JPH0380543B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a method for producing pure water using a mixture of anion exchange resins and cation exchange resins. This invention relates to a method for separating and extracting a certain amount of anion and cation exchange resin.

[Prior art]

In an ion exchange device that desalinates water using an ion exchange resin, the cation exchange resin and anion exchange resin used for desalination are regenerated in a regenerator and used again for desalination.

In the regeneration device, first, in a tank, the anion exchange resin mixture and the cation exchange resin mixture are backwashed to remove dirt, and the anion exchange resin and the cation exchange resin are separated into two layers due to the difference in specific gravity. The anion exchange resin in the upper layer is introduced into an anion exchange resin regeneration tower and regenerated with caustic soda, etc., and the cation exchange resin remaining in the tank is regenerated with sulfuric acid etc. in the tank, and then the regenerated resin are returned to the desalination tower and used for desalination. In the conventional method, after the anion exchange resin and the anion exchange resin are separated into two layers, the anion exchange resin is transferred to an anion exchange resin regeneration tower from a single resin extraction pipe installed near the separation surface of both resins. However, during backwashing, when the anion and cation exchange resins are separated into two layers, they are completely removed.
It is difficult to separate the layers, both resins exist in a mixed form near the separation surface, and the separation surface shifts vertically depending on the state of resin transfer from the demineralization tower.
Therefore, when extracting the upper anion exchange resin from a single extraction pipe installed near the separation surface, the cation exchange resin may also be extracted, and only the anion exchange resin may be completely extracted. It may remain in the cation exchange resin without being released. In this case, the cation exchange resin extracted together with the anion exchange resin is reversely regenerated with caustic soda in an anion exchange resin regeneration tower, and the anion exchange resin remaining in the cation exchange resin is reverse regenerated with sulfuric acid. It is predicted that the ion exchange capacity will decrease and the sulfate ions or sodium ions used to regenerate the ion exchange resin will leak downstream into the water flowing through the demineralization tower, adversely affecting the water quality of the primary system. .

As a method to solve this problem, there is a method of using an ion exchange resin for separation and supplementation and separating both negative and positive ion exchange resins using two resin extraction tubes (Japanese Patent Application Laid-open No. 56-38136). (see official bulletin). This conventional method will be explained based on FIG.

In FIG. 1, 1 is a cation exchange resin layer; 2 is a cation exchange resin layer;
is an anion exchange resin layer, 3 is a mixed ion exchange resin layer, 3' is a separation surface between anion exchange resin and cation exchange resin, 5 is a cation exchange resin regeneration tower, 6 is a backwash water introduction pipe, and 7 is a An air inlet pipe, 8 a resin inlet pipe from the demineralization tower, 10 an anion exchange resin outlet pipe,
11 is a mixed ion exchange resin extraction pipe, 12 is an anion exchange resin regeneration tower, 13 is an ion exchange resin tank for separation and replenishment, 14 is an air introduction pipe, 15 and 16 are sluicing water introduction pipes, 17 is a separation and replenishment cation Replacement resin transfer pipe, 18 is overflow pipe, 19
2 indicates an anion exchange resin transfer tube, and 20 indicates a mixed ion exchange resin transfer tube.

The ion exchange resin that has reached saturation in the demineralization tower (not shown) is introduced into the cation exchange resin regeneration tower 5, which also serves as a backwash separation tower, through a resin introduction pipe 8. Next, the ion exchange resin in the ion exchange resin tank 13 for separation and supplementation is mixed with air introduced through the air introduction pipe 14 and sluicing water introduction pipe 15.
After being mixed with the water introduced from the ion exchange resin transfer pipe 17 for separation and supplementation into the cation exchange resin regeneration tower 5, the water is introduced from the backwash water introduction pipe 6 together with the ion exchange resin from the desalination tower. At the same time, the cation exchange resin layer 1 and the anion exchange resin layer 2 are
and a mixed ion exchange resin layer 3 in which both ion exchange resins are mixed. In this case, the layer 3 shown as the mixed ion exchange resin layer is not in a uniformly mixed state, but in a normal state, it is at the midpoint between the anion exchange resin extraction pipe 10 and the mixed ion exchange resin extraction pipe 11. There is a separation plane of both anion exchange resin and cation exchange resin, and a mixed layer of both ion exchange resin exists above and below this plane, and as the distance from this separation plane increases, the anion exchange resin or The concentration of cation exchange resin decreases,
In the extraction tube 10 or 11, there is a layer only of anion exchange resin or cation exchange resin, respectively. To explain in more detail, the separation surface 3'
is formed relatively clearly, but a layer containing some cation exchange resin is formed above it.
The amount of cation exchange resin mixed in decreases as you go up, and the lower part of the anion exchange resin extraction pipe 10 is designed to have a layer of only anion exchange resin to avoid mixing of cation exchange resin. However, in the drawings, all the resin layers that are not extracted by the anion exchange resin extraction tube 10 but are extracted by the mixed ion exchange resin extraction tube 11 are shown as mixed ion exchange resin layers. Similarly to the above, the upper surface of the mixed ion exchange resin extraction tube 11 is also a layer of only cation exchange resin.

