JP2013146642A - Fluid membrane-separation power generation system - Google Patents

Abstract

The present invention reduces the operating cost of a membrane separation device by using energy generated in a pressure-type and cross-flow type membrane separation device without wasting it and using it for power generation processing. An object of the present invention is to provide a fluid membrane separation power generation system capable of obtaining a sufficient amount of separation fluid.
The present invention relates to a temperature difference power generator using at least a high-temperature fluid and a low-temperature fluid after separating a pressurized supply fluid into a permeation fluid and a concentrated fluid using a cross-flow separation membrane element. Electric power is generated using the concentrated fluid as a high temperature fluid.
[Selection] Figure 1

Description

  The present invention uses a cross-flow type separation membrane element using a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane), a reverse osmosis membrane (RO membrane) and the like. The present invention relates to a fluid membrane separation power generation system that separates a supply fluid into a permeation fluid and a concentrated fluid, and generates power using a temperature difference power generation device.

Membrane separation in the case of fluid separation is the shape and size of the pores of the membrane, the physical and chemical properties of the membrane, the shape and size of the substance to be treated, the physical and chemical properties, the pressure difference, etc. This is a separation method performed by a combination of three elements related to driving force. Membrane separation for water treatment depends on the type and size of the substance to be separated, microfiltration membrane (MF membrane), ultrafiltration membrane (UF membrane), nanofiltration membrane (NF membrane), reverse osmosis membrane (RO membrane) And so on. These separation membranes are preferably used for ultrapure water production, brine or seawater desalination, wastewater treatment, and the like. Furthermore, it can be used for advanced processing such as separation, removal and recovery of harmful components from dyeing wastewater, electrodeposition paint wastewater, sewage, etc., and concentration of active ingredients in food applications.

For example, seawater desalination, that is, seawater desalination treatment, generally uses a composite reverse osmosis membrane provided with a polyamide-based separation functional layer. This composite reverse osmosis membrane is provided in a pressure vessel as a spiral element and provided as a cross-flow type membrane separator. Furthermore, in such a seawater desalination membrane separation system, attempts have been made to recover the pressure remaining in the concentrated water by a recovery device and use it for driving a pump. (See Patent Document 1).

Regarding temperature difference power generation, a temperature difference power generation apparatus using a temperature difference between high-temperature warm seawater in the ocean surface and low-temperature cold seawater in the deep ocean is known. Such a temperature difference power generation device includes an evaporator, a condenser, a turbine, a generator, a pump, and the like, and these constituent devices are connected by a pipe. In the case of a closed cycle system, a working fluid such as ammonia sealed in the apparatus is sent to an evaporator in a liquid state, and heated at a temperature of a high-temperature fluid such as warm seawater to become steam. After the steam rotates the turbine and the generator to generate electric power, the steam is cooled by a low-temperature fluid such as cold seawater in a condenser and becomes liquid again. This is a method of generating electricity by repeating this process (see Patent Document 2).

Moreover, about the seawater desalination using a temperature difference power generation device, the fresh water generation method which condenses the vapor | steam obtained from the high temperature fluid in the open cycle system is proposed (refer patent document 3).

JP 2000-167358 A Japanese Patent Laid-Open No. 07-093611 International Publication No. 2007/020707 Pamphlet

In the conventional membrane separation apparatus as described above, for example, during the membrane separation by the reverse osmosis membrane method in seawater desalination, a pressure higher than the osmotic pressure of seawater, that is, about 5 to 7 MPa is required. The energy required for water occupies most of the operating cost of the seawater desalination membrane separation device, which increases the fresh water production cost. In response to this, efficiency has been studied by the method of recovering the residual pressure as described above, but it cannot be said to be sufficient because of its limitations in principle, and the global demand for water is increasing. At the same time, there is a need for further efficiency and reduction of water production costs. Also in the temperature difference power generation system, although desalination of seawater has been studied as described above, the so-called evaporation method is used, and it has been difficult to secure a sufficient amount of fresh water in the power generation system.

In the present invention, the energy generated in the pressure-type membrane separation apparatus is utilized without wasting it, and is used for power generation processing, thereby reducing the operating cost of the membrane separation apparatus and securing a sufficient amount of separation fluid. The purpose is to provide a system.

