CN113292123A - Compressed gas energy storage type membrane distillation seawater desalination and desalination system and seawater desalination process thereof - Google Patents
Compressed gas energy storage type membrane distillation seawater desalination and desalination system and seawater desalination process thereof Download PDFInfo
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- CN113292123A CN113292123A CN202110605428.9A CN202110605428A CN113292123A CN 113292123 A CN113292123 A CN 113292123A CN 202110605428 A CN202110605428 A CN 202110605428A CN 113292123 A CN113292123 A CN 113292123A
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- C02F1/00—Treatment of water, waste water, or sewage
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- C02F1/08—Thin film evaporation
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/14—Treatment of water, waste water, or sewage by heating by distillation or evaporation using solar energy
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
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- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
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- Y02A20/138—Water desalination using renewable energy
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Abstract
The invention discloses a compressed gas energy storage type membrane distillation seawater desalination and desalination system and a seawater desalination process thereof, and belongs to the field of desalination and water treatment. The system comprises a water taking pump, a seawater pretreatment unit, a membrane distillation unit, a heat collection unit, an energy obtaining unit and an energy storage unit. The invention utilizes renewable energy sources such as solar energy, wind energy and the like to supply power and heat, combines the energy storage technology and the membrane distillation technology to realize a stable desalination process, and has better energy utilization efficiency; the preheater is used for recovering the waste heat of the strong brine, so that the heat economy is good, and the water production flexibility is good by controlling the mixed salinity of the desalted water and the strong brine; the problems of instability, discontinuity and the like when renewable energy is obtained are solved by utilizing the compressed gas energy storage system, and the energy storage system can be assisted to supply power. The compressed gas energy storage type membrane distillation seawater desalination system is simple and compact in structure, saves physical space, and is simple and convenient to install and maintain.
Description
Technical Field
The invention relates to the field of desalination and water treatment, relates to a desalination and desalination technology of membrane distillation seawater or brackish water capable of storing energy, and particularly relates to a compressed gas energy storage type membrane distillation seawater desalination and desalination system and a seawater desalination process thereof.
Background
Water resources and energy resources are important bases for survival and development of human society, and the environmental problems caused by excessive exploitation of underground water focus the sight of people on sufficient seawater resources. Nowadays, seawater desalination technology is widely applied worldwide, and can be divided into two types, thermal desalination and membrane desalination, according to the water production principle. The membrane distillation technology belongs to a new seawater desalination technology, and has the advantages of pure distillate, normal-pressure operation and low requirement on an external heat source, so that the membrane distillation technology is widely concerned. However, the membrane distillation process has high energy consumption, and the water production efficiency is different from that of the traditional methods such as reverse osmosis, so that the large-scale industrial popularization is not yet realized. The utilization of renewable energy sources such as solar energy and the like makes membrane distillation promising as a competitive desalination technology. The solar energy drives the membrane distillation seawater desalination system, reduces the unit water production energy consumption of the thermal membrane coupling system to the maximum extent, and has wide prospect for promoting the industrial application of the membrane distillation seawater desalination.
At present, a mode that a low-temperature multi-effect seawater evaporation system (MEE) and a reverse osmosis membrane seawater desalination System (SWRO) are operated in parallel is mostly adopted in a hot membrane coupling system, namely a hot method system and a membrane method system share one seawater pretreatment unit, and then, after inflow seawater is treated by the two systems which are operated independently, prepared fresh water is mixed according to a certain proportion, so that the concentration requirement of water is met. For example, the solar heat collecting pipe bundle type seawater desalination device mentioned in chinese patent CN 109970151 a adopts a hydrophobic microporous membrane for distillation desalination, and places a membrane module above a compound parabolic concentrator, thereby solving the problem of non-uniform concentration effect when solar energy is used for heating. Chinese patent CN105771662A proposes a membrane distillation device using a photovoltaic solar heat pump, which supplies power to the heat pump by means of a photovoltaic power generation technology, and reduces energy consumption for processing feed liquid. Chinese patent CN108083369A proposes an integrated seawater desalination system that utilizes a series-connected photovoltaic photo-thermal module to heat and generate power for a membrane distillation system at the same time, which improves the integration level and convenience between systems. Chinese patent CN101302048A proposes a membrane distillation seawater desalination system, in which the seawater outlet and the steam outlet of the membrane module are connected to a heat pump to realize the recovery of steam heat from seawater, thereby improving the energy utilization efficiency. Chinese patent CN103708665A proposes a wind power and solar power complementary seawater desalination system, which is coupled in series with a multi-effect evaporation desalination system to provide inlet water for a membrane desalination unit.
