JP6026105B2 - Purified water production equipment - Google Patents

Description

  The present invention relates to a purified water production apparatus for treating raw water using a filtration membrane device having a reverse osmosis membrane or a nanofiltration membrane.

  In production equipment that produces purified water by treating relatively clean water such as industrial water, tap water, and well water, devices that treat these waters using reverse osmosis membranes or nanofiltration membranes are conventionally known. (For example, refer to Patent Document 1).

  In such a reverse osmosis membrane and nanofiltration membrane filtration, the permeated amount of filtrate varies greatly depending on the temperature of the raw water. For example, if the supply pressure of raw water to a reverse osmosis membrane and a nanofiltration membrane (hereinafter referred to as a filtration membrane) is constant, the amount of filtrate at a raw water temperature of 25 ° C. will be 100, but depending on the characteristics of the filtration membrane, 10 At 35 ° C., it decreases to approximately 65, and at 35 ° C., it becomes 128, and at 10 ° C. and 35 ° C., the difference in the amount of filtered water is about twice.

  In addition, the amount of filtered water may decrease due to the clogging of the filtration membrane. Therefore, in order to stably operate this type of membrane filtration device, it is necessary to secure a constant amount of filtered water throughout the year and to maintain a constant recovery rate (filtered water amount / raw water amount × 100%).

JP 2006-281023 A

  In order to maintain the filtered water volume and the recovery rate, there is a method of heating the raw water to keep the raw water temperature constant and the permeated water quantity constant, but in this case, the equipment for heating the raw water and large energy are required. I need.

In particular, this type of filtration membrane device requires a certain amount of concentrated drainage, and the energy used for heating the concentrated drainage is discarded without being effectively used. Further, in this method of heating raw water, there is a problem that it is impossible to eliminate the decrease in the amount of permeated water due to the clogging of the filtration membrane.
Therefore, there is a method of controlling the discharge amount and pressure of the filtered water supply pump in order to make the supply water amount and the supply water pressure constant.

Specifically, there are a method for controlling the number of revolutions of the raw water supply pump and a method for controlling the discharge amount by providing a control valve on the outlet side of the raw water supply pump.
However, even if the amount of water supplied to the filtration membrane and the supply water pressure are made constant, this method alone cannot make the amount of filtered water and the recovery rate constant. This is because, in order to make the amount of filtered water and the recovery rate constant, the amount of concentrated water must also be made constant at the same time.

  In order to make the concentrated water amount constant, a method for controlling the flow rate in the concentrated water line, for example, a method of providing a control valve and a flow rate transmitter to make the concentrated water amount constant is conceivable. Becomes an expensive device.

  The present invention has been made in consideration of the problems in the conventional purified water production apparatus as described above, and is not affected by the temperature fluctuation of the raw water, and can maintain a constant filtered water amount and a constant recovery rate. A water production apparatus is provided.

  In the present invention, the amount of water supplied to the filtration membrane is made constant, and the amount of concentrated water generated during filtration is made constant by a simple configuration, so that the amount of filtered water and the recovery rate are kept constant without being affected by temperature fluctuations of the raw water. Has led to the realization of an apparatus for producing purified water that can be made.

The first aspect of the present invention is an apparatus for producing purified water by treating raw water with a filtration membrane device,
A raw water supply pump provided in a raw water supply line leading to the filtration membrane device;
Filtration having a flow rate transmitter provided in the filtrate water line of the filtration membrane device, controlling the number of revolutions of the raw water supply pump based on a flow rate signal transmitted from the flow rate transmitter, and maintaining a constant filtrate water flow rate Water flow control means;
A concentrated water constant flow valve that is provided in the concentrated water line of the filtration membrane device and makes the flow rate of the concentrated water constant;
A pressure reducing valve interposed between the filtration membrane device and the concentrated water constant flow valve to reduce the concentrated water pressure;
The gist of the invention is that it includes a pressure indicator interposed between the pressure reducing valve and the concentrated water constant flow valve.

The second embodiment of the present invention further includes a concentrated water return line that branches from between the pressure indicator and the concentrated water constant flow valve and returns the concentrated water to the raw water supply line.
The gist of the invention is that the concentrated water return line is provided with a second concentrated water constant flow valve for keeping the concentrated water flow rate constant.

  As the filtration membrane device in the present invention, it is preferable to use a reverse osmosis membrane or a nanofiltration membrane, and the filtered water filtered by the reverse osmosis membrane is used for medical water, for example, and filtered water filtered by the nanofiltration membrane. Is used, for example, in dehardening and desilicaizing water.