  The present invention provides a temperature difference power generation apparatus that supplies at least a high-temperature fluid and a low-temperature fluid after separating a pressurized supply fluid into a permeation fluid and a concentrated fluid using a cross-flow type separation membrane element. The present invention relates to a fluid membrane separation power generation system that generates electricity by supplying it as a fluid.

The low-temperature fluid is preferably a supply fluid before being supplied to the separation membrane element, and the concentrated fluid is preferably heated so that the temperature difference between the high-temperature fluid and the low-temperature fluid is 20 ° C. or more. Furthermore, when the concentrated fluid is heated, it is preferable to use solar energy.

The supply fluid is preferably seawater or water obtained by separating seawater, and the supply fluid is preferably pressurized at a pressure of 1 MPa to 10 MPa.

The present invention also relates to a fluid membrane separation power generation comprising a pressure pump, a cross flow separation membrane element that separates the fluid that has passed through the pressure pump, and a temperature difference power generation device that introduces the concentrated fluid separated from the separation membrane. About the system.

It is a block diagram which shows an example of the structure which implements this invention.

In the temperature difference power generation apparatus using at least a high temperature fluid and a low temperature fluid after separating a pressurized supply fluid into a permeation fluid and a concentrated fluid using a cross-flow type separation membrane element, the concentrated fluid is heated to a high temperature. It is a fluid membrane separation power generation system characterized by being supplied as a fluid.

The supply fluid used in the present invention is not limited as long as it can be separated into a permeation fluid and a concentrated fluid in a cross-flow type separation membrane element, production of ultrapure water, brine or seawater desalting, It can be used in well-known methods such as wastewater treatment, methods for separating harmful components from dyeing wastewater, electrodeposition paint wastewater, sewage, etc., and concentration of active ingredients in food applications. A fluid that continuously treats a certain amount such as irrigation water or seawater is preferable. Among these, seawater for desalination of seawater, and water obtained by pretreating the seawater and the wastewater by sand filtration, precipitation and / or membrane separation can be preferably used.

The supply fluid is pressurized and supplied to the separation membrane element. As the pressurizing method, a mechanical means using a known pressurizing pump can be used, and the pressure applied at this time may be appropriately determined according to the performance of the supply fluid and the separation membrane, but generally 1 MPa. It is preferably 10 MPa or less and more preferably 1.5 MPa to 8 MPa.

The separation membrane element is generally used by being loaded into a pressure vessel that can withstand the pressurization of the supply fluid, or processed into a pressure vessel integrated element. In the present invention, there is no limitation as long as it is a pressure separation type separation membrane element that uses a cross-flow method. However, as an example, a spiral type polyamide composite separation membrane element used for seawater desalination is described. To do.

A spiral separation membrane element is disclosed in FIGS. 2 and 3A of Japanese Patent Laid-Open No. 2000-167358.
As shown in Fig. 4, the separation membrane, the supply side channel material, and the permeate side channel material are spirally wound around the central tube (collection tube), and the end member, exterior material, etc. Fixed. At this time, each side of the separation membrane is adhered as necessary, and the supply fluid and the permeated fluid are not mixed.

Examples of the polyamide composite separation membrane include a porous support provided with a separation functional layer made of a polyamide polymer.

The porous support is not particularly limited as long as it can form a separation functional layer, and a porous support made of a polysulfone layer on a substrate such as a nonwoven fabric or a woven fabric is preferably used. In addition, a porous film such as polyimide, polyvinylidene fluoride, and epoxy can be used alone. At this time, the average pore diameter of the surface on which the separation functional layer of the porous support is provided is about 0.01 μm to 1 μm, and the thickness of the porous support is about 10 to 150 μm.

A known method can be used as the polyamide-based separation functional layer. For example, an aqueous solution coating layer containing a polyfunctional amine component is formed on a porous support, and the polyfunctional acid halide component is contained therein. The polyamide-based separation functional layer can be formed by contacting the solution. The contact time is usually 5 seconds to 5 minutes, and after the excess solution is removed, condensation polymerization is performed at the interface caused by the contact. Furthermore, it is preferable to dry in air at 15 ° C. to 35 ° C. for about 1 to 10 minutes, and to wash the membrane surface with deionized water after drying.

Examples of the polyfunctional amine component include aromatic, aliphatic, or alicyclic polyfunctional amines. Moreover, these polyfunctional amine components may be used alone or as a mixture. As the polyfunctional acid halide component, aromatic, aliphatic, or alicyclic polyfunctional acid halides can be used. These polyfunctional acid halide components may be used alone or as a mixture.

