The hard "core" force behind zero-carbon heating

Extraction of steam from large nuclear power units for heating

Cogeneration has taken a new path for the comprehensive utilization of nuclear energy

Outside, the wind was blowing and the temperature dropped below freezing. However, in the home of Ms. Hou, a resident of Yasha Village in Haiyang City, it is warm as spring.

"There is no one living next door to my house, upstairs or downstairs, but the house is still very warm. The thermometer shows that the temperature in the room has reached 26 degrees Celsius. The temperature is more stable than before when we used to burn coal for heating." Ms. Hou said, holding a thermometer.

In Haiyang, there are many people who have the same feelings as Ms. Hou. And this is exactly the "warm nuclear No. 1" project put into operation to Haiyang City residents brought about immediate changes.

The reporter learned that "warm core No. 1" is a nuclear zero-carbon heating technology developed by the state power investment with completely independent intellectual property rights, and is also China's first comprehensive utilization of nuclear energy technology brand. This year is the second year that Haiyang City uses this technology to achieve nuclear heating.

Zhang Zhen, Shandong nuclear power design and management engineer. Although he is young, he has witnessed the whole process of innovative practice of comprehensive utilization of nuclear energy.

"Nuclear is more than electricity." Zhang Zhen told reporters that in most people's concept, when it comes to nuclear energy, the first thing that comes to mind is power generation, but in fact "nuclear energy has more possibilities", cogeneration is one of them, "that is, both power generation and heating."

According to him, as the first nuclear power plant in Shandong Province to start construction and put into operation to generate electricity, Haiyang Nuclear Power plant plans to build 6 million kilowatt nuclear power units, reserving two room for expansion, with a total installed capacity of more than 10 million kilowatts. The two units of the first phase of the project are national third-generation nuclear power independent projects, which began to be connected to the grid in October 2018 and January 2019, respectively.

Prior to this, Wu Fang, chief engineer of nuclear energy development of State Power Investment Group Co., LTD., Party secretary and chairman of Shandong Nuclear Power Co., LTD., put forward the idea of nuclear energy heating, and led the team to take the lead in the research and practice of large-scale pressurized water reactor cogeneration. At that time, Shandong Nuclear Power developed a "three-step" strategy: the first phase of the park level auxiliary steam heating module (heating capacity 30 MW), the second phase of the county level extraction steam heating module (heating capacity 200 MW), the third phase of the regional level large-scale extraction steam heating module (heating capacity 900 MW) and other technical standardization programs. This set of nuclear heating technology is named "warm nuclear No. 1".

According to reports, the heating principle is from the Haiyang nuclear power unit to extract some of the steam that has been generated as a heat source, in the case of physical isolation, multiple heat exchange, and finally warm to the user's home. But these seemingly easy steps are not so easy to do.

"For the technical proposal alone, we designed nine different routes at that time. Whether it will be done, whether it will be accepted, those are the questions." Zhang Zhen told reporters.

In the winter of 2019, the 31.5 MW project of the first phase of "Warm Core No. 1" was put into operation, achieving heat supply to the surrounding 700,000 square meters, which is the first nuclear energy heating commercial project in China. At that time, the staff dormitory area and construction living area of the nuclear power plant took the lead in using nuclear energy heating, and the project was named "National Energy Nuclear energy heating commercial Demonstration Project" by the National Energy Administration.

But Zhang Zhen and his colleagues could not "breathe", and then they had to tackle the 202.5 megawatt project of the second phase of "warm nuclear No. 1", involving nearly 5 million square meters.

"Different from the first phase of the project, the second phase of the project to achieve a wider range of heating, the need to high-pressure cylinder exhaust pipe, valves, heat exchangers and a series of physical equipment to be reformed, but also involves a change in the control scheme." Zhang Zhen further explained that, for example, we have to pump more than 300 tons of steam from the high-pressure cylinder at one time, and the sudden change in pressure is bound to affect the operation of a series of equipment such as steam turbines.

Therefore, in the end how much to smoke, how to smoke, every link must not be careless. Finally, through multi-party cooperation, the project team has overcome a series of key technologies of "warm core No. 1" : filling the domestic gap in the extraction technology of the million-kilowatt medium pressure saturated turbine unit; New valves, such as large-diameter extraction check valve and quick-closing regulating valve, which are suitable for saturated steam, have been developed, which are the first in China in the key equipment of nuclear power cogeneration. The operation control strategy of matching reactor thermal power with turbine generator power + external heating power is developed, which makes a new leap in the operation control technology of nuclear cogeneration. Formed a complete set of safety and transient evaluation system based on nuclear power cogeneration, achieved zero breakthrough in the safety evaluation technology of domestic large nuclear power unit cogeneration...