Isothermal air compression system

Abstract

The present invention provides an isothermal air compression system that can reduce compression power. [Solution] The system includes a pair of tanks A and B, which are configured to be switchable between communicating with an air tank 12 and the atmosphere, and which are capable of mixing and storing water and air; an air compression means 14 that supplies water from one of the tanks B, which is connected to the atmosphere, into the other tank A to raise the water level and isothermally compress the air in the other tank A; and a switching means 18 that, based on the completion of the discharge of compressed air from the other tank A to the air tank 12, switches the communication destination of the other tank A from the air tank 12 to the atmosphere, while switching the communication destination of one of the tanks B from the atmosphere to the air tank 12.

Description

Technical Field

[0001] The present invention relates to an isothermal air compression system.

Background Art

[0002] Conventionally, CAES (Compressed Air Energy Storage) technology for storing electrical energy as compressed air has been known (see, for example, Patent Documents 1 and 2). Air compressors used in CAES and the like are roughly classified into speed type and positive displacement type, and there are many types, but all are adiabatic compression methods. Most of the motor input power for driving the air compressor is consumed by the compression heat generated during compression. Usually, since high-temperature compressed air is difficult to use, it is cooled, the generated compression heat is discarded, and energy is wasted. Although there is a multi-stage compression method for reducing the degree of temperature rise and reducing power consumption, the disadvantage that the compressed energy cannot be effectively utilized is the same as that of the adiabatic compression method. In addition, since the compression method is mechanical, especially in the positive displacement type, part of the consumed power is wasted due to air leakage from the gap during the compression process.

[0003] On the other hand, in the industrial world, like water, electricity, and gas, compressed air is used as an industrial utility, and about 20% of the power consumption in factories is for compressed air. Since most of the power consumed for air compression is discarded into the atmosphere, reducing this waste energy is a major issue in terms of energy conservation.

[0004] In addition, the time required for one cycle of compression of the air compressor is generally short, from 1 millisecond to several milliseconds, and high-speed compression is performed. Therefore, it is difficult to cool the compression heat generated during short-time compression, and there is a problem that adiabatic compression has to be used. Also, since it is a high-speed rotating machine, maintenance work such as disassembly inspection is required as maintenance of durable life parts at regular intervals, and there is also a major issue in terms of maintenance costs.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-106548 [Patent Document 2] Japanese Patent Application Publication No. 9-149564 [Overview of the project] [Problems that the invention aims to solve]

[0006] To conserve energy, there was a need for technology to reduce the compression power required for compressed air.

[0007] The present invention has been made in view of the above, and aims to provide an isothermal air compression system that can reduce compression power. [Means for solving the problem]

[0008] To solve the above-mentioned problems and achieve the objective, the isothermal air compression system according to the present invention is characterized by comprising: a pair of tanks that are configured to be switchable between communicating with an air tank and the atmosphere and capable of mixing and storing water and air; an air compression means that supplies water from one of the tanks, which is connected to the atmosphere, into the other tank to raise the water level and isothermal compress the air in the other tank; and a switching means that, based on the completion of the discharge of compressed air from the other tank to the air tank, switches the communication destination of the other tank from the air tank to the atmosphere, while switching the communication destination of one of the tanks from the atmosphere to the air tank.

[0009] Furthermore, another isothermal air compression system according to the present invention is characterized in that, in the above-described invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and a laminated core made of thermally conductive vertical plates stacked at predetermined intervals in the horizontal direction is provided inside the tank.

[0010] Furthermore, another isothermal air compression system according to the present invention is characterized in that, in the above-described invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and the upper part of the tank is provided with an injection means for spraying water downward. [Effects of the Invention]

[0011] The isothermal air compression system according to the present invention comprises a pair of tanks capable of mixing and storing water and air, with the destination of communication being switchable between an air tank and the atmosphere; an air compression means that supplies water from one of the tanks, which is in communication with the atmosphere, into the other tank to raise the water level and isothermally compress the air in the other tank; and a switching means that, upon completion of the discharge of compressed air from the other tank to the air tank, switches the destination of the other tank from the air tank to the atmosphere, while switching the destination of the one tank from the atmosphere to the air tank. Therefore, by using an isothermal compression method, the compression power can be reduced.

