JPS5940064B2 - How to regenerate ion exchange resin layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a weakly basic anion exchange resin layer used in a starch sugar refining process and whose function has been reduced.

Currently commercially available forms of starch sugar include starch syrup, powdered starch syrup, crude glucose, crystalline glucose, and high-fructose high fructose, but these sugars have a particularly delicate flavor because they are less sweet than sucrose. It is widely used in foods.

During the production process of starch sugar as described above, there is a step in which a saccharifying enzyme or acid is applied to the starch solution to saccharify the starch.
The aqueous solution containing starch sugar obtained at that time (hereinafter referred to as starch sugar solution).

) contains impurities such as salts, colored substances, and organic substances.

Therefore, as a method for purifying starch sugar solution to remove these impurities, an ion exchange resin method is generally adopted in which impurities are removed using a cation exchange resin and an anion exchange resin.

As the anion exchange resin employed in this case, a weakly basic anion exchange resin having a low basicity is usually used.

To regenerate the weakly basic anion exchange resin layer, which was conventionally used for these purifications and whose functionality has decreased, a parallel-current regeneration method is adopted in which it is regenerated by flowing it in the same downward flow as the downward flow of starch sugar solution. has been done.

On the other hand, as a method for regenerating an ion exchange resin layer, in addition to the above-mentioned co-current regeneration method, a counter-current regeneration method in which the direction of liquid flow and the flow direction of the regenerant are opposite to each other is generally known.

However, in this method, since the regenerant is passed in an upward flow from the lower part of the ion exchange resin column, the ion exchange resin is disturbed, that is, the so-called ion exchange resin layer is disturbed when the regenerant is distributed.

Therefore, a means for regenerating the ion exchange resin layer while preventing it from becoming fluidized is required.As one method for preventing the fluidization of the ion exchange resin, an intermediate collector is buried slightly below the top surface of the ion exchange resin layer. When flowing the regenerant from the bottom of the ion exchange resin layer in an upward flow, pressurized water or pressurized air is introduced from the top of the ion exchange tower, and the pressurized water or air is discharged from the intermediate collector together with the recycled waste liquid, A method has been adopted in which the ion exchange resin layer is regenerated while stably maintained by introducing pressure of pressurized water or pressurized air.

In the countercurrent regeneration method, the regenerated resin layer is always completely regenerated near the inlet of the regenerant, and incompletely regenerated near the outlet.

If raw water is passed through the resin layer in this state from the incompletely recycled resin to the fully recycled resin using a countercurrent method, even if the ions adsorbed on the incompletely recycled resin leak into the processing solution, It is immediately adsorbed on the completely regenerated resin, and a highly pure processing liquid can be stably obtained.

Therefore, when using the same regenerant, the countercurrent regeneration method has been increasingly adopted in recent years because it improves the regeneration efficiency, ie, the equivalent basis ratio of the amount of regenerant used to the amount of ions that can be exchanged.

However, if a countercurrent regeneration method is adopted in which a starch sugar solution is passed through a weakly basic anion exchange resin layer in a downward flow and then a regenerant is passed in an upward flow from the bottom of the resin layer, the ion exchange resin layer Fine bubbles are generated near the intermediate layer, and these adhere to the ion exchange resin, causing fluidization of the ion exchange resin layer and uneven flow of the regenerant, resulting in highly efficient regeneration, which is a feature of countercurrent regeneration. There was a drawback that it could not be done.

The present inventors conducted various studies in order to solve the above-mentioned drawbacks regarding the countercurrent regeneration method of the weakly basic anion exchange resin layer used in the purification of starch sugar solution. Although it is not clear why fine bubbles are generated, the present invention has been completed based on the discovery that the generation of fine bubbles can be prevented to an almost imperceptible extent.

That is, in the present invention, a starch sugar aqueous solution is passed in a downward flow from above a weakly basic anion exchange resin layer, and when the function of the ion exchange resin layer decreases, water is passed from the bottom of the ion exchange resin layer. Alternatively, the ion exchange resin layer is stirred and mixed by introducing air, and then allowed to settle, and then a regenerating agent is passed in an upward flow from the bottom of the ion exchange resin layer to regenerate the ion exchange resin layer. The gist of the present invention is a method for regenerating an ion exchange resin layer characterized by the following.

The present invention will be explained in detail below.

First, the ion exchange resin layer, where the function of the ion exchange resin has been reduced by passing the starch sugar solution in a downward flow, is passed through water to replace the starch sugar solution remaining in the layer with water, and then undergoes a regeneration process. Move.

As a method for passing the regenerating agent, a countercurrent regeneration method is adopted in which the regenerating agent is passed in an upward flow, which is opposite to the direction in which the starch sugar solution is passed.

In the regeneration process of the present invention, first, the ion exchange resin layer is stirred and mixed in order to disperse the weakly basic anion exchange resin that has adsorbed impurities in the layer and make the ion exchange resin layer uniform.

Stirring and mixing is performed by passing water or air from the bottom of the ion exchange resin layer.

In the case of water, the flow conditions are such that the ion exchange resin layer can be fluidized and mixed, and although it depends on the water temperature, a flow rate of 5 to 8 m/hr is usually employed.

Stirring with water is advantageous because it can be replaced by a normal backwashing step for cleaning the ion exchange resin layer.

Further, in the case of air, the flow pressure and amount are not particularly limited, but may be as long as the ion exchange resin layer can be sufficiently mixed with fluid agitation.

Furthermore, stirring with water and stirring with air may be used in combination, for example, stirring with air and then stirring with water.

The above-mentioned stirring time may be about 5 to 15 minutes.

