摘要
With around 10 tonnes of waste being generated for every maul woman and child each year across the globe, safe disposal of it all has become an urgent environmental problem. In 1993, Western Europe,the United States, Canada, Japan, Australia and New Zealand produced a total of 480 millon tonnes of industrial waste and & billion tonnes from activities such as energy production, agriculture, mining and sewage disposal. The emission to the atmosphere of both heavy metals and acid gases and perhaps more important in the longer term, the Dioxins/Furans (PCDDs/PCDFs), promises to be one of the key issues facing not only the industry but the society as a whole over the next decade and more.Although it is increasingly likely that measures to control toxic emissions will have to be directed at a wider target than just the waste incinerators, it is equally certain that both public opinion and legislation will, at least in the first instance, see the incinerators as one of the most obvious candidates for tighter regulation.These days, virtually all the new research and development techniques in combustion technology involve the application of computational fluid dynamics (CFD) to combustor design. This seems to be the best approach to solving design problems. Mathematical modelling thus is seen as an inherent part of.practically all combustion research programmes. The new discipline of computational fluid dynamics can also be used to help minimize flame generated pollutants released to the atmosphere. These pollutants include; CO2, CO, SO2, NOx, HC1, Hydrocarbons, soot, particulates, heavy metals and dioxins/furans. CFD studies of their release to the atmosphere must include not only their source in the flame, but also their removal from the fine gases by scrubbing and other techniques. The governing differential equations for the process being studied must be defined and solved simultaneously if the parameters in the equations are interacting. At present, this procedure can give valuable insight into the effect of design parameters on the flow field and concentrations of major species. In the case of many pollutants, the equations governing their production does not affect the flow field or concentrations of major species. Thus the equations are effectively decoupled and the pollutant formation, convection and diffusion can be calculated in a post-processor.This paper presents and discusses the results of our CFD modelling work at two large municinal and a newly commissioned 5 MW clinical incinerator plants in UK.
