Study On MSW Incineration Fly Ash Melting System Using Coal As Fuel

MSW (municipal solid waste) incineration technology has become the main MSW disposal technology in developed countries. It is also one of the most important directions for waste to energy conversion in China. Nowadays, more and more attentions have been paid on the secondary pollution caused by MSW incineration. Fly ash is the main carrier of heavy metals and dioxins pollutants. It is essential to put fly ash pretreatment into operation before landfill or reutilization. Melting and vitrifcation has been regarded as one of the best fly ash disposal technology. But up to now, even in developed countries, melting systems have not been large scaled applied due to its high energy consumption and flue gas treatment cost. Therefore, a novel fly ash melting system fired by coal combined with heat recovery process was proposed in this paper. Research on this system was developed as follows:1. TG and DSC instruments were used to analyze the melting characteristics of fly ash. The influences of different factors, such as atmosphere, heating rate, addition agent like CaO, SiO₂ and coal, on weight loss period, temperature range and latent heat were studied.2. Aspen Plus was chosen as the simulation tool of fly ash melting system. The influences of different factors, such as mass ratio, excess air ratio, primary air ratio and secondary air temperature, on system performance were analyzed. Calculation results and coal swirling flow combustion experience were combined to determine the feasible span of each factor. Analysis results can provide essential reference for subsequential systematic research and experimental study.3. The integrated model of fly ash melting combined with waste heat power generation system was developed based on Aspen Plus platform. Investment estimation and economic performance were studied. Results show that this system is feasible. Financial results, including investment, running cost, profits, etc. provide useful reference for demonstration plant. Technology features and economic performance of different kinds of melting system and gasification/melting technology have also been compared so as to determine roadmap of each technology.4. A test rig has been designed successfully, including feed system, reactors, separator, auxiliary sectors and measure/analysis facilities, etc. Besides, a detailed experiment procedure has been designed. These works ensure a promising start and solid foundation of succeeding experimental research.