tailieunhanh - An experimental study of oil recovery from sewage sludge by low-temperature pyrolysis in a fluidised-bed

Pyrolysis of activated sewage sludge was investigated under inert conditions in a fluidised-bed to study the effects of temperature and gas residence time on the product distribution and composition with an aim to maximise the oil yield. | Fuel 82 2003 465-472 An experimental study of oil recovery from sewage sludge by low-temperature pyrolysis in a fluidised-bedq Lilly Shen Dong-Ke Zhang School of Chemical Engineering Curtin University of Technology GPO Box U1987 Perth WA 6845 Australia Accepted 9 September 2002 available online 22 October 2002 Abstract Pyrolysis of activated sewage sludge was investigated under inert conditions in a fluidised-bed to study the effects of temperature and gas residence time on the product distribution and composition with an aim to maximise the oil yield. The temperature was varied from 300 to 600 C and the gas residence time from to s. Three groups of products were produced namely a non-condensable gas NCG phase a solid phase char and a liquid phase oil . A maximum of 30 oil yield wt daf of sludge fed was achieved at a pyrolysis temperature of 525 C and a gas residence time of s. Higher temperatures and longer gas residence times favoured the formation of NCG suggesting that secondary cracking reactions had occurred. The oil obtained was analysed using GC-MS and H NMR to determine the oil s composition and structure a unit structure of the oil was proposed which consisted of aromatic rings connected by hydrocarbons with -OH functional groups attached. 2002 Elsevier Science Ltd. All rights reserved. Keywords Fluidised-bed reactor Sewage sludge devolatilisation Oil structure 1. Introduction Sewage sludge like most organic wastes is abundant in volatile matter and thus there exists an opportunity to convert this stored energy into a usable energy source such as for heating or perhaps as a liquid fuel substitute and the production of speciality chemicals 1 . Presently most of the sewage sludge waste is disposed off in landfills ocean or via incineration 2 3 . The disposal of dewatered sewage sludge in sanitary landfills is not very satisfactory because of the inherent chemical energy lost and associated health problems 4 . Ocean dumping .