JPS60132691A - Removal of suspended substance in packed bed - Google Patents

Abstract

PURPOSE:To shorten separation time and to reduce the amount of a waste solution, by performing an air-water scrubbing process and the washing process of an intermediate water collection apparatus to be performed after a drain process and an air scrubbing process. CONSTITUTION:Water is drained in a drain process so as to bring the level of water to the level L1 of an intermediate water collection apparatus 15. Subsequently, air scrubbing is performed in an air scrubbing process in such a way that air is introduced from a pipe 8 through a lower water collection apparatus 5 and exhausted through an upper water collection apparatus 6. In the next step, an air-water scrubbing process III is performed to convey heavy clad high in a precipitation speed from the lower part of a resin bed to the intermediate water collection apparatus 15 by a high flow speed upward stream of air and water and to remove the same through a pipe 16. After the process III is perofrmed for a definite time, the washing process IV of the intermediate water collection apparatus 15 and the process III is subsequently performed again. By repeating processes III, IV, if necessary, the efficient removal of clad and the prevention of the accumulation of the resin to the intermediate water collection apparatus 15 are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for removing suspended substances such as iron oxides trapped in a packed bed by passing raw water through the bed.

[Prior art]

When purifying water by passing water through a packed bed, especially a packed bed of ion exchange resin, various methods are available to remove crud such as iron oxide with a high specific gravity trapped in the packed bed. Proposed.

For example, in a condensate demineralization system for a power generation boiler, after water is passed through the demineralization tower for a certain period of time, the ion exchange resin is transferred to the regeneration tower, and the ion exchange resin is backwashed to remove shifrad. It is being said.

The conventional method will be explained below based on the drawings.

FIG. 1 is a schematic diagram showing a commonly used crud removal method, where 1 is a regeneration tower, 2 is an ion exchange resin layer in a settled state, 3 is an ion exchange resin layer in a scrubbed state, 4 is an ion exchange resin layer in a backwashed state, 5 is a lower water collection device, 6 is an upper water collection device, 7, 8, 9.10 is piping for introducing or draining air or water, 11゜12,
Reference numerals 13 and 14 indicate the valves provided on the piping, (1) indicates the draining process, (■) indicates the air scrubbing process, and Qll) indicates the backwashing process.

The following will explain based on FIG. 1, but (II) in FIG.
As for @5, only the parts necessary for explanation are labeled.

In the method shown in FIG. 1, after the ion exchange resin (hereinafter simply referred to as resin) is transferred to the regeneration tower 1,
Then open the valve 13 of the pipe 9 and force air through the pipe 9 to drain the water through the pipe 7 until the water surface reaches a position L1 on the upper part of the resin layer 2 (Fig. 1K), and then open the valve 11 and the valve 1.
3 was closed, valves 12 and 14 were opened, and air was exhausted from the pipe 10 via the upper water collection device 6, while air was introduced into the lower part of the resin layer from the pipe 8 through the lower water collection device 5, thereby scrubbing the resin. After that (Fig. 1 ■), close the valve 12, open the valve 11, and open the pipe 7.
The backwash water is introduced into the lower part of the resin layer through the lower water collection device, and the resin is backwashed while the backwash wastewater is discharged through the upper water collection device 6 and into the pipe 10 (Fig. 1 ■). . In this method, the steps (drain-air scrubbing-backwashing) are repeated about three times to increase the crud removal rate.

In this method, (1) there is a limit to the flow rate of backwash water (ma
x, approximately 15 m/h), and the time required to separate the cladding is long because the backwash water is discharged from the water collection device at the top of the regeneration tower (2) there is a restriction on the flow rate of the backwash water. Because of this, heavy cladding is difficult to transport to the top of the tower.
(3) Since air scrubbing is performed again after backwashing, it is necessary to drain the water, which has disadvantages such as an increase in the amount of waste liquid.

FIG. 2 is a schematic diagram for explaining an improved method for removing heavy crud; the apparatus itself and the reference numerals are the same as those shown in FIG. 1; Only the symbols necessary to explain the method have been entered. In FIG. 2, (1) shows the Drevi process, (II) shows the air scrubbing process, Tsukuda) shows the rapid drain process, and (B) shows the water filling process.

