阅读说明：本技术 一种超临界布雷顿循环旁路除杂质系统及方法 (Supercritical Brayton cycle bypass impurity removal system and method ) 是由 高炜 李红智 张一帆 姚明宇 杨玉 张纯 于 2020-05-26 设计创作，主要内容包括：一种超临界布雷顿循环旁路除杂质系统及方法,该系统包括依次连通的热源、超临界布雷顿循环系统、除杂质旁路和CO2压缩机中间级分流节流制冷系统；该除杂质系统为超临界CO2发电系统服务,旨在排除系统中的气体杂质,提高系统中CO2纯度,保证系统性能,该系统利用压缩机中间级抽气自身降温形成低温冷却工质,再利用这部分工质冷却旁路中的低压CO2工质使其成为液体,旁路中的液体CO2在分离器中将系统中混入O2、N2等杂质气体分流并排除,除杂质旁路不必时时运行,只在检测到系统杂质含量过高时运行。该系统最大程度上利用了CO2系统自身设备,不必添加复杂的化学系统及化学药剂,降低了除杂质过程的投资以及运行费用,维护超临界CO2发电系统工质纯净度。(A supercritical Brayton cycle bypass impurity removal system and a method thereof are provided, the system comprises a heat source, a supercritical Brayton cycle system, an impurity removal bypass and a CO2 compressor intermediate-stage shunting throttling refrigeration system which are sequentially communicated; the impurity removal system serves a supercritical CO2 power generation system, aims to remove gas impurities in the system, improves the purity of CO2 in the system and ensures the performance of the system, and utilizes the middle-stage air exhaust of a compressor to cool to form a low-temperature cooling working medium, and then utilizes the part of the working medium to cool a low-pressure CO2 working medium in a bypass to enable the low-pressure CO2 working medium to become liquid, the liquid CO2 in the bypass shunts and removes impurity gases such as O2 and N2 mixed in the system in a separator, and the impurity removal bypass does not need to operate all the time and only operates when the impurity content of the system is detected to be too high. The system utilizes the self equipment of the CO2 system to the maximum extent, does not need to add a complex chemical system and chemical agents, reduces the investment and the operating cost in the impurity removal process, and maintains the working medium purity of the supercritical CO2 power generation system.)

1. A supercritical Brayton cycle bypass impurity removal system is characterized by comprising a turbine (2), wherein an inlet of the turbine (2) is communicated with a working medium side outlet of a heat source (1), an outlet of the turbine (2) is communicated with a heat release side inlet of a high-temperature heat regenerator (3), a heat release side outlet of the high-temperature heat regenerator (3) is communicated with a heat release side inlet of a low-temperature heat regenerator (4), a heat release side outlet of the low-temperature heat regenerator (4) is divided into two paths, one path is communicated with an inlet of a recompressor (5), an outlet of the recompressor (5) is communicated with a heat absorption side inlet of the high-temperature heat regenerator (3) after being converged with a heat absorption side outlet working medium of the low-temperature heat regenerator (4), a working medium path from a heat release side outlet of the low-temperature heat regenerator (4) is communicated with another working medium side inlet of a precooler (6), and a working medium side outlet of the precooler (6) is, the outlet of the bypass throttling pressure reducer (7) is communicated with the hot side inlet of a bypass cooler (8), the hot side outlet of the bypass cooler (8) is communicated with the upper inlet of a gas-liquid separation tower (9), the lower outlet of the gas-liquid separation tower (9) is communicated with the inlet of a booster pump (10), the outlet of the booster pump (10) is communicated with the bypass side inlet of a filtering bypass mixer (11), the main flow of the working medium side outlet of a precooler (6) is communicated with the main flow inlet of the filtering bypass mixer (11), the outlet of the filtering bypass mixer (11) is communicated with the main flow inlet of a cooling bypass mixer (12), the outlet of the cooling bypass mixer (12) is communicated with the inlet of a main compressor (13), the middle-stage air exhaust bypass outlet of the main compressor is communicated with the working medium side inlet of a cooling bypass cooler (14), the working medium side outlet of the cooling bypass cooler (14) is communicated with the inlet of a cooling throttling bypass pressure reducer (15), the outlet of the cooling bypass throttling pressure reducer (15) is communicated with the cold side inlet of the bypass cooler (8), the cold side outlet of the bypass cooler (8) is communicated with the bypass side inlet of the cooling bypass mixer (12), the main compressor (13) is divided into a final stage main path outlet which is communicated with the heat absorption side inlet of the low-temperature heat regenerator (4), the heat absorption side outlet working medium of the low-temperature heat regenerator (4) is communicated with the heat absorption side inlet of the high-temperature heat regenerator (3) after the working medium of the compressor outlet is converged, and the heat absorption side outlet of the high-temperature heat regenerator (3) is communicated with the inlet of the heat source (1).

