China’s first high-alkali medium circulating fluidized bed gasification unit has been successfully put into operation

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China’s first set of high-alkali coal-based circulating fluidized bed gasification units has been successfully put into operation. Author/Source: Zhongke Hefei Gasification. Date: September 24, 2020. Clicks: 9. At 18:06 on the 18th, urea products were successfully produced in the 4060 project of Xinjiang Yihua Chemical Co., Ltd. (hereinafter referred to as “Xinjiang Yihua”), marking the successful operation of the gasification plant built by Zhongke Hefei Gasification Technology Co., Ltd. (hereinafter referred to as “ZHGE Gasification”). This project is an upgrade and renovation of the gas generation section of Xinjiang Yihua’s ammonia synthesis system; it uses 3 sets of atmospheric-pressure circulating fluidized bed oxygen-enriched gasifiers, each with a capacity of 600 Nm3/h, to replace the original 20 sets of atmospheric-pressure fixed-bed oxygen-enriched continuous gasifiers used for producing syngas. It represents the largest circulating fluidized bed gasification unit of its kind currently in use in the ammonia synthesis industry in China, and it is also China’s first circulating fluidized bed gasification system that uses high-alkali coal as raw material for syngas production. Xinjiang Yihua Chemical Co., Ltd. is a wholly-owned subsidiary established by Yihua Group in Jimsar County, Changji Hui Autonomous Prefecture, Xinjiang, in order to implement the strategy of converting the region’s abundant resources into valuable products and to promote local economic development. It is also the first large-scale enterprise to set up operations in the Zhundong area of Xinjiang. Its production capacity is 400,000 tons of synthetic ammonia and 600,000 tons of urea. Previously, Yihua’s gas production unit used smokeless lump coal from other regions as raw material, and synthetic gas was produced using 20 atmospheric-pressure fixed-bed oxygen-enriched continuous gasification furnaces. This approach had various drawbacks, including high costs for raw coal, low load per furnace, difficulties in dealing with tar, and high levels of waste emissions, all of which did not meet environmental standards. The Jundong region is rich in coal resources, but most of it is high-alkali coal, which exhibits characteristics such as strong fouling tendency, easy coking, large fluctuations in ash melting point, and poor slurry-forming properties, making it unsuitable for gasification processes that utilize fixed-bed slag, fluidized-bed coal slurry, or fluidized-bed pulverized coal. Guided by the principle of making full use of local coal resources and taking into account the features of this high-alkali coal, gasification researchers, after conducting feasibility studies, designed the use of oxygen-enriched fluidized-bed gasification technology to build three sets of pulverized coal gasifiers, each with a capacity of 60,000 m3. This process does not generate hazardous waste such as tar or phenol-cyanide wastewater. Additionally, customized designs such as optimizing the air supply for the gasification agent, establishing a high-throughput return material cycle, and enhancing waste heat recovery help to reduce material coking and minimize heat loss. The successful commissioning of this project will **reduce the gas production costs at Xinjiang Yihua; the cost per ton of ammonia can be lowered by 200 to 400 yuan. The high-temperature steam generated as a by-product can serve as a heat source for the factory’s production lines. Since entering the site after the New Year, the project team has actively overcome various challenges such as the complex climate in Xinjiang, time zone differences, and pandemic control measures, and has successfully completed tasks such as high and low temperature furnace drying, the three-inspections and four-fixes procedures, PSSR audits, individual unit tests, joint tests, and no-load tests. On September 6, the gasification unit was successfully ignited, marking the start of the feeding and trial operation phase. On September 8, the parameters of the syngas met the required standards (the effective gas volume was ≥64, which satisfied the requirements for subsequent ammonia synthesis). On September 16, the synthetic helium system produced liquid helium of satisfactory quality. On September 18, urea products were ready for delivery. During the trial production period, the gasification unit operated stably as a whole, with uniform furnace temperature (axial temperature difference ≤ 10), and flexible load adjustment. The gasification unit, waste heat recovery unit, dust removal unit, cooling water unit, slag discharge unit, coal conveying unit, ammonia vaporization unit, etc., all meet or even exceed the design specifications. During operation, the load should be ≥95%, the efficiency of cold gas production should be ≥76%, the preheating temperature of the gasifying agent should be ≥700–400°C, and the output of medium-pressure steam should be ≥60 tons/h. This system represents the most advanced new gasification technology in the industry nationwide, designed to suit the coal quality available in the Zhundong Development Zone. At the same time, to produce ammonia and urea, coal gasification is the first step and the key stage in the entire process. ”Yang Xiaoqin, a member of the Party Committee and chief engineer at Xinjiang Yihua, said that this set of equipment, through its innovative processing methods, overcomes the various challenges associated with Zhundong sub-bituminous coal, such as high sodium and potassium content, high moisture levels, low ash content, low ignition temperature, oil content, special viscosity-temperature properties, and poor slurry-forming ability. As a result, it becomes the most suitable choice for large-scale new types of coal gasification processes that use Zhundong sub-bituminous coal as raw material. The successful commissioning of the Yihua project has fully demonstrated the strong adaptability of CGAS technology to different types of coal. It provides a practical process solution for small and medium-sized ammonia synthesis enterprises to reduce their coal consumption costs, and it also offers technical and equipment support for the efficient and clean utilization of the large reserves of high-alkali coal in Xinjiang. This project is the second one in the field of ammonia synthesis to be successfully operated using CGAS technology. The advantages of this technology – such as low operating costs, good environmental benefits, and short renovation periods – become even more evident in similar projects. In the future, Zhonghe Gasification will continue to expand the application of CGAS technology in this field, drive technological innovation in the industry, and provide efficient, environmentally friendly, and cost-effective solutions for ammonia synthesis and coal chemical enterprises.