Ultra-supercritical power generation, what is the "super power"?

Zigzag development through more than 70 years

The concept of ultra-supercritical power generation is not new in the field of technology, since it was originally proposed, it has been developed in the world for more than 70 years, which can be roughly divided into three stages.

The first stage, starting from the 1950s, was represented by the United States, Germany and the Soviet Union, and directly developed ultra-supercritical power generation technology without experiencing the transition of supercritical parameters. However, due to the frequent failure of many ultra-supercritical units, from the late 1960s, these countries generally reduced the steam parameters of newly built units to the supercritical range.

The second stage, from about the early 1980s, supercritical technology was consolidated and developed. With the development of material technology, especially the substantial improvement of the material properties of boilers and steam turbines, and the in-depth understanding of the water chemistry of power plants, the series of failures encountered by early supercritical units have been overcome one by one.

In the third stage, from about the 1990s, ultra-supercritical power generation technology was reborn. With the increasingly stringent international environmental requirements, as well as the successful development of new materials and the maturity of conventional supercritical technology, the development of ultra-supercritical technology has better conditions. Represented by Japanese (Mitsubishi, Toshiba, Hitachi) and European (Siemens, Alstom) technologies, the use of higher steam temperature and pressure has become the mainstream trend of thermal power technology development under the premise of ensuring high reliability and high availability of units.

In China, the application of ultra-supercritical technology started late, but the development speed is rapid, and has gone through the entire process of technology transfer in the early stage and independent research and development in the later stage. In the second half of 2003, the Ministry of Science and Technology included the selection of parameters and capacity of ultra-supercritical units in the "863" scientific and technological research topics, and began the development of ultra-supercritical thermal power units. Subsequently, Harbin Electric Group, Shanghai Electric Group and Dongfang Electric Group introduced 1000 MW ultra-supercritical technology from Japan's Mitsubishi, France's Alstom, Germany's Siemens, Japan's Hitachi and other companies, and began to build 1000 MW ultra-supercritical units. At present, ultra-supercritical efficient power generation technology and demonstration projects have been promoted across the country, accounting for 26% of the total installed capacity of coal power. China has become the country with the fastest development, the largest number, the largest capacity and the most advanced operation performance of 1000MW ultra-supercritical units in the world.

Material innovation research and development look forward to breakthroughs

In order to further reduce energy consumption and reduce pollutant emissions, improve the environment, with the support of the development of the material industry, ultra-supercritical units in various countries are developing in the technical direction of higher parameters. This requires a further increase in the temperature and pressure of the steam at the boiler outlet. Current supercritical alloy materials can withstand up to 630 ° C temperature range. To further increase the steam temperature of the boiler outlet, it is necessary to develop more advanced alloy materials with higher temperature resistance, and through the research and development of supporting welding, manufacturing process and other systems, to minimize the use of expensive high-temperature alloy materials on the basis of ensuring safety. Therefore, material cost and key equipment manufacturing process are currently the biggest obstacles affecting 700℃ advanced ultra-supercritical power generation technology.

At present, the research and development of 700℃ advanced ultra-supercritical technology being carried out by the world's major economies can be considered as an important direction of the development of ultra-supercritical technology. In this regard, the European Union started the first, officially launched the AD700 advanced ultra-supercritical power generation program in January 1998. The original plan was to realize the commercial operation of the unit around 2011 through the operation and technical improvement of the demonstration power station. However, due to the high temperature alloy steel and austenitic steel prices are expensive, and the relatively cheap ferritic steel performance has not reached the expected target, the investment of the entire project will be greatly increased, resulting in the delay of the plan. There are currently no concrete plans to build demonstration plants in the EU.

The United States, Japan and other countries also have their own plans in the development of advanced ultra-supercritical technology, and there are no relevant reports of commercialization.