2. The supercritical brayton cycle bypass impurity removal system according to claim 1, wherein a liquid outlet is provided at the middle lower part of said gas-liquid separation column 9, and an exhaust port is provided at the upper part of said gas-liquid separation column 9.

3. The supercritical brayton cycle bypass impurity removal system of claim 1 wherein said heat source 1 is a boiler, waste heat exchanger or solar energy.

4. A method for removing impurities by a supercritical Brayton cycle bypass is characterized by comprising the following steps;

the impurity removal system aims at maintaining the purity of CO2 in the system, does not need to be started and operated all the time, and only needs to be started and operated when the content of impurity gases such as O2, N2 and the like in the system exceeds the standard;

when the purity of CO2 in the system is enough, supercritical CO2 in the system is firstly heated by a heat source (1), then supercritical working medium enters a turbine system (2) to do work, high-temperature low-pressure exhaust steam after doing work sequentially enters a high-temperature heat regenerator (3) and the heat release side of a low-temperature heat regenerator (4) to release heat, low-temperature low-pressure working medium after releasing heat is divided into two paths, one path of low-temperature low-pressure working medium enters a precooler (6) to be cooled, the other path of high-pressure working medium enters a recompressor (5), pressurized high-pressure working medium enters a high-temperature heat regenerator (3) to absorb heat, a second path of working medium which is branched from the outlet of the heat release side of the low-temperature heat regenerator (4) directly enters the precooler (6), all the cooled working medium sequentially passes through a filtering bypass mixer (11) and a cooling bypass mixer (12), then enters a main compressor (13), flows out from the main compressor after being compressed, then the mixed gas is converged with a first path of working medium compressed by a recompressor, enters a heat absorption side of a high-temperature heat regenerator (3), absorbs heat in the high-temperature heat regenerator (3), and then enters a heat source (1) to be heated, so that the whole working medium circulation flow is completed;

when the content of O2, N2 and other impurity gases in the system exceeds standard, the operation impurity-removing bypass and the shunt throttling cooling bypass need to be opened, and the difference from the normal operation is that after CO2 working medium flows out from a precooler (6), a part of working medium is shunted and enters the impurity-removing bypass, the working medium in the bypass firstly enters a bypass throttling decompressor (7) for pressure reduction and throttling, the pressure is reduced to be below the critical point of CO2, the working medium is in a subcritical state and then enters a bypass cooler (8), the subcritical CO2 working medium is further cooled to the saturation temperature or a liquid state slightly lower than the saturation temperature, the impurity gases N2 and O2 still keep a gas state due to lower liquefaction temperature, then the liquid CO2 working medium and the impurity gases enter a gas-liquid separation tower (9), the liquid CO2 flows out from a liquid outlet at the lower part in the gas-liquid separation tower (9), and the gaseous impurities such as N2, O2 and the like are discharged from an exhaust port at the, pure subcritical CO2 liquid working medium after impurity removal flows into a booster pump (10), the pressure is increased to a supercritical state and then enters a filtering bypass mixer (11) to be mixed with a main flow from a precooler (6), then the mixture enters a main compressor (13) through a cooling bypass mixer (12), at the moment, a middle-stage air suction bypass of the main compressor (13) is opened, a part of working medium compressed to a certain pressure flows into a shunting throttling cooling bypass from an air suction outlet, firstly enters a cooling bypass cooler (14) to be primarily cooled, then enters a cooling bypass throttling decompressor (15), is further reduced to a low temperature lower than the liquefaction temperature of CO2 in the front impurity removal bypass after being subjected to pressure reduction and throttling, then is introduced into a low-temperature side of a bypass cooler (8) to cool an impurity removal bypass working medium, then the cooling bypass working medium inlet cooling bypass mixer (12) is mixed with the main flow and then enters the main compressor (13), the other operation processes of the system are the same as the normal operation.

