Overview and Development Trends of China’s Coal Chemical Industry

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An overview of China’s coal chemical industry and its development trends. Coal chemical processing includes the coking, gasification, and liquefaction of coal. Coal coking, which is mainly used in the metallurgical industry, and coal gasification for the production of synthetic ammonia represent traditional coal chemical industries. With the continuous development of the socio-economy, these industries will see further growth. At the same time, coal liquefaction, coal-based alternative liquid fuels, and coal gasification for power generation – all of which aim to produce clean energy – are also attracting increasing attention as part of coal chemical or coal chemical-related energy technologies, and they will become the main directions for the industrial development of new coal chemical processes. Developing a new type of coal chemical industry is of great significance for adjusting the industrial structure of the coal industry and its comprehensive development. ? 1 Overview of the Development of the Coal Chemical Industry? 1.1 Coal Coking The coking industry is the most developed and representative sector within the coal chemical industry; it also serves as a key supporting industry for blast furnace iron production in the metallurgical industry and for casting processes in the machinery industry. Currently, the global coke production is approximately 320–340 million tons per year, with about 450 million tons per year of raw coal being consumed directly. Affected by factors such as adjustments in global steel production, advancements in blast furnace injection technology, environmental protection measures, and rising production costs, the mechanized coking capacity in industrially developed countries is on the decline; currently, the international trade in coke amounts to 25 million tons per year. At present, China’s coke production is around 120 million tons per year, the highest in the world, and the raw coal consumed directly accounts for 14% of the country’s total coal consumption. 　　There are over 750 mechanized coke ovens of various types across the country, with an annual designed coke production capacity of around 90 million tons per year. Among these, large and medium-sized coke ovens with a carbonization chamber height of 4m to 5.5m or more account for approximately 80% of the total production. China has achieved domestic production of large-capacity coke ovens (with a chamber height of ≥6m). The technology for gas purification has reached world-class standards, while dry quenching of coke, on-ground dust treatment systems, and wastewater treatment have all entered the practical application phase. The quality of coke has improved significantly, and the refining technology for its main chemical products has reached or come close to world-class levels. 　　Coke has become one of China’s main export products, with its export volume increasing year by year; it reached 1,500 tons per year in 2000, making China the largest exporter of coke in the world. 　　Since the 1980s, coking production in the coal industry has developed gradually; some plants were built with the main purpose of supplying artificial gas to cities or mining areas, while others produce coke as their primary product. The common problems in coking production within the coal industry are as follows: the coke ovens are small in size, with most being of medium and small scale; due to limitations imposed by the types of coal produced in the mining areas, it is difficult to improve the quality of coke. There is limited use of new technologies such as dry quenching of coke and centralized treatment of dust, and most enterprises lag far behind similar factories in other industries in terms of technological advancement and modern management practices. ? 1.2 Coal gasification and its synthesis technologies? 1.2.1 Coal gasification Coal gasification technology is the most important core technology for the industrial development of coal chemical industry. There are currently 414 large-scale gasifiers in commercial operation around the world, with a rated gas production capacity of 446×106 Nm?3/d. The top 10 gasification plants use three types of reactors: Lurgi, Texaco, and Shell; the feedstocks are coal, residue oil, and natural gas, while the products include F-T synthesized oil, electricity, or methanol. Gasification technology is widely used in China in industries such as chemicals, metallurgy, machinery, and building materials, as well as in enterprises that produce city gas. There are approximately over 9,000 gasifiers in use, with fixed-bed gasifiers being the most common type. Over the past 20 years, the pressurized Lu Strange furnace and Texaco water-coal slurry gasifier introduced into our country have been mainly used for producing synthetic ammonia, methanol, or city gas. ? The development and role of gasification technology have attracted attention from the domestic coal industry. “During the Ninth Five-Year Plan period, Yankuang Group collaborated with domestic universities and research institutions to develop a pilot-scale unit for a 22t/d multi-nozzle water-coal slurry gasifier, and conducted evaluation tests on it. ? The results show that the effective gas composition reaches 83%, and the carbon conversion rate is >98%, which are 1.5%～2% and 2%～3% higher respectively than those of the Texaco production unit under identical conditions ； Both specific coal consumption and specific oxygen consumption are 7% lower than those of Texaco. This achievement marks a breakthrough in the advanced gasification technology independently developed by our country. 　　