Low-temperature waste heat power generation system based on liquid-liquid phase splitting

Abstract

The utility model discloses a low-temperature waste heat power generation system based on liquid-liquid phase splitting, which comprises an absorber, a phase splitter, a pressure reduction component, an evaporator, an expansion machine and a generator, and the absorber is provided with a cooling medium inlet and a cooling medium outlet; an absorption liquid outlet of the absorber is connected with a solution inlet of the phase splitter, an upper-layer solution outlet of the phase splitter is connected with the evaporator, a lower-layer solution outlet of the phase splitter is connected with the solution inlet of the absorber, a steam outlet of the evaporator is connected with a steam inlet of the expansion machine, and a steam outlet of the expansion machine is connected with a steam inlet of the absorber. The expansion machine is connected with the generator; working medium pairs used in the system are partially soluble working medium pairs, and a heat source inlet of the evaporator is communicated with a waste heat supply pipeline. According to the low-temperature waste heat power generation system based on liquid-liquid phase separation, separation of the light-phase solution and the heavy-phase solution is achieved through liquid-liquid phase separation, and compared with gas-liquid phase separation, use of heat is reduced, and the heat-work conversion efficiency of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of low-temperature waste heat power generation, and particularly relates to a low-temperature waste heat power generation system based on liquid-liquid phase separation. Background Art

[0002] There is a large amount of low-temperature waste heat in the industrial field, mainly in the forms of flue gas, low-temperature hot water or low-pressure exhaust gas. Due to its low energy level and grade, it cannot be directly recycled. This part of low-temperature waste heat is often discharged into the atmospheric environment through a cooling system, which not only causes a large amount of energy waste, but also indirectly leads to environmental pollution. The existing thermo-mechanical conversion power generation technologies mainly include: steam Rankine cycle, organic Rankine cycle and Kalina cycle.

[0003] The steam Rankine cycle uses low-temperature waste heat as the driving heat source and steam as the working fluid. Since the specific volume of steam at low temperature is relatively large, the flow channel interface and equipment volume of the expander are large, the isentropic efficiency of the expander is low, and the manufacturing and processing of the expander are difficult, resulting in high production costs.

[0004] The organic Rankine cycle is a Rankine cycle with a low-boiling organic substance as the working fluid, mainly composed of an evaporator, an expander, a condenser and a working fluid pump. Its working principle is as follows: the working fluid absorbs heat in the evaporator to generate steam with a certain pressure and temperature. The steam enters the expander to expand and do work, thereby driving the generator to generate electricity; the steam discharged from the expander releases heat to the cooling water in the condenser and condenses into a liquid state, and finally returns to the evaporator with the help of the working fluid pump, and so on continuously. The organic Rankine cycle overcomes the problem of the large flow channel interface and equipment volume of the expander in the steam Rankine cycle. However, the back pressure of the expander in the organic Rankine cycle is restricted by the condensation temperature of the condenser, and the relatively high back pressure of the expander restricts the improvement of the thermoelectric conversion efficiency of the organic Rankine cycle to a certain extent.

[0005] The Kalina cycle is a hybrid working fluid Rankine cycle with absorption coupling, which uses an ammonia-water binary mixture as the cycle working fluid. As Figure 1As shown in the figure, it mainly consists of a generator a, a condenser c, an evaporator 9, a rectifying device b, an expander 1, an absorber 2, and a working fluid pump. Its working principle is as follows: The ammonia-water solution is heated by a low-temperature heat source in the generator a. The ammonia water is heated to release ammonia gas and a small amount of water vapor. After being rectified and purified, it enters the condenser c and is condensed into liquid ammonia by cooling water. The liquid ammonia is pressurized and then enters the evaporator 9, where it is heated and evaporated by low-temperature waste heat to obtain high-pressure ammonia gas. The ammonia gas enters the expander 1 to expand and do work, thereby driving the generator to generate electricity. The dilute ammonia water at the outlet of the generator a returns to the absorber 2 with the help of the working fluid pump (in order to keep the absorber 2 at an appropriate temperature, a cooling tower d is set in the system to cool the absorber 2), where it absorbs the ammonia gas discharged from the expander 1, and so on in a cycle. Compared with the organic Rankine cycle, the strong absorption characteristic of water for ammonia in the Kalina cycle significantly reduces the back pressure of the expander 1. However, in order to obtain a higher inlet pressure of the expander 1, the Kalina cycle needs to use a rectifying device b, resulting in large heat source consumption and increased costs. In addition, ammonia has a strong pungent smell, is toxic, flammable, and explosive to the human body. When the heat source temperature is higher than 250 °C, there will also be a thermal decomposition problem of NH 3 in the Kalina cycle, causing environmental pollution. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a low-temperature waste heat power generation system based on liquid-liquid phase separation, which changes the traditional "gas-liquid" phase separation to "liquid-liquid" phase separation, reduces heat source consumption, and improves the thermal power conversion efficiency of the system.

[0007] In the first aspect of the present invention, a low-temperature waste heat power generation system based on liquid-liquid phase separation is provided, including an absorber, a phase separator, a pressure-reducing component, an evaporator, an expander, and a generator.

[0008] The absorber is provided with a cooling medium inlet and a cooling medium outlet for cooling the absorption liquid in the absorber.

[0009] The absorption liquid outlet of the absorber is connected to the solution inlet of the phase separator. The upper-layer solution outlet of the phase separator is connected to the evaporator through a pressure-reducing component. The lower-layer solution outlet of the phase separator is connected to the solution inlet of the absorber. The steam outlet of the evaporator is connected to the steam inlet of the expander. The steam outlet of the expander is connected to the steam inlet of the absorber. The expander is connected to the generator to drive the generator to generate electricity. The working fluid pair used in the system is a partially miscible working fluid pair. The heat source inlet of the evaporator is connected to the waste heat supply pipeline.

[0010] The connection here can be a direct connection, such as the lower-layer solution outlet of the phase separator is directly connected to the solution inlet of the absorber; it can also be an indirect connection, such as when a regenerator is added to the system, the lower-layer solution outlet of the phase separator enters the regenerator and flows into the solution inlet of the absorber through the regenerator outlet.

[0011] The absorber is provided with a cooling medium inlet and a cooling medium outlet. The cooling medium here is used to cool the absorption liquid in the absorber to prevent the temperature of the absorption liquid from being too high, which may affect the absorption of the steam discharged from the expander by the absorber and cause an increase in the back pressure of the expander.

[0012] As a preferred embodiment, a temperature regulating component is further provided between the absorber and the phase separator for regulating the temperature of the absorption liquid.

[0013] As a preferred embodiment, a first regenerator is provided between the phase separator and the evaporator. The upper solution outlet of the phase separator is connected to the first solution inlet of the first regenerator. The first solution outlet of the first regenerator is connected to the solution inlet of the evaporator. The solution outlet of the evaporator is connected to the second solution inlet of the first regenerator. The second solution outlet of the first regenerator is connected to the solution inlet of the absorber.

[0014] As a preferred embodiment, a first solution pump is provided between the first regenerator and the evaporator. The solution outlet of the evaporator is connected to the second solution inlet of the first regenerator through the first solution pump.

