"Analysis of the Development Direction and Pathways for Low-Rank Coal Pyrolysis in China during the 13th Five-Year Plan Period

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"Analysis of the Development Direction and Pathways for the Pyrolysis of Low-Rank Coal in China during the 13th Five-Year Plan Period. Author/Source: Former Chief Engineer of China National Chemical Engineering Group Corporation. Date: May 28, 2018. Clicks: 45. Former Chief Engineer of China National Chemical Engineering Group Corporation. **The Demonstration Plan for the Deep Processing of Coal during the 13th Five-Year Plan Period states: “The industry involved in processing and converting coal into various clean fuels and basic chemical raw materials, using coal as the main raw material; this includes areas such as coal-to-oil conversion, coal-to-natural gas conversion, selective utilization of low-rank coal, coal-based chemical production, and the co-production of multiple products.” It outlines the direction for the differentiated utilization of low-grade coal. Developing the coal deep-processing industry to an appropriate extent is not only necessary for building strategic technical and capacity reserves in the energy sector, but it is also an important measure to promote the clean and efficient use of coal and ensure energy security. By focusing on the pyrolysis of low-grade coal as a key approach, pursuing differentiated utilization based on different grades, emphasizing environmental protection, energy efficiency, and a circular economy, and aiming for the development of oil, gas, electricity, chemicals, and heat, it is possible to achieve significant breakthroughs in the technological development of low-grade coal in China during the 13th Five-Year Plan period. Overview: The \"13th Five-Year Plan for the Demonstration of Advanced Coal Processing Industries,\" formulated in accordance with the \"13th Five-Year Plan for National Economic and Social Development\" as well as the \"13th Five-Year Plan for Energy Development,\" was released in March this year. This plan covers important aspects such as the guiding principles, basic rules, development goals, key tasks, and safeguard measures for the demonstration of advanced coal processing industries. Urgent Issues to Be Solved A thorough analysis was conducted of the various problems existing in the emerging industry of coal deep processing during the 12th Five-Year Plan period; it was concluded that this industry is still in its initial stage, and there are several major issues that need to be addressed urgently. The production processes and environmental protection technologies need to be improved. Due to issues such as design and equipment reliability, long-term, full-load operation has not been achieved. The system optimization and integration are insufficient; there is a lack of compatibility between the main chemical processing units and the environmental protection facilities, as well as among different chemical processing units themselves. This leads to increased investment and resource consumption, thereby affecting the overall operational efficiency. The development of related environmental protection technologies is relatively lagging, making wastewater treatment difficult and costly. The construction order of demonstration projects needs to be standardized; issues such as approving projects on a larger scale than actual requirements, delays in progress, and project costs exceeding the estimated budget exist. The preliminary work already underway faces certain difficulties in securing supporting conditions such as coal resources, water rights, and emission allowances. The level of enterprise operational management needs to be improved. Most of the entities responsible for these demonstration projects come from sectors such as coal, power, and traditional chemicals; they lack in-depth research on the technology-intensive and complex field of coal deep processing, and thus have limited experience in construction and operational management. They also do not fully understand the market dynamics of oil, gas, and petrochemical products. As a result, the actual outcomes of these demonstrations fall short of expectations, and the overall level of risk control requires improvement. The industrial support system needs to be improved; progress in advancing large-scale project construction and building up the support systems is relatively slow. Design concepts and systems that suit the characteristics of the deep processing industry for coal need to be established. The standardization, normalization, and serialization of technical equipment require improvement. Standards and regulations related to engineering design, construction, products, safety, and environmental protection need to be developed and revised more promptly in order to support the healthy development of this industry. Principles to be adhered to in the development of coal chemical industry: Based on an analysis of various issues, 48-word principles for the development of coal chemistry were proposed. Independent innovation, upgraded demonstration. Strengthen original innovation, integrated innovation, and innovation through the introduction, digestion, absorption, and further development, and promote comprehensive upgrades and demonstrations in areas such as new processes, new technologies, new products, key equipment, and environmental protection. Proceed with caution, pursue green development. Adhere to the \"three red lines\" in water resources management, give equal emphasis to planning environmental impact assessments and