Binary non-azeotropic working medium medium and low temperature power generation system

Abstract

The invention discloses a binary non-azeotropic working medium medium-low temperature power generation system which comprises a medium-low temperature heat source, a high-temperature evaporator, a low-temperature evaporator, a high-pressure separator, a medium-pressure separator, a high-pressure working medium pump, a high-temperature preheater and an air supply type expansion machine. A heat source inlet of the high-temperature evaporator communicates with a medium-low-temperature heat source, a heat source outlet of the high-temperature evaporator communicates with a heat source inlet of the low-temperature evaporator, and a working medium outlet and a working medium inlet of the high-temperature evaporator communicate with a working medium inlet of the high-pressure separator and a working medium outlet of the high-temperature preheater correspondingly. A working medium outlet of the low-temperature evaporator communicates with a working medium inlet of the medium-pressure separator; an air outlet of the medium-pressure separator and an air outlet of the high-pressure separator are respectively communicated with an air inlet and an air supply port of the expansion machine; a liquid outlet of the medium-pressure separator is communicated with a working medium inlet of the high-temperature preheater; a heat source outlet of the high-temperature preheater communicates with a working medium inlet of the low-temperature evaporator; and a liquid outlet of the high-pressure separator is communicated with a heat source inlet of the high-temperature preheater. The invention aims to realize efficient gradient utilization of heat energy.

Description

Technical Field

[0001] The present invention relates to the technical field of medium and low temperature energy utilization, and in particular to a medium and low temperature power generation system using a binary non-azeotropic working fluid. Background Art

[0002] Energy is the material basis for human survival and economic development. Solar energy, geothermal energy, biomass energy and industrial waste heat resources are gradually being valued by humans due to their abundant quantity, huge utilization potential and ability to achieve sustainable energy development. However, these energy sources have low energy quality and low energy flow density, resulting in low resource utilization rate and high utilization input cost.

[0003] Among the ways to utilize medium- and low-temperature thermal energy, power generation can improve energy quality, offer flexible utilization methods, and offer high economic benefits. Typical technologies for utilizing medium- and low-temperature thermal energy include the organic Rankine cycle, the Kalina cycle, the steam Rankine cycle, the Stirling cycle, the Ericsson cycle, and thermoelectric conversion. The organic Rankine cycle, which utilizes a non-azeotropic mixture as a refrigerant, is an effective technology for recovering medium- and low-temperature thermal energy. The Rankine cycle utilizes a low-boiling-point organic refrigerant to convert low-quality energy into high-quality electricity, effectively utilizing medium- and low-temperature resources. It also offers advantages such as a simple structure, low technical requirements, and excellent economic efficiency.

[0004] However, in the current low-temperature thermal power generation system that adopts the organic Rankine cycle, due to the mismatch of heat exchange temperature during the construction of the thermal system, some high-quality thermal energy cannot be utilized in a cascade manner, and the pressure energy of the liquid working fluid in gas-liquid separation cannot be reasonably utilized, which limits the improvement of the overall cycle thermal efficiency and power generation efficiency. Summary of the Invention

[0005] The main purpose of the present invention is to provide a medium- and low-temperature power generation system using a binary non-azeotropic working fluid, aiming to achieve efficient cascade utilization of medium- and low-temperature thermal energy, explore the work-doing capacity of the working fluid, and improve the energy utilization efficiency of waste heat resources.

[0006] To achieve the above-mentioned purpose, the present invention proposes a medium- and low-temperature power generation system using a binary non-azeotropic working fluid, comprising a medium- and low-temperature heat source, a high-temperature evaporator, a low-temperature evaporator, a high-pressure separator, a medium-pressure separator, a high-pressure working fluid pump, a high-temperature preheater, and an air-compensating expander;

[0007] The heat source inlet of the high-temperature evaporator is connected to the medium- and low-temperature heat sources, the heat source outlet of the high-temperature evaporator is connected to the heat source inlet of the low-temperature evaporator, and the working fluid outlet of the high-temperature evaporator is connected to the working fluid inlet of the high-pressure separator;

[0008] The working fluid outlet of the low-temperature evaporator is connected to the working fluid inlet of the medium-pressure separator;

[0009] The gas outlet of the medium-pressure separator is connected to the gas supply port of the expander, the liquid outlet of the medium-pressure separator is connected to the working fluid inlet of the high-pressure working fluid pump, and the working fluid outlet of the high-pressure working fluid pump is connected to the working fluid inlet of the high-temperature preheater;

[0010] The heat source outlet of the high temperature preheater is connected to the working fluid inlet of the low temperature evaporator, and the working fluid outlet of the high temperature preheater is connected to the working fluid inlet of the high temperature evaporator;

[0011] The air outlet of the high-pressure separator is connected to the air inlet of the expander, and the liquid outlet of the high-pressure separator is connected to the heat source inlet of the high-temperature preheater.

