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Domestic backpressure thermoelectric distributed energy projects are supported by national policies!
Recently, the "Decision of the National Development and Reform Commission on Amending the Relevant Terms of the
Through this adjustment, backpressure (back-pulse) cogeneration has been included in the encouragement category, which has received recognition and support from policies and has also attracted widespread attention from the industry. So, what are the advantages of backpressure thermoelectricity? Why is it listed as an encouragement category? What impact will this have on the development of backpresses? What opportunities and challenges are faced with the development of backpressure thermoelectricity at present? With these questions in mind, the reporter conducted an interview a few days ago.
"Among many generator sets, backpressure cogeneration units can achieve efficient energy utilization because they eliminate the heat loss of the condenser." said Wang Zhenming, consultant to the Thermal Power Committee of the Chinese Society of Electrical Engineering.
According to experts, backpressure units are generators that use thermal load to adjust power generation load. The amount of steam the gas turbine enters, the unit emits as much steam, truly realizing the "heat-determining electricity". At the same time, the unit's thermal efficiency can be as high as 80%-90%, which is far higher than the current thermal efficiency of large ultra-supercritical units in China, and is an excellent energy-saving and environmentally friendly unit.
"Previously, the cogeneration unit was mainly steam extraction unit." Wang Zhenming said that the steam extraction unit made a hole in the steam turbine and extracted a part of the steam to supply steam to the outside, while the remaining steam was used to generate electricity. It can not only achieve external heating while generating power, but also operate as a pure generator set. "This type of unit has an advantage, that is, it can be actively adjusted to adapt to changes in external electrical and thermal loads and ensure the economic operation of the unit."
"But when the steam extraction unit is running, there will be a cold source loss, and its thermal efficiency will be reduced accordingly." Wang Zhenming said that in comparison, the backpress is the highest in terms of thermal efficiency since the condenser eliminates the cold source loss of the condenser.
But backpressure units also have their disadvantages.
"Since the unit's electrical load depends entirely on the external thermal load, the unit's regulation capacity is relatively poor." Wang Zhenming said, "In addition, when the thermal load is low, the efficiency of the backpressure unit will decrease, which also leads to a reduction in its economic benefits."
According to Wang Zhenming, in the previous era of the Ministry of Energy, my country was also vigorously promoting backpressors for a period of time. If the cogeneration project approved at that time did not use a backpressor, it would be difficult to obtain approval, which led to a large number of backpressure unit projects being launched at that time. However, due to the above shortcomings of the backpressor, the unit did not achieve the ideal results after it was put into production. For example, a backpressure unit project was built in Shaoyang Investment, Hunan at that time, but the area is located at the end of the power grid and the steam is low. In order to meet the local electricity load needs, the unit can only open a hole and discharge steam into the sky. This operation method has caused considerable waste.
Two subjective and objective factors contribute to policy encouragement
"There are two main reasons why backpressure cogeneration is listed as an encouragement category." Wang Zhenming said that on the one hand, through so many years of cogeneration development experience, people have gained a relatively full understanding of various cogeneration units; on the other hand, with the development of the economy and society, many regions have formed a relatively stable heating market with large steam consumption, which has created good development conditions for backpressure thermoelectricity.
"As people deepen their understanding of unit performance, power plants currently use backpressures and steam condensation units when applying backpressures. Backpresses are generally used as base loads, while steam condensation units undertake load regulation tasks." According to Wang Zhenming, at present, the backpressure cogeneration unit can achieve a power generation coal consumption of less than 200 grams/kilowatt-hour when operating at full load. Although the power generation coal consumption of steam condensation units may be as high as 400 grams/kilowatt-hour, the two can complement each other's advantages when used together, achieving good economicality.
But in fact, there are currently all cogeneration enterprises that use backpressors. Taking Shengzhou Thermal Power Plant in Shaoxing, Zhejiang as an example, all the plants use backpressure units. "There are two main reasons why the full backpressure unit can be operated." Wang Zhen said that first, the power plant has been developing in the local area for many years, forming a relatively stable and large-scale heating market, and the unit's thermal load has a certain degree of guarantee; second, the backpressure unit of the plant adopts a configuration method combining large, medium and small to achieve adjustment of heat load changes.
Obtained attention to application and gained a good opportunity for development
According to reports, cogeneration of heat and power is currently the most efficient energy utilization method, and every 10,000 kilowatts of installed capacity saves 10,000 tons of standard coal per year compared with thermoelectric distribution. Data shows that in the 12th Five-Year Plan, my country's new cogeneration installed capacity was about 110 million kilowatts. By 2015, my country's cogeneration installed capacity will reach 250 million kilowatts, accounting for 32% to 35% of the thermal power installed capacity plan, which can reduce the energy consumption per unit GDP of the power industry by 3% to 5%.
"But we have learned that there are currently many cogeneration units in my country that are suspected of fake thermoelectricity. These units have almost no heating or have a tiny amount of heat supply." A person who has been engaged in the thermal power industry for a long time revealed to reporters, "Only the backpressor is the real cogeneration, and it truly follows the development principle of 'heat-based electricity'."
"However, in recent years, backpressors have not received the attention they deserve. There is little support from preferential policies in terms of project investment and power on-grid electricity prices." The above-mentioned person said, "and this time it is listed as an encouragement category, it can be said that the cogeneration of backpressors has received due attention, which also shows that the development of backpressors has been on track to a certain extent."
It is also understood that backpressure cogeneration units also have incomparable advantages in centralized heating in northern cities in winter. "But because some staff from relevant government departments did not have a special understanding of backpresses in the past, they have never been in place in policy formulation, which has not fully utilized the advantages of backpressor cogeneration." An urban heating expert from the Ministry of Housing and Urban-Rural Development said, "This time it was included in the encouragement category, which can be said to be a huge opportunity for the development of backpressure cogeneration."
Wang Zhenming also believes that: "This time it is listed as an encouragement category, and the decentralization of the approval authority for backpressure project is a great thing for the development of backpressure thermoelectric projects."
Facing strong competition for large units
However, there are also opinions that the development prospects of backpressure cogeneration are by no means flat, and it can even be said to be in danger.
It is understood that the capacity of backpressor assembly is usually below 50,000 kilowatts, and the units are relatively small, while the current trend of large-scale generator sets in my country is obvious. "At present, a considerable number of projects have listed high-parameter and large-scale units as priority choices, and the possibility of pure generators below 600,000 kilowatts being approved is getting approval." According to the above-mentioned person, there are currently units below 300,000 kilowatts and below, and losses have occurred frequently in recent years. If it is not cogeneration, units with installed capacity of 300,000 kilowatts and below are almost doomed to suffer losses. Therefore, many units with a capacity of 300,000 kilowatts or less have been heated. However, the heat supply of some units after renovation is quite limited, and there is still condensation loss, so the efficiency is still not as good as that of the backpressure unit.
"But 300,000 kilowatt or 600,000 kilowatt thermoelectric units will create huge competitive pressure for much smaller backpressure units. Because large units are strong in most cases." The above-mentioned person said, "In the trend of large-scale units, the future of backpressure cogeneration is difficult to say. And it is likely to be merged by large-scale thermal power units."
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