Thermodynamic Performance Analysis Of The Coal-fired Power Plant With CO₂ Capture

Significant amounts of CO2 coming from fossil fuel combustion has led to climate change, thereby seriously endangering the ecological balance. Under the global implementation of energy conservation, China is now bearing tremendous pressure due to the large amount of CO2 emissions.Since CO2 emissions are mainly from coal-fired power plant flue gas, capturing CO2 from the flue gas is one of the best solutions to mitigate CO2 emissions. The main methods for CO2 capturing includes physical absorption method, chemical absorption method, physical and chemical absorption method, adsorption method, separation membrane and et al. The CO2 capturing system based on monoethanolamine(MEA), which belongs to post-combustion chemical absorption method, is now recognized as the most mature carbon capture technology. In this paper, the research mainly aims at the coupling characteristics between CCS based on MEA and coal-fired units. The main contents are as follows.Firstly, the CO2 absorption mechanism of MEA liquor is presented. It analyzes the energy consumption characteristics of carbon capture systems based on MEA. Besides, by establishing the calculation model for regenerative energy consumption, this paper analyzes the effect of variation of key system parameter including the carbon capture rate, density of absorption and CO2 load of absorption. Equivalent Enthalpy Drop and Heat Balance are applied for system energy analysis and the heat-economical index for coal-fired units coupled with carbon capture system based on MEA are proposed.Next, taking some domestic supercritical 600 MW coal-fired unit as the research object, the energy flux and mass flux are analyzed, the coupling methods for coal-fired unit and carbon capture system are proposed, as well as their characteristics. In addition, the effect of variation of system parameters, such as MEA density of absorption and carbon capture rate, on the heat-economical index for every kind of coupling method is also assessed.Lastly, the technological economy analysis for every coupled system is conducted to reasonably assess the economic feasibility for future development of coal-fired units coupled with carbon capture systems. This paper establishes the power generation cost model and CO2 emission reduction cost model of coupled systems, using which it evaluates both the cost of power generation and CO2 abatement. It shows that the decrease of carbon tax and the increase of carbon price can compensate the increased power generation cost causing by the carbon capture systems. So the carbon capture power plants are expected to exceed economic barriers and achieve large-scale reductions of CO2 emissions under the assurance for economy of traditional systems.