Technical Field

The invention relates to the technical field of power generation systems, in particular to a supercritical Brayton cycle bypass impurity removal system and a supercritical Brayton cycle bypass impurity removal method.

Background

Under the large background of energy shortage and environmental crisis, increasing attention is paid to improving energy utilization rate. The supercritical brayton cycle is currently the most advantageous form of cycle among the many thermodynamic cycles. The novel supercritical working medium (carbon dioxide, helium, dinitrogen oxide and the like) has the inherent advantages of high energy density, high heat transfer efficiency, simple system and the like, can greatly improve the heat-work conversion efficiency, reduces the equipment volume and has very high economical efficiency.

However, the circulation also has an obvious technical difficulty, the supercritical carbon dioxide brayton circulation adopts carbon dioxide as work instead of water, the usage amount of the carbon dioxide in the circulation system is large, the purity requirement is high, and generally industrial carbon dioxide is used, so a certain initial investment is needed. However, for large industrial-grade systems, it is difficult to maintain the purity of carbon dioxide in the system high for a long time without mixing or remaining other impurity gases, and therefore, it is necessary to continuously purify carbon dioxide in the system for a long time to ensure the purity of carbon dioxide, thereby ensuring the performance of the system. However, since CO2 in the system is in a supercritical state and has no phase change, it is difficult to separate from N2 and O2, and if a chemical reaction is used to remove N2 and O2, it is complicated, and it is not easy to ensure that other chemical elements are not mixed, and N2 is an inert gas, and it is difficult to separate by a chemical method.

The conventional steam Rankine cycle equipment with the deaerator can remove oxygen in the system, but the steam Rankine cycle is premised on the fact that liquid water exists and can separate gas from liquid water, and the supercritical CO2 system is liquid-free and is a supercritical working medium.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a supercritical Brayton cycle bypass impurity removal system and a supercritical Brayton cycle bypass impurity removal method, wherein N2 and O2 impurities are removed by utilizing the working medium characteristics of the system and utilizing the equipment of the system to the maximum extent, and the thermal efficiency of the system is improved by adopting a method with relatively low technical difficulty and high feasibility.

In order to achieve the purpose, the invention adopts the technical scheme that:

a supercritical Brayton cycle bypass impurity removal system comprises a turbine 2, wherein an inlet of the turbine 2 is communicated with a working medium side outlet of a heat source 1, an outlet of the turbine 2 is communicated with a heat release side inlet of a high-temperature heat regenerator 3, a heat release side outlet of the high-temperature heat regenerator 3 is communicated with a heat release side inlet of a low-temperature heat regenerator 4, the heat release side outlet of the low-temperature heat regenerator 4 is divided into two paths, one path is communicated with an inlet of a recompressor 5, an outlet of the recompressor 5 is communicated with a heat absorption side inlet of the high-temperature heat regenerator 3 after being converged with a heat absorption side outlet working medium of the low-temperature heat regenerator 4, the other path from the heat release side outlet of the low-temperature heat regenerator 4 is communicated with a working medium side inlet of a precooler 6, the working medium side outlets of the precooler 6 are divided into two paths, a bypass is communicated with an, the hot side outlet of the bypass cooler 8 is communicated with the upper inlet of the gas-liquid separation tower 9, the lower outlet of the gas-liquid separation tower 9 is communicated with the inlet of the booster pump 10, the outlet of the booster pump 10 is communicated with the bypass side inlet of the filtering bypass mixer 11, the main flow of the working medium side outlet of the precooler 6 is communicated with the main flow inlet of the filtering bypass mixer 11, the outlet of the filtering bypass mixer 11 is communicated with the main flow inlet of the cooling bypass mixer 12, the outlet of the cooling bypass mixer 12 is communicated with the inlet of the main compressor 13, the middle stage air exhaust bypass outlet of the main compressor 13 is communicated with the working medium side inlet of the cooling bypass cooler 14, the working medium side outlet of the cooling bypass cooler 14 is communicated with the inlet of the cooling bypass throttling pressure reducer 15, the outlet of the cooling bypass pressure reducer 15 is communicated with the cold side inlet of the bypass cooler 8, the cold side outlet of the bypass cooler 8 is communicated with, the main compressor 13 is divided into a final stage main path outlet communicated with the heat absorption side inlet of the low temperature heat regenerator 4, the heat absorption side outlet working medium of the low temperature heat regenerator 4 is communicated with the heat absorption side inlet of the high temperature heat regenerator 3 after the outlet working medium of the compressor is converged, and the heat absorption side outlet of the high temperature heat regenerator 3 is communicated with the inlet of the heat source 1.

