JP2024005982A - Membrane separation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane separation apparatus capable of being operated while maintaining a cleanliness of the system and the separation performance of the membrane separation means.

SOLUTION: A membrane separation apparatus comprises membrane separation means that supplies raw water and separates it into permeate water and concentrated water, estimating means for estimating the degradation state of the separation performance of the membrane separation means, and determination means for determining the cause of degradation in the separation performance. When the degradation state estimated by the estimating means exceeds a predetermined level, the cause of degradation is determined by the determination means.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a membrane separation device that achieves cleanliness within the system and has highly stable operating performance.

The Central Dialysate Supply System (CDDS), which centrally prepares the dialysate needed for dialysis treatment, is currently the mainstream system in Japan. Preparing a large amount of dialysate requires a large amount of purified water for dilution, and this water is mainly used as raw water, such as tap water, and purified water is purified using a purified water production device that uses membrane separation technology using reverse osmosis. It has gained. There is an ever-increasing demand for purification of purified water that is used to dilute dialysate that comes into contact with a patient's blood through a hollow fiber membrane inside a blood purifier such as a dialyzer.

In order to obtain highly clean purified water, it is important to regularly disinfect these membrane modules with hot water and clean them with low-concentration chemical solutions, but once contamination has progressed, In this case, there is a possibility that the inside of the system may not be sufficiently cleaned even after disinfection and cleaning.

In order to prevent contamination within the system, it is possible to adopt a structure in which water is less likely to accumulate or stagnate in the flow path. For example, in Patent Document 1, one end side of the water collection pipe of the RO membrane module and the water storage tank are connected by a permeated water line, the water storage tank and the other end side of the water collection pipe of the RO membrane module are connected by a permeated water return line, and the permeated water A purified water production apparatus is disclosed in which a circulating cleaning line is formed by a line, a water collection pipe, and a permeated water return line.

Further, Patent Document 2 discloses a diagnostic device that detects malfunction of a reverse osmosis system due to blockage of an RO membrane and determines countermeasures.

Japanese Patent Application Publication No. 2012-106188 Japanese Patent Application Publication No. 2019-202305

As mentioned above, membrane separation devices using RO membranes and the like are required to operate stably while keeping the inside of the system clean. Therefore, an object of the present invention is to provide a membrane separation device that can be operated while maintaining the cleanliness inside the system and the separation performance of the membrane separation means.

In order to solve the above problems, the membrane separation device according to the present invention includes a membrane separation means that supplies raw water and separates it into permeated water and concentrated water, and an estimation that estimates the state of deterioration of the separation performance of the membrane separation means. and a determining means for determining the deterioration factor of the separation performance,
The deterioration factor is determined by the determining means when the deterioration state estimated by the estimating means exceeds a predetermined level.

According to the membrane separation device of the present invention, while monitoring separation performance during operation, when it is estimated that separation performance has deteriorated, the cause of the deterioration is determined according to a predetermined procedure and appropriate measures are taken. becomes possible.

In the membrane separation device of the present invention, it is preferable that the deterioration factors are at least classified into foreign matter deposition on the membrane surface, membrane clogging, and membrane tearing. By classifying the deterioration factors into these three or more items, measures for performance recovery can be routinely implemented.

The membrane separation apparatus of the present invention is preferably configured to perform an operation for removing the deterioration factor determined by the determination means. By incorporating appropriate countermeasures into the operation control program in advance for each identified deterioration factor, it is possible to automatically take measures to restore performance to a certain extent when performance deterioration occurs, without the need for workers to rush to the site. can.

In the membrane separation apparatus of the present invention, the membrane separation means includes a plurality of membrane modules, the estimation means and the determination means are provided for each of the membrane modules, and the deterioration factor removal operation is performed for each of the membrane modules. can be configured to perform. By adopting such a configuration, even if the membrane separation means is composed of multiple membrane modules, if the performance of the entire membrane separation device deteriorates, any membrane module will fail. This makes it possible to identify whether or not the system is operating properly, and to appropriately implement performance recovery measures.

In the membrane separation apparatus of the present invention, it is possible to configure the removal operation to include stopping the supply of the raw water to the membrane module. When the membrane separation means is composed of a plurality of membrane modules, it is possible to stop supplying raw water to the membrane module in which the problem has occurred and continue membrane separation using the remaining membrane modules. In this case, some of the membrane modules will have to be discontinued, so it is recommended that you design the equipment in advance to allow a margin for the raw water load, or install spare membrane modules so that they can be used at any time. It can be used in place of a malfunctioning membrane module.

