Quality-divided and graded utilization method and system of coal-burning supercritical carbon dioxide power generation flue gas energy and working medium energy

Abstract

The invention relates to a quality-divided and graded utilization method and system of coal-burning supercritical carbon dioxide power generation flue gas energy and working medium energy. The quality-divided and graded utilization method and system of coal-burning supercritical carbon dioxide power generation flue gas energy and working medium energy have the benefits as follows: firstly, high-grade flue gas energy and working medium energy multistage reheat expansion measures are utilized, so that a isothermal heat absorbing process being close to the temperature of a high temperature heat source is realized, the average heat absorbing temperature is improved, and the circulating efficiency of the system is improved; secondly, middle-grade flue gas energy and working medium energy coupling, graded dividing and backheating measures are utilized, the energies of the flue gas and working medium in a medium temperature zone are fully utilized in a graded manner, the heat transfer temperature difference of cold and heat fluids are reduced as far as possible, the irreversible loss of available energy due to large temperature difference is reduced, and both the heat exchange efficiency and circulating efficiency are improved; thirdly, a low-grade flue gas energy and working medium energy graded heating cold air and fuel system is utilized, the low temperature exhaust heat of flue gas and working medium is utilized, the heat of flue gas and working medium released to the environment is reduced, a isothermal heat releasing process being close to the environment temperature is realized, the cold end loss is reduced, and the circulating efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of new fossil fuel power cycles, and specifically relates to a method and system for utilizing coal-fired supercritical carbon dioxide power generation flue gas energy and working medium energy by quality and classification. Background technique [0002] The supercritical carbon dioxide cycle power generation system, because the cycle layout is closer to the theoretically optimal generalized Carnot cycle, can achieve higher cycle power generation efficiency at a lower endothermic temperature, avoiding the use of expensive high-temperature nickel-based alloys, and The size of the equipment is far smaller than the steam unit with the same parameters, and the technical and economical efficiency is very good. [0003] However, the supercritical carbon dioxide cycle power generation system using coal as a heat source has its unique characteristics, and there are still some problems to be solved. The first is the...

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Problems solved by technology

The first is the reasonable cascade utilization of coal-fired flue gas. Due to the large amount of reheating in the circulation system, the boiler inlet temperature has reached above 500°C, so the flue gas temperature in the tail flue of the boiler is very high, generally above 600°C. The outlet hot air temperature of the conventional air preheater is generally about 400°C, which makes the waste heat of the flue gas at 600°C-400°C unusable, and the thermal efficiency of the boiler is low, which seriously affects the power generation efficiency of the unit.

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