[0015] As a preferred embodiment, a first regenerator is provided between the phase separator and the evaporator. The upper solution outlet of the phase separator is connected to the first solution inlet of the first regenerator. The first solution outlet of the first regenerator is connected to the solution inlet of the evaporator. The solution outlet of the evaporator is connected to the second solution inlet of the first regenerator. The second solution outlet of the first regenerator is connected to the solution inlet of the temperature regulating component.

[0016] As a preferred embodiment, a first throttle valve is provided between the first regenerator and the evaporator. The solution outlet of the evaporator is connected to the second solution inlet of the first regenerator through the first throttle valve.

[0017] As a preferred embodiment, a second solution pump is provided between the absorber and the phase separator for transporting the absorption liquid in the absorber to the phase separator.

[0018] As a preferred embodiment, a second throttle valve is provided between the phase separator and the absorber. The lower solution outlet of the phase separator is connected to the solution inlet of the second throttle valve. The solution outlet of the second throttle valve is connected to the solution inlet of the absorber.

[0019] As a preferred embodiment, a second regenerator is provided between the absorber and the temperature regulating component. The absorption liquid outlet of the absorber is connected to the first solution inlet of the second regenerator. The first solution outlet of the second regenerator is connected to the temperature regulating component. The lower solution outlet of the phase separator is connected to the second solution inlet of the second regenerator. The second solution outlet of the second regenerator is connected to the solution inlet of the absorber.

[0020] As a preferred embodiment, a third regenerator is provided between the absorber and the expander. The steam outlet of the expander is connected to the first solution inlet of the third regenerator. The first solution outlet of the third regenerator is connected to the steam inlet of the absorber. The absorbent liquid outlet of the absorber is connected to the second solution inlet of the third regenerator. The second solution outlet of the third regenerator is connected to the phase separator.

[0021] As a preferred embodiment, a third regenerator is provided between the absorber and the expander. The steam outlet of the expander is connected to the first solution inlet of the third regenerator. The first solution outlet of the third regenerator is connected to the steam inlet of the absorber. The absorbent liquid outlet of the absorber is connected to the second solution inlet of the third regenerator. The second solution outlet of the third regenerator is connected to the temperature regulating component.

[0022] As a preferred embodiment, the pressure reducing component is selected from throttle valves.

[0023] As a preferred embodiment, the working fluid pair is a binary or ternary partially miscible working fluid pair.

[0024] As a more preferred embodiment, the working fluid pair is a working fluid pair with the highest consolute temperature or the lowest consolute temperature.

[0025] As a more preferred embodiment, the working fluid pair is selected from any one of water - phenol, water - isobutanol, water - aniline, nitrobenzene - n - hexane, Freon - refrigeration oil, water - ionic liquid, water - triethylamine, n - hexane - diethylene glycol - benzene, ethanol - water - vinyl cyanide, ether - water - vinyl cyanide.

[0026] Compared with the prior art, the utility model has the following beneficial effects:

[0027] (1) The low - temperature waste heat power generation system of the utility model based on liquid - liquid phase separation realizes the separation of the light - phase solution and the heavy - phase solution through "liquid - liquid" phase separation. Compared with "gas - liquid" phase separation, it reduces the use of heat and improves the thermal - power conversion efficiency of the system.

[0028] (2) In the low - temperature waste heat power generation system of the utility model based on liquid - liquid phase separation, the generator and the condenser are not essential components, reducing the use of components and lowering the use and installation costs.

[0029] (3) In the low - temperature waste heat power generation system of the utility model based on liquid - liquid phase separation, the solution for evaporation is a light - phase - rich solution rather than a pure light - phase solution. The system does not require a rectification device, significantly reducing the external dimensions of the system equipment and facilitating the integration of the system equipment.

[0030] (4) The low-temperature waste heat power generation system of the present utility model based on liquid-liquid phase separation. The heavy-phase solution obtained by the phase separator enters the absorber to absorb the light-phase steam at the outlet of the expander. Since the absorber uses a cooling medium for temperature reduction and the internal temperature of the absorber is within a suitable range, the light-phase solution can be quickly dissolved in the heavy-phase solution, the absorption pressure decreases, and the back pressure of the expander drops, ensuring that the system has a high thermal power conversion efficiency.

[0031] The concept, specific structure and technical effects of the present utility model will be further described below in conjunction with the accompanying drawings to fully understand the purpose, features and effects of the present utility model. Brief Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of a low-temperature waste heat power generation system based on the Kalina cycle;

[0033] Figure 2 is a schematic structural diagram of the low-temperature waste heat power generation system based on liquid-liquid phase separation in Embodiment 1 of the present utility model;

[0034] Figure 3 is a schematic structural diagram of the low-temperature waste heat power generation system based on liquid-liquid phase separation in Embodiment 2 of the present utility model;

[0035] Figure 4 is a schematic structural diagram of the low-temperature waste heat power generation system based on liquid-liquid phase separation in Embodiment 3 of the present utility model;

[0036] Figure 5 is a schematic structural diagram of the low-temperature waste heat power generation system based on liquid-liquid phase separation in Embodiment 4 of the present utility model.

[0037] Wherein: a - generator, b - rectifying device, c - condenser, d - cooling tower, 1 - expander, 2 - absorber, 3 - temperature regulating component, 4 - second throttle valve, 5 - phase separator, 6 - pressure reducing component, 7 - first regenerator, 8 - first solution pump, 9 - evaporator, 10 - generator, 11 - second solution pump, 12 - first throttle valve, 13 - second regenerator, 14 - third regenerator. Detailed Embodiments

[0038] In order to make the technical means, creative features, achieved purposes and effects of the utility model easy to understand, the present utility model will be further described below in conjunction with specific illustrations. However, the present utility model is not limited to the following implemented cases.

[0039] It should be noted that the structures, proportions, sizes, etc. shown in the drawings of this specification are only used to match the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the implementation conditions of the present utility model. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the efficacy that the present utility model can produce and the purpose that can be achieved, should still fall within the scope covered by the technical content disclosed by the present utility model.

[0040] There is a large amount of low-temperature waste heat in the industrial field. If directly discharged, it will not only cause a large waste of energy but also lead to environmental pollution. The steam Rankine cycle, organic Rankine cycle, and Kalina cycle are currently relatively commonly used low-temperature waste heat power generation technologies. However, in the steam Rankine cycle, the flow channel interface and equipment volume of the expander are both large, and the manufacturing cost is relatively high. In the organic Rankine cycle, the back pressure of the expander is relatively large, which limits the thermoelectric conversion efficiency. The Kalina cycle solves the back pressure problem of the expander based on the "gas-liquid" phase separation-absorption cycle. However, due to the need to use a generator, condenser, and rectification equipment for the "gas-liquid" phase separation, the energy consumption increases and the production cost increases.

[0041] This application changes the existing idea and transforms the "gas-liquid" phase separation-absorption-"gas-liquid" phase separation cycle in the Kalina cycle into a "liquid-liquid" phase separation-absorption-"liquid-liquid" phase separation, avoiding the use of generators and rectification equipment, with small heat source consumption and high thermal power conversion efficiency.

[0042] The absorbent solution mentioned below is a mixed solution obtained after the absorbent absorbs the refrigerant, which can be a completely homogeneous liquid phase or a multiphase with partial stratification. Taking the ammonia-water working medium pair as an example, where ammonia is the refrigerant and water is the absorbent, the formed ammonia water is the absorbent solution.

