JP4979964B2 - Chemical solution injection device for water treatment equipment - Google Patents

Description

  The present invention relates to a chemical liquid injection device for a water treatment device by membrane filtration, in which contaminants contained in raw water, such as waterworks, sewerage, industrial water or wastewater treated water, are separated and removed by a filtration membrane and purified. The present invention also relates to a chemical liquid injection device for sterilizing raw water and a chemical liquid injection device for a chemical treatment backwash type water treatment device.

  As a method for removing pollutants in the water to be treated, a water treatment method using membrane filtration is well known. In this water treatment using membrane filtration, as the operation continues, an adhering layer of pollutants is formed on the surface of the filtration membrane, clogging, fouling such as blockage of the flow path due to solid matter, and filtration performance decreases. There is a problem to do.

  Therefore, in the operation cycle, physical cleaning or chemical cleaning is performed after the filtration process for a predetermined time to reduce fouling. Physical cleaning includes backflow cleaning (backwashing) that reverses the treated water after membrane filtration, flushing by water flow on the primary side of the membrane, and air scrubbing that vibrates the membrane with air. Has been removed. On the other hand, chemical cleaning is a method of removing substances that cannot be removed by physical cleaning by decomposing or dissolving them with chemicals. For example, water treatment using backwashing with chemicals such as sodium hypochlorite, sulfuric acid and hydrochloric acid added. A method has been proposed (see Patent Document 1).

  FIG. 6 shows a schematic system diagram of an example of a general filtration membrane cleaning method using a conventional chemical enhanced back wash (CEB) method, which is the subject of the present invention, and shows the addition of sodium hypochlorite. An example of the washing | cleaning method which performs backwashing is shown.

  In FIG. 6, 1 is raw water, 2 is a raw water tank, 3 is a main pump, 4 is a raw water supply valve, 5 is a membrane inlet pressure gauge, 6 is a water temperature gauge, 7 is a membrane module (or membrane filtration unit), and 8 is a membrane. Outlet pressure gauge, 9 is a flow sensor, 10 is a filtrate outlet valve, 11 is a filtrate tank inlet valve, 12 is a filtrate tank, 13 is treated water, 14 is a backwash pump, 15 is a backwash water supply valve, 16 Is a drain valve, 17 is a sodium hypochlorite tank, 18 is a sodium hypochlorite addition pump, and 19 is a sodium hypochlorite addition valve. In FIG. 6, the sodium hypochlorite addition amount control device is not shown.

  Next, a water treatment method and a cleaning method for the filtration membrane shown in FIG. 6 will be described. The raw water 1 flowing into the raw water tank 2 is supplied to the membrane module 7 by the main pump 3 via the raw water supply valve 4 and filtered (filtering step). Here, the filtration flow rate is performed by inverter-controlling the main pump 3 so that the value of the flow rate sensor 9 becomes constant. The filtered water flows into the filtrate water tank 12 through the flow rate sensor 9, the filtrate water outlet valve 10, and the filtrate water tank inlet valve 11. The filtered water exceeding the capacity in the filtered water tank 12 is passed to the next process as treated water 13. When filtration is performed for a predetermined time, backwashing is performed (backwashing step). In the backwashing process, the water in the filtrate water tank 12 (or the water in a backwash water tank (not shown) provided separately from the filtrate water tank) is supplied to the membrane module 7 by the backwash pump 14 via the backwash water supply valve 15. It is made by flowing from the secondary side to the primary side, and the water after backwashing is drained through the drain valve 16.

  After a predetermined number of times of the filtration step and the backwashing step are completed, the chemical is added to perform the backwashing (chemical addition backwashing step). In the case of FIG. 6, as sodium hypochlorite addition backwashing, sodium hypochlorite stored in the sodium hypochlorite tank 17 is replaced with sodium hypochlorite addition pump following the backwashing with the filtered water. 18 is added to the backwash water through a sodium hypochlorite addition valve 19 and water having a predetermined residual chlorine concentration is injected into the membrane module. When the inside of the membrane module 7 is filled with residual chlorine water of a predetermined concentration, the backwash pump 14 is temporarily stopped, each valve is closed, and the membrane module 7 is immersed in the residual chlorine water for a predetermined time (chemical solution immersion step). After immersing for a predetermined time, the backwash pump is started again, and backwashing is performed with filtered water, thereby rinsing off the chlorine water in the membrane module (rinsing step).

