【Ten Years of Great Progress in Chemical Engineering Technology】Development and Application of Agents for Reducing Hardness and Emissions in Coal Gasification Black Ash and Water, 2015–2020

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The chemical industry has seen tremendous development over the past decade; let’s praise the prosperity and strength of modern China. By sharing our insights, we can encourage more people to participate, thereby making discussions more lively. HaiChuan becomes even better with your involvement – we welcome everyone to join in the forum discussions. It’s hot in July, so be careful to prevent fires. ---------------------------------------------- Gasification technology is a key technology; its performance determines whether the subsequent chemical processing or power generation systems can operate safely, stably, for long periods of time, at full capacity. Currently, the hardness, alkalinity, and suspended solids levels in the gasification slag water system are generally high. To prevent the formation of calcium magnesium carbonate scale in this water, a scale-inhibiting and dispersing agent needs to be added to the ash water after flocculation. Relying on the Shell-type quenching gasification furnace of Yuntianhua Hulunbuir Jinxin Chemical Co., Ltd., as well as the ash water treatment systems associated with the multi-nozzle gasification furnaces of Jiangsu Supor Group Co., Ltd., Taizhou Jiuyun Chemical Technology Co., Ltd. conducted research on the factors affecting the characteristics of gasification black ash water by combining laboratory studies with industrial tests. It developed efficient ash water dispersants and flocculants. Through a dual-system approach of scale inhibition and dispersion followed by flocculation, different chemicals were added at various points in the process units; by applying chemicals at different locations and at specific points, it was possible to prevent the formation of scale. From an overall engineering perspective related to coal gasification slag and ash water management, this approach enabled the stable, efficient operation of the gasification ash water system without significant hard scale formation. The quality of the ash water (such as hardness and COD levels) and the amount of waste discharged were much lower compared to similar systems. On June 12, 2020, the China Petroleum and Chemical Industry Federation organized experts to hold a video appraisal meeting on the scientific and technological achievement of \"Development and Application of Agents for Reducing Hardness and Emissions in Coal Gasification Black Ash Water\", which was developed by Taizhou Jiuyun Chemical Technology Co., Ltd. The appraisal committee is headed by Academician Han Buxing from the Institute of Chemistry, Chinese Academy of Sciences. The members include Sun Baoци, deputy director of Sinopec Gasification Technology Center; Professor Wang Yifei from East China University of Science and Technology; Professor Yang Wenzhong from Nanjing Tech University; Xiao Xiaoyu, deputy chief engineer at China Wuhuan Engineering Co., Ltd.; Zhang Tao, deputy general manager of Shandong Yankuang Guotuo Technology Engineering Co., Ltd.; Dong Qiao, chief engineer at Yangmei Group Cangzhou Zhengyuan Fertilizer Co., Ltd.; and Researcher Peng Shu from Changzheng Chemical Engineering Co., Ltd. The meeting was chaired by Wang Xiujiang, deputy director of the Science, Technology and Equipment Department of the China Petroleum and Chemical Industry Federation. Chen Jianhua, General Manager of Taizhou Jiuyun Chemical Technology Co., Ltd., the entity responsible for completing the project, presented the work report and research report. Bu Jianjun, Plant Manager of Jiangsu Suopu Group’s methanol plant, and Yuan Kunneng, a process engineer from Hulunbuir Jinxin Chemical Co., Ltd., delivered reports on the application of these results from the production sites respectively. By comparing the water quality and wastewater volume for different chemicals and service providers used on the same unit, as well as those from different service providers on similar units, the evaluation committee concluded unanimously that this technology addresses the challenges associated with treating high-hardness and high-turbidity wastewater generated in coal gasification processes. Through approaches such as multiple points of chemical addition using different chemicals at various locations, adaptive scale-inhibiting and dispersion agents for ashwater, and tracing technologies, it has developed a combined strategy for reducing hardness and wastewater volume. This approach effectively mitigates scaling and deposition throughout the system, contributing to the stable, efficient, and reliable operation of coal gasification units. It has been successfully applied in both pulverized coal and coal slurry gasification technologies, yielding significant results in reducing hardness and wastewater volume; it is thus at the leading level in China in the field of treating coal gasification wastewater. It is understood that the true value of this technology lies in its role as a pioneer in using graywater dispersants to actively regulate water quality. Previous techniques for preventing scaling in graywater relied on the approaches used in industrial circulating cooling water systems, which involved retaining hardness ions in the water and reducing hardness through wastewater discharge; as a result, a large volume of wastewater was generated. Graywater differs significantly from industrial circulating cooling water and should be classified as part of the water used in coal gasification processes. Jiuyun’s combination of technologies for reducing hardness and emissions has developed methods for evaluating the performance of industrial water treatment chemicals, methods that can also be applied to the treatment of industrial circulating cooling water.