The thermal desalination units of the thermal film coupling system all adopt a multi-effect seawater evaporation system, have higher requirements on physical space and are complex to install and maintain. The thermal method unit does not adopt an effective energy recovery technology, the energy utilization rate is not high, renewable energy sources such as solar energy, wind energy and the like for power generation are sensitive to changes of factors such as seasons, climates and the like, the structure of a coupling system is not flexible enough, and the coupling system has great limitation on different process requirements.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a compressed gas energy storage type membrane distillation seawater desalination system and a seawater desalination process thereof, so as to solve the problems that the energy utilization rate of a hot method unit is not high and the structure of a coupling system is not flexible in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a compressed gas energy storage type membrane distillation seawater desalination and desalination system, which comprises a water taking pump, a seawater pretreatment unit, a membrane distillation unit, a heat collection unit, an energy obtaining unit and an energy storage unit, wherein the water taking pump is connected with the seawater pretreatment unit;
the seawater pretreatment unit is used for purifying seawater;
the membrane distillation unit is used for desalting the purified seawater and comprises a heater, a membrane distillation assembly and a fresh water collecting tank; wherein, the tube pass inlet of the heater is communicated with the water outlet of the seawater pretreatment unit, the tube pass outlet of the heater is communicated with the inlet of the membrane distillation assembly, and the shell pass outlet of the heater is connected with the heat collection unit; a membrane front outlet of the membrane distillation assembly is connected with the seawater pretreatment unit, a membrane rear outlet of the membrane distillation assembly is respectively connected with a fresh water collecting tank and an adjusting valve through two branches, and the fresh water collecting tank is used for collecting fresh water under different opening degrees of the adjusting valve;
the heat collection unit is used for collecting solar energy, converting the solar energy into heat energy and providing a heat source for the heater;
the energy obtaining unit is used for converting the obtained renewable energy into electric energy and supplying power to the water taking pump, the heat collecting unit and the energy storage unit;
the energy storage unit is used for storing the electric energy in the form of compressed gas, and when the energy obtaining unit is influenced by meteorological conditions to cause insufficient or unstable electric energy, the energy storage unit assists the energy obtaining unit to supply power.
Furthermore, the seawater pretreatment unit comprises pretreatment equipment and a preheater, wherein a water inlet of the pretreatment equipment is connected with the water taking pump, and a water outlet of the pretreatment equipment is connected with the preheater; the preheater comprises a tube side and a shell side, a tube side water inlet of the preheater is communicated with a water outlet of the pretreatment equipment, a tube side water outlet of the preheater is communicated with a tube side water inlet of the heater, a shell side water inlet of the preheater is communicated with a membrane front water outlet of the membrane distillation assembly, and a shell side water outlet of the preheater outputs strong brine.
The heat collecting unit comprises a solar heat collector, a circulating pump, a water tank and an electric heater;
the water tank is a separated water tank, the top of the water tank is provided with a first water inlet and a first water outlet, the bottom of the water tank is provided with a second water inlet, one side of the water tank is provided with a second water outlet, and a separation plate is arranged in the water tank and used for separating the first water inlet, the first water outlet, the second water inlet and the second water outlet; the second water outlet of the water tank is communicated with the water inlet of the circulating pump, the water outlet of the circulating pump is communicated with the water inlet of the solar thermal collector, and the water outlet of the solar thermal collector is connected with the first water inlet of the water tank; a first water outlet of the water tank is communicated with a shell pass water inlet of the heater, and a shell pass water outlet of the heater is communicated with a second water inlet of the water tank;
the electric heater is electrically connected with the energy storage unit and/or the energy obtaining unit.
Further, the solar heat collector is a flat plate type solar heat collector or a vacuum tube type solar heat collector.
Further, the energy obtaining unit adopts a photoelectric plate and/or a wind generating set.
Further, the membrane distillation assembly employs one or more of a direct contact membrane distillation assembly, an air gap membrane distillation assembly, and a vacuum membrane distillation assembly.
