JPS582431Y2 - Ion exchange tower used for upstream regeneration - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an ion exchange column used for upflow regeneration.

Traditionally, both downflow water, downflow regeneration (hereinafter referred to as downflow regeneration) and downflow flow water, upflow regeneration (hereinafter referred to as upflow regeneration) are the most common operations for ion exchange equipment. Comparing these two methods, when regenerating using the same regenerating agent, upflow regeneration generally allows for higher purity treated water than downflow regeneration.

In other words, the amount of regenerant required to obtain treated water of a predetermined purity is smaller in upflow regeneration than in downflow regeneration.

Upflow regeneration has been increasingly adopted in recent years because of its benefits compared to downflow regeneration.

In upward flow regeneration, the regenerant flows upward from the bottom of the column, so a means is required to prevent the ion exchange resin layer from being pushed up and fluidized by the upward flow of the regenerant. A tower is proposed.

For example, in an ion exchange tower that has a space for backwashing in the upper part of the first ion exchange tower, a collector for discharging recycled waste liquid is buried slightly below the top surface of the ion exchange resin layer, and the regenerating agent is transferred to the tower. When flowing upward from the bottom, water or air is introduced from the top of the column and discharged from the recycled waste liquid discharge collector along with the recycled waste liquid, and the resin layer is held by the inflow pressure of the water or air. There is an ion exchange tower for regeneration.

Further, as a second ion exchange tower, there is an ion exchange tower in which the space inside the tower is filled with ion exchange resin without any gaps and regenerated by upward flow.

However, the first ion exchange tower requires the installation of a collector for discharging recycled waste liquid, and the number of valves increases, which increases construction costs.In addition, the ion exchange resin present in the upper part of the collector Since there is no contact with the regenerating agent during regeneration, there is a drawback that the ion exchange resin in this part becomes ineffective in terms of ion exchange.

In addition, in the second ion exchange tower, the ion exchange resin is filled without any gaps in the space inside the tower, so the ion exchange resin cannot be backwashed, so a separate backwash hopper must be installed, which also increases construction costs. There are drawbacks.

Furthermore, both have drawbacks as explained below.

In other words, in the currently used upflow regeneration ion exchange towers, after finishing passing water in a downward flow, the regenerant is passed through it in an upward flow without backwashing the entire ion exchange resin layer. However, since there is generally a certain amount of suspended solids in the water to be treated, it is impossible to completely omit backwashing, and backwashing is carried out once every few cycles to once every ten cycles. It is necessary to perform backwashing.

The regeneration efficiency of a cycle with backwashing is considerably lower than that of a cycle without backwashing, so a large amount of regenerant must be used in a cycle with backwashing, which requires the use of chemicals. This method has the drawbacks of increased costs, and furthermore, automatic operation requires complicated operation, which also increases construction costs.

This invention solves these shortcomings all at once, and in an ion exchange tower in which the regenerant is introduced from the bottom of the ion exchange tower to regenerate the ion exchange resin in an upward flow, approximately 70%
Used for upward flow regeneration, characterized in that the ion exchange resin below the ion exchange resin is hardened with an adhesive to prevent the ion exchange resin from flowing due to the upward flow of liquid during the backwashing process, regeneration process, etc. It relates to ion exchange towers.

The present invention will be explained below using the drawings.

FIG. 1 is an explanatory diagram showing the configuration of a cation column of a pure water production apparatus which is an example of an embodiment of the present invention.
A cation exchange resin 2 hardened with an adhesive is filled inside, and a cation exchange resin 2' that is not hardened with an adhesive is filled above it.

In normal cases, strongly acidic cation exchange resins are used for both cation exchange resins 2 and 2'.

A discharge pipe 3 is attached to the lower part of the ion exchange tower 1, and a regenerant inflow pipe 4, a backwash water flow pipe 5, and a treated water outflow pipe 6 are connected to the discharge pipe 3.

Further, a distributor 7 is attached to the upper part of the ion exchange column 1, and a treated water flow pipe 8 is connected to the waste repeater 7, and a backwash water outflow pipe 9 is connected to the treated water inflow pipe 8.

Note that 10 is a supporting bed for the ion exchange resin, and a silica stone or the like is used for the passage.

When treating water in this ion exchange tower, the water to be treated flows in from the water inflow pipe 8, flows downward through the ion exchange resins 2' and 2, and the treated water flows through the water outflow pipe 6. Let it flow.

Industrial water is generally used as the water to be treated, and it is normal for the water to be treated to contain ions such as calcium ions, magnesium ions, and sodium ions as well as some suspended solids. When water is passed through the cation exchange resins 2' and 2 in a downward flow, the arrangement of the ion forms of the cation exchange resin at the end point of the water flow is as shown in Figure 2, from the upper layer to the lower layer, in the form of calcium and magnesium. The order is A (hereinafter referred to as calcium form), sodium form B, and hydrogen form C, and turbidity mainly accumulates in the calcium form A cation exchange resin.