[0012] Furthermore, according to another isothermal air compression system of the present invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and a laminated core made of thermally conductive vertical plates stacked at predetermined intervals in the horizontal direction is provided inside the tank. This laminated core promotes heat exchange between water and air, thereby enabling isothermal compression to be easily achieved.

[0013] Furthermore, according to another isothermal air compression system of the present invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and an injection means for spraying water downward is provided in the upper part of the tank. This means that heat exchange between water and air is promoted by the injection means, and isothermal compression can be easily achieved. [Brief explanation of the drawing]

[0014] [Figure 1]FIG. 1 is a schematic configuration diagram showing an embodiment of an isothermal air compression system according to the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing an embodiment of an isothermal air compression system according to the present invention. [Figure 3] FIG. 3 is an explanatory diagram showing an embodiment of an isothermal air compression system according to the present invention. [Figure 4] FIG. 4 is an explanatory diagram of Example 1 of the present invention, where (1) is a vertical sectional view, (2) is an enlarged view of a main part, and (3) is a horizontal sectional view. [Figure 5] FIG. 5 is an explanatory diagram of Example 2 of the present invention, where (1) is a vertical sectional view, (2) is an enlarged view of a main part, and (3) is a horizontal sectional view. [Figure 6] FIG. 6 is an explanatory diagram of Example 3 of the present invention, where (1) is a front sectional view and (2) is a side sectional view.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of an isothermal air compression system according to the present invention will be described in detail based on the drawings. Note that the present invention is not limited by this embodiment.

[0016] As shown in FIG. 1(1), an isothermal air compression system 10 according to an embodiment of the present invention includes an air tank 12 for storing compressed air, a pair of tank units A and B capable of mixing and storing water and air, and a water pump 14. In this embodiment, isothermal compression of air using only air and water is performed without CO2 generation due to combustion of fossil fuels or the like.

[0017] Tank units A and B are composed of a pair of two pressurized tanks 18 of the same structure. Each tank unit A and B may consist of one pressurized tank or three or more pressurized tanks. Tank units A and B are composed of a pair of two pressurized tanks 18 of the same structure. Each tank unit may consist of one pressurized tank or three or more pressurized tanks. A water inlet 20 and an air communication port 22 are provided at the top of the pressurized tank 18, and an inlet / outlet port 24 is provided at the bottom of the pressurized tank 18. Tank units A and B can switch the communication port 22 (communication destination) to either the air tank 12 or the atmosphere via the discharge / intake switching unit 26. In the example in Figure 1(1), tank unit A is connected to the air tank 12, and tank unit B is connected to the atmosphere.

[0018] The discharge / intake switching unit 26 includes a pipe 28 connected to the air tank 12, two branch pipes 30 branching from the pipe 28, pressure regulating valves 32 provided on each branch pipe 30, and piping units A1 and B1 connected to the ends of each branch pipe 30, respectively. Piping units A1 and B1 each have a pipe 34 communicating with the branch pipe 30, an exhaust silencer 38 provided on one side of the pipe 34 via a solenoid valve 36, and an intake check valve 42 and an intake filter 44 provided on the other side of the pipe 34 via a solenoid valve 40. The exhaust silencer 38 is provided on the exhaust port side, and the intake filter 44 is provided on the intake port side. Between the solenoid valve 40 and the intake check valve 42, a pipe 46 is connected to the pipe 34, which communicates with the communication port 22 at the top of the pressurized tank 18. A water level sensor 48 is provided between the solenoid valve 40 and the intake check valve 42 to detect the water level in the pressurized tank 18 and the piping 46. A pressure sensor (not shown) is also provided between the solenoid valves 36 and 40 in the piping 34 to detect pressure.

[0019] The switching of the flow path by the discharge / intake switching unit 26 is automatically performed by a control device (not shown) controlling the pressure regulating valve 32, the solenoid valves 36 and 40 based on the water level detection signal of the water level sensor 48. For example, during the compression stroke in the tank unit A, the solenoid valves 36 and 40 in the pipe units A1 and B1 are closed for compression. At this time, the tank unit B is in communication with the atmosphere. Then, the compression stroke is terminated by detecting the signal that the discharge pressure has reached by means of a pressure sensor. Alternatively, the compression stroke may be terminated by the water level sensor 48 detecting the signal that the water level in the pressurized tank 18 has reached a predetermined set water level. Thereafter, the solenoid valve 40 and the pressure regulating valve 32 on the pipe unit A1 side are opened to communicate the tank unit A with the air tank 12, and the discharge of compressed air into the air tank 12 is started. Thereafter, when the water level in the pipe 46 on the pipe unit A1 side rises and reaches a predetermined set water level, the water level sensor 48 outputs a water level detection signal corresponding to that set water level. Based on this output, the solenoid valve 40 on the pipe unit A1 side is closed, and the discharge stroke is terminated.

