A supercritical Brayton cycle power generation system and method with split flow throttling cooling

Abstract

The present invention discloses a supercritical Brayton cycle power generation system and method with shunt throttling cooling, the system comprises a heat source, a supercritical Brayton cycle system, a cooling tower and a CO2 compressor intermediate shunt throttling refrigeration system connected in sequence; the present invention effectively controls the temperature of the working fluid entering the CO2 compressor through the refrigeration system, so that the cold end temperature of the supercritical Brayton cycle power generation system can also be cooled to a lower level during high temperatures in summer, maintaining stable and reliable operation of the system. In addition, the existing equipment in the system is utilized to the maximum extent, saving costs.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation systems, and in particular to a supercritical Brayton cycle power generation system and method with split flow throttling cooling. Background Art

[0002] Under the background of energy shortage and environmental crisis, people pay more and more attention to improving energy utilization. Among many thermodynamic cycles, supercritical Brayton cycle is the most advantageous cycle. New supercritical working fluids (carbon dioxide, helium and nitrous oxide, etc.) have inherent advantages such as high energy density, high heat transfer efficiency and simple system. They can greatly improve the heat-to-work conversion efficiency, reduce the size of equipment and have high economy.

[0003] However, this type of cycle also has an obvious technical difficulty, namely the cooling problem. The supercritical cycle, especially the supercritical cycle like carbon dioxide, has a critical temperature close to the ambient temperature (31°C). When the cold end temperature is low, the compression power consumption is small and the thermal efficiency is very high. However, it is very sensitive to the cold end temperature. After slightly exceeding the designed cold end temperature, its thermal efficiency will drop significantly. Therefore, its cold end temperature, that is, the compressor inlet temperature, must be controlled very accurately. However, in summer, it is difficult to cool to the required cold end temperature in a large area of ​​China, which will greatly affect its efficiency and thus affect the promotion of this technology.

[0004] This problem can be solved by further refrigeration. Generally speaking, the average summer temperature in most parts of China is still below 40℃. If it needs to be further cooled to below the design cooling temperature, the temperature required to be lowered is not large, and the cooling capacity will not be too large.

[0005] High-pressure CO2 throttling is also a common refrigeration method. It uses the system's own CO2 compressor to extract a portion of the CO2 gas from the middle stage of the compressor for refrigeration and cool the mainstream CO2 working fluid, making maximum use of the system's own equipment while also being able to control the system's cold-end temperature requirements. Summary of the invention

[0006] In order to overcome the above-mentioned deficiencies of the prior art, the object of the present invention is to provide a supercritical Brayton cycle power generation system and method with split-flow throttling cooling, which adopts a method with relatively low technical difficulty and high feasibility to improve the thermal efficiency of the system.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A supercritical Brayton cycle power generation system with split throttling cooling, comprising a turbine 2, the inlet of the turbine 2 is connected to the outlet of the working medium side of a heat source 1, the outlet of the turbine 2 is connected to the inlet of the heat release side of a high-temperature regenerator 3, the outlet of the heat release side of the high-temperature regenerator 3 is connected to the inlet of the heat release side of a low-temperature regenerator 4, the outlet of the heat release side of the low-temperature regenerator 4 is split into two paths, one of which is connected to the inlet of the working medium side of a precooler 6, the outlet of the working medium side of the precooler 6 is connected to an inlet of a mixer 7, the outlet of the mixer 7 is connected to the inlet of a main compressor 8, and the outlet of the main compressor 8 is divided into a final outlet and a middle outlet. There are two intermediate stage outlets, the last stage is connected to the inlet of the heat absorption side of the low-temperature regenerator 4, the other outlet branched off from the heat release side outlet of the low-temperature regenerator 4 is connected to the inlet of the re-compressor 5, the outlet of the re-compressor 5 is connected to the inlet of the heat absorption side of the high-temperature regenerator 3 after merging with the working fluid at the outlet of the heat absorption side of the low-temperature regenerator 4, the outlet of the heat absorption side of the high-temperature regenerator 3 is connected to the inlet of the heat source 1, the intermediate stage outlet of the main compressor 8 is connected to the inlet of the working fluid side of the bypass cooler 9, the working fluid side outlet of the bypass cooler 9 is connected to the inlet of the throttling nozzle 10, and the outlet of the throttling nozzle 10 is connected to another inlet of the mixer 7.

