Research objectives and content
Coal combustion for power production generates atmospheric pollutant emissions like sulphur dioxide, nitrogen oxides, and carbon dioxide. SO, emissions contribute to the acid rain effect which is still major environmental problem in the developed as well developing countries. Fluidized bed combustion (FBC) has been showed as a successfully alternative to conventional pulverised coal-fired boilers because of the higher combustion efficiency, lower SO2 and NOX emissions, better sorbent utilisation and reduced outlet particles concentration. FBC also presents higher availability than conventional pulverised coal- fired boilers to burn higher kinds of fuels (wood-chips, peat, urban and industrial wastes, etc.). The research project is directed towards understanding of the sulphur capture process in a FBC chamber. The first goal is to investigate the factors limiting efficient sulphur capture. In this sense the effect of residence time, sorbent reactivity, added particle size and size decrease of the sorbent used on sulphur capture performance will be study. It will be also investigated the emission of SO2 when different kinds of fuels are used (wood-chips, peat). Currently it is of great interest the reduction of N2O and NO emissions. The parameter changes introduced to reduce these emissions (i.e. reducing conditions) have a detrimental effect on sulphur capture. Thus, the second main goal of this project is to know the effect of reducing conditions on sulphur capture (i.e. study of SO2 capture versus operating conditions).
Training content (objective, benefit and expected impact)
This research project will improve the general understanding concerning the reduction of emissions and combustion processes in fluidized bed boilers. This will facilitate the design of large boilers, specially under conditions optimised for low N2O emissions rather than efficient sulphur capture. Important results obtained for methods to obtain low N2O emissions from the 12 MW boiler need to be extrapolated to units more than one order of magnitude larger. This project will give this needed understanding of the limitations for efficient sulphur capture. The training as such will also give important experience in planning, leading and evaluating large-scale research.
Links with industry, industrial relevance (22)
This project is closely related to the industry dedicated to produce and operate FBC combustors. The large 1'2 MWth CFB plant is serving as research plant in most of the above activities.