Although the backwash time depends on the amount of water introduced from the backwash water introduction pipe 6, 20 to 30 minutes is sufficient. During backwashing, backwash water (waste water) used for backwashing is discharged from the system through an overflow pipe 18.

Next, the air introduced from the air introduction pipe 7,
The anion exchange resin in the anion exchange resin layer 2 is extracted from the anion exchange resin extraction tube 10 by the water introduced from the sluicing water introduction tube 16, and the anion exchange resin is regenerated by the anion exchange resin transfer tube 19. It is guided to a column 12, where it is regenerated with an aqueous caustic soda solution, and then mixed with a cation exchange resin regenerated in a cation exchange resin regeneration column 5, which will be described later, and sent to a demineralization column.

Next, the mixed ion exchange resin of the mixed ion exchange resin layer is extracted from the mixed ion exchange resin extraction pipe 11 by air introduced from the pipe 7 and water introduced from the sluicing water introduction pipe 16, and the mixed ion exchange resin is extracted from the mixed ion exchange resin extraction pipe 11. The resin is introduced into an ion exchange resin tank 13 for separation and replenishment through a resin transfer pipe 20.

On the other hand, the cation exchange resin remaining at the bottom of the cation exchange resin regeneration tower is regenerated with sulfuric acid in the cation exchange resin regeneration tower, and then mixed with the regenerated anion exchange resin and desalted as described above. sent to the tower.

The amount of ion exchange resin charged to the desalination tower is usually kept constant, and the amounts of anion exchange resin and cation exchange resin are kept constant depending on their respective ion exchange capacities. There must be.

By the way, when transferring resin from a demineralization tower to a cation exchange resin regeneration tower (separation tower) or from an ion exchange resin tank for separation and replenishment to a cation exchange resin regeneration tower, etc., the operating conditions, etc. In some cases, the resin may not be completely transferred. In such a case, the amount of ion exchange resin becomes unbalanced between the demineralization towers, and the amounts of anion exchange resin and cation exchange resin also fluctuate, which is not preferable.

That is, for example, after transferring the ion exchange resin to be regenerated from the demineralization tower to the cation exchange resin regeneration tower 5,
When transferring the ion exchange resin from the ion exchange resin tank 13 for separation and replenishment to the cation exchange resin regeneration tower 5, if the ion exchange resin is not completely transferred, the resin head h in the cation exchange resin regeneration tower ', and if the normal resin head is h, the total amount of resin will decrease by h - h', and therefore, when the recycled resin is returned to the demineralization tower, the amount of resin in the demineralization tower will be h. It is reduced by −h′. On the other hand, in this case, although the amount of cation resin that is regenerated and returned to the demineralization tower is always constant at the designed amount (because the height of the mixed ion exchange resin extraction pipe is constant), the amount of resin is When the amount of anion exchange resin decreases, the amount of anion exchange resin to be regenerated decreases (in the above case, the amount of anion exchange resin decreases by h−h′), and both the anion and cation exchange resins are When the desalination tower is returned to the regenerated desalination tower, the total amount of resin in the demineralization tower decreases as described above, and the amount of anion exchange resin and the amount of cation exchange resin become different from the predetermined values. Not good for driving.

In addition, in the previous ion exchange resin regeneration cycle, if the entire amount of ion exchange resin in the ion exchange resin tank 13 for separation and replenishment was not completely transferred, the mixed ion exchange resin is transferred from the mixed ion exchange resin extraction pipe 11 through the transfer pipe 20 to the ion exchange resin for separation and replenishment. Since the amount of resin returned to the ion exchange resin tank 13 is always constant, in this case, the amount of resin stored in the ion exchange resin tank 13 for separation and replenishment for the next regeneration cycle is greater than the predetermined amount. When the entire amount of ion exchange resin in the separation/replenishment ion exchange resin tank 13 is transferred to the cation exchange resin regeneration tower 5 in the regeneration cycle, the amount of resin in the tower 5 will be greater than the predetermined amount. In other words, the ion exchange resin head in this case is
h'' means that the amount of anion exchange resin introduced into the anion exchange resin regeneration tower is greater than the predetermined amount by h'' - h, and both ion exchange resins are regenerated and returned to the demineralization tower. In this case, the total amount of resin increases by h''-h, and the amount of anion exchange resin also increases by this amount.