Note that 2' indicated by a dotted line in FIG. 2 indicates a cation exchange resin that is not separated with an adhesive, and 2 indicates a cation exchange resin that is hardened with an adhesive.

Therefore, turbidity also accumulates in the cation exchange resin 2' that is not hardened with adhesive.

As mentioned above, in the ion exchange towers currently in use for upflow regeneration, regeneration efficiency is improved by performing upflow regeneration in this state without performing backwashing after the downflow water flow has finished. It's increasing.

In other words, when an aqueous solution of hydrochloric acid is flowed upward as a regenerating agent into a cation exchange resin layer in which hydrogen form C, sodium form B, and calcium form A are arranged from the lower layer to the upper layer, the hydrochloric acid becomes hydrogen. First, the sodium cation exchange resin is desorbed and converted into hydrogen form, and the waste sodium chloride further desorbs the calcium cation exchange resin in the upper layer, converting it into sodium form. In addition, hydrochloric acid comes into contact with the sodium-type cation exchange resin and converts it into hydrogen form. Desorption occurs in sequence, and the calcium-type cation exchange resin, which is originally difficult to desorb with hydrogen ions, is desorbed. By interposing sodium ions, which are better at desorption than hydrogen ions, desorption is effected effectively, and the cation exchange resin in the hydrogen form present at the end of water flow can be retained at the bottom of the ion exchange resin layer. This makes it ideal for regeneration operations, and the hydrogen-type cation exchange resin produced by regeneration can be made larger.

However, as shown in Figure 2, by repeating water flow and regeneration, a large amount of turbidity accumulates on the top of the ion exchange resin layer, increasing pressure loss, so it is necessary to remove this turbidity. Backwashing must be carried out from time to time.

In conventional upflow regeneration ion exchange towers, when backwashing is performed, the cation exchange resin is mixed and the arrangement of each ion type is disturbed, so in the regeneration immediately after backwashing, the ideal The regeneration effect could no longer be obtained, and therefore a large amount of regenerant had to be used.

In the ion exchange tower of the present invention, the ion exchange resin at the bottom is hardened with an adhesive, so even if backwashing is performed, the arrangement of ion types in this part will not be disturbed.

That is, in performing backwashing in the ion exchange tower of the present invention, backwash water flows upward from the backwash water flow pipe 5, and backwash wastewater is discharged from the backwash water outflow pipe 9.
As shown in the figure, the cation exchange resin 2 in the lower layer is adhesive and is kept in its original state without flowing.
The cation exchange resins of each ionic form, hydrogen form C, sodium form B, and some calcium form A, do not mix.

On the other hand, the cation exchange resin 2', which is mostly calcium type A that has not been hardened with adhesive, expands due to the upward flow, and the turbidity is discharged to the outside of the column.

In this way, in the ion exchange tower of the present invention, only the ion exchange resin that is not hardened with adhesive flows during backwashing, so the arrangement of the ion exchange resin of each ion type is not disturbed at the end of water flow, and the reverse Even if washing is performed, the ideal regeneration effect as described above will not be inhibited.

In order to regenerate this ion exchange tower, after settling the ion exchange resin, an aqueous solution of, for example, hydrochloric acid as a regenerant is passed through the regenerant inlet pipe 4 in an upward flow at a low flow rate, and the regenerated waste liquid is backwashed. The water is discharged from the water outlet pipe 9.

It goes without saying that the cation exchange resin 2 does not flow at all during the main regeneration, but the cation exchange resin 2'
will be somewhat fluid.

However, in upflow regeneration, the most important part of the regeneration is the ion exchange resin layer in the lower layer, so even if the ion exchange resin in the upper layer flows a little, it does not affect the regeneration effect that much.

A collector is installed in the upper part of the ion exchange resin 2', and during regeneration, air is introduced from the upper part of the ion exchange tower, and the recycled waste liquid and air are discharged from the collector to generate the cation exchange resin 2'. It is okay to play the data while retaining it.

Next, the adhesive used in the present invention will be explained.

As an adhesive, ion exchange resin is strongly bonded, and
It is desirable that the adhesive is resistant to chemicals such as acids and alkalis, and that the solidified adhesive itself has good dispersibility with respect to liquids.

Adhesives with these properties usually include epoxy,
There are acrylic adhesives, phenolic adhesives, vinyl chloride adhesives, polyvinyl alcohol adhesives, etc., and it is best to select an appropriate adhesive from these adhesives.

In general, the volume of ion exchange resins changes depending on the ionic form; for example, when a strongly acidic cation exchange resin changes from a sodium form to a hydrogen form, its volume swells.
Conversely, when changing from hydrogen form to sodium form, its volume contracts.

・For strongly basic anion exchange resins, their volume swells when they change from a chlorine form to a hydroxyl form, and conversely, their volume contracts when they change from a hydroxyl form to a chlorine form.

Therefore, as the ion exchange resin is repeatedly regenerated and water is passed through, the ion exchange resin repeatedly swells and contracts, which may cause cracks to form in the ion exchange resin sealed with adhesive.

In order to prevent such a phenomenon, it is preferable to mix some particulate matter with the ion exchange resin and seal it with an adhesive.

