Comparison of air gasification of solid organic waste and pellets with the addition of low-grade coal

The growing volume of organic and wood waste requires effective processing methods to recover secondary energy resources. Thermal gasification of biomass and combined fuels using air as an oxidant is a promising approach to generate gas for heat, electricity, and chemical production. However, an increase in nitrogen content reduces its calorific value, making it important to use combined pellets with added coal to enhance energy efficiency and process stability. The purpose of this study is to investigate the gasification processes of biomass pellets blended with low-grade coal, to determine the effect of the air excess ratio on the composition and calorific value of the generator gas, and to evaluate the efficiency of combined pellets to recover secondary energy resources. A mixture of sunflower meal and wooden packaging waste with the addition of Donetsk ASh-grade coal has been used as the research material. The pellets have been formed using a mechanical pellet press at a pressure of 5–8 tons, a diameter of pellet is 25 mm, and a length of pellet is 15–30 mm. Pellet gasification has been carried out on an experimental installation with air supply at excess factors  = 0,2–0,4. The composition of gases has been determined by gas chromatograph. An experiment has been conducted on the thermal processing of pellets from solid organic agricultural waste in a reverse-flow gasifier. Based on the results of the experiment, the effect of adding coal to the solid organic agricultural waste has been assessed. The resulting generator gas with a calorific value suitable for combustion in power boilers has been obtained. It has been found that increasing the air supply enhances the yield of gaseous products due to the deep oxidative processing of raw materials. At  = 0,2 combustible components (CO, H₂, CH₄) predominate, while at  = 0,4, the proportion of inert gases increases and the heat of combustion decreases. The optimal range of  = 0,2–0,3 ensures maximum yield of combustible generator gas during controlled oxidation. Biomass pellet gasification with coal addition enables the efficient production of generator gas with a high calorific value that is twice as high as that of pure biomass, making it a promising technology for the processing of organic waste and the production of secondary energy resources.