  As described above, a cleaning method for a filtration membrane including a backwashing step, a chemical addition backwashing step, a chemical solution immersion step, and a rinsing step is referred to as a chemical addition backwashing method. In addition to the above sodium hypochlorite, sulfuric acid, hydrochloric acid, and other chemicals may be used as cleaning chemicals for fouling substances on the membrane surface. Further, as disclosed in Patent Document 1, a plurality of chemicals may be used.

  By the way, as a flow control method of the backwash water in the normal backwashing process or the chemical addition backwashing process, for example, constant flow control is performed by PID control using an inverter. The conventional control method and apparatus will be described with reference to FIG. In FIG. 5, water in a backwash water tank 22 provided separately from the filtrate water tank is passed through a membrane filtration unit 21 via a backwash line 30 having a backwash pump 22, and a chemical solution is placed in the middle of the backwash line 30. An example in which an injection line 24 is provided is shown. In FIG. 5, 25 is a flow meter (transmitter), 26 is a flow controller (PID controller), 27 is an inverter, 28 is a controller (PLC), and 29 is a programmable operation display (POD).

  According to FIG. 5, flow control as described below is performed and flow monitoring is performed. The output of the flow meter 25 controls the pump motor in the feedback loop of the flow controller (PID controller) 26 → inverter 27 → backwash pump 23 motor. Further, the transmission output of the flow meter 25 is branched and directly input to the controller 28 to monitor whether or not an abnormal deviation has occurred with respect to the command flow rate. Further, a flow rate command value and setting parameters are transmitted from the control controller (normal PLC: programmable controller) 28 to the flow rate controller 26, and the flow rate controller 26 performs control according to this command value.

  Further, the current operation value and abnormality information are transmitted from the flow rate controller 26 to the control controller 28. The flow rate controller 26 monitors the vertical deviation with respect to the set flow rate. If the deviation is exceeded, an alarm is transmitted to the controller 28, and the controller 28 notifies the deviation abnormality. Furthermore, the frequency range assumed in each set flow rate is set, and when the frequency range is out of the frequency range, the controller 28 has a function of transmitting an alarm (frequency monitoring function).

Although the above description relates to a chemical treatment backwash type water treatment apparatus, a chemical liquid injection apparatus for a water treatment apparatus targeted by the present invention described later is not limited to the above apparatus. For example, in FIG. 6, sodium hypochlorite stored in the sodium hypochlorite tank 17 is converted into backwash water via a sodium hypochlorite addition valve 19 using a sodium hypochlorite addition pump 18. A chemical solution injection device that sterilizes raw water by providing a chemical solution injection line to be added to the raw water supply line between the water temperature gauge 6 and the membrane module 7 and injecting the chemical solution into the raw water is also an object. In this case, there is a case where chemical addition backwashing is not performed and only raw water sterilization is used, and a case where chemical addition backwashing is used in combination, and in a small scale system, a normal backwashing process may not be performed.
JP 2004-41935 A

  By the way, the conventional chemical solution injection apparatus in the water treatment apparatus for sterilizing raw water or the chemical addition backwash (CEB) type water treatment apparatus as described above has the following problems.

  The chemical injection pipe prevents the chemical liquid from leaking by an on-off valve (usually an automatic on-off valve) that divides the chemical liquid line, but there is a problem that the chemical liquid remains in the injection nozzle portion. As a result, when water is not flowing into the main pipe through which raw water or backwash water flows, the chemical solution remaining in the chemical injection pipe flows into the main pipe and comes into contact with the pipe, which is a cause of corrosion of the pipe. It was. Further, it is desirable that the chemical solution injection tube is made of a corrosion-resistant plastic tube. However, from the viewpoint of strength, it is desirable to use a lining pipe. In this case, there is a problem that the lining is peeled off and the injection pipe is corroded.

