JP2004116330A - Reciprocating compressor and its gas leak prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent working gas from leaking out of a reciprocating compressor used in a high pressure environment. <P>SOLUTION: In a plunger type reciprocating compressor, the working gas in a compression chamber 60 formed between a plunger 12 and a cylinder 11 is compressed by reciprocating motions of the plunger. For prevention of leakage of the gas compressed in the compression chamber from an outer peripheral part of the plunger, seal gas 62 is supplied from a seal gas supply passage 61 to a rod packing seal 13 part. A gas leak prevention means 20 is disposed at an end of the plunger to prevent the seal gas from leaking to an end opposite to the compression chamber. The operation of the gas leak prevention means is stopped when the compressor is operated. When the compressor is stopped, the gas leak prevention means performs an sealing operation. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reciprocating compressor for handling combustible gas and toxic gas and a device for preventing leakage thereof, and more particularly to a reciprocating compressor suitable for an ultra-high pressure of 30 MPa or more and a device for preventing leakage thereof.
[0002]
[Prior art]
An example of a conventional piston reciprocating compressor is described in U.S. Pat. No. 3,657,973. In the compressor described in this publication, a cylinder liner is fitted coaxially with a cylinder provided at an end, and a plurality of layers are laminated in an axial gap formed by the cylinder liner and the cylinder to form a sealing member. Is housed. The piston can be moved in the axial direction through holes formed in the shaft center of each of the cylinder, the seal member, and the cylinder liner.
[0003]
An example of a sealing device used for a reciprocating compressor is described in Japanese Patent Application Laid-Open No. Hei 7-119634. In the seal device described in this publication, in order to efficiently cool the piston rod and to prevent mixing of different fluids into the working gas, the compression chamber in the cylinder and the cylinder In a state in which both are shut off, the cooling chamber surrounding the piston rod is connected to the suction flow path and the discharge flow path via the gas cooler, the flow control valve, the first and second pressure control valves, and the check valve. A cooling passage that communicates is provided.
[Patent Document 1]
US Pat. No. 3,657,973 [Patent Document 2]
Japanese Patent Application Laid-Open No. 7-119634
[Problems to be solved by the invention]
In the above-mentioned U.S. Patent, although two types of sealing members are used for sealing the piston portion of the compressor in the drawings, the details are unknown, and the details are not clear, and in the compressor for compressing combustible gas or toxic gas. There are not enough considerations for leak prevention.
[0005]
On the other hand, in the reciprocating compressor described in JP-A-7-119634, packing is formed in a plurality of stages to prevent the working gas from leaking from the outer peripheral portion of the piston rod. The point at which the working gas flows into the shaft sealing device cooling chamber is not sufficiently considered. Therefore, when the working gas is a flammable gas or a toxic gas, a complicated processing system for processing the leakage gas of the entire compressor is required.
[0006]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to prevent leakage of compressed gas to the outside of a plunger type reciprocating compressor. Another object of the present invention is to realize a sealing device for an ultrahigh-pressure reciprocating compressor with a simple configuration. Still another object of the present invention is to realize a reciprocating compressor that can prevent leakage of gas to the outside of the compressor even when a toxic gas or a flammable gas is used as a working gas. The present invention aims to achieve at least one of these objects.
[0007]
[Means for Solving the Problems]
A feature of the present invention for achieving the above object is that in a plunger-type reciprocating compressor that compresses working gas in a compression chamber formed between a plunger and a cylinder by reciprocating motion of the plunger, the gas compressed in the compression chamber is compressed. Seal gas supply means for preventing leakage from the outer periphery of the plunger is provided, and gas leakage prevention means for preventing the seal gas from leaking to the end opposite to the compression chamber is provided at the end of the plunger. Is to stop the operation of the compressor when the compressor is operating, and perform the sealing operation when the compressor is stopped.
[0008]
In this feature, a stacked rod packing is arranged adjacent to the cylinder, and a seal gas supply means is preferably provided at an intermediate portion of the rod packing.The gas leakage prevention device is fitted with the cover and the cover. It is desirable to have a movable piston and lubricating oil supply means for supplying lubricating oil to a space formed between the piston and the cover. Further, it is preferable to provide a means for returning the piston to the original position during operation of the compressor.
