Integrated Optimization Of Flue Gas Desulphurization And Decarbonization Unit And Power Generation System In A Coal-fired Power Plant

To mitigate the adverse effects of the greenhouse effect and acid rain on the natural environment and global climate,it is necessary to control the gaseous pollutants such as SO₂ and CO₂ produced in thermal power plants,which could also realize energy saving and emission reduction.The most potential emission reduction technology is post-combustion capture technology,however,high energy consumption and investment costs affect its commercial applications.The sequential capture of SO₂/CO₂ process by calcium-based absorbent and the wet limestone desulfurization and ammonia decarburization process were modeled respectively in Aspen Plus software.The influence of the main parameters（gas-solid separation efficiency,purse rate,calcium carbon ratio,ammonia concentration and lean liquid load,et al）on the performance of the system was analyzed,the optimal operating parameters was selected.Two schemes were proposed respectively to integrate the capture system with the thermodynamic system,and the best schemes of the two processes were selected,and the thermal performance,power generation cost and carbon capture cost of the two schemes were compared.Compared with the optimal integration scheme of the two processes,the net output power of Calcium method is 37.768 MW higher than Ammonia method,however,the former need additional coal to provide heat for calcination,therefore increasing of 3.28g/（kW?h）in coal consumption rate than the latter,and 0.3%reduction in thermal efficiency than latter.The latter process increases the complexity and heat loss of the integrated system because of the addition of ammonia capture device and cooling equipment and the need of extracting different steam from the unit to provide heat to its reboiler.Therefore,the cost of the system investment,equal annual amortization cost,and operation and maintenance costs are higher than calcium method,the power generation cost and carbon capture cost are 0.023 ￥ /（kW?h）and 35 ￥ /tCO₂ higher than calcium method.Considering all factors,calcium-based absorbent sequential capture process has obvious advantages.