Supercritical carbon dioxide cycle power generation system and working method and solar thermal power generation system

Abstract

The application discloses a supercritical carbon dioxide cycle power generation system and a working method and a solar thermal power generation system, and relates to the technical field of power generation. The supercritical carbon dioxide cycle power generation system comprises a compressor, a cooler, a first regenerator, a heat exchanger, a first turbine, a second regenerator, a second turbine and a third turbine; the compressor is connected with the low-temperature side inlet of the first regenerator; the low-temperature side outlet of the first regenerator is connected with the low-temperature side inlet of the heat exchanger; a part of carbon dioxide working medium flowing out of the low-temperature side outlet of the heat exchanger flows through the first turbine, the low-temperature side of the second regenerator and the third turbine; another part of the carbon dioxide working medium flows through the high-temperature side of the second regenerator and the second turbine; the carbon dioxide working medium flowing through the third turbine and the carbon dioxide working medium flowing through the second turbine are combined and then enter the high-temperature side of the first regenerator; the high-temperature side of the first regenerator is connected with the high-temperature side of the cooler; and the high-temperature side of the cooler is connected with the compressor. The application improves the supercritical carbon dioxide cycle power generation efficiency, does not increase the heat storage cost and improves the heat storage temperature difference.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of energy, and particularly relates to a supercritical carbon dioxide cycle power generation system, a working method thereof, and a solar thermal power generation system. BACKGROUND

[0002] The supercritical carbon dioxide power generation technology is generally considered to be the next generation of revolutionary power generation technology due to its high power generation efficiency, environmental protection, and no pollution. In the region above 600 DEG C, compared with the existing steam cycle power generation technology, the power generation efficiency can be generally improved by more than 10%, but the efficiency still has a large room for improvement.

[0003] Meanwhile, due to the higher power generation efficiency of supercritical carbon dioxide than steam cycle, it is generally considered to be suitable for the field of solar thermal power generation, so the improvement of the supercritical carbon dioxide cycle efficiency cannot be at the expense of the increase of the heat storage cost. SUMMARY

[0004] In view of the above technical problems, the present application provides a supercritical carbon dioxide cycle power generation system, a working method thereof, and a solar thermal power generation system, which improves the supercritical carbon dioxide cycle power generation efficiency, does not increase the heat storage cost, and improves the heat storage temperature difference.

[0005] To achieve the above-mentioned purposes, the technical scheme of the present application is as follows:

[0006] A supercritical carbon dioxide cycle power generation system, comprising: a compressor, a cooler, a first regenerator, a heat exchanger, a first turbine, a second regenerator, a second turbine, and a third turbine.

[0007] The compressor is connected to the low-temperature side inlet of the first regenerator, the low-temperature side outlet of the first regenerator is connected to the low-temperature side inlet of the heat exchanger, and one part of the carbon dioxide working medium flowing out of the low-temperature side outlet of the heat exchanger flows through the first turbine, the low-temperature side of the second regenerator, and the third turbine, and the other part flows through the high-temperature side of the second regenerator and the second turbine, and then merges with the carbon dioxide working medium flowing through the third turbine to enter the high-temperature side of the first regenerator, the high-temperature side of the first regenerator is connected to the high-temperature side of the cooler, and the high-temperature side of the cooler is connected to the compressor.

[0008] The system further comprises a fourth turbine, and the low-temperature side outlet of the heat exchanger is connected to the fourth turbine, and the carbon dioxide working medium passing through the fourth turbine is divided into two parts and enters the first turbine and the high-temperature side of the second regenerator, respectively.

[0009] The heat exchanger is a molten salt heat exchanger, and the high-temperature side of the molten salt heat exchanger flows through molten salt.

[0010] The cooler is a regenerator.

[0011] The application further provides a solar photo-thermal power generation system, comprising the supercritical carbon dioxide cycle power generation system and a heat storage system, and the high-temperature side of the heat exchanger of the supercritical carbon dioxide cycle power generation system is communicated with the heat storage system.

[0012] The working method of the supercritical carbon dioxide cycle power generation system comprises the following steps: carbon dioxide working medium is compressed to a low-temperature high-pressure state in a compressor, enters a low-temperature side of a first regenerator to absorb heat, then enters a low-temperature side of a heat exchanger to absorb heat of a heat storage medium, part of the high-temperature high-pressure state carbon dioxide working medium enters a first turbine, the high-pressure state carbon dioxide working medium does work in the first turbine to generate power, the carbon dioxide working medium flowing out of the first turbine is in a medium-low pressure state, then enters a low-temperature side of a second regenerator to absorb heat, and then enters a third turbine to do work and generate power; the other part of the high-temperature high-pressure state carbon dioxide working medium enters a high-temperature side of the second regenerator to release heat, then enters a second turbine to do work and generate power, and is combined with the carbon dioxide working medium entering the third turbine to flow into the high-temperature side of the first regenerator and the high-temperature side of a cooler to release heat in turn, and returns to the compressor.