Still further, the membrane distillation assembly is a single or multi-stage membrane distillation assembly.
The energy storage unit adopts a compressed gas energy storage assembly; the compressor and the turboexpander of the compressed gas energy storage assembly are adjustable in stage number, and the energy storage medium adopts air or carbon dioxide as compressed gas and is used for storing acting energy to be converted.
Furthermore, the compressed gas energy storage assembly comprises a compressor, a turbo expander, a gas storage tank and a motor, wherein the motor is electrically connected with the compressor, the compressor is communicated with the gas storage tank, and the gas storage tank is connected with the turbo expander; the motor drives the compressor to move by utilizing the electric energy input by the energy obtaining subsystem, and the compressed gas is stored in the gas storage tank; when the electric energy of the energy obtaining subsystem is insufficient or unstable, the compressed gas stored in the gas storage tank pushes the turboexpander to do work, and the mechanical energy is converted into electric energy to be output.
Further, the compressed gas is air or carbon dioxide.
Furthermore, the fresh water collecting tank can be communicated with a strong brine outlet pipeline, and the desalted water with salinity, which meets different process requirements, can flow out by adjusting the water outlet proportion of the two outlets through the adjusting valve.
The invention also discloses a process for desalinating seawater based on the compressed gas energy storage type membrane distillation seawater desalination and desalination system, which comprises the following steps:
1) inputting the seawater to be treated into a seawater pretreatment unit, and purifying the seawater;
2) the purified seawater enters a heater tube pass, and the seawater in the heater tube pass is heated by a heat collection unit;
3) the heated seawater enters a membrane distillation assembly, and is separated by the membrane distillation assembly to obtain condensed desalted water and preheated strong brine.
Further, a step of preheating the purified seawater by utilizing the preheated strong brine is also included between the steps 1) and 2), and the preheated strong brine is changed into the strong brine after losing heat.
Further, in the step 2), water in the heat collecting unit is driven by the circulating pump, flows through the solar heat collector for heating, flows into the heater through the water tank for heating the seawater on the tube side, and the temperature of the seawater is increased after the seawater absorbs heat;
further, in the step 3), the preheated strong brine obtained by separating through the membrane distillation assembly is discharged from the bottom of the membrane distillation assembly, enters the seawater pretreatment unit again to exchange heat with the input pretreated seawater, and meanwhile, the condensed desalted water and the preheated strong brine are mixed in proportion through the regulating valve and then enter the fresh water collecting tank to obtain desalted water with required salinity.
Further, when the electric energy of the energy obtaining unit is insufficient or unstable, the compressed gas energy storage unit converts the stored compression work into electric energy to be output, and the electric energy replaces or assists a photoelectric plate and/or a wind generating set in the energy obtaining unit to supply power to the water taking pump, the circulating pump and the electric heater.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a compressed gas energy storage type membrane distillation seawater desalination system, which comprises the following steps that firstly, a heat collection unit is adopted to convert solar energy into heat energy so as to provide a heat source for a membrane distillation assembly; renewable energy sources are converted into electric energy by adopting the energy obtaining unit to supply power to the seawater pretreatment unit, the heater, the heat collection unit and the compressed gas energy storage unit, and the adopted energy sources are renewable clean energy sources, so that energy conservation, environmental protection and low-carbon emission are realized while the problem of water resource shortage is solved; secondly, the seawater is desalted and desalted by adopting a membrane distillation technology, so that the requirements of temperature and pressure working conditions in the traditional thermal method or membrane method desalting process are reduced; and thirdly, converting the electric energy abundant in the energy obtaining unit into compressed gas by using the compressed gas energy storage unit for storage, and assisting the energy obtaining subsystem to supply power when the electric energy of the energy obtaining subsystem is insufficient or unstable so as to provide a controllable energy source with stability and high energy storage density for the power supply of the compressed gas energy storage type membrane distillation seawater desalination system. The compressed gas energy storage type membrane distillation desalination system has high energy utilization rate, and avoids the influence of factors such as seasons, climate and the like on the energy obtaining unit, so that the structure of the compressed gas energy storage type membrane distillation desalination system is not flexible. The invention has the characteristics of compact structure, simplicity and flexibility, and can be used for small-sized seawater desalination processes and large-sized seawater desalination plants or the transformation of desalination processes.