If an imbalance occurs in the amount of ion exchange resin in the desalting tower or the amount of anion and cation exchange resins due to such reasons, two resin extraction pipes are used to remove both anion and cation. With the method of separating ion exchange resins, it is not only impossible to naturally correct these imbalances, but also it is not possible to effectively prevent such imbalances.

The decrease in the amount of resin may also be caused by the fact that the resin is crushed during the outside operation due to transfer as described above and is discharged by backwashing.

[Purpose of the invention]

The present invention solves the above-mentioned problems of the prior art, and by constantly separating and regenerating a constant amount of pure anion exchange resin and cation exchange resin and returning them to the desalination tower, An object of the present invention is to provide a method for keeping the amount of ion exchange resin and the respective amounts of anion exchange resin and cation exchange resin constant.

[Structure of the invention]

The present invention is a method for separating a used anion exchange resin and a cation exchange resin into their respective resins in order to regenerate the mixture. After mixing the ion exchange resin for separation and supplementation into the mixture of anion exchange resin and cation exchange resin to be regenerated, backwashing is performed, and the anion exchange resin layer, mixed ion exchange resin layer, and cation exchange resin layer are After three layers are formed, the surplus anion exchange resin is first extracted from the surplus anion exchange resin extraction pipe installed horizontally at the top of the separation column into an ion exchange resin tank for separation and replenishment, and then the surplus anion exchange resin is removed. A certain amount of anion exchange resin is extracted to an anion exchange resin regeneration tower by an anion exchange resin extraction pipe installed horizontally at a predetermined interval below the extraction pipe. This is a method for separating an ion exchange resin to be regenerated, which is characterized by extracting a mixed ion exchange resin layer into an ion exchange resin tank for separation and replenishment using a horizontally provided mixed ion exchange resin extraction pipe.

The present inventors conducted various studies to improve the above-mentioned drawbacks of the conventional method, and as a result, the inventors of the present invention sandwiched the mixed ion exchange resin layer formed in the cation exchange resin regeneration tower (separation tower), A cation exchange resin regeneration tower (separation tower) has two ion exchange resin extraction pipes, an anion exchange resin extraction pipe and a mixed ion exchange resin extraction pipe, in a pure anion exchange resin layer and a cation exchange resin layer. ), in which
A desalination tower (ion exchange tower) is installed above the anion exchange resin extraction pipe and from the ion exchange resin extraction pipe.
By providing a surplus anion exchange resin extraction pipe at a position where an amount of anion exchange resin commensurate with the amount of anion exchange resin to be charged can be extracted, and by using a large amount of ion exchange resin for separation and supplementation. Is there an imbalance in the amount of resin between the demineralization towers and the amount of both ion exchange resins, or is there an imbalance in the amount of resin between the demineralization towers due to incomplete resin transfer from the regeneration tower, etc.? It has been found that even when imbalances occur in the amounts of both ion exchange resins, these imbalances can be corrected naturally (automatically).

Next, an embodiment of the present invention will be described based on FIG. 2.

〔Example〕

In FIG. 2, symbols 1 to 20 are replaced by symbols 4 and 9.
and have the same meaning as the symbols in Figure 1 except for 21,
Reference numeral 4 indicates a surplus anion exchange resin layer, 9 a surplus anion exchange resin extraction pipe, and 21 a surplus anion exchange resin transfer pipe.

The present invention will be explained in detail based on FIG.

The ion exchange resin that has reached saturation in the demineralization tower (not shown) is introduced into the cation exchange resin regeneration tower 5, which also serves as a backwash separation tower, through the resin introduction pipe 8, and then the ion exchange resin for separation and supplementation is introduced into the cation exchange resin regeneration tower 5, which also serves as a backwash separation tower. tank 1
The ion exchange resin in 3 is introduced into the cation exchange resin regeneration tower 5 through the separation/replenishment ion exchange resin transfer pipe 17 using air introduced from the air introduction pipe 14 and water introduced from the sluicing water introduction pipe 15. , mixed with the saturated ion exchange resin from the demineralization tower, which was previously introduced into the tower. At this time, be sure to mix enough ion exchange resin for separation and compensation to form a surplus anion exchange resin layer, and add enough ion exchange resin for separation and compensation to form a mixed ion exchange resin layer. Allow to mix.

Next, backwashing is performed with backwash water introduced from the backwash water introduction pipe 6, and the cation exchange resin layer 1 and the anion exchange resin layer 2 are washed using the difference in specific gravity between the cation exchange resin and the anion exchange resin. Then, a mixed ion exchange resin layer 3 and a surplus anion exchange resin layer 4 are formed. Backwashing only needs to be carried out for about 20 to 30 minutes, during which time the backwashing waste liquid is discharged out of the system through the overflow pipe 18.