[0009] The heat source 1 is a boiler, a waste heat exchanger or solar energy.

[0010] A supercritical Brayton cycle power generation method with split-flow throttling cooling, when the ambient temperature is not very high (less than or equal to 30 degrees Celsius in water-rich areas; less than or equal to 24 degrees Celsius in water-deficient areas), the working medium can be cooled to the required temperature by directly cooling the cooling tower, the supercritical working medium heated by the heat source 1 enters the turbine system 2 to do work, and the high-temperature low-pressure exhaust steam after doing work enters the high-temperature regenerator 3 and the heat release side of the low-temperature regenerator 4 in turn to release heat, and the low-temperature low-pressure working medium after heat release is divided into two paths, one of which enters the working medium side of the precooler 6 After being cooled, it enters the re-compressor 5. The high-pressure working fluid after being pressurized enters the heat absorption side of the high-temperature regenerator 3 to absorb heat. The second working fluid branched from the outlet of the heat release side of the low-temperature regenerator 4 directly enters the pre-cooler 6. After being cooled, it enters the mixer 7 and then enters the main compressor 8. After being compressed, it enters the heat absorption side of the low-temperature regenerator 4 to absorb heat, and then merges with the first working fluid compressed by the re-compressor, and then enters the heat absorption side of the high-temperature regenerator 3. After absorbing heat in the high-temperature regenerator 3, it enters the heat source 1 to be heated, completing the entire working fluid circulation process;

[0011] When the ambient temperature is high in summer (above 30 degrees Celsius in water-rich areas and above 24 degrees Celsius in water-scarce areas), the conventional cooling method cannot cool the working fluid to the required temperature. The working fluid is extracted from the intermediate stage outlet of the main compressor 8 and enters the bypass cooler 9 to be cooled, and then enters the throttling nozzle 10 to reduce the pressure and further reduce the temperature. The low-temperature working fluid enters the other inlet of the mixer 7, mixes with the mainstream and reduces the mainstream temperature before entering the main compressor 8, thereby controlling the mainstream cooling temperature.

[0012] Beneficial effects of the present invention:

[0013] The supercritical Brayton cycle power generation system and method with shunt throttling cooling can effectively solve the heat dissipation problem when the ambient temperature of the thermal system is high, ensure the system cold end temperature, and guarantee the system thermal efficiency.

[0014] After adopting refrigeration and cooling technology, the cold end temperature of the supercritical Brayton cycle can be effectively maintained and can be stably maintained near the critical point to maintain system stability. After adopting refrigeration and cooling technology, the supercritical Brayton cycle power generation system has stronger environmental adaptability, especially in areas with high temperatures in summer. The CO2 compressor intermediate stage shunt throttling refrigeration technology is adopted to make the most of the existing equipment of the system without adding any new working fluids. It is the simplest refrigeration method. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the system of the present invention.

[0016] Among them, heat source 1, turbine 2, high temperature regenerator 3, low temperature regenerator 4, recompressor 5, precooler 6, mixer 7, main compressor 8, split cooler 9, throttling nozzle 10 DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with embodiments.

[0018] like Figure 1 As shown, a supercritical Brayton cycle power generation system and method with split-flow throttling cooling includes a heat source 1, a turbine 2, a high-temperature regenerator 3, a low-temperature regenerator 4, a recompressor 5, a precooler 6, a mixer 7, a main compressor 8, a split-flow cooler 9 and a throttling nozzle 10 connected in sequence.