1.2.2 Coal gasification for ammonia synthesis Using coal as a raw material and employing coal gasification-ammonia synthesis technology is the main method for fertilizer production in China. At present, more than 800 small and medium-sized fertilizer plants in China use the water-gas process, with a total of around 4,000 gasification units. These units consume over 40 million tons of raw coal (or coke) each year, and the ammonia produced accounts for approximately 60% of the country’s total ammonia output. The types of gasifiers used for fertilizers are mainly of the UGI type and the Д type from the former Soviet Union; their diameter ranges from 2.2 m to 3.6 m. These types of gasifiers are outdated and technologically obsolete. The pressurized Ruchi furnace and the Texaco furnace are the main types of furnaces introduced in recent years for ammonia synthesis production. Few countries abroad use coal as a raw material for producing fertilizers; generally, oil or natural gas is used instead ； In China, due to industry segmentation and the fluctuations in the market for coal-based synthetic ammonia in recent years, only a few coal groups have enterprises (or production lines) for gasification to produce synthetic ammonia (fertilizers). 1.2.3 Gasification for the production of liquid fuels (indirect liquefaction) In the 1950s, the South African company SASOL began building the SASOLI plant for gasification and the production of synthetic fuel oils. By the end of the 1970s and the early 1980s, the SASOLII and SASOLIII plants were constructed, resulting in what is now the world’s largest enterprise for producing liquid fuels through gasification. SASOL processes approximately 45 million tons of raw coal per year, producing around 7.6 million tons of synthetic products annually, of which 60% is fuel oil. ? Our country has been conducting research and development on indirect liquefaction technology since the 1950s. Starting in the 1980s, the Shanxi Coal Chemistry Institute of the Chinese Academy of Sciences systematically carried out technical development for the use of iron-based catalysts in Fertig process to produce gasoline, and completed an industrial-scale experiment on coal-based synthetic gasoline with a capacity of 2000 tons per year ； In the development of synthesis processes for cobalt-based catalysts, systematic research and development efforts began in the 1990s, yielding phased results with the creation of three types of cobalt-based catalysts for diesel synthesis. Small-scale tests were conducted on catalysts and reactors for the new slurry-bed synthesis process. During the 10th Five-Year Plan period, development and testing of a 1,000 t/a indirect liquefaction plant were initiated, and an industrial-grade coal-based synthetic oil process software package was developed. ? While carrying out technological development, domestic coal companies have made significant efforts to introduce mature technologies and build coal indirect liquefaction plants. Pingdingshan Coal Industry Group and Ningxia Taixi Group have conducted coal type evaluation tests and pre-feasibility studies for the construction of a commercial demonstration plant for indirect liquefaction. They have also carried out extensive preliminary work regarding technology acquisition, financing, and project approval; at present, the project is in the assessment phase. 　　1.2.4 Synthesis technologies for other coal gasification products The synthesis of various specialty chemicals from syngas produced by coal gasification depends on the synthesis technology used. There has been extensive research and development on such technologies both domestically and internationally, with some of them already in commercial operation. ? Methanol is an important chemical raw material and can also be used as a substitute fuel for engines. The world’s methanol production capacity is 35 million tons per year, with an actual production of around 29 million tons per year. China’s methanol production capacity is approximately 3 million tons per year, with over 140 manufacturers in the industry; more than 50% of them use coal as a raw material in their production processes. Compared with foreign countries, domestic methanol production facilities are of smaller scale and use outdated production processes; in particular, the processes that rely on coal as a raw material are complex and costly, resulting in a lack of competitiveness. The Jinzhong area in Shanxi has been carrying out demonstration projects for methanol-powered vehicles for many years. As another alternative liquid fuel, the technological development of dimethyl ether has attracted attention; researchers believe that it can serve as a substitute for diesel fuel in vehicles, as well as a replacement for LPG as a fuel for household use. The global production of dimethyl ether is approximately 150,000 tons per year, mainly produced through the methanol dehydration process. Recent technological advancements involve the one-step synthesis of dimethyl ether from synthetic feed gas under certain conditions. 