The temperature difference power generation device is limited as long as the concentrated fluid supplied from the separation membrane element is used as a high-temperature fluid, and a device that generates electricity based on the principle of these temperature differences using a separately supplied low-temperature fluid. However, a closed cycle system that repeats vaporization and liquefaction while the working fluid is sealed will be described as an example.

The concentrated fluid discharged from the separation membrane element and supplied to the temperature difference power generation device is appropriately heated as necessary and sent to the temperature difference power generation device as a high temperature fluid. The heating temperature of the concentrated fluid at this time is appropriately determined according to the vaporization temperature of the working fluid and the sealing pressure. preferable.

The method of heating the concentrated fluid is not particularly limited, and heating power, heating wire, solar heat, etc. can be used as appropriate according to the surrounding environment and device design, but from the viewpoint of energy efficiency, sunlight, solar heat, etc. The method of heating using solar energy is preferable. As a heating method, a material having a high thermal conductivity such as a metal may be used as a supply fluid or concentrated fluid pipe, and appropriate known heating may be performed on the portion. In addition to using a transparent pipe as the pipe, a concave mirror is installed at a position symmetrical to sunlight and the fluid is heated, or one side of the transparent pipe facing the position symmetrical to sunlight is used as a mirror surface. It is also preferable to collect solar energy into a fluid and heat it. The heating position is preferably performed on the pressurized supply fluid in consideration of heat transfer from the pressurizing pump. Furthermore, any of the separation membrane element may be used before membrane separation, after membrane separation, or within the separation membrane element, and these may be combined at a plurality of positions, but it is preferable to heat before membrane separation and / or after membrane separation. Since it is known that when the fluid is heated before the membrane separation, the permeation performance of the separation membrane can be improved when a fluid having a temperature higher than room temperature is supplied to the separation membrane element, the permeation performance of the separation membrane can be improved. Furthermore, since it can supply to a separation membrane element at fixed temperature, it becomes easy to control membrane separation performance uniformly. Further, when heating is performed after membrane separation, only the concentrated fluid used as the high-temperature fluid can be efficiently heated without wasting heating energy. Therefore, it is preferable to preheat the pressurized supply fluid to about 40 ° C. or less before membrane separation and to heat to the required level after membrane separation.

The low-temperature fluid supplied to the temperature difference power generation device is not particularly limited except that it is a fluid that is not frozen and has no malfunction in flow, and preferably has a low temperature as much as possible. It is preferable to use a fluid of less than or equal to ° C. For example, a fluid other than the separation target fluid such as supply fluid to the separation membrane, river water, seawater, deep ocean water, or alcohol can be used. It is preferable to use a part of the supply fluid to the membrane, more preferably the supply fluid before pressurization.

The temperature difference between the low-temperature fluid and the high-temperature fluid is preferably 20 ° C. or higher, and more preferably 25 ° C. or higher when a highly efficient apparatus using ammonia as a working fluid, such as a Carina cycle or Uehara cycle, is used. The higher the temperature difference, the better. However, the temperature difference from the viewpoint of energy efficiency is 90 ° C. or less, preferably 50 ° C. or less.

When the supply fluid passes through the pump for pressurization, the temperature of the supply fluid rises by 2 to 3 ° C. due to the transfer of thermal energy. This is because the difference in operating temperature required in the above wafer cycle is about 25 ° C., so this thermal energy is equivalent to about 10%, and this energy can be used without surplus.

As the temperature difference power generation device, there are an open cycle system, a closed cycle system, and a hybrid cycle system thereof, and an appropriate method can be used. These are commonly composed of an evaporator, a condenser, a turbine, a generator, a pump, and the like, and these components are connected by a pipe. For example, in the case of a closed cycle system in which sea surface water is a high-temperature fluid and deep ocean water is a low-temperature fluid, a working fluid such as ammonia enclosed in this device is sent to the evaporator in a liquid state, and the inside of the evaporator Then, the steam is heated at the temperature of the surface water of the sea surface and becomes steam. After generating power by rotating the turbine and the generator, the steam is cooled by the condenser having the temperature of the deep sea water and becomes liquid again. Power can be generated by repeating this process.

