INVESTIGATION OF THE MECHANISMS OF HEAT EXCHANGER CORROSION IN A MUNICIPAL WASTE INCINERATION PLANT BY ANALYSIS OF THE RAW GAS AND VARIATION OF OPERATING PARAMETERS

The detailed mechanism of high temperature chlorine corrosion, the dominant cause of corrosion in a municipal solid waste incinerator (MSI), has still to be clarified (Schroer, 2002). Upon its way through the boiler the raw gas is subject to various physical and chemical processes and interactions. Of these, sulphation of chlorides is supposed to have the major impact on chlorine corrosion (Neumann, 1997). The physical and chemical mechanisms of corrosion were investigated at a municipal solid waste incinerator. Both, the particulate and gas phase of the flue gas, were chemically and physically analyzed during their way through the boiler, at temperatures from close to 1000 °C down to 200 °C. The raw gas composition was analyzed during normal operation and soot blowing cleaning routine. Additionally, operating parameters of the plant were varied, and deposition processes were evaluated with the aim to find out primary measures to reduce corrosion rates. The particle mass concentration exhibits a bimodal size distribution with maxima at approximately 0.5 μm – growing by duration of travel – and 100 μm. First results show that sulphation of the particles can be observed upon travel through the boiler and on the fouling. Sulphur containing additives increased the sulphation of the particles during flight though not to completion