JPS631898B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to ion exchange resins involved in ion exchange operations used in pure water production, condensate desalination, and other liquid treatments that require precise purification of liquids. This relates to a method of transporting.

[Conventional technology]

Conventionally, hydrogen type (H type) strongly acidic cation exchange resin (hereinafter referred to as ``CR'') and hydroxyl type (OH type) strongly basic anion exchange resin (hereinafter referred to as ``AR'') were mixed and filled. Mixed bed ion exchange towers are widely used in the fields of pure water production and condensate desalination. There are two methods for regenerating the spent resin in this mixed bed type ion exchange tower: external regeneration and in-column regeneration, and the external regeneration method is generally used in condensate desalination equipment. The normal regeneration procedure in the case of the external regeneration method is as follows: First, the resin in the mixed bed ion exchange tower (hereinafter referred to as the desalination tower) is transferred to the regeneration tower (first regeneration tower).
A reverse flow is performed in the first regeneration tower to form an AR layer in the upper layer and a CR layer in the lower layer. CR and AR have different specific gravity to water, so backwashing creates this stratification. Later, the upper layer AR
is further transferred to another regeneration tower (second regeneration tower), and CR remains in the first regeneration tower. In the first regeneration tower, an acid such as hydrochloric acid or sulfuric acid is passed to regenerate CR, and in the second regeneration tower, an alkali such as caustic soda is passed to regenerate AR. After passing the acid and alkali, both resins are washed, and after washing, both resins are transferred to a tower called a resin mixing tower, where CR and AR are mixed using air. In this way, the resin in the desalting tower is regenerated. There are some modified methods, such as a method that does not have a resin mixing tower and mixes CR and AR in the demineralization tower, and a method that does not have a second regeneration tower and passes acid and alkali through the first regeneration tower. There is.

In recent years, with the demand for high quality treated water, the degree of separation of CR and AR in the above-mentioned regeneration procedure has also become an issue. In other words, after backwashing and separation in the first regeneration tower, the upper layer
Whenever you transfer AR to the second regeneration tower, CR and
Since the ARs are in contact with each other, it is impossible to completely separate the two using normal means. Therefore, it is inevitable that some CR gets mixed into the second regeneration tower for AR regeneration, or that some AR remains in the first regeneration tower for CR regeneration. When CR enters the second regeneration tower, it comes into contact with, for example, caustic soda, and becomes Na form. When AR remains in the first regeneration tower, it comes into contact with sulfuric acid and hydrochloric acid, and AR is
It becomes HSO ₄ type and CI type. In the past, the generation of small amounts of impurity ion forms (other than H type and OH type) did not pose much of a problem, but recently, in pure water production that requires high quality treated water, CR of impurity ion form Since the presence of and AR causes impurity ion leakage, there is a tendency to suppress their generation as much as possible.

In order to suppress the formation of such impurity ion-type resins, it is necessary to separate CR and AR more strictly, and for this reason, as a known method, a mixed resin of CR and AR is used in a regeneration tower. During backwash separation, backwash separation is performed after adding CR and AR prepared separately, and the CR and AR are regenerated with acid and alkali, respectively, with the resin near the separation interface removed in an amount commensurate with the amount added. There is a method in which the resin near the separation interface is stored separately and used as a resin to be added before backwash separation during the next regeneration.

[Problem that the invention seeks to solve]

To carry out this conventional method, after backwashing and separating to form two layers, the upper layer AR and the lower layer CR, there is a step (a) in which AR is pulled out from above the separation interface. It is also necessary to perform two steps (b) to pull out the AR and CR from below. That is, the resin layer after backwashing and separation is divided into three parts: an upper part consisting only of AR, an intermediate part containing the separation interface of AR and CR and containing both resins, and a lower part consisting only of CR. In this case, process (a) and process (b) have the same effect no matter which one is done first. If step (a) is done first, the top, middle, and bottom parts are pulled out one by one, but if step (b) is done first, the top and middle parts are pulled out all at once. It is then pulled out and transferred to another regeneration tower, backwashed again in the other regeneration tower, and then only the upper part is pulled out. Both have their advantages and disadvantages, and it cannot be said that one is better than the other (see Figure 1).

The present invention relates to the case of executing step (b) of these two steps, that is, the step of pulling out AR and CR from below the separation interface, and this step (b)
The middle part (or upper and middle part) resin drawing methods used in Conventionally, a method has been used in which a transfer water outlet and a draw-out port are provided at the draw-out position and the transfer water is blown out while being drawn out. Operational instability remains. On the other hand, the latter method does not have such instability, but the AR included in the middle or upper part
is often deposited on the lower resin and remains without being pulled out. Contamination of the lower resin with AR goes against the original purpose and must be avoided. The amount of AR deposited and remaining on the lower resin naturally depends on the positional relationship between the extraction port and the separation interface, but even if the extraction port is set far below the separation interface, a small amount of AR will still remain. is unavoidable. This is because in the latter method, the extraction port and the transfer water outlet are at the same height, so the flow state of the resin at the level of the extraction port is poor, and it is difficult for the AR that is located away from the extraction port to completely flow out. By not doing it.