[0019] The inlet of turbine 2 is connected to the outlet of working medium side of heat source 1, the outlet of turbine 2 is connected to the inlet of heat release side of high temperature regenerator 3, the outlet of heat release side of high temperature regenerator 3 is connected to the inlet of heat release side of low temperature regenerator 4, the outlet of heat release side of low temperature regenerator 4 is split into two paths, one of which is connected to the inlet of working medium side of precooler 6, the outlet of working medium side of precooler 6 is connected to an inlet of mixer 7, the outlet of mixer 7 is connected to the inlet of main compressor 8, the outlet of main compressor 8 is divided into two paths, the outlet of final stage and the outlet of intermediate stage, the outlet of final stage is connected to the inlet of low temperature regenerator 4, the outlet of intermediate stage is connected to the inlet of main compressor 8, the outlet of intermediate stage is connected to the inlet of main compressor 8, the outlet of intermediate stage is connected to the inlet of main compressor 8, the outlet of intermediate stage is connected to the inlet of low temperature regenerator 4, the outlet of intermediate stage is connected to the inlet of low temperature regenerator 4, the outlet of intermediate stage is connected to the inlet of main compressor 8 ... The inlet of the heat absorption side of the regenerator 4 is connected, the other path branched off from the outlet of the heat release side of the low-temperature regenerator 4 is connected to the inlet of the re-compressor 5, the outlet of the re-compressor 5 merges with the outlet working medium of the heat absorption side of the low-temperature regenerator 4 and is connected to the inlet of the heat absorption side of the high-temperature regenerator 3, the outlet of the heat absorption side of the high-temperature regenerator 3 is connected to the inlet of the heat source 1, the intermediate stage outlet of the main compressor 8 is connected to the inlet of the working medium side of the split cooler 9, the outlet of the working medium side of the split cooler 9 is connected to the inlet of the throttling nozzle 10, and the outlet of the throttling nozzle 10 is connected to another inlet of the mixer 7.

[0020] The heat source 1 is a boiler, a waste heat exchanger or solar energy.

[0021] Working principle of the present invention:

[0022] A supercritical Brayton cycle power generation method with split throttling cooling, when the ambient temperature is not very high and the working medium can be cooled to the required temperature by directly cooling the cooling tower, the supercritical working medium heated by the heat source 1 enters the turbine system 2 to do work, and the high-temperature low-pressure exhaust steam after doing work enters the heat release side of the high-temperature regenerator 3 and the low-temperature regenerator 4 in turn to release heat, and the low-temperature low-pressure working medium after releasing heat is divided into two paths, one path enters the working medium side of the precooler 6 to be cooled, and the other path enters the recompressor 5, and the high-pressure working medium after being pressurized enters the heat absorption side of the high-temperature regenerator 3 to absorb heat, and the second path of working medium split from the outlet of the heat release side of the low-temperature regenerator 4 directly enters the precooler 6, enters the mixer 7 after being cooled, and then enters the main compressor 8, and after being compressed, it merges with the first path of working medium compressed by the recompressor, and then enters the heat absorption side of the high-temperature regenerator 3, and after absorbing heat in the high-temperature regenerator 3, enters the heat source 1 to be heated, completing the entire working medium cycle process;

[0023] When the ambient temperature is high in summer, the conventional cooling method cannot cool the working fluid to the required temperature. The working fluid is extracted from the intermediate stage outlet of the main compressor 8 and enters the bypass cooler 9 to be cooled, and then enters the throttling nozzle 10 to reduce the pressure and further reduce the temperature. The low-temperature working fluid enters the other inlet of the mixer 7, mixes with the mainstream and reduces the mainstream temperature before entering the main compressor 8, which plays a role in controlling the mainstream cooling temperature.