In the membrane separation apparatus of the present invention, it is preferable that the estimating means includes at least a pressure gauge, a conductivity meter, and a flowmeter. Membrane rupture can be detected by an increase in the electrical conductivity of permeated water, and foreign matter accumulation and clogging can be estimated from the degree of increase in differential pressure and decrease in flow rate.

In the membrane separation device of the present invention, it is preferable that the permeated water and the concentrated water flow in the same direction across a membrane surface of the membrane separation device. When a water collection pipe with both ends open is used in a so-called external pressure type membrane separation device, this type of parallel flow operation can increase the raw water pressure upstream of the water collection pipe than when using countercurrent flow. , stagnation in the water collection pipe can be effectively prevented.

In the membrane separation device of the present invention, it is preferable that the flow directions of the permeated water and the concentrated water change. More specifically, it is preferable that the operating state and the resting state are repeated intermittently, and the flow directions of the permeated water and the concentrated water change each time the operating state is changed from the resting state to the operating state. By switching the flow directions of permeated water and concentrated water in this manner, it is possible to suppress unevenness in the raw water load applied to the membrane separation means and prevent clogging of the membrane due to scale adhesion. Further, foreign matter deposited on the membrane surface can be washed out of the system by changing the flow direction.

The membrane separation device of the present invention is suitable when the membrane separation device consists of a reverse osmosis membrane. In a membrane separation device that produces purified water for diluting dialysate, cleaning of the system is particularly required, and the application of the present invention can satisfy such a requirement.

According to the present invention, since it is possible to grasp the deterioration status and deterioration factors of the separation performance of the membrane separation means, it is possible to maintain the cleanliness in the system and the separation performance of the membrane separation means.

1 is a schematic flow diagram of a membrane separation device according to one embodiment of the present invention. 2 is a schematic flow diagram showing a case where permeated water and concentrated water flow in opposite directions in the membrane separation device of FIG. 1. FIG. FIG. 3 is a schematic flow diagram of a membrane separation device according to another embodiment of the present invention. 4 is a schematic flow diagram showing a case where permeated water and concentrated water flow in opposite directions in the membrane separation device of FIG. 3. FIG. 3 is a schematic flow diagram for explaining the behavior when deterioration occurs in the membrane module in the membrane separation device of FIG. (C) shows the case where deterioration occurs due to clogging, and (C) shows the case where deterioration occurs due to membrane tearing.

Below, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic flow diagram showing the configuration of a membrane separation apparatus 1 according to an embodiment of the present invention, and FIG. 2 shows a case where permeated water and concentrated water flow in opposite directions. A broken line indicates a channel in which water is not flowing due to the valve being closed, and a solid line indicates a channel in which water is flowing. Also, the closed locations of the three-way valves 3, 13, 23, 33, and 43 are shown in black. In both FIGS. 1 and 2, raw water supplied to the membrane separator by the RO pump 2 flows into the first membrane module 4 through the three-way valve 3, and becomes the first RO permeated water and the first RO concentrated water. separated. The first RO retentate flows into the second membrane module 5 and is separated into the second RO permeate and the second RO retentate. The first RO permeated water flows out from the water collection pipe 4a of the first membrane module 4, and the second RO permeated water flows out from the water collection pipe 5a of the second membrane module 5, passes through the three-way valves 13 and 23, and then passes through the permeated water tank 6. is stored in A portion of the second concentrated water is discharged outside the system through the three-way valves 33 and 43, and a portion is returned to the suction side of the raw water pump 2 through the check valve 7.

The permeated water tank 6 is equipped with a sterilizing lamp 8 and a liquid level gauge 9, and is sent to a dialysate manufacturing apparatus (not shown) by a purified water pump 10.

A pressure gauge 16 and a flow meter 17 are provided at the inlet and outlet of the first membrane module 4 and the second membrane module 5, respectively. A conductivity meter may also be installed at the location where the flow meter 17 is installed.

