High pressure gas seal

Abstract

A gas processing system includes a vessel (102) defining a cavity (106) for processing a gas. The vessel includes a process gas inlet (108) for receiving a process gas at an input pressure and a process gas outlet (110) for discharging the process gas at an output pressure. The gas processing system also includes a shaft (122) coupled to the vessel and a stepwise sealing system (114) including a plurality of seals (136) spaced along the shaft. The shaft is configured to transfer mechanical energy to or from the gas in the vessel. Each adjacent pair of seals defines a corresponding pressure space therebetween. One of the pressure spaces is an equalization pressure space (144a) in hydraulic communication with the process gas inlet via a flow line (116) such that, in operation, a pressure in the equalization pressure space is maintained at an equalization pressure relative to a pressure in the process gas inlet.

Description

Technical Field

[0001] This invention relates to sealing shafts of high-pressure gas handling equipment, such as compressors, particularly using a step-by-step sealing system. Background Technology

[0002] When it is necessary to maintain a high differential pressure, such as between the atmosphere and a high-pressure chamber into which the moving shaft extends, a tiered or multi-stage sealing system is typically employed. Effective and reliable sealing often requires a sealing system in which the pressure decreases along the shaft in each stage, or along a leak-proof ring. The compression industry strives to increase the maximum permissible operating pressure and system speed required by rising customer specifications. However, increasing the differential pressure often makes it more difficult to contain gas within the system and may also apply more stress to the relevant sealing elements, thereby increasing pressure pulsation within the system, lubricant consumption, and unwanted gas release into the atmosphere. Summary of the Invention

[0003] One aspect of the invention features a gas handling system with a container defining a cavity for handling gas and having a process gas inlet for receiving process gas at an input pressure and a process gas outlet for discharging process gas at an output pressure. A shaft is coupled to the container and configured to transfer mechanical energy to or from the gas in the container. The system has a cascading sealing system that defines an intermediate pressure space between the cavity and the atmosphere, located between adjacent seals spaced apart along the shaft. The maximum pressure in the intermediate pressure space is lower than the greater of the input pressure and the output pressure, but higher than atmospheric pressure. The term "cascading" implies that the cascading sealing system has multiple sealing members between high-pressure and low-pressure points. In many cases, such systems progressively reduce the pressure in each stage between the high-pressure and low-pressure points. Notably, the intermediate pressure space is hydraulically connected to the process gas inlet via a flow line spaced apart from the shaft. The term "hydraulic" is not intended to imply any involvement of a liquid.

[0004] In some cases, such as in a gas compressor system, the output pressure is greater than the input pressure.

[0005] In some examples, the cascading sealing system defines multiple pressure spaces between adjacent seals spaced apart along the axis, including an intermediate pressure space and a second pressure space, the second pressure space reaching a maximum pressure during operation that is lower than the maximum pressure in the intermediate pressure space but higher than atmospheric pressure.

[0006] Some embodiments also include a purge gas source hydraulically connected to the second pressure space and pressurizing the purge gas to flow from the purge gas source into the cascading sealing system along the axis away from the container. The plurality of pressure spaces may include, for example, vent pressure spaces hydraulically connected to vents for discharging at least some of the purge gas.

[0007] In some examples, the cascading sealing system has a series of four seals defining three pressure spaces. Some examples have even more seals defining discrete pressure spaces. The multiple pressure spaces may include pressure spaces in hydraulic communication with a pressurized lubricating oil source.

[0008] In some embodiments, the intermediate pressure space is directly hydraulically connected to the process gas inlet. By "directly," I mean that there are no system components between the flow path and the compressor inlet that actively perform work on the process gas by doing work on or removing work from the gas.

[0009] Preferably, for many applications, the pressure in the intermediate pressure space is maintained within 30% of the input pressure.

[0010] In many applications, the streamlines are the only inlets or outlets for entering or leaving the intermediate pressure space during operation, except along the axial surface.

[0011] In some embodiments, the container includes a cylinder in which the shaft reciprocates within the staged sealing system. For example, the container may be a compressor cylinder.

[0012] In some other embodiments, the shaft rotates relative to the container during energy transfer between the shaft and the process gas within the container, the shaft rotating within the cascading sealing system. In some such embodiments, the adjacent seals are adjacent portions of a continuous labyrinth seal, and the intermediate pressure space is the middle portion of the labyrinthine flow path through the seal.

[0013] In some examples, the flow path defines a throttling orifice, which may be adjustable and / or controllable to influence the flow along the flow path.

[0014] In some cases, the flow path includes a one-way valve that restricts flow along the flow path toward the intermediate pressure space, such as to inhibit the flow of process gas from the inlet into the cascading sealing system.

[0015] In some embodiments, each of the seals is mounted in a corresponding seal housing within a plurality of seal housings joined together along the axis. The streamlines may be partially defined by aligned apertures in the plurality of seal housings.

[0016] In some embodiments, the container, the shaft, and the cascading sealing system are components of a first gas handling stage. The gas handling system further includes a second gas handling stage having a second container, a second shaft, and a second cascading sealing system. The first and second gas handling stages are connected such that the output of the first gas handling stage is connected to the input of the second gas handling stage. The second cascading sealing system defines a second intermediate pressure space, which is hydraulically in communication with the process gas inlet of the container of the first gas handling stage via a second flow line.