[0024] but Figure 1Other layouts of the supercritical Brayton cycle system shown do not affect the application of the present invention, and the content of the present invention is also applicable to other layouts of the supercritical cycle system. Therefore, the supercritical Brayton cycle system in the present invention is a supercritical Brayton cycle system in a broad sense, and is not limited to the layout shown in the figure. For example, other supercritical Brayton cycle systems may use a multi-stage turbine system, or a turbine system with reheat, or may not use a split recompression system, that is, only one main compressor is used without a recompressor in the figure, and the two regenerators in the figure are combined into one regenerator, and so on.

[0025] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A supercritical Brayton cycle power generation method with split-flow throttling cooling, when the ambient temperature is not very high and the working medium can be cooled to a required temperature by directly cooling the working medium through a cooling tower, the supercritical working medium heated by a heat source (1) enters a turbine system to perform work, and the high-temperature low-pressure exhaust steam after the work enters the heat release side of a high-temperature regenerator (3) and a low-temperature regenerator (4) in turn to release heat, and the low-temperature low-pressure working medium after the heat release is divided into two paths, one path enters a precooler (6) to be cooled on the working medium side, and the other path enters a recompressor (5) to be pressurized by a high-pressure regenerator (6). The compressed working fluid enters the heat absorbing side of the high-temperature regenerator (3) to absorb heat, and the second working fluid branched from the outlet of the heat releasing side of the low-temperature regenerator (4) directly enters the precooler (6), is cooled, enters the mixer (7), and then enters the main compressor (8), is compressed, and then merges with the first working fluid compressed by the recompressor after entering the heat absorbing side of the low-temperature regenerator (4) to absorb heat, and then enters the heat absorbing side of the high-temperature regenerator (3), absorbs heat in the high-temperature regenerator (3), and then enters the heat source (1) to be heated, completing the entire working fluid circulation process; When the ambient temperature is high in summer, the conventional cooling method cannot cool the working fluid to the required temperature. The working fluid is drawn from the intermediate outlet of the main compressor (8) and enters the split cooler (9) to be cooled, and then enters the throttling nozzle (10) to reduce the pressure and further reduce the temperature. The low-temperature working fluid enters another inlet of the mixer (7), mixes with the mainstream and reduces the mainstream temperature before entering the main compressor (8), thereby controlling the mainstream cooling temperature. The method is implemented by the following system: the system comprises a turbine (2), the inlet of the turbine (2) is connected to the outlet of the working medium side of the heat source (1), the outlet of the turbine (2) is connected to the inlet of the heat release side of the high-temperature regenerator (3), the outlet of the heat release side of the high-temperature regenerator (3) is connected to the inlet of the heat release side of the low-temperature regenerator (4), the outlet of the heat release side of the low-temperature regenerator (4) is split into two paths, one of which is connected to the inlet of the working medium side of the precooler (6), the outlet of the working medium side of the precooler (6) is connected to an inlet of a mixer (7), the outlet of the mixer (7) is connected to the inlet of a main compressor (8), and the outlet of the main compressor (8) is divided into a final-stage outlet and an intermediate-stage outlet. Two paths, the last stage is connected to the inlet of the heat absorption side of the low-temperature regenerator (4), the other path branched from the outlet of the heat release side of the low-temperature regenerator (4) is connected to the inlet of the recompressor (5), the outlet of the recompressor (5) is connected to the inlet of the heat absorption side of the high-temperature regenerator (3) after the working fluid at the outlet of the heat absorption side of the low-temperature regenerator (4) is merged, the outlet of the heat absorption side of the high-temperature regenerator (3) is connected to the inlet of the heat source (1), the outlet of the middle stage of the main compressor (8) is connected to the inlet of the working fluid side of the split cooler (9), the outlet of the working fluid side of the split cooler (9) is connected to the inlet of the throttling nozzle (10), and the outlet of the throttling nozzle (10) is connected to another inlet of the mixer (7); The heat source (1) is a boiler, a waste heat exchanger or solar energy.

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