  The present invention has been made in view of the above points, and an object of the present invention is to suppress the remaining of the chemical liquid in the chemical injection pipe in the chemical injection apparatus for the water treatment apparatus, and to connect the chemical injection pipe and the main pipe. It is to prevent corrosion accidents.

  In order to solve the above-described problems, the present invention is a chemical liquid injection device for water treatment that purifies raw water with a filtration membrane to obtain treated water, and is a reverse for washing raw water or a filtration membrane in the water treatment. In a chemical injection device for a water treatment apparatus, in which a chemical injection pipe is inserted through an opening / closing valve into a chemical injection port provided in a main pipe through which washing water flows, the upstream side of the port portion of the main pipe And cleaning means in the chemical injection pipe formed by connecting a water introduction pipe through a joint between the chemical injection pipe and the downstream side of the on-off valve (claim 1). With the above configuration, based on the pressure difference between the upstream side and the downstream side, water flows from the main pipe side to the chemical injection pipe side in the water introduction pipe, and the inside of the chemical injection pipe is washed with the flowing water of the main pipe. As a result, the remaining chemical is suppressed. Thereby, the corrosion accident of piping can be prevented.

  As an embodiment of the invention of claim 1, the inventions of claims 2 to 5 are preferable. That is, in the chemical injection device according to the first aspect, a portion for providing the port of the main pipe is provided with a contraction portion for reducing the pressure of the water flowing through the main pipe (claim 2). Thereby, the flow of water to the chemical injection pipe side in the water introduction pipe is promoted based on the decompression of the contraction portion, and the cleaning effect is improved.

  Furthermore, from the viewpoint of preventing corrosion of the chemical injection pipe itself, the chemical injection apparatus according to claim 1 or 2, wherein at least a material of a joint provided in the chemical injection pipe and the chemical injection pipe is corrosion resistant to the chemical. Material (Claim 3).

  Further, from the viewpoint of using the dynamic pressure of the main pipe flowing water for improving the cleaning effect, in the chemical liquid injector according to claim 1, the joint provided in the main pipe is inserted into the water flowing portion of the main pipe. In addition, a dynamic pressure receiving portion that receives the dynamic pressure of the flowing water and promotes the flow of water to the chemical injection pipe side in the water introduction pipe is provided (Claim 4). Furthermore, from the viewpoint of simplifying the structure, in the chemical injection device according to claim 4, the dynamic pressure receiving portion cuts an end portion of a pipe inserted into a water flow portion of the main pipe of the joint obliquely. The inclined opening portion is disposed toward the upstream side of the flowing water (claim 5).

  The above-mentioned problems can also be solved by the inventions of claims 6 to 7 below. That is, in the chemical injection device according to claim 1, the cleaning means in the chemical injection pipe is a self-cleaning means using a pressure difference at the peripheral portion of the chemical injection pipe, instead of the one described in claim 1. In this self-cleaning means, the chemical injection pipe is inserted into the flanged port provided in the main pipe with a gap in a liquid-tight manner, and the chemical injection pipe is inserted into the water flow portion of the main pipe. It is assumed that the front end of the chemical is disposed obliquely through the inclined opening toward the downstream side of the flowing water, and further, a hole is provided in the outer peripheral portion of the chemical injection pipe facing the gap in the flanged port. The main pipe has a structure in which the flowing water flows out of the inclined opening via the gap in the flanged port and the hole of the chemical injection pipe (Claim 6).

  Furthermore, in the chemical injection device according to claim 6, the self-cleaning means is configured to insert a chemical injection pipe in a liquid-tight manner through a sleeve into a flanged port provided in the main pipe, The inner peripheral portion of the sleeve is provided with an introduction groove for introducing backwash water along the axial direction of the chemical injection pipe and a communication groove to the hole. It is assumed that a structure is provided that flows out of the inclined opening via a communication groove and a hole of the chemical injection pipe (Claim 7).

