Experimental Study On Cyclone Combustion Characteristics Of Sawdust

The coal based energy structure in China will not only lead to the depletion of coal,but also bring about serious environmental pollution. Taking the national condition thatChina serves as an agricultural country into consideration, the expoitation and utilizationof biomass, typically agricultural wastes, comes into notice over the years. Among all theutilization technologies, thermochemical conversion represented by direct combustion hasan enormous potential market. Biomass direct combustion technology, as one of the oldestways of utilization, gains favor because of its simpleness and maturity. The traditionalcombustion technology of biomass, in general, is inefficient due to the low burningtemperature, thus limiting its widespread. The combustion of biomass micron fuelovercomes these shortcomings thanks to the smaller particle size which could promote thediffusion of oxygen.This paper mainly studies the influence of air flow rate, feed rate and particle size onthe temperature, the flue gas and the residual during biomass micron fuel combustion.Meanwhile Fluent is used in order to simulate the combustion of the furnace employed inthis experiment. In addition, the comparison between the practical experiments andsimulation is made to see whether the results obtained through simulation are reliable ornot.The result shows that the temperature of the furnace will increase first and thendecrease with the increase of air flow rate on the condition that the particle size and feedrate are both kept as constant. While the concentration of carbon monoxide will decreasewith the increase of air flow rate. Considering both temperature and concentration of CO,the best condition occurs with the excess air coefficient of1.08-1.16.When the particle size and the air flow rate are kept unchanged, the temperature offurnace will increase first and then decrease with the increase of feed rate. While theconcentration of CO will consistently increase. If taking both temperature andconcentration of CO into consideration, the best condition will be obtained when thepowder-air proportion is between210g/m3and260g/m3.Select five points in order to study the influence of particle size on the combustioncondition. The result shows that the smaller the particle size is, the higher the temperature will be and the lower the concentration of CO will be.The carbon conversion rate of residuals with different particle sizes is measured andthe result shows that the smaller the particle size is, the higher the carbon conversion ratewill be. The highest carbon coversion rate is as high as90%with the particle size smallerthan125μm.When using different indicators to evaluate the slagging levels of the residuals, itcould be found that it will lead to serious slagging problems according to the silicon ratioand slagging discriminant index. While if it is measured through the silica-alμmina ratioand the iron-calciμm ratio, it is slight slagging for the residuals.If comparing the experimental results and the simulation results, it can be seen thatdeviation is between±10%, and in most cases between±5%, which means that thesimulation results are acceptable. Therefore, simulation could reflect the actural conditionto some degree.