[High-End Interview] What is the significance of coal catalytic gasification technology?

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This post was last edited by liaifeng on 2018-9-3 at 18:19. [Exclusive Interview] What is the significance of coal catalytic gasification technology? Original article published on 2016-09-21 by China Coal Chemical Industry, Coal Chemical Industry Network. An interview with Bi Jicheng, a leading expert in coal catalytic gasification in China and deputy director of the Key Laboratory of Coal-Based Low-Carbon Energy at SNOW Group. By Chen Jijun. Bi Jicheng is an expert in fluidized bed gasification, a pioneer in coal catalytic gasification technology in China, a researcher at the Key Laboratory of Coal Conversion at the Shanxi Institute of Coal Chemistry, Chinese Academy of Sciences, and a doctoral supervisor. He is also an expert in the interdisciplinary scientific fields covered by the Ministry of Science and Technology’s 973 Program. As deputy director of the Key Laboratory of Coal-Based Low-Carbon Energy at Hebei SNOW Group, he is considered a leading scientist in coal gasification. He has long been dedicated to research on cutting-edge technologies such as co-gasification/co-pyrolysis of coal and biomass, coal catalytic gasification, coal hydrogenation gasification, coal catalytic hydrogenation gasification, and coal supercritical water gasification. He has successfully developed a series of technologies for the continuous conversion and utilization of carbon-containing organic materials (coal, biomass, waste plastics, waste tires, etc.) under supercritical water conditions, and he was the first to develop a technique for the continuous treatment of coking wastewater using supercritical water oxidation. Among the five major modern coal chemical pathways, coal-to-natural gas is in the most awkward position. On the one hand, the decline in international oil and gas prices along with lower domestic natural gas prices have eliminated the cost advantages that coal-to-natural gas once had. On the other hand, in order to obtain as much methane as possible from the gasified material, most of the coal-to-natural gas projects that have been built or are under construction in the country use the Ruhr process, a two-step method for methane synthesis. This process generates large amounts of organic wastewater containing phenols, polycyclic aromatic hydrocarbons, and other substances that are difficult to treat. This not only increases the investment in environmental protection facilities and the operating costs of these projects, but it also prevents them from functioning properly due to the difficulty in meeting wastewater discharge standards, resulting in low profitability. Under such circumstances, there is an urgent need for an advanced coal gasification technology – coal catalytic gasification – that features high coal conversion efficiency, a high methane content in the gasified product, and low amounts of wastewater that are easy to treat. Is such a technology available? Yes. Dr. Bi Jicheng, a leading expert in coal catalytic gasification in our country and deputy director of the **Key Laboratory for Coal-based Low-carbon Energy at Hebei XinAo Group, can provide us with a detailed explanation of the history and development of coal catalytic gasification technology. Developed by multiple countries, completed in China. Reporter: Please introduce the basic aspects of coal catalytic gasification technology. Bi Jicheng: The full name of coal catalytic gasification is the technology for producing methane through coal catalytic gasification. At its core, it involves the gasification, conversion, and methanation of coal under relatively mild conditions in a pressurized fluidized-bed gasifier, using alkali/metalloid catalysts to produce methane products. The greatest advantage of this technology is that it combines the endothermic coal gasification reaction with the exothermic water-gas shift and methanation reactions; without the need for a desulfurization process, coal can be converted into methane, hydrogen, and carbon monoxide in a single reactor. Among them, the methane content in the syngas at the outlet of the gasifier is about 20%, which is nearly twice as high as that in methane production using existing fixed-bed gasification technologies. Therefore, the coal catalytic gasification for methane production technology can also be considered one of the gasification technologies specifically designed for coal-to-natural gas production. Reporter: Which country was the first to **develop** coal catalytic gasification technology? Bi Jicheng: The concept of coal catalytic gasification existed as early as the 1920s. However, due to various factors, it remained at the laboratory research stage for a long time. After the oil crisis erupted in the 1970s, Europe and the United States, which suffered from oil shortages, began to pay attention to and support research on this technology. Among them, the U.S. Department of Energy commissioned ExxonMobil of the United States to carry out a series of research and development efforts, constructing a development facility for the electric heating process with a capacity of 1 ton per day, and conducting experimental development for over 5 years. But with the end of the oil crisis, research and development on coal catalytic gasification technology came to a near halt worldwide. Entering the 21st century, as the scale of oil refining expanded, the production of petroleum coke continued to increase significantly. How to convert the large quantities of petroleum coke, which pose a challenge for refining companies, into the clean energy source methane has become a focus of attention for major energy giants. In 