  Moreover, as invention of the chemical | medical solution injection | pouring apparatus for water treatment apparatuses of a chemical addition backwash system, the filtration membrane which purifies raw water and obtains treated water, and a part of the treated water serves as backwash water for the filtration membrane In a chemical injection device for a water treatment device of a chemical addition backwashing system comprising a backwashing line for backwashing a filtration membrane and a chemical injection line for adding a chemical to the backwashing line for backwashing The chemical injection line is formed by inserting a chemical injection pipe into a chemical injection port provided in the backwash line via an on-off valve, and provided with cleaning means in the chemical injection pipe. The means is characterized in that the upstream side of the port portion of the backwash line and the downstream side of the on-off valve of the chemical injection pipe are connected by a water introduction pipe via a joint. 8).

  According to this invention, in the chemical injection device for the water treatment device, the chemical solution remaining in the chemical injection piping can be suppressed, and corrosion accidents of the chemical injection piping and the main piping can be prevented.

  An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 will be described with respect to a chemical injection device for a chemical treatment backwashing water treatment apparatus, but the present invention is not limited to this embodiment.

  1 is a schematic configuration diagram according to an embodiment of the chemical liquid injector of the present invention, FIG. 2 is a schematic configuration diagram according to a different embodiment of the joint (main pipe side) in FIG. 1, and FIG. FIG. 4 is a schematic configuration diagram according to an embodiment different from FIG. 3. In each said figure, the same number is attached | subjected and shown to the member with the same function.

In FIG. 1, 24 is a chemical liquid injection line, 24a is a chemical liquid injection pipe, 30 is a backwash line as a main pipe, 30a is a port for chemical injection, 30b is a flow reducing portion, 41 is an on-off valve, 42 is a throttle valve, 50 is a joint (backwash line side), 51 is a joint (chemical solution injection pipe side), and 52 is a water introduction pipe. According to the above configuration, the backwash water in the backwash line 30 (the flow is indicated by G) has a higher pressure P ₁ on the upstream side than the pressure P ₂ on the downstream side. As indicated by F, the water also branches and flows into the chemical liquid injection pipe 24a via the water introduction pipe 52. Therefore, when the on-off valve 41 is closed after the addition of the chemical, the chemical remaining in the chemical liquid injection pipe 24a is washed away by this branch flow. Therefore, a pipe corrosion accident in the backwash line can be prevented.

The material of the joint 51 provided in the chemical injection pipe 24a and the chemical injection pipe is preferably a corrosion-resistant material against chemicals from the viewpoint of preventing corrosion of the chemical injection pipe itself. Incidentally, the contraction portion 30b is not necessarily required, to increase the pressure difference between the pressure P ₂ of the pressure P ₁ and the downstream side of the upstream side, in order to improve the chemical cleaning effect by the branch stream, for example, In addition, it is preferable that a part of the backwash line is made into a venturi shape to provide a contracted portion.

Next, FIG. 2 will be described. 2A shows an embodiment in which the joint (backwash line side) 50 in FIG. 1 has a joint configuration as indicated by 50a. This joint 50a is inserted into the backwash water flow portion of the backwash line 30, receives the dynamic pressure of backwash water (P _{V in the} figure), and supplies water to the chemical injection pipe side in the water introduction pipe 52. It is intended to promote the flow of

FIG. 2 (b) shows an embodiment of a joint 50b different from FIG. 2 (a). The joint 50b in FIG. 2 (b) is provided with an inclined opening portion formed by obliquely cutting the tip of a pipe inserted in the backwash water flow portion of the backwash line facing the upstream side of the backwash water. in, the P _V Gado pressure receiving portion shown. The structure of the joint shown in FIG. 2B is simpler than that shown in FIG.

