Nuclear heating takes steam from the secondary circuit of the nuclear power unit as the heat source, carries out multi-level heat exchange through the initial heat exchange station in the plant and the heat exchange station of the heating enterprise outside the plant, and finally transfers the heat to the end user through the municipal heating network.
Winter has arrived, and more than half a month has passed for heating in many parts of the country. Unlike before, this year's heating has a "new pattern" - nuclear heating.
Nuclear heating has been in mature operation for more than 40 years in northern Europe, Russia and other places. The pressurized water reactor unit of nuclear combined heat and power has been in safe operation for 1000 reactor years. In China, nuclear heating has also been brewing for many years, and has been actively supported by relevant departments of the state, but has never been substantially broken.
Recently, "national energy nuclear power heating commercial demonstration project" was unveiled in Haiyang nuclear power plant, which opened a new situation of multiple use of nuclear power in China, with milestone significance.
It's natural for skill progress to bring expansion of heating radius
"It's a natural job." Wu Fang, chairman of Shandong nuclear power, commented on the arrival of the heating season this year after years of incubation.
On the one hand, it is the expansion of heating radius brought by the progress of skills.
The latest version of regulations on environmental radiation protection of nuclear power plants implemented on September 1, 2011 clearly stipulates that the distance between the boundary of non residential areas with permanent residents and the reactor shall not be less than 500m; there shall not be towns with more than 10000 people in the scale of the planned restricted area, and there shall not be towns with more than 100000 people within the scope of 10km of the plant site.
This red line defines the shortest radius that nuclear heating can reach. According to Wu Fang, due to the constraints of heat preservation skills and materials, the heating interval in the past can not be too far, and it is usually not reliable if it exceeds 10km; however, with the progress of skills, long-distance heat transfer becomes more and more feasible, and now there are many successful cases in China, such as the ancient Jiaotong long-distance transport (more than 40km), ebarping long-distance transport (67km), etc. Some long interval heat transfer projects under planning and construction can reach 70 km.
"There are no technical constraints on the distant heat transfer of nuclear power." According to Wu Fang, combined with the new skills such as large temperature difference, absorption heat pump, selection and optimization of thermal insulation materials, relay pump station, the heat transfer interval can be as far as 100km. The distance between Haiyang nuclear power station and Yantai, Weihai and Qingdao is about 100 kilometers, so the heating radius can cover up the smoke, Qingwei, etc.
He leakage, the heating area is 700000 square meters this time; after the transformation of Haiyang nuclear power plant units 1 and 2 in the future, a single unit will have a maximum heating capacity of 30 million square meters in 2023. According to the calculation that two units are standby for each other, it is planned to complete the heating scale covering 60 kilometers around the plant site and an area of 30 million square meters in 2023.
It is natural for nuclear power to replace coal with waste heat
On the other hand, it is the development trend of green and low carbon.
In the past, the use of residual heat in nuclear power plants was limited to self use in the plant site. The existing nuclear power stations in the North heating area visited by the reporter, such as Liaoning Hongyanhe Nuclear Power Station, xudabao nuclear power station and Jiangsu Tianwan nuclear power station, including Haiyang nuclear power station put into operation last year with No. 1 and No. 2 units, whose waste heat is used to heat the plant in winter, are nothing new.
"At the end of the day, the thermal power of a thermal power plant is constrained to a certain extent and cannot reach 100%." Zhang Zhen, an engineer from Shandong Nuclear Power Planning and management office, explained, "now the thermal power of coal-fired power units has improved to more than 50%, while that of nuclear power is less than 40%. This means that a lot of waste heat is generated, "you use it or not, it's there."
For a long time, haze has become the "standard" of heating season in the north, which is boring and helpless. In recent years, after the "coal to electricity" and "coal to gas" efforts to show results, it is natural for people to put the alternative heat source of coal-fired heating into the same clean nuclear power.
"With the support of heat preservation skills and equipment, the heating coverage scale has been extended, and nuclear heating has come into being." Wu Fang said so.
Safe only heat exchange without water touch
The common water tower of coal power plant and the drain outlet of nuclear power plant are the outlet of residual heat. The drain outlet of nuclear power plant only uses water to remove the residual heat, and the water is transported in the closed pipeline, so there is only heat exchange, no water touch, and no radiation. What's more, because the temperature of the outlet of the nuclear power plant is slightly higher than that of the seawater, there will be a lot of fish gathering nearby in winter.
In fact, the safety of nuclear heating can be proved by the side evidence of the above-mentioned nuclear power plant's own residual heat heating - they are most aware of whether it is safe or not.
As for the most concerned question of the public, Wu Fang replied from the skill level: "nuclear heating is a partial skill transformation based on the existing unit power generation. Power generation is still the main business, and heating is only a by-product. "
Nuclear heating is to extract steam from the secondary circuit of the nuclear power unit as the heat source, carry out multi-level heat exchange through the initial station of heat exchange in the plant and the heat exchange station of the heating enterprise outside the plant, and finally transfer the heat to the end user through the municipal heating network. In the whole process, there are only two processes of steam heating water and water heating water, and five circuits are set between the nuclear power station and heating users to block. There is only heat exchange between each circuit, no water touch, and no radioactivity. The hot water in the user's heating pipeline is only closed and circulates in the residential area, which is very safe and barrier to the nuclear power plant.In addition, there are many monitoring methods in the power plant, which can detect any fine abnormality. So nuclear heating must be reliable and safe.
Multi win economy comparable to large coal power cogeneration
"We have calculated that the economy of cogeneration of nuclear power plants can be equal to that of large coal-fired power plants." Wu Fang summed up the demonstration project with "no increase in the price of residential heating, no increase in the financial burden of the government, no damage to the interests of thermal power companies, contribution from the operation of nuclear power enterprises, and significant improvement in ecological and environmental benefits".
Reporters in the local Fengyuan thermal power company "the first station of nuclear heating" saw that the original 65 tons of coal-fired boiler has been out of operation. Zhao Xin, chairman of Fengyuan Thermal Power Co., Ltd., said that in the past, coal-fired boilers used to generate a lot of noise and require many operators. Now the heat exchange station can be unattended, saving labor costs.
Zhao Xin indicated that after 700000 square meters of nuclear energy heating was completed in the first phase of the demonstration project, the most intuitive role was that the Fengyuan thermal chimney around the Fengcheng national travel and vacation area did not smoke. If 200 million square meters of nuclear energy heating can be completed in the future, 6.6 million tons of coal, 20 million tons of carbon dioxide and 103 thousand tons of nitrogen oxide can be reduced annually.
How to achieve such a win-win situation? According to Wu Fang's analysis, nuclear power plants are traditionally pure power generation, with relatively low power consumption of thermal energy. The comprehensive use of nuclear energy can instead improve the thermal power of nuclear power plants. He estimated that in the future, if the heating area is expanded to the surrounding 4.5 million square meters, the thermal power of Haiyang nuclear power plant can be improved from the existing 36.69% to 39.94%.
Qian Zhimin, chairman of the State Power Investment Corporation, believes that nuclear power should be used as the basis to achieve the expansion of nuclear power to nuclear energy and the expansion of single nuclear power to multiple energy comprehensive use through the complementary and joint efficient operation of nuclear power generation, nuclear heating, desalination, integration of electric energy storage and optical energy storage, and hydrogen energy.
