CN109205736B - A heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle - Google Patents

Abstract

The invention discloses a heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle. The system includes: α type free-piston Stirling engine cold chamber, engine cooler, engine regenerator, engine Heater, α-type free piston Stirling engine hot chamber, free piston assembly, compression accumulator, two-position two-way solenoid valve, load accumulator, seawater desalination reverse osmosis membrane assembly; the engine cooler, engine The regenerator and engine heater are connected end to end. The system of the present invention realizes the reciprocating motion of the free piston assembly by using the Stirling cycle to do work, and with the cooperation of the compression accumulator, pushes the seawater in the pump chamber to overcome the osmotic pressure and enter the reverse osmosis membrane assembly for desalination.

Description

A heat-driven free-piston reverse osmosis seawater desalination power based on Stirling cycle system

technical field

The invention relates to the field of heat-driven reverse osmosis desalination, in particular to a heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle.

Background technique

Fresh water resources are an important material basis for human survival, economic development and social progress. Nowadays, due to the vigorous development of industry, the discharge of domestic sewage, the dumping of garbage, etc., water pollution is becoming more and more serious. Now most countries in the world are water-deficient countries, and there is a large amount of seawater on the earth. Desalination of seawater is an effective way to solve the shortage of freshwater resources in coastal areas. While alleviating the shortage of fresh water resources, seawater desalination has also brought new pressures on energy and the environment. With the increasingly tense energy and environmental issues, the energy required for seawater desalination will become the focus of research.

In the technical field of seawater desalination, the reverse osmosis method has been widely used in the world, and is currently listed as one of the three mainstream methods of seawater desalination along with multi-stage flash evaporation and multi-effect distillation. The principle of reverse osmosis is to push seawater through the polymer membrane with external energy to separate the salt and water in the solution. Although there is no phase change in this process, the inherent energy consumption of the process is less, and the hydraulic energy of concentrated seawater after desalination can also realize energy recovery, but the power source of reverse osmosis desalination is a high-pressure pump, and its working pressure generally increases with the increase of seawater salinity However, in order to maintain a high water production rate of the equipment, the high-pressure pump needs to provide additional driving force for the seawater to overcome the process resistance, and its working power consumption generally accounts for about 35% of the system energy consumption.

In 1816, Scottish Robert Stirling proposed a thermodynamic cycle consisting of two isothermal processes and two isovolumic processes, called the Stirling cycle. The Stirling cycle is a reversible cycle consisting of two constant-volume endothermic processes and two constant-temperature expansion processes, and the heat released by the constant-volume exothermic process is just absorbed by the constant-volume endothermic process. The heat engine absorbs heat from a high-temperature heat source during expansion at a constant temperature (T1), and releases heat to a low-temperature heat source during compression at a constant temperature (T2). This cycle is originally used in heat engines, where the working fluid in the system is continuously compressed and expanded at different temperature levels, and finally produces work.

The conventional reverse osmosis process is: raw water → pretreatment system → high pressure water pump → reverse osmosis membrane module → purified water. For the reverse osmosis desalination power system, it only needs to be able to push seawater through the reverse osmosis membrane against the osmotic pressure, and the form of pushing work can be either the shaft work of the rotary pump or the linear work of the reciprocating pump (such as the piston type).

As an externally heated piston-type power machine, the Stirling engine has strong adaptability to heat sources, and can utilize renewable energy such as solar energy and biomass energy, as well as industrial waste heat and exhaust gas. The free-piston engine developed on the basis of the traditional engine cancels the rigid body transmission mechanism such as the crank connecting rod, and uses the non-rigid medium as the receiver of the mechanical energy of the translation of the piston to maintain the periodicity of the movement.

Contents of the invention

The purpose of the present invention is to overcome the power problems existing in the current seawater desalination system, and provide a heat-driven free-piston reverse osmosis seawater desalination power system based on the Stirling cycle, which has the advantages of compact structure, high energy conversion efficiency, few components, and high power. High density, high energy utilization efficiency, high reliability, and the advantages of using clean energy; and low-grade heat sources can be used as heating heat sources, and the heat energy utilization efficiency is high. The heat-driven free-piston reverse osmosis seawater desalination power system based on the Stirling cycle provided by the present invention has broad development and application prospects in the field of heat-driven reverse osmosis desalination.

In order to achieve the above object, the present invention provides a heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle, said system comprising: α-type free-piston Stirling engine cold chamber (1), engine cooling (2), engine regenerator (3), engine heater (4), α-type free-piston Stirling engine hot chamber (5), free-piston assembly (6), compression accumulator (7), Two-position two-way solenoid valve (8), load accumulator (9), seawater desalination reverse osmosis membrane assembly (10); the engine cooler (2), engine regenerator (3), engine heater (4 )End to end.