[0012] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system further includes a condenser, a medium-pressure working fluid pump, and an exhaust heat regenerator;

[0013] The exhaust steam outlet of the expander is connected to the heat source inlet of the exhaust regenerator;

[0014] The heat source outlet of the exhaust heat regenerator is connected to the working medium inlet of the condenser;

[0015] The working fluid outlet of the condenser is connected to the working fluid inlet of the medium-pressure working fluid pump;

[0016] The working fluid outlet of the medium-pressure working fluid pump is connected to the working fluid inlet of the exhaust heat regenerator, and the working fluid outlet of the exhaust heat regenerator is connected to the working fluid inlet of the low-temperature evaporator.

[0017] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system further includes a low-temperature preheater; the heat source inlet of the low-temperature preheater is connected to the heat source outlet of the high-temperature preheater, the heat source outlet of the low-temperature preheater is connected to the working fluid inlet of the condenser, the working fluid inlet of the low-temperature preheater is connected to the working fluid outlet of the exhaust heat regenerator, and the working fluid outlet of the low-temperature preheater is connected to the working fluid inlet of the low-temperature evaporator.

[0018] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system also includes a liquid turbine, the heat source outlet of the low-temperature preheater is connected to the liquid inlet of the liquid turbine, the liquid outlet of the liquid turbine is connected to the working fluid inlet of the condenser, and the liquid turbine is used to drive the high-pressure working fluid pump.

[0019] Optionally, the high-pressure separator is arranged at a high position, and the condenser is arranged at a low position, and the high-temperature preheater, the low-temperature preheater and the high-pressure working fluid pump are sequentially arranged between the high-pressure separator and the condenser.

[0020] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system further includes a low-temperature preheater, a condenser, and a medium-pressure working fluid pump;

[0021] The heat source inlet of the low-temperature preheater is connected to the heat source outlet of the high-temperature preheater, the heat source outlet of the low-temperature preheater is connected to the working fluid inlet of the condenser, the working fluid inlet of the low-temperature preheater is connected to the working fluid outlet of the condenser, and the working fluid outlet of the low-temperature preheater is connected to the working fluid inlet of the low-temperature evaporator.

[0022] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system also includes a liquid turbine, the heat source outlet of the low-temperature preheater is connected to the liquid inlet of the liquid turbine, the liquid outlet of the turbine is connected to the working fluid inlet of the condenser, and the turbine is used to drive the high-pressure working fluid pump.

[0023] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system further includes an air supply valve, which is provided between the air outlet of the medium-pressure separator and the air supply port;

[0024] The expander is provided with an annular mixed air supply stage, which is arranged in the expander near the air supply port of the expander and is also arranged between the air inlet and the air outlet.

[0025] Optionally, the binary non-azeotropic working fluid medium- and low-temperature power generation system further includes a power generation device, the power generation device includes at least one generator, and the output end of the expander is drivingly connected to the generator.

[0026] Optionally, the medium and low temperature heat source is one or more of a solar heat source, a geothermal heat source, a biomass energy source or an industrial waste heat source.

[0027] The basic principle of the binary non-azeotropic working fluid medium- and low-temperature power generation system proposed by the present invention is: the binary non-azeotropic mixed working fluid (formed by mixing two pure working fluids with different boiling points in a certain proportion) absorbs low-grade heat energy from the heat source through the low-temperature section evaporator to evaporate, generating a medium-temperature and medium-pressure gas-liquid two-phase mixed working fluid, which then enters the medium-pressure separator to separate medium-concentration saturated liquid working fluid and high-concentration saturated gaseous working fluid. The high-concentration saturated gaseous working fluid enters the expander with the above-mentioned heating to an overheated state and then expands to generate electricity. The medium-concentration saturated liquid working fluid is pressurized by the high-pressure working fluid pump and then enters the high-temperature preheater and the high-temperature section evaporator to absorb high-grade heat energy from the heat source to generate high-temperature and high-pressure saturated working fluid. After gas-liquid separation in the high-pressure separator, low-concentration saturated liquid working fluid and high-concentration saturated gaseous working fluid are separated. The high-concentration saturated gaseous working fluid enters the expander to partially expand and generate electricity, and the low-concentration saturated liquid working fluid is heat exchanged and supercooled in the high-temperature preheater and then enters the low-temperature section evaporator, thereby completing a two-stage separation and air-supplementing double-effect power generation cycle. The present invention increases the pressure of the medium-concentration saturated liquid working medium separated by the medium-pressure separator by adding a high-pressure working medium pump, and then feeds it into the high-temperature preheater to recover the heat of the liquid working medium separated by the high-pressure separator, so that it can re-enter the low-temperature section evaporator for circulation, thereby exploring the working capacity of the working medium, improving the energy utilization rate of the system, and realizing efficient cascade utilization of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0029] Figure 1 This is a schematic structural diagram of the low-binary non-azeotropic working fluid medium- and low-temperature power generation system provided by the present invention.

