Current operating status of various coal gasification technologies in China

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Current Operating Status of Various Coal Gasification Technologies in China Author/Source: Date: 2016-08-03 Clicks: 25 I. Current Operating Status of Fixed-Bed Gasification Technology The use of fixed-bed gasification technology in China began in the 1950s, primarily for gasifying lignite to produce raw material gas for ammonia synthesis. The former Yunnan People’s Liberation Army Fertilizer Factory was the first enterprise in China to use a coal pulverization pressurized gasification furnace, of which the furnace type was the first-generation Lurgi furnace. Currently, Yunnan Jiehua Group owns 14 Lurgi-type furnaces, one of which has been converted into a coal ash pressurized gasification furnace (BGL furnace), and successful operation began in 2006. After the mid-1980s, pressurized coal gasification units saw significant development in China. Enterprises such as Tianji Group, Lanzhou Gas Factory, Harbin Gasification Plant, and Yima in Henan all employed such units, which were primarily used for producing city gas, synthetic ammonia, methanol, dimethyl ether, natural gas, and coal indirect liquefaction. Among them, the 5 Mark-Ⅱ Ruhr-type units introduced by Lanzhou Gas Factory were mainly used for producing city gas; however, production has been halted due to limitations on customers ； In the late 1980s, Harbin Gasification Plant imported 5 PKM-type gasifiers (equivalent to 3rd-generation Lurgi reactors) from Germany ； The furnace type of the remaining enterprises is all Mark-Ⅳ coal pulverization pressurized gasification furnaces. In recent years, the enterprises that have adopted coal pulverization pressurized gasification units (Lurgi reactors) include Shanxi Lu’an, Xinjiang Guanghui, Inner Mongolia Datang International Keqi, Xinjiang Yili Qinghua, Guodian Chifeng Fertilizer, Jinmei Jinshi, Datang International Fuxin, Yili Xintian, and Henan Jinmei Tianqing. Among them, the gasification unit at Datang Keqi is the world’s first coal pulverization pressurized gasification unit operating at a pressure of 4.0 MPa; it was successfully put into operation for trial runs in May 2012 ； The gasification feedstock for the pulverized coal pressurized gasification unit of Jinmei Jinshi is Coal No. 15 from Jincheng, and feeding has been successfully carried out, proving that the pulverized coal pressurized gasification technology can be used to process Jincheng’s anthracite coal on its own. A common problem with the fixed-bed gasification process is the large volume of wastewater generated during the coal gasification process. This wastewater contains large amounts of tar, ammonia, phenols, and other substances. At present, there are no effective methods for treating these substances. Although it is possible to separate them using methods such as phenol and ammonia recovery as well as water-gas separation, and then send them to treatment facilities for processing, such treatment is difficult, and it is hard to meet the required discharge standards. The investment and costs associated with wastewater treatment are also high. In the operation of the fixed-bed gasification plants at Datang International’s Keqi project and Guanghui project in Xinjiang, issues of furnace corrosion occurred; in Inner Mongolia and Xinjiang, production targets could not be met due to the poor thermal stability of the coal. II. Current Operating Status of Fluidized Bed Gasification Technology. Fluidized bed gasifiers are valued and utilized by some enterprises due to their advantages such as simple structure, moderate operating temperature, ease of operation, high processing capacity, product gas free from substances like tar, wide range of applicable coal types, and the ability to use crushed coal with a size of less than 10 cm produced in coal mines. In 1993, the Shanghai Coking Plant introduced the U-gas gasification technology and equipment, consisting of 8 gasifiers – 6 in operation and 2 as backups. Each gasifier was designed to produce 20,000 m3/h of gas. The plant came online in April 1995, marking the world’s first industrial-scale installation using U-gas technology. From the trial production phase in 1995 until October 1996, a total of 15,000 gasifier-hours were operated, using Chinese Shenfu coal as the feedstock, in amounts of 50,000 tons in total. The actual operating results of this set of equipment failed to meet the design specifications, and meanwhile, as Shanghai replaced city gas with natural gas, the U-gas gasifier was shut down at the beginning of 2002. In 2005, SES Company entered into a partnership with Jinyong GCL (Inner Mongolia) Coal Chemical Co., Ltd., aiming to use U-gas gasification technology to produce 225,000 tons per year of methanol and 150,000 tons per year of dimethyl ether. In 2008, a U-gas pressure swing gasification unit with 2 units in total, 1 in operation and 1 as a backup, each having a coal feeding capacity of 400 t/d, was built at Aixins New Gas Co., Ltd. in Zaozhuang, Shandong Province, to supply synthetic gas as raw material for a methanol production plant with an annual output of 100,000 t. The first phase of the 300,000 t/a methanol project in Yima, Henan, utilized three U-gas pressure gasification units with a capacity of 1,200 t/d each, two in operation and one as a backup. The construction was completed mechanically in June 2012, and the first gasification unit was successfully tested in December of the same year. China began to introduce the TRIG circulating fluidized bed gasification technology in 2009; to date, two projects have adopted this technology. One is the IGCC renovation project carried out by Dongguan Zhongke (Zhengyu) Gasification Co., Ltd., which