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Development Status and Energy Storage Characteristics of Compressed Air Energy Storage Gas Storage Device Based on Science and Technology and Engineering Power Technology Liu Jinchao 1>2 Xu Yujie1, Chen Zongyan1, Zhang Xinjing1, Chen Haisheng1, Tan Chunqing1 (Institute of Engineering Thermophysics, Chinese Academy of Sciences\Beijing 100190; University of Chinese Academy of Sciences 2 , Beijing 100190) The status quo, including the classification of gas storage devices, the technical characteristics and application of different types of gas storage devices, and detailed analysis of the energy storage characteristics of gas storage devices. The study provides a theory for the design and selection of gas storage devices.
In order to meet the sustainable development of energy and environment, countries around the world have vigorously developed renewable energy, especially wind and solar energy have become the focus of development and utilization. E.3. However, wind energy and solar energy are intermittent. And the unstable fatal flaws, it is easy to impact on the operation mode and power quality of the main power grid during the Internet, which increases the regulation pressure of the power grid. This method is considered to be a relatively economical way of storing gas. The estimated cost of a typical structure is as low as 2 / kW * h, and the estimated cost is usually 6 ~ 10 / kW. h. This gas storage device is applied earlier. In 1978, the Huntorf power station in Germany used a dome-shaped salt cavern located 600m deep underground to store compressed air. The designed gas storage pressure was (4.8 ~ 6.6) MPa. The US McIntosh compressed air energy storage power station also uses abandoned salt caves for storage. The gas storage chamber is located at a depth of 450 m underground, and the maximum gas storage pressure can reach 7.5 MPa. 1.2. 2 The hard rock stratum structure of the mine or cave is more resistant to the compressive strength of the mine or cave than the salt rock cave structure. The high pressure capability and high safety are its outstanding advantages. The disadvantage is that the construction is difficult due to the hard rock and the construction cost is high. 50-52. The research shows that the cost of building a new hard rock structure gas storage device is about 30 KkW*h) 48, while the use of abandoned hard rock structure mines costs about For 10, it is slightly higher than the salt cave structure. Norton's compressed air energy storage project in Ohio, USA, uses compressed limestone in a waste limestone mine located 670 m underground. The cavern capacity is 9.6 gas pressure (5.5 1.2.3 Underground aquifer underground aquifer is a salt cavern Another economical way of storing gas, even areas with good geological structural characteristics, is expected to be close to or lower than the salt cavern mode M. The cost of adding additional storage capacity is relatively low, enough in the well pit. Under the conditions, the added cost is about 11/(kWMi), which is one order of magnitude lower than that of the salt cavern and two orders of magnitude lower than the hard rock formation. The main disadvantage is that the location is difficult and the gas in the mat is more gas-consuming. Although there are no commercial aquifer gas storage projects, there are already research projects or projects under construction, such as the 25 MW porous rock compressed air energy storage system in Sesta, Italy, and the IAU (Iowaassociation of municipality) in Iowa, USA. Project under construction M. The IMAU project under construction uses compressed back air to store compressed air in a porous sandstone structure at a depth of 279m underground.
1.2.4 Abandoned natural gas storage chamber or petroleum storage chamber This storage method is to renovate the existing gas storage room. The transformation cost needs to be pre-evaluated, and the investment cost is usually not high. However, there are certain safety hazards, because the protective layer gas or residual gas of the original gas storage chamber may cause burning or even explosion.
Despite the obvious cost advantages of underground gas storage devices, they face problems such as difficulty in site selection, large construction projects, long construction period and even ecological migration, which limits its wide application.
1.3 Ground gas storage device The ground gas storage device is flexible and suitable for underground gas storage devices or small compressed air storage systems. According to different structural forms, the ground gas storage device can be divided into three types: gas storage tank, cylinder group and gas storage pipeline.