[0020] The water level sensor 48 detects the water level in the pressurized tank 18 and the water level in the pipe 46. It is preferable to use a detection method such as a laser type that can detect a variable water level for the water level sensor 48. Based on the detected water level, it is possible to detect the remaining amount of compressed air at the end of compression / discharge and the end of the discharge stroke. It is desirable to provide the water level sensor 48 above the pipe 46 so that it can detect the water level that fills the inside of the pressurized tank 18 and rises in the pipe 46. The compression stroke is terminated by detecting the signal that the discharge pressure has reached by means of a pressure sensor, and then the process proceeds to the discharge stroke to discharge as much compressed air as possible into the air tank 12. The end of the discharge stroke is detected by the water level detection signal from the water level sensor 48. For example, as shown in Fig. 1(2), the end of the discharge stroke is detected when the detected water level reaches the set detection water level set above the pipe 46. Also, as shown in Fig. 1(3), the end of the compression stroke may be detected when the detected water level reaches the set detection water level set in the pressurized tank 18.

[0021] Here, the amount of air remaining between the solenoid valve 40 in the discharge / intake switching unit 26 and the water surface in the piping 46 is compressed air that is not discharged to the air tank 12, so minimizing this amount is necessary to improve the performance of the air compressor. For this reason, it is desirable to set the position of the water surface in the piping 46 detected by the water level sensor 48 at the end of the discharge stroke as close to the solenoid valve 40 as possible. Furthermore, it is desirable to make the space between the water surface in the piping 46 and the solenoid valve 40 as small as possible. In this way, the amount of compressed air remaining between the solenoid valve 40 and the water surface in the piping 46 at the end of the discharge stroke can be reduced.

[0022] Furthermore, as water is discharged from the pressurized tank 18, the residual compressed air expands, and when it falls below atmospheric pressure, air is drawn into the pressurized tank 18 via the intake check valve 42, and the pressurized tank 18 is filled with air. The end of air filling may be determined by the detection timing of the water level detected by the water level sensor 48 in the pressurized tank 18 on the compression stroke side. In order to prevent water from remaining in the pressurized tank 18 during the intake stroke, the switching timing of tank units A and B may be adjusted according to the water level detected by the water level sensor 48 to prevent water from remaining in the pressurized tank 18 during the air filling stroke.

[0023] The water pump 14 supplies water from tank unit B (or A), which is in communication with the atmosphere, into the other tank unit A (or B). The water pump 14 is an air compression means that raises the water level in the pressurized tank 18 with the supplied water (water piston) and isothermally compresses the air in the pressurized tank 18. The compression type is positive displacement, and the compression method is reciprocating, with the metal piston used in conventional reciprocating systems being used as a water piston to compress the air. In this embodiment, by raising and lowering the water level in tank units A and B with water supplied from the water pump 14, isothermally compresses air when the water level rises and performs the function of drawing in air from the atmosphere by a pressure drop when the water level falls. Because the compression mechanism is pressurized by water, no gaps are generated and there is no loss due to leakage, and maintenance work to deal with wear and replacement of sliding members to reduce leakage is not required.

[0024] In the example shown in Figure 1(1), two water pumps 14 are arranged in parallel. The suction side of the water pumps 14 is connected to a pipe 52 that communicates with the water inlet / outlet 24 at the bottom of the pressurized tank 18 via a pipe 50, and the discharge side is connected to pipes 54A and 54B that communicate with the water inlet 20 at the top of the pressurized tank 18. Solenoid valves 56A to 56D are provided in pipe 52, and solenoid valves 58A and 58B are provided in pipes 54A and 54B, respectively. Pipe 50 is connected to pipe 52 between solenoid valves 56B and 56C. In addition, pipes 60A and 60B branch off from the discharge pipes 54A and 54B, respectively, and solenoid valves 62A and 62B are provided in these pipes 60A and 60B, respectively. Piping 60A is connected to piping 52 between solenoid valves 56A and 56B, and piping 60B is connected to piping 52 between solenoid valves 56C and 56D.