1.3 Direct coal liquefaction The process of directly obtaining liquid products by heating coal and subjecting it to pressurized hydrogenation is known as direct coal liquefaction. By the end of World War II, the direct liquefaction plants established in Germany, which used lignite and bituminous coal as raw materials, had achieved a production capacity of 4.2 million tons per year. 　　Since the 1970s, major industrialized countries such as Germany, the United States, and Japan have successively developed new processes for the direct liquefaction of coal, and completed industrial-scale testing as well, thereby laying the foundation for commercial production. Notable technologies include Germany’s IGOR process, the U.S.’s H-Coal process, and Japan’s NEDOL process; all three of these processes have been tested at a scale of hundreds of tons per day. China began research on direct coal liquefaction technology in the late 1970s. The Beijing Coal Chemistry Institute of the China National Coal Science Research Institute conducted 53 operation tests on 27 types of coal using a plant with a capacity of 0.1 t/d. It developed highly active catalysts for coal liquefaction, carried out research on improving the quality of coal liquefaction oil, and completed experiments on converting the crude oil obtained from coal liquefaction into qualified gasoline, diesel, and aviation kerosene. “During the Ninth Five-Year Plan period, pre-feasibility studies for the construction of coal direct liquefaction plants at Shenhua, Yilan in Heilongjiang, and Xianfeng in Yunnan were completed in collaboration with relevant departments and companies in Germany, Japan, and the United States. At present, the construction of the first-phase 2.5 million tons per year commercial demonstration plant for direct coal liquefaction by Shenhua Group is in the preliminary engineering stage; the first production line is expected to be completed in 2005, with an annual output of 800,000 tons of oil products. 　　1.4 Coal Gasification Combined Cycle Power Generation (IGCC) IGCC is a combined cycle power generation system based on coal gasification; this technical approach integrates advanced coal gasification techniques with power generation methods in order to achieve efficient, low-pollution, and large-scale coal power generation. ? Starting from the 1970s, some industrially developed countries began to carry out systematic research and development on IGCC technology. Countries such as the United States, the Netherlands, and Spain have successively built industrial-scale IGCC demonstration units, with a net power generation efficiency of 43%–45%. The emissions of pollutants and water consumption are only 1/10 of those in conventional coal-fired power plants, and 1/2–1/3 of them respectively. The current trend is to increase project scale in order to further improve power generation efficiency, reduce initial investment, and enhance the reliability and utilization rate of commercial operations. Research on IGCC in China began in the early 1980s, and in the 1990s pre-feasibility studies for IGCC power plant projects were carried out, with technical and economic analyses conducted on the main processes. “During the Ninth Five-Year Plan period, key technological research was carried out in areas such as processes, coal gasification, and hot gas purification. Currently, preliminary work is underway in Yantai, Shandong, to build a 400MW-class IGCC demonstration power plant through investment. 　　1. 5 Co-generation technology systems Co-generation is a technical approach that combines energy conversion with the synthesis of chemical products, introduced in recent years. Its aim is to achieve low or zero emissions of pollutants, as well as the comprehensive utilization of resources and efficient use of energy. ? The Vision21 energy system proposed by the U.S. Department of Energy takes into account the needs of emerging development trends; it is centered around gasification, with the gas being used to produce hydrogen, which in turn is used to generate power in high-temperature fuel cells. The waste heat from these cells is utilized for heating, while CO2 and other pollutants are separated and treated during the preparation of raw materials (fuels). Shell’s concept of a syngas park is centered on coal gasification, combining chemical production with combined-cycle power generation, while also producing household gas and heat. The broader concept of cogeneration also integrates coal chemical processing, synthetic processes, and metallurgical reduction processes into a unified whole; it involves the conversion of energy into chemical products in coal mining areas, and it combines the transmission of electricity or heat into a single integrated system. 　　