Furthermore, a preheater is arranged between the seawater pretreatment unit and the heater, preheated strong brine processed by the membrane distillation assembly is introduced into the tube pass of the preheater, the purified seawater is preheated by utilizing the heat carried by the preheated strong brine, and the water yield and the energy utilization rate of the membrane distillation assembly are increased by recycling the waste heat of the preheated strong brine.
Furthermore, the ratio of the condensed desalted water to the strong brine/the preheated strong brine is adjusted to obtain desalted water with different salinity, so that the salt-containing desalted water required by the downstream process is provided.
Further, the heat collecting unit comprises a solar heat collector, a circulating pump and a water tank, wherein the solar heat collector directly converts solar energy into heat energy, circulating water in the water tank is conveyed to the solar heat collector through the circulating pump, the solar heat collector heats the circulating water, the heated circulating water flows back to the water tank again, the heated circulating water in the water tank flows into the shell pass of the heater to exchange heat with seawater in the shell pass, and the circulating water losing heat flows back to the water tank again. The seawater is continuously heated by the heat generated by the solar energy through the reciprocating circulation, so that the energy consumption and the loss of a heat transfer medium in the seawater desalination process are reduced.
Furthermore, the electric heater is arranged in the water tank, and the electric energy provided by the energy obtaining unit or the compressed gas energy storage unit can be used for heating the circulating water in the water tank in rainy days, so that the compressed gas energy storage type membrane distillation seawater desalination system is not influenced by weather, and the all-weather seawater desalination is realized.
Drawings
FIG. 1 is a schematic structural diagram of a membrane distillation seawater desalination system capable of storing energy according to the present invention;
wherein: 1-water taking pump; 2-pretreatment equipment; 3-a preheater; 4-a heater; 5-a membrane distillation assembly; 6-adjusting the valve; 7-a fresh water collection tank; 8-a solar heat collector; 9-a circulating pump; 10-a water tank; 11-an electric heater; 12-photoelectric plate, 13-compressed gas energy storage unit.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
the invention discloses a compressed gas energy storage type membrane distillation seawater desalination system which comprises a water taking pump 1, a seawater pretreatment unit, a membrane distillation unit, a heat collection unit, an energy obtaining unit and an energy storage unit, wherein the seawater pretreatment unit is connected with the membrane distillation unit;
the seawater pretreatment unit is used for purifying seawater;
the membrane distillation unit is used for desalting the purified seawater and comprises a heater 4, a membrane distillation component 5 and a fresh water collecting tank 7; the heater 4 has a tube side and a shell side; the heat collecting unit converts solar energy into heat energy and provides a heat source for the heater 4; the energy obtaining unit converts the obtained renewable energy into electric energy to supply power for the water taking pump 1, the seawater pretreatment unit, the heater 4, the membrane distillation assembly 5, the heat collection unit and the energy storage unit;
the energy storage unit is used for storing the electric energy in the form of compressed gas, and when the energy obtaining unit is influenced by meteorological conditions to cause insufficient or unstable electric energy, the energy storage unit assists the energy obtaining unit to supply power.
The energy obtaining unit is used for converting the obtained renewable energy into electric energy and supplying power to the water taking pump 1, the heat collecting unit and the energy storage unit, and the energy obtaining unit is electrically connected with the water taking pump 1, the circulating pump 9, the electric heater 11 and the compressed gas energy storage unit 13; the compressed gas energy storage unit 13 is electrically connected with the water taking pump 1, the circulating pump 9 and the electric heater 11.
The seawater pretreatment unit comprises pretreatment equipment 2 and a preheater 3, wherein a water inlet of the pretreatment equipment 2 is connected with a water taking pump 1, and a water outlet of the pretreatment equipment 2 is connected with the preheater 3; the preheater 3 comprises a tube side and a shell side, a tube side water inlet of the preheater 3 is communicated with a water outlet of the pretreatment equipment 2, a tube side water outlet of the preheater 3 is communicated with a tube side water inlet of the heater 4, a shell side water inlet of the preheater 3 is communicated with a membrane front water outlet of the membrane distillation assembly 5, and a shell side water outlet of the preheater 3 outputs strong brine.
Preferably, the condensed desalted water outlet is converged with a strong brine outlet/preheated strong brine outlet pipeline, and the desalted water with salt content of different salinity is obtained by adjusting the proportion of the condensed desalted water to the strong brine/preheated strong brine.
