Pressure packing for reciprocating piston compressor with buffer gas barrier

Abstract

In a pressure packing with a buffer gas barrier, which is supplied with buffer gas via a buffer gas supply line, a sensing line is provided, which is connected at a first end to a vent volume in the pressure packing and closed at an opposite second end of the sensing line, thereby preventing gas from flowing in the sensing line. A pressure regulator is connected to the buffer gas supply line to set the buffer gas pressure in the buffer gas supply line, and during operation of the pressure packing, the pressure in the sensing line is used as a pilot pressure for the pressure regulator to set the buffer gas pressure.

Description

[Technical field]

[0001] background The invention relates to a pressure packing for a reciprocating piston compressor, the pressure packing having a buffer gas barrier on its low pressure side and a number of sealing rings on its opposite high pressure side, a vent volume is provided in the pressure packing between the buffer gas barrier and the last sealing ring before the buffer gas barrier, a vent line is connected to the vent volume, a buffer gas volume is provided in the buffer gas barrier and is connected to a buffer gas supply line, and during operation of the pressure packing, a buffer gas having a buffer gas pressure is supplied via the buffer gas supply line into the buffer gas volume at a buffer gas pressure higher than the vent pressure in the vent volume. The invention also relates to a method for operating such a pressure packing for a reciprocating piston compressor and a reciprocating piston compressor equipped with such a pressure packing.

[0002] Reciprocating piston compressors for compressing process gases are well known and are used for various process gases in many applications. Reciprocating piston compressors comprise at least one cylinder with at least one intake valve and at least one discharge valve for the process gas exchange. In the cylinder, a piston reciprocates back and forth by the actuation of a piston rod. A pressure packing surrounds the piston rod and seals the gas in the cylinder. The pressure packing comprises a packing case consisting of a number of adjacent (in the axial direction of the packing case / piston rod) packing cups with sealing rings and / or wiper rings arranged in the cups. The piston rod is connected to a crosshead, which in turn is connected to the crank of the crankshaft. The crosshead converts the rotational movement of the crank into a reciprocating movement of the piston rod. The crankshaft is located in the crankcase. Between the crankcase and the cylinder (or the pressure packing) a spacer is often arranged in which the piston rod, and possibly the crosshead or at least a part of the crosshead, reciprocates. An additional partition packing may be arranged around the piston rod between the spacer and the crankcase. During operation of the reciprocating piston compressor, leakage of process gas always occurs through or around the pressure packing, since the pressure packing is not absolutely gas-tight. Such leakage of process gas is undesirable, not only because of the resulting loss of process gas.

[0003] With some process gases, leakage of the process gas may be a problem, particularly when toxic, hazardous, flammable or explosive process gases are used.

[0004] Any release of process gas into the compressor's surroundings is undesirable. There are even legal limitations on such releases of gas that require the avoidance of release of gas into the surroundings. This is especially true when toxic or dangerous process gases are used. In the case of flammable or explosive process gases, there is an additional risk of gas accumulation in the compressor, such as in the spacer or crankcase, which must be avoided. Gas leakage into the crankcase can also contaminate the lubricating oil in the crankcase and adversely affect the operation of the compressor. When using spaces, leakage of process gas from the cylinders first enters the spacer, rather than directly into the crankcase through the pressure packing or from its surroundings. Leakage of process gas into the crankcase can be reduced in this way, but cannot be completely avoided.

[0005] Therefore, in reciprocating piston compressors, it is a common desire to contain and collect any process gas leakage from the piston rod pressure packing and convey the leakage to a safe location away from the compressor.

[0006] To achieve this, it is already known to provide a vent line in the pressure packing, which provides a connection from a location inside the pressure packing to a location outside the pressure packing. By connecting an additional conduit to the external vent line outlet from the pressure packing, it becomes possible to direct the leakage of process gas to a controlled point outside the compressor itself. The vent line is connected to a vent volume, which is arranged, for example, in a vent cup in the pressure packing or between two adjacent sealing rings. Process gas leaking into the pressure packing is directed from the vent volume to the vent line.

[0007] However, the pressure packing vent line does not completely prevent leakage of process gas because gas leakage can occur between adjacent cups or around the pressure packing.

[0008] To further reduce the leakage of the process gas, it is also known to use a pressurized buffer gas, such as nitrogen or other inert or non-problematic gas, in the pressure packing and / or the spacer. The buffer gas pressure is set higher than the pressure of the process gas at the respective location, for example on the low pressure side of the pressure packing. The buffer gas is fed between two adjacent sealing rings of the pressure packing, forming a gas barrier for the process gas in the pressure packing. In this case, only the buffer gas exits the pressure packing. If a vent line is used in the pressure packing, the internal start of the vent line in the pressure packing is located between the sealing ring on the high pressure side of the packing and the gas barrier. In this case, the buffer gas is also removed via the vent line. In the vent line, a mixture of the buffer gas and the process gas is present. Also in the partition packing, a gas barrier may be formed using a buffer gas, reducing the risk of leakage of the process gas from the spacer to the crankcase. However, the gas barrier of the pressure packing or the partition packing does not prevent leakage of the process gas between the cups or around the packing itself. Therefore, it may also be the case that the spacer is purged with a purge gas. As purge gas, the same gas is usually used as the buffer gas. This means that the purge gas is supplied to the spacer and a mixture of the purge gas and any process gas leakage is exhausted from the spacer. The use of a purge gas supplied directly to the spacer works on the principle of diluting and sweeping out process gas leakage, rather than blocking the flow of process gas leakage based on a pressure gradient (as in the case of a buffer gas barrier). However, it is necessary to maintain an adequate pressure of the purge gas supply to ensure a reliable flow to the spacer.

