Fixed bed downdraft gasification of paper industry wastes

The two main wastes generated from secondary fibre paper mills are rejects (composed mainly of plastics and fibres) and de-inking sludge, both of which are evolved from the pulping process during paper manufacture. The current practice for the disposal of these wastes is either by land-spreading or land-filling. This work explores the gasification of blends of pre-conditioned rejects and de-inking sludge pellets with mixed wood chips in an Imbert type fixed bed downdraft gasifier with a maximum feeding capacity of 10 kg/h. The producer gases evolved would generate combined heat and power (CHP) in an internal combustion engine. The results show that as much as 80 wt.% of a brown paper mill's rejects (consisting of 20 wt.% mixed plastics and 80 wt.% paper fibres) could be successfully gasified in a blend with 20 wt.% mixed wood chips. The producer gas composition was 16.24% H-2, 23.34% CO, 12.71% CO2 5.21% CH4 and 42.49% N-2 (v/v%) with a higher heating value of 7.3 MJ/Nm(3). After the removal of tar and water condensate the producer gas was of sufficient calorific value and flow rate to power a 10 kWe gas engine. Some blends using rejects from other mill types were not successful, and the limiting factor was usually the agglomeration of plastics present within the fuel. (c) 2012 Elsevier Ltd. All rights reserved.