Preferably, a membrane rear water outlet of the membrane distillation assembly 5 is communicated with a fresh water collecting tank 7, and the fresh water collecting tank 7 collects salt-containing desalted water.
Preferably, the membrane distillation module 5 is one or more of a direct contact membrane distillation module, an air gap membrane distillation module and a vacuum membrane distillation module, the membrane distillation module being a single or multi-stage membrane distillation module.
Preferably, the energy obtaining unit comprises one or both of a photovoltaic panel 12 or a wind power generator set.
Preferably, the heat collecting unit comprises a solar heat collector 8, a circulating pump 9 and a water tank 10, wherein the water tank 10 is provided with two water inlets and two water outlets; a first water outlet of the water tank 10 is communicated with a water inlet of a circulating pump 9, a water outlet of the circulating pump 9 is communicated with a water inlet of a solar heat collector 8, and a water outlet of the solar heat collector 8 is connected with the first water inlet of the water tank 10; and a second water outlet of the water tank 10 is communicated with a shell pass water inlet of the heater 4, and a shell pass water outlet of the heater 4 is communicated with a second water inlet of the water tank 10. Circulating water in the water tank 10 is driven by the circulating pump 9, flows through the solar heat collector 9 for heating, and the heated circulating water flows back to the water tank 10; the heated circulating water flows into the shell pass of the heater 4 to exchange heat with the seawater on the tube pass of the heater 4, the circulating water after heat exchange flows back to the water tank 10 again, and the circulating water is circulated in such a way to supply heat to the seawater uninterruptedly.
Preferably, the solar collector 8 is a flat plate collector or a vacuum tube collector.
Further, an electric heater 11 is further arranged inside the water tank 10, and the electric heater 11 is electrically connected with the compressed gas energy storage unit and/or the energy obtaining unit. In rainy days, the electric energy provided by the energy obtaining unit or the compressed gas energy storage unit can be adopted to heat the circulating water in the water tank, so that the compressed gas energy storage type membrane distillation seawater desalination system is not influenced by weather, and the all-weather seawater desalination is realized.
Preferably, the system further comprises a water taking pump 1 communicated with the water inlet of the seawater pretreatment unit, and the water inlet of the water taking pump 1 is communicated with seawater.
Preferably, the compressed gas energy storage unit 13 comprises a compressor, a turboexpander, a gas storage tank and a motor, wherein the motor is electrically connected with the compressor, the compressor is communicated with the gas storage tank, and the gas storage tank is connected with the turboexpander; the motor drives the compressor to move by utilizing the electric energy input by the energy obtaining subsystem, and the compressed gas is stored in the gas storage tank; when the electric energy of the energy obtaining subsystem is insufficient or unstable, the compressed gas stored in the gas storage tank pushes the turboexpander to do work, the mechanical energy is converted into electric energy to be output, and the compressed gas is air or carbon dioxide.
The invention discloses a method for desalinating seawater based on the compressed gas energy storage type membrane distillation seawater desalination system, which utilizes an energy obtaining unit to supply power to a seawater pretreatment unit, a heater, a membrane distillation assembly and a heat collection unit, and comprises the following steps:
1) inputting the seawater to be treated into a seawater pretreatment unit, and purifying the seawater;
2) the purified seawater enters a heater tube pass, and the seawater in the heater tube pass is heated by a heat collection unit;
3) the heated seawater enters a membrane distillation assembly, and is separated by the membrane distillation assembly to obtain condensed desalted water and preheated strong brine.
Preferably, a step of preheating the purified seawater by using the preheated strong brine is further included between the steps 1) and 2), and the preheated strong brine loses heat and then becomes the strong brine. When the electric energy of the energy obtaining unit is insufficient or unstable, the compressed gas energy storage unit converts the stored compressed gas into electric energy to be output, and the energy obtaining unit is assisted to supply power.