[0013] Compared with the prior art, the application has the following advantages and positive effects:

[0014] In an embodiment of the application, the high-temperature high-pressure state carbon dioxide working medium absorbing heat of the heat exchanger is divided into two parts by using the fact that the work capacity of the turbine in a low-pressure region is higher than that in a high-pressure region, one part first enters the first turbine to do normal work, then enters the low-temperature side of the second regenerator to absorb heat, and then enters the third turbine to do work, because the temperature of the carbon dioxide working medium entering the third turbine is high due to the absorption of heat before entering the third turbine, and the third turbine is connected in series after the first turbine, the work capacity of the third turbine is higher than that of the first turbine; the other part enters the high-temperature side of the second regenerator to release heat, heats the carbon dioxide working medium flowing out of the first turbine, then enters the second turbine to do work and is combined with the carbon dioxide working medium flowing out of the third turbine, and enters the high-temperature side of the first regenerator.

[0015] Therefore, the fact that the work capacity of the supercritical carbon dioxide power generation turbine in a high-pressure region is weaker than that in a low-pressure region is used, the temperature of the carbon dioxide working medium entering the third turbine is increased by using the second regenerator, the work capacity of the third turbine is increased, the compression power of the compressor in the whole cycle is not affected, the second regenerator releases heat, the second turbine is connected in series, the temperature at the outlets of the second turbine and the third turbine is reduced, the inlet temperature of the heat exchanger is reduced, and the heat storage temperature difference is increased, so that the power generation efficiency and the heat storage temperature difference are improved without increasing the heat storage cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1Structure diagram of supercritical carbon dioxide cycle power generation system of embodiment 1 of the present application;

[0017] Figure 2 Structure diagram of supercritical carbon dioxide cycle power generation system of embodiment 2 of the present application

[0018] Reference numerals: 1-compressor; 2-first regenerator; 3-heat exchanger; 4-first turbine; 5-second turbine; 6-third turbine; 7-fourth turbine; 8-second regenerator; 9-cooler. DETAILED DESCRIPTION

[0019] The supercritical carbon dioxide cycle power generation system and working method and solar thermal power generation system according to the present application are further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present application will be more apparent according to the following description and claims.

[0020] Embodiment 1

[0021] Reference Figure 1 A supercritical carbon dioxide cycle system, comprising: a compressor 1, a cooler 9, a first regenerator 2, a heat exchanger 3, a first turbine 4, a second regenerator 8, a second turbine 5, a third turbine 6;

[0022] The compressor 1 is connected to the low-temperature side inlet of the first regenerator 2, the low-temperature side outlet of the first regenerator 2 is connected to the low-temperature side inlet of the heat exchanger 3, and a part of the carbon dioxide working medium flowing out of the low-temperature side outlet of the heat exchanger 3 flows through the first turbine 4, the low-temperature side of the second regenerator 8, and the third turbine 6, and another part of the carbon dioxide working medium flows through the high-temperature side of the second regenerator 8 and the second turbine 5, and then merges with the carbon dioxide working medium flowing through the third turbine 6 to enter the high-temperature side of the first regenerator 2, the high-temperature side of the first regenerator 2 is connected to the high-temperature side of the cooler 9, and the high-temperature side of the cooler 9 is connected to the compressor 1.

[0023] The heat exchanger 3 is a molten salt heat exchanger 3, and the high-temperature side of the molten salt heat exchanger 3 flows through molten salt. Of course, the high-temperature side of the heat exchanger 3 can also flow through other heat storage media, such as oil, or heat conducting oil, PCM, etc.

[0024] The above-mentioned cooler 9 is also a regenerator, and other media such as circulating water are used to reduce the temperature of the carbon dioxide working medium.

[0025] The working method of the supercritical carbon dioxide cycle system includes the following contents: carbon dioxide working medium is compressed to a low-temperature high-pressure state in a compressor 1, enters a first regenerator 2 to absorb heat at a low temperature, then enters a heat exchanger 3 to absorb heat of a heat storage medium at a low temperature, part of the high-temperature high-pressure state carbon dioxide working medium enters a first turbine 4, the high-pressure state carbon dioxide working medium does work to generate electricity in the first turbine 4, the carbon dioxide working medium flowing out of the first turbine 4 is in a medium-low pressure state, then enters a second regenerator 8 to absorb heat at a low temperature, and then enters a third turbine 6 to do work to generate electricity; the other part of the high-temperature high-pressure state carbon dioxide working medium enters the second regenerator 8 to release heat at a high temperature, then enters a second turbine 5 to do work to generate electricity, and is combined with the carbon dioxide working medium entering the third turbine 6 to flow into the first regenerator 2 at a high temperature, the cooler 9 at a high temperature in turn to release heat, and back to the compressor 1.

