Optimization Of Operational Parameters And Economic Study On Cofiring Bituminous Coal With Lignite In Circulating Fluidized Bed Boiler

To figure out the combustion characteristic of blended lignite in the CFB,analyze the effect of blended coals quality on boiler operation, find the best parameter for operation,improve the boiler's efficiency by lowering exhaust gas loss and unburned carbon loss,reduce auxiliary power consumption,alleviate the wear of the heating surface in the furnace and make sure that the boiler operates safely, stably and economically, After retrofitting,the field tests were conducted on coal blends and economy of cold state and hot state in a coal-fired circulating fluidized bed boiler with a steam capacity of 480t/h,On the basis of the results of hot-state tests.In the cold-state test,the main parameters of the primary and secondary air were ascertained.Systematic researches for combustion optimization were conducted on the Primary &secondary air distribution, excess air coefficient, bed pressure and bed temperature in the hot-state test.The calculating results indicated that ash content,moisture content and net calorific value as received basis vary linearly while cofiring bituminous coal with lignite.If blending ratio of lignite exceeds 60%,the temperature of exhaust gas will rise about 7.4-8.2 degrees centigrade, the amount of flue gas will increase by 36.33Nm3/s, and the boiler efficiency will decline 1.018%.By Optimizing the operational parameters, the average values of boiler efficiency increased from87.671% to 90.845%,in the meanwhile the comprehensive auxiliary Power consumption rate for a power plant decreased from 12.306% to 11.233%.