In Fig. 2, the drain step (1) is the same as that explained in Fig. 1, but after air scrubbing for a certain period of time in the air scrubbing step (ll), the resin is removed by the air introduced from the bottom. While the layer is being developed, the valves 12 and 14 are closed to stop the introduction of air from the tube 8 into the resin layer 3, and at the same time, the valves 11 and 13 are suddenly opened and the air is forced through the tube 9 and passed through the tube 7. It drains water all at once (
Rapid drain process in Figure 2 ■). Then close valve 11 and close valve 1.
4 is opened and water is poured from the pipe 10 to the height of (water filling process shown in Fig. 3), and then the process returns to the air scrubbing process. Although this method is effective for removing heavy crud, the amount of water discharged per step is small (only the difference between Ll and L in Figure 2 can be drained), and therefore air scrubbing, rapid draining, and water filling ( It is necessary to repeat steps n) to M about 10 to 30 times, making the process complicated.

Figure 3 is for explaining a method that is an improvement on the method shown in Figure 1 and drains water from an intermediate water collection device after backwashing. They have the same meaning, 15 is an intermediate water collection device, 16 is its piping, 17 is a valve, (1) is a drain process, (■) is an air scrubbing process, @) is a backwash process, (transfer) shows the drain process from the intermediate water collection device.

In the method shown in Figure 3, the drain process (■) and (n
) The air scrubbing process is the same as the method shown in FIG.
is closed, valves 13 and 17 are opened, and air is pumped through pipe 9 to remove the backwash water existing above from the intermediate water collection device to the intermediate water collection device 1.
5 and drain pipe 16. Although this method reduces the time required to separate the crud and requires less waste liquid than the method shown in FIG. 1, the removal of heavy crud is not as sufficient as the method shown in FIG.

FIG. 4 is a diagram for explaining a method improved from the method shown in FIG. 3, in which each symbol has the same meaning as the symbol shown in FIG. ) indicates the air scrubbing process, (IIl) indicates the backwashing process, (F) indicates the draining process from the intermediate water collection device, and (G) indicates the water filling process.

In the method shown in FIG. 4, in the backwash step (III), the valve 14 is closed and the inside of the regeneration tower 1 is brought into a pressurized state by introducing backwash water without exhausting through the pipe 10.
When a certain pressure is reached, the valve 17 is opened and this pressure is used to drain water from the intermediate water collection device 15 and the pipe 16 (step
). Next, valve 17 is closed, valves 13 and 14 are opened, and while exhausting air from pipe 9, make-up water is supplied through pipe 14, and then (
It) to (V) are repeated.

In the method shown in Figure 4, the backwash water is not exhausted when it is introduced, so even if the initial backwash flow rate is increased, the flow rate of the backwash water becomes extremely small as the pressure inside the column increases. If the crud is heavy, it will end up at the bottom of the intermediate water collection device and cannot be discharged. To avoid this, special consideration is required for the backwash water supply pump, which is expensive in terms of equipment.

Depending on the conventional backwashing method described above, particles are difficult to transport as the backwash water flows upward to the top of the resin layer, further beyond the resin layer to the discharge outlet at the top of the tower or to the water collection device in the middle of the tower. For heavy cladding with a large diameter, the method shown in FIG. 2 is preferred.

[Object of the Invention] An object of the present invention is to provide a method for separating heavy cladding, which improves the drawbacks of the above-mentioned conventional methods, requires a short separation time, and produces a small amount of waste liquid.

[Structure of the Invention] The present invention provides a method of scrubbing while simultaneously introducing air and water from the lower part of the packed bed, and (1) passing through the filler provided on the surface layer of the packed bed that is expanded by the scrubbing. (2) discharging and discharging water from an intermediate water collection device having a structure that allows only suspended matter to pass through without causing any This is a method for removing suspended matter in a packed bed, which is characterized by repeatedly carrying out both steps, including a step of only evacuation from an evacuation device.

In order to improve the drawbacks of the conventional method as described above, the present inventors have developed a method that is effective even for heavy crud with a large particle size, that is, crud with a high sedimentation rate, and that the separation time is short. The present invention was developed as a result of intensive research into a crud removal method that requires less waste liquid.