[0025] Switching of the water supply path from the water pump 14 is performed automatically by a control device (not shown) that controls solenoid valves 56A-56D, 58A, 58B, 62A, 62B, etc., based on the water level detection signal from the water level sensor 48. For example, when supplying water from tank unit B (pressurized tank 18), which is in communication with the atmosphere, to tank unit A (pressurized tank 18), solenoid valves 56C, 56D, 58A, and 58B are opened, and the other solenoid valves are closed, and water is supplied from the water inlet / outlet port 24 of tank unit B (pressurized tank 18) to the water inlet port 20 of tank unit A (pressurized tank 18) via the water pump 14. The supplied water raises the water level inside tank unit A (pressurized tank 18), and isothermally compresses the air inside tank unit A (pressurized tank 18). The compressed air, compressed to the target pressure, is discharged to the air tank 12. During the compressed air discharge stroke, the water supply from the water pump 14 may be switched from the water inlet 20 at the top of the pressurized tank 18 to the water inlet / outlet 24 at the bottom. In this case, solenoid valves 56A, 56C, 56D, and 62A should be opened, and the other solenoid valves should be closed.

[0026] In this way, once the discharge of compressed air to the air tank 12 is complete, the water flow from the water pump 14 can be switched, for example, from a flow from tank unit B to tank unit A to a flow from tank unit A to tank unit B. This makes it possible to continuously draw in and compress atmospheric air in tank units A and B.

[0027] The water supply to the pressurized tank 18 has two functions. First, it supplies water to the pressurized tank 18 and compresses the air inside by raising the water level. Second, it uses the water supplied to the pressurized tank 18 to absorb the heat of air compression through heat exchange. Therefore, the water supply to the pressurized tank 18 ensures a compression cycle time that allows for heat exchange, so that the heat generated by isothermal compression can be transferred to the water in each cycle, enabling isothermal compression within the pressurized tank 18. In addition, a cooling area for heat exchange is ensured as the water surface area. Furthermore, water with a constant flow rate is mixed with the compressed air to maintain the heat transfer coefficient required during heat exchange. By using isothermal compression, a heat exchanger to recover the heat of compression is unnecessary, and a heat transfer medium tank for heat storage is also unnecessary.

[0028] The operation and function of the above configuration will be explained. As shown in Figure 2(1), at the start of compression, tank unit A is connected to air tank 12, and tank unit B is connected to the atmosphere. The pressure regulating valve 32 on the air tank 12 side is closed. Assume that tank unit A is filled with pressurized air and tank unit B is filled with water.

[0029] As shown in Figure 2(2), when water from tank unit B is supplied to the water inlet 20 at the top of tank unit A by the water pump 14, the air inside tank unit A is isothermally compressed by the effect of rising water level (water piston action). Meanwhile, air is drawn into tank unit B.

[0030] As shown in Figure 2(3), when the compressed air pressure in tank unit A reaches the target pressure, the pressure regulating valve 32 is opened, and the discharge of compressed air from tank unit A to air tank 12 begins. During the discharge process, the water supply from water pump 14 is switched to the water inlet / outlet port 24 at the bottom of tank unit A, and after the discharge is complete, it is switched back to the water inlet port 20 at the top.

[0031] As shown in Figure 2(4), compressed air is discharged from tank unit A into air tank 12 and pressurized. Once tank unit A is filled with water, the discharge is stopped.

[0032] Next, the discharge / intake switching unit 26 switches the connection between the air tank 12 and tank units A and B to the atmosphere.

[0033] As shown in Figure 3(1), at the start of compression, tank unit B is connected to air tank 12, and tank unit A is connected to the atmosphere. The pressure regulating valve 32 on the air tank 12 side is closed. Tank unit B is filled with pressurized air, and tank unit A is filled with water.

[0034] As shown in Figure 3(2), when water from tank unit A is supplied to the water inlet 20 at the top of tank unit B by the water pump 14, the air inside tank unit B is isothermally compressed by the effect of rising water level (water piston action). Meanwhile, air is drawn into tank unit A.

[0035] As shown in Figure 3(3), when the compressed air pressure in tank unit B reaches the target pressure, the pressure regulating valve 32 is opened, and the discharge of compressed air from tank unit B to air tank 12 begins. During the discharge process, the water supply from water pump 14 is switched to the water inlet / outlet port 24 at the bottom of tank unit B, and after the discharge is completed, it is switched back to the water inlet port 20 at the top.