[0043] The present utility model provides a low-temperature waste heat power generation system based on liquid-liquid phase separation, including an absorber 2, a phase separator 5, a pressure reduction component 6, an evaporator 9, an expander 1, and a generator 10. The absorber 2 is provided with a cooling medium inlet and a cooling medium outlet for cooling the absorbent solution in the absorber 2; the absorbent solution outlet of the absorber 2 is connected to the solution inlet of the phase separator 5. The upper layer solution outlet of the phase separator 5 is connected to the evaporator 9 through the pressure reduction component 6. The lower layer solution outlet of the phase separator 5 is connected to the solution inlet of the absorber 2. The steam outlet of the evaporator 9 is connected to the steam inlet of the expander 1. The steam outlet of the expander 1 is connected to the steam inlet of the absorber 2. The expander 1 is connected to the generator 10 for driving the generator 10 to generate electricity; the working medium pair used in the system is a partially miscible working medium pair, and the heat source inlet of the evaporator 9 is connected to the waste heat supply pipeline.

[0044] Absorber 2 provides a place for the absorbent to absorb the refrigerant. In the absorber 2, the absorbent absorbs the refrigerant vapor and releases a large amount of heat. The absorber 2 releases the heat to the environment through circulating water. The absorber 2 involved in this application can be a falling film absorber or an absorption tower. The falling film absorber can adopt a plate falling film absorber, a horizontal tube falling film absorber or a vertical tube falling film absorber. The absorber is not limited to this, and any device with similar functions can be used in this application.

[0045] Since the refrigerant vapor has a certain temperature and the absorbent releases a certain amount of heat during the absorption of the refrigerant, the temperature of the absorption liquid in the absorber 2 increases. In order to avoid the influence of the too high temperature of the absorber 2 on the back pressure of the expander 1, the absorber 2 is provided with a cooling medium inlet and a cooling medium outlet to cool the absorption liquid.

[0046] The phase separator 5 provides a place for liquid-liquid phase separation. The upper layer solution in the phase separator 5 is a light component solution, which is also a refrigerant-rich solution, and the absorbent is dissolved in the refrigerant; the lower layer solution is a heavy component solution, which is also an absorbent-rich solution, and the refrigerant is dissolved in the absorbent.

[0047] The evaporator 9 can convert a liquid substance into a gaseous substance. The evaporator 9 in this application can adopt a kettle-type full liquid evaporator or a falling film evaporator. The evaporator 9 is not limited to this, and any device with similar functions can be used in this application.

[0048] The absorption liquid flowing out of the absorber 2 is a mixture of the absorbent and the refrigerant. Due to the use of the cooling medium to control the temperature of the absorber 2, the absorption liquid entering the phase separator 5 shows liquid-liquid stratification. The solution located in the upper layer of the phase separator 5 enters the evaporator 9 after being depressurized by the pressure reducing component 6. At this time, the evaporator 9 uses the recovered heat (such as 80 °C) for the heating process. The steam generated by the evaporator 9 enters the expander 1 to do work and drives the generator 10 to generate electricity. The solution located in the lower layer of the phase separator 5 returns to the absorber 2 again, and the absorbent absorbs the steam to obtain the absorption liquid for subsequent circulation.

[0049] This application realizes the separation of the refrigerant and the absorbent through liquid-liquid phase separation, without the need to use additional heat sources, reduces the use of heat, and reduces energy consumption; at the same time, it reduces the installation of some equipment, significantly reduces the external dimensions of the system equipment, and is convenient for system equipment integration.

[0050] As a preferred embodiment, a temperature regulating component 3 is further arranged between the absorber 2 and the phase separator 5 to regulate the temperature of the absorption liquid.

[0051] For the working fluid pair with the highest consolute point, in order to ensure that the absorbent in the absorber 2 has an excellent absorption effect on the refrigerant vapor discharged from the expander 1, the absorption pressure is reduced to the lowest to improve the thermal power conversion efficiency. The temperature inside the absorber 2 is adjusted by a cooling medium so that the absorbent and the refrigerant are in a completely miscible state, facilitating the absorption of the refrigerant. After the absorption process is completed, the circulation speed of the cooling medium is adjusted to lower the temperature inside the absorber 2, causing the absorbent and the refrigerant to separate into layers, achieving liquid-liquid phase separation. Of course, it is also possible not to adjust the circulation speed of the cooling medium and use the temperature adjustment component 3 for cooling.

[0052] For the working fluid pair with the lowest consolute point, when the absorbent and the refrigerant are at a relatively low temperature, they are in a completely miscible state. After the absorption process is completed, in order to achieve the effect of liquid-liquid phase separation, the temperature is increased by the temperature adjustment component 3.

[0053] The temperature adjustment component 3 can adopt a shell-and-tube cooler, a plate cooler, and an air-cooled cooler. The temperature adjustment component 3 is not limited to this, and any device with a similar function can be used in this application.

[0054] Wherein, a first regenerator 7 is arranged between the phase separator 5 and the evaporator 9. The upper solution outlet of the phase separator 5 is connected to the first solution inlet of the first regenerator 7. The first solution outlet of the first regenerator 7 is connected to the solution inlet of the evaporator 9. The solution outlet of the evaporator 9 is connected to the second solution inlet of the first regenerator 7. The second solution outlet of the first regenerator 7 is connected to the solution inlet of the absorber 2.

[0055] The first regenerator 7 is provided to realize the reuse of heat and save energy. Since the solution that is not evaporated in the evaporator 9 has a certain temperature, this part of the heat is used to heat the solution entering the evaporator 9 from the phase separator 5, reducing the heat consumption of the evaporator 9. The solution that is not evaporated in the evaporator 9 is cooled and then incorporated into the lower-layer solution of the phase separator 5 and returns to the absorber 2 to absorb the refrigerant vapor flowing out of the expander 1. In addition, the solution that is not evaporated in the evaporator 9 is cooled by the first regenerator 7, which to a certain extent reduces the use of the cooling medium in the absorber 2.

[0056] Wherein, a first solution pump 8 is arranged between the first regenerator 7 and the evaporator 9. The solution outlet of the evaporator 9 is connected to the second solution inlet of the first regenerator 7 through the first solution pump 8.

[0057] Wherein, a first regenerator 7 is arranged between the phase separator 5 and the evaporator 9. The upper solution outlet of the phase separator 5 is connected to the first solution inlet of the first regenerator 7. The first solution outlet of the first regenerator 7 is connected to the solution inlet of the evaporator 9. The solution outlet of the evaporator 9 is connected to the second solution inlet of the first regenerator 7. The second solution outlet of the first regenerator 7 is connected to the solution inlet of the temperature adjustment component 3.

[0058] In addition to directly flowing back to the absorber 2, the solution that has not been evaporated by the evaporator 9 can also be added to the temperature regulating component 3 for temperature regulation and then enter the phase separator 5 to concentrate the absorption liquid, and the concentrated absorption liquid flows back to the absorber 2 again.

[0059] Among them, a first throttle valve 12 is arranged between the first regenerator 7 and the evaporator 9, and the solution outlet of the evaporator 9 is connected to the second solution inlet of the first regenerator 7 through the first throttle valve 12.

