JP2008038658A - Gas compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas compressor capable of miniaturization and energy saving. <P>SOLUTION: The gas compressor 1 compressing gas sucked into a compression chamber 2 by reducing volume of the compression chamber 2 is provided with a spray means spraying water into the compression chamber 2 and a control means 7 controlling spray timing and spray quantity of the spray means 6 to inhibit temperature rise of gas compressed in the compression chamber 2 by evaporation heat of water. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas compressor that compresses a gas such as air.

  Conventionally, a reciprocating air compressor that reciprocates a piston in a cylinder is known as a compressor that compresses a gas such as air.

  The reciprocating air compressor has a structure in which heat generated by adiabatic compression in the compressor main body is cooled by a cooler provided at the rear stage of the compressor main body after compression (for example, Patent Document 1). reference).

Japanese Patent Application Laid-Open No. 2000-234587

  However, in the above-described reciprocating air compressor, since the high-temperature air is cooled, the cooler becomes large, and in some cases, a larger area than the main body of the compressor may be required.

  Further, even if this cooling heat is reused, part or most of it is wasted as waste heat, causing energy waste.

  Then, the objective of this invention is providing the gas compressor which can achieve the size reduction and energy saving which solve the said subject.

  In order to achieve the above object, the present invention provides a spray for spraying water into the compression chamber in a gas compressor that compresses the gas sucked into the compression chamber by reducing the volume of the compression chamber. And a control means for controlling the spray timing and the spray amount of the spray means so as to suppress the temperature rise of the gas compressed in the compression chamber by the heat of vaporization of water.

  Preferably, the compression chamber is formed of a cylinder and a piston accommodated in the cylinder so as to be able to reciprocate.

  The compression chamber may be formed of a casing and a rotor that is rotatably accommodated in the casing.

  Preferably, the control means starts spraying of water by the spraying means when the compression stroke of the piston is 30% or more and less than 70% of the entire stroke during the compression step.

  Preferably, the control means sets the number of moles of water sprayed from the spraying means per compression step to 1/10 or less of the number of moles of gas to be compressed.

  According to the present invention, the excellent effect that the gas compressor can be reduced in size and energy can be achieved.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The gas compressor of this embodiment is used for supplying compressed air to a factory etc., for example.

  A schematic structure of a gas compressor (hereinafter referred to as an air compressor) of the present embodiment will be described with reference to FIG.

  As shown in FIG. 1, the air compressor 1 of the present embodiment compresses the gas sucked into the compression chamber 2 by reducing the volume of the compression chamber 2.

  More specifically, the air compressor 1 is a reciprocating type air compressor 1, and includes a cylinder 3, a cylinder head 34 and a piston 4 forming the compression chamber 2, and a piston for reciprocating the piston 4 up and down. The driving means 5, the spraying means 6 for spraying water into the compression chamber 2, and the spraying means 6 to suppress the temperature rise of the air compressed in the compression chamber 2 by the heat of vaporization of water. Control means 7 for controlling the spraying timing and the spraying amount.

  The cylinder 3 is formed with a cylindrical cylinder bore 31 extending vertically, and the piston 4 is slidably accommodated in the cylinder bore 31. A cylinder head 34 is attached to the top of the cylinder 3, and the cylinder bore 31 is closed from above by the cylinder head 34. The compression chamber 2 is defined by the wall surface of the upper portion of the cylinder bore 31, the upper surface of the piston 4, and the lower surface of the cylinder head 34.

  An intake port 32 for sucking air into the compression chamber 2 and an exhaust port 33 for discharging air compressed in the compression chamber 2 are connected to the compression chamber 2.

  Specifically, an intake port 32 and an exhaust port 33 respectively communicating with the cylinder bore 31 to the cylinder head 34, an intake valve 35 for opening and closing the intake port 32, and an exhaust valve 36 for opening and closing the exhaust port 33 are provided. Each is provided. The intake valve 35 may be a relief valve that opens when the pressure in the compression chamber 2 is equal to or lower than a predetermined suction pressure, and the exhaust valve 36 has a pressure in the compression chamber 2 greater than the suction pressure. A relief valve that opens when the pressure is higher than a predetermined discharge pressure is conceivable.

  The piston drive means 5 includes a crank mechanism 51 connected to the piston 4 and a drive device (not shown) such as an electric motor for operating the crank mechanism 51, and the crank mechanism 51 is operated by the drive device. As a result, the piston 4 reciprocates up and down.