The middle lower part of the gas-liquid separation tower 9 is provided with a liquid outlet, and the upper part of the gas-liquid separation tower 9 is provided with an exhaust port.

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

A method for removing impurities by a supercritical Brayton cycle bypass comprises the following steps;

the impurity removal system aims at maintaining the purity of CO2 in the system, does not need to be started and operated all the time, and only needs to be started and operated when the content of impurity gases such as O2, N2 and the like in the system exceeds the standard;

when the purity of CO2 in the system is enough, supercritical CO2 in the system is firstly heated by a heat source 1, then supercritical working medium enters a turbine system 2 to do work, high-temperature low-pressure exhaust steam after doing work sequentially enters the heat release sides of a high-temperature heat regenerator 3 and a low-temperature heat regenerator 4 to release heat, low-temperature low-pressure working medium after releasing heat is divided into two paths, one path enters the working medium side of a precooler 6 to be cooled, the other path enters a recompressor 5, pressurized high-pressure working medium enters the heat absorption side of the high-temperature heat regenerator 3 to absorb heat, all working medium after being cooled by the precooler 6 sequentially passes through a filtering bypass mixer 11 and a cooling bypass mixer 12, then enters a main compressor 13, flows out from the last stage of the main compressor after being compressed, enters the heat absorption side of the low-temperature heat regenerator 4 to absorb heat, then is converged with the working medium compressed by a recompressor 5, then enters the heat absorption side of the high-temperature, completing the whole working medium circulation process;

when the content of O2, N2 and other impurity gases in the system exceeds standard, the operation impurity-removing bypass and the shunt throttling cooling bypass need to be opened, and the difference from the normal operation is that after CO2 working medium flows out from the precooler 6, a part of working medium is shunted and enters the impurity-removing bypass, the working medium in the bypass firstly enters the bypass throttling decompressor 7 to reduce the pressure and throttle, the pressure is reduced to be below the critical point of CO2, the working medium is in a subcritical state, then enters the bypass cooler 8, the subcritical CO2 working medium is further cooled to the saturation temperature or a liquid state slightly lower than the saturation temperature, the impurity gases N2 and O2 still keep a gaseous state due to lower liquefaction temperature, then the liquid CO2 working medium and the impurity gases enter the gas-liquid separation tower 9, the liquid CO2 flows out from a liquid outlet at the lower part in the gas-liquid separation tower 9, the gaseous impurities such as N2, O2 and the like are discharged from an exhaust port at the upper part of the separation tower 9, and the pure subcritical CO2, the pressure is increased to a supercritical state, then the mixture enters a filtering bypass mixer 11 to be mixed with a main flow from a precooler 6, then the mixture enters a main compressor 13 after passing through a cooling bypass mixer 12, at the moment, a middle-stage air suction bypass of the main compressor 13 is opened, a part of working medium compressed to a certain pressure flows into a flow dividing throttling cooling bypass from an air suction outlet, firstly the working medium enters a cooling bypass cooler 14 to be primarily cooled, then enters a cooling bypass throttling decompressor 15, is subjected to pressure reduction and throttling and then further reduced to a low temperature lower than the liquefaction temperature of CO2 in the previous impurity removing bypass, then the working medium is introduced into the low temperature side of a bypass cooler 8 to cool the impurity removing bypass working medium, then the cooling bypass mixer 12 at a cooling bypass inlet is mixed with the main flow and then enters the main compressor 13, and other operation processes of the system are the same.

The invention has the beneficial effects that:

the method extracts a part of working medium from the position closest to a critical point in a supercritical CO2 system, firstly reduces the pressure of the working medium to a subcritical state close to critical pressure, then reduces the temperature of the working medium to liquefy the working medium, and then separates out gas impurities in the working medium. The cooling working medium for cooling the part of the working medium is also CO2 in the system, the part of CO2 is extracted from the middle stage of a compressor in the system, the part of the extracted gas is firstly cooled and precooled and then throttled for further cooling, and the part of CO2 can be cooled to a temperature lower than the required liquefaction temperature of CO2 while keeping a supercritical state, so that the temperature of CO2 bypassing impurities can be cooled and liquefied.