The granules used are inorganic or organic granules that are stable against chemicals such as acids and alkalis.The inorganic material is granular material such as silica stone and anthracite, and the organic material is a copolymer of divinylbenzene and styrene. , divinylbenzene and acrylic or methacrylic copolymer,
Granules made of polyethylene, vinyl chloride, various synthetic rubbers, etc. are used.

By mixing these particulates with the ion exchange resin, the particulates act as a buffer against the swelling and contraction of the ion exchange resin, making it possible to prevent cracks from forming in the hardened ion exchange resin. .

Therefore, it is preferable that the granules used have some degree of elasticity.

Next, the amount of ion exchange resin to be hardened will be explained.

In the present invention, approximately 70% of the lower ion exchange resin is hardened with an adhesive, but this amount may be determined depending on the composition of the water to be treated.

For example, in a cation exchange tower, as shown in FIG. 2, it is preferable to solidify the ion exchange resin in the lower part of the column other than the cation exchange resin remaining as calcium form A at the end of the water flow.

Therefore, in treated water with a low sodium percentage, the amount of ion exchange resin to be solidified tends to be small, and in treated water with a high sodium percentage, the amount of ion exchange resin to be solidified tends to increase.

In the anion exchange tower as well, the amount of ion exchange resin to be solidified is changed depending on the silica percentage of the water to be treated, and it is preferable to leave the chlorine type or sulfuric acid type part in the upper layer without solidifying it as much as possible.

However, if too much ion exchange resin is hardened, the amount of ion exchange resin that can be backwashed will decrease, and the turbidity shown in FIG. 2 will reach the hardened ion exchange resin layer.

When the suspended matter reaches the solidified ion exchange resin layer, it becomes difficult to discharge it by backwashing, so the amount of solidified ion exchange resin needs to be at most 70% or less.

As the ion exchange resin used in the present invention to solidify, as mentioned above, the ion exchange resin undergoes volume change during water passage and regeneration, so it is generally preferable to use a highly crosslinked ion exchange resin that exhibits little volume change.

The ion exchange tower of the present invention can be applied to either a cation tower filled with a cation exchange resin or an anion tower filled with an anion exchange resin, but it is also possible to apply a strong electrolyte ion exchange column with a weak electrolyte ion exchange resin in the upper layer. It can also be applied to a two-bed ion exchange tower with a resin as the lower layer.

For example, by creating an ion exchange column in which the strong electrolyte ion exchange resin in the lower layer of a two-layer bed is hardened with an adhesive and the weak electrolyte ion exchange resin in the upper layer is not hardened with adhesive, the weak electrolyte ion exchange resin can be used even in a fluid state. Using the property of being able to be regenerated, it is possible to perform backwashing while regenerating the weak electrolyte ion exchange resin, making it possible to completely omit the backwashing process and further reducing chemical costs. I can do it.

As explained above, in the ion exchange tower according to the present invention, the arrangement of each ion type is not disturbed even when backwashing is performed, and therefore, even if backwashing is performed every time, the ion exchange tower of the conventional upflow regeneration is not affected. It is possible to achieve regeneration efficiency similar to that of a backwash cycle, which reduces chemical costs.Furthermore, construction costs are reduced because there is no longer a need for a holding device for the ion exchange resin layer during regeneration, which was previously required. It has various advantages, such as the fact that it is possible to perform backwashing every cycle and discharge suspended solids, so there is no need for highly sophisticated pretreatment of the water to be treated.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are all drawings showing an embodiment of the present invention, and FIG. 1 is an explanatory diagram showing the configuration of a cation column of a pure water production apparatus that is an example of an embodiment of the present invention. Figure 2 is an explanatory diagram showing the arrangement of ionic forms of the ion exchange resin at the end point of water flow through the cation tower, and Figure 3 is an explanatory diagram showing the state of the cation tower during backwashing. be. 1... Ion exchange tower, 2... Cation exchange resin, 3... Discharge pipe, 4... Regenerant inflow pipe, 5...・Backwash water inflow pipe, 6...
- Treated water outflow pipe, 7...dis) I) Computer, 8... Treated water inflow pipe, 9... Backwash water outflow pipe, 10...・Support floor, A...
Calcium form, B... Sodium form, C...
...Hydrogen form, D...suspended matter.

Claims (2)

[Scope of utility model registration request] (1) In an ion exchange tower in which a regenerating agent is introduced from the lower part of the ion exchange tower to regenerate the ion exchange resin in an upward flow,
An upward flow characterized in that the lower ion exchange resin within about 70% is hardened with an adhesive to prevent the ion exchange resin from flowing due to the upward flow of liquid during backwashing, regeneration, etc. Ion exchange tower used for regeneration. (2) The increase as described in Paragraph 1 of the Utility Model Registration Claim in which approximately 70% or less of the lower ion exchange resin is mixed with inorganic or organic granules that are stable to chemicals such as acids and alkalis and solidified with a welding agent. Ion exchange tower used for stream regeneration.