Guangdong Typical Biomass Combustion And Flue Gas Emission Characteristics

With the increase in China’s economic development and urban population, environmentalpollution and energy shortages are becoming increasingly prominent. The development ofsustainable use of renewable energy to replace dwindling fossil fuels is an urgent need.Biomass has been widely appreciated due to its low emissions and inexhaustible naturalcharacteristics. From the current point of view, biomass direct combustion technology is themost widely used biomass energy utilization technologies. The fuel properties is the mainreason which caused the precipitator wear and out of order of the power plant feedingsystem,so the study of the combustion characteristics of biomass fuels is very necessary.Combustion characteristics and emission characteristics of several Guangdong Provincetypical biomass fuel: eucalyptus bark, crushed eucalyptus, sugar cane bagasse and sugar caneleaves were studied using thermal gravimetric analysis, the tube furnace and flue gasanalyzers. And the combustion kinetics parameters were calculated.Through a series of TGA experiments, we investigated the influence of heating rate andcombustion atmosphere on the combustion characteristics of four biomass fuels. The resultsshowed that: with the heating rate increasing, the burning mass loss rate of biomass fuels inthe whole course have increased, and the largest increase is in the DTG curve peaks.In thesame atmosphere, the heating rate is faster, the peak temperature is higher, and thecorresponding conversion rate is larger, and will produce a thermal hysteresis. The influenceof oxygen concentration on biomass burning is segmented. The impact of oxygenconcentration on volatiles separating out and burning is small; the impact on the fixed carbonburning is large. By the dynamics calculations, bark, wood and bagasse in the low heatingrate conditions, the activation energy of fixed carbon combustion stage increased with theincreasing of oxygen concentration. Analysis of the process under high heating rate, bark,wood and bagasse volatile, with the increasing of oxygen concentration, the activationenergy increased. In the same oxygen concentration, bagasse volatile precipitation activationenergy of the combustion phase increases with the increase of the heating rate. Bagasse andcane leaves fixed carbon combustion difficulty extraordinary increased in the oxygen-poorconditions.Experimental study on the combustion process of biomass fuels through the tube furnaceexperiments, the study found that different biomass fuel combustion characteristics arebroadly similar, but there is some difference. From the weight loss curve point of view, thefurnace temperature of500°C and600°C, the bark sample combustion is slow. When thefurnace temperature reaches700°C,the combustion is entering the rapid combustion state.While the wood bits and sugar cane leaves entered a state of rapid burning when the oventemperature is600°C. Bagasse got rapid combustion at low temperature (500°C). Fromindustrial combustion residue analysis results, in a slow-burning state, the precipitation ofmoisture is before the volatile precipitation, the two phases went separately. A very smallamount of the combustion of fixed carbon in the volatile matter in the precipitation stage.Inthe fast burning state, the temperature is not the main factor to affect the combustion process.The burning rate is determined mainly by the diffusion of oxygen,and the water precipitationstage is very short, which is difficult to judge from the weight loss curve.In high temperature combustion, NOx emission is accompanied in the entire combustionprocess. At low temperature (500°C) combustion, NOx emissions are very small. As thefurnace temperature increased, bark, wood and sugar cane leaves NOx emissions curve peakis significantly increased, and the higher the furnace temperature, the peak the soonerappeared. Four biomass fuel combustion emissions of NOx at the furnace temperature of600°C, NO and NO2were similar. As the temperature rises, the NOx composition changed dramatically, showing a sharp increase of NO content, and NO2decreases sharply. Over thetime, the NO component content is an increasing trend, while the NO2component tends todecrease in the proportion. The simulation results of Chemkin is as the same as theexperiment results.