2004, the American company Megapower Energy built another development facility for an electric heating process with a capacity of 1 ton per day, building on the research conducted by ExxonMobil. It continued to work on and study catalytic gasification technology, and ultimately developed a coal catalytic gasification technique that uses potassium, sodium, and lithium salts as catalysts, high-temperature and high-pressure steam as a heat source, and petroleum coke as the main material to be processed. Due to the difficulty of achieving economic viability in industrial production for the high-pressure and high-temperature steam required by this technology – 4.0 megapascals and 850 degrees Celsius – coupled with a low gasification temperature, long residence time of the reactants, and the need for an expensive lithium catalyst, it is difficult to scale up the gasification furnaces, and their economic feasibility is in question; as a result, this technology has not yet been put into industrial use. Reporter: When did China begin research on coal catalytic gasification technology? What are the characteristics of Chinese technology? Bi Jicheng: China’s research on coal catalytic gasification technology progressed almost in parallel with that of U.S. company Gigapower. Since the 21st century, SNCC Group has decided to develop coal catalytic gasification for methane production, in order to find technical support for future coal-to-natural gas projects. In 2009, building on previous research and development efforts, SNOW Group formed a R&D team together with the Shanxi Coal Chemistry Research Institute of the Chinese Academy of Sciences. They applied for **science and technology support projects and 973 projects from the Ministry of Science and Technology, in order to work together on developing the technology for catalytic gasification of coal using pressurized fluidized beds to produce natural gas. After carefully analyzing and summarizing domestic and international research achievements, the research team proposed a new concept for partial oxidation/catalytic gasification of coal, designed a new type of staged gasification furnace, and developed a new technology for producing methane through coal catalytic gasification that integrates coal pyrolysis, catalytic gasification, and combustion. The gasifier of the new technology consists of three parts: upper, middle, and lower. The upper end is the pyrolysis unit, the middle part is the catalytic gasification unit, and the lower end is the combustion unit. The entire material flow is as follows: semi-coke from the upper pyrolysis unit + oxygen → catalytic gasification → high-temperature raw gas + residual carbon ； High-temperature raw gas → upper-end pyrolysis unit (heat exchange through counterflow contact with the fed coal) → low-temperature coal pyrolysis → raw gas containing about 20% methane + coal tar + semi-coke → oil and gas separation → gas → methanation unit → synthetic natural gas ； Tar → Further processing to produce fine chemicals ； Unvaporized residual carbon and inert materials → combustion chamber at the lower end of the gasification furnace (+ oxygen) → partial oxidation/gasification (combustion) → provides heat for catalytic gasification. In July 2013, the development unit for the 5 tons/day pressurized fluidized bed gasification process achieved stable operation for 106 hours after feeding coal under conditions of a pressure of 3.5 MPa and a temperature of 750 degrees Celsius; the carbon conversion rate was 95%, the methane content in the exhaust gas was 22%, and the catalyst recovery rate was 98%. This achievement was evaluated by industry experts including Cao Xianghong, an academician of the Chinese Academy of Engineering, as being “at the international leading level”. Thus, China has achieved success in the development of coal catalytic gasification coupling technology, a project that took nearly 5 years. Reporter: Has this technology already been put into use? Bi Jicheng: Following the success of the process development unit, CNPC Group and Saiding Engineering Co., Ltd. collaborated to develop the process package for an industrial demonstration project. Currently, an industrial demonstration unit with a coal processing capacity of 1,500 tons per day and a natural gas processing capacity of 200 million cubic meters per year is being built in the Xinneng Chemical Industry Park in Dalat Banner, Inner Mongolia. As planned, the demonstration unit is set to begin trial operation in 2018. Upon completion, it will become the world’s largest industrial demonstration facility for coal catalytic gasification to produce methane, with fully independent intellectual property rights in China. It offers multiple performance advantages over the “two-step” method. Reporter: What are the advantages of coal catalytic gasification for methane production compared to the current coal gasification methanation technology? Bi Jicheng: The current technology for producing methane from coal gasification involves first gasifying coal under high temperature and pressure to obtain hydrogen and carbon monoxide, and then synthesizing methane; this is commonly known as the two-step method. The representative technology is the Lurgi fixed-bed gasifier, with a methane content in the outlet gas of about 10%. Due to the need to undergo high temperatures, low temperatures, and again high temperatures, as well as conversion and deep desulfurization, the process is complex, requires significant investment, and has high energy consumption. Furthermore, since only lump coal can be used as raw material, the cost is high, resulting in poor economic viability for the project. Compared with the two-step method, coal catalytic gasification