Design And Study On Heating Surface And Air Delivery System Of4t/h Biomass Briquette Mechanical Boiler

Currently, shortage of energy resource and ecological environmentdeterioration have become global crisis. Countries around the world have begun tofind cleaner energy instead of fossil energy. Biomass energy has been the worldwidefocus and hotspot because of its renewable performance, abundant resources andclean characteristics. In China, energy consumption is dominated by coal andindustrial boilers are the major factor in coal consumption. Coal combustion is themain reason of the formation of CO2, SOx, NOxand other pollutants. Therefore, theresearch and development of biomass fuels are comparatively mature. As the simplepreparation, high feasibility and wide range of application, combustion technique ofbiomass briquette flue has been a feasible way of efficient utilization of biomassresources, which is suitable for China.According to the current situation of China’s biomass briquette boiler which isnot yet mature, and the mechanization degree is not high, this paper puts forward tothe topic of design and study on heating surface and air delivery system of4t/hbiomass briquette boiler. Based on the consulting a large number of data and otherrelated manuals, this paper has been done complex structure calculations andthermodynamic calculation, and designed the heating surface and air delivery systemof4t/h biomass briquette boiler. The performance tests of heating surface and airdelivery system have been carried out under the rated condition. And the exergyeconomic of the heating surface has been analyzed in terms. Finally, the direct andindirect balance tests of4t/h biomass briquette boiler have carried on under the ratedcondition. Then the heating surface and air delivery have been evaluated by theoverall index, the main conclusions are as follows:（1）The radiant heating surface of4t/h biomass briquette boiler is disposed infurnace and reburning chamber. Convection heating surface includes convection bankand economizer. The area of radiant heating surface is17.21m~2and the convectionheating surface is145.6m~2;（2）After ventilation calculation, the total pressure drop of the flue is1253Pa,the total pressure drop of the air duct is1124.76Pa, and then the induced draft fan and the blower are selected. The model number of blower is G4-726C, the model numberof induced draft fan is Y6-417.1C;（3）The performance test results of heating surface and air delivery systemshow: the thermal efficiency of radiation heating surface, convection heating surfaceand economizer is97.7%,98.1%,98.6%, the exergy efficiency is55.43%,60.43%,69.51%. The efficiency of blower and induced draft fan is72.3%and61.1%. Actualoperation parameters of heating surface and air delivery system can reach the designrequirements value, and have good performance.（4）By the exergy economic analysis of heating surface, it is found that the costof unit heat transfer decreases first and then increased gradually with the increase ofvelocity of flue gas. When the velocity of flue gas is11m/s, the cost of unit heattransfer has a minimum value;（5）The thermal efficiency of the boiler is78.36%under the rated condition, inthis moment SO2, CO and soot content in the boiler exhaust conform to therequirements of environmental protection. It is illustrated that the heating surfaces andair delivery system can reach the requirements of the overall boiler operation, actualoperation level of the boiler can reach the design requirements.