As a new power system, the heat source absorbed by the engine heater (4) is rich, which can be chemical energy combustion, electric energy heating, nuclear energy, etc., and can also be new clean solar energy, geothermal energy, etc.

As a new type of power system, the gas working medium in the system is helium, argon, nitrogen, air or their mixed gases.

As a new power system, the engine adopts an α-type free-piston Stirling engine with a simple and compact structure.

As a new type of power system, the engine uses a compression accumulator (7) and a two-position two-way solenoid valve (8) to realize the operation of the Stirling engine.

As a new type of power system, the engine cooler (2) of the system is cooled by seawater, and the cooling water power comes from part of the output pressure of the Stirling engine.

As a novel power system, the load accumulator (9) of the system is connected with the seawater desalination reverse osmosis membrane assembly (10), which can provide stable output pressure.

A heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle of the present invention has the advantages of:

1. The heat source absorbed by the system of the present invention is relatively wide, and the heat source is relatively adaptable, and is applicable to various energy sources, such as solar energy, biofuel, industrial waste heat, nuclear energy, etc.;

2. The system of the present invention adopts environmentally friendly gas working fluids such as helium, argon, nitrogen, air or their mixed gases, which has no greenhouse effect and is environmentally friendly;

3. Compared with the structure of the traditional Stirling engine, the system of the present invention adopts the free-piston Stirling engine, which reduces the free-piston intermediate transmission parts in the engine, thereby reducing the mechanical vibration of the system and improving the system performance. Reliability and operating life, with higher power density, more compact structure and less material consumption;

4. The system of the present invention adopts the free piston reverse osmosis desalination power system, further simplifies the transmission chain, reduces energy conversion and transmission links, and is beneficial to improve energy utilization efficiency and reduce desalination energy costs;

5. The system of the present invention can effectively utilize clean energy to provide stable power and realize seawater desalination, and has significant energy saving and emission reduction effects and broad application prospects.

Description of drawings

Fig. 1 Schematic diagram of a heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle.

Reference signs:

1. α type free piston Stirling engine cold chamber

2. Engine cooler

3. Engine regenerator

4. Engine heater

5. α-type free-piston Stirling engine hot chamber

6. Free piston assembly

7. Compression accumulator

8. Two-position two-way solenoid valve

9. Load accumulator

10. Seawater desalination reverse osmosis membrane module

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the implementation of the present invention. example, not all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The invention efficiently utilizes various heat sources, has strong adaptability, adopts α-type free-piston Stirling engine, reduces the intermediate transmission part, can realize higher power density, compact structure, low cost of processing and reliable operation The stability is greatly improved, and it is easy to realize industrial production and practical application.

As shown in Fig. 1, the present invention is a heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle, said system comprising: α-type free-piston Stirling engine cold chamber (1), engine cooling (2), engine regenerator (3), engine heater (4), α-type free-piston Stirling engine hot chamber (5), free-piston assembly (6), compression accumulator (7), Two-position two-way solenoid valve (8), load accumulator (9), seawater desalination reverse osmosis membrane assembly (10); the engine cooler (2), engine regenerator (3), engine heater (4 )End to end.

The heat-driven free-piston reverse osmosis seawater desalination power system based on the Stirling cycle, when working, the gas working medium passes through the engine heater (4) to absorb heat from the heating heat source, and the working medium is in the engine thermal chamber (5) In the process of expansion, one of the free pistons (6) is pushed to move, and the seawater in the cavity at the other end of the compression piston is compressed, and part of the seawater enters the compression accumulator (7) through the one-way valve to store part of the energy; part of the seawater passes through the one-way The valve enters the engine cooler (2), and the last part of seawater enters the seawater desalination reverse osmosis membrane assembly (10) to provide pressure for the reverse osmosis membrane. When the free piston assembly (6) moves to the outer dead center, the speed is zero, at this time a two-position two-way solenoid valve (8) is turned on, and the seawater in the accumulator passes through the two-position two-way solenoid valve (8) Enter the piston cavity, push the piston to move toward the inner dead center, and the accumulator acts as the starting force of the engine return stroke.

