The first technical upgrade using desorbed gas as a substitute for furnace gas was successful

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First successful retrofit using desorbed gas as a substitute for furnace gas Author/Source: Sinochem News Network Date: April 8, 2020 Clicks: 6 Full utilization of waste gas leads to a significant increase in hydrogen production According to a report from Sinochem News Network, a reporter from China Chemical Industry News learned from Shaanxi Dongxinyuan Chemical Co., Ltd. that on March 30th, the company used desorbed gas along with furnace gas as fuel in its carbonization process. After two days of continuous process adjustments, the amount of desorbed gas used in combustion increased from zero to 10,000 cubic meters per hour, while the volume of gas sent back to the furnace decreased by 8,000 cubic meters per hour; the gas saved in this way was entirely utilized for hydrogen production. This technological upgrade will replace furnace gas with desorbed gas to increase hydrogen production, reduce the load on the semi-coke plant, and also meet the hydrogen production needs. 　　Previously, coal was processed through dry distillation (pyrolysis) to produce semi-coke, tar, and raw gas. The semi-coke industry generally used recycled gas as fuel for the carbonization furnaces; this recycled gas accounted for 40% to 50% of the total gas produced by those furnaces, and the hydrogen contained in it was wasted. 　　“Gas generation is a key step in the coal chemical industry, and hydrogen is a valuable resource. If the waste gas (desorption gas) obtained after hydrogen extraction from waste gas is used as a fuel in combination with other fuels, it is possible to save the gas intended for hydrogen extraction processes, thereby achieving comprehensive utilization of resources to the fullest extent and avoiding waste gas emissions. ”Li Yajun, deputy general manager of Dongxinyuan Company, said that this is the first time in China that desorbed gas has been used to replace furnace gas, thereby driving the transformation and upgrading of the semi-coke industry. 　　It is reported that Dongxinyuan Company owns the first oxygen-based hydrogen production facility of its kind in the country; the waste gas generated after hydrogen extraction (desorption gas) still contains CO, and its calorific value can reach around 1,500 kcal. The desorbed gas with a higher calorific value is successively used to replace lignite in drying coal gas, to replace liquefied gas in heating furnaces, and to be fed into circulating fluidized bed boilers for co-firing. On this basis, Dongxinyuan Company proposed a technical improvement approach involving the use of exhaust gas as a substitute for coal gas in the furnace. 　　At the beginning of 2020, the adsorption resistance-reduction modification for oxygen-based hydrogen production was successfully completed, allowing the hydrogen production facility to handle gas with a lower hydrogen content. After the last remaining shortcoming was addressed, at the beginning of March Dongxinyuan Company developed a technical upgrade plan to use desorbed gas as a substitute for furnace gas, and the renovation work was completed in just over half a month. On March 30, the desorbed gas was fed into the carbonization furnace for mixed combustion, with immediate results: the amount of gas exported from the carbonization furnace increased, coal consumption decreased, and the consumption of gas recycled back to the furnace dropped from 19,000 cubic meters per hour to 14,000 cubic meters per hour. 　　Li Yajun explained that they are adjusting the operating conditions of the system to maintain stability in the blending process, and are also experimenting with ways to gradually increase the amount of gas recovered from the furnace that is used in combustion; it is expected that within a week, this gas will be able to completely replace furnace gas. At that time, all the saved blast furnace gas will be sent to the hydrogen production unit for hydrogen extraction, allowing the amount of hydrogen produced to increase significantly. This will further enhance the effects of the technological upgrades and pave the way for a new approach to the clean and efficient utilization of coal based on its different quality levels. 　　This technology allows an increase in gas production for hydrogen production without the need to add additional anthracite production facilities, thereby reducing the amount of gas consumed by the carbonization furnaces themselves. It also enables flexible adjustment of the anthracite production ratio, which helps to reduce costs and improve efficiency. With the current sluggish market for semi-coke and poor sales prospects, this technical upgrade can reduce the production of semi-coke and coal consumption, while ensuring that the hydrogen production level remains unchanged and preserving the oil production capacity of the coal tar hydrogenation unit. Currently, the company has reduced the operating load of 12 carbonization furnaces with a capacity of 100,000 tons per year by 7%.