[0030] Figure 2 This is a temperature-entropy (TS) diagram of the low-temperature power generation system using a binary non-azeotropic working fluid according to the present invention;

[0031] Figure 3 This is a boiling point-composition diagram (Tx diagram) of the binary non-azeotropic working fluid in the low-temperature power generation system of the binary non-azeotropic working fluid of the present invention.

[0032] Description of Figure Numbers:

[0033] Label name Label name 1000 Medium and low temperature power generation system with binary non-azeotropic working fluid 107 Air-injection expander 100 Medium and low temperature heat source 108 Annular mixing air supply stage 101 High temperature evaporator 109 Condenser 102 Low temperature evaporator 110 Medium pressure working fluid pump 103 High-pressure separator 111 Exhaust heat regenerator 104 Medium pressure separator 112 Low temperature preheater 105 High-pressure working fluid pump 113 hydraulic turbine 106 High temperature preheater 114 dynamo

[0034] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0037] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] See also Figure 1 The present invention provides a medium- and low-temperature power generation system 1000 using a binary non-azeotropic working fluid, comprising a medium- and low-temperature heat source 100, a high-temperature evaporator 101, a low-temperature evaporator 102, a high-pressure separator 103, a medium-pressure separator 104, a high-pressure working fluid pump 105, a high-temperature preheater 106, and an air-supplementing expander 107; the heat source inlet of the high-temperature evaporator 101 is connected to the medium- and low-temperature heat source 100, the heat source outlet of the high-temperature evaporator 101 is connected to the heat source inlet of the low-temperature evaporator 102, the working fluid outlet of the high-temperature evaporator 101 is connected to the working fluid inlet of the high-pressure separator 103; the working fluid outlet of the low-temperature evaporator 102 is connected to the working fluid inlet of the medium-pressure separator 103; The working fluid inlet of the expander 104; the air outlet of the medium-pressure separator 104 is connected to the second air supply port of the expander 107, the liquid outlet of the medium-pressure separator 104 is connected to the working fluid inlet of the high-pressure working fluid pump 105, and the working fluid outlet of the high-pressure working fluid pump 105 is connected to the working fluid inlet of the high-temperature preheater 106; the heat source outlet of the high-temperature preheater 106 is connected to the working fluid inlet of the low-temperature evaporator 102, and the working fluid outlet of the high-temperature preheater 106 is connected to the working fluid inlet of the high-temperature evaporator 101; the air outlet of the high-pressure separator 103 is connected to the air supply port of the expander 107, and the liquid outlet of the high-pressure separator 103 is connected to the heat source inlet of the high-temperature preheater 106.

[0039] The basic principle of the binary non-azeotropic medium-low temperature power generation system 1000 proposed by the present invention is: the binary non-azeotropic mixed working fluid (composed of two pure working fluids with different boiling points mixed in a certain proportion) absorbs the low-grade heat energy of the heat source through the low-temperature section evaporator to evaporate, generating a medium-temperature medium-pressure gas-liquid two-phase mixed working fluid, which then enters the medium-pressure separator 104 to separate the medium-concentration saturated liquid working fluid and the high-concentration saturated gaseous working fluid. The high-concentration saturated gaseous working fluid enters the annular mixing air-supplementing stage 108 in the air-supplementing expander 107 and is mixed and heated to an overpressure. After the hot state, the medium-concentration saturated liquid phase working fluid is pressurized by the high-pressure working fluid pump 105 and enters the high-temperature preheater 106. The high-temperature section evaporator absorbs the high-quality heat energy of the heat source to produce high-temperature and high-pressure saturated working fluid. After gas-liquid separation by the high-pressure separator 103, low-concentration saturated liquid phase working fluid and high-concentration saturated gaseous working fluid are separated. The high-concentration saturated gaseous working fluid enters the expander 107 to expand and generate electricity. The low-concentration saturated liquid phase working fluid is heat-exchanged and supercooled by the high-temperature preheater 106 and then enters the low-temperature section evaporator, thus completing a power generation cycle. The present invention increases the pressure of the medium-concentration saturated liquid phase working fluid separated by the medium-pressure separator 104 by adding a high-pressure working fluid pump 105 and enters the high-temperature preheater 106 to recover the heat of the liquid working fluid separated by the high-pressure separator 103, so that it can re-enter the low-temperature section evaporator for circulation, thereby exploring the work capacity of the working fluid, improving the energy utilization rate of the system, and realizing efficient cascade utilization of energy.