In cogeneration systems, systems that were previously produced separately can be simplified as a result of recombination, the requirements for raw materials are reduced, overall efficiency is increased through the complementarity of different processes, and ultimately the cost of products is lowered. ? In China’s domestic scientific and technological community as well as in the industrial sector, there is significant interest in the development of cogeneration technology, and systematic research as well as research and development on related individual technologies have been carried out. ?? 2 Requirements and Characteristics of the Development of the Coal Chemical Industry Many researchers believe that the world has entered an era of diversification in energy sources and chemical raw materials; different countries or regions should select practical and high-quality raw materials and technologies based on their resource availability and economic development needs. The technologies for producing chemicals from coal and for converting it into efficient and clean energy sources such as electricity and fuel oil are set to compete on an equal footing with petroleum and natural gas-based chemical industries. Backed by various mature individual technologies, the coal chemical industry faces new opportunities for development. ? The development of China’s coal chemical industry will be based on leveraging its resource advantages, with the aim of optimizing the energy structure – particularly the final energy consumption pattern. Through clean and efficient methods, it will provide high-quality energy support for national economic development and social progress. Its future development will feature the following main characteristics. ? (1) In addition to developing traditional coal chemical industries based on product production (coke-making, synthetic ammonia), a market-oriented approach will be adopted to develop coal chemical industries focused on energy conversion. Comprehensive coal chemical plants that combine energy conversion with co-product production will be established, such as those for coal liquefaction, gasification to produce synthetic fuels and chemical products, or for the simultaneous generation of electricity and heat. 　　(2) Larger scale, adoption of advanced technology. Against the backdrop of global economic integration, it is necessary to foster world-class large-scale coal chemical enterprises and establish large-scale factories with international competitiveness, such as coal chemical plants capable of producing products in the millions of tons per year. By utilizing advanced domestic and international technologies and modern equipment, clean production is achieved and clean products are provided, such as modern liquefaction processes and advanced synthetic reaction technologies. ? (3) In the development of the new coal chemical industry, enterprises will become the main drivers of new technology development. Companies invest in the development of advanced technologies for technological upgrading and progress, while focusing on the commercialization of these new technologies in domestic and international markets. ? (4) It facilitates the structural adjustment of the coal industry and promotes technological collaboration among related sectors, thereby stimulating domestic demand and creating conditions for employment; the coal chemical industry, equipped with advanced technologies, will be given priority in development. ? 3 Opportunities and Development Trends of the Coal Chemical Industry With the development of the market economy and global economic integration, China’s coal industry, particularly large-scale coal enterprises, is continuously adjusting its industrial and product structures, and developing the coal chemical industry represents one of the most important approaches for this purpose. 3.1 Coal liquefaction will become an important direction for the new coal chemical industry. The scarcity of oil resources and insufficient domestic oil supply have become serious challenges in China’s energy development. Based on the quality of coal and other comprehensive factors, the development of direct and indirect coal liquefaction has become a focus of attention for domestic coal enterprises and coal-producing regions. ? As a high-tech method for the chemical conversion of coal, the industrialization of coal liquefaction will require a lengthy period of development. Issues that need to be addressed include: ① Studying the technical development plan for coal liquefaction as well as the future industrial structure, taking into account factors such as resources and economics ； ②By integrating advanced technologies, improving and upgrading the overall industrial technology and equipment, engineering demonstrations will be completed in the near future, while processes and key equipment with independent intellectual property rights will also be developed ； ③Improve the investment and financing mechanisms for the construction of commercial factories, and broaden domestic and international investment and financing channels ； ④Research and develop policy frameworks for the development of coal liquefaction ； ⑤Funded jointly by **, enterprises, research institutions, etc., a **-level research and engineering technology development base for coal liquefaction will be established to train specialized teams. ? The industrial development of coal liquefaction in our country is expected to see 1–2 commercial demonstration projects based on imported technologies by 2005; the practical application of domestically developed technologies is expected to be fully realized by 2010, after which a new industry based on the high-tech conversion of coal will gradually take shape. ? 3.2 Coal gasification plays an important role in the coal chemical industry. Developing advanced coal gasification technologies is of great significance for the development of coal chemicals within the coal industry. At present, **the relevant departments are developing gasification technologies with independent intellectual property rights, such as multi-nozzle water-coal slurry gasification and dry coal powder fluidized bed gasification; projects to introduce foreign technologies are also underway. For coal enterprises to develop gasification technologies, it is necessary to build on advanced technologies available both domestically and internationally, take into account the characteristics of different coal types and qualities, and through technical and economic analyses, develop or adopt suitable processes and furnace types, such as pressurized fixed-bed gasification and liquid slag discharge gasification. ? In the past, the development of coal gasification technology has been driven primarily by the chemical industry; the coal industry has been weak in terms of research and development, project implementation, and human resources, and it is necessary to accelerate the improvement of its overall capabilities. ? 3.3 Coal Coking: The decline of the developed coking industry, along with China’s decision to eliminate low-quality coke and phase out outdated small-scale coking processes, has created new opportunities for the development of advanced, large-scale coking industries. It is estimated that by 2005, there will be a shortage of 20 million tons per year in China’s production of machine-made coke; high-quality coke with low ash and sulfur content holds great potential for growth in both domestic and international markets. The coal industry boasts advantages in terms of raw materials and transportation; in particular, enterprises or coal-producing regions that possess high-quality coking coal resources, such as those in Shanxi and Qitaihe in Heilongjiang, have the conditions to develop large-scale production of high-quality or specialty metallurgical coke and foundry coke. They can take advantage of the current opportunities to promote the development of the coking industry from a high starting point and at a high standard. ? 3.4 Planned development of other coal chemical technologies: At present, there is strong momentum in China for developing gasification processes to produce chemical products or as alternatives to liquid fuels, such as synthetic methanol or the further processing of downstream products (acetic acid, acetic anhydride, etc.), as well as the synthesis of dimethyl ether (a one-step method for synthesizing dimethyl ether is currently under development). For coal enterprises, developing gasification synthesis offers advantages such as lower prices for the raw coal and the capability to achieve large-scale industrialization. However, it is also necessary to pay close attention to factors such as domestic and international market demand, the social benefits associated with product applications, the level of maturity of the relevant unit technologies, and competitiveness compared to petroleum and natural gas-based chemical industries. The product targets should focus on addressing shortages in the domestic market and replacing imported products. ?　Cogeneration is a coal chemical-energy system that integrates the production of various energy and chemical products, combines multiple unit processes, and optimizes technical, economic, and environmental aspects. It features flexible system configurations, and as a conceptual system relevant to future development, it requires extensive basic research as well as the development of various unit technologies. The coal industry should develop cogeneration systems. In terms of raw materials, a combination of coal, coalbed methane, and associated minerals can be considered; in terms of processes, coal chemical processing, power generation, building materials production, and metallurgy can be integrated. As for products, related outputs such as chemicals, liquid fuels, electricity, heat, gas, building materials, and metal materials should be produced, thereby achieving full utilization and recycling of resources and energy, as well as optimizing the environment and maximizing economic benefits.