silt disposal has been a haunting challenge for urban solid waste treatment. the chn energy (changzhou) longyuan thermal power and silt recycling collaborative utilization project is the first large generation unit-based silt disposal demonstration project in china. at the project site, silt is diverted into an underground pit, and then sent to the inlet of the steam disc dryer, where it becomes dry sludge with a water content of 30%-40%, water vapor and exhaust gas.
the dry sludge is then thoroughly mixed with the raw coal in precise proportions via a coal conveyor belt and sent to a boiler for incineration. during this process, the odor emitted by the silt will be absorbed by the negative pressure pumping device and returned to the power station boiler for incineration. the flue gas produced in the process of combustion is treated by the power plant’s original environmental protection facilities to remove dust, sulfur, nitrogen and other pollutants to achieve ultra-low emissions, the ash produced is ground and turned into concrete materials for use in construction projects.
since it was put into operation in 2020, the project has undertaken about one-third of changzhou’s general solid waste harmless disposal task, and has treated 214,000 tons of silt, recuing the city from the “siege of sludge”. it is estimated that the project can save 17,100 tons of standard coal, reduce carbon dioxide emissions by 45,300 tons, and provide more than 6,300 tons of ash as construction concrete materials per year.
it is reported that longyuan environmental protection co., ltd. under chn energy is constructing more than 20 silt disposal projects, covering the middle and lower reaches of the yangtze river and the beijing-tianjin-hebei region. according to li xiaojin from the company, by 2025, the total number of projects put into operation will exceed 30, forming an annual silt treatment industry capacity of 3 million tons.