Example 1:
as shown in fig. 1, a compressed gas energy storage type membrane distillation desalination system mainly comprises: the device comprises a water taking pump 1, pretreatment equipment 2, a heater 4, a membrane distillation assembly 5, a solar thermal collector 8, a photoelectric panel 12 and a compressed gas energy storage unit 13. Wherein, the inlet of the water taking pump 1 is connected with a water source to be desalted, and the outlet is connected with the water inlet of the pretreatment device 2; the delivery port of pre-treatment device 2 communicates with the tube side water inlet of pre-heater 3, the tube side and shell side outlet of pre-heater 3 link to each other with the entry of heater 4 and preheating strong brine export respectively, the tube side and shell side outlet of heater 4 link to each other with the entry of membrane distillation subassembly 5 and water tank 10 among the heating system respectively, the export (output preheating strong brine) before the membrane of membrane distillation subassembly 5 and the export (output condensation desalination) link to each other with the shell side (output strong brine after the heat exchange) and the fresh water collection tank 7 of pre-heater 3 respectively, strong brine delivery port and condensation desalination are joined through the pipeline, be equipped with governing valve 6 on the pipeline, through the aperture of control governing valve 6, obtain the desalination water of different salinity.
And a solar heat collecting plate 8 in the heat collecting unit is connected with a circulating pump 9 and a water tank 10 and is used for collecting solar radiation and heating circulating water. In addition, an electric heater 11 is arranged in the water tank 10, the electric heater 11 is electrically connected with the compressed gas energy storage unit, and the electric heater 11 heats circulating water in the water tank 10. The water tank 10 is provided with two water inlets and two water outlets; the first water outlet of the water tank 10 is communicated with the water inlet of the circulating pump 9, the water outlet of the circulating pump 9 is communicated with the water inlet of the solar heat collector 8, and the water outlet of the solar heat collector 8 is connected with the first water inlet of the water tank 10. Circulating water in the water tank 10 is driven by a circulating pump 9 and flows through a solar heat collector 8 to be heated, and the heated circulating water flows back to the water tank 10; the heated circulating water flows into the shell pass of the heater 4, exchanges heat with the raw water flowing through the tube pass of the heater 4, and flows back to the water tank 10 again after the heat exchange, so that the circulating water circulates in a reciprocating way to supply heat to the seawater without interruption.
The photoelectric plate 12 in the energy obtaining unit is electrically connected with electric equipment such as an electric heater 11, a circulating pump 9, a water taking pump 1 and a compressed gas energy storage unit 13 to supply power to the whole system; the compressed gas energy storage unit 13 converts electric energy into mechanical energy of compressed gas for storage, outputs the energy stored in the compressed gas as electric energy by the expander through work when electric power is required, and supplies power for connected electric equipment such as the electric heater 11, the circulating pump 9 and the water taking pump 1. The compressed gas energy storage assembly 13 is composed of auxiliary equipment such as a compressor, a turbo expander, a gas storage tank, a motor, a valve, instruments and the like.
The compressed gas energy storage type membrane distillation desalination and desalination system comprises:
the seawater is transported to the pretreatment device 2 by the water pump 1 and then flows through the tube pass of the preheater 3 and the heater 4. Water in the heat collection unit is driven by a circulating pump 9, flows through a solar heat collector 8 for heating, flows into the shell pass of the heater 4 through a water tank 10 for heating seawater in the tube pass of the heater 4, and the temperature of the seawater rises after the seawater absorbs heat. Then enters a membrane distillation assembly 5, the seawater is phase-changed after reaching the evaporation temperature, the preheated strong brine is discharged from a membrane front outlet of the membrane distillation assembly 5, enters a shell pass of a preheater 3 to exchange heat with the inflow seawater (the preheated strong brine loses heat and becomes strong brine), meanwhile, the condensed desalted water is discharged from a membrane rear outlet of the membrane distillation assembly 5, and is proportionally mixed with the strong brine through an adjusting valve 6 and then enters a fresh water collecting tank 7 to obtain the desalted water with the required salinity.
According to the invention, by using the methods of generating power by using renewable energy sources such as wind energy, solar energy and the like and recovering waste heat, the energy utilization efficiency of the membrane distillation system is increased, the energy consumption of the system is reduced, and the water yield is improved; according to the water production requirement and the actual operation condition, the salinity of the produced fresh water is adjusted by utilizing the opening degree of the adjusting valve, so that the method has high flexibility; the energy is stored by combining the compressed gas energy storage unit, and compared with the traditional power supply storage mode, the storage device has better stability; in addition, the whole seawater desalination system has simple and compact structure, saves physical space and is simple and convenient to install and maintain. Meanwhile, the coupling system has good applicability, not only can be used for small-sized seawater desalination processes of ships, islands and coastal areas, but also can be easily coupled with other multistage desalination systems for capacity expansion, and can be used for large-sized seawater desalination processes.
