R-Na remaining in a part of the cation resin. It is an object of the present invention to provide a regenerating method that solves the above problem and does not cause a regenerating failure of the anion exchange resin.

(Means for Solving the Problems) A method for regenerating a mixed-bed type sucrose solution refining apparatus of the present invention which achieves the above-mentioned object comprises a mixed-bed type sucrose solution purifying apparatus for each cycle of sucrose solution purification. In the regeneration treatment in which the strongly basic anion exchange resin and the weakly acidic cation exchange resin are separated from each other, the weakly acidic cation is passed by passing hydrochloric acid through both the strongly basic anion exchange resin in the upper layer and the weakly acidic cation exchange resin in the lower layer. It is characterized in that after regenerating the exchange resin, the regenerating solution is passed through the strongly basic anion exchange resin.

The passing of hydrochloric acid through both resins may be simultaneous or sequential, and the direction of the passing of the hydrochloric acid is not limited, but for convenience of operation, it is supplied from the upper part of the resin tower, and the upper layer and the lower layer are supplied. It is preferable that the resin is discharged from the lower part of the tower through the resin.

(Action) According to the method of the present invention, the hydrochloric acid solution is reliably brought into contact with all of the cation exchange resin swelling above the collector to eliminate the swelling, and thereafter, the method is limited to the upper anion exchange resin. The cation exchange resin in the state of R-Na remains in a part of the lower layer cation exchange resin after regeneration, which has been a problem in the conventional regeneration method, because regeneration with the NaOH solution can be reliably performed. The problem of having gone away.

In addition, hydrochloric acid is passed through the anion exchange resin every time the regeneration treatment is performed alternately with the sugar solution treatment.
The treatment corresponding to the conventional regeneration of the anion exchange resin, which was performed at the rate of the number of times, is given for each regeneration treatment. As a result, there is a problem of contamination of the anion exchange resin due to organic acid adsorption and deterioration of the performance over time. It is greatly eased, and the processing capacity of sugar solution purification by ion exchange resin is greatly improved as compared with the conventional method.

The ion exchange resin used in the present invention is a conventionally known strong basic anion exchange resin used for purification of sucrose (for example, Amberlite (registered trademark))
IRA-402BL, IRA-900, IRA-411S, XT-5007, Diaion (registered trademark, the same applies hereinafter) PA312), weakly acidic cation exchange resin (for example, Amberlite IRC-76, IRC-50, Levatit (registered trademark, The same applies hereinafter) CNP-80, Diaion W
K11) can be used.

Other operations except for the method of passing the regenerating solution, which are characterized in the present invention, for example, operations such as separation and mixing of both resins can be performed in the same manner as the conventional regeneration operation.

(Effect of the Invention) According to the regeneration method of the present invention, hydrochloric acid is passed through both the strongly basic anion exchange resin and the weakly acidic cation exchange resin to eliminate the swelling of the weakly acidic cation exchange resin. Rate) is improved, and problems such as coloring during concentration are eliminated. In other words, in the conventional method, since the swelling of the cation exchange resin cannot be completely eliminated, a part of the cation exchange resin remaining above the collector position remains in the form of R-Na. During the sugar solution purification treatment, Na was eluted into the treatment solution due to hydrolysis, and there was a problem that the purity (electric conductivity) was reduced and the treatment solution was colored. However, according to the method of the present invention, this problem is solved. Was.

In addition, the problem that the organic acid generated by the sugar decomposition was adsorbed on the anion exchange resin and gradually became difficult to be desorbed and firmly adhered to the resin, resulting in the deterioration of the ion exchange performance, was considered as a problem with hydrochloric acid in each regeneration treatment. Of the anion exchange resin is significantly reduced as compared with the conventional one, and this, combined with the sufficient regeneration of the cation exchange resin described above, improves the purification efficiency of the sucrose solution. There is an effect of improving.

(Examples) Hereinafter, the present invention will be described in detail based on examples.

Example 1 Sucrose solution (stock solution: B × 50, electric conductivity 220 μS / cm (25
℃)), strongly basic anion exchange resin (Amberlite
(IRA-402BL) 200 ml and a mixed bed filled with a weakly acidic cation exchange resin (Amberlite IRC-75) 100 ml under the following conditions to purify the sugar solution, and then regenerate under the following conditions. The operation was performed as one cycle.