1.3.1 Gas storage tanks are the most widely used ground storage devices. Currently, the commonly used structures are cylindrical and spherical. It is a typical cylindrical gas storage tank consisting of a cylinder, a spherical head, a flange, a sealing element, a base and a safety attachment. The advantage is that high-pressure gas storage and long-term gas storage can be realized. Usually, the design diameter of a single gas storage tank is less than 3m, and the design length is less than 20m. The spherical gas storage tank () is another commonly used gas storage tank, compared to the cylinder. Shaped gas storage tanks, spherical gas storage tanks have the advantages of large storage capacity of a single tank and low unit investment cost. The disadvantage is that the pressure is low. Due to the large volume of a single tank, spherical gas tanks are usually assembled at the customer's site.
1 is the tank body, 2 is the support column, 3 is the manhole, 4 is the pull rod, 5 is the ladder, 6 is the safety accessory. The spherical gas tank structure 1.3.2 The cylinder group The cylinder group is connected in series or in parallel by a large number of individual cylinders. The way it is composed. Cylinder is a kind of pressure vessel, also known as gas cylinder. It has two structures of welding and seamless. The nominal working pressure of conventional cylinder is (8~30) MPa, the nominal volume is (0.4~80)L, and it is transported in CNG. And the application of gas storage field. The cylinder components commonly used in the market are vertical and horizontal, and are fixed by special steel cylinder brackets. A complete cylinder system consists of cylinders, cylinder supports, valves, gauges and piping. It is a horizontal cylinder group, which is connected in parallel, and the connecting pipeline is made of high-pressure stainless steel. The main advantage of the cylinder group is that it is flexible and can be arranged according to the needs of the user. The disadvantage is that the number of large-capacity storage is large, which brings about complicated operation and reduced reliability.
The cylinder group form 1 is the cylinder body, 2 is the ball seal head, 3 is the safety valve interface, 4 is the manhole flange, 5 is the gas inlet, 6 is the population bolt, 7 is the base, 8 is the nameplate, 9 is the sewage pipe, 10 is the gas Export, 11 is the pressure gauge interface cylindrical gas storage tank structure 3 pipeline pipeline gas storage is the use of a number of large-diameter, high-strength structural steel pipes arranged at a certain interval to store gas. It is a kind of 35-phase Liu Jinchao, etc.: Development status and energy storage characteristics of compressed air energy storage gas storage device. The gas storage pipeline form is similar to the piping arrangement of the gas cylinder group structure. The first end of the pipeline passes through the variable diameter and the elbow and the outer part. Interface connection. The advantage of this gas storage method is that it can be stored under high pressure and large capacity, flexible in layout and convenient in construction. The steel pipe with general specifications is more economical, and if buried, it can save a lot of ground space. The disadvantage is that it is currently used less in the field of energy storage. The application of pipeline gas storage method was earlier. In the 1960s, the United States built a gas storage pipeline with a length of about 5.28km, the gas storage pressure was 6.26MPa, and the pipeline material was X60 series vanadium steel pipe. Due to the backwardness of the structural steel pipe technology at that time, the application of the gas storage pipeline was limited by technology. However, people have invested more research energy into this gas storage method fo'65'74|78.79 designed a diameter of 6 m. The gas storage pipeline with a total length of 25 km can be used for 8 GW*h compressed air energy storage power station. 80. A gas storage pipeline with a pressure greater than 8.3 MPa is designed for use in small-scale CAES power stations. At present, with the rapid development of large-diameter pipeline steel technology, the yield strength of steel pipe materials has been greatly improved, the pipe wall thickness and unit steel consumption have been reduced, and the construction cost has been continuously reduced. This type of material has attracted widespread attention. . At present, China uses X series pipeline steel to store compressed natural gas in the end of long-distance pipeline and urban gas pipeline network. It has the advantages of high strength, high toughness and low unit cost. 60,1.2 CAES gas storage device energy storage characteristics analysis The CAES system shown in the release process is: the compressed air is released from the gas storage device, and after being depressurized by the pressure reducing valve, it enters the combustion chamber to burn heat, and then enters the expander to perform work.