[0009]
Another feature of the present invention to achieve the above object is a plunger-type reciprocating compressor for compressing a working gas in a compression chamber formed between a plunger and a cylinder by reciprocating motion of the plunger. A gas leakage prevention device provided at the opposite end, wherein the seal gas supplied from the seal gas supply means for preventing the gas compressed in the compression chamber from leaking out of the compressor, when the compressor is stopped. Is to seal.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of a reciprocating compressor according to the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view of a cylinder part of a plunger compressor. The plunger type compressor pressurizes hydrogen used for the fuel cell, and the pressure reaches as high as 70 MPa. For this reason, a leak prevention device for sealing high-pressure gas and preventing leakage to the outside of the compressor is provided. FIG. 1 shows only the left side of the reciprocating compressor formed in two stages.
[0011]
When the rod-shaped plunger 12 moves in the cylinder 11 forming the compression chamber 60 in the axial direction, the working gas compressed in the compression chamber 60 located at the tip of the plunger 12 is compressed. A reciprocating force is transmitted to the plunger 12 via a crankshaft connected to a drive source (not shown), a connecting rod connected to the crankshaft, and an intermediate rod 65 connected to the connecting rod. The plunger 12 and the intermediate rod 65 are connected by a coupling part 64.
[0012]
A cylinder cover 16 is attached to the end face of the cylinder 11 so that a compression chamber 60 is formed on the end of the plunger 12 opposite to the connection end of the intermediate rod 65. The cylinder cover 16 is formed to be hollow, and the cylinder valve 50 is housed in the hollow portion. The valve cover 17 is screwed to the cylinder cover 16 so as to cover the end face of the hollow portion of the cylinder cover 16. A through screw 51 is attached to the center of the valve cover 17 to prevent the cylinder valve 50 from coming out of the machine due to the pressure of the compression chamber 60. Note that the cylinder valve 50 may be pushed by the valve cover 17 instead of the through screw 51. In this case, the cylinder valve 50 for simplifying the structure is for guiding the hydrogen gas to the compression chamber 60 and extracting the compressed hydrogen gas, and is formed on the cylinder cover 16 in synchronization with the movement of the plunger 12. The communication between the suction passage 54 and the discharge passage 55 and the compression chamber 60 is made or interrupted. That is, the hydrogen gas 53 sucked from the suction passage 54 passes through the groove formed in the inner wall of the cylinder cover 16 in an annular shape, and the first valve (not shown) and the first passage (not shown) formed in the cylinder valve 50. And is sucked into the compression chamber. An O-ring 59 is provided near the groove 58 so that the suction gas does not leak to the discharge side. The hydrogen gas compressed in the compression chamber 60 passes through a second flow path (not shown) formed in the cylinder valve 50 and a second valve, and from a groove formed in the inner wall of the cylinder cover 16 to a discharge flow path 55. Flows into. The compressed hydrogen gas 56 that has flowed out of the discharge passage 55 is sent to the suction side of the second stage compressor if the compressor is the first stage, and to the demand source if the second stage.
[0013]
By the way, the plunger 12 described in the present embodiment has a diameter of about 20 to 40 mm and a stroke of about 100 mm. As described above, since the plunger 12 reciprocates, it is necessary to prevent the leakage of the compressed gas from the compression chamber 60 to the plunger 12 side. Therefore, in the present embodiment, a plurality of rod packing seals 13 having a rod packing 13b for sealing near the plunger 12 and a packing case a for holding the rod packing 13b are laminated in the axial direction of the plunger 12. Spacers 66 and 66b are arranged at appropriate intervals between the stacked rod packing seals 13. The outer circumferences of the cylinder 11, the rod packing seal 13, and the spacers 66 and 66b are covered with a sleeve 14 composed of double cylindrical members 67a and 67b, and a compression chamber 60 is provided between the double cylindrical members 67a and 67b. A cooling passage for cooling the heat generated and transmitted to the cylinder side is formed. The flow path 61 of the seal gas 62 is formed in the spacer 66 b arranged in the middle of the stacked rod packing seal 13. As the seal gas 62, hydrogen gas sucked into the compressor is used, and its pressure is 10 to 0 MPa.
[0014]
A packing presser 13c is disposed at an end of the stacked rod packing seal 13 on the intermediate rod 65 side. An inner cover 18 is provided adjacent to the packing retainer 13c. The rod packing seal 13 and the spacers 66 and 66b are held between the packing holder 13c and the cylinder cover 16 by bolts 15 and nuts 52 arranged at a plurality of positions in the circumferential direction. A lubricating oil passage 21 is formed in the inner cover 18 to lubricate and seal the outer periphery of the plunger 12. The lubricating oil passage 21 penetrates through the packing case 13a and the spacer 66b, and opens to the outer periphery of the plunger 12.