Next, the surplus anion exchange resin is extracted from the surplus anion exchange resin extraction pipe 9 using air introduced from the air introduction pipe 7 and water introduced from the sluicing water introduction pipe 16. It is transferred via the transfer pipe 21 to the ion exchange resin tank 13 for separation and replenishment.

Next, the anion exchange resin in the anion exchange resin layer 2 is extracted from the anion exchange resin extraction tube 10 by the air introduced from the air introduction tube 7 and the water introduced from the sluicing water introduction tube 16. The anion exchange resin is led to the anion exchange resin regeneration tower 12 by the anion exchange resin transfer pipe 19, where it is regenerated with a caustic soda aqueous solution, and then mixed with the cation exchange resin regenerated in the cation exchange resin regeneration tower described later. and sent to the desalination tower.

The mixed ion exchange resin of the mixed ion exchange resin layer is extracted from the mixed ion exchange resin extraction pipe 11 by air introduced from the air introduction pipe 7 and water introduced from the sluicing water introduction pipe 16, and mixed ion exchange is performed. The resin is introduced into the ion exchange resin tank 13 for separation and replenishment through the resin transfer pipe 20, and used for the next separation of ion exchange resin.

On the other hand, the cation exchange resin remaining at the bottom of the cation exchange resin regeneration tower 5 is regenerated with sulfuric acid in the tower, and then mixed with the regenerated anion exchange resin and sent to the demineralization tower. Sent.

In the present invention, the amount of cation exchange resin in cation exchange resin layer 1 and the amount of cation exchange resin in anion exchange resin layer 2
The height of the mixed ion exchange resin and the spacing between the surplus anion exchange resin extraction pipe 10 and the ion exchange resin extraction pipe 9 are adjusted so that the amount of ion exchange resin inside is equal to the amount of resin used in each demineralization tower. Therefore, a certain amount of anion exchange resin and cation exchange resin is always regenerated and returned to the desalting tower, and there is no imbalance in the amount of ion exchange resin between the desalting towers. There is no possibility that the amounts of both ion exchange resins in the desalting tower become unbalanced. Furthermore, even if the imbalance occurs for some reason, this imbalance will be naturally corrected during repeated regenerations, and stable operation can therefore be achieved.

Further, it is natural that the anion exchange resin extraction pipe 10 is provided at a height that prevents the cation exchange resin from being mixed into the anion exchange resin layer.

〔Effect of the invention〕

According to the present invention, by using three extraction tubes: a surplus anion exchange resin extraction tube, an anion exchange resin extraction tube, and a mixed ion exchange resin extraction tube, a certain amount of pure cation exchange resin and a certain amount of cation exchange resin can be extracted. It can be separated into pure anion exchange resin and regenerated.
Therefore, not only can a constant amount of each ion exchange resin be secured without reverse regeneration, but it can also be used in the event of an imbalance in the amount of resin between the desalting towers or an imbalance of both anion and cation exchange resins in the desalting tower. Also,
By repeating playback, these imbalances can be eliminated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining a conventional method for separating ion exchange resins, and FIG. 2 is a schematic diagram for explaining a method for separating ion exchange resins according to the present invention. 1... Cation exchange resin layer, 2... Anion exchange resin layer, 3... Mixed ion exchange resin layer, 4...
Excess anion exchange resin layer, 5... Cation exchange resin regeneration tower, 6... Backwash water introduction pipe, 8... Ion exchange resin introduction pipe, 9... Excess anion exchange resin extraction pipe, 10... Anion Ion exchange resin extraction tube, 11
... mixed ion exchange resin extraction pipe, 12 ... anion exchange resin regeneration tower, 13 ... ion exchange resin tank for separation and replenishment.

Claims (1)

[Claims] 1 In a method of separating the used anion exchange resin and cation exchange resin into their respective resins in order to regenerate the mixture, the resin to be regenerated is introduced from the demineralization tower into the separation tower (cation exchange resin tower). After mixing the ion exchange resin for separation and supplementation into the mixture of anion exchange resin and cation exchange resin, backwashing is performed and the three layers of an anion exchange resin layer, a mixed ion exchange resin layer, and a cation exchange resin layer are separated. After the formation, the surplus anion exchange resin is first extracted from the surplus anion exchange resin extraction pipe installed horizontally at the upper part of the separation column into an ion exchange resin tank for separation and replenishment.
Next, a certain amount of anion exchange resin is extracted to an anion exchange resin regeneration tower by an anion exchange resin extraction pipe installed horizontally at a predetermined interval below the surplus anion exchange resin extraction pipe, and then anion exchange resin is extracted. A method for separating an ion exchange resin to be regenerated, characterized in that a mixed ion exchange resin layer is extracted into an ion exchange resin tank for separation and replenishment by a mixed ion exchange resin extraction pipe provided horizontally below the resin extraction pipe.