[0026] Embodiment 2

[0027] Referring to Figure 2 Further comprising a fourth turbine 7, the low-temperature side outlet of the heat exchanger 3 is communicated with the fourth turbine 7, and the carbon dioxide working medium passing through the fourth turbine 7 is divided into two parts to enter the first turbine 4 and the high-temperature side of the second regenerator 8 respectively.

[0028] In this embodiment, the carbon dioxide working medium flowing out of the heat exchanger 3 is first divided into two parts after passing through the fourth turbine 7, one part flows through the first turbine 4, the low-temperature side of the second regenerator 8, and the third turbine 6, and the other part flows through the high-temperature side of the second regenerator 8 and the second turbine 5, and is combined with the carbon dioxide working medium flowing out of the third turbine 6. The fourth turbine 7 is arranged, the first turbine 4 and the second turbine 5 do work in a medium-low pressure region of the carbon dioxide working medium, and the third turbine 6 does work in a lower pressure region, so that the work capacity of the first turbine 4, the second turbine 5 and the third turbine 6 is improved compared with Embodiment 1.

[0029] Embodiment 3

[0030] A solar thermal power generation system includes the supercritical carbon dioxide cycle power generation system of Embodiment 1 or Embodiment 2 and a heat storage system, and the high-temperature side of the heat exchanger 3 of the supercritical carbon dioxide cycle power generation system is communicated with the heat storage system. In the solar thermal system, the solar energy is converted into heat of the heat storage medium in the heat storage system by using a heliostat field and a heat absorber, and then the heat of the heat storage medium is transferred to the carbon dioxide working medium by using the heat exchanger 3, and the carbon dioxide working medium absorbing heat enters the fourth turbine 7 to do work to generate electricity, or is directly divided into two parts.

[0031] The embodiments of the present application are explained in detail above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments. Even if various changes are made to the present application, provided that the changes fall within the scope of the present application claims and equivalent technologies thereof, they still fall within the scope of the present application.

Claims

1. A supercritical carbon dioxide cycle power generation system, characterized in that, include: Compressor, cooler, first regenerator, heat exchanger, first turbine, second regenerator, second turbine, third turbine; The compressor is connected to the low-temperature side inlet of the first regenerator, and the low-temperature side outlet of the first regenerator is connected to the low-temperature side inlet of the heat exchanger. A portion of the carbon dioxide working fluid flowing out from the low-temperature side outlet of the heat exchanger flows through the first turbine, the low-temperature side of the second regenerator, and the third turbine, while another portion flows through the high-temperature side of the second regenerator and the second turbine. After merging with the carbon dioxide working fluid flowing through the third turbine, it enters the high-temperature side of the first regenerator. The high-temperature side of the first regenerator is connected to the high-temperature side of the cooler, and the high-temperature side of the cooler is connected to the compressor.

2. The supercritical carbon dioxide cycle power generation system according to claim 1, characterized in that, It also includes a fourth turbine, the low-temperature side outlet of the heat exchanger is connected to the fourth turbine, and the carbon dioxide working fluid passing through the fourth turbine is divided into two parts and enters the high-temperature side of the first turbine and the second regenerator respectively.

3. The supercritical carbon dioxide cycle power generation system according to claim 1 or 2, characterized in that, The heat exchanger is a molten salt heat exchanger, and molten salt flows through the high-temperature side of the molten salt heat exchanger.

4. A solar thermal power generation system, characterized in that, The system includes the supercritical carbon dioxide cycle power generation system and the thermal storage system as described in any one of claims 1-3, wherein the high-temperature side of the heat exchanger of the supercritical carbon dioxide cycle power generation system is connected to the thermal storage system.

5. A method for operating a supercritical carbon dioxide cycle power generation system as described in any one of claims 1-3, characterized in that, The carbon dioxide working fluid is compressed to a low-temperature, high-pressure state in the compressor, enters the low-temperature side of the first regenerator to absorb heat, and then enters the low-temperature side of the heat exchanger to absorb heat from the heat storage medium. A portion of the high-temperature, high-pressure carbon dioxide working fluid enters the first turbine, where it performs work and generates electricity. The carbon dioxide working fluid flowing out of the first turbine is in a medium-to-low-pressure state, then enters the low-temperature side of the second regenerator to absorb heat, and then enters the third turbine to perform work and generate electricity. Another portion of the high-temperature, high-pressure carbon dioxide working fluid enters the high-temperature side of the second regenerator to release heat, and then enters the second turbine to perform work and generate electricity. It then merges with the carbon dioxide working fluid entering the third turbine and flows sequentially into the high-temperature side of the first regenerator and the high-temperature side of the cooler to release heat, before returning to the compressor.

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