Application Study Of Comprehensive Evaluation Of Coal-fired Bolier’s Economy And Environment With Exergy Theory

The low resource utilization efficiency and serious environmental pollutionare always very important and practical problem of the coal fired utility boiler.The scientific and comprehensive analytic method for the evaluation of boileris needed to dig the energy saving and emission reduction potential. As theeffective thermodynamics analytic theory, the exergy method is one of theimportant methods of the coal-fired boiler’s cleaner production for analyzingand evaluating the boiler’s operation and removal of pollutants.This paper analyzes the economic and environmental protectioncharacteristics of sub-critical600MW coal-fired boiler based on the exergytheory. In combination with the thermodynamic exergy analysis and thespecific consumption theory, the exergy models of the boiler’s heat exchangersare established and perfected. Based on the operation data, the energyconsumption distribution of typical coal-fired boiler is analyzed from the angleof temporal and spatial distribution, and the curve graph of the variable loadoperating boiler economic characteristic is drew. The exergy models of theenvironmental protection characteristic of boiler are established, the emissionexergy are analyzed, for instance, SO₂, CO, NOx, CO₂, and the curve graph ofthe variable load operating boiler economic characteristic is drew. Theenvironmental impact of the emissions is evaluated, and the exergy theory isapplied to constitute the emission standard of air pollutants for coal-fired boiler.When the coal-fired utility boiler is producing electric power, it not onlyconsumes the resource, but also emits the pollutants. The comprehensiveperformance will be affected by the operational condition of environmentalprotection equipments, so the evaluation of boiler needs the comprehensiveevaluation of their operation process both economic and environmental performance. This paper applies the exergy theory to establish thecomprehensive evaluation index system of coal-fired utility boiler, andevaluates the boiler’s comprehensive performances under the variable loadoperation with the combination method of AHP and the Gray Relational Degree，and reveals the main influence factors and make the operation suggestionsunder the high load operation..The research results in this paper evaluate the boiler performanceobjectively based on the second law of thermodynamics, and it is different fromthe direction of heat method for boiler’s optimization operation the heatexchange and auxiliary equipments reform to save energy and reduce emission,moreover, the theoretical support is provided to further study improving theboiler’s comprehensive performance under the high load operation.