In this process, the internal pressure of the gas storage device gradually decreases from the initial storage pressure to the rated inlet pressure of the expander at the end of the time. When the storage pressure is lower than the rated pressure of the inlet of the expander, the gas storage device stops outputting gas. The release process ends. Therefore, the compressed air actually involved in the work of the expander is only a part of the compressed air in the gas storage device, that is, the difference between the internal energy of the compressed air at the initial moment of the release phase and the internal energy of the compressed air at the end time is finally involved in the energy conversion process.
In order to facilitate the calculation, the complex thermal process in the energy release stage is not studied in depth. The compressed gas is an ideal gas, and the gas loss at the pipeline and the valve is ignored. The temperature change during the pressure reduction expansion of the gas storage device is not considered (due to the energy release process). In the middle, there is a strong heat exchange between the compressed air and the gas storage device body and the environment, so the internal temperature change of the gas storage device is ignored, which is regarded as the isothermal expansion process), and the temperature change before and after the pressure reducing valve (the working process of the pressure reducing valve is equal) The throttling process, which has a relatively small change in relative temperature drop, and the pressure change of the compressed air combustion endothermic after the pressure reducing valve. The performance indicators of the gas storage device include the volume of the gas storage device, the gas storage capacity and the energy storage density. This paper focuses on the variation of the above performance indicators under different gas storage temperatures and gas storage pressure conditions. 2.1 The volume of the gas storage device According to the ideal gas state equation, the state parameters of the initial and final time of the gas storage device in the energy release phase are pressure, temperature and mass, and the units are MPa, K and kg respectively; the subscripts s0 and si respectively represent The initial and final moments of release are equal to Tri.
In the formula (3): Am is the compressed air mass that finally participates in the work of the expander after being depressurized by the pressure reducing valve, in units of kg. According to the mass flow rate and the release working time under the rated working condition of the expander, the calculation of Am can be given. In formula (4): m is the compressed air mass flow rate under the rated working condition of the expander, unit kg/s; t is the working time of the expander's release energy, the unit s. 2.2 The gas storage capacity refers to the standard condition of the gas storage device The actual gas storage volume under the unit N*m3. According to the law of conservation of mass, the total amount of compressed air in the gas storage device can be converted into the gas storage capacity under standard conditions.
In equation (6): Ps0 is the density under the condition of p0 and Ts. It is calculated from the ideal gas state equation.
2.3 Energy Storage Density Energy storage density is an important indicator to measure the energy storage capacity of a gas storage device. The storage energy density is calculated according to formula (7).
In equation (7): y is the energy storage density (kJ/m3); E is the available air energy (kJ) after the pressure reduction of the gas storage device through the pressure reducing valve; pressure / MPa gas storage volume with the gas storage pressure and storage The change in gas temperature is a curve of the storage energy density as a function of the gas storage pressure and the storage gas temperature. It can be seen that: 1 Under the condition of a certain storage temperature, the storage energy density increases with the increase of the gas storage pressure. 2 Under the condition of a certain gas storage pressure, the storage energy density decreases with the increase of the storage gas temperature. 3 With the increase of gas storage pressure, the influence of storage temperature on storage energy density gradually increases. Compared with the two curves of storage temperature 293K and 353K, the storage energy density at 10 MPa is about 336kJ/m3. The storage energy density at 40 MPa is about 10958kJ/m. The maximum storage density occurs when the storage temperature is 293K and the storage pressure is 40MPa. The minimum value occurs when the storage temperature is 353K and the storage pressure is 10MPa. .