[0060] Among them, a second solution pump 11 is arranged between the absorber 2 and the phase separator 5 for transporting the absorption liquid in the absorber 2 to the phase separator 5.

[0061] Among them, a second throttle valve 4 is arranged between the phase separator 5 and the absorber 2. The lower layer solution outlet of the phase separator 5 is connected to the solution inlet of the second throttle valve 4, and the solution outlet of the second throttle valve 4 is connected to the solution inlet of the absorber 2.

[0062] As a preferred embodiment, a second regenerator 13 is arranged between the absorber 2 and the temperature regulating component 3. The absorption liquid outlet of the absorber 2 is connected to the first solution inlet of the second regenerator 13, the first solution outlet of the second regenerator 13 is connected to the temperature regulating component 3, the lower layer solution outlet of the phase separator 5 is connected to the second solution inlet of the second regenerator 13, and the second solution outlet of the second regenerator 13 is connected to the solution inlet of the absorber 2.

[0063] Since the lower layer solution of the phase separator 5 is the solution processed by the temperature regulating component 3, when the temperature regulating component 3 heats up the absorption liquid flowing out of the absorber 2 (for the working fluid pair with the lowest consolute point), the lower layer solution of the phase separator 5 usually has a certain temperature. Recycling the heat carried by the lower layer solution of the phase separator 5 to preheat the absorption liquid that has not yet entered the temperature regulating component 3 can reduce the use of heat by the temperature regulating component 3; when the temperature regulating component 3 cools down the absorption liquid flowing out of the absorber 2 (for the working fluid pair with the highest consolute point), the temperature of the lower layer solution of the phase separator 5 is relatively low. Using the lower layer solution of the phase separator 5 to precool the absorption liquid that has not yet entered the temperature regulating component 3 can reduce the use of the cooling medium by the temperature regulating component 3. At the same time, the temperature of the lower layer solution of the phase separator 5 increases to a certain extent, which is also conducive to the complete miscibility of the absorbent and the refrigerant in the absorber.

[0064] As a preferred embodiment, a third regenerator 14 is arranged between the absorber 2 and the expander 1. The steam outlet of the expander 1 is connected to the first solution inlet of the third regenerator 14, the first solution outlet of the third regenerator 14 is connected to the steam inlet of the absorber 2, the absorption liquid outlet of the absorber 2 is connected to the second solution inlet of the third regenerator 14, and the second solution outlet of the third regenerator 14 is connected to the phase separator 5.

[0065] Since the refrigerant vapor discharged from the expander 1 has a certain temperature, in order to reduce the use of cooling water in the absorber 2, a third regenerator 14 is provided between the absorber 2 and the expander 1. The third regenerator 14 cools the refrigerant vapor discharged from the expander 1. At the same time, the absorbent liquid flowing out of the absorber 2 enters the third regenerator 14 for temperature increase treatment to obtain the temperature range required for liquid-liquid phase separation. The reuse of heat here is applicable to the working fluid pair with the lowest consolute point. The setting of the third regenerator 14 can replace the use of the temperature regulating component 3.

[0066] Among them, the pressure reducing component 6 is selected from a throttle valve.

[0067] The setting of the pressure reducing component 6 reduces the pressure of the solution entering the evaporator 9 from the phase separator 5, facilitates the generation of steam, and improves the efficiency of the subsequent absorption process.

[0068] A binary mixed solution refers to a solution containing two components, such as the mixture of ammonia and water; a ternary mixed solution refers to a solution containing three components, such as the mixture of n-hexane, diethylene glycol, and benzene. A multi-component mixed solution is a mixed solution containing more than three components.

[0069] For binary, ternary, or multi-component mixed solutions, according to the solubility differences between the solutions, the solution types can be divided into three categories: completely miscible type, partially miscible type, and completely immiscible type. Among them, a completely miscible type solution can dissolve each other in any proportion to form a homogeneous liquid phase, and there is no interface in the mixed liquid. A completely immiscible type solution has large differences in properties between substances and does not dissolve each other, and an obvious interface appears in the system. A partially miscible type solution is between a completely miscible type solution and a completely immiscible type solution, which means that the solubility between substances changes with temperature and is not always in a completely miscible or completely immiscible state.

[0070] For a partially miscible type solution, the concentration of a single component cannot be too high or too low. If the concentration of a single component is too high, such as 99% by concentration ratio, then because the concentration of the other component is too low, the system always presents a completely miscible state instead of a partially miscible state. At this time, the solubility between each other does not change with temperature. The partially miscible type solution involved in this application means that the dissolution state between each other can change with temperature, and the situation where the single component concentration is too high or too low and leads to conversion into a completely miscible type solution is not within the scope of consideration of this application.

[0071] Partially miscible solutions can be further divided into three categories according to the variation law of their solubility with temperature: those with the highest consolute temperature type, those with the lowest consolute temperature type, and those with both the highest and lowest consolute temperature types. Among them, for the partially miscible solution with the highest consolute temperature, its mutual solubility decreases with the decrease of temperature. The higher the temperature, the closer the composition of the conjugate solution. When the temperature is higher than the highest consolute temperature, it is completely miscible. Therefore, for the solution with the highest consolute temperature, the temperature can be reduced below the highest consolute temperature, and the crude separation of binary, ternary or even multi-component solutions can be achieved through liquid-liquid phase separation. For the partially miscible solution with the lowest consolute temperature, its mutual solubility decreases with the increase of temperature. The lower the temperature, the closer the composition of the conjugate solution. When the temperature is lower than the lowest consolute temperature, the liquid phases are completely miscible. Therefore, for the binary, ternary or even multi-component solution with the lowest consolute temperature, the temperature can be increased above the lowest consolute temperature, and the separation of liquid-liquid phases can be achieved through liquid-liquid phase separation.

[0072] The working fluid pairs used in this system are partially miscible working fluid pairs, which can be binary partially miscible working fluid pairs, ternary partially miscible working fluid pairs, or multi-component partially miscible working fluid pairs. The mutual solubility of the working fluid pairs changes with temperature. For the convenience of selection, the working fluid pairs used in this system are all those with the highest consolute temperature or the lowest consolute temperature.

[0073] The working fluid pairs selected in this application, for binary partial miscibility, such as water - phenol, water - isobutanol, water - aniline, nitrobenzene - n - hexane, Freon - refrigeration oil, water - ionic liquid, water - triethylamine; for ternary partial miscibility, such as n - hexane - diethylene glycol - benzene, ethanol - water - vinyl cyanide, ether - water - vinyl cyanide.

