Public announcement regarding the acceptance of the project for the coordinated treatment of biochemical sludge at Inner Mongolia Yitai Gasification Facility

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Public announcement regarding the acceptance of the project for the coordinated treatment of biochemical sludge at Inner Mongolia Yitai Gasification Plant. Author/Source: Coal Chemical Industry 114 Forum. Date: June 15, 2021. Clicks: 15. The Ordos Ecology and Environment Bureau issued a public announcement in May 2021 regarding the acceptance of this project. The 1.2 million tons per year fine chemicals demonstration project of Inner Mongolia Yitai Chemical Co., Ltd. is equipped with 6 HT-L pressurized coal gasification units and 3 multi-feed slurry gasification units (2 in operation and 1 as backup). According to the public information, biochemical sludge is treated by directly adding raw coal. Both the space furnace and the multi-material slurry gasifier are used together to treat biochemical sludge. The biochemical sludge amounts to 6,720 tons per year. Of this, the pulverized coal gasification unit uses 4,880 tons of biochemical sludge per year for co-firing, while the water-coal slurry gasification unit uses 1,840 tons per year (the proportion of biochemical sludge used in the pulverized coal gasification unit is 0.15% of the raw coal, and that in the water-coal slurry gasification unit is 0.26% of the raw coal). Upon completion of this project, the main structure of the existing facility, its production capacity, process flow, product composition, and output levels will remain unchanged. The capacity, process flow, and equipment of the existing pulverized coal gasification units and water-coal slurry gasification units remain unchanged, with no impact on downstream product plans or emissions and waste discharge. Solid waste is ground together with raw coal and an aqueous solution of additives in a certain proportion to produce a slurry with a low calorific value of ≥11,000 kJ/kg; this slurry is then injected into the gasification furnace from the top ； Waste liquid with a high calorific value is injected into the gasification furnace through a dedicated channel for waste liquid. Inside the gasifier, the organic matter in solid waste is completely decomposed into crude syngas primarily composed of CO and H2, while heavy metals are immobilized in glassy slag. The crude syngas is washed, shifted, desulfurized, and purified to produce high-purity H2 and CO2. In the crude syngas, HCl is transferred to wastewater and slag in the form of chlorides, while H2S is converted into sulfur for reuse. After pressure filtration of the black water from the gasifier, the filter cake and most of the filtrate are reused, while a small portion of the filtrate is treated to meet emission standards before being discharged. Slag can be used as a raw material for construction materials, and the exhaust gas is purified before being released to meet regulatory standards. The process for the coordinated disposal of biochemical sludge in space furnaces involves mixing the dried sludge with raw coal and discharging it from the vehicle, by controlling the amount of coal fed into the hoppers as well as the operating frequency of the conveyors used to feed coal into those hoppers. During the unloading process, it is mixed evenly in proportion and then spread into the raw coal bin. During the coal feeding process, the raw coal mixed with dried sludge is taken from the raw coal bin using a coal picker, conveyed to belt BC12 via belts BC10/BC11, and after being crushed and cleaned of impurities it moves onto belt BC13; from there it is transported to the raw coal bin of the pulverized coal gasification unit via belt BC14. The raw coal mixed with dried sludge, which enters the raw coal bin, is fed into the corresponding coal mills via coal feeders to produce coal powder for the pulverized coal gasification unit. This coal powder then enters the gasification furnace through a conveying system, where it undergoes gasification reactions with pure oxygen under specific temperature and pressure conditions. Currently, the sludge from Yitai Biochemical is sent to the Duogui Tara Hazardous Waste Treatment Center of Keling Environmental Protection Co., Ltd. for incineration.