JPH06210140A - Membrane separator - Google Patents

Abstract

PURPOSE:To make a two-stage reverse-osmosis membrane device compact and to reduce the running cost. CONSTITUTION:The rotating shafts of the high-pressure pump 12, motor 14, energy recovery turbine 16 and low-pressure pump 18 are connected. Concd. water 26 of a high-pressure reverse-osmosis membrane unit 24 is sent to the turbine 16 to recover driving energy, and the permeated water 28 of the unit 24 is pressurized by the low-pressure pump 18 and sent to a low-pressure reverse-osmosis membrane unit 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation device using a reverse osmosis membrane used for desalting and the like, and more specifically to a membrane separation device for collecting driving energy during operation and reducing running cost. .

[0002]

2. Description of the Related Art In a desalination apparatus using a reverse osmosis membrane,
Conventionally, it has been general to use one type of reverse osmosis membrane to obtain permeated water by one-step desalting operation. Further, in the case where the permeated water is required to have a high purity, an ion exchange device has been provided in the subsequent stage of the desalting device to perform further treatment. The reason why such a treatment method is adopted is that the reverse osmosis membrane is expensive, and the amount of water and the quality of water obtained with respect to the operating pressure at the inlet are higher in running cost than the ion exchange resin method. That was the main reason.

Recently, however, technological development of reverse osmosis membranes has advanced, and it has become possible to use high-performance reverse osmosis membranes at low cost. As a result, so-called 2 types of membranes having different desalination performances are used. A stage treatment method is being adopted. For example, in FIG.
As shown in Fig. 1, the reverse osmosis membrane unit 1 with a high desalination rate in the first stage
The reverse osmosis membrane unit 2 with a low desalination rate was installed in the second stage 2
In the case of the stage treatment method, a single raw water supply pump 3 provided on the inlet side of the first-stage reverse osmosis membrane unit often applies a necessary pressure to both the first-stage unit and the second-stage unit. . However, when the raw water has a high salt concentration like seawater and therefore it is necessary to apply high pressure for desalination, the required supply pressures for the first and second stages are the upper pressure resistance of the first reverse osmosis membrane. In some cases, the flow configuration shown in FIG. 3 cannot be used.

Therefore, the flow structure shown in FIG. 4 is required. In this case, however, the primary permeated water tank 4, the second stage reverse osmosis membrane unit water supply pump 5 and the pump 5 are further provided.
Since an electric motor (not shown) attached to the device becomes necessary, the device becomes complicated, and various problems occur such as an increase in the installation area of the device and an increase in pump driving energy.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to reduce the installation area of the device and to require a second-stage feed pump electric motor. Another object of the present invention is to provide a membrane separation device by the reverse osmosis membrane method in which the operating cost of the device is reduced by further collecting the driving energy.

[0006]

In order to achieve the above object, the present invention provides a high-pressure pump for pressurizing raw water to supply it to a high-pressure reverse osmosis membrane unit, an electric motor for supplying drive power to the high-pressure pump, and A low-pressure pump that pressurizes the permeated water of the high-pressure reverse osmosis membrane unit and supplies it to the low-pressure reverse osmosis membrane unit,
And a high-pressure reverse osmosis membrane unit and a low-pressure reverse osmosis membrane unit, and a power unit configured by connecting an energy recovery turbine driven by concentrated water sent from the high-pressure reverse osmosis membrane unit to one of these rotating shafts. The high-pressure reverse osmosis membrane unit and the low-pressure reverse osmosis membrane unit sequentially reverse osmosis the raw water supplied to the high-pressure pump to take out permeated water and concentrated water from the low-pressure reverse osmosis membrane unit, and also an energy recovery turbine. Thus, the membrane separation device is configured to recover the driving energy of the pump from the concentrated water of the high-pressure reverse osmosis membrane unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a base on which a high pressure pump 12, an electric motor 14, and an energy recovery turbine 1 are mounted.
6, low pressure pump 18 in this order from the left side of the drawing, and
These rotary shafts are connected and arranged so as to form a single shaft, and the pump 12, the electric motor 14, the turbine 16, and the pump 18 constitute a power unit 20. Reference numeral 22 is the electric motor 14 and the energy recovery turbine 1.
A one-way (one-way) clutch that connects the rotating shafts of 6 is connected when the number of rotations of the recovery turbine 16 reaches a predetermined value. By driving the electric motor 14, the high-pressure pump operates, and the raw water 23 containing impurities such as salts to be removed is supplied to the high-pressure reverse osmosis membrane unit (first-stage reverse osmosis membrane unit) 24 in a high pressure state. And subjected to reverse osmosis. The high-pressure concentrated water 26 (first-stage concentrated water) flowing out from the high-pressure reverse osmosis membrane unit 24 is sent to the energy recovery turbine 16 and thereby the turbine 16
Is driven and recovered as drive energy for the low-pressure pump 18 and as a part of drive energy for the high-pressure pump 12. The concentrated water 26 from which energy has been recovered by the recovery turbine is then discarded outside the system. On the other hand, the permeated water 28 (first-stage permeated water) of the high-pressure reverse osmosis membrane unit 24 is not returned to the atmospheric pressure and is directly supplied to the low-pressure pump 1.
After being sent to 8 to be pressurized to a relatively low pressure, it is sent to a low-pressure reverse osmosis membrane unit (second-stage reverse osmosis membrane unit) 30 and further subjected to reverse osmosis treatment. As a result, the relatively low-pressure second-stage concentrated water 32 and the salt-removed second-stage permeated water 34 are extracted from the unit 30. The second-stage concentrated water 32 is usually recovered and used as water to be treated in the high-pressure reverse osmosis membrane unit.