[0009] It is therefore also known to use so-called purge panels, which provide the necessary buffer gas for reciprocating piston compressors. The purge panel is equipped with the necessary equipment, such as valves, flow regulators, measuring instruments, etc., required to supply the buffer gas. It is particularly important to be able to control the buffer gas pressure, which must be higher than the gas pressure of the gas to be sealed or high enough to allow purging of the spacer. Usually, the buffer gas pressure is required to be at least 1 bar higher than the gas at each location where the buffer gas is used. At certain locations, such as spacer or partition packings, the buffer gas pressure may be statically set to a certain pressure. However, in order to use buffer gas in pressure packings with vent lines, it is necessary to dynamically change the buffer gas pressure, since the pressure in the packing, and especially the pressure in the vent line, usually changes dynamically (depending on the back pressure present in the vent line, for example when connected to an incineration system for incinerating leaking process gas). The pressure in the vent line is therefore often used as a pilot pressure to control a pressure regulator in the purge panel to set the buffer gas pressure.

[0010] Often the vent line connected to the vent volume of the pressure packing is plumbed through the panel itself, and the pressure in the vent line can be used as the pilot pressure for the differential pressure regulator. It is also known to branch the pilot line from the vent line and lead the pilot line into the purge panel. However, this creates some challenges. In lubricated compressors, a gas-liquid separator for the vent line or pilot line needs to be installed between the compressor and the purge panel, which adds extra cost. Another challenge is the pressure drop in the vent line caused by the flow of gas in the line. During compressor operation, gas leakage from the pressure packing increases over time due to wear of the sealing rings in the packing. This causes the flow of gas in the vent line to increase over time, which corresponds to an increase in the pressure drop in the vent line over time. This fluctuating (increasing) pressure drop means that the purge panel reads the wrong pilot pressure from the vent line and the pressure regulator is controlled, and therefore the performance of the purge panel decreases over time. This can result in increased process gas emissions from the compressor, which must be avoided.

[0011] It is therefore an object of the present invention to provide a pressure packing for a reciprocating piston compressor with a vent volume and a buffer gas barrier that avoids the above-mentioned problems.

[0012] Summary of the Invention This object is achieved by providing a sensing line connected at a first end to a vent volume in the pressure packing and closed at an opposite second end of the sensing line, so that no gas flows in the sensing line, and a pressure regulator connected to the buffer gas supply line for setting a buffer gas pressure in the buffer gas supply line, and during operation of the pressure packing, the pressure in the sensing line is used as a pilot pressure for the pressure regulator to set the buffer gas pressure. The sensing line is completely separated from the vent line, so that any leakage of process gas is conveyed away from the pressure packing. Since the sensing line is closed at an end opposite the vent volume and separated from the vent line, no gas flows in the sensing line, so that there is no pressure drop in the sensing line due to gas flow. This ensures an accurate reading of the vent pressure, which is used as a pilot pressure for controlling the pressure regulator, and thus the buffer gas pressure for the pressure packing is set. The buffer gas pressure is preferably set a predetermined differential pressure higher than the pilot pressure (vent pressure).

[0013] In a preferred embodiment, a differential pressure control valve with a pilot inlet is used as the pressure regulator, and the sensing line is connected to the pilot pressure inlet of the differential pressure control valve.

[0014] The sensing line is advantageously located in the upper portion of the pressure packing. This, together with the fact that the sensing line is a static line with no gas flow, reduces or even eliminates the amount of lubricant that may be carried in the sensing line. Thus, a liquid-gas separator is not required in the sensing line upstream of the pressure regulator, thereby reducing the overall cost and complexity of the system.

[0015] A purge panel is used with a pressure regulator located in a gas line of the purge panel connecting a buffer gas inlet and a buffer gas outlet of the purge panel, the buffer gas outlet being connected to a buffer gas supply line, a buffer gas inlet being provided to connect a buffer gas supply source to the purge panel, and a sensing sense line inlet being located in the purge panel and connected to the sensing sense line, thereby allowing all the equipment required to supply the buffer gas to be neatly arranged.

[0016] When a purge panel with an enclosure is used, it is particularly advantageous to provide a pneumatic booster relay located outside the enclosure with a sensing line connected to the pilot port of the pneumatic booster relay, in this way it is possible to reliably prevent process gas in the sensing line from leaking into the enclosure in the event of a dangerous malfunction.

[0017] The invention will now be explained in more detail with reference to FIGS. 1 to 6, which show exemplary, schematic and non-limiting advantageous embodiments of the invention. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 shows a reciprocating piston compressor with pressure packing, a spacer, and a crankcase. [Diagram 2] FIG. 1 illustrates an embodiment of a pressure packing. [Diagram 3] FIG. 1 is a diagram of a pressure packing of the present invention with a buffer gas barrier and a sensing line connected to a vent volume. [Figure 4] FIG. 1 illustrates an embodiment of a purge panel with a pressure regulator. [Diagram 5] FIG. 13 illustrates an embodiment of a purge panel with additional equipment. [Figure 6] FIG. 1 illustrates an embodiment of a purge panel with an enclosure and a pneumatic booster relay outside the enclosure.

[0019] Detailed Description FIG. 1 shows a typical configuration of a reciprocating piston compressor 1 having one cylinder 2 arranged in a cylinder head 3. In the cylinder 2, a piston 4 reciprocates back and forth. In the example of FIG. 1, the compressor 1 is a double-acting piston compressor with two compression volumes, one on either side of the piston 4 in the cylinder 2. However, the compressor 1 may also be a single-acting piston compressor. The reciprocating piston compressor 1 of FIG. 1 has only one cylinder 2, but of course it may have any number of cylinders required. The reciprocating piston compressor 1 may also be realized as a single-stage compressor or as a multi-stage compressor. As is known, in a multi-stage compressor, the compressed gas of a cylinder is fed to another cylinder for further compression. The cylinder 2 has at least one suction valve 5 and one discharge valve 6 (shown only diagrammatically in FIG. 1) for each compression volume, with which the process gas is exchanged. Any known configuration of suction valves 5 / discharge valves 6 can be used. An inlet line connected to an intake valve 5 for supplying process gas to the compressor 1 and a discharge line connected to a discharge valve 6 for the compressed process gas are not shown in FIG. 1 for the sake of simplicity.