From the above analysis, the storage energy density varies with the gas storage pressure and the storage gas temperature. It can be seen that the gas storage pressure and the storage gas temperature have a great influence on the performance index of the gas storage device. In contrast, the gas storage pressure has a greater impact. . For the CAES system with system parameters, increasing the gas storage pressure and lowering the gas storage temperature can significantly reduce the influence of the gas storage temperature on the gas storage capacity. The storage gas pressure is 10 MPa, for example, the gas storage temperature is 293K. When the pressure is about 215N, m3, and the gas storage pressure is 40MPa, the storage gas temperature is 293K, which is the curve of the gas storage volume with the gas storage pressure and the storage gas temperature. It can be seen that: 1 the gas storage volume decreases simultaneously with the increase of the gas storage pressure and the storage gas temperature. 2 The gas storage pressure has a great influence on the gas storage capacity. Taking the storage gas temperature of 293K as an example, when the gas storage pressure is 10 MPa, it is about 2.6 times that of 40 MPa. 3 With the increase of gas storage pressure, the volume of the storage and storage device varies with the gas storage pressure and the storage gas temperature. 2.4 Calculation of the performance of the gas storage device According to the analysis results of Sections 2.1 to 2.3, the performance index of the gas storage device is calculated and calculated. The law of change under different working conditions. The technical parameters of the CAES system are shown in Table 1.
The technical parameters of Table 1 are the curves of the volume of the gas storage device as a function of the gas storage pressure and the storage gas temperature. It can be seen that: 1 The volume of the gas storage device is greatly affected by the gas storage pressure. Under the condition that the storage temperature is constant, the volume of the gas storage device gradually decreases with the increase of the gas storage pressure. 2 In the range of gas storage pressure (10 ~ 20) MPa, the volume of the gas storage device decreases relatively quickly, and the speed decreases after 20MPa; the storage temperature is 293K, and the storage pressure is 20MPa. The volume ratio of the gas device is reduced by about 53 m3.3. Under the condition that the gas storage pressure is constant, the volume of the gas storage device increases with the increase of the gas storage temperature, but the influence degree has no large gas storage pressure. 4 With the increase of gas storage pressure, the influence of gas storage temperature on the volume of gas storage device is gradually reduced; taking the gas storage pressure of 10 MPa as an example, the volume of the gas storage device at the gas storage temperature of 353 K is about 92 m3 higher than that at 293 K. When the gas storage pressure reaches 40 MPa, the volume of the gas storage device at the gas storage temperature of 353 K is about 1 pm, 5 Jin Jinchao at 293 K, etc., etc.: The development status of the compressed air energy storage gas storage device and the volume and storage of the energy storage characteristic analysis device The energy density can solve the problem that the gas storage device has a large area and the unit storage energy is low. However, the choice of gas storage pressure should be reasonable, not the higher the better. Since the inlet pressure of the expander is greatly affected by the design and processing of the turbine equipment, it is usually not very high. If the pressure difference between the gas storage pressure and the inlet pressure of the expander is too large, it will be the overall CAES system. Performance has a large impact. Studies have shown that the greater the pressure difference between the two, the more pressure energy is lost during the energy release process, and the lower the thermal efficiency and exergy efficiency of the system. 43. Therefore, in the design calculation of the gas storage device, it is necessary to comprehensively consider the storage. The effects of gas pressure and gas storage temperature also consider the effect of the pressure difference between the gas storage pressure and the inlet pressure of the expander on the system efficiency.
3 Conclusions This paper reviews the development and application status of CAES gas storage devices, and deeply studies the energy storage characteristics of gas storage devices, and draws the following conclusions: (1) According to different storage locations, gas storage devices can be divided into underground gas storage. Installation and ground storage. Underground gas storage devices have the outstanding advantages of large storage capacity and low gas storage cost, but excessive dependence on geological conditions limits its wide application. The ground gas storage device can get rid of the limitation of geological conditions and has broad application prospects; gas device volume, gas storage capacity and energy storage density. The main influencing factors for these three indicators are gas storage pressure and gas storage temperature; gas storage device design When selecting the type, it is necessary to comprehensively consider the influence of the gas storage pressure and the storage temperature on the energy storage characteristics and the influence of the pressure difference between the gas storage pressure and the inlet pressure of the expander on the system efficiency. Increasing the gas storage pressure can improve the performance of the gas storage device, but the pressure difference between the gas storage pressure and the inlet pressure of the expander is too large, which can significantly reduce the performance of the CAES system. Therefore, it is very important to choose the gas storage pressure reasonably.
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