Incidentally, in the case of desalination of seawater, high pressure porosity is generally used.
Pump pressure is 60 to 30 kg / cm ², Low pressure pump pressure
Power is 10-30kg / cm²I hope it is about
Yes.

In the case of the above embodiment, the primary power source of the power transmission system is the electric motor 14, and the output powers the high-pressure pump 12 to convert it into water horsepower. Normally, about 35% of this water horsepower is consumed to obtain permeate from the high-pressure reverse osmosis membrane unit 24, and the remaining about 65% water horsepower is guided to the energy recovery turbine 16 as the first-stage concentrated water, Here the energy is recovered as turbine output. The turbine power recovered is typically about 30% of the power provided to the motor 14. The turbine output thus recovered is consumed to drive the low-pressure pump 18, but normally, even if the low-pressure pump 18 is driven, the output is still excessive. Therefore, the surplus turbine output is further consumed by the one-way clutch 2
2 is used to reduce the output of the electric motor 14 to achieve comprehensive energy recovery.

That is, in the arrangement of the above embodiment, the recovered power is preferentially used to drive the low-pressure pump 18, and the remaining recovered power is used to reduce the output of the electric motor 14. It is possible. Furthermore, since the transmission of shaft torque between each device is most rational, the shaft strength can be designed according to the required torque for each device, and each device does not require special specifications. The advantage is that standard products can be used as they are.

It should be noted that the arrangement of the power parts other than the present embodiment (for example, the arrangement of the power parts as in the second embodiment to be described later) may be used, but in this case, as described later, the axial torque to be transmitted is different between the devices. Since they overlap each other, greater axial strength is required than in the case of this embodiment, and it becomes difficult to apply the standard product.

FIG. 2 shows another embodiment of the present invention.
In this example, the arrangement order of the power units 20 is different. That is, the energy recovery turbine 16, the one-way clutch 22, the electric motor 14, the high-pressure pump 12,
The low-pressure pump 18 is arranged in this order. Since other configurations are the same as those of the above-mentioned embodiment, the same reference numerals are given to the same portions and the description thereof will be omitted.

In the case of this example, since the power is transmitted to the low pressure pump 18 through the rotary shaft of the high pressure pump 12,
A larger load is applied to the rotary shaft of the high-pressure pump 12 than in the case of the first embodiment. Therefore, as the rotary shaft of the high-pressure pump 12,
Although there is a drawback that a rotating shaft having a higher strength is required than in the case of the above-mentioned embodiment, there is no problem in energy recovery.

[0015]

According to the present invention, the high-pressure first-stage concentrated water is supplied to the energy recovery turbine to be recovered as a part of the pump driving energy, so that the operating cost is reduced. Moreover, since the first-stage permeated water is pressurized by the low-pressure pump and sent to the low-pressure reverse osmosis membrane unit, the pressure applied to the high-pressure reverse osmosis membrane unit may be lower than that in the conventional system shown in FIG. Therefore, desalination treatment of raw water containing high-concentration salt is possible with one electric motor, and the installation area is smaller than that of the conventional method.

Further, according to the present invention, there is an advantage that the primary permeated water tank and the electric motor for the low pressure pump are unnecessary.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the present invention.

FIG. 2 is a flowchart showing another embodiment of the present invention.

FIG. 3 is a flow chart of a conventional reverse osmosis membrane device.

FIG. 4 is a flow chart of another conventional reverse osmosis membrane device.

[Explanation of symbols]

 12 High-pressure pump 14 Electric motor 16 Energy recovery turbine 18 Low-pressure pump 20 Power part 22 One-way clutch 23 Raw water 24 High-pressure reverse osmosis membrane unit 26 1st-stage concentrated water 28 1st-stage permeate 30 Low-pressure reverse osmosis membrane unit 32 Second-stage concentrated water 34 Second-stage permeated water

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideki Takahashi 5-5-16 Hongo, Bunkyo-ku, Tokyo Organo Corporation

Claims (1)

[Claims] 1. A high-pressure pump for pressurizing raw water to supply it to a high-pressure reverse osmosis membrane unit, an electric motor supplying drive power to this high-pressure pump, and a low-pressure reverse osmosis for pressurizing permeate of the high-pressure reverse osmosis membrane unit. A low pressure pump for supplying to the membrane unit, and an energy recovery turbine driven by concentrated water sent from the high pressure reverse osmosis membrane unit, which are configured by connecting their rotary shafts to one axis, and a high pressure reverse osmosis membrane unit. And a low-pressure reverse osmosis membrane unit, and the raw water supplied to the high-pressure pump is sequentially subjected to reverse osmosis treatment in the high-pressure reverse osmosis membrane unit and the low-pressure reverse osmosis membrane unit, and permeated water and A membrane separation device that takes out the concentrated water and recovers the driving energy of the pump from the concentrated water of the high-pressure reverse osmosis membrane unit by an energy recovery turbine.