Combustion, biomass operating characteristics

It should be noted that the combustion tests were conducted with only primary air supply. Attempts were made to keep the feed rate and excess air as similar as possible between trial burns, however, the operation conditions were very hard to keep fixed, as the excess air was controlled manually and these biomass fuels do not have good flow characteristics due to their inconstant particle shape, uneven particle size distribution and high moisture content. Many studies related to incomplete combustion have focused on processes with two-stage air supply and have identified that excess air is a key factor influencing the formation of CO and CH (2, 4, 5. 13). It has also been shown that each wood furnace has a typical correlation between the CO-emissions and the excess air ratio regardless of fuel type (13). 

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