A coal gasification supercritical CO2 cycle power generation system

Abstract

A gasification supercritical CO2 cycle power generation system comprises a gasification unit, an air distribution unit and an internal combustion type supercritical CO2 circulation unit, wherein air is input into the air distribution unit, oxygen is generated and output in two paths, one path of oxygen is input into a gasification furnace, and the other path of oxygen is input into a combustion chamber of the internal combustion type supercritical CO2 circulation unit .The internal combustion type supercritical CO2 circulation unit further comprises a turbine for converting heat energy into mechanical energy and a heat regeneration unit used for heat exchanging, and a part of gas is extracted from the portion between turbine stages, or a turbine outlet or a cold side hot end outlet of the heat regeneration unit to serve as a gasification agent to be input into the gasification furnace in the gasification unit .While zero CO2 emission of the gasification supercritical CO2 cycle power generation system is achieved, high system efficiency is obtained, and the net efficiency is higher than that of an integrated gasification combined cycle power generation system based on pre-combustion trapping by 8-14%.

Description

technical field [0001] The invention belongs to the field of energy power and coal chemical industry, in particular to a coal gasification supercritical CO 2 cycle power generation system. Background technique [0002] Under my country's coal-based energy structure, how to reduce CO2 in coal-based power stations efficiently and at low cost 2 Emissions are an important issue facing the energy sector. Conventional coal-based power station CO 2 The technical routes for emission reduction include pre-combustion capture, post-combustion capture, and oxygen-enriched combustion. [0003] Post-combustion capture refers to the separation and capture of CO from flue gas after combustion 2 , the main application object is the conventional pulverized coal power station. Its main advantages are mature technology, simple principle and good inheritance to existing power stations. The disadvantage is that due to the large volume flow of flue gas after combustion, CO 2 The partial pre...

AI Technical Summary

Problems solved by technology

However, due to the supercritical CO 2 The physical properties of the working fluid, the above two types of cycles face two problems: 1) CO under high pressure 2 As the temperature decreases, the specific heat will first increase and then decrease, which is prone to the problem of heat transfer mismatch in the low temperature section, which will bring about a large loss; 2) Under the operating parameters of the turbine, CO 2 The specific heat ratio is lower than that of air or water vapor. At the same drop pressure ratio, the temperature ratio of the inlet and outlet of the turbine is small, and the exhaust gas temperature of the turbine is high. Due to the limitation of the material of the regenerator, the inlet temperature of the turbine cannot be increased, and it is difficult to improve the efficiency.

Due to the steam cycle and CO 2 Due to the difference in circulating working medium, it is impossible to share the equipment, so it is necessary to set up two independent power generation systems, resulting in complex systems, high investment costs, and difficult control, and due to the small steam flow rate, the steam turbine is small in scale, and its internal efficiency is relatively large. The turbine is about 6-8% lower and the efficiency is further reduced

[0009] To sum up, currently used in coal-based power station CO 2 The three technical routes for emission reduction have the problems of low system efficiency and high power generation cost. It is urgent to develop near-zero emission coal-based power station technology through circular innovation.

Internal combustion supercritical CO 2 cycle proposed, for coal-fueled CO 2 Zero-emission systems offer new options, but internal combustion supercritical CO 2 There are still some technical problems in the cycle, and when it is combined with coal gasification, if only the sharing of air separation and the combination of fuel are considered, the system will be complicated and the system efficiency will be low

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