Abstract
An urgent problem in Ukraine is overcrowded sludge sites with outdated sludge deposits. Due to the food problem, the world needs to maximize the release of land areas that have been under technical use and reclaim them for agricultural land. Therefore, the processing of obsolete sludge deposits makes it possible to reuse land for activated sludge or for reclamation for other needs of the country. The paper sets the task of studying obsolete sludge deposits to create a technology for their processing. Due to the high ash content of old silt deposits, it was proposed to combine them with peat and biomass. This will reduce ash content by 1.5–2.0 times. Since the created composite granules and the sludge deposits themselves have a high moisture of 61–68 %, the drying kinetics was studied on a convective experimental stand to reduce it. The research results showed that composite granules have a drying time of 28–39 minutes to a moisture content of 6–7 %, which is 2.3–3.1 times faster than peat. The equilibrium moisture content of composite granules was determined to be 6–7 % and not exceeding the standard moisture content for fuel granules. The heat of combustion of obsolete sludge deposits, which is 11.8 MJ/kg, and the resulting composite granules based on them, was determined, which is quite high and, depending on the composition, is in the range of 13.4–15.5 MJ/kg. During the study of the combustion of a separate fraction of aged sludge deposits, it was found that the combustion process occurs in the upward convective flow of the oxidant behind the double boundary layer. It was determined that the combustion rate is independent of its size and is the same, but the mass affects the time of ignition. Further studies on the combustion of composite granules showed that the combustion rate of the granules is significantly lower than the combustion rate of the original biomass, but the combustion rate of a separate fraction of silt deposits prevails. Bibl. 32, Fig. 8, Tab. 1.
Publisher
The Gas Institute of the National Academy of Sciences of Ukraine
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