  As the concentrated water constant flow valve in the present invention, a constant flow valve configured to supply a constant flow rate even when the water pressure fluctuates on the primary side (inflow side) or the secondary side (outflow side) is used. . The principle of operation is that a fluid pressure is received by a piston (movable valve) in the valve body, and the fluid passage area in the valve body is changed in balance with the spring force to obtain a constant flow rate.

  This type of constant flow valve is usually used to prevent an excessive flow rate from flowing in one place, but in the present invention, it is used to keep the flow rate of the concentrated water line constant.

  In addition, since the constant flow valve does not require a control device for pressure fluctuation, there is an advantage that space saving and cost saving can be achieved, but there is a limitation in the operating differential pressure range. Therefore, in the present invention, a pressure reducing valve is provided on the upstream side of the constant flow valve so as to reduce the concentrated water pressure so that the pressure of the concentrated water is within the operating differential pressure range of the constant flow valve.

  According to the purified water production apparatus of the present invention, a constant amount of filtered water and a constant recovery rate can be maintained throughout the year without being affected by the raw water temperature.

It is a block diagram which shows 1st embodiment of the purified water manufacturing apparatus which concerns on this invention. It is a block diagram which shows 2nd embodiment of the purified water manufacturing apparatus which concerns on this invention.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

FIG. 1 shows a basic configuration of a purified water production apparatus according to the present invention as a first embodiment.
In the figure, the purified water production apparatus A is provided with a variable capacity type raw water supply pump 1 and a filtration membrane device 2 in the raw water supply line L1, and a filtrate flow rate transmitter 3 in the filtrate water line L2 from the filtration membrane device 2. Is provided.

  Moreover, it has the filtrate flow rate regulator 4 and the raw | natural water pump inverter 5 which act | operate in response to the flow signal from the filtrate water flow transmitter 3, and depressurize the pressure of concentrated water to the concentrated water line L3 from the filtration membrane apparatus 2. A pressure reducing valve 6, a concentrated water constant flow valve 7, and a pressure indicator 8 for displaying the pressure on the inlet side of the concentrated water constant flow valve 7 are provided.

Based on the flow rate signal measured by the filtration membrane flow rate transmitter 3, the filtered water flow rate regulator 4 measures the amount of water, transmits the necessary signal to the raw water pump inverter 5, and changes the rotational speed of the raw water supply pump 1. Thus, the amount of water supplied to the filtration membrane device 2 is controlled.
The filtration membrane flow rate transmitter 3, the filtrate flow rate regulator 4 and the raw water pump inverter 5 function as a filtrate flow rate control means for keeping the filtrate flow rate constant.

Thereby, about filtered water, it can be made constant within the discharge capacity range of the raw | natural water supply pump 1 irrespective of the temperature of raw | natural water, and obstruction | occlusion of the filtration membrane in the filtration membrane apparatus 2. FIG.
On the other hand, the amount of concentrated water is kept constant by providing the concentrated water constant flow valve 7.

  However, a commercially available constant flow valve has a limit in the allowable differential pressure range of the constant flow valve. For example, the FPC series manufactured by Tokyo Keiso Co., Ltd. has a pressure of 0.05 to 0.7 MPa, and the NSPW series has a pressure of 0.03 to 1.0 MPa.

  The raw water supply pressure in the purified water production apparatus using reverse osmosis membranes or nanofiltration membranes often exceeds 1 MPa when the raw water is cold, and the concentrated water pressure is only about 0.1 MPa lower than the raw water supply pressure. If the concentrated water is supplied to the constant flow valve with the pressure as it is, it will be out of the differential pressure range.

  In order to solve this, in the present embodiment, a pressure reducing valve 6 for reducing the concentrated water pressure is disposed in the concentrated water line L3 upstream of the concentrated water constant flow valve 7. As the pressure reducing valve 6, it is desirable to select a valve capable of adjusting the pressure to be reduced to some extent, such as a globe valve, a needle valve, and a butterfly valve. Although the pressure reducing valve 6 can be replaced by a pressure reducing device such as an orifice, it is desirable to use the above-mentioned valves in consideration of ease of adjustment.

Moreover, in order to visually check the pressure of the concentrated water line L3 on the inlet side of the concentrated water constant flow valve 7, a pressure indicator 8 is installed.
Usually, since the concentrated water drainage is discharged as non-pressure drainage, the pressure indicated by the pressure indicator 8 in the concentrated water line L3 on the inlet side of the concentrated water constant flow valve 7 is the case where the concentrated water constant flow valve 7 is provided. The pressure difference is almost the same.