The evaporator and the condenser are not particularly limited as long as the high-temperature fluid, the low-temperature fluid, and the working fluid are not mixed, heat exchange can be appropriately performed, and further, corrosion is not caused by the fluid. Can do. In the evaporator, it is preferable to reduce the pressure from atmospheric pressure in order to facilitate vaporization. In addition, it is preferable to appropriately design the size and shape of the evaporator and the condenser in consideration of the heat exchange efficiency. As the turbine and the generator, commercially available ones can be used as long as they are not corroded by the working fluid vapor.

Examples of the working fluid include ammonia, a chlorofluorocarbon compound, a hydrocarbon compound, water, and a mixture thereof. From the viewpoint of operation efficiency, the working fluid is a mixture of ammonia and water, and a substance using 70 to 95% by weight of ammonia is used. It can be particularly preferably used.

The pipe for connecting the component devices is not particularly limited, and a metal or resin pipe can be used, but a pipe having a particularly high heat insulating effect can be preferably used. If necessary, it is preferable to use an appropriate heat insulating material in order to increase efficiency.

In addition, in the system of the temperature difference power generation device alone, a pump for flowing the high temperature fluid and the low temperature fluid is required respectively. However, according to the present invention, the fluid pressure of the membrane separation process can be used. Flow pumps other than the pump that flows the working fluid in the device, that is, for high-temperature fluids, and when the supply fluid is used for low-temperature fluids, any pump for low-temperature fluids can be omitted and operated. High energy saving effect.

The high-temperature fluid and the low-temperature fluid after being used for power generation in the temperature difference power generation device are not particularly limited, but it is preferable that the energy and fluid itself be returned to the membrane separation system and circulated. The high temperature fluid is preferably recovered and reused by using the pressure energy recovery device. Examples of the pressure energy recovery device include the PX series manufactured by Energy Recovery. Further, in order to effectively utilize the high temperature of the high-temperature fluid, a method of desalination by various evaporation methods can be preferably used in combination. The low-temperature fluid is preferably returned as the supply fluid to the separation membrane element, but a method of supplying the pressure energy as a supply fluid to the pressure energy recovery device and supplying pressure energy to the separation membrane element is preferably used. .

In the case of using the pressure energy recovery device, the pipes and devices up to the recovery device need to have a pressure resistant configuration capable of withstanding a high fluid pressure. For this reason, it is preferable to provide the pressure energy recovery device immediately after the separation membrane for supplying the pressurized supply fluid so that the pressure-resistant configuration is minimized, and moderately reduce the pressure of the fluid thereafter. Although the pressure after pressure reduction at this time is not particularly limited, it is preferably about 0.1 to 2 MPa.

Although the specific example of the fluid membrane separation power generation system in this invention is shown based on FIG. 1 below, this invention is not limited to this.

FIG. 1 is an example of a fluid membrane separation power generation system of the present invention in which a temperature difference power generation system is provided after a seawater desalination reverse osmosis membrane system. This will be explained step by step.

(Seawater desalination reverse osmosis membrane system)
First, raw seawater (raw water) 101 is taken from the intake pump 1 and stored in the UF membrane filtration water tank 5 through the sand filtration device 2 and the ultrafiltration membrane (UF membrane) pretreatment device 3. At this time, about 1 ppm of sodium hypochlorite was added from the drug injection device 4 for the purpose of suppressing the growth of microorganisms and sterilization. Thereafter, the water stored in the UF membrane filtration water tank 5 is fed by the supply pump 6 at a pressure of about 0.5 MPa. At that time, in order to suppress the chemical degradation of the RO membrane by sodium hypochlorite injected by the drug injection device 4, 3 ppm of sodium bisulfite as a reducing agent is added from the drug injection device 7 and further hardly soluble salts ( In order to suppress the generation of scale, 3 ppm of a scale inhibitor (Permatreat PC191 manufactured by Nalco) was injected from the drug injection device 8. At this time, the feed water at 20 ° C. is pressurized to about 5.5 MPa by the high-pressure pump 9, and the reverse osmosis membrane (RO membrane) in which the spiral element of the polyamide-based separation membrane is accommodated in the pressure-resistant container at a water temperature of 23 ° C. ) It was introduced into the separation device 10 and separated into permeated water 103 and concentrated water 104.