First, as a regeneration treatment, 200 ml of 1N hydrochloric acid solution
Is discharged from the upper part of the resin cylinder in a downward flow manner, the waste liquid is discharged from the lower part of the resin cylinder, the anion exchange resin is treated with a hydrochloric acid solution, and the cation resin is regenerated. At the same time, the medicine was passed down in a downflow manner, and at the same time, water was allowed to flow through the lower part of the resin cylinder in an upflow manner, and the wastewater was discharged from a collector (collection pipe) installed at the separation position of the ion exchange resin. After the passing of the sodium hydroxide, the sodium hydroxide was switched to water only, and extrusion washing was performed to discharge excess chemicals. Then, the anion exchange resin and the cation exchange resin were mixed so as to be uniform. .

Thus, the sucrose solution is placed at 40 ° C.
The solution was passed at a flow rate of 600 ml / h.

In the flow-through treatment, a point at which the electric conductivity became 1 μS / cm (25 ° C.) or more was defined as a through-flow point.

FIG. 1 shows the relationship between the operation cycle and the processing capacity of the mixed-bed processing apparatus.

As can be seen from FIG. 1, the processing amount in one cycle was about 8 (40 times the amount of the anion resin used), and no reduction in the processing amount was observed even when the cycles were repeated.

Comparative Example 1 The operation of sugar solution treatment-regeneration was repeated in the same manner as in Example 1 except that the regeneration treatment was performed in the following manner in accordance with the conventional method, and the results are shown in FIG.

First of all, as the regeneration process, caustic soda 1N solution
At 45 ° C, 400 ml of the drug is passed down through the upper part of the resin cylinder at a rate of 600 ml / h, and water is passed through the lower part of the resin cylinder at a rate of 300 ml / h in an upward flow manner. The resin was discharged from a collector (liquid collection tube) installed at the separation position of the ion exchange resin.

Next, 200 ml of a 1N hydrochloric acid solution was passed through the lower part of the resin cylinder in an upflow manner, and water was passed from the upper part of the resin cylinder in a downflow manner, and drainage was similarly discharged from an intermediate collector.

As shown in FIG. 1, according to the conventional regeneration processing, the processing amount decreases as the operation cycle is repeated.

Example 2, Comparative Example 2 The purified solution obtained in Example 1 and Comparative Example 1 was
The solution was concentrated in vacuo at 70 ° C. using a rotary evaporator made of hard glass.

 As a result, the concentration results as shown in Table 1 were obtained.

Example 3 and Comparative Example 3 Changes in the pH of the treatment solution during the fifth cycle of the sugar solution treatment of Example 1 and Comparative Example 1 were measured, and the results are shown in FIG.

As can be seen from the results in FIG. 2, the average pH in the fifth cycle was 6.9 when the processing solution of the 40-fold volume treatment was collected according to the method of the present invention, whereas the average pH in the conventional method was 5%. Showed pH 8.3.

[Brief description of the drawings]

FIG. 1 is a comparison diagram of the amount of treatment per cycle in Example 1 and Comparative Example 1, and FIG. 2 is a graph showing a change in treatment solution pH in Example 3 and Comparative Example 3.

Claims (2)

(57) [Claims] In a regeneration treatment in which a strongly basic anion exchange resin and a weakly acidic cation exchange resin are separated in a mixed-bed sucrose solution purification apparatus in each cycle of a sucrose solution purification process, Hydrochloric acid is passed through both the basic anion exchange resin and the underlying weakly acidic cation exchange resin to regenerate the weakly acidic cation exchange resin, and then the regeneration solution is passed through the strongly basic anion exchange resin. A method for regenerating a mixed-bed sucrose liquid purifying apparatus. 2. The method according to claim 1, wherein the passing of the hydrochloric acid is carried out from the upper portion of the separated strongly basic anion exchange resin in the upper layer and discharged from the lower portion of the weakly acidic cation exchange resin in the lower layer. 2. The method for purifying a mixed-bed sucrose solution according to 1.