installed a TRIG gasifier with a coal feeding capacity of 1,700 t/d, while the other is the energy-saving and consumption-reduction renovation project of Boyuan Group in Sunit, which incorporated a TRIG gasifier with a coal feeding capacity of 1,200 t/d. At present, these two projects have not yet started operation. Fluidized bed gasification technology is a new type of gasification process in China; it is still in its initial stages, and there is a long way to go before it can be widely adopted. Due to the presence of a dilute phase, the gasification intensity of the fluidized bed gasification technology is not high. Furthermore, the carbon conversion rate is lower than that of fixed-bed and fluidized-bed gasifiers. III. Current Operating Status of Fluidized Bed Gasification Technology 1. Current Operating Status of Coal Water Slurry Gasification Technology Coal water slurry gasification technology is renowned in the industry for its stability and reliability. This gasification process requires that the ash melting point of the coal be below 1350°C (this requirement can be slightly relaxed for the Tsinghua furnace with water-cooled walls), and it also demands that the coal have good slurry-forming properties, with a requirement of over 58%; too low a value affects the economic efficiency of the gasification furnace’s operation. Texaco Gasification Technology in the United States (now GE Gasification Technology) has nearly 30 years of industrial experience in China, with almost 180 gasifiers in operation; it boasts a high level of industrialization and mature technology. Projects such as the production of city gas/methanol from coking coal in Shanghai, the production of synthetic ammonia/urea from coal along the Wei River, and clean energy projects in Pucheng are operating normally, with the longest continuous operation period reaching 180 days. East China University of Science and Technology has 10 years of industrial experience in multi-nozzle opposed water-coal slurry gasification technology; this technology is mature, features advanced processes, and operates stably, with a maximum continuous operation time of 90 days. Projects such as Shenhua Ningmei, Shanghai Coking, and Anyang Yingde all utilize this multi-nozzle opposed water-coal slurry gasification technology. The main drawback of this type of gasification technology is its high requirements regarding coal quality; the burners and refractory bricks in the gasification furnace tend to develop problems and need to be replaced frequently, resulting in shutdowns for maintenance every 1 to 2 months on average. Multi-material slurry gasification also has over a decade of industrial experience; the technology is mature and operation is stable. Compared with other coal-water slurry gasification methods, the Tsinghua furnace has a shorter period of industrial operation, and its technology requires further improvement. 2. Current operating status of dry coal powder gasification technology. Pressurized dry coal powder gasification technology is the mainstream in today’s coal chemical industry, and it exhibits relatively wide adaptability to different types of coal. The ash fusion point T4 of the coal to be fed into the furnace is required to be less than 1400°C, the silicon-aluminum ratio to be greater than 1.6 (this requirement can be relaxed slightly in the case of a downward water quenching process), and the operating window to be greater than 120°C. GSP gasification has several years of industrial operation experience in China; at present, all projects are operating normally, with the longest continuous operation time reaching 130 days. Examples include the 830,000 t/a dimethyl ether project of Ningxia Coal Industry Group, and the \"Jincheng 3052 project\" of Shanxi Lilac Coal Chemical Co., Ltd. Shell’s powder gasification technology has 15 years of industrial experience in China, and it is one of the most advanced gasification technologies in the world. Between 2000 and 2009, Chinese companies installed 23 Shell gasification units; however, due to issues such as the need to import certain equipment and high operational requirements, only half of these units were able to be commissioned for operation, and their performance did not meet expectations as they struggled to adapt to local conditions. To address the long-standing controversies in the country regarding the frequent operational issues that arose after Shell’s facilities went into operation, Shell and the end-users have made unremitting efforts to accelerate the localization of components, strengthen technical exchanges and intellectual property protection, and ensure stable operations; as a result, stable industrial operations have now been achieved. Projects such as the Datang Duolun coal-to-olefins project, the Yunnan Tianan ammonia synthesis project, the Henan Hebi methanol project, and the Shenhua coal-to-oil project have achieved continuous high-load operation of a single furnace for over 120 days, making 100-day operation a routine practice ； Multiple Shell gasification units at Shuanghuan, Liuhua, Yongcheng, and other locations have been in operation for a total of over 320 days, with the highest record being 341 days. It has been eight years since the space furnace was put into industrial use; through continuous practice and improvement, a great deal of experience in design and operation has been accumulated, the technology has become quite mature, and its performance is good. Other gasification processes for pulverized coal, such as the two-stage furnace and the Dongfang furnace, have only been applied in 1–2 projects; their industrial operation time is short, and the technology still needs to be improved and refined. The Ningmei furnace has not yet been started; it remains to be seen.