Co-combustion of Coal and Sewage Sludge in Coal-powder Boiler: Feasibility Assessment and Application

摘要

The co-combustion of sewage sludge (SS) and coal can widely used for the SS treatment. And yet, despite this treatment method possessing good investment and economic advantage, the feasibility of SS blended in coal-powder boiler have not been fully studied. By thermogravimetric analysis (TGA) study, the combustion characteristics of SS with coal-blended were investigated. The results show that SS is mainly burned in the low-temperature section, and the burnout characteristic of SS with coal-blended is influenced by volatile and calorific value. There is a best blended proportion for co-combustion. A CFD numerical study of co-firing coal and SS in a 300 MWe utility boiler was also presented. Mathematical results from the study show that the highest temperature of boiler reduced and radiation in boiler is affected as water content increased. And due to radiation in boiler reduced, the temperature of exit increased a little when the boiler blended sludge. On the basis of these studies, an industrial experiment is carried out in a Guangzhou power plant to identify the mixing program. The Industrial experiment results show that when coal is blended 5% and 10% SS, the flame is not changed obviously, burner and boiler exit has not coking, and the gas temperature of the entry of the high temperature super-heaters and the temperature of superheated steam increased but still in the allowed area. coal with 10% sludge is reasonable on the condition that the boiler is operated fully.