This concentrated water 104 is immediately recovered by the pressure energy recovery device 21, transfers the pressure energy to the supply water taken from before the high-pressure pump 9, and is mixed with the RO membrane supply water 102 after the high-pressure pump 9. To do. On the other hand, the concentrated water 104 depressurized by the pressure energy recovery device 21 is heated by the solar heating device 11 configured with black outdoor piping, and the concentrated water that has reached 30 ° C. is further heated by a heater (electric boiler) 12. Heated to 50 ° C. In addition, the heating degree of the electric boiler 12 was set to be raised to 50 ° C. in conjunction with the heating state of the heating device 11. This heated concentrated water was supplied to the evaporator 13 as a high-temperature fluid 105 used in the temperature difference power generation system.

(Temperature difference power generation system)
In the temperature difference power generation system, a mixture of 90 wt% ammonia and 10 wt% pure water was used as the working fluid 107. Heat exchange was performed between the high-temperature fluid 105 and the working fluid 107 in the evaporator 13, and the working fluid vapor and the working fluid liquid were separated in the gas-liquid separator 15. This working fluid vapor was sent to the turbine 16 to generate electricity by rotating the generator 17, and this electric power was used as power for the high-pressure pump 9. Thereafter, the working fluid vapor discharged from the turbine 16 is sent to the condenser 14, exchanges heat with the low temperature fluid 106, becomes a liquid, and enters the storage tank 19. The cryogenic fluid 106 uses water after the supply pump 6 and before the drug injection devices 7 and 8, and the cryogenic fluid 106 after being used in the condenser 14 is returned to the UF membrane filtration water tank 5. On the other hand, the working fluid liquid was once stored in the storage tank 18, sent to the condenser 14, and then stored in the storage tank 19. The working fluid stored in the storage tank 19 is sent to the evaporator 13 by using the pump 20, and electricity is generated by repeating this operation.

As described above, the present invention provides a fluid membrane separation power generation system using fluid membrane separation and temperature difference power generation. In this system, the pressure and heat energy applied to the fluid of the fluid membrane separation, which has been wasted until now, can be consumed without wasting without affecting the performance of the fluid separation in the membrane separation. For example, the energy of 2 to 3 ° C. applied to the fluid by pressurization for membrane separation is about 10% of energy for the temperature difference of 20 to 30 ° C. that can drive the high-efficiency temperature difference power generator. Therefore, at least the same level of energy saving can be realized. Further, by using the fluid flow pressure indispensable for fluid membrane separation, the power generation function can be operated without using a pump for flowing the high temperature fluid and the low temperature fluid, which is indispensable for driving the temperature difference power generation device.

DESCRIPTION OF SYMBOLS 1 Intake pump 2 Sand filtration device 3 Ultrafiltration membrane (UF membrane) pretreatment device 4, 7, 8 Drug injection device 5 UF membrane filtration water tank 6 Supply pump 9 High-pressure pump 10 Reverse osmosis membrane (RO membrane) filtration device 11 Solar heat Heating device 12 Heater (electric boiler)
13 Evaporator 14 Condenser 15 Gas-Liquid Separator 16 Turbine 17 Generator 18, 19 Storage Tank 20 Working Fluid Pump 21 Pressure Energy Recovery Device 101 Raw Water 102 RO Membrane Supply Water 103 Permeated Water 104 Concentrated Water 105 Hot Fluid 106 Cold Fluid 107 Working fluid

Claims (7)

After the pressurized supply fluid is separated into a permeation fluid and a concentrated fluid using a cross-flow separation membrane element, the concentrated fluid is used as a high temperature fluid in a temperature difference power generation apparatus that uses at least a high temperature fluid and a low temperature fluid. A fluid membrane separation power generation system characterized by generating power. 2. The fluid membrane separation power generation system according to claim 1, wherein a supply fluid before being supplied to the crossflow separation membrane element is used as the low temperature fluid. The fluid membrane separation power generation system according to claim 1 or 2, wherein the concentrated fluid is heated so that a temperature difference between the high temperature fluid and the low temperature fluid becomes 20 ° C or more. The fluid membrane separation power generation system according to claim 3, wherein heating of the concentrated fluid uses solar energy. The fluid membrane separation power generation system according to claim 1 or 2, wherein the supply fluid is seawater or water obtained by separating seawater. The fluid membrane separation power generation system according to claim 1 or 2, wherein the supply fluid is pressurized at a pressure of 1 MPa to 10 MPa. A fluid membrane separation power generation system comprising a pressurization pump, a cross-flow type separation membrane element that separates a fluid that has passed through the pressurization pump, and a temperature difference power generation device that introduces a concentrated fluid separated from the separation membrane.

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