The method of the present invention will be explained based on FIGS. 5 and 6. Figure 5 shows the case where one series of intermediate water collection device is used, Figure 6 (d2
The case where two systems are used is shown. Reference numerals 1 to 17 in FIG. 5 have the same meanings as the reference numerals shown in FIG. 3, and in FIG.
, 15b is an intermediate water collection device, 16a and 16b are its piping,
17a and 17b indicate valves, and other symbols have the same meanings as those shown in FIG. 3. In FIG. 5, in the drain step (1), the level of water is drained at the level (Lt)t of the intermediate water collecting device 15. Then air scrubbing,
Air is introduced from the pipe 8 through the lower water collection device 5 and is carried out while being exhausted through the upper water collection device 6 (step n). The air scrubbing step (n) separates the crud trapped in the resin from the resin and atomizes the large crud. Step (I) (■) is a conventional method. The air-water scrubbing and intermediate water collection device cleaning steps of the present invention are then carried out. The present invention is based on simultaneously introducing air and water from the lower water collection device 5 and discharging the air and water from the intermediate water collection device 15 through the valve 17 and pipe 16. is transported from the lower part of the resin layer to the intermediate water collection device 15 by the upward flow of air and water at a high flow rate, and is transferred to the pipe 16.
It is removed through. In the air-water scrubbing step Q[l) shown in FIG. 5, the valves 13 and 14 are closed, so no exhaust is carried out from the top of the tower, and therefore the flow of water and air is always concentrated in the intermediate water collection device 15. The water is then discharged from the intermediate water collecting device 15 to the outside of the system via a pipe 16.

In normal backwashing using only water, when draining water from an intermediate water collection device, resin accumulates in the intermediate water collection device, making it difficult to drain the crud. However, in the case of the present invention in which water and air are simultaneously introduced for scrubbing, the resin layer, especially its surface layer, is shaken violently, so even if resin accumulates in the dust intermediate water collection device, this accumulated resin layer will Experiments have confirmed that there is no problem in discharging crud because the "surface" of the intermediate water collection system is constantly renewed, and the drainage and exhaust surfaces of the intermediate water collection system are constantly renewed.

The appropriate flow rate of air from the lower water collection device is 15 to 50 m/h, which is smaller than the LV50 to 1oo/h that is normally used in the air scrubbing process, and the flow rate of water is L.
V5-15m/h is preferable. In the method of the invention, the transport and removal of crud is carried out not only by water but also by air, and the water flow rate does not have to be as high as in conventional backwashing.

Further, to explain in detail how the crud is removed, water and air are discharged from the lower half of the cross section of the pipe of the intermediate water collection device, and the majority is water. On the other hand, air is mainly exhausted from the upper half of the tube's cross section. In addition, the surface layer of the resin layer may exhibit bumping movements due to scrubbing, and at this time, a phenomenon in which resin is gradually deposited on the upper half of the cross section of the tube is observed. /h, which increases as the flow rate increases, but even under the design conditions of the normally used intermediate water collection device, no problem arises in terms of air discharge between 20 and 30 FM/h. In other words, in the lower half of the cross section of the pipe, the surface for drainage and exhaust has been updated by the developed resin layer itself, whereas in the upper half, there is a problem in the discharge of water and air during the process of ([lI)]. Although it does not become a problem, resin accumulates little by little.

Furthermore, it has been found through experiments that in the water-air scrubbing process, crud is concentrated in a region approximately 100 to 300+ meters from the surface of the developing resin layer. Therefore, in order to efficiently remove the crud from this area and to prevent resin from accumulating in the upper half of the pipe cross-section of the intermediate water collection device, a water-air scrubbing step (dll) is carried out for a certain period of time (3~
10 minutes), the drain valve 17 is closed to stop drainage and exhaust from the intermediate water collection device, and the valve 14 is opened to only exhaust air from the upper water collection device 6 and pipe 10 at the top of the tower to remove the developing resin layer. 100-300III+ from intermediate water collection device
The cleaning step (b) of the intermediate water collecting device is carried out by raising it to the height (L2 position), then the valve 14 is closed, and the valve 17 is closed.
By opening the door and performing the water-air scrubbing step (01l) again, 100% of the difference between L2 and Ll in Figure 5 is removed.
The part where the ~300-crud is concentrated is discharged. By repeating the step II)-(Foundation) as necessary, it is possible to efficiently remove the crud and prevent the resin from accumulating in the intermediate water collecting device.