[0040] In one embodiment of the present application, the binary non-azeotropic working fluid medium and low temperature power generation system 1000 also includes a condenser 109, a medium-pressure working fluid pump 110 and an exhaust heat regenerator 111; the exhaust steam outlet of the expander 107 is connected to the heat source inlet of the exhaust heat regenerator 111; the heat source outlet of the exhaust heat regenerator 111 is connected to the working fluid inlet of the condenser 109; the working fluid outlet of the condenser 109 is connected to the working fluid inlet of the medium-pressure working fluid pump 110; the working fluid outlet of the medium-pressure working fluid pump 110 is connected to the working fluid inlet of the exhaust heat regenerator 111, and the working fluid outlet of the exhaust heat regenerator 111 is connected to the working fluid inlet of the low-temperature evaporator 102. Specifically, the gaseous working medium separated by the high-pressure separator 103 and the low-pressure separator enters the expander 107 for expansion, generating power. The saturated gaseous working medium after expansion is converted into exhaust gas. The superheated exhaust gas is cooled to a saturated state 3 by the exhaust regenerator 111. The exhaust gas then enters the condenser 109 and is condensed into a saturated or subcooled liquid phase 4. The exhaust gas is then pressurized by the medium-pressure working medium pump 110 and preheated by the exhaust regenerator 111 before entering the low-temperature evaporator. This allows the exhaust gas to be reused in the system, improving its thermal efficiency and energy utilization.

[0041] In one embodiment of the present application, the binary non-azeotropic medium- and low-temperature power generation system 1000 further includes a low-temperature preheater 112; the heat source inlet of the low-temperature preheater 112 is connected to the heat source outlet of the high-temperature preheater 106, the heat source outlet of the low-temperature preheater 112 is connected to the working fluid inlet of the condenser 109, the working fluid inlet of the low-temperature preheater 112 is connected to the working fluid outlet of the exhaust gas regenerator 111, and the working fluid outlet of the low-temperature preheater 112 is connected to the working fluid inlet of the low-temperature evaporator 102. Specifically, the low-concentration saturated liquid phase working fluid 14 is discharged into the condenser 109 after heat exchange with the high-temperature preheater 106 and the low-temperature preheater 112, and the liquid phase working fluid after being supercooled is discharged into the condenser 109. After mixing with the exhaust gas 3 from the expander 107, it is condensed into a saturated or supercooled liquid phase 4, and then pressurized by the medium-pressure working fluid pump 110, enters the exhaust gas regenerator 111 and the low-temperature preheater 112 for preheating, and then enters the low-temperature section evaporator. In this way, the low-concentration saturated liquid phase working medium after gas-liquid separation in the high-pressure separator 103 is cooled by the high-temperature preheater 106 and the low-temperature preheater 112, and at the same time, the saturated or subcooled liquid phase 4 condensed by the condenser 109 is heated in the exhaust heat regenerator 111 and the low-temperature preheater 112. The circulation of the working medium further completes the two-stage or multi-stage heat exchange effect, further realizes the efficient cascade utilization of thermal energy, and improves the energy utilization rate of waste heat resources.

[0042] In one embodiment of the present application, a binary non-azeotropic medium- and low-temperature power generation system 1000 further includes a turbine 113. The heat source outlet of the low-temperature preheater 112 is connected to the liquid inlet of the turbine 113, and the liquid outlet of the turbine 113 is connected to the working medium inlet of the condenser 109. The turbine 113 is used to drive the high-pressure working medium pump 105. After undergoing heat exchange and subcooling in the high-temperature preheater 106 and the low-temperature preheater 112, the low-concentration saturated liquid phase working medium 14 is discharged into the turbine 113, which drives the high-pressure working medium pump 105. The liquid phase working medium 17 at the outlet of the turbine 113 is discharged into the condenser 109, where it mixes with the exhaust gas 3 from the expander 107 and is condensed into a saturated or subcooled liquid phase 4. This further enhances the working medium's workability and reduces the initial investment in the equipment.

[0043] In one embodiment of the present application, the high-pressure separator 103 is arranged at a high position, the condenser 109 is arranged at a low position, and the high-temperature preheater 106, the low-temperature preheater 112, and the high-pressure working fluid pump 105 are sequentially arranged between the high-pressure separator 103 and the condenser 109. The sum of the gravitational potential energy of the liquid working fluid separated by the high-pressure separator 103 and the pressure potential energy between the high-pressure separator 103 and the condenser 109 is used as the driving kinetic energy of the high-pressure working fluid pump 105. The head of the high-pressure working fluid pump 105 is self-coupled with the liquid turbine 113 to achieve self-matching of pressure.