[0036] As shown in Figure 3(4), compressed air is discharged from tank unit B into air tank 12 and pressurized. Once tank unit B is filled with water, the discharge is stopped.

[0037] Subsequently, tank units A and B are switched, and isothermally compressed air is continuously stored in the air tank 12 through the compression cycle. In this way, during the compression stroke, the input power of the drive motor of the water pump 14 is converted into compressed air and stored.

[0038] Thus, according to this embodiment, by using an isothermal compression method, the compression power can be reduced compared to the conventional adiabatic compression method.

[0039] Incidentally, in the compression process described above, the ambient temperature air filled in the compression tank (pressurized tank 18 where air compression occurs) will rise in temperature by the amount of compression power unless it is cooled after each expansion cycle. Isothermal compression is achieved by minimizing this temperature rise. Therefore, in order to minimize the temperature difference ΔTc between the temperature of the water used as a cooling medium in the compression tank and the temperature of the air that has risen due to compression, it is necessary to maximize the amount of heat exchange Qc (heat exchange amount Qc = Uc × Ac × ΔTc) between the water and air in the compression tank. Ac is the heat exchange area and Uc is the heat transfer coefficient. The amount of heat exchange Qc is determined from the design specifications of the isothermal air compression system 10, and the temperature difference ΔTc is determined from the target expansion polytropic index. A heat exchange mechanism in the compression tank is required that satisfies a cooling capacity Uc × Ac = Qc / ΔTc suitable for the structure of the compression tank.

[0040] The absolute value of the difference in compression power between adiabatic compression and isothermal compression does not change significantly from low to high pressure, and therefore the power that can be reduced by isothermal compression also does not change significantly. To prevent the cooling capacity Uc × Ac from changing significantly even when the pressure rises due to changes in the water level in the compression tank, it is desirable to have a structure in which the heat exchange area Ac and the heat transfer coefficient Uc change with the water level. Examples of such structures include a structure in which a laminated core is built into the compression tank and a structure in which water is injected into the compression tank, but the specific details will be described later.

[0041] The amount of water injected into the compression tank, Qwc, is set to match the target isothermal compression cycle time, tc seconds. The amount of water injected, Qwc, is set to Qwc(m 3 / s)=Vc(m 3It can be calculated using ) / tc(s), where Vc is the compression tank capacity.

[0042] (Example 1) Next, Example 1 of the present invention will be described. As shown in Figure 4, Embodiment 1 of the present invention uses a vertically elongated vertical tank 18A as the pressurized tank 18. The vertical tank 18A is cylindrical with a lid and bottom. Inside the vertical tank 18A is a laminated core 72 made of thermally conductive vertical plates 70 stacked at predetermined intervals (for example, a pitch of several mm) in the horizontal direction. The vertical plates 70 are rectangular in shape and elongated in the vertical direction, and for example, aluminum plates can be used. The bottom of the laminated core 72 is fixed to the bottom inside the vertical tank 18A, and the top of the laminated core 72 is positioned close to the top end inside the vertical tank 18A. The laminated core 72 is square when viewed from above, and a roughly annular space is formed between the outer surface of the laminated core 72 and the inner wall of the vertical tank 18A when viewed from above.

[0043] The bottom of the vertical tank 18A is provided with a water inlet and outlet 24, and the top of the vertical tank 18A is provided with a water inlet 20 and a communication port 22 for air discharge and suction. The water inlet 20 at the top of the vertical tank 18A communicates with a plurality of water injection ports 76 provided on the lid 74. The water injection ports 76 are arranged in a grid pattern within a square-shaped area facing the laminated core 72. The water inlet and outlet 24 and the water inlet 20 are connected to pipes 52 and 54 (54A or 54B), respectively. Inside the vertical tank 18A is the water level WL.

[0044] During the compression stroke, water WJ is injected into the laminated core 72 from a water injection port 76 at the top of the laminated core 72, forcibly mixing the air in the space inside the laminated core 72 with the injected water WJ, and the surface area of ​​the wetted vertical plate 70 and the surface area of ​​the flowing water droplets become the heat exchange area. In this way, a large cooling area can be secured relative to the tank volume during the compression stroke. Since the water flowing down the narrow inter-plate channel entrains air, it is preferable to provide an air outlet for the flowing air in the laminated core 72, and to have a structure that allows air to circulate vertically in the space between the inner surface of the vertical tank 18A and the outer surface of the laminated core 72. To ensure air circulation even with changes in water level, it is preferable to appropriately distribute flow path holes, such as punched holes, at vertical intervals on each vertical plate 70 so that internal air can escape to the outer surface of the laminated core 72.

