Modeling as a Tool for the Optimal Design of a Downdraft Gasifier Operating on Waste Feedstock

Small-scale gasification coupled with an internal combustion engine for CHP generation is a well-explored method of bioenergy production. Several commercially available systems can be found across Europe. However, this kind of technology is typically designed to operate optimally and produce minimal tar only when clean, ideal feedstocks with a narrow distribution of moisture, size, and heating value are used. In Canada, the ability to utilize the abundant source of residual biomasses for CHP production would improve the economic case for these units significantly. Therefore, an adaptation of this kind of CHP system is required to be able to utilize alternative, low-value residual feedstocks and achieve optimal efficiency without excessive tar production. This study will investigate the utilization of a simplified kinetic/transport model for the design of a downdraft gasifier operating on residual feedstocks. Experimental data utilizing construction and demolition waste, oriented strand board and chipped pallets are used to validate the developed model. The results show that the model has the ability to be used as a predictive design tool for gasifiers to achieve optimal carbon conversion and reduced tar production for various feedstocks that are relevant to Canada.