[0074] The working process of the low - temperature waste heat power generation system based on liquid - liquid phase separation in this application is as follows:

[0075] A binary or multi-component solution with partial miscibility is temperature-regulated in absorber 2 with a cooling medium or in absorber 2 and temperature-regulating component 3. When the system uses a working fluid pair with the highest consolute temperature or the lowest consolute temperature, the combined action of absorber 2 or absorber 2 and temperature-regulating component 3 reduces the temperature below the highest consolute temperature or above the lowest consolute temperature; that is, the temperature of the working fluid pair solution is controlled to be in the partial miscibility temperature range through the combined action of absorber 2 or absorber 2 and temperature-regulating component 3, and then enters the phase separator 5 to achieve solution stratification; the resulting conjugate solutions are respectively the saturated solution of the absorbent dissolved in the refrigerant and the saturated solution of the refrigerant dissolved in the absorbent; the stratified solution rich in refrigerant is depressurized and then transported to the evaporator 9, and the refrigerant is vaporized by heating with a low-temperature heat source; the refrigerant vapor enters the expander 1 to expand and do work, driving the generator 10 to generate electricity; the unevaporated solution in the evaporator 9 and the stratified liquid rich in absorbent discharged from the phase separator 5 enter the absorber 2 to absorb the refrigerant vapor, the absorption pressure decreases, the back pressure of the expander 1 decreases, and the system thermal power conversion efficiency increases.

[0076] Taking the working fluid pair water-triethylamine with the lowest consolute temperature as an example, the system is driven by two low-temperature heat sources. One low-temperature heat source has a temperature of 60 °C and is used to heat the working fluid pair in the temperature-regulating component 3; the other low-temperature heat source is 105 °C and is used to heat and evaporate the light-phase solution in the evaporator 9; an aqueous solution of triethylamine with a mass concentration of 50% is introduced into the temperature-regulating component 3 and heated to 55 °C by 60 °C waste heat, and then enters the phase separator 5 for phase separation. After stratification, the mass concentration of triethylamine in the rich light phase is 97.8%, and the mass concentration of triethylamine in the rich heavy phase is 2%; the rich light-phase solution obtained from the phase separator 5 is heated to 76.7 °C after passing through the first regenerator 7, and then enters the evaporator 9 and is partially vaporized by heating with a 105 °C waste heat source. The evaporation temperature is 100 °C. The mass concentration of triethylamine in the steam obtained from the evaporator 9 is 90%, and the pressure is 2.2 bar. The steam drives the expander 1 to generate electricity; the exhaust steam at the outlet of the expander 1 enters the absorber 2 and is absorbed by the rich heavy-phase solution from the phase separator 5. The absorption heat is released to the environment by cooling water, and the temperature of the absorption completion liquid is 40 °C. The absorption pressure (i.e., the back pressure of the expander) is 0.19 bar, and the expansion ratio of the expander 1 is 11.6. The absorption completion liquid and the unevaporated solution in the evaporator 9 return to the temperature-regulating component 3 again and start the next cycle.

[0077] When using a working fluid pair with the highest consolute temperature, only one low-temperature heat source at 105 °C is required, which is used to heat the light-phase solution in the evaporator 9. At this time, the temperature-regulating component 3 is cooled by cooling water, and the others are similar to the above and will not be elaborated here.

[0078] Example 1

[0079] As Figure 2, A low-temperature waste heat power generation system based on liquid-liquid phase separation, comprising an expander 1, an absorber 2, a temperature regulating component 3, a second throttle valve 4, a phase separator 5, a pressure reducing component 6, a first regenerator 7, a first solution pump 8, an evaporator 9, a generator 10 and a second solution pump 11.

[0080] The absorber 2 is provided with a steam inlet, a solution inlet, an absorbent liquid outlet, a cooling medium inlet and a cooling medium outlet; the temperature regulating component 3 is provided with a solution inlet, a solution outlet, a heating medium inlet, a heating medium outlet or a cooling medium inlet, a cooling medium outlet; the phase separator 5 is provided with a solution inlet, an upper layer solution (light phase solution or low boiling point solution) outlet, a lower layer solution (heavy phase solution or high boiling point solution) outlet; the first regenerator 7 is provided with a first solution inlet, a first solution outlet, a second solution inlet, a second solution outlet; the evaporator 9 is provided with a solution inlet, a solution outlet, a steam outlet, a heating medium inlet and a heating medium outlet.

[0081] The steam outlet of the expander 1 is connected to the steam inlet of the absorber 2, the solution inlet of the absorber 2 is connected to the heavy phase solution outlet of the phase separator 5, and the second throttle valve 4 is installed on the connecting pipeline. The absorbent liquid outlet of the absorber 2 is connected to the inlet of the second solution pump 11, and the outlet of the second solution pump 11 is connected to the solution inlet of the temperature regulating component 3; the solution outlet of the temperature regulating component 3 is connected to the solution inlet of the phase separator 5; the light phase solution outlet of the phase separator 5 is connected to the first solution inlet of the first regenerator 7, and the pressure reducing component 6 is installed on the connecting pipeline. Here, the pressure reducing component 6 can be selected from a throttle valve; the first solution outlet of the first regenerator 7 is connected to the solution inlet of the evaporator 9; the solution outlet of the evaporator 9 is connected to the inlet of the first solution pump 8, and the steam outlet of the evaporator 9 is connected to the steam inlet of the expander; the expander is connected to the generator 10; the outlet of the first solution pump 8 is connected to the second solution inlet of the first regenerator 7, and the second solution outlet of the first regenerator 7 is connected to the solution inlet of the temperature regulating component 3.

[0082] The cooling medium inlet and the cooling medium outlet of the absorber 2 are respectively connected to cooling water; the heating medium inlet and the heating medium outlet of the evaporator 9 are respectively connected to a low-temperature waste heat supply pipeline. If the temperature regulating component 3 is used for heating up, the heating medium inlet and the heating medium outlet of the temperature regulating component 3 are respectively connected to the low-temperature waste heat supply pipeline; if the temperature regulating component 3 is used for cooling down, the cooling medium inlet and the cooling medium outlet of the temperature regulating component 3 are respectively connected to cooling water.

[0083] The working method of this embodiment is as follows:

[0084] When the system uses a partially miscible mixed working fluid pair with the lowest consolute temperature, the temperature of the absorption liquid discharged from the absorber 2 is relatively low. The mixed solution is heated to the temperature range of liquid-liquid phase separation by the temperature adjustment component 3, and then enters the phase separator 5 for phase separation. The obtained rich light-phase solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the rich light-phase solution partially evaporates, and the obtained high-pressure steam enters the expander 1 for power generation; the high-temperature solution that has not evaporated in the evaporator 9 is pressurized by the first solution pump 8 and then heats the rich light-phase solution entering the evaporator 9 from the phase separator 5 through the first regenerator 7, and then enters the temperature adjustment component 3 for further temperature adjustment and phase separation; the rich heavy-phase solution of the phase separator 5 enters the absorber 2 after throttling and pressure reduction to absorb the rich light-phase steam from the outlet of the expander 1; the absorption liquid of the absorber 2 is pressurized by the second solution pump 11 and then enters the temperature adjustment component 3 for temperature adjustment and is phase-separated again by the phase separator 5. During the operation of the system, the absorber 2 is cooled by circulating water; the evaporator 9 and the temperature adjustment component 3 are heated by low-temperature waste heat.