The invention can effectively remove N2 and O2 in the system on the premise of utilizing the equipment of the system to the maximum extent, reducing the energy consumption as much as possible and not adding any additional chemical agent, thereby maintaining the purity of the system and ensuring the performance of the system.

Drawings

FIG. 1 is a schematic diagram of the system of the present invention.

Wherein, the heat source 1, the turbine 2, the high temperature heat regenerator 3, the low temperature heat regenerator 4, the recompressor 5, the precooler 6, the bypass throttling pressure reducer 7, the bypass cooler 8, the gas-liquid separation tower 9, the booster pump 10, the filtration bypass mixer 11, the cooling bypass mixer 12, the main compressor 13, the cooling bypass cooler 14, the cooling bypass throttling pressure reducer 15

Detailed Description

The present invention will be described in further detail with reference to examples.

As shown in fig. 1: a supercritical Brayton cycle bypass impurity removal system comprises a turbine 2, wherein an inlet of the turbine 2 is communicated with a working medium side outlet of a heat source 1, an outlet of the turbine 2 is communicated with a heat release side inlet of a high-temperature heat regenerator 3, a heat release side outlet of the high-temperature heat regenerator 3 is communicated with a heat release side inlet of a low-temperature heat regenerator 4, the heat release side outlet of the low-temperature heat regenerator 4 is divided into two paths, one path is communicated with an inlet of a recompressor 5, an outlet of the recompressor 5 is communicated with a heat absorption side inlet of the high-temperature heat regenerator 3 after being converged with a heat absorption side outlet working medium of the low-temperature heat regenerator 4, the other path from the heat release side outlet of the low-temperature heat regenerator 4 is communicated with a working medium side inlet of a precooler 6, the working medium side outlets of the precooler 6 are divided into two paths, a bypass is communicated with an, the hot side outlet of the bypass cooler 8 is communicated with the upper inlet of the gas-liquid separation tower 9, the lower outlet of the gas-liquid separation tower 9 is communicated with the inlet of the booster pump 10, the outlet of the booster pump 10 is communicated with the bypass side inlet of the filtering bypass mixer 11, the main flow of the working medium side outlet of the precooler 6 is communicated with the main flow inlet of the filtering bypass mixer 11, the outlet of the filtering bypass mixer 11 is communicated with the main flow inlet of the cooling bypass mixer 12, the outlet of the cooling bypass mixer 12 is communicated with the inlet of the main compressor 13, the middle stage air exhaust bypass outlet of the main compressor 13 is communicated with the working medium side inlet of the cooling bypass cooler 14, the working medium side outlet of the cooling bypass cooler 14 is communicated with the inlet of the cooling bypass throttling pressure reducer 15, the outlet of the cooling bypass pressure reducer 15 is communicated with the cold side inlet of the bypass cooler 8, the cold side outlet of the bypass cooler 8 is communicated with, the main compressor 13 is divided into a final stage main path outlet communicated with the heat absorption side inlet of the low temperature heat regenerator 4, the heat absorption side outlet working medium of the low temperature heat regenerator 4 is communicated with the heat absorption side inlet of the high temperature heat regenerator 3 after the outlet working medium of the compressor is converged, and the heat absorption side outlet of the high temperature heat regenerator 3 is communicated with the inlet of the heat source 1.

The middle lower part of the gas-liquid separation tower 9 is provided with a liquid outlet, and the upper part of the gas-liquid separation tower 9 is provided with an exhaust port.

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

The supercritical brayton cycle body comprises: the system comprises a heat source 1, a turbine 2, a high-temperature heat regenerator 3, a low-temperature heat regenerator 4, a recompressor 5, a precooler 6 and a main compressor 13; the intermediate stage split-flow throttling refrigeration system comprises: a bypass cooler 8, a cooling bypass mixer 12, a cooling bypass cooler 14, and a cooling bypass throttling pressure reducer 15; the impurity removal bypass includes: a bypass throttling pressure reducer 7, a bypass cooler 8, a gas-liquid separation tower 9, a booster pump 10 and a filtering bypass mixer 11. The refrigerating working medium of the intermediate-stage shunting throttling refrigerating system is the CO2 working medium in the system, and the compressor is the main compressor 13 of the supercritical Brayton cycle system, so that other refrigerants and compressors are not needed. The bypass cooler 8 is a shared device of the intermediate-stage flow-dividing throttling refrigeration system and the impurity removal bypass.