[0015]
A cross guide 19 containing the intermediate rod 65 and having the window 63 formed therein is disposed adjacent to the inner cover 18. The cross guide 19 holds an in-cylinder gas leakage prevention device 20, which will be described in detail later. The gas leakage prevention device 20 prevents gas leakage from between the rod packing seal 13b and the plunger 12 when the compressor is stopped, and the plunger 12 penetrates a central portion thereof. The inner cover 18 and the cross guide 19 are fixed to a crankcase (not shown).
[0016]
Next, an example of the cylinder gas leakage prevention device 20 is shown in FIGS. 2 and 3. 2 and 3 are longitudinal sectional views of the gas leakage prevention device 20, FIG. 2 is a diagram before the gas leakage prevention device 20 is operated, and FIG. 3 is a diagram when the gas leakage prevention device 20 is operated. The gas leakage prevention device 20 has a cover 31 having a U-shaped cross section in which a hole through which the plunger 12 penetrates is formed in a central portion, and a hole through which the plunger penetrates in the central portion by fitting the cover 31. And a ring seal component 35 provided at the tip of the inner peripheral side of the piston 32 to seal between the piston 32, the plunger and the inner cover 18. A hydraulic cylinder 33 is formed between the front surface of the cover 31 and the rear surface of the piston 32. For the ring seal component 35, for example, rubber having elasticity is used.
[0017]
A plurality of holes are formed on a surface of the piston 32 facing the inner cover 18, and a spiral spring 36 is held in the holes. Further, in order to prevent leakage between the piston 32, the cylinder and the cover 32, O-ring grooves are formed on the inner and outer peripheral surfaces of the piston 32, and O-rings 32a and 32b are held in these grooves. An oil supply passage 34 is formed in the cover 31 to supply oil to the hydraulic cylinder 33. When the compressor stops operating, oil whose pressure has been raised to a predetermined pressure is supplied to the hydraulic cylinder 33 from an oil supply pump (not shown).
[0018]
The operation of the in-cylinder gas leakage prevention device 20 thus configured will be described below. During the operation of the compressor, hydrogen gas compressed to about 40 to 80 MPa in the compression chamber 60 leaks from the outer periphery of the plunger 12 to the intermediate rod side. However, in this state, the compression chamber 60 is compressed by the seal gas 62 at a pressure of 10 to 20 MPa blown from the flow path 61 provided in the spacer 66b and the lubricating oil 21b supplied from the lubricating oil passage 21 formed in the inner cover 18. Leakage flow from is suppressed. Therefore, there is almost no leakage of the compressed gas. A part of the seal gas 62 may flow from the spacer 66b to the intermediate rod 65 side together with the lubricating oil. However, since the gap between the rod packing seal 13 and the plunger 13 is filled with the lubricating oil, the leakage amount is small. Therefore, the load on the plunger 12 and the load on the O-rings 32a and 32b and the ring seal component 35 are reduced without operating the gas leakage prevention device 20 in the operating state of the compressor.
[0019]
On the other hand, when the compressor stops operating, the lubricating oil pump also stops, so that the compressed gas in the compression chamber 60 flows backward to the seal gas supply channel 61 against the seal gas 62, There is no risk of leaking out of the compressor. On the other hand, the seal gas 62 flowing toward the intermediate shaft 65 has no lubricating oil from the gap formed between the plunger 12 and the rod packing seal 13, and flows through the gap to the gas leakage prevention device 20.
[0020]
Therefore, in order to operate the hydraulic cylinder 33 of the gas leakage prevention device, the hydraulic pump is started and the hydraulic pressure is supplied from the oil supply passage 34 to the hydraulic cylinder 33. When hydraulic pressure is applied to a hydraulic cylinder 33 formed on the rear side of the piston 32, the piston 32 moves toward the inner cover 18 against the spring force of the spring 36. As a result, the ring seal component 35 attached to the inner peripheral end of the piston 32 closes the gap formed between the inner cover 18 and the plunger 12 (see FIG. 3). The required pressure of the hydraulic pump is a value obtained by adding the spring force of the spring 36 to the force obtained from the product of the pressure receiving area of the outer peripheral contact diameter of the ring seal part 35, the outer diameter of the plunger 12, and the gas pressure in the compressor. Should be equal to or higher than the pressure obtained by dividing by the cylinder area.