[0085] When the system uses a partially miscible mixed working fluid pair with the highest consolute temperature, the temperature of the absorption liquid discharged from the absorber 2 is relatively high. The mixed solution is cooled to the temperature range of liquid-liquid phase separation by the temperature adjustment component 3, and then enters the phase separator 5 for phase separation. The obtained rich light-phase solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the rich light-phase solution partially evaporates, and the obtained high-pressure steam enters the expander 1 for power generation; the high-temperature solution that has not evaporated in the evaporator 9 is pressurized by the first solution pump 8 and then heats the rich light-phase solution entering the evaporator 9 from the phase separator 5 through the first regenerator 7, and then enters the temperature adjustment component 3 for further temperature adjustment and phase separation; the rich heavy-phase solution of the phase separator 5 enters the absorber 2 after throttling and pressure reduction to absorb the rich light-phase steam from the outlet of the expander 1; the absorption liquid of the absorber 2 is pressurized by the second solution pump 11 and then enters the temperature adjustment component 3 for temperature adjustment and is phase-separated again by the phase separator 5. During the operation of the system, the absorber 2 and the temperature adjustment component 3 are cooled by circulating water; the evaporator 9 is heated by low-temperature waste heat. Of course, the temperature adjustment component 3 here is not a necessary component. When the outlet temperature of the absorption liquid of the absorber 2 is controlled by adjusting the flow rate of the circulating water so that the absorption liquid is in the temperature range of liquid-liquid phase separation, the temperature adjustment component 3 does not need to be used at this time, and it directly enters the phase separator 5 for phase separation.

[0086] When the temperature adjustment component 3 is used, the first regenerator 7 is also not a necessary component. The high-temperature solution that has not evaporated in the evaporator 9 enters the phase separator 5 after temperature adjustment by the temperature adjustment component 3 to concentrate the absorption liquid and improve the absorption efficiency.

[0087] Example 2

[0088] The difference from Example 1 is that in this example, the unevaporated solution in the evaporator 9 does not return to the temperature adjustment component 3 for temperature adjustment and then enter the phase separator 5, but directly enters the absorber 2.

[0089] Such asFigure 3 , a low-temperature waste heat power generation system based on liquid-liquid phase separation, comprising an expander 1, an absorber 2, a temperature regulating component 3, a second throttle valve 4, a phase separator 5, a pressure reducing component 6, a first recuperator 7, an evaporator 9, a generator 10, a second solution pump 11 and a first throttle valve 12.

[0090] The absorber 2 is provided with a steam inlet, a solution inlet, an absorption liquid outlet, a cooling medium inlet and a cooling medium outlet; the temperature regulating component 3 is provided with a solution inlet, a solution outlet, a heating medium inlet, a heating medium outlet or a cooling medium inlet and a cooling medium outlet; the phase separator 5 is provided with a solution inlet, an upper layer solution (light phase solution or low boiling point solution) outlet and a lower layer solution (heavy phase solution or high boiling point solution) outlet; the first recuperator 7 is provided with a first solution inlet, a first solution outlet, a second solution inlet and a second solution outlet; the evaporator 9 is provided with a solution inlet, a solution outlet, a steam outlet, a heating medium inlet and a heating medium outlet.

[0091] The steam outlet of the expander 1 is connected to the steam inlet of the absorber, the solution inlet of the absorber 2 is connected to the heavy phase solution outlet of the phase separator 5, and the second throttle valve 4 is installed on the connecting pipeline. The absorption liquid outlet of the absorber 2 is connected to the inlet of the second solution pump 11, and the outlet of the second solution pump 11 is connected to the solution inlet of the temperature regulating component 3; the solution outlet of the temperature regulating component 3 is connected to the solution inlet of the phase separator 5; the light phase solution outlet of the phase separator 5 is connected to the first solution inlet of the first recuperator 7, and the pressure reducing component 6 is installed on the connecting pipeline. Here, the pressure reducing component 6 is a throttle valve; the first solution outlet of the first recuperator 7 is connected to the solution inlet of the evaporator 9; the steam outlet of the evaporator 9 is connected to the steam inlet of the expander 1; the expander 1 is connected to the generator 10; the solution outlet of the evaporator 9 is connected to the second solution inlet of the first recuperator 7, and the first throttle valve 12 is installed on the connecting pipeline; the second solution outlet of the first recuperator 7 is connected to the solution inlet of the absorber 2.

[0092] The cooling medium inlet and the cooling medium outlet of the absorber 2 are respectively connected to cooling water; the heating medium inlet and the heating medium outlet of the evaporator 9 are respectively connected to a low-temperature waste heat supply pipeline.

[0093] The working method of this embodiment is as follows:

[0094] When the system uses a partially miscible mixed working fluid pair with the lowest consolute temperature, the temperature of the absorption liquid discharged from the absorber 2 is relatively low. The temperature of the mixed solution is adjusted to the temperature range of liquid-liquid phase separation through the temperature adjustment component 3, and then it enters the phase separator 5 for phase separation. The obtained rich light-phase solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the rich light-phase solution partially evaporates, and the obtained high-pressure steam enters the expander 1 for power generation; the high-temperature solution that has not evaporated in the evaporator 9 is pressurized by the first throttle valve 12 and then enters the rich light-phase solution entering the evaporator 9 through the first recuperator 7 for heating. After that, it is mixed with the rich heavy-phase solution of the phase separator 5 and directly enters the absorber 2 to absorb the rich light-phase steam from the outlet of the expander 1; the absorption liquid of the absorber 2 is pressurized by the second solution pump 11 and then enters the temperature adjustment component 3 for temperature adjustment and is phase-separated again by the phase separator 5. During the operation of the system, the absorber 2 is cooled by circulating water; the evaporator 9 and the temperature adjustment component 3 are heated by low-temperature waste heat.

[0095] When the system uses a partially miscible mixed working fluid pair with the highest consolute temperature, the temperature of the absorption liquid discharged from the absorber 2 is relatively high. The temperature of the mixed solution is lowered to the temperature range of liquid-liquid phase separation through the temperature adjustment component 3, and then it enters the phase separator 5 for phase separation. The obtained rich light-phase solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the rich light-phase solution partially evaporates, and the obtained high-pressure steam enters the expander 1 for power generation; the high-temperature solution that has not evaporated in the evaporator 9 is pressurized by the first throttle valve 12 and then enters the rich light-phase solution entering the evaporator 9 from the phase separator 5 through the first recuperator 7 for heating. After that, it is mixed with the rich heavy-phase solution of the phase separator 5 and directly enters the absorber 2 to absorb the rich light-phase steam from the outlet of the expander 1; the absorption liquid of the absorber 2 is pressurized by the second solution pump 11 and then enters the temperature adjustment component 3 for temperature adjustment and is phase-separated again by the phase separator 5. During the operation of the system, the absorber 2 and the temperature adjustment component 3 are cooled by circulating water; the evaporator 9 is heated by low-temperature waste heat.

[0096] Of course, the temperature adjustment component 3 here is not necessarily a component that must be used. When controlling the outlet temperature of the absorption liquid of the absorber 2 so that the absorption liquid is within the temperature range of liquid-liquid phase separation, the temperature adjustment component 3 does not need to be used at this time, and it directly enters the phase separator 5 for phase separation.

[0097] This embodiment is applicable to the occasions where the heat source temperature is relatively high and the heavy-phase concentration of the solution that has not evaporated in the evaporator is higher than the heavy-phase concentration of the phase separator, and there is no need to add a phase separator for re-concentration.

