Waste incineration will produce a large amount of fly ash, that is, in the flue gas purification system (APC) and heat recovery system (such as heat economizer, boiler, etc.) collected and obtained the residue, accounting for about 20% of the total waste incineration ash.
It is an inevitable by-product of the domestic waste incineration process and is a hazardous waste, which may cause secondary pollution if not handled properly.
Fly ash collection, storage, transportation to strictly implement the relevant norms and standards to be in addition, should also be based on the subsequent use or disposal of fly ash pollution control requirements, choose the appropriate treatment technology. Fly ash collection and transportation pipelines, containers and pretreatment equipment should be kept closed to prevent the fly ash moisture absorption pipe plugging.
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Fly ash storage facilities should be equipped with anti-dust, rain, seepage (leakage) and other measures. In the fly ash storage, transportation process, should be used closed packaging or placed in sealed containers, or use closed tanker trucks bulk transportation. Fly ash should be done in and out of the plant, leaching toxicity testing and other management accounts of records, archives.
In recent years for the fly ash dioxin disposal technology shown in Figure 1, can be broadly divided into high temperature disposal technology, chemical disposal technology, low temperature pyrolysis technology and biodegradation technology, etc., the fly ash dioxin transfer to the gas phase after the main removal technology, including activated carbon adsorption technology and catalytic degradation technology, etc.. High-temperature disposal technology mainly includes cement kiln co-disposal technology, high-temperature melting technology and high-temperature sintering technology, etc.; chemical disposal technology mainly includes photocatalytic degradation, mechanochemical method, supercritical water oxidation, hydrothermal method and microwave oxidation method, etc.; low-temperature pyrolysis technology mainly includes direct thermal desorption and solid-phase catalytic pyrolysis; biodegradation technology mainly includes microbial degradation, etc.; catalytic degradation technology is mainly divided into catalytic oxidation technology and catalyst-coupled ozone technology. oxidation technology and catalyst-coupled ozone oxidation technology. Each technology has its own technical characteristics and scope of application, the following is mainly from the technical principle, research status and development trends and other aspects of a comprehensive description.
Cement kiln co-disposal technology process diagram shown in Figure 2, the fly ash into the cement kiln calcination disposal, in the burning section of the flame temperature in the high temperature zone of 1800 ~ 2200
℃, the material temperature in 1450
℃ or so, in the high temperature zone of the dioxin organic matter can be oxidized and decomposed completely into small molecules and other harmless substances. To meet the international "3T + 1E" principle, that is, the flue gas temperature control at 1100
℃ above, the flue gas residence time of more than 2 s, the flue gas perturbation is sufficient to ensure that the hazardous components of hazardous wastes are fully decomposed.
Cement kiln co-disposal technology process diagram shown in Figure 2, the fly ash into the cement kiln calcination disposal, in the firing section of the flame temperature in the high temperature zone of 1800 ~ 2200
℃, the material temperature in the 1450
℃ or so, in the high-temperature zone of the dioxin organic matter can be oxidized and decomposed completely into small molecules and other harmless substances. To meet the international "3T +1E" principle, that is, the flue gas temperature control at 1100
℃ above, the flue gas residence time of more than 2 s, the flue gas perturbation is sufficient to ensure that the hazardous components of hazardous wastes are fully decomposed.