China is a country with coal as its main energy source. It has a long history of coal mining and has formed hundreds of millions of cubic meters of mining space each year in coal mining. At the same time, a large number of mines have been scrapped due to the depletion of resources. According to statistics, between 1953 and 1998, 459 mines in China's state-owned key coal mines were scrapped. Of the 82 state-owned key mining bureaus surveyed by the China Coal Information Research Institute, 69% of the mining bureaus have scrapped mines. The reuse of abandoned mines in coal mines has become an important part of the green safety production of coal mines. In recent years, the secondary use of abandoned underground mines has attracted the attention of many scholars. The research team led by Academician Qian Minggao of China University of Mining and Technology The serious mining disaster caused by extensive coal mining, environmental damage and resource waste, the first concept of realizing green mining of coal resources has been highly concerned by academic and industrial circles. 3. China University of Mining and Technology (Beijing Campus) Related research has been done on the safe disposal of industrial waste using underground waste space. Henan Polytechnic University has studied the technology related to the storage of CO2 in the abandoned mine goaf. 4. In foreign countries, Germany used two abandoned mine roadways in the rock salt layer as a gas storage chamber in 1978, and established a rated power of 290MW. The Fendorf compressed air universal power station with a power generation capacity of 4h has been commercialized to date. 5. From 2001, Ohio, USA, built a 2700MW large compressed air using a cavern of underground rock salt at 670.6m underground as a gas storage room. Energy storage commercial power station. Since the 1990s, the Japan New Energy Foundation and the Electric Power Development Corporation have researched and built a 35MW compressed air test power station. In recent years, with the continuous expansion of the installed capacity of the domestic power grid, the peaking capacity of the power grid is generally insufficient, and it is urgently needed. A new type of peaking unit, which creates conditions for the construction of compressed air storage power stations using abandoned mine roadways, and the peak-to-valley time-of-use electricity price mechanism implemented in 2003 has ensured its economic feasibility. This paper proposes a compressed air storage power station system combined with abandoned mine roadway, and proves its technical and economic feasibility by examples.
1 Introduction to compressed air energy storage technology. The principle is: using the remaining power of the power system when the load is low, the motor is used to drive the compressor, and the air is directly pressed into the large-capacity storage chamber, so that the unburnable electric energy is stored in the gas storage in the form of compressed air pressure potential energy. In the room. When the grid load reaches a peak and the power generation capacity of the power system cannot meet the requirements, the compressed air is preheated by the heat exchanger and mixed with natural gas or oil. The flue gas is introduced into the gas turbine for power generation, thereby meeting the peaking demand of the system.
It has played a role in shifting peaks and valleys for the entire power system.
The start-up time is short, the emergency start can be completed within 9 minutes and the operation mode is flexible, and the pollutant discharge is less; the running cost is only 1/3 of that of the conventional gas turbine power plant of the same capacity; the unit cost is lower than the conventional gas turbine power station, but its The ability to adjust the peak-to-valley difference of the power grid and improve the power supply quality is more than twice that of the conventional gas turbine power station; the system performance is good, the energy storage and release can be tens of thousands of times, the service life can reach 40~50a, and the efficiency can reach about 70%.
2 The CAES power station combined with the abandoned mine is to make full use of the abandoned mine resources. In addition to using the roadway as a gas storage outdoor, the building and equipment of the original living area can be reconstructed and used as the living area of ​​the CAES power station. If it is a coal-fired cogeneration enterprise, it can continue to use the transmission line of the original power station, which can improve the investment cost of saving CAES power station. The key to the use of abandoned roadways as compressed air storage chambers is sealing. Due to the lack of experience in this aspect of China, we can learn from the more mature technology in Japan and adopt the rubber-lined sealing method. A compressed air storage power plant system combined with an abandoned mine is shown.
The energy storage subsystem of the compressed air storage (CAES) power station consists of a motor/generator-coupling-low pressure compressor-cooler 1-high pressure compressor-cooler 2 -valve 1 - mine roadway (storage chamber) In the process of compressed air storage, the air pressure in the mine roadway is directly changing, the compressor is always operating under variable working conditions, and the storage pressure of the gas is far greater than the air pressure at the gas turbine inlet. The system adopts the form of intermediate cooling two-stage compression, and its high pressure compressor pressure ratio is equal to the low pressure compressor pressure ratio. The power generation subsystem consists of a motor/generator-coupling-air turbine-combustion chamber-gas turbine-reheater-valve 2-mineway roadway (storage chamber). Due to the high pressure of the compressed air coming out of the mine roadway, in order to make full use of this part of the energy, the subsystem adds air turbine before the gas turbine, and uses the regenerator to preheat the air entering the turbine, improving the overall efficiency. . When the grid load is at a low point, the coupling 1 is connected and the energy storage subsystem operates to store the electrical energy through the compressed air. When the grid load is at a peak, the coupling 1 is disconnected, the coupling 2 is connected, and the power generation subsystem is operated to convert the energy stored in the compressed air into electrical energy to be integrated into the grid.