[0098] Embodiment 3

[0099] The difference from Embodiment 2 is that this embodiment is provided with a second recuperator 13 for heat recovery and utilization of the absorption liquid of the absorber, reducing the heat source usage of the temperature adjustment component 3

[0100] Such as Figure 4, a low-temperature waste heat power generation system based on liquid-liquid phase separation, comprising an expander 1, an absorber 2, a temperature regulating component 3, a second throttle valve 4, a phase separator 5, a pressure reducing component 6, a first recuperator 7, an evaporator 9, a generator 10, a second solution pump 11, a first throttle valve 12, and a second recuperator 13.

[0101] The absorber 2 is provided with a steam inlet, a solution inlet, an absorption liquid outlet, a cooling medium inlet, and a cooling medium outlet; the temperature regulating component 3 is provided with a solution inlet and a solution outlet; the phase separator 5 is provided with a solution inlet, an upper layer solution (light phase solution or low boiling point solution) outlet, and a lower layer solution (heavy phase solution or high boiling point solution) outlet; the first recuperator 7 is provided with a first solution inlet, a first solution outlet, a second solution inlet, and a second solution outlet; the second recuperator 13 is provided with a first solution inlet, a first solution outlet, a second solution inlet, and a second solution outlet; the evaporator 9 is provided with a solution inlet, a solution outlet, a steam outlet, a heating medium inlet, and a heating medium outlet.

[0102] The steam outlet of the expander 1 is connected to the steam inlet of the absorber 2, the solution inlet of the absorber 2 is connected to the first solution outlet of the second recuperator 13, the heavy phase solution outlet of the phase separator 5 is connected to the first solution inlet of the second recuperator 13, and the second throttle valve 4 is installed on the connecting pipeline. The absorption liquid outlet of the absorber 2 is connected to the inlet of the second solution pump 11, the outlet of the second solution pump 11 is connected to the second solution inlet of the second recuperator 13, and the second solution outlet of the second recuperator 13 is connected to the solution inlet of the temperature regulating component 3; the solution outlet of the temperature regulating component 3 is connected to the solution inlet of the phase separator 5; the light phase solution outlet of the phase separator 5 is connected to the first solution inlet of the first recuperator 7, and the pressure reducing component 6 is installed on the connecting pipeline. Here, the pressure reducing component 6 is a throttle valve; the first solution outlet of the first recuperator 7 is connected to the solution inlet of the evaporator 9; the steam outlet of the evaporator 9 is connected to the steam inlet of the expander 1; the expander 1 is connected to the generator 10; the solution outlet of the evaporator 9 is connected to the second solution inlet of the first recuperator 7, and the first throttle valve 12 is installed on the connecting pipeline; the second solution outlet of the first recuperator 7 is connected to the first solution inlet of the second recuperator 13.

[0103] The cooling medium inlet and the cooling medium outlet of the absorber 2 are respectively connected to cooling water; the heating medium inlet and the heating medium outlet of the evaporator 9 are respectively connected to a low-temperature waste heat supply pipeline.

[0104] The working method of this embodiment is as follows:

[0105] When the system uses a partially miscible mixed working fluid pair with the lowest consolute point temperature, the mixed solution is adjusted to the temperature range of liquid-liquid phase separation through the temperature adjustment component 3, and then enters the phase separator 5 for phase separation. The obtained rich light-phase solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the rich light-phase solution is partially evaporated, and the obtained high-pressure steam enters the expander 1 to generate electricity; the high-temperature solution that is not evaporated in the evaporator 9 is pressurized by the first throttle valve 12 and then enters the rich light-phase solution entering the evaporator 9 through the first recuperator 7 for heating. After that, it is mixed with the rich heavy-phase solution of the phase separator 5 and then enters the second recuperator 13 to preheat the mixed solution entering the temperature adjustment component 3. The cooled rich heavy-phase solution enters the absorber 2 to absorb the rich light-phase steam from the outlet of the expander 1; the absorption liquid of the absorber 2 is pressurized by the second solution pump 11, preheated by the second recuperator 13, and then enters the temperature adjustment component 3 for temperature adjustment and is phase-separated again by the phase separator 5. When the system operates, the absorber 2 is cooled by circulating water; the evaporator 9 and the temperature adjustment component 3 are heated by low-temperature waste heat.

[0106] The working method of this embodiment is basically the same as that of Embodiment 2. The difference is that this embodiment is provided with a second recuperator 13 for heat recovery and utilization, thereby reducing the heat source usage of the temperature adjustment component 3 and improving the energy efficiency of the system.

[0107] Embodiment 4

[0108] The difference from Embodiment 1 is that this embodiment is provided with a third recuperator 14 for recovering the high-temperature latent heat of the steam at the outlet of the expander 1 and improving the energy utilization efficiency of the system.

[0109] Such as Figure 5 , a low-temperature waste heat power generation system based on liquid-liquid phase separation, including an expander 1, an absorber 2, a temperature adjustment component 3, a second throttle valve 4, a phase separator 5, a pressure reduction component 6, a first recuperator 7, a first solution pump 8, an evaporator 9, a generator 10, a second solution pump 11, and a third recuperator 14.

[0110] The absorber 2 is provided with a steam inlet, a solution inlet, an absorption liquid outlet, a cooling medium inlet, and a cooling medium outlet; the temperature adjustment component 3 is provided with a solution inlet and a solution outlet; the phase separator 5 is provided with a solution inlet, an upper-layer solution (light-phase solution or low-boiling-point solution) outlet, and a lower-layer solution (heavy-phase solution or high-boiling-point solution) outlet; the first recuperator 7 is provided with a first solution inlet, a first solution outlet, a second solution inlet, and a second solution outlet; the evaporator 9 is provided with a solution inlet, a solution outlet, a steam outlet, a heating medium inlet, and a heating medium outlet. The third recuperator 14 is provided with a steam inlet, a gas-liquid mixture outlet, a solution inlet, and a solution outlet;

[0111] The steam outlet of the expander 1 is connected to the steam inlet of the third regenerator 14. The gas-liquid mixture outlet of the third regenerator 14 is connected to the gas-phase inlet of the absorber 2. The solution inlet of the absorber 2 is connected to the heavy-phase solution outlet of the phase separator 5, and the second throttle valve 4 is installed on the connecting pipeline. The absorption liquid outlet of the absorber 2 is connected to the inlet of the second solution pump 11. The outlet of the second solution pump 11 is connected to the solution inlet of the third regenerator 14. The solution outlet of the third regenerator 14 is connected to the solution inlet of the temperature regulating component 3. The solution outlet of the temperature regulating component 3 is connected to the solution inlet of the phase separator 5. The light-phase solution outlet of the phase separator 5 is connected to the first solution inlet of the first regenerator 7, and the pressure reducing component 6 is installed on the connecting pipeline. Here, the pressure reducing component 6 is a throttle valve. The first solution outlet of the first regenerator 7 is connected to the solution inlet of the evaporator 9. The solution outlet of the evaporator 9 is connected to the inlet of the first solution pump 8. The steam outlet of the evaporator 9 is connected to the steam inlet of the expander 1. The expander 1 is connected to the generator 10. The outlet of the first solution pump 8 is connected to the second solution inlet of the first regenerator 7. The second solution outlet of the first regenerator 7 is connected to the solution inlet of the temperature regulating component 3.