FIG. 3 is a schematic flow diagram showing the configuration of a membrane separation device 11 according to another embodiment of the present invention, and FIG. 4 shows a case where permeated water and concentrated water flow in opposite directions. In both FIGS. 3 and 4, the raw water supplied to the membrane separator by the RO pump 2 flows into the first membrane module 14 through the three-way valve 3, and becomes the first RO permeated water and the first RO concentrated water. Separated. The first RO concentrated water flows into the second membrane module 15 and is separated into the second RO permeated water and the second RO concentrated water, but the first RO permeated water flowing out from the water collection pipe 14a flows into the second membrane module 15. The flow differs from the flow shown in FIG. 1 in that the permeated water flows into the water collection pipe 15a, merges with the second RO permeated water within the water collection pipe 15a, and flows out from the water collection pipe 15a and is stored in the permeated water tank 6. Similar to the flows in FIGS. 1 and 2, a portion of the second RO concentrated water is discharged outside the system via the three-way valves 33 and 43, and a portion of the second RO concentrate passes through the check valve 7 and enters the suction side of the raw water pump 2. be returned.

Continuous operation is possible for the membrane separators 1 and 11, but if the capacity of the permeated water tank 6 is larger than the amount of permeated water consumed, intermittent operation that repeats the start and stop of water sampling is possible. You may do so. In this case, water sampling is started with the flow direction of permeated water and concentrated water as shown in FIG. 1 or 3, and when the permeated water tank 6 is filled with permeated water, water sampling is stopped, and When the liquid level drops to a predetermined level, the flow direction of the permeated water and concentrated water can be changed to the direction shown in FIG. 2 or FIG. 4, and water sampling can be started. If the membrane module is operated while changing the flow direction of the permeated water and concentrated water at any time in this way, the unbalanced load on the membrane module can be alleviated and the life of the membrane can be extended.

FIG. 5 is a schematic flow diagram for explaining the behavior when deterioration occurs in any of the membrane modules in the membrane separation apparatus of FIG. (B) shows deterioration due to membrane clogging, and (C) shows deterioration due to membrane tearing.

In order to detect deterioration (A) to (C) of the membrane modules, a pressure gauge 16, a conductivity meter, a flow meter 17, etc. are installed on the inlet side, outlet side, and water collection pipe outlet side of each membrane module. Deterioration status can be monitored.

For example, if foreign matter 18 is deposited on the raw water inlet side as shown in Fig. 5(A), fluctuations in pressure and flow rate will occur. The deterioration status monitoring program is set so that the deterioration (A) estimation flag is set. After continuing operation and repeating the start and stop of water sampling a predetermined number of times, if the fluctuation range of pressure or flow rate falls below the predetermined value, deterioration (A) due to foreign matter accumulation on the membrane surface will occur and recovery will occur. It is determined that the If the fluctuation range of pressure and flow rate still exceeds the specified value even after starting and stopping water sampling a predetermined number of times, drain the raw water forcefully through the raw water line for a short period of time while water sampling is stopped. If the fluctuation width of the pressure and flow rate falls below a predetermined value after performing the flushing cleaning, it is determined that the cause of the deterioration is deterioration (A) due to the accumulation of foreign matter on the membrane surface, and that the film has already recovered.

Furthermore, as shown in FIG. 5(B), for example, when membrane clogging occurs due to scale 19 or other fouling 20, pressure and flow rate fluctuations occur, so the range of fluctuations exceeds a predetermined value. In this case, the deterioration status monitoring program is set so that a flag for estimating deterioration (B) due to membrane clogging is set. In the case of deterioration due to membrane clogging (B), it cannot be expected to recover naturally even if operation continues as in the case of deterioration due to foreign matter deposited on the membrane surface (A), so it is necessary to start and stop water sampling. If the fluctuation width of the pressure or flow rate falls below the predetermined value after repeating this a predetermined number of times or after performing the short-time flushing cleaning described above, the flag for estimating deterioration due to membrane clogging (B) is canceled. do. If the estimated flag for deterioration due to membrane clogging (B) remains on for a predetermined period of time, it is determined that the deterioration factor is deterioration due to membrane clogging (B), and a message to that effect is displayed on the monitor screen. Display. It is also possible to send an alarm to the maintenance company of the membrane separation device using communication means.