The present invention solves these conventional drawbacks,
The amount of resin extracted (the amount that remains when turned over) is constant and does not fluctuate, and the upper layer AR does not remain on the lower resin, which should consist only of CR, making the recycling process more efficient. In particular, we aimed to provide a useful method that compensates for the shortcomings of the conventional method by performing the drawing of the middle part (or the middle part and the upper part) resin in two stages and almost eliminating the residual AR on the upper surface of the lower part resin. It is something.

[Means for solving problems]

The present invention provides a mixed bed type ion exchange tower equipped with an ion exchange resin that can be separated into upper and lower layers by backwashing, and a transfer water jet set in the upper part of the lower ion exchange resin layer separated by backwashing. Transfer water is spouted from the jetting section, and a resin main draw-out port is provided near the jetting section, and a resin sub-pulling port is provided near the ion exchange resin layer above the spouting section or the interface between the upper and lower two layers. When drawing out the resin using the auxiliary drawing port, the resin above the sub-drawing port is first pulled out, and then the resin above the main drawing port is pulled out from the normal drawing port.

[Effect]

In this method, AR and CR are connected from below the separation interface.
A water pipe for blowing out the transferred water is provided at almost the same height as the drawing port (hereinafter referred to as the normal drawing port) from which the water is drawn out, and the water pipe is used as the transferred water spouting part, and above the water pipe and the normal drawing port, the above-mentioned separation pipe is provided. A sub-drawing port is provided at a height below the interface or near the separation interface, and the transferred water is first blown out from the water pipe to backwash the resin to be pulled out, then the sub-drawing port is opened to draw out the resin, and the sub-drawing port is opened to draw out the resin. After the resin above the drawing port has almost completely flowed out, the sub drawing port is closed and the resin above the main drawing port is pulled out from the main drawing port.

In this case, when the resin is being pulled out from the sub-drawing port, the height from the water pipe to the sub-drawing port is in a backwash state, and the level where the sub-drawing port is installed is in a fluid state and the resin is in a fluid state. Because the movement is smooth, almost no resin remains above the sub-extraction port. In addition, after the resin above the sub-drawing port has almost completely flowed out, the sub-drawing port is closed and the resin is pulled out from the normal drawing port, so even if the flow condition at the level of the normal drawing port is poor, the resin at the bottom will still flow out. What remains on the top surface is the resin between the water pipe and the sub-outlet, that is, CR, and no AR remains. The distance between the auxiliary outlet and the water pipe (or the main outlet) is sufficient as long as the level of the auxiliary outlet is in a sufficiently fluid state, and usually it is 50 mm or more. Also, the sub-extraction port must be below the separation interface between CR and AR. The positional relationship between the forward outlet and the water pipe varies slightly depending on the shape of the forward outlet and the shape of the water pipe, so it cannot be strictly specified, but it is important to note that the positional relationship between the forward outlet and the water pipe is very close to each other. Consider this so that there is no difference. As a general rule, it is best to have the normal outlet and the water pipes at or near the same level.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIG. 2. The ion exchange resin tower 1 is provided with water collection and distribution pipes 2 and 3 at the upper and lower parts thereof, and the intermediate part thereof is for discharging water for transferring the resin. A water pipe 4 (hereinafter simply referred to as water pipe) is installed inside and has an ion exchange resin separated into upper and lower two layers, that is, an AR layer 9 and a CR layer 10. The water pipe 4 is located above the lower CR layer near the separation interface, and has a normal drawing port 6 for resin drawing at the same level and a secondary drawing port 5 at a predetermined level interval above it in the tower body. In addition, a bottom extraction port 7 is provided at the bottom and a supply/exhaust port 8 is provided at the top of the tower so that they can be opened and closed.

When the resin above the height of the normal extraction port 6 is to be pulled out, the transferred water is first blown out from the water pipe 4 and discharged from the top water collection and distribution pipe 2.
Backwash the upper part of the water pipe 4. Next, the sub-drawing port 5 is opened to begin drawing out the resin. At this time, drainage from the top water collection and distribution pipe 2 is stopped, but it is preferable to introduce pressurized fluid, such as pressurized air, from the supply/exhaust port 8 at an appropriate time. While maintaining the height between the water pipe 4 and the sub-outlet 5 in a backwashed state, the sub-outlet 5 is opened.
When the resin is pulled out from the auxiliary drawing port 5 and almost no resin is discharged from the sub-drawing port 5, the main drawing port 6 is opened and the sub-drawing port 5 is closed. Through such a procedure, the resin in the upper layer is pulled out through the normal pull-out port 6.

The above procedure shows a typical procedure for carrying out the present invention, and the procedure for carrying out the present invention is not limited to the above procedure.