In this way, in the air-water scrubbing process, water and air are continuously introduced from the lower water collection device 5, so in normal water backwashing, water and air are present at the bottom of the resin layer and are difficult to discharge.
Heavy crud with a large particle size is also carried by the upward flow of air and water to the upper part of the resin layer, that is, to the intermediate water collecting device 15, and is efficiently removed.

Figure 6 shows the case where two intermediate water collection systems are provided, and the water flow rate L is higher than that in Figure 5.
V6~2 s m/h N air flow rate LV30~70
Can be used at m/h. When running at such a high flow rate, a large amount of resin will accumulate in the intermediate water collection device, but since there are two series of intermediate water collection devices and they are used alternately, one series will perform exhaust and drainage, and the resin will accumulate in the intermediate water collection device. Even though the amount of resin accumulated during that time has been loosened, the "surface" of one series has been updated to be sufficient for drainage and exhaust, making it fully usable. Therefore, the air-water scrubbing step Qll) shown in FIG. 5 is performed more effectively and the time for this step is reduced accordingly. That is, in FIG. 6, when the valve 17a is opened and air and water are being discharged from the intermediate water collecting device j5a through the pipe 16a, the resin layer concentrated and deposited on one intermediate water collecting device 15-b is loosened, When it becomes difficult for crud to come out from j5-a, the pulp is simply changed, that is, 17a is closed and 171) is opened to discharge air and water from 15-b. It is more effective to discharge the crud if the cutting and replacing time is short, about every 3 to 5 minutes. Intermediate water collection device used in Figures 5 and 6
5.15a, 151) can be simply a single piece of piping, such as the freeboard drain used in conventional mixed bed systems, with a Saran net, etc., equivalent to 35 to 60 mesh attached, or A water collection pipe with a slit of ~400 μm may be sufficient.

The present invention will be explained in detail below based on the drawings.

First, FIG. 5, which uses one series of intermediate water collection devices, will be explained. The drain process and air scrubbing process of (1) and (It) are the same as the conventional method, and the
The water is drained to a height of 0 to 400 ma (Step ①), and then air scrubbing (If) is performed.

The air flow rate at this time is LV50-100 m/h and the air pressure is 2-3 Kgt 7cm2. Next, proceeding to the air-water scrubbing step ([1) of the present invention, the air inflow valve 12 of the lower water collection device 5 is opened, and the water flow valve 11 of the intermediate water collection device 15 is opened, and the drain valve 17 of the intermediate water collection device 15 is opened. The tank is opened and air and water are introduced into the regeneration tower 1 through the lower water collection device 5 through the pipes 8 and 7, and scrubbing with air and water is performed while draining and exhausting from the intermediate water collection device 15. At this time, no exhaust is performed from the top of the tower. Air flow rate is LV15-50m
It is better to set the air inlet valve 12 to about 1/h and (It) lower than the flow rate during air scrubbing, but depending on the degree of contamination of the target resin, the properties of the cladding of the resin layer, the type of resin, etc.
The installation may adjust the flow rate of air in each step (Il), Qll) and QV) as appropriate.

The flow rate of sluicing water is approximately LV3 to 15 m/h.

When performing the step (Tsukuda), air and water are discharged only from the intermediate water collection device, so some resin accumulates around the intermediate water collection device, but since air is introduced, the surface layer of resin layer 3 As the surrounding area is considerably undulated, the resin that has been deposited once breaks down one after another, and the deposited part is the upper half of the pipe cross section of the intermediate water collection device 15, as mentioned above, and the amount is small, making it difficult for drainage and exhaust. There are almost no problems with μ.

However, in order to ensure safe discharge of the crud, after carrying out step Q[l) for 3 to 10 minutes, the drain valve 1 of the upper water collection device 6
4 is opened, and the drain valve 17 of the intermediate water collection device 15 is closed to proceed to the cleaning step of the intermediate water collection device, which is the step (opening).

During the (transfer) process, sluicing water and air continue to be introduced from the lower water collection device, causing the water level in the tower to rise. The surface layer of the resinous structure layer 3 is higher than the position of the intermediate water collection device 15. The step (transfer) loosens the resin accumulated in the intermediate water collection device 15, and also concentrates the cladding densely on the upper part of the developing resin layer, so that when repeating the next step (III), the cladding is efficiently removed. The difference between #) L2 and Ll is sufficient to be 1oo to 3oow+, and the
A short time of ~5 minutes is sufficient.

Then, return to the air-water scrubbing step of @).