[0020] A crankshaft 8 having a crank 9 is arranged in the crankcase 7. The crankshaft 8 is driven by a drive (not shown in FIG. 1), for example an electric motor or an engine, and rotates about a rotation axis. A connecting rod 10 connects the crank 9 to a crosshead 11 slidably arranged in the compressor 1, for example in the crankcase 7 as shown in FIG. 1 or in another part of the compressor 1. The crosshead 11 is also connected to a first axial end of a piston rod 12, the second axially opposite end of which is connected to the piston 4. As is known, with this arrangement, the rotational movement of the crankshaft 8 is converted into a reciprocating movement of the piston rod 12 and, therefore, into a reciprocating movement of the piston 4 in the cylinder 4.

[0021] Pressure packing 14 is provided around the reciprocating piston rod 12 to seal the process gas PG in the cylinder 2 from the other components of the piston compressor 1. The pressure packing 14 may be located in the cylinder head 3 or in any other component of the piston compressor 1.

[0022] The pressure packing 14 of the reciprocating piston compressor 1 is known and comprises several packing cups 15, in which the cups 15 and sealing rings 16 are shown in lower case as 15a, 15b, 15c and 16a, 16b, 16c, only to make it possible to distinguish the different cups 15 and sealing rings 16, if necessary. In a recess 17 of the cup 15, the sealing ring 16 and / or the wiper ring are arranged, which are in contact with the piston rod 12. Any suitable sealing ring 16 or combination of sealing rings can be used as the sealing ring 16, for example radially or tangentially cut sealing rings, uncut sealing rings, etc. Such sealing rings 16 are known in various configurations and need not be described in more detail. Any known wiper ring can be used. Also a combination of the sealing ring(s) in the cup 15 with the wiper ring(s) is possible. The sealing ring 16 is the main process gas seal.

[0023] On the low pressure side LP of the pressure packing 14, i.e. the side of the packing 14 facing away from the cylinder 2 in use, a buffer gas barrier 18 is provided by providing a buffer gas volume 19 in the pressure packing 14 to which a buffer gas BG can be supplied via a buffer gas supply line 20. At least a part of the buffer gas supply line 20 may be arranged in the pressure packing 14. The buffer gas volume 19 is sealed against the other parts of the pressure packing 14, for example by additional sealing rings 21a, 21b, so that the buffer gas volume 19 may be pressurized by the pressurized buffer gas BG. The exemplary buffer gas volume 19 in FIG. 2 is realized between two adjacent buffer cups 18a, 18b of the pressure packing 14, in which in each of the buffer cups 18a, 18b a sealing ring 21a, 21b, or a combination of sealing rings, is arranged in a recess 22 of each of the buffer cups 18a, 18b. When the buffer gas volume 19 is pressurized with buffer gas BG, the sealing rings 21a, 21b are pressed against opposing axial walls of the pressure packing 14, e.g. the walls of each recess 21 or adjacent packing parts, and the piston rod 12, forming a buffer gas volume 19 therebetween. However, the buffer gas volume 19 of the pressure packing 14 may be realised in any other suitable form, such as a combination of sealing rings 21a, 21b in a single cavity buffer gas volume 19, where the sealing rings 21a, 21b prevent gas flow in both directions from the cavity.

[0024] As the buffer gas BG, an inert gas such as nitrogen can be used.

[0025] The buffer gas volume 19, or the buffer gas BG in the buffer gas volume 19, prevents (or at least reduces) leakage of the process gas PG from the high pressure side HP, e.g. the cylinder 2 side, to the low pressure side LP through the pressure packing 14. For this purpose, the buffer gas pressure p Bis set higher than the working pressure in the pressure packing 14 before the buffer gas volume 19 (in the direction of the high pressure side HP).

[0026] Between the buffer gas volume 19 and the main sealing rings 16a, 16b, 16c, a vent volume 24 is formed, which is connected to a vent line 25 of the pressure packing 14. The buffer gas volume 19 is sealed against the vent volume 24 by a sealing ring 21a of the buffer gas barrier 18, for example as shown in FIG. 2. At least a part of the vent line 25 may be arranged in the pressure packing 14. Additional sealing and / or wiper rings may be arranged between the sealing ring 21a of the buffer gas barrier 18 and the vent volume 24. The vent volume 24 is preferably formed between the last sealing ring 16c (in the direction of the high pressure side HP) of the buffer gas barrier 18 and the sealing ring 21a of the buffer gas barrier 18 facing the high pressure side HP of the pressure packing 14, as shown in FIG. 2. 2 is radially defined by an annular gap between the piston rod 12 and the inner circumferential surface of the buffer cup 18a, and axially defined between the buffer ring 21a of the buffer cup 18a and the sealing ring 16c of the packing cup 15c adjacent to the buffer gas volume 19. However, the vent volume 24 can also be realized in another way.

[0027] The vent volume 24 and vent line 25 serve to vent any leakage of process gas PG through the pressure packing 14, i.e. through the sealing rings 16a, 16b, 16c.

[0028] In some cases, the vent line 25 also discharges, for example, the lubricating oil of the cylinder 4 and / or the lubricating oil of the piston rod 12, which is transported together with the process gas PG. For this reason, the vent line 25 is often arranged in the lower part (in the direction of gravity) of the pressure packing 14, as shown in FIG. 2, which allows the lubricating oil to be recovered by gravity. As a result of the combination of the vent and discharge lines to remove the leaking process gas PG and the lubricating oil, a liquid-gas separator is usually required in the vent line 25 downstream of the compressor 1, to remove the liquid (lubricating oil) in the leaking process gas before further processing of the leaking process gas.

[0029] 2, an additional wiper ring 23 may be disposed on the pressure packing 14 on the low pressure side LP of the pressure packing 14. The wiper ring 23 serves to wipe any remaining crankcase lubricant from the piston rod 12. The wiped crankcase lubricant may be evacuated from the pressure packing 14 in any suitable known manner.