Next, after the stirred and mixed weakly basic anion exchange resin layer is allowed to settle, pressurized water or pressurized air is introduced from the top of the tower to prevent fluidization of the ion exchange resin layer. At the same time, a regenerating agent is passed in an upward flow from the lower part of the ion exchange resin layer to regenerate the ion exchange resin layer.

By carrying out the present invention, even when the regenerant is passed in an upward flow through the agitated and mixed weakly basic anion exchange resin layer, the generation of air bubbles is hardly observed, and therefore the floating and fluidization of the ion exchange resin layer is prevented. It doesn't happen.

Therefore, an efficient countercurrent regeneration method can be performed.

The weakly basic anion exchange resin used in the present invention includes:
Examples of the ion exchange group include those having various amine groups below a tertiary amine group, or those having a mixture of ammonium groups and various amine groups.

A typical commercially available product is Diamondion [F]WA3.
0, Amberlight [F] IRA-93, Revachit (
Examples include BIMP64, and porous types are suitable.

As described above, according to the method of the present invention, a countercurrent regeneration method is adopted in which a starch sugar solution is passed in a downward flow and a regenerant is passed in an upward flow to the weakly basic anion exchange resin layer whose function has decreased. However, it can be played back efficiently.

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to the following examples.

Example 1 Column Dimensions Three transparent vinyl chloride columns with an inner diameter of 20α and a height of 300 cIrL were prepared, two of which were equipped with an intermediate collector at a position 125 cm from the bottom end of the column.

Each of the above columns was packed with 47 g of a weakly basic anion exchange resin, Diaion [F]WA30.

A starch sugar solution having the composition shown in Table 1 after being treated with a strongly acidic cation exchange resin was passed through each of the weakly basic anion exchange resin layers in parallel in a downward flow.

The liquid was passed through each column at a rate of 188 t/hr, at a temperature of 30° C., and in an amount of 200 (l), and after the starch sugar solution remaining in the layer was replaced with water, each column was regenerated.

First, regarding the column equipped with an intermediate collector, one column adopts the method of the present invention, so air is introduced from the bottom of the ion exchange resin tower before the regenerant is distributed, and after stirring and mixing for 5 minutes, water is added at a rate of 5 m/hr. The mixture was introduced at a flow rate, stirred for 100 minutes, and allowed to stand to settle the resin layer.

The other column with an intermediate collector did not mix the weakly basic anion exchange resin layer in order to employ the conventional countercurrent regeneration method.

A regenerant was passed through each of the columns prepared in this way, and countercurrent regeneration was performed under the same conditions.

That is, 3 m/hr from the top of the weakly basic anion exchange resin column.
While introducing pressurized water at a flow rate of 3 m/hr, 4% caustic soda was injected from the bottom of the ion exchange resin layer for 30 minutes at a flow rate of 3 m/hr, followed by demineralized water flowing at a flow rate of 3 m/hr for 40 minutes.

Both recycled waste liquid and pressurized water were discharged from an intermediate collector.

Next, demineralized water is introduced from the upper part of each ion exchange tower to wash the ion exchange resin layer with water at a flow rate of 450 t/hr downward, and the washing wastewater discharged from the lower part of the ion exchange tower is 10
I did this until I got the following.

On the other hand, the column without an intermediate collector was regenerated using the conventional co-current regeneration method.

That is, after flowing 4% caustic soda from the top of the ion exchange tower at a flow rate of 3 m/hr for 30 minutes, demineralized water was flowed at a flow rate of 3 m/hr.
It was circulated for 40 minutes at r.

Next, demineralized water is introduced from the upper part of the ion exchange tower to wash the weakly basic anion exchange resin layer with water at a flow rate of 450 t/hr in a downward flow, and the washing wastewater is discharged from the lower part of the ion exchange tower.
This was repeated until the value was 10 or less.

Next, starch sugar solution 2000/1.
was passed through the chamber, and the electrical conductivity of the treatment solution at that time was measured.

The results are shown in FIG. In Figure 1, the horizontal axis is the amount of liquid passed (t), and the vertical axis is the electrical conductivity of the processing liquid (μS/cIrL).
In the figure, curve 1 shows the method of the present invention, curve 2 shows the conventional countercurrent regeneration method, and curve 3 shows the conventional cocurrent regeneration method.

Note that foaming in each ion exchange resin layer during the flow of the regenerant was hardly observed when the method of the present invention was adopted, but fine foaming was observed when the conventional countercurrent regeneration method and cocurrent regeneration method were used. Foaming was observed, and some fluidity of the ion exchange resin layer was observed.

Additionally, Diamond ion is a registered trademark of Mitsubishi Chemical Industries, Ltd.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an electrical conductivity curve, where the horizontal axis represents the flow rate (t), and the vertical axis represents the electrical conductivity of the processing liquid (μS/cn
Curve 1 is the electrical conductivity curve of the treated liquid obtained in Example 1, curve 2 is the conventional countercurrent regeneration method, and curve 3 is the treated liquid electrical conductivity curve obtained by the conventional cocurrent regeneration method.

Claims (1)

[Claims] 1. A starch sugar aqueous solution is passed in a downward flow from above the weakly basic anion exchange resin layer, and when the function of the ion exchange resin layer decreases, water or air is introduced from the bottom of the ion exchange resin layer. The ion-exchange resin layer is stirred and mixed, then allowed to settle, and then a regenerant is passed through the ion-exchange resin layer in an upward flow from the lower part of the ion-exchange resin layer to regenerate the ion-exchange resin layer. How to regenerate the exchange resin layer.