In the long river of human social development, energy has always been an important force to promote civilization and progress. In order to obtain more efficient energy and reduce the environmental burden as much as possible, human beings constantly challenge the limit of energy conversion, and ultra-supercritical generator sets are one of them.
Changzhi Power Generation Company in Shanxi Province operates two ultra-supercritical direct air-cooled coal-fired generating units, which were completed in May 2021 and successfully passed the 168-hour full-load trial operation before being put into commercial operation.
The application of ultra-supercritical power generation technology makes the combustion efficiency of coal higher, and at the same time, it emits less pollutants such as carbon dioxide and is more environmentally friendly. It is of great significance to practice the goal of "double carbon".
Changzhi Power Generation Company Minimizes Unit Energy Consumption (photo by Liu Hongrun and Ren Wuzhong)
Reach the leading level of coal-fired power generation efficiency
"At 18 o’clock, the unit load of Unit 2 of the company rose to 920MW." A few days ago, Guo Jinghu, a staff member of the power generation operation department of Changzhi Power Generation Company, received an instruction from power grid dispatching, indicating that the power plant needs to increase the load of late peak units. At full load, the units here can generate 1000MWh per hour, which is the leading level of coal-fired power generation efficiency in the world at present.
Coal saving is the biggest advantage of ultra-supercritical technology, which improves the thermal efficiency by 2% to 3% compared with the most advanced supercritical units in China. If the thermal efficiency is increased by 1%, for a 1000MW thermal power unit, about 2.5 grams of coal can be saved per kWh of electricity, 27,500 tons of high-quality coal can be saved in one year, and the carbon dioxide emission can be reduced by about 72,000 tons.
While maintaining its availability, reliability, operational flexibility and unit life, the ultra-supercritical generator set further improves the steam parameters and "eats dry and squeezes clean" each gram of coal, thus achieving higher power generation efficiency and environmental protection performance, and improving the production efficiency and economic benefits of the generator set.
According to reports, at present, the mainstream coal consumption level of thermal power plants is about 300 grams to 330 grams per kWh, and the ultra-supercritical generator set can reach the coal consumption level of 265 grams per kWh under design conditions. If the coal consumption drops by as little as 10 grams, the technology will be one generation behind. In China, coal-fired generating units burn about 2 billion tons of coal a year. If all ultra-supercritical power generation technologies are adopted, a seemingly small change of 10 grams will save tens of millions of tons of coal.
Has achieved a "carbon surplus" for two consecutive years.
Changzhi Power Generation Company is the main power generation enterprise under Jinneng Holding Shanxi Electric Power Co., Ltd., and it is also the first million-kilowatt power plant in Shanxi Province to realize the commercial operation of two machines.
As an important supporting power supply project of 1000kV UHV in southeastern Shanxi-Jingmen, Changzhi Power Generation Company has exported more than 17 billion kWh of electricity to Shandong, Beijing, Tianjin and Tangshan since it was put into production, which is of great significance to promoting the continuous improvement of atmospheric environmental quality in Beijing, Tianjin and Hebei. At the same time, following closely the national energy industry policy, the company began to provide central heating to Changzhi urban area in November 2022, and adopted the heating mode of combining unit extraction with exhaust steam waste heat, which increased the thermal efficiency of the whole plant to 46.5%, with a heating area of 15 million square meters and a total heat supply of 8.85 million Ji Jiao, creating a precedent for one million units to undertake urban central heating. In addition, the company actively promotes the transformation of heating capacity. In 2024, it plans to add a first heating station with a heating capacity of more than 10 million square meters and related supporting facilities to further reduce the coal consumption of power supply.
"Left-handed" economy, "right-handed" environmental protection. "Coal-fired power is a key industry for carbon dioxide emissions in China’s power sector. Coordinating the prevention and control of air pollution and the goal of’ double carbon’ is a key task for some time to come." Zhang Jun, deputy director of the company’s environmental protection department, said that in recent years, Changzhi Power Generation Company has actively implemented the goal of "double carbon" and accelerated the research and transformation and application of green and low-carbon technologies, and has achieved a "carbon surplus" for two consecutive years, with a total of more than 700,000 tons.
Zhang Jun said that the reason for this achievement is that on the one hand, the project is supporting the construction of the most advanced flue gas desulfurization, denitrification, dust removal and water treatment facilities, and the total emissions of sulfur dioxide, soot and nitrogen oxides are lower than the national standards, and the power generation energy consumption is low; On the other hand, the ultra-supercritical generator assembly machine has large capacity, high technical parameters, stable equipment operation, good heat supply and power generation indicators, and remarkable achievements in clean and efficient utilization of coal, energy conservation and environmental protection.
Exterior view of Changzhi Power Generation Company’s workshop (photo by Liu Hongrun and Ren Wuzhong)
Strive to build a green and low-carbon thermal power industry
"This is the 3D real-time dynamic map of No.1 circular coal yard. The red tower standing in the center of the coal yard is an automatic stacker-reclaimer, with a height of 23.9 meters and a length of 28 meters. Laser scanners are installed on both sides, and one-button remote control is used to automatically take and transport coal. The whole process does not require manual intervention, and the efficiency of stacking and taking coal is improved by more than 10%." Li Li, the person in charge of coal transportation operation in Changzhi Power Generation Company, pointed to the electronic display screen in the dispatching room. Three-dimensional image data can accurately calculate the coal stack structure, the cutting position of stacking and fetching, remotely control the movement of the fetching arm and the speed of the scraper, and scientifically mix coal, which can save 400,000 kWh of auxiliary power throughout the year.
Through intelligent transformation such as big data analysis, intelligent robot application and "automatic material taking" and remote coal feeding, Changzhi Power Generation Company is constantly moving towards the goal of high-end, green and intelligent.
"Because of the fluctuation and intermittence of new energy, thermal power units are still needed to play the role of’ stabilizer’ and’ ballast stone’ for the safe operation of the power grid." Wang Zhen, production management department of Jinkong Electric Power Co., Ltd. introduced that the minimum technical output of 20 thermal power units owned by Jinkong Electric Power Co., Ltd. can reach below 35% under pure power generation conditions, and it has the ability to quickly add and subtract loads. In the future, the company will further accelerate the development of new quality productivity, continuously promote the clean and efficient utilization of coal, and strive to build a green and low-carbon thermal power industry, contributing to the rapid, stable and coordinated development of the province’s economy and the continuous improvement of atmospheric environmental quality.
interlinkage
[Ultra-supercritical power generation]
Ultra-supercritical power generation refers to the technology of converting water vapor into electricity at high temperature, high pressure and high density by using ultra-supercritical boilers and steam turbines when burning traditional fossil fuels (such as coal and natural gas). According to the principle of thermodynamics, the higher the pressure and temperature of water vapor, the higher the power generation efficiency. At the pressure of 22.129MPa and the temperature of 374.15℃, the density of water vapor, like liquid water, reaches a critical state. When the temperature and pressure both exceed the critical value, water will be in a supercritical state. The technology of using supercritical water vapor to generate electricity is called supercritical power generation technology. The steam temperature in the furnace is not lower than 593℃ or the steam pressure is not lower than 31MPa, which is called ultra supercritical. The temperature and pressure of ultra-supercritical power generation are higher than that of supercritical power generation, which is a higher stage of supercritical power generation. (He Kai Liu Hongrun Ren Wuzhong)
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