[0030] When the pressure packing 14 is used in the compressor 1 , the low pressure side LP of the pressure packing 14 is located on the crankcase 7 side, and the high pressure side HP faces the cylinder 2 .

[0031] The operating principle of the pressure packing 14 with the buffer gas barrier 18 and the vent line 25 is well known and is illustrated in FIG. 2 by the pressures occurring at different positions within the packing 14. The dynamically changing cylinder pressure p cyl acts on the cylinder side (high pressure side HP) of the pressure packing 14. This cylinder pressure p cyl is the vent pressure p in the vent line 25 in the pressure packing 14 across the primary seal rings 16a, 16b, 16c. V The manner in which this pressure drops is not important to the present invention, so the pressure drop is shown only as a dashed line in FIG. 2. The vent pressure p Vdepends on the back pressure acting in the vent line 25, i.e. the components to which the vent line 25 is connected. On the crankcase side (low pressure side LP) of the pressure packing 14, the buffer gas pressure p B acts in the buffer gas volume 19 of the buffer gas barrier 18. The buffer gas pressure p B is the vent pressure p V , preferably at least 1 bar higher, which prevents leakage of the process gas PG through the buffer gas barrier 18. Via the vent line 25, the mixture of buffer gas BG (leaking from the buffer gas barrier 18 towards the vent volume 24) and process gas PG leaking from the high pressure side HP through the pressure packing 14 towards the vent volume 24 is conveyed out of the compressor 1 to a safe location. A certain amount of buffer gas BG also flows out of the buffer gas barrier 18 to the adjacent part of the reciprocating piston compressor 1, i.e. the part adjacent to the reciprocating piston compressor 1, i.e. the part adjacent to the reciprocating piston compressor 1, which is usually at atmospheric pressure p atm The oil leaks into the crankcase 7 or the spacer 13 on which the oil acts.

[0032] In the embodiment of Figure 1, spacers 13 are also provided between the crankcase 7 and the cylinder 2 (cylinder head 3), and in the embodiment shown there are two spacers 13, 13a, also called the outbound spacer 13 adjacent to the cylinder 2 and the inbound spacer 13a adjacent to the crankcase 7. It should be noted that in the reciprocating piston compressor 1 according to the invention, any number of spacers 13 may be provided between the crankcase 7 and the cylinder 2 (cylinder head 3), and in particular no spacers, one spacer or two or more spacers may be provided.

[0033] A partition packing 30 may be interposed between the spacer 13 (13a) and the crankcase 7. Also, an intermediate packing 31 may be arranged between two adjacent spacers 13, 13a. The partition packing 30 and / or the intermediate packing 31 may be designed similarly to the pressure packing 14, i.e. with at least one cup with at least one sealing ring and / or wiper ring arranged therein.

[0034] The intermediate packing 31 and / or the partition packing 30 may be provided with an additional buffer gas barrier 18, which may be realized as described above for the buffer gas barrier 18 of the pressure packing 14. However, the intermediate packing 31 and / or the partition packing 30 usually does not have a vent line 25. Thus, the pressurized buffer gas BG supplied to the buffer gas barrier 18 of the intermediate packing 31 via the intermediate packing buffer gas line 32b (shown by a dashed line in FIG. 1) leaks to both the adjacent spacers 13, 13a, and the pressurized buffer gas BG prevents the passage of the process gas PG from the cylinder side spacer 13 to the crankcase side spacer 13a. Thus, the pressurized buffer gas BG supplied to the buffer gas barrier 18 of the partition packing 30 via the partition packing buffer gas line (not shown in FIG. 1) leaks to the crankcase 7 and the crankcase side spacer 13a.

[0035] The buffer gas pressure of the intermediate packing 31 or the partition packing 30 is usually atmospheric pressure p atm 1, preferably at least 1 bar higher than the pressure in the adjacent spacer 13, 13a or in the crankcase 7. Since the pressure in the spacer 13, 13a or in the crankcase 7 does not normally change, the buffer gas pressure can be statically set to the required value.

[0036] As shown in FIG. 1, the spacer 13 (13a) can also be purged by a buffer gas BG optionally. In this embodiment, the pressurized buffer gas BG is supplied to the spacer 13, 13a through the spacer buffer gas line 32, 32a. The mixture of the process gas PG and the buffer gas BG that accumulates in the spacer 13, 13a can be exhausted from the spacer 13, 13a through the spacer exhaust line 33, 33a and transported to a safe location. The buffer gas pressure of the buffer gas BG for purging the spacer 13, 13a is appropriately set. Since the pressure in the spacer 13, 13a does not usually change, the buffer gas pressure for purging the spacer 13, 13a can be statically set to a required value.

[0037] From the above description it is clear that buffer gas BG at different pressures may be required to operate the reciprocating piston compressor 1. According to the present invention, the reciprocating piston compressor 1 has at least a pressure packing 14 with a buffer gas barrier 18. Therefore, the expected vent pressure p V or existing vent pressure p V The buffer gas pressure p is always higher than B At least a buffer gas BG having a vent pressure p V varies dynamically over time. In such an embodiment, the buffer gas pressure p B also preferably varies dynamically over time.

[0038] As explained above, the buffer gas pressure p for the pressure packing 14 B is the vent pressure p in the pressure packing 14 V The vent pressure p must be higher than V is typically measured in the vent line 25 and is used as a pilot pressure to set the pressure regulator of the buffer gas BG. B In this case, the "setting" is the vent pressure p V Depending on the buffer gas pressure p B This means controlling

[0039] However, the pressure in the vent line 25 is affected by the flow of gas through the vent line 25 which causes a pressure drop along the vent line 25. Therefore, the pressure in the vent line 25 is sensed to obtain the buffer gas pressure p B If it is used to set (control), misreading will occur.

