Comprehensive Overview of Technological Innovation Paths for Gasification Units

Thread Content

A Comprehensive Overview of the Technological Innovation Paths for Coal Gasification Equipment Author/Source: Date: 2016-08-11 Clicks: 10 Coal gasification technology and equipment constitute an essential foundation for the clean and efficient conversion and utilization of coal. Thanks to continuous innovation and technological improvements in recent years, gasifiers in China are now competing fiercely among themselves. Understanding the development trends in coal gasification technology and selecting gasification equipment that is suitable for the type of coal used, meets the requirements of the products produced, features low energy consumption and low investment costs, is mature and reliable, and is environmentally friendly and safe, is an important direction for the healthy development of the coal chemical industry. At the 2016 China New Coal Gasification and Related Technology Innovation Development Conference held in Beijing on July 29, experts present offered such insights and suggestions. Various types of gasifiers keep emerging. “All kinds of gasifiers are important tools and core equipment for gasification; they are widely used in China, with a high level of industrial maturity, a variety of technologies available, and a large number of such gasifiers in use.” The number of advanced large-scale fluidized-bed pressurized gasification units in use in China has reached over 300. ”Han Hongmei, deputy director of the Energy and Chemicals Division at the Petroleum and Chemical Industry Planning Institute, explained. 　　It is understood that gasifiers can be classified into three categories based on the way materials come into contact: fixed-bed (moving-bed), fluidized-bed (boiling-bed), and gas-flow bed. The mainstream technologies for coal pulverized pressurized fixed-bed gasifiers (with solid/liquid slag discharge) include the Lurgi furnace, Suiding furnace, BGL furnace, Yunding YM furnace, etc. The Ende coal gasification technologies, which are widely used in fluidized bed systems, include China’s ICC furnace, Ende furnace, and Koda furnace (Newpower), among others. The mainstream technologies for dry pressurized pulverized coal gasification in fluidized bed systems include the Shell furnace, GSP furnace, Corin furnace, two-stage furnace (TPRI), HT-L furnace, Dongfang furnace, Huali furnace, Wuhuan furnace, Ningmei furnace, Liuhua-Qiyao furnace, Shenggu furnace, Jinzhong furnace, and others. The mainstream furnace types for wet coal slurry gasification in gasized beds include GE-TCGP, opposed four-nozzle furnaces, the Tsinghua furnace, and the multi-feedstock slurry furnace developed by the Northwest Research Institute for multi-feedstock slurry gasification. 　　At present, our country has achieved remarkable results in the innovation of gasifiers. Zhu Yuying, assistant general manager of Aerospace Changzheng Chemical Engineering Co., Ltd., said that the HT-L furnace developed by the aerospace company has been validated through long-term operation. The key equipment such as the gasification furnace, burners, slag breaker, hot air furnace, safety valves, special valves (oxygen valve, coal powder valve, slag locking valve, coal powder control valve, directional valve, black water control valve), high-pressure wear-resistant pumps, and high-speed pumps have all been domestically produced, with independent intellectual property rights secured. 　　Liu Haifeng, a professor at East China University of Science and Technology, explained that the single-nozzle cold-wall coal gasification technology (SE Dongfang Furnace), developed jointly by Sinopec Ningbo Engineering Company, Ningbo Research Institute of Technology, and East China University of Science and Technology, has been put into operation at a 1,000-ton/day demonstration plant operated by Yangzi Petrochemical in Nanjing, Jiangsu. The 1.7 million tons/year coal-to-olefins project undertaken by Zhongan United is currently under design, with 7 gasification units of 1,500 tons/day to be used. This furnace type features a tube-type water-cooled wall, as well as an integrated burner that combines ignition, heating, and process control functions. The staged purification unit consists of a mixer, a cyclone separator, and a water wash tower. The evaporative hot water tower serves both flash evaporation and heat exchange purposes, addressing issues such as black water clogging the heat exchangers and affecting heat transfer efficiency. 　　The Jinhua furnace (syngas/steam co-generation gasification furnace), jointly developed by the Shanxi Clean Energy Research Institute of Tsinghua University, Shanxi Yangmei Fengxi, and Shanxi Yangmei Chemical Machinery (Group) Co., Ltd., was successfully put into operation on April 1, 2016, at the Linyi branch of Yangmei Fengxi. Using Shanxi’s \"high-carbon, high-ash, high-sulfur\" coal as raw material, it has been operating stably for over 100 days. This gasifier can effectively prevent slag clogging and ash accumulation ； The unique structural design reduces the proportion of configurations subject to heat from both sides, resulting in a smaller equipment size and lower costs ； Recovering the heat from the high-temperature syngas and producing high-temperature, high-pressure steam can improve the energy conversion efficiency of the gasifier. 　　Survey data show that by the end of 2015, excluding fixed-bed atmospheric gasifiers, a total of 392 pressurized coal gasifiers had been put into industrial use in China. Among these, 120 fixed-bed coal pulverization pressurized gasifiers were the most widely used, accounting for 77.9%; 20 fluidized-bed Ensdorf coal gasifiers accounted for 55.5%, while 75 gas-flow bed GE coal slurry gasifiers accounted for 37.1%. Technological innovation to address weaknesses: Han Hongmei said that gasification technology has undergone decades of exploration and practice, with continuous improvements, and its technical level is now quite high. However, as the fields of application and geographic areas for coal gasification in China expand, there is a greater need for diverse coal gas compositions; there are more types of coal, and the variations in coal quality become more complex. With increasing demands regarding environmental protection and safety, coal gasification technology still needs to be further improved and enhanced, taking into account its own characteristics as well as the problems that arise during operation. 　　