【Frontiers in HaiChuan Chemical Technology】Nanometer high-entropy ceramic coatings developed by Lanzhou Institute of Chemical Physics passed energy efficiency tests in 165MW coal-fired power units

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As China’s coal reservoir, Xinjiang accounts for 40.6% of the country’s estimated coal reserves. The reserves of high-alkali coal in the Junggar region amount to about 390 billion tons, serving as a crucial source for ensuring energy supply across the country. In the construction of new energy bases in sandy, desertous areas and in provinces such as Gansu, Xinjiang, Qinghai, Inner Mongolia, and Ningxia, as well as in the systems for transporting green electricity, advanced coal-fired power units with the capability for deep peak shaving play a crucial role in providing electrical support and regulating the system. In the field of thermal power generation, coal costs account for 70-80% of the total cost of power production, directly affecting the economic viability of power plants. Using low-cost, high-alkali coal from Zhundong has become an important strategy for ensuring profitability in peak-shaving thermal power plants and conventional coal-fired power plants. In 2024, the volume of coal exported from Xinjiang exceeded 139 million tons, with the scope of these exports gradually expanding to regions such as Central China as well as the provinces of Hubei and Hunan along with the Yangtze River region, thereby contributing to ensuring a stable supply of energy across the country. However, the high-alkali coal in Zhundong, Xinjiang, can cause problems such as boiler coking, high-temperature corrosion, tube bursts, high coal consumption, and low thermal efficiency, severely affecting the safety and economic efficiency of power plant boilers. Conventional methods such as furnace structure modifications, adjustment of combustion parameters, blending in kaolin, and thermal spraying for protection have not truly solved the industry’s challenges. In recent years, the research team led by Researcher Gao Xianghu from the Low-Carbon Energy Materials Group at the Center for Resource Chemistry and Energy Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, has been focusing on high-alkali coal from Xinjiang, and working on key technologies for protecting the radiation heating surfaces of large-scale power plant boilers as well as improving energy efficiency. The nanometer high-entropy protective and energy-saving ceramic coating developed by the team overcomes key technical challenges related to ceramic materials, such as anti-coking properties, resistance to high-temperature corrosion, infrared enhancement capabilities, high thermal conductivity, and adjustable thermal expansion coefficients. It also possesses multiple functions such as reducing coal consumption and improving compatibility with different types of coal, making it suitable for use in large-scale peak-shaving power plants as well as other conventional power plants. In 2022, this technology was applied to two 1000MW ultra-supercritical peak-shaving units in China, achieving good results. Recently, with the strong support of Huaneng Lanzhou Xigui Thermal Power Co., Ltd. and Xi’an Thermal Engineering Research Institute, the team first completed the numerical simulation for 165MW units. The results showed that the temperature distribution curve of the flue gas inside the boiler with a quadrilateral cut-circle shape followed a normal-parabolic pattern: the temperature was high in the central combustion area, while the temperature at the bottom of the boiler and at the furnace outlet was lower. The highest combustion temperatures were always found between the main combustion zone and the SOFA zone; therefore, the key areas for spraying were the main combustion zone and the SOFA zone. Subsequently, the team applied the nano-high-entropy ceramic coating to the entire furnace radiation heating surface of the 165MW unit. The energy efficiency test results conducted by Xi’an Thermal Engineering Research Institute show that, after 5 months of operation in the furnace, no significant coking or high-temperature corrosion occurred in the material. By comparing the measured data before and after spraying, under high, medium, and low loads, the effective heat absorption rate inside the furnace increased by an average of 5.19%, the amount of water used for temperature reduction decreased by 2.6 t/h, the flue gas temperature dropped by 4.5°C, the physical heat loss due to ash and slag was reduced by 0.21%, the thermal efficiency of the boiler improved by 0.46%, and the coal consumption per unit of electricity generated decreased by 1.5 g/kWh. A 1000MW coal-fired power unit can save 13,140 tons of coal per year. Furthermore, spraying a nano-high-entropy ceramic coating also effectively reduces the risks of high-temperature oxidation and wear, enhancing the unit’s adaptability to different coal types. The results of the above studies indicate that nano-high-entropy ceramic coatings possess significant anti-coking, high-temperature corrosion resistance, and energy-saving benefits, providing an effective strategy for protecting the furnaces of peak-shaving coal-fired power plants and conventional coal-fired units that use high-alkali coal from Zhundong. The research results of this project will be extended to provinces such as Gansu, Xinjiang, Qinghai, Inner Mongolia, and Ningxia, providing technical support for the transformation of coal-fired power in China into a fundamental, supporting, and regulatory energy source, as well as for the clean and efficient utilization of high-alkali coal in Xinjiang. This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Category A), Huaneng Lanzhou Xigu Thermal Power Co., Ltd., Xi’an Thermal Power Research Institute Co., Ltd., Gansu Electric Power Changle Power Generation Co., Ltd., Dongfang Electric Group Dongfang Boiler Co., Ltd., and TBEA Xinjiang Tianchi Energy Co., Ltd.