[0040] As is well known, the primary determinant of pressure drop is the gas velocity through the vent line 25, and pressure drop increases with increasing gas velocity. The pressure drop increases uncontrollably over time because the leakage flow through the vent line 25 increases over time due to wear of the pressure packing 14. Thus, the buffer gas pressure p B is controlled by the sensed pressure in the vent line 25, the buffer gas pressure p B decreases over time. This causes the pressure difference (p B -p V ) decreases, which can reduce the ability of the buffer gas barrier 18 in the pressure packing 14 to stop and contain the leaking process gas PG. B is the vent pressure p V , which would result in a backflow of process gas PG into the buffer gas supply line 20 and increased leakage of process gas PG through the pressure packing 14 into the spacer 13 or crankcase 7.

[0041] Therefore, according to the invention, the pressure in the vent line 25 is adjusted to the buffer gas pressure p BInstead, as shown in FIG. 3, an additional sensing line 35 is provided in the pressure packing 14. One end of the sensing line 35 is connected to the vent volume 24, which is also connected to the vent line 25. The other end of the sensing line 35 is closed, which means that there is no gas flow in the sensing line 35. Since there is no gas flow in the sensing line 35, there is no pressure drop associated with gas flow in the sensing line 35, and the vent pressure p in the vent volume 24 is not used as a pilot pressure. V A static pressure corresponding to .gtoreq.1 will develop in sensing line 35. Sensing line 35 does not branch off from vent line 25, so that the pressure in sensing line 35 is not affected by the pressure drop in vent line 25 associated with gas flow.

[0042] For example, the vent pressure p can be detected by sensing the pressure in the sensing line 35 using a pressure sensor 36. V It is possible to detect the pressure in the sensing line 35 (vent pressure p V ) corresponds to the buffer gas pressure p B If the pressure regulator 37 is used as a pilot pressure for setting (controlling) the buffer gas pressure p B is always the vent pressure p V This ensures that the temperature remains well above the

[0043] 3, a buffer gas reservoir 38 provides buffer gas BG, e.g., nitrogen, to a pressure regulator 37 that is controlled by a pilot pressure, which is the pressure in a sensing line 35 detected by a pressure sensor 36. The flow (volume flow or mass flow) of the buffer gas BG depends on the leakage of the pressure packing 14 and the buffer gas pressure p B does not affect.

[0044] A differential pressure control valve can be used as pressure regulator 37. The differential pressure control valve ensures a constant differential pressure in a line where the flow changes. The differential pressure control valve has a pilot pressure inlet, and the differential pressure control valve can set a desired differential pressure relative to the pilot pressure. In this case, the sensing line 35 may be connected to the pilot pressure inlet of the differential pressure control valve, and the vent pressure p of the sensing line 35 V is the pilot pressure for the differential pressure control valve. The sensing line 35 terminates in a differential pressure control valve, which again ensures static pressure in the sensing line 35. The differential pressure control valve is disposed in the buffer gas supply line 20 and controls the buffer gas pressure p B is the pilot pressure (vent pressure p V ) is controlled by a set pressure offset (differential pressure).

[0045] Buffer gas BG for the pressure packing 14 is preferably provided by a purge panel 40, as shown in dashed lines in FIG.

[0046] The sensing line 35 is preferably located in the upper (gravity direction) portion of the pressure packing 14. This, combined with the fact that the sensing line 35 is a static line with no gas flow, reduces or even eliminates the amount of lubricant that may be carried by the sensing line 35. Thus, a liquid-gas separator is typically not required in the sensing line 35 upstream of the purge panel 40, thereby reducing the cost of the system.

[0047] FIG. 4 shows a schematic diagram of a purge panel 40 for supplying a buffer gas BG to the pressure packing 14. The purge panel 40 may be arranged in a purge panel enclosure 48 (as shown in FIG. 4), but can also be constructed without an enclosure. In the case of the purge panel enclosure 48, a door is preferably provided that allows access to the equipment arranged in the purge panel enclosure 48. The purge panel 40 has a buffer gas inlet 41 for connecting a buffer gas BG supply line 42, which is connected, for example, to a buffer gas supply source 38. If the purge panel 40 has a purge panel enclosure 48 and a buffer gas supply source is arranged in the purge panel enclosure 48, the buffer gas inlet 41 can also be avoided.

[0048] The purge panel 40 has a sensing line inlet 43 to which the sensing line 35 is connected. The sensing line 35 extends from the sensing line inlet 43 into the purge panel 40. The end of the sensing line 35 in the purge panel 40 is closed so that no gas flow exists in the sensing line 35 when connected to the purge panel 40. The purge panel 40 has a buffer gas outlet 44 to which the buffer gas supply line 20 is connected when the purge panel 40 is in use. The buffer gas inlet 41 and the buffer gas outlet 44 are connected in the purge panel 40 by a gas line 46. The gas line 46 measures the puffer gas pressure p between the buffer gas outlet connector 44 and the buffer gas supply line 20 connected to the buffer gas outlet connector 44. B In the example of FIG. 4, a pressure regulator 37 for setting the pressure is provided, which is a differential pressure control valve.

[0049] In this embodiment, the sensing line 35 is connected to the pilot inlet 45 of the differential pressure control valve in which the sensing line 35 terminates. The pressure at the pilot inlet 45 and the outlet pressure of the differential pressure control valve (buffer gas pressure p B ) is set by a differential pressure control valve, and is preferably preset. Thus, the buffer gas pressure p Bis the pilot pressure (vent pressure p V ) by a preset differential pressure, and the vent pressure p V Follow.

[0050] If the purge panel 40 supplies buffer gas BG to one or more pressure packings 14, in each case the vent pressure p in the sensing line 35 of each pressure packing is V One or more pressure regulators 37 may be provided in the purge panel 40 under the control of the pressure regulator 37. In this case, a sensing line inlet 43 is present in each pressure regulator and each sensing line 35 is connected to the purge panel 40. A buffer gas outlet connector 44 is also present in each pressure regulator 37 and each buffer gas supply line 20 is connected to the purge panel 40.