3 Case Analysis In order to improve the economic feasibility of using the compressed air storage (CAES) power station in the mine abandoned roadway, the author conducted an investment economic analysis based on the Xuzhou Quantai Coal Mine. Considering that the main abandoned roadway of the coal mine is 500m deep and has an effective volume of 219,000 m3. The PG9171E gas turbine and its associated compressors produced by General Electric (GE) Co., Ltd. are selected. The unit parameters are as follows: a) Calculated by gas turbine design data. The internal efficiency is 0.905, the air turbine efficiency is 88%; the combustion chamber pressure loss is 3%, and the air preheater cold and hot end pressure loss is 1% and 3% respectively; 4MPa, air turbine inlet pressure Under the design conditions of the above thermal system and gas turbine unit, the CAES power station has a total power generation of 384.77 MW, a heat generation heat consumption of 4773.35 k/kWh, and a power generation consumption of 0.65 kW.W (kW.h). In the calculation, the total power generation is 380MW; the natural gas price is 2.2 yuan/m3 according to the natural gas price of Xuzhou, which is about 1.9 yuan/kg; the low calorific value of natural gas is 40000k/kg. 7.3.1 Fixed Assets Investment and Economic Benefit Analysis CAES Power Station Cost is about At 3,500 yuan / kW7, the theoretical fixed assets investment of the power station is 1.33 billion yuan. Due to the investment in roadway construction during the construction process, the construction cost of the roadway construction is 10,000 yuan/m. The total length of the roadway is about 14552m, and the effective length is 80%, the effective roadway length is 11641m, and the roadway construction investment is 116 million yuan. Taking advantage of the roadway of the coal mine, the actual investment of the power station is 1.214 billion yuan. The unit cost of the thermal power unit is about 4,500 yuan / kW, and the investment of the thermal power unit with the same capacity is about 1.71 billion yuan. The actual investment of the power station is only 7/10 of the same capacity thermal power unit. The heat generation and power generation can be generated. Calculate the natural gas consumption of the plant for 1h operation of 4.104kg, electricity consumption 2.47x105kWh. According to Xuzhou electricity price, take the trough price of 0.276 yuan / kWh, the peak electricity price of 0.98 yuan / kWh. Then the profit of power generation 1h was 225,200 yuan. 3.2 Peaking capacity analysis When the power grid peaks, the power generation capacity is 380MW, and when the valley power consumption is 247MW, the maximum peaking capacity of the peaks and valleys is 627MW. If the average daily peak of the CAES power station is 600MW, the current grid load rate is 0.8. Left and right, it can be used for system peaking with a grid capacity of 3000MW. The peaking capacity of the whole year is as high as 2. It is equivalent to 720 times of the thermal power unit with a capacity of 300MW per year. The start and stop cost of the unit is 500,000 yuan/time. It can save 360 ​​million yuan for the society every year.
3.3 Investment Feasibility Analysis The investment construction period is 5a, the funds are in three batches, the first year is 500 million yuan, the first year is 400 million yuan, and the fourth year is 314 million yuan; the cash flow table shows the life. During the period, the project received a total cash income of 14.61 billion yuan. The cash flow statement is calculated according to the following basis: the value-added tax rate of the power industry is 17%, the proportion of equipment purchase expenses is 71.58% of the total fixed assets investment, and the value-added tax of fixed assets accounts for 10.03% of the equipment purchase cost. The interest rate of 5a and above is 7.05%; the annual fixed operating expenses (including repair costs, wages and benefits, labor insurance, housing funds, etc.) account for about 2% of the life of the fixed assets, all of the cash is deposited in the bank, and the deposit The interest rate is based on the current minimum interest rate (current interest rate) 0.5%.3.3.1 Financial internal rate of return (Fffi and) The so-called financial internal rate of return refers to the discounted value of each year's net cash flow value can be equal to zero during the entire calculation period of the project. Rate 10. Calculation formula: = (1), Q means inflow of cash, C. means outflow of cash, Q shows net cash flow in year t, indicating the number of years of calculation, 3.3.2 financial net present value (FNPV) financial net present The value is an absolute value indicator used to examine the profitability of a project and reflects the present value of the excess profit that the project can obtain in addition to the profit required by the set discount rate. Calculation formula: The engineering example of the vanadium ore section predicts the initial pressure and cycle to break the 55-distance. In the production process, it guides the judgment of the step distance of the roof pressure, so as to strengthen the support measures of the mining space in time and adjust the production schedule. , Bao 6 guardian shell female full. 7
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