[0045] Thus, according to this embodiment, the laminated core 72 promotes heat exchange between water and air, making isothermal compression easily achievable.

[0046] (Example 2) Next, we will describe Example 2 of the present invention. As shown in Figure 5, Embodiment 2 of the present invention is characterized in that, in the vertical tank 18A of Embodiment 1 above, an injection nozzle 78 (injection means) is provided on the upper lid 74 instead of the water injection port 76. Note that in the example in Figure 5, a configuration in which the laminated core 72 is omitted is shown. The injection nozzle 78 injects water WJ into the vertical tank 18A and is connected to the water inlet 20 at the top of the vertical tank 18A. The injection nozzles 78 are provided at four locations at the vertices of a square when viewed from above. The laminated core 72 can also be omitted.

[0047] During the compression stroke, water WJ is injected into the vertical tank 18A from the injection nozzles 78. The injection nozzles 78 are preferably positioned to allow tangential water injection along the inner wall of the vertical tank 18A, generating a swirling flow from top to bottom along the inner surface of the vertical tank 18A. This improves the heat transfer coefficient through water surface oscillation and airflow generated by the water flow. The injection nozzles 78 may also be configured to inject directly downwards into the vertical tank 18A to ensure a sufficient water droplet area and improve the heat transfer coefficient by directly mixing with air. Multiple injection nozzles 78 may be provided at different positions on the lid 74. In this case, it is preferable that the water injection angle of each injection nozzle 78 be a narrow angle corresponding to the number of nozzles and the tank length, effectively cooling the entire space of the vertical tank 18A.

[0048] Thus, according to this embodiment, the injection nozzle 56 promotes heat exchange between water and air, making isothermal compression easily achievable.

[0049] (Example 3) Next, we will describe Example 3 of the present invention. As shown in Figure 6, Embodiment 3 of the present invention uses a horizontally elongated horizontal tank 18B as the pressurized tank 18. The horizontal tank 18B is a horizontally elongated cylindrical shape with its end faces closed by flanges 80. A water inlet and outlet 24 is provided in the longitudinal center of the bottom of the horizontal tank 18B, and an air vent 22 is provided in the longitudinal center of the top of the horizontal tank 18B. Water inlets 20 are provided at both ends of the horizontal tank 18B. Pipes 52 and 54 are connected to the water inlet and outlet 24 and the water inlet 20, respectively.

[0050] A spray pipe 82 for spraying water downwards is provided horizontally on the upper surface of the horizontal tank 18B. The spray pipe 82 is inserted and fixed into the interior of the horizontal tank 18B from flanges 80 at both the left and right ends of the horizontal tank 18B and communicates with the water inlet 20. Water nozzles 84 (spraying means) are provided at intervals along the longitudinal direction of the spray pipe 82 at the lower part of the spray pipe 82. The water nozzles 84 may be arranged in one row at the very bottom of the spray pipe 82, or in multiple rows such as two rows. Alternatively, a spray nozzle may be provided instead of water nozzles 84. In this case, the spray nozzle may be screwed into and fixed to the water nozzles 84.

[0051] During the compression stroke, spray-like water WJ is injected from the water injection port 84 or injection nozzle via the injection pipe 82 towards the horizontally elongated water surface WL at the bottom of the horizontal tank 18B, thereby promoting heat exchange between the air and water in the horizontal tank 18B.

[0052] As described above, the reduction effect of isothermal compression on compression power is lower in the low-pressure range compared to adiabatic compression, but the absolute value of the reduced power does not change significantly. Therefore, in the case of the horizontal tank 18B, it is preferable to have a structure in which the cooling area Ac and the heat transfer coefficient Uc change as the water level rises, so that the value of Uc × Ac, which is the heat exchange capacity, does not change significantly. Specifically, in the high-pressure range, the cooling area Ac gradually decreases, but it is preferable to have a structure in which the stirring effect is improved by bringing the water surface WL and the injection nozzle closer together, thereby maintaining the isothermal cooling capacity by improving the heat transfer coefficient Uc.