  Next, the embodiment of FIG. 3 will be described. 3, 24 is a chemical injection line, 24a is a chemical injection pipe, 24b is an inclined opening, 24c and 32 are flanges, 30 is a backwash line, 31 is a port with a flange, 60 is a hole provided in the chemical injection pipe, Reference numeral 71 denotes a gap between the flanged port and the chemical solution injection pipe, and reference numeral 75 denotes a seal.

  The embodiment of FIG. 3 is an embodiment provided with a self-cleaning means using the pressure difference at the peripheral portion of the chemical injection pipe, and this self-cleaning means is a flanged port 31 provided with a chemical injection pipe 24a in the backwash line 30. An inclined opening 24b is formed on the downstream side of the backwash water by providing a gap 71 therein and liquid-tightly inserting it, and obliquely cutting the tip of the chemical injection pipe 24a inserted in the backwash water flow-through portion. The backwash water is further provided with a hole 60 in the outer peripheral portion of the chemical injection pipe so as to face the gap 71 in the flanged port, so that the backwash water is provided in the gap in the flanged port 31. 71 and the hole 60 of the chemical injection pipe are configured to flow out from the inclined opening 24b.

The pressure P ₂ on the downstream side of the inclined opening 24b is lower than the pressure P ₁ shown in the vicinity of the gap 71 in the backwash line 30 (negative pressure). Self-cleaning using the difference becomes possible. The inclination angle of the inclined opening 24b is, for example, 30 to 45 °. One to four holes 60 of the chemical injection pipe are provided on the outer periphery of the upper part of the chemical injection pipe.

  In FIG. 1 and FIG. 3, the chemical solution input position in the water flow portion to which the chemical solution is added, which is the tip portion of the chemical injection pipe 24a, is arranged near the central portion with respect to the water flow portion in the pipe through which water flows. However, the position is not particularly limited as long as the charged chemical solution is appropriately mixed in water.

  Next, the embodiment of FIG. 4 will be described. 4A is a side cross-sectional view of a main part according to the embodiment, and FIG. 4B is a side cross-sectional view along the line AA in FIG. 4A.

  The embodiment of FIG. 4 is an embodiment in which the sleeve 70 is provided based on the embodiment of FIG. 3, and the sleeve 70 shows insufficient strength when the chemical injection pipe 24a is made of a corrosion-resistant material, for example, a resin material such as PVC. The basic principle of the self-cleaning is the same as that of the embodiment of FIG.

  In the self-cleaning means in the embodiment of FIG. 4, the chemical injection pipe 24a is liquid-tightly inserted through the sleeve 70 into the flanged port 31 provided in the backwash line, and the inner periphery of the sleeve 70 is inserted. Is provided with, for example, two introduction grooves 72 for introducing backwash water along the axial direction of the chemical injection pipe, and a communication groove 73 to a hole provided near the hole of the chemical injection pipe. Based on the negative pressure of the portion 24b, backwash water flows out of the inclined opening 24b through the introduction groove 72, the communication groove 73 and the hole 60 of the chemical injection pipe as shown in FIG. Yes.

  The material of the sleeve 70 may be a resin material when the thickness is sufficient and there is no problem in strength maintenance. However, when the thickness is small and the strength is important, iron or stainless steel with a corrosion-resistant coating is used. . Further, the flanged port 31 is provided with ribs 33 as required for strength.

The typical block diagram which concerns on the Example of the chemical | medical solution injection device of this invention. The typical block diagram which concerns on the Example from which the coupling (main piping side) in FIG. 1 differs. The typical block diagram which concerns on the Example different from FIG. 1 of the chemical injection device of this invention. The typical block diagram which concerns on the Example different from FIG. 3 of the chemical | medical solution injection device of this invention. The system diagram of the conventional control method and apparatus which perform PID control of the flow volume of backwash water with the inverter for backwash pumps. Schematic system diagram of an example of a general filtration membrane cleaning method by a conventional chemical addition backwashing system.

