Research On Waste Incineration Ash Deposition Characteristics In Fluidized Beds And Cold Simulated Experiment Of Ash Deposition

As the development of waste incineration in our country, the technology of fluidized bed waste incineration regarding to burn down the high moisture content, low heat value Chinese waste has burning stabilization and high efficient superiority. At present, it was applied allover China. However ash deposition and slagging of boiler back-end heat transfer surfaces in waste incineration process appears in some place. It's a new problem, as the technology of fluidized bed was applied. The ash deposition has affected the boiler heat transfer. Moreover gradual blowing-out ash was wanted. It has sharply cut down the owner's income. Therefore the request of the ash problem solution is extremely urgent.This article has analyzed the fly ash and deposited ash's chemical composition and the mineral composition, through the scene sampling. The deposited ash was inspected with the time change situation by laying aside ash stick in a industry waste incineration boiler's rear flue. The deposited ash which was obtained on the ash stick was analyzed regularly. Through microscopic appearance the inspection and the partial composition element analysis, the ash deposition mechanism of municipal solid waste could be revealed. Ca-based matter deposits on pipe surface and absorbs sulfur to form the sulfate unceasingly with HC1 presence. The ash deposition includes many kinds of fusible matter which can often form low melting point compounds. The moisture content is high in flue gas and the rear part flue reducible atmosphere are all factors of ash deposition.Medical wastes incineration releases more HC1, which causes serious metal device erosion and environment pollution. Absorption of HC1 by Ca-based sorbents in the incinerator is a cost-effective dechlorination method. The added sorbents result in the increase of fly ash and ash deposition on the heat-transfer surface. The fly ash and ash deposition from the incinerator were sampled, and the microstructure, elements and compositions were analyzed. Ca, Cl, Fe are found to be the main elements in the ash and deposits. CaO, CaCl₂ and the low-melting point compounds are the main compositions. The main cause of liquid sintering of the deposits is CaCl₂. Continued high-temperature sintering makes CaO crystal densification. The influences of the temperature, time and component to the sintering process were examined. To solve the ash deposition problem, some anti-sintering additives were studied. The experimental results show that ZnO and NaNO₃ can decrease sintering intensity, which are feasible additives.The simulating ash deposition experiment was carried out on the self-made small flue under the normal temperature condition. The ash was talcum powder carried by air.