The innovation of the invention is that an energy storage system is also integrated in the conventional membrane distillation system. The membrane distillation has the advantages that the membrane distillation can be driven by renewable energy sources such as solar energy, wind energy and the like, but the renewable energy sources are greatly influenced by meteorological conditions and are unstable. Therefore, the energy storage system is used for storing surplus energy for use when the energy obtained by the rain and the like is insufficient. Therefore, in the system of the invention, in the sufficient sunshine period and the sufficient wind power period, the energy obtaining unit can continuously supply power to the compressed gas energy storage unit and the seawater desalination system at the same time, and when the sunshine or the wind power is insufficient, the energy stored by the energy storage unit is released to supply power to the seawater desalination system.
In conclusion, the invention has the following advantages:
(1) the desalination system for preparing fresh water by adopting the membrane distillation technology has the advantages that higher membrane permeation pressure is not required to be provided in the membrane method desalination process, and seawater is not required to be heated to boiling point temperature;
(2) the heat collection unit is adopted for supplying heat, and the electric energy provided by the energy obtaining unit is used for assisting in supplying heat, so that the problem of high energy efficiency in the membrane distillation process is solved, and the energy utilization efficiency of the desalination system can be improved;
(3) the preheater is used for recovering the waste heat of the strong brine, so that the preheater has good heat economy, and the adjusting valve is used for controlling the mixed salinity of the fresh water and the strong brine, so that the preheater has good water production flexibility.
(4) The energy storage unit of compressed gas is innovatively introduced, the preprocessing device 2 can provide stable power supply in all time according to actual operation needs, the problems of instability, discontinuity and the like during renewable energy acquisition are solved, the processes of dynamic operation, peak clipping and valley filling, frequency modulation and peak shaving and the like in renewable energy power generation can be assisted, and a controllable energy source with stability and high energy storage density is provided for power supply of a desalination system.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. A compressed gas energy storage type membrane distillation seawater desalination and desalination system is characterized by comprising a water taking pump (1), a seawater pretreatment unit, a membrane distillation unit, a heat collection unit, an energy obtaining unit and an energy storage unit;
the seawater pretreatment unit is used for purifying seawater;
the membrane distillation unit is used for desalting the purified seawater and comprises a heater (4), a membrane distillation assembly (5) and a fresh water collecting tank (7); wherein, a tube pass inlet of the heater (4) is communicated with a water outlet of the seawater pretreatment unit, a tube pass outlet of the heater (4) is communicated with an inlet of the membrane distillation component (5), and a shell pass outlet of the heater (4) is connected with the heat collection unit; a membrane front outlet of the membrane distillation component (5) is connected with the seawater pretreatment unit, a membrane rear outlet of the membrane distillation component (5) is respectively connected with a fresh water collecting tank (7) and an adjusting valve (6) through two branches, and the fresh water collecting tank (7) is used for collecting fresh water under different opening degrees of the adjusting valve (6);
the heat collection unit is used for collecting solar energy, converting the solar energy into heat energy and providing a heat source for the heater (4);
the energy obtaining unit is used for converting the obtained renewable energy into electric energy and supplying power to the water taking pump (1), the heat collecting unit and the energy storage unit;
the energy storage unit is used for storing the electric energy in the form of compressed gas, and when the energy obtaining unit is influenced by meteorological conditions to cause insufficient or unstable electric energy, the energy storage unit assists the energy obtaining unit to supply power.
2. The compressed gas energy storage type membrane distillation seawater desalination and desalination system according to claim 1, wherein the seawater pretreatment unit comprises a pretreatment device (2) and a preheater (3), a water inlet of the pretreatment device (2) is connected with the water taking pump (1), and a water outlet of the pretreatment device (2) is connected with the preheater (3); preheater (3) are including tube side and shell side, and the tube side water inlet of preheater (3) communicates with the delivery port of preprocessing equipment (2), and the tube side delivery port of preheater (3) communicates with the tube side water inlet of heater (4), and the shell side water inlet of preheater (3) communicates with the delivery port before the membrane of membrane distillation subassembly (5), and the shell side delivery port output strong brine of preheater (3).