Furthermore, as shown in FIG. 5(C), for example, when a membrane rupture 21 occurs, the conductivity of the permeated water increases in addition to fluctuations in pressure and flow rate, so that the conductivity exceeds a predetermined value. In this case, the deterioration status monitoring program is set so that a flag for estimating deterioration (C) due to membrane tearing is raised. Factors that can cause the conductivity of permeated water to increase include, in addition to membrane rupture, the occurrence of electrical signal noise and sudden changes in raw water quality or pressure. However, if the conductivity continues to increase for a certain period of time, When water sampling is stopped, a compressed air pump is used to send air from the permeated water line to the membrane module, and if the pressure cannot be maintained when the compressed air pump is stopped with water expelled from the water collection pipe, the cause of deterioration may occur. It is determined that the deterioration (C) is due to membrane tearing, and a message to that effect is displayed on the monitor screen. It is also possible to send an alarm to the maintenance company of the membrane separation device using communication means.

In addition, while monitoring the deterioration status of the membrane as described above, if it is determined that the deterioration factor is due to the accumulation of foreign matter on the membrane surface (A) or deterioration due to membrane clogging (B), the deterioration factor will be determined. A washing step can also be carried out as a removal operation. For example, a chemical cleaning process in which scale is removed from the raw water line of a membrane separator using a chemical solution such as citric acid, acetic acid, or lactic acid, or a bubble cleaning process in which the raw water line is cleaned with water mixed with microbubbles is performed to remove deteriorated membranes. Performance can be recovered. When carrying out the water sampling process again after carrying out the cleaning process, it is also possible to follow the above-mentioned deterioration status monitoring program to check whether the deterioration factors have been removed and the performance has been restored.

Furthermore, instead of performing the above-mentioned cleaning process, when it is determined that the deterioration factor is deterioration (C) due to membrane tearing, the supply of raw water to the membrane module can be stopped as an operation to remove the deterioration factor. . If a membrane rupture occurs, performance recovery cannot be expected even after cleaning, so the inflow and outflow valves around the membrane module are shut off, the use is stopped, and a spare membrane module that has been kept on standby is removed. It is possible to start using it. Alternatively, if the design allows for a margin in the number of membrane modules for the raw water load, it is possible to discontinue the use of some membrane modules and collect water by using only the remaining membrane modules to cover the raw water load. may continue.

INDUSTRIAL APPLICABILITY The present invention can be widely used as a membrane separation device that requires highly stable operating performance.

1, 11 Membrane separation device 2 RO pump 3, 13, 23, 33, 43 Three-way valve 4, 14 First membrane module 4a, 5a, 14a, 15a Water collection pipe 5, 15 Second membrane module 6 Permeated water tank 7 Check Valve 8 Germicidal lamp 9 Level gauge 10 Purified water pump 16 Pressure gauge 17 Flow meter 18 Foreign object 19 Scale 20 Fouling 21 Rupture

Claims (10)

It consists of a membrane separation means for supplying raw water and separating it into permeated water and concentrated water, an estimation means for estimating the state of deterioration of the separation performance of the membrane separation means, and a determination means for determining the cause of the deterioration of the separation performance. ,
A membrane separation apparatus characterized in that when the state of deterioration estimated by the estimating means exceeds a predetermined level, the determining means determines the deterioration factor. The membrane separation device according to claim 1, wherein the deterioration factors are at least classified into foreign matter deposition on the membrane surface, membrane clogging, and membrane tearing. The membrane separation apparatus according to claim 2, wherein an operation for removing the deterioration factor determined by the determination means is performed. 4. The method according to claim 3, wherein the membrane separation means includes a plurality of membrane modules, the estimation means and the determination means are provided for each of the membrane modules, and the deterioration factor removal operation is performed for each of the membrane modules. membrane separation equipment. The membrane separation apparatus according to claim 4, wherein the removal operation includes stopping the supply of the raw water to the membrane module. The membrane separation apparatus according to any one of claims 1 to 5, wherein the estimating means includes at least a pressure gauge, a conductivity meter, and a flow meter. The membrane separation device according to claim 1, wherein the permeated water and the concentrated water flow in the same direction across a membrane surface of the membrane separation device. The membrane separation device according to claim 1 or 7, wherein the flow directions of the permeated water and the concentrated water change. The membrane separation device according to claim 8, wherein the operating state and the resting state are repeated intermittently, and the flow directions of the permeated water and the concentrated water change each time the operating state is changed from the resting state to the operating state. The membrane separation device according to claim 1, wherein the membrane separation device comprises a reverse osmosis membrane.

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