  The spray means 6 communicates with a spray nozzle (high pressure water nozzle) 61 provided facing the compression chamber 2, a high pressure pump 62 for supplying high pressure water to the spray nozzle 61, and the high pressure pump 62 and the spray nozzle 61. And a valve 64 for opening and closing the supply path 63.

  The high-pressure pump 62 of this embodiment supplies high-pressure water of about several tens of MPa to the spray nozzle 61, and the spray nozzle 61 sprays high-pressure water into the compression chamber 2. Further, the spray timing and the spray amount of the spray nozzle 61 are adjusted by the opening / closing timing and opening degree of the valve 64, and the valve 64 is connected to the control means 7.

  The control means 7 is connected to a crank angle sensor (not shown) provided in the crank mechanism 51 of the piston drive means 5 or the like in order to detect the stroke of the piston 4.

  The control means 7 is connected to the valve 64 of the spray means 6 to transmit an open / close control signal.

  Next, the operation of the air compressor 1 of the present embodiment will be described.

  First, in the expansion stroke of the air compressor 1, the piston 4 is lowered by the piston driving means 5. As the piston 4 descends, the volume of the compression chamber 2 increases and the pressure in the compression chamber 2 decreases.

  At this time, when the pressure in the compression chamber 2 becomes equal to or lower than a predetermined suction pressure, the intake valve 35 is opened and air is sucked into the compression chamber 2.

  Next, in the compression step, the piston 4 is raised by the piston driving means 5 to reduce the volume in the compression chamber 2, thereby increasing the pressure in the compression chamber 2 and compressing the air.

  At this time, when the pressure in the compression chamber 2 becomes equal to or higher than a predetermined exhaust pressure (discharge pressure), the exhaust valve 36 is opened, and the compressed air is discharged from the compression chamber 2.

  In the present embodiment, water is sprayed from the spray nozzle 61 in order to suppress the temperature rise of the air compressed (adiabatic compression) in the compression chamber 2 during the compression stroke.

  Thereby, the sprayed water is vaporized and the compressed air is cooled by the heat of vaporization. As a result, the air is compressed approximately isothermally, and the energy required for compression can be saved.

  Hereinafter, this point will be described in detail with reference to Table 1, FIG. 2, and FIG. Table 1 shows the relationship between volume and absolute pressure and energy in constant temperature compression and adiabatic compression. 2 and 3, adiabatic compression is indicated by a dotted line, and constant temperature compression is indicated by a solid line.

  In this embodiment, as shown in FIG. 1, a water spray nozzle 61 is provided in the cylinder head portion 34 of the air compressor 1, and high pressure water of about several tens of MPa is sprayed in a substantially intermediate stroke of the air compression process. Yes.

  As shown in Table 1, for example, when air at 30 ° C. is adiabatically compressed until the volume becomes 70%, 50%, and 30%, the temperatures are heated to about 80 ° C., 130 ° C., and 220 ° C., respectively.

  Therefore, as shown in FIGS. 2 and 3, in the case of constant temperature compression, the absolute pressures are 0.14 MPa (see point T1), 0.20 MPa (see point T2), and 0.33 MPa (see point T3), respectively. However, in adiabatic compression, the pressure increases to 0.17 MPa (see point A1), 0.26 MPa (see point A2), and 0.54 MPa (see point A3), and a larger compressive force and compression energy are required.

  Therefore, in this embodiment, before the temperature of the adiabatic compressed air reaches 80 ° C. and the pressure reaches the exhaust pressure (for example, 0.8 MPa), high-pressure water is sprayed into the air in the cylinder 3 being compressed. To do. As a result, the sprayed water evaporates to remove the heat of vaporization from the compressed air, thereby bringing the effect of bringing the temperature and pressure of the compressed air closer to constant temperature compression.

  Next, the spraying time of the spraying means 6 will be described.

  The control means 7 of this embodiment starts spraying of water by the spraying means 6 when the compression stroke of the piston 4 is 30% or more and less than 70% of the total stroke during the compression process.

  This is because if the high-pressure water is sprayed at an early stage of 30% or less, the temperature in the cylinder 3 is low, so the sprayed water does not evaporate and adheres to the inner wall of the cylinder 3 and the compressed air cannot be cooled. Because.

  On the other hand, if the spraying of high-pressure water is delayed to 70% or more, not only the compression force and compression energy of the air in the middle of compression cannot be reduced, but also when the exhaust pressure is reached and the exhaust of the air starts, the cylinder 3 This is because the internal pressure is constant, so that there is no effect of reducing the compression force or compression energy even though there is an effect of temperature reduction by water.

  Next, the spray amount of the spray means 6 will be described.