technology has the following advantages: first, it can use pulverized coal (less than 5 millimeters) as raw material, eliminating the need for crushing; as a result, the raw material cost is lower and the range of available materials is wider ； Secondly, the methanization process inside the furnace does not require desulfurization, and the methane content in the outlet gas is over 20%; as a result, the scale of the subsequent methanization units and the equipment investment required are significantly reduced ； Third, there are no insoluble challenges in wastewater treatment ； Fourth, the overall energy utilization efficiency is high. Reporter: Due to its low gasification temperature, the Luchi furnace tends to generate large amounts of organic wastewater containing phenols, tar, and other substances that are difficult to treat. Coal catalytic gasification takes place at lower temperatures, and it also generates wastewater containing phenols and tar. Then why do you say that there are no unsolvable wastewater treatment problems? Bi Jicheng: If direct water spraying, the same method used in the Lurgi process, is employed to cool raw gas, then coal-catalyzed gasification for methane production will inevitably generate large amounts of organic wastewater containing tar and phenols. On the one hand, we use indirect condensation technology to replace direct water spraying for cooling the outlet gas, thereby minimizing the generation of organic wastewater ； On the other hand, the organic wastewater generated without participating in the gasification reaction is introduced into the water washing section for catalyst recovery, where it dissolves the metal catalysts carried in the recovered gas. The coal is then impregnated with this wastewater, which is rich in phenols, tar, and catalysts, followed by drying of the coal. The dehydrated coal, which has absorbed phenols, tar, and catalysts, enters the pyrolysis unit at the upper part of the integrated coal catalytic gasification furnace, where it undergoes pyrolysis and gasification reactions. The small amount of wastewater containing low-boiling-point organic compounds generated during the coal drying process is sent to the biochemical wastewater treatment unit or used in the preparation of water-coal slurry, thereby completely solving the problem of treating organic wastewater encountered in the two-step process of the Lurgi furnace. By integrating the catalyst recovery process, it not only significantly reduces the difficulty of wastewater treatment but also utilizes organic substances such as tar in the wastewater for gasification, thereby improving the efficiency and economic viability of the process. Reporter: What is the catalyst used in coal catalytic gasification technology? Will the use and recycling of catalysts significantly increase production costs and cause new pollution? Bi Jicheng: At present, we use potassium carbonate as the benchmark catalyst, with an addition amount of about 10% of the coal input. Thanks to a catalyst recovery rate of up to 98%, as well as the use of wastewater and low-grade heat sources in the catalyst recovery process, the cost associated with catalyst use and catalyst recovery systems is kept below 5% of the total cost of coal-to-gas production. To further reduce these costs, we also conducted evaluation experiments on cheaper composite catalysts, and achieved good results; once they are put into use, the costs associated with the catalysts and their recovery will be reduced even further. As for whether the use of catalysts will cause new pollution problems, since water-soluble catalysts are completely recovered, and the trace amounts of catalyst remaining in the coal ash undergo very stable chemical reactions with the coal ash, no new pollution is generated. Reporter: Is there a comparison in the level of investment required for the two technologies? Bi Jicheng: The two-step process involves a long production sequence, and the methane processing unit is large in scale. Moreover, the methanation catalysts, large-scale methanation reactors, and high-temperature recycle gas compressors used in this unit all have to be imported, resulting in high costs. Furthermore, substantial capital is required to build wastewater treatment facilities (for a coal-to-gas project with a capacity of 4 billion cubic meters per year, the investment in wastewater treatment facilities alone exceeds 1 billion yuan); as a result, the investment needed for the two-step process is significantly higher than that for coal catalytic gasification technology. Saiding Engineering Co., Ltd. has calculated that, on a par scale, the investment ratio between the former and the latter is 10:7. Take the industrial demonstration project in the Xinneng Chemical Industry Park in Dalaat Banner, Inner Mongolia, which is under construction and has a coal handling capacity of 1,500 tons per day as well as a natural gas supply volume of 200 million cubic meters, as an example. If 2 billion cubic meters of industrial production is achieved, and based on a local calorific value of 4,000–5,000 kcal/kg for bituminous coal and current prices of 170–230 yuan per ton, the cost of natural gas produced through coal catalytic gasification would be around 0.92–1.06 yuan per cubic meter. This is at least 0.4 yuan per cubic meter lower than the cost in several coal-to-gas demonstration projects that have already been put into operation. There is still a long way to go in terms of industrial application. Reporter: Given the many advantages of coal catalytic gasification technology, why isn’t it being widely adopted? Bi Jicheng: The successful development of industrial coal catalytic gasification technology indicates that China now possesses an advanced