The working fluid cools down in the engine cooler (2) through the engine regenerator (3) and performs work, so that a corresponding free piston assembly (6) moves to the left (as shown in Figure 1), compressing the seawater in the piston chamber to do work, and part of the seawater Enter the compression accumulator (7) through the one-way valve to store part of the energy; part of the seawater enters the engine cooler (2) through the one-way valve, and the last part of the seawater enters the seawater desalination reverse osmosis membrane module (10) to provide pressure for the reverse osmosis membrane . When the free piston (6) moves to the inner dead center, the speed is zero, at this time the two-position two-way solenoid valve (8) is turned on, and the seawater in the accumulator enters the piston through the two-position two-way solenoid valve (8) Cavity, pushing the piston to move outward to the dead center, and repeat the movement like this. Both the seawater desalination reverse osmosis membrane module (10) and the engine cooler (2) are connected in series with an accumulator to provide a stable pressure source for the seawater desalination reverse osmosis membrane module (10) and the engine cooler (2).

Finally, it should be noted that the above materials are only used to illustrate the technical solution of the present invention rather than limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent replacements to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all of them should be included in the scope of the present invention. within the scope of the claims.

Claims (6)

1. A heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle, is characterized in that, described system comprises: α type free-piston type Stirling engine cold cavity (1), engine cooler (2 ), engine regenerator (3), engine heater (4), α-type free-piston Stirling engine hot chamber (5), two free-piston assemblies (6), two compression accumulators (7) , three two-position two-way solenoid valves (8), load accumulators (9), seawater desalination reverse osmosis membrane components (10); the α-type free-piston Stirling engine cold chamber (1) and engine cooling The engine cooler (2) is connected with the engine regenerator (3), the engine regenerator (3) is connected with the engine heater (4), the engine heater (4) is connected with the α-type free piston type Stirling engine hot chamber (5) is connected, two free piston assemblies (6) are respectively connected with two two-position two-way solenoid valves (8), and the two two-position two-way solenoid valves (8) are respectively connected with two The two compression accumulators (7) are connected, and the other two-position two-way solenoid valve (8) is connected with the load accumulator (9), and the water outlets of the two free piston assemblies (6) pass through the check valve respectively. Connected with seawater desalination reverse osmosis membrane module (10); When working, the working medium absorbs heat from the heating heat source through the engine heater (4), and the working medium expands in the engine heat chamber (5) to do work, pushing one of the free piston assemblies (6) to move to the right, and compressing the piston in the cavity at the other end. Seawater, a part of seawater enters one of the compression accumulators (7) through the one-way valve to store part of the energy, a part of the seawater enters the engine cooler (2) through the one-way valve, and the last part of seawater enters into the seawater desalination reverse osmosis membrane module ( 10) provide pressure for the reverse osmosis membrane; when the free piston assembly (6) moves to the outer dead center, the speed is zero, and the two-position two-way solenoid valve ( 8) conduction, the seawater in the compressed accumulator (7) enters the piston chamber through the two-position two-way solenoid valve (8), and pushes the piston to move toward the inner dead center, and the compressed accumulator (7) ) acts as the starting force of the engine return stroke; The working medium is cooled by the engine regenerator (3) to perform work in the engine cooler (2), causing the other free piston assembly (6) to move to the left, compressing the seawater in the piston cavity to perform work, and part of the seawater enters through the one-way valve Another compression accumulator (7) stores part of the energy, a part of seawater enters the engine cooler (2) through the one-way valve, and the last part of seawater enters the described seawater desalination reverse osmosis membrane module (10) to provide pressure for the reverse osmosis membrane; When the free piston assembly (6) moves to the inner dead center, the speed is zero, at this time, the two-position two-way solenoid valve (8) connected to the free piston assembly (6) is turned on, and the compression accumulator The seawater in the energy device (7) enters the piston cavity through the two-position two-way solenoid valve (8), and pushes the piston to move outward to the dead center, so that the seawater desalination is realized through such repeated movements. 2. The heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle according to claim 1, is characterized in that, the heat source that described engine heater (4) absorbs is extensive, and heat source comprises solar energy, biological Fuel, industrial waste heat, nuclear energy. 3. The heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle according to claim 1, wherein the working medium is hydrogen, helium, argon, nitrogen, air or their mixture gas. 4. The heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle according to claim 1, characterized in that the engine cooler (2) is cooled by seawater, and its power comes from two free pistons Part of the seawater pressure energy generated by the reciprocating motion of the component (6). 5. The heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle according to claim 1, characterized in that, the piston chambers of the two free-piston assemblies (6) and the joints of the pipelines are all provided with There is a one-way valve. 6. The heat-driven free-piston reverse osmosis seawater desalination power system based on Stirling cycle according to claim 1, characterized in that the load accumulator (9) is connected to the seawater desalination reverse osmosis membrane module (10) .

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