Repeat the steps of @) and (goods) 3 to 10 times as necessary. After the final (rotation) step is completed, the valve 12 of the air introduction pipe 8 is closed, and only backwash water is passed through the lower water collection device to carry out backwashing, which also serves as a water filling step, to complete the crud removal operation.

Next, a case shown in FIG. 6 in which two lines of intermediate water collection devices of the present invention are provided will be described.

The draining process and air scrubbing process of (1) and (I[) are the same as those shown in FIG. In the air-water scrubbing step of step 011), the air inflow valve 12 and sluicing water flow valve 11 of the lower water collection device 5 are opened and the fifth
Air and sloshing water are introduced at similar flow rates as described for the figure. Then, the drain valve 17-a of the intermediate water collection device 15-a is opened for 3 to 5 minutes to drain and exhaust water through the pipe 16a, and when it becomes difficult for crud to come out, the drain valve 17-a is closed and another intermediate water collection device is opened. Drain valve 17- of water device 15-b
Let b be open. 17-a and 17-b every few minutes like this
Opens and closes to efficiently discharge air and water, that is, discharge crud.

The intermediate water collecting devices 15-a and 15-b may be set at positions 200 to 500 days higher than the settled surface layer of the resin layer 2. The setting positions of 15-a and 15-b may be at the same height, or may be set at different heights. When providing a height difference, 15-a is 200 to 300+n++ from the surface layer of resin layer 2.
The position is determined so as to be at the + position, that is, the position where the cladding is peeled from the resin and the cladding is refined in the air scrubbing of (II) and the resin slurry is concentrated.

The other 15-b is installed at 300~500cm from the resin layer 20 surface layer and the upper part of 15-a to increase the expansion rate of the resin layer so that the crud can be discharged well during air-water scrubbing. It is preferable to do so. Then, the ([l)-〇)=(turn) process is repeated as necessary, and finally, normal backwashing is performed, which also serves as a water filling process, to complete the crud removal operation. Next, Table 1 shows the difference in effect between the conventional method shown in FIGS. 1 and 2 and the method of the present invention shown in FIGS. 5 and 6.

Table-1 Note Cation regeneration tower 1600φ Cation resin 26
00t anion regeneration tower 1200φ anion resin 1
The value of 400 in Table 1 is the total of both regeneration towers.

Table 1 shows the results when water is passed through a thermal power plant for 30 consecutive days during normal operation and then transferred from the demineralization tower to the regeneration tower, and the cation resin is removed in the cation regeneration tower and the anion resin is removed in the anion regeneration tower. This shows the results. In the case of the method of the present invention, the cleaning time, the amount of cleaning waste water, and the amount of air are significantly reduced. Also, after these washings, when both resins were mixed and transferred to the desalination tower, the iron concentration in the resin transfer water was the first.
The conventional method shown in the figure has a concentration of 35 ppm (as Fe), while the conventional method shown in FIG. 2 and the method of the present invention shown in FIGS.
e) was as follows. From the above results, it can be seen that the method of the present invention can remove crud in a shorter time and with a smaller amount of water and air than the conventional method, and has a better crud removal rate.

The present invention has the same crud removal rate as the conventional method shown in Fig. 2, which is said to be effective in removing the heaviest crud, and the operation method is simpler and the amount of air used is smaller. It's gone, and the effect is great.

[Brief explanation of drawings]

1, 2, 3 and 4 are drawings for explaining the conventional method, and FIGS. 5 and 6 are drawings for explaining the method of the present invention. 1... Regeneration tower, 5... Lower water collection device, 6... Upper water collection device, 15, 15a, 15b... Intermediate water collection device Patent applicant: Ebara Infilco Co., Ltd. Agent Shodo Inoue Katsura Yoshimine

Claims (1)

[Claims] 1. While scrubbing is performed while simultaneously introducing air and water into the lower part of the packed bed, (1) the filling material provided on the surface layer of the packed bed being expanded by the scrubbing; (2) stopping drainage and exhaust from the intermediate water collection device and removing the upper part of the intermediate water collection device; 1. A method for removing suspended matter in a packed bed, the method comprising repeatedly carrying out both steps of exhausting only from an exhaust device installed in the bed. 2. The method for removing suspended matter according to claim 1, wherein two lines of intermediate water collection devices are provided, and drainage and exhaust are carried out alternately from each line.