Gas turbine power unitIt is a gas turbine and is used to generate useful power (e.gelectric energy, mechanical energy or thermal energy).The simple cycle gas turbine is the simplest thermal cycle gas turbine and the most commonly used gas turbine at present.Single loop is the simplestGas turbine cycleThermal cycle of gas turbine.The higher the maximum temperature of the cycle, the higher the efficiency, and vice versa.The inlet temperature of the general gas turbine cycle is the atmospheric temperature, which has a relatively small change value determined by the earth's climate conditions. Therefore, the first factor to determine the efficiency is the maximum temperature of the cycle, that is, the inlet temperature of the gas turbine (usually called T3), which is usually a characteristic quantity to measure the performance level of the gas turbine.
At present, the combined cycle refers more to the gas steam combined cycle, including feedwater heating type, waste heat boiler type, exhaust gas supplementary combustion type and exhaust gas fully fired type. At present, most of the actual combined cycles are waste heat boiler type combined cycles.
The system is mainly composed of gas turbine, steam turbine, generator, heat exchanger, pump, etc.In the combined cycle unit, the air is compressed by the air compressor and sent to the combustion chamber. The compressed air is mixed with the injected fuel and burned to form high-temperature and high-pressure gas. The gas working medium with the ability to do work enters the combustion turbine for expansion;After work, there is still gas with higher temperature enteringWaste heat boilerAt this time, the waste heat of the fuel gas converts the water in the steam water system into high-temperature and high-pressure steam. The steam working medium with the ability to do work enters the steam turbine for expansion and work. The exhaust steam of the steam turbine is cooled into water by the condenser, heated by heaters at all levels, and then enters the waste heat boiler to complete the steam cycle;Low temperature flue gas from waste heat boiler after heat exchange between gas and water is discharged into the atmosphere through flue to complete gas circulation.This is the working principle of a typical waste heat utilization type combined cycle power generation system.
Advantages of gas power generation
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gas turbineSince stepping onto the power generation industry stage in the 1950s, its power generation efficiency and thermal efficiency have been greatly improved, especially the gas steam combined cycle unit has become increasingly mature. The single unit power of the gas turbine has exceeded 334MW, and the thermal efficiency has reached 35%~41.92%, while the single unit power of the combined cycle unit has reached 489.3MW, and the thermal efficiency has exceeded 60%,It provides technical support for the improvement of gas power generation in the power system.
The experience of European and American countries shows that, starting from the requirements of safety and peak shaving, the power share of 8%~10% should be installed in the power gridGas turbine generator setIt is necessary.The difference between peak and valley of power grids in many regions of China is relatively large, and it is urgently needed to start quickly, have good peak shaving performance and short construction periodgas turbineAnd its combined cycle to meet the needs of construction, especially in coastal open areas.
Natural gas combined cycle power generation combines natural gas cleanness and combined cycle efficiency, and has many advantages. It has become the most popular practical power generation technology in the world today.At present, 35% - 36% of the world's annual increase in power generation capacity is gas steam combined cycle units, while 48% in the United States. Among the new power plants built in the United States from 2000 to 2004, natural gas power plants accounted for 93%.
High thermal efficiency: natural gas power generation has high thermal efficiency."G" and "H" levels just launched or under development by major companiesgas turbineThe initial gas temperature reaches 1427 ℃, the single unit capacity of the simple cycle is 280MW, and the combined cycle capacity is about 520MW, and the thermal efficiency has exceeded 60%.
Less investment: The unit installed capacity of natural gas power generation requires less investment and is cheap. At present, the investment cost per kilowatt is only 4000~5000 yuan/KW, or even lower, while the investment in steam turbine power plants is as high as 8000~11000 yuan/KW.
Short construction period: its equipment is composed of components, light in weight and fast in construction. It can be put into operation in 12 to 20 months, generally 43% of the construction period of thermal power units;In addition, due to the lack of civil engineering, it can be built in stages. First, the gas turbine power plant will be built, and then the combined cycle power plant will be built, so as to maximize the efficiency of funds.
The floor area is small, generally 50% of that of coal-fired power plants;Water consumption is only about 30% of that of coal-fired power plants.
Reliable operation, high automation, and the number of operators can be greatly reduced.The daily operation and management personnel required are only 2% of the general coal-fired power plants.
Current situation of domestic gas-fired power generation
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For a long time, China's energy structure has been dominated by coal, which determines the dominant position of coal in China's power generation energy structure.However, from the perspective of environmental protection, the pollution emission of coal power is very serious and has not yet been effectively controlled, which has become a "bottleneck" that restricts the implementation of the sustainable development strategy of China's power industry.Therefore, in addition to developing environmental protection devices for coal-fired power plants, we must also adjust our energy structure, that is, replace some of the coal used for power generation with high-quality clean fuels, such as natural gas.Gas turbine and its combined cycle generator unit burning natural gas are the preferred technology to improve the utilization efficiency of energy resources and solve the environmental pollution problem quite thoroughly.
In the current diversified energy development, the production of coal will also rise steadily, but its proportion in energy will be relatively stable, and the development speed of gas fuel will be relatively accelerated.The gas fuel supplied for combustion power generation can only be used in the combined cycle, not forutility boiler This is also the latest domesticgas turbineThe main reason for the increase in demand.It is expected that in the near future, the proportion of gas fuel consumption in China will continue to rise, and the demand for gas turbines will also continue to grow.
Since 2004, the state has arranged 40 sets of gas steam combined cycle power generation projects in two bundles of bidding, using "F" class gas turbine units to form a combined cycle of natural gas transported from the west to the east and imported liquefied natural gas (LNG), with each set of 400MW.In 2005, nearly 20 sets of bundling bidding projects were completed.In addition, with the gradual development of offshore marine natural gas resources (such as the East China Sea near Shanghai and the South China Sea near Hainan Island), it is likely thatGas turbine power generationThe sustainable development of the industry provides resource support. For example, Hainan intends to use the natural gas resources in the South China Sea (with reserves of 380 billion m3) to establish a natural gas power generation base to transmit power to Guangdong.In addition, according to China's energy planning, the southeast coastal areas will import a part of liquefied natural gas (LNG) from neighboring countries as supplementary energy. For example, the LNG project in Guangdong Province has been started. The first phase project was completed in 2005 and began to supply gas. In 2007, the supply of gas will reach 325 t/a, and the supply of the second phase project will be expanded to 500 t/a.Fujian Province has also decided to import 200t/a from Indonesialiquified natural gas。
Entrusted by the state in 2004China National Technology Import and Export CorporationAccording to the policy of market for technology, there are only 17gas turbineThe power station construction project implemented bundled bidding, which introduced some manufacturing technologies of PG9351FA, M701 and V94.3A gas turbines and equipment of more than 40 gas turbines and their combined cycle units.According to incomplete statistics, at least 41 F type and more than 20 "E" type gas turbines and their combined cycle units were put into operation in China in 2008. In the future, the types of gas turbines in China's power system will be mainly positioned in "F" and "E" type units.
In short, with the development and application of natural gas resources, the number ofGas generator setThe role of gas power generation in China's power industry will gradually increase.
