Practical experience has proven that rotary kiln or cement kiln incineration technology can handle industrial hazardous waste in solid, liquid, and gaseous states, making it one of the most widely used hazardous waste disposal technologies today. As of July 2019, there were 75 cement kiln co-processing projects (excluding Hong Kong, Macao, and Taiwan) in China that had obtained hazardous waste operation licenses, with an approved disposal capacity of 4.6252 million tons. Currently, cement kiln co-processing of hazardous waste mainly involves solid hazardous waste, liquid waste, and RDF (refuse-derived fuel) as alternative fuels, which are fed into the system through components such as the preheater, decomposition furnace, rear kiln inlet, and kiln hood. Compared with traditional landfill and incineration methods, cement kiln co-processing of waste offers significant advantages. However, due to its late start, the technology, operation, and supervision systems are not yet fully mature.
With increasingly strict control over cement production processes and product quality, many hazardous wastes are prohibited from being co-processed in cement kilns. Additionally, co-processing hazardous waste causes significant changes and fluctuations in operating conditions, flue gas composition, and material components, which exacerbates corrosion of the cement kiln cylinder and leads to ring formation or scaling within the system. This shortens the service life of refractory materials and seriously affects the long-term stable operation of the cement kiln.
As shown in Figure 2, the rotary kiln incinerator is a hazardous waste incineration device. Its main components include a rotary kiln, secondary combustion chamber, waste heat boiler, quench tower, acid removal system, and dust removal system. Various pre-treated hazardous wastes enter the combustion system through different feeding methods. Under the action of their own gravity and the continuous rotation of the rotary kiln, the materials are fully exposed to combustion-supporting air, completing the processes of drying, gasification, and combustion. Finally, the remaining residues are quenched into ash.
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