[0044] Of course, in other embodiments, according to different actual heat exchange conditions, it is also possible not to set up the exhaust heat regenerator 111 for heat recovery, but to directly use the low-temperature preheater 112 to achieve the effect of cooling and heat exchange. Specifically, the binary non-azeotropic working fluid medium and low-temperature power generation system 1000 also includes a turbine 113 and a low-temperature preheater 112; the heat source inlet of the low-temperature preheater 112 is connected to the heat source outlet of the high-temperature preheater 106, the heat source outlet of the low-temperature preheater 112 is connected to the liquid inlet of the turbine 113, the working fluid inlet of the low-temperature preheater 112 is connected to the working fluid outlet of the condenser 109, and the working fluid outlet of the low-temperature preheater 112 is connected to the working fluid inlet of the low-temperature evaporator 102; the liquid outlet of the turbine 113 is connected to the working fluid inlet of the condenser 109, and the turbine 113 is used to drive the high-pressure working fluid pump 105. Furthermore, the binary non-azeotropic working fluid medium and low temperature power generation system 1000 also includes a turbine 113, the heat source outlet of the low temperature preheater 112 is connected to the liquid inlet of the turbine 113, and the liquid outlet of the turbine 113 is connected to the working fluid inlet of the condenser 109, and the turbine 113 is used to drive the high-pressure working fluid pump 105.

[0045] In one embodiment of the present application, the binary non-azeotropic working fluid medium and low temperature power generation system 1000 also includes an air supply valve, which is arranged between the air outlet and the air supply port of the medium pressure separator 104; the expander 107 is provided with an annular mixed air supply stage 108, and the annular mixed air supply stage 108 is arranged in the expander 107 near the air supply port of the expander 107, and the annular mixed air supply stage 108 is also arranged between the air inlet and the air outlet. In order to optimize the working efficiency of the working medium in the air-supplement expander 107, a suitable expansion stage is selected and set on the expander 107 according to the characteristic parameters of the saturated gaseous working medium separated by the medium-pressure separator 104. In the annular mixed air-supplement stage 108, the medium-pressure saturated steam separated by the medium-pressure separator 104 is replenished to the annular mixed air-supplement stage 108 of the expander 107 through the air-supplement valve, and is mixed with the superheated working medium by the medium-pressure saturated steam to achieve uniform working medium composition. At the same time, the medium-pressure saturated steam can be used to cool the superheated working medium, reduce the superheat of the exhaust gas of the expander 107, and increase the working capacity of the mixed working medium in the expander 107.

[0046] In one embodiment of the present application, the medium- and low-temperature heat source 100 is one or more of solar heat, geothermal heat, biomass energy, or industrial waste heat. These renewable energy sources are widely used in heating, hot water, power generation, and other fields, helping to reduce dependence on traditional fossil energy, lowering energy consumption while also reducing environmental pollution.

[0047] In one embodiment of the present application, the binary non-azeotropic medium-low temperature power generation system 1000 further includes a power generation device, which includes at least one generator 114 , and the output end of the expander 107 is driven and connected to the generator 114 .

[0048] In one embodiment of this application, please refer to Figure 3 , Figure 3 The boiling point-composition diagram (Tx diagram) of the binary non-azeotropic working fluid medium-low temperature power generation system 1000 of the present invention is shown. For the binary mixed working fluid system, the working fluid 8 at a temperature of T is separated by distillation into a gas phase 9 and a liquid phase 10. The liquid phase 10 is heated and pressurized and then migrates to the working fluid 13 at a temperature of T. The working fluid 13 is then separated by distillation into a liquid phase 14 and a gas phase 1. Figure 3 It can be clearly seen that after a certain composition, as the components increase, the dew point temperature line decreases linearly, that is, Δx / ΔT→0. Therefore, when the two-component mixed working fluid is subjected to two-stage distillation, the composition of the saturated gas phase working fluid separated by the high-pressure separator 103 and the medium-pressure separator 104 is basically the same, that is, x1≈x9. Therefore, the working capacity of the saturated steam generated by the high-pressure separator 103 and the medium-pressure separator 104 recovered by an air-supplementing expander 107 can be used to reduce the initial investment in the equipment.