It is reported that the key issues that need to be addressed for the existing gasification furnace types include: reducing the purchase of patented equipment and increasing the degree of localization of critical equipment, optimizing the design of processes and control systems, reducing software costs (patent fees + PDP fees + technical service fees), raising the gasification pressure of water-coal slurry to 6.5–8.7 MPa, further increasing the scale of equipment to allow for larger amounts of coal to be used, raising the pressure level of the by-product steam, optimizing the quenching and dust removal systems, recovering energy, optimizing the method of quenching syngas, effectively treating hazardous wastewater, optimizing the ash water treatment system, improving the ash water recycling process, improving coal gas washing methods, reducing the amount of dust emitted, lowering the carbon content in slag, reducing the discharge of fine slag, and intensifying research on the utilization of fine slag. 　　“The future innovations in gasification furnace equipment lie in increasing the level of domestic production, reducing investment costs, raising the gasification pressure, developing large-scale gasification equipment, and improving energy efficiency, water conservation, and environmental protection standards. ”Han Hongmei said. For example, as of June 2016, China had introduced 28 Shell waste boiler process gasifiers. Currently, for the 10 key equipment in the Shell process, except for the coal powder velocity meter and densitometer, there are domestic manufacturers with certifications or those that are in the certification process. In the future, it is also necessary to accelerate the localization of key equipment, which can **reduce the investment and operating costs of gasification units, as well as improve the level of domestic equipment manufacturing. 　　According to interviews with journalists, the future direction of innovation in gasification technology will focus on areas such as catalytic gasification and underground coal gasification. Han Hongmei said that catalytic gasification can reduce the gasification temperature by 200°C to 300°C, enabling mild gasification and directed conversion; currently, focus is needed on researching catalyst types, catalytic reaction mechanisms, and catalytic gasification processes. The current focus of underground coal gasification technology is on refining the technical details, including process control, auxiliary devices/equipment for underground gasification, ignition technology, and gasifier design ； Key peripheral technologies, such as gasification recovery and pollutant control, should also be strengthened. 　　In addition, there are other research directions such as hydrogen gasification, biomass catalysis, staged gas flow bed coal gasification (coupled with high-temperature shift), coal gasification in blast furnace slag, supercritical water gasification, secondary gasification of fly ash, and thermal integration of coal gasification with other processes (such as integration with methanation). Gasification islands are gaining prominence. With the rapid development of coal gasification technology, the expansion of industrial parks (large enterprises), as well as industrial restructuring and upgrading, it has become a trend to use specialized gasification islands to supply industrial parks, especially large enterprises, with large quantities of high-quality, low-cost industrial gases such as syngas, hydrogen, and carbon monoxide. 　　Han Hongmei stated that a professionally operated gasification island is the best solution for addressing changes in coal quality, ensuring a stable supply of industrial gases on a large scale, and addressing the issues related to coal utilization and its environmental impact. 　　Gasification islands are classified into enterprise-level and park-level based on the size of the customer base, into syngas-type (CO+H2, H2, CO) and industrial gas-type according to the composition of the gas supplied, and further into chemical industry-type (refining/coal chemical other chemical industries, etc.) and other industrial-type (ceramics/construction materials/cement, etc.) depending on the industries served. The gasification island model, which provides gas supply to gas-consuming enterprises on a wide scale and in a universal manner, is attracting increasing attention and interest from more and more enterprises and industrial parks due to its advantages in terms of scalability, specialization, and flexibility. 　　“In industrial parks with a large number of enterprises and high demand for industrial gases, the construction and operation of large-scale gasification islands enable efficient and centralized production operations as well as unified scheduling of production services. This avoids the drawback of repeated construction of small-scale gasification units resulting from individual enterprises building such units on their own, thus facilitating coordinated management and long-term development of the park. ”Han Hongmei said. 　　It is reported that large petrochemical parks at home and abroad have gradually adopted the gasification island model. The large-scale modern coal chemical production base that is being planned in our country will also incorporate the planning of large-scale gasification islands. In July 2014, the Zhongyuan Dahua Gasification Island project, with a total investment of 3 billion yuan, began construction in the Puyang Development Zone. The construction period is expected to be 36 months. Using coal powder as raw material and advanced pressurized coal slurry gasification technology, the project includes facilities for syngas purification and air separation, aiming to produce key raw materials for downstream coal chemical products. Once fully completed, the project is expected to generate an annual output value of 2.8 billion yuan and tax revenues of 220 million yuan. 　　The gasification unit of the Yuheng Coal Chemical Project at Yulin Energy and Chemical Co., Ltd., a subsidiary of China National Coal Group Shaanxi Company, uses a GE900 cubic foot gasification process at a pressure of 6.5×106 Pa. There are 5 gasifiers in operation with 2 as backups; the total daily coal input is approximately 8,000 tons. The gasification facility was successfully commissioned with its first batch of feed in late April 2014. Han Hongmei said that for a specialized gasification plant, it is necessary to select appropriate processes such as fluidized-bed gasification, gas-flow bed gasification, or fixed-bed oxygen-enriched gasification based on the specific requirements. At the same time, an economic analysis of the entire process must be carried out taking into account the availability of coal sources, that is, considering \"coal source + gasification technology + product price\".