[0051] The purge panel 40 may also be provided with additional equipment, as will be described with reference to FIG.

[0052] Buffer gas BG is supplied to the purge panel 40 via a buffer gas inlet 41, and when the purge panel 40 is in use, a buffer gas supply pipe 42, the other end of which is connected to a buffer gas supply source 38, is connected to the buffer gas inlet 41. In the purge panel 40, the buffer gas inlet 41 is connected to a gas pipe 46.

[0053] In the gas line 46, an isolation valve 50 is arranged downstream of the buffer gas inlet 41. If an operator wants to perform routine maintenance work on the purge panel 40 and isolates the purge panel 40 from the buffer gas supply via the isolation valve 50, the purge panel 40 will remain pressurized, which would pose a danger if the operator were to try to open components under pressure. Therefore, preferably, an isolation valve 50 with a downstream vent is used, which allows the panel to be automatically depressurized as soon as the isolation valve 50 is switched to the closed position. When such an isolation valve 50 is in the closed position, it blocks the gas line 46 upstream of the isolation valve 50. However, when the isolation valve 50 is in the closed position, it opens a vent port on the isolation valve 50 connected to the gas line 50 downstream of the isolation valve 50. Thus, when the isolation valve 50 is closed, the gas line 46 downstream of the isolation valve 50 is depressurized via the vent port. In the embodiment of FIG. 5, there can be no backflow of buffer gas BG from the outlet of the purge panel 40. This is because the check valve 55 is upstream of the outlet of the purge panel 40. With such a downstream vent, the isolation valve 50 with the check valve 55 at its outlet ensures operator safety in all circumstances.

[0054] The gas line 46 may be provided with a filter 52 , preferably downstream of the isolation valve 50 and upstream of the further equipment, to filter the buffer gas BG supplied to the purge panel 40 .

[0055] The inlet section of the gas line 46 may be provided with a first pressure control valve 53. The gas pressure of the buffer gas BG supplied to the purge panel 40 may vary for various reasons. Therefore, it is advantageous to set a specific gas pressure in the gas line 46 of the purge panel 40 via the first pressure control valve 53.

[0056] Downstream of the first pressure control valve 53, the gas line 46 feeds into a pressure regulator 37 which sets the desired buffer gas pressure as explained above.

[0057] In the embodiment of FIG. 5, a second gas line 46a branches off from the gas line 46 downstream of the first pressure control valve 53 and upstream of the pressure regulator 37. This second gas line 46a may be provided with a second pressure control valve 53a, which sets a desired gas pressure in the second gas line 46a. Downstream of the second pressure control valve 53a, the second gas line 46a is connected to a number of buffer gas outlets 47a, 47b of the purge panel 40, two buffer gas outlets 47a, 47b in the embodiment of FIG. 5. In these buffer gas outlets 47a, 47b, a constant buffer gas BG pressure may be set via the first pressure control valve 53 and / or the second pressure control valve 53a (if present). These buffer gas outlets 47a, 47b may be connected, for example, to the spacer buffer gas pipes 32, 32a or the intermediate packing buffer gas pipe 32b (see FIG. 1) or the partition packing buffer gas pipe, and buffer gas BG is supplied at a constant gas pressure to purge the spacers 13, 13a or to provide a buffer gas barrier 18 to the intermediate packing 31 or the partition packing 30.

[0058] However, more second gas lines 46a may be provided within the purge panel 40, with each second gas line 46a provided with its own second pressure control valve 53a. Each second gas line 46a may be connected to multiple buffer gas outlets 47a, 47b.

[0059] In the embodiment of Fig. 5, two buffer gas outlets 44, 44a are provided, for example, where the buffer gas BG is supplied to two pressure packings 14 of the reciprocating piston compressor 1. The buffer gas outlets 44, 44a are connected to pressure regulators 37, as explained in Fig. 4. In each case there may be any number of pressure regulators 37 connected to any number of buffer gas outlets 44, 44a provided in the purge panel 40.

[0060] The purge panel 40 may also include a pressure relief valve 57 connected to the gas line 46 downstream of the pressure regulator 37, as shown in FIG. 5. The pressure relief valve 57 is operable to regulate the pressure of the gas at a particular allowable buffer gas pressure p Bmax The buffer gas pressure in the gas line 46 is set to p B This allowable buffer gas pressure p Bmax , the pressure relief valve 57 opens to prevent damage to the reciprocating piston compressor 1 connected to the purge panel 40, for example damage to the pressure packing 14. If the second gas line 46a is provided in the purge panel 40, the second pressure relief valve 57 may of course be provided in the second gas line 46a. Of course, the release pressure of the second pressure relief valve 57 may be set differently compared to the other pressure relief valves 57 in the purge panel 40.

[0061] The pressure relief valve 57 may also open to an overpressure line 58 in the purge panel 40 which in turn may be connected to an overpressure outlet 59 which may be open to atmosphere. This is particularly preferred where a purge panel enclosure 48 is provided in the purge panel 40.

[0062] Additionally, several monitoring instruments may be provided at specific locations on the purge panel 40. For example, a pressure indicator 51 may be used to indicate the operating pressure at a specific location in the gas line 46 and / or the second gas line 46a. A flow indicator 56 may be used to indicate the actual flow of buffer gas through a specific portion of the gas line 46 and / or the second gas line 46a.

[0063] In the case of the purge panel enclosure 48, it is advantageous if the purge panel enclosure 48 is open or transparent in the area of ​​the monitoring equipment so that the monitoring equipment is visible from the outside. For this purpose, the door of the purge panel enclosure 48 may be partially transparent.

