Clean and efficient utilization of coal in China: from black to green

The resource endowment of rich coal, poor oil and little gas determines that coal will still be the most important consumption energy in China for a long time in the future. Under the background of energy transformation and upgrading in recent years, China has an urgent need for clean and efficient utilization of coal. The clean and efficient utilization of coal mainly includes two elements: improving the quality and efficiency of coal utilization and effectively reducing the emission of pollutants in the process of coal utilization. China has achieved the rapid development of clean and efficient utilization of coal by means of coal quality improvement processing, modern coal chemical industry, ultra-low emission of coal-fired power generation and other technical means. The upgrading of coal washing and upgrading technology in China mainly includes coal washing and upgrading of low rank coal. Coal processing with improved quality is an important way to realize clean and efficient utilization of coal. The guiding opinions on promoting the scientific development of coal industry issued by the state energy administration also mentioned that the development of coal industry "should adhere to the principle of improving quality, increasing efficiency and intensive development". In terms of coal washing, according to the statistics of coal industry planning and Design Institute, in 2018, China's coal mining and washing industry capacity utilization rate was 70.6%, up 3.52% year on year. In recent years, the utilization ratio of coal production capacity in China has increased significantly. In terms of coal quality improvement, the economic benefits and environmental protection benefits are not ideal in the utilization process of low rank coal. The quality can be improved by improving the calorific value, combustion characteristics and gasification technology compliance. The pyrolysis technology of low rank coal developed in China has been in the international leading level.

The pyrolysis technology of low rank coal is a process of heating the low rank coal to a certain temperature under the condition of isolation of air or non oxidation atmosphere, generating pyrolysis reaction and producing semicoke, coal tar and gas. For example, the "sm-gf" independently developed by Shaanxi coal chemical industry group and Beijing Guodian Futong science and Technology Development Co., Ltd. has been at the international leading level, and the single set processing capacity of the successfully developed segmented multi-layer vertical rectangular pyrolysis furnace has reached 500000 tons / year, realizing self dedusting and uniform distribution of gas in the furnace, effectively solving the problem At present, there are many technical problems such as industrialization of mixed coal pyrolysis, small scale of single treatment, low efficiency of oil dust gas separation and so on. It is reported that the first phase of the planned 15 million tons / year coal quality separation, clean and efficient conversion project of Shaanxi Coal Group Co., Ltd. in Yulin has been started and passed the safety facility design review in October this year. From Shaanxi Yanchang Zhongmei Yulin Energy and Chemical Co., Ltd., it was reported that by 7:00 on October 24, the annual cumulative production of polyolefin products of Yulin Energy and Chemical Co., Ltd. had reached 1.00164 million tons, successfully breaking through million tons. This year, the company developed and produced 12 brand polyolefin new products, becoming the first enterprise capable of producing terpolypropylene products outside Sinopec and PetroChina systems. In recent years, China has accelerated the transformation of coal from single fuel to both raw material and fuel. Coal chemical industry is a process in which coal is converted into gas, liquid and solid fuels and chemicals by chemical processing, which is a powerful means to realize the efficient utilization of coal resources. China's modern coal chemical technology continues to mature, breakthroughs have been made in the fields of synthetic gas conversion, large-scale coal to methanol, direct coal to oil, indirect coal to oil and other technical fields, and the demonstration project of clean and efficient coal conversion has been continuously promoted. According to the data released by Sinopec Federation, in 2018, the total capacity of coal to oil will remain unchanged at 9.53 million tons / year. The total capacity of coal (methanol) to olefin reached 13.02 million tons / year, an increase of 4.8% year on year.