environmental impact assessments for construction projects, implement the strictest environmental protection standards, and strive to achieve green development. Strictly control production capacity and advance in an orderly manner. Adhering to high starting points and high standards in development, the projects included in the plan should undertake clear demonstration roles; as each project matures, it should be implemented, thereby gradually raising the level and quality of the industry. Plan scientifically and pursue intensive development. Implement the National Main Functional Area Plan, and determine the industrial layout in a scientific and rational manner in accordance with the principle of \"being close to raw materials, close to markets, and located within industrial parks\". Shift the driving force to accelerate transformation. Strive to develop the deep processing industry of coal into a new driving force for the economic development of regions rich in coal resources. Accelerate the adjustment of the local industrial structure and economic transformation and development. Complementing strengths and achieving coordinated development. By making the deep processing of coal an important source for diversifying the supply of oil products, natural gas, and petrochemical feedstocks in our country, and by leveraging its synergy with traditional oil processing, we can foster a development pattern in which the oil refining, petrochemical, and natural gas industries complement each other and develop in coordination. Demonstration projects and key aspects for the differentiated utilization of low-grade coal during the 13th Five-Year Plan period: The focus of differentiated utilization of low-grade coal during this period is to make use of coal that was formed at a later stage, has a high volatile matter content, and high reactivity. By producing oil products, natural gas, chemicals, and electricity simultaneously, it is possible to maximize both the utility value and economic value of coal. This thus provides a clear definition for the application of low-rank coal. Contents of the demonstration project: For low-rank coal, efforts should be focused on developing clean and efficient pyrolysis technologies for such coal; engineering challenges related to the pyrolysis of pulverized coal and the separation of gases, liquids, and solids need to be overcome, with industrial demonstrations on a scale of millions of tons to be carried out. Research on next-generation technologies for higher oil yields, such as rapid pyrolysis, catalytic (activated) pyrolysis, pressurized pyrolysis, and hydrothermal pyrolysis. Strengthen the organic integration of pyrolysis with gasification and combustion, develop integrated pyrolysis-gasification technologies as well as integrated pyrolysis-combustion technologies, and carry out demonstration projects for the co-production of tar and electricity in conjunction with medium- and low-calorific-value gas turbines or coal-fired boilers that have been adapted for this purpose. Develop separation and conversion technologies to produce aromatics from the light components of coal tar, high-quality aviation kerosene and diesel from the medium components, and special oils from the heavy components, and carry out industrial demonstrations on a million-ton scale. The study focuses on technologies for extracting fine chemical products such as phenols, pyridines, and carbazoles from low- and medium-temperature coal tar – products that are difficult to produce using petroleum. Carry out an industrial demonstration for the hydrogenation of the full fraction of 500,000-tonnage medium- and low-temperature coal tar to produce aromatics and naphthenic oils. Carry out industrial trials, demonstrations, and promotion of semi-coke utilization in domestic stoves, industrial furnaces, sintering, blast furnace injection, large-scale fluidized bed and fixed-bed gasification, coal powder boilers, and circulating fluidized bed boilers. Building on individual technological advancements, system optimization and integration are enhanced to carry out industrial demonstrations for the selective utilization of low-grade coal at a scale of tens of millions of tons for combined production of oil, gas, chemicals, and electricity. “The new demonstration projects for the differentiated utilization of low-grade coal during the 13th Five-Year Plan period are: the Jingneng Ximeng, Shaanxi Coal Chemical Yulin, Yanchang Petroleum Yulin, Shaanxi Longcheng, and Hulunbuir Shengshan demonstration projects for the differentiated utilization of low-grade coal, each tasked with carrying out corresponding demonstration activities. See Table 1 for details. http://img.yf116.cn/image/img/20180528/1511165467681.jpg Reserve projects: The main reserve projects include: the co-production of oil and alcohol from coal in Yuheng by Yanqing Petroleum, the multi-product production through the differentiated utilization of low-grade coal in northern Shanxi by Yangquan Coal Group, the comprehensive utilization of coal at different grades in Hami by Jingneng, the differentiated utilization of coal in Tacheng by Xinjiang Chang’an Energy Chemicals, the multi-product production through the co-gasification of coal and biomass in Shuangyashan by Huaben, and the differentiated and graded utilization of low-grade coal by Hunchun Mining. Analysis of the Current Status of Low-Rank Coal Pyrolysis Technologies; Types of Pyrolysis Technologies. There are dozens of technologies for upgrading low-rank coal through pyrolysis in China. Due to the large reserves of bituminous coal