[0064] The purge panel 40 may be designed to provide any number of buffer gas outlets 44, 44a as required. Each buffer gas outlet 44, 44a may be connected to a separate pressure regulator 37, and the buffer gas pressure p at each buffer gas outlet 44, 44a may be controlled by a pressure regulator 37. B can be set individually. However, some of the buffer gas outlets 44, 44a may also be connected to a common pressure regulator 37 (as in FIG. 5). In addition, there may also be provided a number of second gas lines 46a connected to a number of additional buffer gas outlets 47a, 47b, where a constant buffer gas pressure p B may be set via the first pressure control valve 53 and / or the second pressure control valve 53a (if present), allowing flexibility in adapting the purge panel 40 to the requirements of a particular reciprocating piston compressor 1.

[0065] A valve may be provided upstream of a particular buffer gas outlet 44, 44a, 47a, 47b to shut off that buffer gas outlet 44, 44a, 47a, 47b when not required.

[0066] If the purge panel 40 is arranged in an enclosure 48, it is advantageous for safety reasons to avoid harmful process gas PG accumulating in the enclosure 48 in case of malfunction. During operation, the sensing line 35 is filled with process gas PG mixed with a certain amount of buffer gas BG. Theoretically, the sensing line 35 is gas-tight, but in practice, the possibility of accidental leakage in the enclosure 48 of the purge panel 40 is always present, and the possibility of a transient leakage and accumulation of process gas PG in the enclosure cannot be excluded, which is a potential danger. In order to avoid accumulation of process gas PG in the enclosure 48, a pneumatic booster relay 54 can be used. Such an arrangement is shown in FIG. 6. However, the pneumatic booster relay 54 may also be provided in other embodiments of the purge panel 40, for example in FIG. 4 or FIG. 5.

[0067] A pneumatic booster relay is a known pneumatic device that regulates the pressure of a gas flow based on a pilot pressure. According to a known embodiment, the pneumatic booster relay 54 has four ports: a supply port 54a, an outlet port 54b, a pilot port 54c, and an exhaust port 54d. When pilot pressure is applied to the pilot port 54c, the main valve assembly of the pneumatic booster relay 54 opens, allowing flow from the supply port 54a to the outlet port 54b. When the sensing assembly of the pneumatic booster relay 54 detects that the outlet pressure at the outlet port 54b is equal to the pilot pressure, the main valve moves to a rest position in which the outlet port 54b and the exhaust port 54d are blocked (not connected to any other port) and remains in this position until a change occurs in the pilot pressure or the outlet pressure. When the sensing assembly detects that the outlet pressure is higher than the pilot pressure, the exhaust port 54d opens, venting the excess pressure, for example, to an exhaust line or to the surroundings. When the sensing assembly detects that the outlet pressure is lower than the pilot pressure, the main valve opens and connects the supply port 54a to the outlet port 54b, allowing the system to recharge to the pilot pressure. In this way, the outlet pressure at the output port 54b corresponds to the pilot pressure at the pilot port 54a.

[0068] If the pneumatic booster relay 54 is located outside the enclosure 48 of the purge panel 40 and the sensing line 35 is connected to the pilot port 54c of the pneumatic booster relay 54, it can be ensured that the process gas PG does not enter the enclosure 48. This is because the pilot port 54c of the pneumatic booster relay 54 cannot be connected to the output port 54b of the pneumatic booster relay 54. The supply port 54a of the pneumatic booster relay 54 is connected to the gas line 46 of the purge panel 40, so that the buffer gas is supplied to the pneumatic booster relay 54. In this embodiment, the sensing line 35 is not directly connected to the pilot inlet 45 of the differential regulator 37, but is connected to the pilot port 54c of the pneumatic booster relay 54 and terminates there. Therefore, the pilot pressure of the pneumatic booster relay 54 is again the vent pressure p in the sensing line 35. VThis corresponds to the fact that the outlet pressure of the buffer gas at the output port 54b of the pneumatic booster relay 54 is equal to the vent pressure p V Therefore, the output port 54b of the pneumatic booster relay 54 is connected to the sensing line inlet 43 and further to the pilot inlet 45 of the differential regulator 37, which sets the pilot pressure of the pressure regulator 37. As a result, the process gas PG contained in the sensing line 35 is kept completely outside the enclosure 48, which prevents any leakage of the process gas PG into the enclosure 48 even if any component inside the enclosure 48 fails.

[0069] 6 shows an embodiment of a purge panel with a pressure regulator 37 for each buffer gas outlet 44, 44a. B may be set independently of each other by respective pressure regulators 37.

[0070] In the embodiment of FIG. 6, valves 62 are shown that can shut off certain outlets of the purge panel 40 as needed.

[0071] In a further advantageous embodiment of the purge panel 40, provisions may be provided in the purge panel 40 to allow the integration of a digital measuring device 60, such as a digital pressure transducer or a digital flow transducer. For this purpose, a specific connector 61 may be provided in a specific position of the purge panel 40, allowing the connection of such a digital measuring device 60. The use of a digital measuring device allows the integration of the purge panel 40 in a digital control of the purge panel 40 or of the reciprocating piston compressor 1.

[0072] 5 shows a pressure transducer PT connected to a connection 61 of the purge panel 40 as an example of a digital measuring device 60. The measurement signal of the pressure transducer PT may be transmitted to a control unit for further processing and may be used to monitor and / or control the functioning of the purge panel 40.

[0073] It is particularly advantageous to have all analog instruments and plumbing located at the front of the purge panel 40, with connectors for digital measurement instruments at the rear of the purge panel 40. This allows for easy and safe separation of analog and digital instruments. Additionally, the user of the purge panel 40 can decide whether or not, and what (type, manufacturer) digital measurement instruments they wish to use.

[0074] The minimum configuration of the purge panel 40 is shown in FIG. 4. All the additional equipment described with reference to FIG. 5 is optional. All the additional equipment can be used in any combination. In particular, the isolation valve 50, the filter 52, the first pressure control valve 53, the second gas line 46a with the second pressure control valve 53, the buffer gas outlets 47a, 47b, the pressure relief valve 57, the connector 61 for the digital measuring device 60, the pneumatic booster relay, the additional pressure regulator 37 with the additional buffer gas outlet 44a may be provided in the purge panel 40 independently of each other in any combination as required.