In 2018, the total capacity of coal to gas remained unchanged, still 5.105 billion m3 / year. In 2018, coal to oil, coal (methanol) to olefin and coal to gas increased by 24.8%, 4.8% and 7.5% respectively year on year. The 13th five year plan of coal deep processing industry demonstration issued by the National Energy Administration in 2017 refers to the development scale goal of coal chemical industry. It is estimated that in 2020, the coal to oil production capacity will be 13 million tons / year, the coal to natural gas production capacity will be 17 billion cubic meters / year, and the low-grade coal utilization capacity will be 15 million tons / year (coal processing capacity). During the 13th five year plan, the upgrading demonstration of five types of modes and general technical equipment, including coal to oil, coal to natural gas, low-grade coal utilization by quality, coal to chemicals, coal and oil comprehensive utilization, will be focused on. The development of modern coal chemical industry in China is continuous, but there is also a shortage of high-end products and low-end overcapacity. Xing Lei, director of the research center of coal listed companies of the Central University of Finance and economics, said: "to solve this problem, we need to work in multiple ways. The first is to phase out the traditional coal chemical production capacity with heavy pollution, high energy consumption and overcapacity, and the state will no longer approve such projects. Secondly, it is to develop new coal chemical technology and equipment, and gradually realize the localization of key technology and equipment. Technological progress is the key to solve the problem of high-end and green coal chemical industry, which needs to be forced by high requirements. In addition, modern coal chemical projects have large investment and high risk, and many projects still have problems of high energy consumption, heavy pollution, especially water consumption. Therefore, we should avoid going up in a crowd and blooming everywhere. We should adhere to high standards, gradually pilot and develop cautiously. " Establish a clean and efficient coal power system to comprehensively implement the upgrading and transformation of energy conservation and emission reduction in the coal power industry and build the largest clean and efficient coal power system in the world.

The former Ministry of environmental protection, the national development and Reform Commission and the National Energy Administration issued the work plan for comprehensively implementing ultra-low emission and energy saving transformation of coal-fired power plants in December 2015, which mentioned that coal-fired units with sufficient conditions should implement ultra-low emission and energy saving transformation For low emission transformation, units that do not meet the transformation conditions shall be subject to emission control up to standard, units with backward production capacity and units that do not meet the requirements of relevant mandatory standards shall be eliminated, and energy conservation and ultra-low emission transformation shall be coordinated. As a whole, China's coal-fired power generation technology has been in the leading level in the world. According to the data released by the China Federation of electric power enterprises, by the end of 2018, China's total installed capacity of coal-fired power was 1008.35 million kilowatts, and 111 million kilowatt ultra supercritical units had been put into operation nationwide. At the same time, in 2018, the average coal consumption for power supply of thermal power units nationwide reached 307.6 g / kWh, which is significantly better than the average level of the United States and the world. The coal consumption for power supply of advanced megawatt reheat units has been less than 270 g / kWh, leading the development direction of coal-fired power generation in the world. In the field of coal-fired power generation in China, the technical achievements of ultra supercritical power generation, circulating fluidized bed combustion, IGCC and multi generation are significant. Taking CFB combustion as an example, CFB boiler is a new type of clean coal combustion technology. In recent years, China has owned 150000 kW, 200000 kW, 300000 kW and 600000 kW CFB boiler series products with independent intellectual property rights.

According to the 13th five year plan for energy development issued by the national development and Reform Commission and the national energy administration, we should optimize the planning and construction sequence, accelerate the elimination of backward production capacity, and promote the clean and efficient development of coal power. The goal of clean and efficient development of coal power is put forward. In 2020, the average coal consumption of coal power generation units will be controlled below 310 grams per kilowatt hour, among which the newly built units will be controlled below 300 grams, and the emission concentration of sulfur dioxide, nitrogen oxide and soot will not be higher than 35 mg, 50 mg and 10 mg per cubic meter respectively. In the field of coal-fired power generation, there is a lack of adaptability between the coal utilization mode and the characteristics of coal resources. In response, Ruan Lijun, Deputy Secretary General of China coal processing and Utilization Association, said: "I think coal enterprises are not only responsible for mining and production, but also for selecting and matching according to the use of customers in the future. Coal enterprises should become the production, selection and distribution center of coal. Coal, as a product, should not be a traditional commodity. In some fields, it can also be a "high-end" product, even with its own brand and packaging. For coal products to be used in different levels, according to the quality of coal sold to different users. A lot of high sulfur coal can not be mined, but in fact, it can be completely used in the field of coal chemical industry. It can not only not pollute, but also recover sulfur or make sulfur products. "