[0049] In summary, the present invention comprises a high-efficiency, cascaded waste heat power generation device, comprising two-stage working fluid pumps (a high-pressure working fluid pump 105 and a medium-pressure working fluid pump 110 driven by a turbine 113), a two-stage gas-liquid separator (a high-pressure separator 103 and a medium-pressure separator 104), an air-compensating expander 107, and corresponding heat exchange devices (an exhaust regenerator 111, a condenser 109, a high-temperature preheater 106, a low-temperature preheater 112, a low-temperature evaporator, and a high-temperature evaporator). The low-temperature power generation device proposed in this invention couples four heat engine forward cycles and one reverse cycle. In addition, a description is given of the binary non-azeotropic working fluid. The circulating working fluid at the outlet of the low-temperature section evaporator and the inlet of the medium-pressure separator 104 is defined as the working working fluid. The corresponding medium-pressure separator 104 separates the high-high concentration mixed working fluid and the medium-concentration mixed working fluid, and the high-pressure separator 103 separates the high-concentration mixed working fluid and the low-concentration mixed working fluid. Since the dew point line of the circulating working fluid used in the present invention has a parabolic drop characteristic after a certain composition (see Figure 3 ), so the composition of the high-high-concentration mixed working fluid and the high-concentration mixed working fluid is not much different, and the following description is based on the high-concentration mixed working fluid. The thermodynamic cycle process of the binary non-azeotropic working fluid medium-low temperature power generation system 1000 proposed by the present invention is mainly composed of four heat engine positive cycles and a refrigeration reverse cycle coupled, namely:

[0050] 1) The main cycle consists of a condenser 109, a medium-pressure working fluid pump 110, an exhaust regenerator 111, a low-temperature preheater 112, a low-temperature section evaporator, and a medium-pressure separator 104. The working fluid flowing in the main cycle is the working fluid, and the working fluid flow rate is m A +m B +m CThe working medium state point between the condenser 109 and the medium-pressure separator 104 migrates as follows: in the condenser 109, the exhaust gas of the air-supplementing expander 107 is fully mixed with the outlet liquid phase working medium of the turbine 113 to reduce the temperature, and the saturated working medium 3' is condensed by the condenser 109, and its state changes to the low-pressure liquid phase working medium 4. The mixed working medium 5 after being pressurized by the medium-pressure working medium pump 110 absorbs the superheated heat of the exhaust steam mixed working medium 2 in the exhaust regenerator 111, and the temperature is initially increased, and the state changes to the medium-pressure liquid phase 7. Then, the mixed working medium enters the low-temperature preheater 112 for heat exchange, and the temperature is further increased. Then, the working medium enters the low-temperature section evaporator to absorb waste heat, and its working medium state changes to the medium-temperature medium-pressure saturated mixed working medium 8. According to the above state points, the temperature-entropy diagram (TS diagram) of the cycle is drawn, as shown Figure 2 As shown in the figure, the state point migration of the mixed working medium constructed by the main cycle is: 3'→4→5→6→8. If a dotted line is added to connect the points 8→3', the state point migration of the mixed working medium completes a working medium flow rate of m A +m B +m C The heat engine is in positive cycle.

[0051] 2) The high-pressure positive cycle consists of a medium-pressure separator 104, a high-pressure working fluid pump 105, a high-temperature preheater 106, a high-temperature section evaporator, and a high-pressure separator 103. The working fluid in the high-pressure positive cycle is a medium-concentration mixed working fluid with a working fluid flow rate of m A +m B , its state changes as follows: the mixed working medium 8 heated by the low-temperature section evaporator releases heat in the medium-pressure separator 104 to separate the saturated liquid mixed working medium 10, the working medium 10 is pressurized by the high-pressure working medium pump 105 and then input into the high-temperature preheater 106 for preheating, and then sent to the high-temperature section evaporator to further heat it to a high-temperature and high-pressure saturated mixed working medium 13. Based on the above state points, the temperature-entropy diagram (TS diagram) of the cycle is drawn, as shown Figure 2 As shown in the figure, the state point migration of the mixed working medium constructed by the high-pressure positive cycle is: 8→10→11→13. If a dotted line is added to connect the points 13→8, the state point migration of the mixed working medium completes a working medium flow rate of m A +m B The heat engine is in positive cycle.