[0021]
FIG. 2 shows a state in which the compressor is operating, and no hydraulic pressure is applied to the hydraulic cylinder 33, so that the piston 32 is pressed against the cover 31 by the spring force of the spring 36. At this time, the seal component 35 returns to the original state, and does not hinder the reciprocation of the plunger 12. In this state, very little hydrogen gas may leak from between the rod packing 13 and the plunger 12 and leak to the cross guide side from the gap formed between the cover 31 and the plunger 12 via the ring seal part 35. , The amount is negligible and does not matter.
[0022]
Another example of the gas leakage prevention device 20 according to the present invention is shown in FIGS. FIG. 4 is a view before the operation of the leak prevention device, and FIG. 5 is a view at the time of operation. This embodiment is different from the above embodiment in that the piston is returned to the original position by using hydraulic pressure instead of the spring.
[0023]
In the gas leakage prevention device 20b, a hydraulic cylinder 43 is formed between the front surface of the cover 41 and the back surface of the piston 42, as in the above embodiment. A seal component 45 is held on the inner peripheral side of the piston 42 and on the inner cover 18 side. The seal component 45 has a ring seal component 45a and two O-rings 45b and 45c, and the ring seal component 45a holds the O-rings 45b and 45c. The inner diameter of the O-ring is substantially the same as the outer diameter of the plunger, and the amount of movement of the piston 42 is set such that the crushing allowance is substantially zero when the piston 42 is moving toward the cover 41. The spring used in the above embodiment may be used together. O-rings 32a and 32b prevent leakage between the piston 42 and the cylinder 43. Oil pressure is applied to the cylinder 43 from an oil supply passage 44. The inner cover 18 has a communication passage 49 communicating with a gap 48 formed between the cover 18 and the front surface of the cover 41.
[0024]
The fuel pump (not shown) is in a stopped state during the operation of the compressor, and is started when the compressor stops. Thus, oil whose pressure has been increased to a predetermined pressure is supplied to the cylinder 43 while the compressor is stopped. When hydraulic pressure is applied to the cylinder 43 from the oil supply passage 44, the piston 42 moves to the inner cover 18 side. Accordingly, the ring seal component 45a is pressed against the rear end surface of the inner cover 18. The O-ring 45c closes a gap between the plunger 12 and the piston 42. If the leakage from the contact surface between the ring seal component 45a and the inner cover 18 is almost zero, the O-ring 45b closes the gap between the ring seal component 45a and the plunger.
[0025]
FIG. 4 shows a state during the operation of the compressor, in which the rod packing seal 13 is supplied with lubricating oil from the lubricating oil passage 21 in conjunction with the operation of the compressor. Lubricating oil is also supplied between the rod packing seal 13 and the gas leakage prevention device 20 through the lubricating oil passage 22. This lubricating oil is also supplied to the sliding surface between the O-rings 45b and 45c and the plunger 12 by the differential pressure and the reciprocating motion of the plunger 12. Therefore, the contact friction resistance of the sliding surface is reduced and an oil film is formed, so that the O-ring can be prevented from being worn.
[0026]
Further, since no hydraulic pressure is applied to the inside of the cylinder 43, a gap between the front surface of the piston 42 and the inner cover 18 serves as a hydraulic cylinder, and presses the piston 42 toward the cover 41. The O-rings 45b and 45c return to the original state, and do not hinder the reciprocation of the plunger 12. The lubricating oil supplied from the lubricating oil flow path 22 passes through gaps 46 and 48 formed between the inner cover 18 and the cylinder 41 and is discharged from the lubricating oil flow paths 47 and 49 formed in the inner cover 18. Further, a very small amount of leakage gas from the rod packing seal passes through the gaps 46 and 48 between the inner cover 18 and the cylinder 41 provided at the upper portion, and is discharged through the communication paths 47 and 49 of the inner cover. A part of the lubricating oil and a part of the leak gas may leak toward the intermediate rod 65, but the amount is negligible.
[0027]
When the compressor stops, lubrication to the rod packing also stops. Then, a hydraulic pump (not shown) is started, and the pressurized oil is supplied from the lubricating oil passage 44 to the cylinder 43 as shown in FIG. As a result, the piston 42 moves toward the inner cover 18, and presses the ring seal component 45 a held on the inner peripheral side of the piston 42 against the end surface of the inner cover 18. At this time, the O-ring 45c defines a gap formed between the plunger 12 and the piston 42, and the O-ring 45b defines a gap between the ring seal component 45a and the ring seal component 45a if there is almost no leakage at the contact surface between the ring seal component 45a and the inner cover 18. Each gap formed between the plungers is closed. Therefore, leakage of hydrogen gas from inside the compressor to outside the compressor can be prevented. The contact surface on the inner cover side is preferably subjected to a surface treatment. For this purpose, the components constituting the contact surface may be separately attached to the inner cover.