[0053] When prioritizing the maximization of the heat exchange area Ac, it is preferable to inject the water WJ through injection nozzles, inject the water WJ as mist droplets with an angle in the injection direction, and set the number of injection nozzles and each injection angle so that the entire air space in the horizontal tank 18B is filled with water droplets.

[0054] If maximizing the heat transfer coefficient Uc is the priority, the injection of the water WJ may be made a direct injection with low direct water resistance to match the characteristics of the horizontal tank where the distance to the water surface WL is short. By causing the injected water WJ to collide with the water surface WL with a flow velocity, mutual mixing of air and water is promoted, thereby improving the heat transfer coefficient. The amount of water WJ supplied to the horizontal tank 18B by the water pump 14 Q (L / min) is adjusted to match the structural characteristics where the distance between the injection nozzle position and the water surface WL is short. The water particle size, injection velocity, and injection angle are adjusted to match the heat exchange area A (m²) in the low-pressure region. 2 ) and the heat transfer coefficient U (kcal / m 2 It is preferable to set the head of the water pump 14 to the minimum while adhering to this condition so that the product of (°C / h) is maximized.

[0055] Thus, isothermal compression can be easily achieved with this embodiment as well.

[0056] As described above, the isothermal air compression system according to the present invention comprises a pair of tanks capable of mixing and storing water and air, with the destination of communication being switchable between an air tank and the atmosphere; an air compression means that supplies water from one of the tanks, which is in communication with the atmosphere, into the other tank to raise the water level and isothermally compress the air in the other tank; and a switching means that, based on the completion of the discharge of compressed air from the other tank to the air tank, switches the destination of the other tank from the air tank to the atmosphere, while switching the destination of one of the tanks from the atmosphere to the air tank. Therefore, by using an isothermal compression method, the compression power can be reduced.

[0057] Furthermore, according to another isothermal air compression system of the present invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and a laminated core made of thermally conductive vertical plates stacked at predetermined intervals in the horizontal direction is provided inside the tank, so that heat exchange between water and air is promoted by the laminated core, and isothermal compression can be easily achieved.

[0058] Furthermore, according to another isothermal air compression system of the present invention, the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and the upper part of the tank is provided with an injection means for spraying water downwards, so that heat exchange between water and air is promoted by the injection means, and isothermal compression can be easily achieved. [Industrial applicability]

[0059] As described above, the isothermal air compression system according to the present invention is useful for air compression systems used in CAES and the like, which store electrical energy as compressed air, and is particularly suitable for reducing compression power. [Explanation of symbols]

[0060] 10. Isothermal air compression system 12 air tanks 14. Water pump (air compression means) 18. Pressurized tank (tank) 18A Vertical Tank 18B Horizontal Tank 20 Water inlet 22 connecting ports 24 Inlet and outlet 26 Discharge / Intake Switching Section Piping for 28, 34, 50, 52, 54A, 54B, 60A, 60B 30 branch pipes 32 Pressure regulating valve 36, 40, 46, 56A~56D, 58A, 58B, 62A, 62B Solenoid valves 38 Exhaust Silencer 42 Intake check valve 44 Intake filter 48 Water level sensor 70 Vertical Plate 72 stacked core 76 Water injection port (injection means) 78. Spray nozzle (spraying means) 80 flange 82 Injection pipe 84 Water injection port (injection means) A, B Tank Unit (Tank)

Claims

1. An isothermal air compression system comprising: a pair of tanks capable of storing a mixture of water and air, with their communication destination switchable to either an air tank or the atmosphere; an air compression means for supplying water from one of the tanks, which is in communication with the atmosphere, into the other tank to raise the water level and isothermally compress the air in the other tank; and a switching means for switching the communication destination of the other tank from the air tank to the atmosphere, based on the completion of the discharge of compressed air from the other tank to the air tank, while switching the communication destination of the other tank from the atmosphere to the air tank.

2. The isothermal air compression system according to claim 1, characterized in that the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and a laminated core made of thermally conductive vertical plates stacked at predetermined intervals in the horizontal direction is provided inside the tank.

3. The isothermal air compression system according to claim 1 or 2, characterized in that the tank is a vertically elongated vertical tank or a horizontally elongated horizontal tank, and the upper part of the tank is provided with an injection means for injecting water downward.

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