[0112] The cooling medium inlet and the cooling medium outlet of the absorber 2 are respectively connected to the cooling water. The heating medium inlet and the heating medium outlet of the evaporator 9 are respectively connected to the low-temperature waste heat supply pipeline.

[0113] The working method of this embodiment is as follows: The system uses a partially miscible mixed working fluid pair with the lowest consolute temperature. The refrigerant steam released by the expander 1 enters the absorber 2 after heat exchange in the third regenerator 14 and is absorbed by the absorbent located in the absorber 2. After the absorption liquid in the absorber 2 is temperature-regulated by the third regenerator 14 and the temperature regulating component 3, the mixed solution is adjusted to the temperature range of liquid-liquid stratification, and then enters the phase separator 5 for phase separation. The obtained light-phase rich solution enters the evaporator 9 after throttling. Under the heating of the low-temperature heat source, the light-phase rich solution is partially evaporated, and the obtained high-pressure steam enters the expander 1 for expansion power generation. The high-temperature solution that is not evaporated in the evaporator 9 is pressurized by the first solution pump 8 and then enters the light-phase rich solution in the evaporator 9 after being heated by the first regenerator 7, and then enters the temperature regulating component 3 for continuous temperature regulation and phase separation. The heavy-phase rich solution of the phase separator 5 enters the absorber 2 after throttling and pressure reduction to absorb the light-phase rich steam from the outlet of the expander 1. When the system is running, the absorber 2 is cooled by circulating water. The evaporator 9 and the temperature regulating component 3 are heated by low-temperature waste heat.

[0114] The first regenerator 7 in this embodiment is not an essential component. The high-temperature solution that is not evaporated in the evaporator 9 enters the phase separator 5 after being temperature-regulated by the temperature regulating component 3 to concentrate the absorption liquid and improve the absorption efficiency.

[0115] The temperature regulating component 3 in this embodiment is not necessarily used. By recycling heat through the third regenerator 14 to heat up the absorbent solution flowing out of the absorber 2, the effect of liquid-liquid phase separation can be achieved without using the temperature regulating component 3 to further increase the temperature.

[0116] The working method of this embodiment is basically the same as that of Embodiment 1. The difference is that this embodiment is provided with a third regenerator 14, and the low-temperature solution at the outlet of the absorber 2 is heated by the steam at the outlet of the expander 1, thereby reducing the heat consumption of the temperature regulating component 3 or even reducing the use of the temperature regulating component 3, and reducing the heat source consumption of the system.

[0117] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A low-temperature waste heat power generation system based on liquid-liquid phase separation, characterized in that: It includes absorber, phase separator, pressure reducing unit, evaporator, expander and generator. The absorber is provided with a cooling medium inlet and a cooling medium outlet for cooling the absorption liquid in the absorber; The absorption liquid outlet of the absorber is connected to the solution inlet of the phase separator, the upper solution outlet of the phase separator is connected to the evaporator through a pressure reducing component, the lower solution outlet of the phase separator is connected to the solution inlet of the absorber, the steam outlet of the evaporator is connected to the steam inlet of the expander, the steam outlet of the expander is connected to the steam inlet of the absorber, and the expander is connected to a generator for driving the generator to generate electricity; the working fluid pair used in the system is a partially miscible working fluid pair, and the heat source inlet of the evaporator is connected to a waste heat supply pipeline.

2. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1, characterized in that: A temperature regulating component is also provided between the absorber and the phase separator for regulating the temperature of the absorption liquid.

3. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1, characterized in that: A first regenerator is arranged between the phase separator and the evaporator, the upper solution outlet of the phase separator is connected to the first solution inlet of the first regenerator, the first solution outlet of the first regenerator is connected to the solution inlet of the evaporator, the solution outlet of the evaporator is connected to the second solution inlet of the first regenerator, and the second solution outlet of the first regenerator is connected to the solution inlet of the absorber.

4. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 3, characterized in that: A first solution pump is provided between the first regenerator and the evaporator, and the solution outlet of the evaporator is connected to the second solution inlet of the first regenerator through the first solution pump.

5. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 2, characterized in that: A first heat regenerator is arranged between the phase separator and the evaporator, the upper solution outlet of the phase separator is connected to the first solution inlet of the first heat regenerator, the first solution outlet of the first heat regenerator is connected to the solution inlet of the evaporator, the solution outlet of the evaporator is connected to the second solution inlet of the first heat regenerator, and the second solution outlet of the first heat regenerator is connected to the solution inlet of the temperature control component.

6. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 5, characterized in that: A first throttle valve is provided between the first regenerator and the evaporator, and the solution outlet of the evaporator is connected to the second solution inlet of the first regenerator through the first throttle valve.

7. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1, characterized in that: A second solution pump is arranged between the absorber and the phase separator, and is used to transport the absorption liquid in the absorber to the phase separator.

8. The low-temperature waste heat power generation system based on liquid-liquid phase separation according to claim 1, characterized in that: A second throttle valve is arranged between the phase separator and the absorber, the lower solution outlet of the phase separator is connected to the solution inlet of the second throttle valve, and the solution outlet of the second throttle valve is connected to the solution inlet of the absorber.

9. A low-temperature waste heat power generation system based on liquid-liquid phase separation according to any one of claims 2, 5 and 6, characterized in that: A second regenerator is arranged between the absorber and the temperature regulating component, the absorption liquid outlet of the absorber is connected to the first solution inlet of the second regenerator, the first solution outlet of the second regenerator is connected to the temperature regulating component, the lower solution outlet of the phase separator is connected to the second solution inlet of the second regenerator, and the second solution outlet of the second regenerator is connected to the solution inlet of the absorber.

10. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1 or 3, characterized in that: A third regenerator is arranged between the absorber and the expander, the steam outlet of the expander is connected to the first solution inlet of the third regenerator, the first solution outlet of the third regenerator is connected to the steam inlet of the absorber, the absorption liquid outlet of the absorber is connected to the second solution inlet of the third regenerator, and the second solution outlet of the third regenerator is connected to the phase separator.

11. A low-temperature waste heat power generation system based on liquid-liquid phase separation according to any one of claims 2, 5 and 6, characterized in that: A third regenerator is arranged between the absorber and the expander, the steam outlet of the expander is connected to the first solution inlet of the third regenerator, the first solution outlet of the third regenerator is connected to the steam inlet of the absorber, the absorption liquid outlet of the absorber is connected to the second solution inlet of the third regenerator, and the second solution outlet of the third regenerator is connected to the temperature control component.

12. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1, characterized in that: The pressure reducing component is selected from a throttle valve.

13. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 1, characterized in that: The working fluid pair is a binary or ternary partially miscible working fluid pair.

14. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 13, characterized in that: The working fluid pair is a working fluid pair with a highest melting point temperature or a working fluid pair with a lowest melting point temperature.

15. A low-temperature waste heat power generation system based on liquid-liquid phase separation as claimed in claim 14, characterized in that: The working fluid pair is selected from any one of water-triethylamine, water-phenol, water-isobutanol, water-aniline, nitrobenzene-n-hexane, Freon-refrigeration oil, water-ionic liquid, n-hexane-diethylene glycol-benzene, ethanol-water-acetonitrile, and ether-water-acetonitrile.

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