  The control means 7 of the present embodiment sets the number of moles of water sprayed from the spraying means 6 per compression step to 1/10 or less of the number of moles of gas to be compressed.

  First, the effect of injecting water into compressed air in order to bring the compressor closer to constant temperature compression will be discussed below.

  The prerequisites are shown in Tables 2 and 3. Table 2 compares the specific heats of water and air, and Table 3 shows the heat of vaporization of water at 100 ° C.

  For example, when air at 30 ° C. is adiabatically compressed to an absolute pressure of 0.8 MPa, the temperature rises to 276 ° C., and the pressure rise stroke is fast, so 40% additional energy is required compared to constant temperature compression.

  Then, the effect at the time of cooling air with the heat of vaporization of water during compression is examined.

  Assuming that the temperature when injecting 30 moles of water at 30 ° C. into 1 mole of air is t ° C., t is the following equation (1) because the cooling heat amount of air is equal to the evaporation / heating heat amount of water.

It becomes.

  The calculation results are shown in Table 4.

  In summary, the following (1) to (3) are obtained.

  (1) When 0.12 mol of water is injected with respect to 1 mol of air, cooling close to constant temperature compression is possible, but the adverse effect of unevaporated water is considered, so about half of 0.06 mol (that is, air What is necessary is just to inject | pour 10% or less of water with respect to 1 mol number.

  (2) In this case, since about 20% of the increased energy is required for the constant temperature compression, the compression energy of the air is reduced by about 15%, and the energy saving of 10% is obtained by subtracting the compression of the steam.

(3) In the case of a 2000 Nm ³ / H compressor, the required amount of injected water is about 3 L / min.

  As described above, the spray amount of the spray means 6 is determined.

  Thus, since the air compressor 1 of this embodiment can reduce the pressure in the compression process of compressed air, the compression energy of air can be reduced and the energy saving of the air compressor 1 can be achieved.

  Further, in the present embodiment, the temperature of the compressed air that is exhausted (discharged) can be reduced, so that the compressed air cooling device can be downsized or omitted, and the air compressor 1 can be downsized.

  By the way, when relatively high pressure compressed air is required, if the air is compressed only with a single-stage compressor, the temperature of the compressed air becomes excessively high and the piston seal material of the compressor is damaged by heat. There is a problem that it ends up. Therefore, conventionally, a multi-stage compressor having a multi-stage compressor and a cooler for cooling compressed air between the compressors has been used. Therefore, the size of the compressor has been increased. On the other hand, in this embodiment, since the temperature rise of compressed air can be suppressed, high-pressure air can be provided only by the single stage air compressor 1, and compared with a multistage compressor, an air compressor 1 can be reduced in size and energy can be saved.

  In addition, this invention is not limited to the above-mentioned embodiment, Various modifications and application examples can be considered.

  For example, the air compressor is not limited to a reciprocating compressor, and a compression chamber is a screw-type air compressor formed by a casing and a rotor rotatably accommodated in the casing, or other air compressors. A machine may be used.

  In the above-described embodiment, the spray nozzle 61 is provided in the compression chamber 2. However, the present invention is not limited to this. For example, the spray nozzle 61 may be provided facing the intake port 32.

FIG. 1 is a schematic structural diagram of a gas compressor according to an embodiment of the present invention. FIG. 2 is a PV diagram of the gas compressor of the present embodiment. FIG. 3 is a diagram for explaining the relationship between the compression energy and the pressure of the gas compressor of the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas compressor 2 Compression chamber 3 Cylinder 4 Piston 6 Spraying means 7 Control means

Claims (5)

In the gas compressor that compresses the gas sucked into the compression chamber by reducing the volume of the compression chamber,
Spray means for spraying water into the compression chamber, and control for controlling the spray timing and the spray amount of the spray means so as to suppress the temperature rise of the gas compressed in the compression chamber by the heat of vaporization of water. And a gas compressor.   The gas compressor according to claim 1, wherein the compression chamber is formed of a cylinder and a piston accommodated in the cylinder so as to be reciprocally movable.   The gas compressor according to claim 1, wherein the compression chamber is formed by a casing and a rotor rotatably accommodated in the casing.   3. The gas compressor according to claim 2, wherein the control means starts spraying of water by the spray means when the compression stroke of the piston is 30% or more and less than 70% of the total stroke during the compression step. The gas according to any one of claims 1 to 4, wherein the control means sets the number of moles of water sprayed from the spray means per compression step to one tenth or less of the number of moles of gas to be compressed. Compressor.

Images