Claims

1. A pressure packing for a reciprocating piston compressor (1), comprising: a buffer gas barrier (18) on the low pressure side of the pressure packing (14) including a buffer gas volume (19); a number of seal rings (16) on the high pressure side opposite said pressure packing (14); a vent volume (24) between the buffer gas barrier (18) and a last seal ring of the plurality of seal rings (16) before the buffer gas barrier (18); a vent line (25) connected to said vent volume (24); A buffer gas supply line (20) connected to the buffer gas volume (19) of the buffer gas barrier (18), which supplies a buffer gas pressure (p Ｂ ) is supplied into the buffer gas volume (19) via the buffer gas supply line (20), and the buffer gas pressure (p Ｂ ) is the vent pressure (p) in the vent volume (24). Ｖ ) a buffer gas supply line (20) A pressure packing comprising: a sensing line (35) connected at a first end to the vent volume (24) and closed at an opposite second end of the sensing line (35) such that gas does not flow through the sensing line (35); The buffer gas pressure (p Ｂ a pressure regulator (37) connected to the buffer gas supply line (20) to set Further equipped with During operation of the pressure packing (14), the pressure regulator (37) regulates the pressure in the sensing line (35) relative to the buffer gas pressure (p Ｂ ) used as pilot pressure to set The pressure packing is characterized by:

2. 2. The pressure packing of claim 1, wherein the pressure regulator (37) is a differential pressure control valve having a pilot inlet (45), and the sensing line (35) is connected to the pilot inlet (45) of the differential pressure control valve.

3. 2. Pressure packing according to claim 1, characterized in that the sensing line (35) is arranged in an upper part of the pressure packing (14).

4. a purge panel (40) with the pressure regulator (37) disposed in a first gas line (46) of the purge panel (40) connecting a buffer gas inlet (41) and a buffer gas outlet (44) of the purge panel (40); the buffer gas outlet (44) is connected to the buffer gas supply line (20), and the buffer gas inlet (41) connects a buffer gas source (38) to the purge panel (40); a sensing line inlet (43) disposed in the purge panel (40) and connected to the sensing line (35); 2. The pressure packing of claim 1.

5. The method further comprises a purge panel (40) having an enclosure (48), the pressure regulator (37) being disposed in a first gas line (46) of the purge panel (40) connecting a buffer gas inlet (41) and a buffer gas outlet (44) of the purge panel (40), the buffer gas outlet (44) being connected to the buffer gas supply line (20), the buffer gas inlet (41) connecting a buffer gas source (38) to the purge panel (40).

2. The pressure packing of claim 1, wherein a pneumatic booster relay (54) is provided outside of the enclosure (48), the sensing line (35) is connected to a pilot port (54c) of the pneumatic booster relay (54), the first gas line (46) is connected to a supply port (54a) of the pneumatic booster relay (54), and an output port (54b) of the pneumatic booster relay (54) is connected to a sensing line inlet (43) of the purge panel (40).

6. 6. Pressure packing according to claim 4 or 5, characterized in that the pressure regulator (37) is connected to a plurality of buffer gas outlets (44, 44a) of the purge panel (40).

7. the pressure regulator (37) includes a plurality of pressure regulators connected to the first gas line (46) in the purge panel (40); a buffer gas outlet (44, 44a) and a sensing line inlet (43) provided for each of the plurality of pressure regulators; 6. The pressure packing according to claim 4 or 5.

8. 6. The pressure packing of claim 4 or 5, further comprising an isolation valve (50) with a downstream vent in the first gas line (46) downstream of the buffer gas inlet (41).

9. 6. The pressure packing of claim 4 or 5, further comprising a filter (52) in the first gas line (46) downstream of the buffer gas inlet (41).

10. 6. The pressure packing of claim 4 or 5, further comprising a first pressure control valve (53) in the first gas line (46) upstream of the pressure regulator (37).

11. at least one second gas line (46a) branching off from the first gas line (46) downstream of the first pressure control valve (53); at least one additional buffer gas outlet (47a, 47b) in the purge panel (40) connected to the at least one second gas line (46a); The pressure packing of claim 10 further comprising:

12. The pressure packing of claim 11, further comprising a second pressure control valve (53a) in the at least one second gas line (46a).

13. The pressure packing of claim 4 or 5, further comprising a pressure relief valve (57) in said purge panel (40) and connected to said first gas line (46).

14. The pressure packing of claim 11, further comprising a pressure relief valve (57) within the purge panel (40) connected to the at least one second gas line (46a).

15. A reciprocating piston compressor equipped with the pressure packing according to claim 1 or 2.

16. A method for operating a pressure packing (14) for a reciprocating piston compressor (1), the pressure packing (14) having a buffer gas barrier (18) on a low pressure side of the pressure packing (14) and a number of sealing rings (16) on an opposite high pressure side of the pressure packing (14), a vent volume (24) is provided within the pressure packing (14) between the buffer gas barrier (18) and a last sealing ring of the number of sealing rings (16) before the buffer gas barrier (18), a vent line (25) is connected to the vent volume, a buffer gas volume (19) is provided within the buffer gas barrier (18) and is connected to a buffer gas supply line (20), and a buffer gas pressure (p Ｂ Buffer gas (BG) having a vent pressure (p) in the vent volume (24) is supplied to the buffer gas volume (19) through the buffer gas supply line (20). Ｖ ) higher than the buffer gas pressure (p Ｂ ) , a sensing line (35) connected at a first end to the vent volume (24) and closed at an opposite second end of the sensing line (35) thereby preventing gas flow within the sensing line (35); The buffer gas pressure (p Ｂ a pressure regulator (37) is connected to the buffer gas supply line (20) to set The buffer gas pressure (p Ｂ using the pressure in the sensing line (35) as a pilot pressure for the pressure regulator (37) to set A method comprising:

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