Design And Research On Furnace Of Biomass Chain-steam Boiler

China is facing a dual crisis of energy and environment is increasing.In this context,the development and utilization of biomass has a great significance for energy conservation,improving air quality,improving resource utilization and ease the energy crisis.After the straw,sawdust and other agricultural waste molding,replacing coal fuel for small and medium-sized industrial boilers,which is one of the important way for biomass resource utilization at the present stage in China.At present,most of the biomass boiler are based on the original coal-fired boiler,directly to the gasification of biomass fuel.Its furnace structure without reasonable design,leading to the furnace fouling and slagging serious problems,low thermal efficiency.Aiming at the defects of traditional biomass boiler furnace,combining biomass combustion theory research,a kind of new furnace structure was put forward.The furnace structure was applied to a steam boiler which rated evaporation was 1t/h and rated steam pressure was 0.7Mpa,introducing its design and experimentation.The main conclusions are as follows:1)Its technological innovation mainly embodied in the furnace arch structure,secondary air system and the design of dust collecting device.The furnace is divided into three combustion chambers by using the multi arch structure;Secondary air in the fuel layer is formed above the approximate circular flow disturbance,improving the degree of burnout;Arrangement sonic soot blowing,reducing fouling and heating on surface and smoke pipe.2)The new furnace design applications on the 1t/h chain-steam boiler,after design and calculation,the furnace volume is 4.5m³,the perimeter area is 10.06m²,total effective radiation heating area is 7.48 m²,the furnace emissivity is 0.50,the flame emissivity is 0.275.3)Using maize straw,bagasse,weedtree powder three kinds of biomass briquette,carrying out thermal performance parameter test,condition for 100% rated load.The combustion efficiency is 97.57%,96.67% and 97.91% respectively;The furnace outlet temperature of the furnace is 817,799 and 835℃;Pollutants generated,slagging tendencies and thermal performance is superior to existing conventional biomass boiler.4)In eight test conditions,the optimum working conditions in the new furnace when αpy = 1.50.At this time,the combustion efficiency is 97.04%,the flue-gas temperature is 799℃,the Oxygen Concentration at furnace Outlet is 5.2%.5)The temperature distribution along the height direction,the first and second combustion chamber showed the trend of first increases and then decreases,reaches the maximum value at 0.4m height;The first combustion chamber rebound within the range of 0.6 0.8m height;The furnace temperature distribution along the transverse cross-sectional direction,the first combustion chamber at 0.4m,1.2m and 1.6m height distribution.6)The gas concentration distribution along the height direction,O₂ concentration decreased first and then increased,reached the lowest level at 0.4m height,stable at around 9.00% after 1.2m height;CO₂ concentration increased first and then decreased,reached the highest level at 0.4m height,stable at around 8.20% after 1.2m height;CO concentration increased first and then decreased,finally tends to a constant;CO concentration decreased within 0.4m to 0.8m height because of the conversion to CO₂;Gas concentration distribution along depth direction in the furnace,low concentration at the wall;In the furnace central region,CO₂ and CO concentration is high,O₂ concentration is low.