If the resin is extracted in this way, almost no AR will remain in the ion exchange resin column 1.

When drawing out the resin, if necessary, after the discharge of the upper layer is completed, backwash water is introduced from the bottom water collection and distribution pipe 3 and discharged from the top water collection and distribution pipe 2 to backwash the lower layer, and the bottom extraction port 7 is opened. The lower part may be pulled out by using the water supply pipe 2. When the drawing starts, the water distribution from the top water collection and distribution pipe 2 is stopped, and pressurized air is introduced from the supply/exhaust port 8. In this way, the upper layer portion and the lower layer portion can be pulled out separately, and the portion of the upper layer portion above the sub-drawing port 5 does not mix into the lower layer portion.

In the specific example shown in Fig. 3, the column (inner diameter 470 mm) 11 of the tower body has a bottom water collection and distribution pipe 12 and a water distribution pipe 13.
The column 11 is equipped with a sub-drawing port 14, a normal drawing port 15, and a bottom drawing port 16.
Fill the shape to a height of 50 mm above the sub-extraction port.
7, followed by strongly basic anion exchange resin 18
(Dowex SBR-P-C) OH type was filled to a bed height of 300 mm. The height of the water pipe 13 and the main draw-out port 15 from the column bottom is 750 mm, and the height of the sub-draw port 14 from the column bottom is 850 mm.

First, water was introduced from the bottom water collection and distribution pipe 12 to backwash the entire layer and settle, and then water was introduced from the water distribution pipe 13 to backwash only the resin above the water distribution pipe 13.
When the upper resin was sufficiently developed and almost no resin flowed out from the sub-drawing port 14, the sub-drawing port was closed and the normal drawing port 15 was opened to allow the resin above the normal drawing port to flow out. After the spill, the remaining resin underneath was backwashed, but no SBR-P-C residue was observed.

Comparative Example Using the apparatus shown in FIG. 3, the same resin filling as in the example was carried out. First, the entire thickness is backwashed, and after settling, water is introduced from the water pipe 13 to backwash only the resin above the water pipe, and when the resin on the top is fully developed, the forward withdrawal port 15 is opened. , the resin above the normal withdrawal port was flowed out. When the lower resin remaining after the spill was backwashed, SBR-P-C remained on the surface layer to a thickness of about 4 mm.

〔Effect of the invention〕

The present invention provides a mixed bed type ion exchange tower equipped with an ion exchange resin that can be separated into upper and lower layers by backwashing, and a transfer water jet set in the upper part of the lower ion exchange resin layer separated by backwashing. Transfer water is spouted from the jetting section, and a resin main withdrawal port provided near the jetting section and a resin secondary withdrawal port provided near the ion exchange resin layer or the interface between the upper and lower two layers above the spouting section are connected. When pulling out the resin using the auxiliary drawing port, the resin above it is pulled out from the sub-drawing port, and then the resin above it is pulled out from the normal drawing port. The extraction is performed in two stages, and there is almost no residual strongly basic anion exchange resin on the upper surface of the cation exchange resin at the bottom, and the resin extraction level is constant and does not fluctuate, making it possible to perform stable and efficient processing using the conventional method. There are benefits that can compensate for the shortcomings.

[Brief explanation of the drawing]

FIG. 1 is a conventional flow sheet, FIG. 2 is a flow sheet of an embodiment of the method of the present invention, and FIG. 3 is a flow sheet of another embodiment. DESCRIPTION OF SYMBOLS 1...Ion exchange resin tower, 2...Top water collection and distribution pipe, 3...Bottom water collection and distribution pipe, 4...Water pipe for discharging transferred water, 5...Sub-drawing port, 6...Forward drawing port, 7
... Bottom extraction port, 8 ... Supply and exhaust port, 9 ... Strong basic anion exchange resin layer, 10 ... Strong acid cation exchange resin layer, 11 ... Column, 12 ... Bottom water collection and distribution pipe, 13 ... Distribution Water pipe, 14...auxiliary extraction port,
15...Front pull-out port, 16...Bottom pull-out port, 1
7... Strongly acidic cation exchange resin layer, 18... Strongly basic anion exchange resin layer.

Claims (1)

[Scope of Claims] 1. In a mixed-bed ion exchange tower equipped with an ion exchange resin that can be separated into upper and lower layers by backwashing, the ion exchange tower is set in the upper part of the lower ion exchange resin layer separated by backwashing. The transfer water is spouted from the transfer water spouting part, and a normal resin withdrawal port is provided near the spouting part;
In addition, when pulling out the resin using the ion exchange resin layer above the spouting part or the sub-drawing port for the resin provided near the interface between the upper and lower layers, after pulling out the resin above from the sub-drawing port. , a method for transferring ion exchange resin, characterized in that the resin above the normal drawing port is pulled out from the normal drawing port. 2. The method according to claim 1, wherein the resin drawing step is performed by stopping drainage and introducing pressurized air from an air supply/exhaust port.