Technical and environmental performance of 10 kW understocker boiler during combustion of biomass and conventional fuels

This paper treats about the impact fuels from biomass wastes and coal combustion on a small boiler operation and the emission of pollutants in this process. Tests were performed in laboratory conditions on a water boiler with retort furnace and the capacity of 10 kW. Fuels from sewage sludge and agriculture wastes (PBZ fuel) and a blend of coal with laying hens mature (CLHM) were taken into account. The results in emission changes of NOx, CO 2 , CO and SO 2 and operating parameters of the tested boiler during combustion were investigated. The obtained results were compared with corresponding results of flame coal (GFC). Combustion of the PBZ fuel turned out to be a stable process in the tested boiler but the thermal output has decreased in about 30% compared to coal combustion, while CO and NO x emission has increased. Similar effect was observed when 15% of the poultry litter was added to the coal. In this case thermal output has also decreased (in about 20%) and increase of CO and NOx emission was observed. As a conclusion, it can be stated that more effective control system with an adaptive air regulation and a modified heat exchanger could be useful in order to achieve the nominal power of the tested boiler.

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