Therefore, the pressure reducing valve 6 for depressurizing the concentrated water is adjusted, and the differential pressure of the concentrated water constant flow valve 7 is set.
At this time, if the differential pressure is set in consideration of the temperature fluctuations of the raw water and the operating range of the concentrated water constant flow valve 7, a constant amount of filtered water and a recovery rate can be maintained regardless of the temperature of the raw water and the filtration membrane blockage. It is possible to realize a purified water production apparatus capable of

FIG. 2 shows a second embodiment of the purified water production apparatus according to the present invention.
2 that are the same as those in FIG. 1 are assigned the same reference numerals and descriptions thereof are omitted.

In the purified water production apparatus B shown in the figure, the branch line L4 is branched from the concentrated water line L3 between the pressure reducing valve 6 and the concentrated water constant flow valve 7, and is connected to the raw water supply line L1 upstream of the raw water supply pump 1. doing. Thereby, a part of concentrated water is circulated.
The branch line L4 is provided with a second concentrated water constant flow valve 9 so that a constant filtered water amount and a recovery rate can be maintained even when the concentrated water is circulated.

  In this configuration, the differential pressure is set in consideration of the temperature fluctuation of the raw water and the operating range of the concentrated water constant flow valve 7 and the second concentrated water constant flow valve 9, thereby being influenced by the temperature of the raw water and the membrane clogging. In addition, it is possible to provide a purified water production apparatus that can maintain a constant amount of filtered water and a recovery rate.

A demonstration test of the purified water production apparatus of the present invention was performed with the configuration shown in FIG.
Raw water supply pump 1: GRUNDFOS CR1-19
Filtration membrane device 2: Toyobo Co., Ltd. HA5230
Filtrated water flow transmitter 3: Tohflo Corporation HF-GCC30
Filtration water flow regulator 4: OMRON Corporation E5CN
Raw water pump inverter 5: Mitsubishi Electric Corporation FR-D720
Pressure reducing valve 6: Needle valve concentrated water constant flow valve 7: Tokyo Instrumentation FPC 7.0 L / min
(Differential pressure range 0.05 to 0.7 MPa)
Pressure indicator 8: Blouson tube type pressure indicator In the test, the raw water temperature was varied and the measurement was performed.

The measurement items were raw water temperature, filtration membrane supply pressure, filtered water volume, concentrated water volume, and constant flow valve (concentrated water constant flow valve) inlet pressure.
The recovery rate is a calculated value (filtered water amount / (filtered water amount + concentrated water amount) × 100%).
The amount of concentrated water was collected in a container and measured.

The test results are shown in Table 1.
As shown in Table 1, in the raw water temperature range of 10 ° C to 30 ° C, the inlet pressure of the concentrated water constant flow valve is within the differential pressure range (0.05 to 0.7 MPa), and manual adjustment is required. It was confirmed that the purified water production apparatus could be operated without

DESCRIPTION OF SYMBOLS 1 Raw water supply pump 2 Filtration membrane apparatus 3 Filtrated water flow transmitter 4 Filtrated water flow regulator 5 Raw water pump inverter 6 Pressure reducing valve 7 Concentrated water constant flow valve 8 Pressure indicator 9 Second concentrated water constant flow valve L1 Raw water supply line L2 Filtration water line L3 Concentrated water line L4 Branch line

Claims (2)

In an apparatus for producing purified water by processing raw water with a filtration membrane device,
A raw water supply pump provided in a raw water supply line leading to the filtration membrane device;
Filtration having a flow rate transmitter provided in the filtrate water line of the filtration membrane device, controlling the number of revolutions of the raw water supply pump based on a flow rate signal transmitted from the flow rate transmitter, and maintaining a constant filtrate water flow rate Water flow control means;
A concentrated water constant flow valve that is provided in the concentrated water line of the filtration membrane device and makes the flow rate of the concentrated water constant;
Is interposed between the filtration membrane apparatus and the concentrated water constant flow valve, e Bei a pressure reducing valve for reducing the concentrated water pressure,
Branching from between the pressure reducing valve and the concentrated water constant flow valve, further having a concentrated water return line for returning the concentrated water to the raw water supply line;
A purified water production apparatus , wherein the concentrated water return line is provided with a second concentrated water constant flow valve for keeping a concentrated water flow rate constant . The purified water production apparatus according to claim 1 , wherein the filtration membrane device has a reverse osmosis membrane or a nanofiltration membrane.

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