new methane production technique based on coal gasification, one with independent intellectual property rights. This provides strong technical support for the development of China’s coal-to-natural gas industry; however, it does not mean that this technology will be widely adopted promptly. On the one hand, this technology has so far only been validated using process development equipment. Only after undergoing operational verification through the industrialization demonstration project under construction in Dalat Banner, Inner Mongolia, can it become a truly advanced, practical, and reliable technology, thereby laying the foundation for its widespread industrial application. The scaling up of industrial gasification furnaces is often challenging, as it requires solving not only gasification-related technical issues but also a large number of engineering problems. Unexpected difficulties arose, and there was also the need to deal with various positive and negative reactions from the industry and public opinion. On the other hand, the advantages of so-called coal catalytic gasification technology, such as low energy consumption, low investment, low costs, and favorable environmental impact, are relative to the existing two-step Lurgi process technology. However, the competitiveness of coal-to-natural gas ultimately depends on its comparison with domestically produced conventional natural gas. Objectively speaking, based on current analyses, coal catalytic gasification technology does not have very obvious advantages over conventional natural gas, but it can address the issue of natural gas shortages. Therefore, before the industrial demonstration projects are put into operation and the technology itself has been validated through operation in industrial-scale facilities, we are not in a hurry to promote its widespread application. Reporter: It is evident that you are a very pragmatic technology professional. So what is your view on the future of the coal chemical industry? Bi Jicheng: First of all, we are full of confidence and unwavering in the prospects of modern coal chemical industry. Although the slowdown in global economic growth and low oil and gas prices have had a significant impact on the coal chemical industry, forcing the still-developing modern coal chemical sector to slow down its growth, in the long term, oil and gas, as non-renewable resources, have limited reserves. Excessively low prices for oil and gas will stimulate global consumption of these resources, accelerating their depletion; as a result, after remaining low for a while, their prices will rise again, and the cost advantages of coal chemistry will become evident once more. Secondly, developing modern coal chemical industry is a strategic choice for China to take advantage of its resource profile characterized by a lack of oil and gas but an abundance of coal, as well as to ensure strategic energy security. ****Requirements have been put forward for the clean utilization of coal from five aspects, and modern coal chemical industry is recognized as one of the ways to achieve clean and efficient use of coal; all these factors ensure that China’s modern coal chemical industry will not be abandoned halfway. Thirdly, under current circumstances, the competitiveness of coal chemical projects remains unsatisfactory. Apart from the fact that coal itself has a complex structure and is difficult to process and convert, this is mainly because modern coal chemistry is still in its infancy; there are few advanced, stable, and practical process technologies available for selection. In particular, there is still no systematic integrated coupling technology. In the future, if it becomes possible to achieve co-production of coal-to-natural gas technology and coal-to-oil technology, or to develop multi-product technologies using coal, the overall efficiency of coal utilization will increase further. Therefore, to truly address the issues of high energy consumption, excessive emissions, and poor competitiveness in the coal chemical industry, we must not stay stagnant; instead, we need to face these challenges head-on, accelerate technological innovation and integrated optimization, and develop more advanced, practical, reliable, and environmentally friendly new technologies. For SNCC Group and my R&D team, during the 13th Five-Year Plan period, it is necessary to accelerate the construction of industrial demonstration projects for coal catalytic gasification, ensuring their commissioning on schedule. By carrying out construction and trial operations, we can gain experience, address shortcomings, optimize the process layout and equipment design, thereby continuously improving the energy efficiency and profitability of these facilities, and facilitating their safe and widespread adoption. On the other hand, efforts will be accelerated to develop a second generation of new catalysts that are more efficient and cost-effective, as well as new gas-flow bed coal hydrogenation gasification technologies for methane production, along with other advanced gasification techniques suitable for different types of coal in China. Ultimately, through the separate use or combination of these various advanced technologies, it is possible to achieve full utilization of coal, thereby addressing issues such as high energy consumption, high water usage, and large carbon dioxide emissions in coal chemical processing. This will enhance the competitiveness of modern coal chemical industries, including those involved in coal-to-natural gas production, and promote the healthy development of the coal chemical sector. Reporter: Thank you for the introduction! Source: Magazine \"China Coal Chemical Industry\" Subscription Phone: 010-64697978