In the battle of air pollution prevention and control, the nation has set off an upsurge of "ultra-low emissions" reform. After the initial controversy, a series of policies came into effect and ultra-low emission reconstruction projects followed. However, at present, there are still some problems in our ultra-low emission technology. In the future, it will be crucial to tackle the technical difficulties of low-load denitrification and zero-emission of desulfurization wastewater. To overcome the key technical problems to promote the transformation of ultra-low emissions Over the past six years since the concept of "ultra-low emissions" has been put forward since 2011, it has been two years since the implementation of "ultra-low-emission" in coal-fired power plants nationwide. This paper analyzes the emergence, development, The problems faced are sorted out. 1 The origin of the concept of "ultra-low emissions" The concept of "ultra-low emissions" was first proposed by Zhejiang Energy Group in 2011. The following year, Zhejiang Energy Group began to conduct extensive research on domestic and foreign advanced technology of coal-fired units pollution control. For the definition of ultra-low emissions of air pollutants in coal-fired power plant, there are many similar expressions at first, such as "near zero emissions", "ultra-clean emissions", "ultra-clean emissions" and other insiders believe that coal- The level of "ultra-clean", "near zero" state more difficult than the current engineering level, "ultra-low emissions," the concept of emission standards from the point of view to define the concept of more reasonable. At the China Electric Power Development Forum 2015, Liu Zhitan, director of the Institute of Gas Turbine Research, State Electricity Science Research Institute, concluded after a large number of comparative analyzes and data analyzes: "To seek truth from facts and to name it scientificly," zero-emission "and" ultra-clean emission " And the concept of "emission of gas turbines" are not rigorous and unscientific, we suggest the concept of "ultra-low emission". 2 "Ultra Low Emissions" initial controversy As soon as the concept of "ultra-low emissions" was proposed, there was a rapid and widespread controversy in the power industry. Questioning one side, Wang Zhixuan, Secretary-General of the CEC, once mentioned in his article "Unscientific Near Zero Emission of Coal-to-Electricity": (1) The concept of "near zero emission" is unclear, and is generally based on "emission standards of gas turbines" According to the report, there is an absurd result of the misunderstanding of the surface emission of emission standards. (2) Continuous monitoring of flue gas technology is difficult to support the accuracy of "near zero emission" monitoring data. It is a conceptual mistake to directly compare the monitoring data of daily average concentration or multi-day average concentration with the emission limit value. It is difficult to prove that the running time is insufficient "Near Zero Emissions" System Stability. (3) "Near Zero Emission" is technically not major innovation, and the harsh conditions are not generally achieved by coal-fired power plants. (4) The input-output ratio of "near zero emission" of environmental benefits and economic benefits is too low. Supporting one party, Jiang Hao, executive vice president of Beijing Guoneng Zhongdian Energy Saving and Environmental Protection Technology Co., Ltd., believes that near zero emission is the only way to solve the structural contradictions of energy. Jiang Hao believes that near zero emissions is the best solution to haze pollution in the eastern region. Near-zero emissions can make coal-fired power plant emissions comparable to gas power generation, and even better than gas power generation, which can completely break the environmental bottlenecks of coal-fired power plants. Achieving the emission standards of coal-fired thermal power plants to meet the emission standards of gas turbines can well solve the various shortcomings of the transfer of energy sources to the west and greatly increase the energy efficiency of the whole society. 3 A series of "ultra low emissions" projects Despite the constant questioning of "ultra-low emissions", ultra-low-emission retrofit projects have been carried out one after another. The first set of ultra-low-emission flue gas devices was put into operation at Unit 8 of Zhejiang Energy Conservation Power Generation Co., Ltd. at 13:45 on May 30, July 16, 2014, Jiangsu Province, the first coal-set "ultra-low-emission" environmental transformation unit in the State Power Jiangyin Sulong Thermo Power Co., Ltd. formally put into operation. July 21, 2014, Zhejiang Jiaxing Power Plant two million kilowatts of coal-fired units ultra-low emission technology renovation project through the national authority testing. On September 17, 2014, Unit 2 of Zheneng Liuheng Power Plant successfully passed 168 hours of continuous full-load trial operation and formally handed over production. On September 11, 2014, Huaneng Zibo Baiyanghe Power Generation Co., Ltd. Unit 6 total exhaust gas emissions through the Shandong Provincial Environmental Monitoring Center Station monitoring, the data completely meet the ultra-low emission standards. In September 2014, the project of environmental protection "ultra-low emission" for China Huadian Corporation's Hebei Huadian Shijiazhuang Yuhua Thermal Power Co., Ltd. Unit 1 was completed and put into operation smoothly. 4 The introduction of central policies and incentives In March 2015, the "Report on the Work of the Government" of the Third Session of the 12th National People's Congress explicitly requested "to promote ultra-low emission retrofit of coal-fired power plants." In December 2015, the State Council executive meeting decided that coal-fired power plants should be fully implemented by 2020 Ultra-low emissions and energy saving. So far the indicators of ultra-low emissions have also been further clear. Aiming at the emission of nitrogen oxides (NOx), sulfur dioxide (SO2) and soot (PM) in coal-fired flue gas, the requirement of "50355" was put forward that under the condition of 6% 50mg / Nm3, SO2 <35mg / Nm3, PM <5mg / Nm3. December 9, 2015, the National Development and Reform Commission, Ministry of Environmental Protection, the National Energy Board jointly issued by the three departments, "on the implementation of ultra-low-emission coal-fired power plant price support policy issues related notice" will be from January 2016 1 Day on the completion of ultra-low emissions coal-fired power generation companies to give subsidies to feed-in tariffs. On January 1, 2016 has been combined operation of the existing unit, its purchase of electricity on the net increase of 1 cent per kilowatt-hour (including tax); on January 1, 2016 after the grid and run the new unit, its Unified purchase of electricity increases 0.5 cents per kWh (tax included). The above tariff increase tentatively implemented by the end of 2017, after 2018 gradually unify and reduce the standard. 5 The major power generation groups to fully implement ultra-low emissions With the help of the electricity price subsidy policy, the major power generation groups responded positively to the national requirements promptly and comprehensively carried out the transformation of ultra-low emissions. As of January 2016, nearly 200 million kilowatts of coal-fired units across the country have completed technological transformation of ultra-low emissions, coal-fired power units undergoing technical transformation, more than 80 million kilowatts. Coal-fired power units are all accelerating to the era of ultra-low emissions. Shenhua Group in the country already has more than 50 units of coal-fired units to achieve ultra-low emissions, by the end of 2020, Shenhua 300MW class or above coal-fired generators will also be fully achieved "ultra-low emissions." As of the end of 2015, Datang Group's ultra-low emission units reached 65 units, accounting for 25.2% of the capacity of coal-fired power generating units, with the highest proportion in the five major power generation groups. In 2016, Datang Group plans to complete the transformation of ultra-low emissions of 84 units with a total investment of 5 billion yuan. In 2015, the performance of sulfur dioxide, nitrogen oxides and soot emissions of Huaneng Group decreased by 71% over 2010 respectively,