[0028]
Although the above embodiment has been described by taking as an example a compressor for compressing hydrogen gas used in a fuel cell, it goes without saying that other gas may be used. Further, the discharge pressure of the compressor is set to about 80 MPa, but the present invention can be applied to a higher pressure. According to each of the above embodiments, it is possible to prevent the working gas from leaking out of the compressor, so that it is economical for a compressor used for a high start-stop frequency. Further, since the gas leakage prevention device is not operated during the operation of the compressor, there is no possibility that the plunger or the seal device is excessively added, and the reliability of the compressor can be improved.
[0029]
【The invention's effect】
According to the present invention, since the gas leakage prevention device having the hydraulic cylinder in the cross guide is provided, it is possible to prevent the working gas from leaking from the inside of the machine to the outside even when the reciprocating compressor is stopped.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a rod seal portion of an embodiment of a plunger type reciprocating compressor according to the present invention.
FIG. 2 is a longitudinal sectional view of one embodiment of a stop gas leakage prevention device used in the compressor shown in FIG. 1;
FIG. 3 is a longitudinal sectional view of the gas leakage prevention device at stoppage shown in FIG. 2, illustrating the operation of the gas leakage prevention device.
FIG. 4 is a longitudinal sectional view of another embodiment of the stop-time gas leakage prevention device used in the compressor shown in FIG. 1;
FIG. 5 is a longitudinal sectional view of the gas leakage prevention device at stoppage shown in FIG. 4, illustrating the operation of the gas leakage prevention device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... cylinder, 2 ... piston, 3 ... piston rod, 4 ... rod packing seal, 5 ... packing holder, 6 ... distance piece, 7 ... cylinder cover, 4a ..Pre-breaker box, 4b ... Pre-breaker, 4c ... Packing case, 4d ... Rod packing, 4e ... Grand cover, 4f ... Lubricating hole, 11 ... Cylinder, 12 ...・ Plunger, 13 ・ ・ ・ Rod packing seal, 13a ・ ・ ・ Packing case, 13b ・ ・ ・ Rod packing, 13c ・ ・ ・ Packing presser, 14 ・ ・ ・ Sleeve, 15 ・ ・ ・ Bolt, 16 ・ ・ ・ Cylinder cover , 17 ... Valve presser, 18 ... Inner cover, 19 ... Cross guide, 20 ... Stop gas leakage prevention device, 21 ... Lubricant oil flow path, 22 ... · Lubricating oil flow path, 31 ··· cover, 32 ··· piston, 33 ··· cylinder, 34 ··· oil supply hole, 35 ··· ring seal parts, 36 ··· spring, 41 ··· cover , 42 ... piston, 43 ... cylinder, 44 ... oil supply passage, 45 ... seal part, 45a ... ring seal part, 45b, 45c ... O-ring, 46 ... void, 47: communication passage, 48: gap, 49: communication passage.

Claims (5)

In a plunger type reciprocating compressor in which a working gas in a compression chamber formed between a plunger and a cylinder is compressed by reciprocating motion of a plunger, a seal gas supply for preventing gas compressed in the compression chamber from leaking from an outer peripheral portion of the plunger. Means are provided, and gas leakage prevention means for preventing leakage of the seal gas to the end opposite to the compression chamber is provided at the end of the plunger, and the gas leakage prevention means stops its operation when the compressor operates. A reciprocating compressor which performs a sealing operation when the compressor is stopped. 2. The reciprocating compressor according to claim 1, wherein a stacked rod packing is disposed adjacent to the cylinder, and a seal gas supply unit is provided at an intermediate portion of the rod packing. 3. The gas leakage prevention device includes a cover, a piston that is fitted and movable on the cover, and lubricating oil supply means that supplies lubricating oil to a space formed between the piston and the cover. Item 3. A reciprocating compressor according to item 1 or 2. The reciprocating compressor according to claim 3, wherein a means for returning the piston to an original position when the compressor is operated is provided on the piston. A gas leakage prevention device used in a plunger-type reciprocating compressor that compresses a working gas in a compression chamber formed between a plunger and a cylinder by reciprocating motion of the plunger, provided at an end of the plunger opposite to the compression chamber. A gas leakage preventing device for sealing a gas supplied from a sealing gas supply means for preventing a gas compressed in the compression chamber from leaking out of the compressor when the compressor is stopped.

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