Combustion of Different Type Biopellets in a Fixed - Turbulent Fluidized Bed

摘要

According to our estimations, Russia can use up to 24 million tons of straw as fuel every year without harming either crop farming or agriculture. Straw as biofuel can be used for co-combustion with coal, including low-grade coal and coal waste (slurry). Taking into account the low bulk density of straw and granulometric composition of slurry (the particles are of size up to 0.2 mm) it makes sense to process this fuel into pellets, which are easy to transport and store. The feeding of pellets into a boiler furnace can be easily mechanized and automated. However, straw differs from wood and wood wastes by a high content of chlorine, silicon, phosphorus, and potassium. The presence of these compounds in straw contributes to the formation of slag agglomerates in the furnace, coherent deposits on the boiler heating surface and corrosion under these deposits. For the efficient combustion of biofuel with low-melting ash in boilers with furnaces with a small height the main combustion process should be carried out in the regime of a fixed, forced ventilated bed. Then, after a certain period of time, a bed must be transferred into a state of turbulent fluidization, and then returned to its original state. So the objective of the present work is to study the process of pellets combustion in such a bed (let's call it a pulsating bed).