3. The system for desalinating seawater by distilling and desalinating seawater according to the energy-storage type membrane of compressed gas in the claim 1, wherein the heat collecting unit comprises a solar heat collector (8), a circulating pump (9), a water tank (10) and an electric heater (11);
the water tank (10) is a separated water tank, a first water inlet and a first water outlet are formed in the top of the water tank (10), a second water inlet is formed in the bottom of the water tank (10), a second water outlet is formed in one side of the water tank (10), and a partition plate is arranged in the water tank (10) and used for partitioning the first water inlet, the first water outlet, the second water inlet and the second water outlet; a second water outlet of the water tank (10) is communicated with a water inlet of the circulating pump (9), a water outlet of the circulating pump (9) is communicated with a water inlet of the solar heat collector (8), and a water outlet of the solar heat collector (8) is connected with a first water inlet of the water tank (10); a first water outlet of the water tank (10) is communicated with a shell pass water inlet of the heater (4), and a shell pass water outlet of the heater (4) is communicated with a second water inlet of the water tank (10);
the electric heater (11) is electrically connected with the energy storage unit and/or the energy obtaining unit.
4. The compressed gas energy storage type membrane distillation seawater desalination and desalination system as claimed in claim 3, wherein the solar heat collector (8) is a flat plate type solar heat collector or a vacuum tube type solar heat collector.
5. The system for desalinating seawater by distilling and desalinating compressed gas according to claim 1, wherein the energy-obtaining unit adopts a photoelectric panel (12) and/or a wind generating set; the membrane distillation assembly (5) adopts one or more of a direct contact type membrane distillation assembly, an air gap type membrane distillation assembly and a vacuum type membrane distillation assembly, and the membrane distillation assembly (5) adopts a single-stage or multi-stage membrane assembly form.
6. The system for desalinating seawater by distilling and desalinating seawater according to the compressed gas energy storage type membrane of claim 1, wherein the energy storage unit adopts a compressed gas energy storage assembly (13); the number of stages of a compressor and a turbine expander of the compressed gas energy storage assembly (13) is adjustable, and an energy storage medium adopts air or carbon dioxide as compressed gas and is used for storing work energy to be converted.
7. The compressed gas energy storage type membrane distillation seawater desalination and desalination system as claimed in claim 1, wherein the fresh water collection tank (7) can be communicated with the strong brine outlet pipeline, and the desalted water with salinity meeting different process requirements can flow out by adjusting the water outlet ratio of the two outlets through the adjusting valve (6).
8. The process for desalinating seawater by using the compressed gas energy storage type membrane distillation seawater desalination and desalination system as claimed in any one of claims 1 to 7, characterized by comprising the following steps:
1) inputting the seawater to be treated into a seawater pretreatment unit, and purifying the seawater;
2) purified seawater enters a tube pass of the heater (4), and the seawater in the tube pass of the heater (4) is heated by a heat collection unit;
3) the heated seawater enters a membrane distillation assembly (5), and is separated by the membrane distillation assembly (5) to obtain condensed desalted water and preheated concentrated brine.
9. The process for desalinating seawater based on the compressed gas energy storage type membrane distillation seawater desalination and desalination system as claimed in claim 8, wherein in the step 2), the water in the heat collection unit is driven by the circulating pump (9), flows through the solar heat collector (8) for heating, flows into the heater (4) through the water tank (10) for heating the seawater on the tube pass side, and the temperature of the seawater rises after absorbing heat;
in the step 3), the preheated strong brine obtained by separation of the membrane distillation assembly (5) is discharged from the bottom of the membrane distillation assembly (5), enters the seawater pretreatment unit again to exchange heat with the input pretreated seawater, and meanwhile, the condensed desalted water and the preheated strong brine are mixed in proportion through the adjusting valve (6) and then enter the fresh water collecting tank (7) to obtain desalted water with required salinity.
10. The process for desalinating seawater based on the membrane distillation seawater desalination system with compressed gas energy storage according to claim 8, wherein when the electric energy of the energy-obtaining unit is insufficient or unstable, the compressed gas energy storage unit (13) converts the stored compression work into electric energy to be output, and replaces or assists the photovoltaic panel (12) and/or the wind power generator set in the energy-obtaining unit to supply power to the water taking pump (1), the circulating pump (9) and the electric heater (11).
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