Explanation of symbols

  24: Chemical liquid injection line, 24a: Chemical liquid injection pipe, 24b: Inclined opening, 24c, 32: Flange, 30: Backwash line, 30a: Port, 30b: Constricted part, 31: Port with flange, 33: Rib, 41: Open / close valve, 42: Throttle valve, 50, 50a, 50b: Fitting (backwash line side), 51: Fitting (chemical solution injection pipe side), 52: Water introduction pipe, 60: Hole, 70: Sleeve, 71: Gap, 72: introduction groove, 73: communication groove, 75: seal.

Claims (8)

A chemical injection device for water treatment that purifies raw water with a filtration membrane to obtain treated water, and is provided in a main pipe through which the raw water in the water treatment or backwash water for washing the filtration membrane flows In the chemical injection device for the water treatment device, in which the chemical injection pipe is inserted into the injection port via the on-off valve,
A cleaning means in the chemical injection pipe is provided in which the upstream side of the port portion of the main pipe and the downstream side of the on-off valve of the chemical injection pipe are connected via a joint by a water introduction pipe. A chemical solution injection device for a water treatment device. 2. The chemical injection device for water treatment apparatus according to claim 1, wherein a contraction portion for reducing the pressure of the water flowing through the main pipe is provided in a portion where the port of the main pipe is provided. 3. apparatus. The chemical solution injection apparatus according to claim 1 or 2, wherein at least the chemical injection pipe and a joint material provided in the chemical injection pipe are made of a corrosion-resistant material against the chemical. Injection device. 2. The chemical injection device according to claim 1, wherein the joint provided in the main pipe is inserted into a water flow portion of the main pipe and receives the dynamic pressure of the flow water to the chemical injection pipe side in the water introduction pipe. A chemical injection device for a water treatment apparatus, comprising a dynamic pressure receiving portion that promotes the flow of water. The chemical injection device according to claim 4, wherein the dynamic pressure receiving portion is arranged on the upstream side of the flowing water through an inclined opening portion that is obliquely cut at a tip portion of a pipe inserted into a water flow portion of the main pipe of the joint. A chemical liquid injection device for a water treatment device, characterized in that the chemical solution injection device is directed toward the water treatment device. The chemical injection device according to claim 1, wherein the cleaning means in the chemical injection pipe is a self-cleaning means using a pressure difference in the peripheral portion of the chemical injection pipe, instead of the one in the first aspect. The cleaning means inserts the chemical injection pipe into the flanged port provided in the main pipe in a liquid-tight manner, and the tip of the chemical injection pipe inserted into the water flow portion of the main pipe An inclined opening that is cut obliquely is arranged toward the downstream side of the flowing water, and further, a hole is provided in the outer peripheral portion of the chemical injection pipe so as to face the gap in the flanged port. The chemical liquid injection device for a water treatment device is provided with a configuration in which the flow-through water flows out from the inclined opening through a gap in the flanged port and a hole in the chemical injection pipe. The chemical injection device according to claim 6, wherein the self-cleaning means is configured to insert a chemical injection pipe into a flanged port provided in the main pipe in a liquid-tight manner via a sleeve. The inner peripheral portion is provided with an introduction groove for introducing backwash water along the axial direction of the chemical injection pipe and a communication groove to the hole, and the flow water of the main pipe is connected to the introduction groove and the communication groove. A chemical solution injection device for a water treatment device, characterized in that the chemical solution injection device is configured to flow out from the inclined opening through a hole of the chemical injection pipe. A filtration membrane for purifying raw water to obtain treated water, a backwash line for backwashing the filtration membrane using a part of the treated water as backwash water for the filtration membrane, and chemicals in this backwash line In the chemical injection device for the water treatment device of the chemical addition backwashing method equipped with the chemical injection line for adding and backwashing,
The chemical injection line is formed by inserting a chemical injection pipe into a chemical injection port provided in the backwash line via an on-off valve, and includes a cleaning means in the chemical injection pipe. For the water treatment device, wherein the upstream side of the port part of the backwash line and the downstream side of the on-off valve of the chemical injection pipe are connected via a joint by a water introduction pipe. Chemical injection device.

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