and lignite, as well as their characteristics of high moisture content, high volatile matter, and flammability, it is not entirely reasonable to use low-rank coal directly. Given the complex composition of low-rank coal, there are numerous pyrolysis pathways, which results in a wide variety of processing techniques in China. Table 2 lists 22 of the more common pyrolysis technology types currently used in China. http://img.yf116.cn/image/img/20180528/151255472595.jpg http://img.yf116.cn/image/img/20180528/1512455476597.jpg http://img.yf116.cn/image/img/20180528/1513335481399.jpg http://img.yf116.cn/image/img/20180528/1514235486345.jpg http://img.yf116.cn/image/img/20180528/1515235492396.jpg http://img.yf116.cn/image/img/20180528/151655496595.jpg Key characteristics of pyrolysis technology As can be seen from Table 2, most of these low-rank coal pyrolysis processes are already in operation. Typical internal-heating vertical three-stage furnaces (for drying, carbonization, and cooling) are widely used in the production of semi-coke, among other applications. The capacity of each such plant is generally around 50,000 to 100,000 tons per year; there are also some processes that are still undergoing industrial testing. The current status of these pyrolysis technologies can be summarized in two sentences: First, most of them have passed the technical evaluations conducted by relevant authorities; technical assessments have been carried out on these devices for low-rank coal pyrolysis, and the production demonstration units have reached an advanced level in China (or the world). They possess complete independent intellectual property rights, and all design parameters meet the specified requirements. After 72 hours of operation, pyrolysis products were produced, with the tar, gas, and semi-coke meeting the required quality standards ； Secondly, it is a common phenomenon that some devices operating on a continuous or intermittent basis (with the exception of coking and carbon black production) have poor long-term stability in production; they operate on a small scale with short industrial chains, and lack complete environmental protection facilities. An analysis and summary of the above technologies are shown in Table 3. http://img.yf116.cn/image/img/20180528/151710550309.jpg http://img.yf116.cn/image/img/20180528/1517585507874.jpg Analysis of the characteristics of pyrolysis technology; the parameters related to the characteristics of 10 different pyrolysis processes in China are listed in Table 4. http://img.yf116.cn/image/img/20180528/1518575513793.jpg http://img.yf116.cn/image/img/20180528/1519355517525.jpg The typical process flow for the pyrolysis of low-rank coal with small particles, using endothermic three-stage vertical furnaces as shown in Table 4 – such as the RNZL furnace developed by Sinosteel Anshan Research Institute and the SJ furnace from Shenmu Sanjiang – is illustrated in Figure 1. http://img.yf116.cn/image/img/20180528/1520225522223.jpg http://img.yf116.cn/image/img/20180528/152059552594.jpg http://img.yf116.cn/image/img/20180528/1521405530092.jpg The typical process flow for coal powder pyrolysis using an endothermic semi-coke heat carrier moving bed, as well as the DG furnace developed by Dalian University of Technology, are shown in Figure 2, based on the information provided in Table 5. http://img.yf116.cn/image/img/20180528/1522305535019.jpg Based on the internal-heating high-temperature furnace with ash heat carrier fluidized bed shown in Table 5, as well as the ZDL furnace developed by Zhejiang University, the typical process flow for coal pyrolysis is illustrated in Figure 3. http://img.yf116.cn/image/img/20180528/1523245540470.jpg http://img.yf116.cn/image/img/20180528/152455544542.jpg http://img.yf116.cn/image/img/20180528/152449554891.jpg http://img.yf116.cn/image/img/20180528/152528555283.jpg http://img.yf116.cn/image/img/20180528/152655556591.jpg Based on the rotary kiln pyrolyzers etc. provided in Table 6, a typical process flow is shown in Figure 4. http://img.yf116.cn/image/img/20180528/152755562543.jpg http://img.yf116.cn/image/img/20180528/1527495566963.jpg Analysis of the main problems in pyrolysis. Regarding some of the low-rank coal pyrolysis technologies shown in Table 6, there are still certain issues in their practical application: Long-term stability analysis. The lanthanum carbon pyrolysis process requires coal of specific quality; lump coal must be used, and the quality of the gas produced is poor. Although the gas production volume is high, its calorific value ranges from 7.5 to 8.5 MJ/m3. The tar yield is low, the scale of operation is small, and the environmental performance is poor, with insufficient opportunities for comprehensive utilization ； The three-stage Ruchi furnace pyrolysis process uses lump coal; the quality of the gas produced is poor. Although the gas production volume is high, its calorific value ranges from 7.3 to 8.1 MJ/m3. The tar yield is low, the scale of operation is small, and the environmental performance is poor, with shortcomings in comprehensive utilization ； The LCC low-temperature pyrolysis process has certain requirements regarding particle size; the quality of the gas produced is poor. Although the gas production volume is high, its calorific value is low, and self-heating balance is insufficient, requiring an external heat source. The by-produced gas cannot be further processed, the tar yield is high, the scale of operation is small, and comprehensive utilization is inadequate ； The DG low-temperature pyrolysis process requires a certain particle size