[0052] 3) The high-pressure power generation cycle consists of a high-pressure separator 103, an air-supplementing expansion generator 114, an exhaust heat regenerator 111, and a condenser 109. The working fluid in the high-pressure power generation cycle is a high-concentration mixed working fluid with a working fluid flow rate of m A, its state changes as follows: the mixed working medium 13 heated by the high-temperature section evaporator absorbs heat in the high-pressure separator 103 to separate the saturated gaseous mixed working medium 1, which expands and generates electricity in the air-supplementing expansion generator 114 to the annular mixed air-supplementing stage 108. The working medium state is 1', and the mixed working medium entering the annular mixed air-supplementing stage 108 is mixed with the saturated gaseous working medium separated in the medium-pressure separator 104 and cooled to 9'. After cooling, it continues to expand and do work in the blades after the air-supplementing stage of the expander 107, and then discharges from the expander 107. The exhaust gas is a low-pressure working medium 2 with a certain degree of superheat, and then is cooled by the exhaust regenerator 111 3 and discharged into the condenser 109 to mix with the liquid working medium at the outlet of the turbine 113. The working medium state changes to a saturated working working medium 3'. According to the above state points, the temperature-entropy diagram (TS diagram) of the cycle is drawn, as shown Figure 2 As shown in the figure, the state point migration of the mixed working fluid constructed by the high-voltage power generation cycle is: 13→1→1'→9'→2→3→3'. If two dotted lines are added to connect the points 3'→8 and 8→13, the state point migration of the mixed working fluid completes a working fluid flow rate of m A The heat engine is in positive cycle.

[0053] 4) The medium-pressure power generation cycle consists of a medium-pressure separator 104, an air-supplementing expansion generator 114, an exhaust heat regenerator 111, and a condenser 109. The working fluid in the medium-pressure power generation cycle is a high-concentration mixed working fluid with a working fluid flow rate of m C , its state changes as follows: the mixed working medium 8 heated by the low-temperature section evaporator absorbs heat in the medium-pressure separator 104 to separate the saturated gaseous mixed working medium 9, which enters the annular mixed air supply stage 108, and is mixed with the saturated gaseous working medium 1' that has been partially expanded and done work separated in the high-pressure separator 103 and heated to 9'. The heated working medium works to generate electricity in the expander 107, and then is discharged from the expander 107. The exhaust gas is a low-pressure working medium 2 with a certain degree of superheat, and then is cooled by the exhaust regenerator 111 and discharged into the condenser 109 3 to mix with the liquid working medium at the outlet of the turbine 113. The working medium state changes to a saturated working working medium 3'. Based on the above state points, the temperature-entropy diagram (TS diagram) of the cycle is drawn, as shown Figure 2 As shown in the figure, the state point migration of the mixed working fluid constructed by the medium voltage power generation cycle is: 8→9→9'→2→3→3'. If a dotted line is added to connect the points 3'→8, the state point migration of the mixed working fluid completes a working fluid flow rate of m C The heat engine is in positive cycle.

[0054] 5) The reverse cycle consists of a high-pressure separator 103, a high-temperature preheater 106, a low-temperature preheater 112, a turbine 113, and a condenser 109. The working medium in the reverse cycle is a low-concentration liquid phase working medium, and the working medium flow rate is m B, its state changes as follows: the mixed working medium 13 heated by the high-temperature evaporator releases heat in the high-pressure separator 103 to separate into a saturated liquid-phase mixed working medium 14, which is supercooled by heat exchange in the high-temperature preheater 106 and the low-temperature preheater 112 and then discharged into the liquid turbine 113. The liquid-phase working medium drives the liquid turbine 113 to drive the high-pressure working medium pump 105 to operate. The liquid-phase working medium at the outlet of the liquid turbine 113 is discharged into the condenser 109 and mixed with the exhaust gas of the air-compensating expander 107. The working medium state changes to a saturated working working medium 3'. Based on the above state points, the temperature-entropy diagram (TS diagram) of the cycle is drawn, as shown Figure 2 As shown in the figure, the state point migration of the mixed working medium constructed by reverse circulation is: 13→14→16→17→3'. If two dotted lines are added to connect 3'→8 and 8→13, the state point migration of the mixed working medium completes a working medium flow rate of m B refrigeration reverse cycle.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's description and drawings, or direct / indirect applications in other related technical fields, within the scope of the present invention are included in the patent protection scope of the present invention.

Claims

1. A binary non-azeotropic medium-low temperature power generation system, characterized in that: The binary non-azeotropic medium- and low-temperature power generation system includes a medium- and low-temperature heat source, a high-temperature evaporator, a low-temperature evaporator, a high-pressure separator, a medium-pressure separator, a high-pressure working fluid pump, a high-temperature preheater, and an air-compensating expander; The heat source inlet of the high-temperature evaporator is connected to the medium- and low-temperature heat sources, the heat source outlet of the high-temperature evaporator is connected to the heat source inlet of the low-temperature evaporator, and the working fluid outlet of the high-temperature evaporator is connected to the working fluid inlet of the high-pressure separator; The working fluid outlet of the low-temperature evaporator is connected to the working fluid inlet of the medium-pressure separator; The gas outlet of the medium-pressure separator is connected to the gas supply port of the expander, the liquid outlet of the medium-pressure separator is connected to the working fluid inlet of the high-pressure working fluid pump, and the working fluid outlet of the high-pressure working fluid pump is connected to the working fluid inlet of the high-temperature preheater; The heat source outlet of the high temperature preheater is connected to the working fluid inlet of the low temperature evaporator, and the working fluid outlet of the high temperature preheater is connected to the working fluid inlet of the high temperature evaporator; The air outlet of the high-pressure separator is connected to the air inlet of the expander, and the liquid outlet of the high-pressure separator is connected to the heat source inlet of the high-temperature preheater.

