Time Dependent Behaviour of Deposits - Assessment of the Influence on Heat Transfer, Pressure Loss and Corrosion in MSWI-Boilers

Project Number 228

In power plants, fouling causes cost-intensive reduction of track time and availability. This limitation is due to hinderance of heat transfer, increase of pressure loss and stronger corrosion.

In this context, layer depth and surface form of these deposits play a significant role, which can clearly be seen in the physical equations for the mentioned phenomena. In addition, the thermal conductivity is a significant value for the heat transfer and the diffusion, esp. porosity, for the corrosion. Aim of the project is to determine the values deposit geometry, thermal conductivity and porosity with particular emphasis on the characterization of the geometry of the deposits.

The investigations are carried out using optical analysis of the deposit geometry over the time. A high-temperature-(HT)-endoscope (operating range up to 1200 °C; requires a 2'' flange only) will be inserted into boilers of different municipal solid waste incineration plants (MSWI). The variation of the deposits can be documented on video film. The influence on the deposits caused by boiler cleaning systems, i.e. soot blower, bumpers and water blowers, will be documented in particular. Furthermore, on-line sampling of deposits through a modified manhole offers the possibility to investigate chemical-mineralogical changes.

In addition to gaining knowledge concerning the geometry of deposits, measured thermal conductivity and porosity, the effectiveness of boiler cleaning equipment shall be evaluated and optimized.

The project is carried out from July 2002 to December 2004 by Clausthaler Umwelttechnik-Institut GmbH, Clausthal-Zellerfeld (person in charge: Dr. Ragnar Warnecke). The project is accompanied by a working group of the Working Panel "Thermal Waste Utilisation".