Performance and economic feasibility of a sludge/wastepaper gasifier system

Thermal gasification of densified sludge/wastepaper fuels has been shown to be technically feasible for the co-disposal of sludge and source-separated wastepaper. The performance and economic feasibility of a downdraft packed-bed gasifier system fueled with densified sludge/wastepaper and wastepaper fuels has been evaluated. To assess the performance of the gasifier, a series of gasifier runs was conducted at various air input rates with the use of various densified fuels. Char, a by-product of the gasification process, was evaluated as a substitute for powdered activated carbon. The performance of a small dual-fuel diesel engine combusting producer gas generated from the gasification of densified wastepaper was also demonstrated. The cost of sludge disposal in a sludge-wastepaper gasification system, using wood chips as an auxiliary fuel was found to be competitive with the cost of sludge disposal by landfilling if the electricity generated by the gasification system can be sold at a cost of $0.12/kWh, $0.09/kWh, and $0.85/k/Wh for communities sizes of 10,000, 30,000, and 50,000 persons respectively.