2. The binary non-azeotropic medium and low temperature power generation system according to claim 1, characterized in that: The binary non-azeotropic working fluid medium and low temperature power generation system further includes a condenser, a medium pressure working fluid pump and an exhaust heat regenerator; The exhaust steam outlet of the air-supplementing expander is connected to the heat source inlet of the exhaust regenerator; The heat source outlet of the exhaust heat regenerator is connected to the working medium inlet of the condenser; The working fluid outlet of the condenser is connected to the working fluid inlet of the medium-pressure working fluid pump; The working fluid outlet of the medium-pressure working fluid pump is connected to the working fluid inlet of the exhaust heat regenerator, and the working fluid outlet of the exhaust heat regenerator is connected to the working fluid inlet of the low-temperature evaporator.

3. The binary non-azeotropic medium and low temperature power generation system according to claim 2, characterized in that: The binary non-azeotropic working fluid medium- and low-temperature power generation system also includes a low-temperature preheater; the heat source inlet of the low-temperature preheater is connected to the heat source outlet of the high-temperature preheater, the heat source outlet of the low-temperature preheater is connected to the working fluid inlet of the condenser, the working fluid inlet of the low-temperature preheater is connected to the working fluid outlet of the exhaust reheater, and the working fluid outlet of the low-temperature preheater is connected to the working fluid inlet of the low-temperature evaporator.

4. The binary non-azeotropic medium and low temperature power generation system according to claim 3, characterized in that: The binary non-azeotropic working fluid medium- and low-temperature power generation system also includes a liquid turbine, the heat source outlet of the low-temperature preheater is connected to the liquid inlet of the liquid turbine, the liquid outlet of the liquid turbine is connected to the working fluid inlet of the condenser, and the liquid turbine is used to drive the high-pressure working fluid pump.

5. The binary non-azeotropic medium and low temperature power generation system according to claim 1, characterized in that: The binary non-azeotropic working fluid medium- and low-temperature power generation system further includes a low-temperature preheater, a condenser, and a medium-pressure working fluid pump; The heat source inlet of the low-temperature preheater is connected to the heat source outlet of the high-temperature preheater, the heat source outlet of the low-temperature preheater is connected to the working fluid inlet of the condenser, the working fluid inlet of the low-temperature preheater is connected to the working fluid outlet of the condenser, and the working fluid outlet of the low-temperature preheater is connected to the working fluid inlet of the low-temperature evaporator.

6. The binary non-azeotropic medium and low temperature power generation system according to claim 5, characterized in that: The binary non-azeotropic working fluid medium- and low-temperature power generation system also includes a liquid turbine, the heat source outlet of the low-temperature preheater is connected to the liquid inlet of the turbine, the liquid outlet of the turbine is connected to the working fluid inlet of the condenser, and the liquid turbine is used to drive the high-pressure working fluid pump.

7. The binary non-azeotropic medium and low temperature power generation system according to any one of claims 3 to 6, characterized in that: The high-pressure separator is arranged at a high position, and the condenser is arranged at a low position. The high-temperature preheater, the low-temperature preheater and the high-pressure working medium pump are sequentially arranged between the high-pressure separator and the condenser.

8. The binary non-azeotropic medium and low temperature power generation system according to any one of claims 1 to 6, characterized in that: The binary non-azeotropic medium- and low-temperature power generation system further includes an air supply valve, which is arranged between the air outlet of the medium-pressure separator and the air supply port; The expander is provided with an annular mixed air supply stage, which is arranged in the expander near the air supply port of the expander and is also arranged between the air inlet and the air outlet.

9. The binary non-azeotropic medium and low temperature power generation system according to any one of claims 1 to 6, characterized in that: The binary non-azeotropic medium- and low-temperature power generation system further includes a power generation device, which includes at least one generator. The output end of the expander is drivingly connected to the generator.

10. The binary non-azeotropic medium and low temperature power generation system according to any one of claims 1 to 6, characterized in that: The medium and low temperature heat source is one or more of solar heat source, geothermal heat source, biomass energy or industrial waste heat source.

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