[0017] Another aspect of the invention features a method for modifying a cascading sealing system having a series of seals held within a stack of seal housings aligned to receive a shaft. The method includes placing a port housing abutting a distal face of the stack of seal housings, the port housing defining a central bore sized to accommodate the shaft, and placing a port in hydraulic communication with the central bore. The port housing also accommodates an end seal configured to restrict flow along the shaft when the cascading sealing system is installed, wherein the end seal and the nearest seal in the series of seals define an intermediate pressure space in hydraulic communication with the port. During installation into a container of a gas handling system, the port is streamlined to a gas inlet of the container of the gas handling system.

[0018] In some embodiments, the port housing has two separable housing portions, including a first portion defining the central aperture and a second portion containing the end seal.

[0019] In some cases, the end seal is a labyrinth seal.

[0020] Another aspect of the invention is a method for sealing the shaft of a gas handling container having a process gas outlet and a process gas inlet, wherein the process gas outlet and the process gas inlet operate at different pressures. The method includes: positioning a plurality of seals along the shaft, the seals defining at least one intermediate pressure space between adjacent seals; and during operation of the gas handling container, directly routing process gas leaking from the gas handling container into the intermediate pressure space back to the process gas inlet of the gas handling container, the routed process gas flowing due to the pressure difference between the intermediate pressure space and the process gas inlet of the gas handling container.

[0021] This invention has particular utility in the context of gas handling systems (such as compressors) with high-pressure containers and shaft and multi-stage shaft sealing systems. In many examples, the invention is characterized by the recirculation of process gas leaking through at least one seal back to the process gas inlet of the container. This internal recirculation of the leaked process gas effectively reduces the pressure between the various seals and the pressure differential across the seals. The reduction in pressure differential reduces contact pressure and heat generation at the seals, while providing a cooling effect along the staged sealing system through gas expansion. The improvements disclosed herein also extend seal life and reduce process gas pressure pulsation and loss, as well as lubricant consumption.

[0022] Details of one or more embodiments of the subject matter of this disclosure are set forth in the accompanying drawings and description. Other features, aspects, and advantages of the subject matter will become apparent from the description, drawings, and claims. Attached Figure Description

[0023] Figure 1 This schematically illustrates a single-stage gas handling system with a progressive sealing system.

[0024] Figure 2 This is a three-dimensional view of a part of a reciprocating shaft compressor.

[0025] Figure 3 yes Figure 2 End view of the compressor section.

[0026] Figure 4 and Figure 5 They are all along Figure 3 The cross-sectional view taken by lines 4 / 5-4 / 5 in the figure shows the shaft at opposite ends of its travel.

[0027] Figure 6 It is along Figure 3 The partial cross-sectional view taken by line 6-6 in the figure.

[0028] Figure 7 It is along Figure 3 The cross-sectional view taken by line 7-7 in the figure.

[0029] Figure 8 It is along Figure 3 An enlarged cross-sectional view of the step-by-step sealing system, taken from line 8-8.

[0030] Figure 9 yes Figure 2 An exploded view of the compressor section.

[0031] Figure 10 This schematically illustrates a staged gas handling system with two compressors, each with a staged sealing system.

[0032] Figure 11 It is a cross-sectional view of a rotary step-by-step sealing system with integrated pressure balance.

[0033] Figure 12 This is a cross-sectional view of a rotary step seal system adapted for adding pressure balancing.

[0034] Figure 13 This is a cross-sectional view of a standard step-by-step sealing system for reciprocating shafts and an adapter for adding pressure balance.

[0035] Figure 14 It shows Figure 13 The components are connected together to form a tiered sealing system and adapter with a pressure-balanced sealing system.

[0036] In different figures, the same reference numerals indicate similar elements. Detailed Implementation

[0037] First refer to Figure 1The gas handling system 100 includes a compressor 102 having a container 104 defining a cavity 106 having a process gas inlet 108 and a process gas outlet 110. For example, the compressor 102 may be a positive displacement compressor (e.g., a rotary compressor such as a vane compressor, screw compressor, scroll compressor, or blade compressor, or a reciprocating compressor such as a double-acting compressor) or a dynamic compressor (e.g., a centrifugal or axial compressor). The container 104, configured to contain the process gas, is coupled in operation to a shaft extending into the compressor. A cascading sealing system 114, indicated here by a series of boxes along the shaft, suppresses process gas leakage along the shaft. The shaft transfers mechanical energy to the process gas in the container 104 (e.g., by rotation about its longitudinal axis or translation along its longitudinal axis) and extends through the cascading sealing system 114 into the cavity 106. In one example, the shaft drives a compressor wheel inside the container 104 to significantly increase the pressure at the outlet 110 relative to the pressure at the inlet 108. For example, process gas may enter process gas inlet 108 at a pressure of approximately 800 psig and be discharged via process gas outlet 110 at a pressure of approximately 1500 psig. Preferably, the compressor compression ratio is at least 1.5:1. As shown, flow path 116 diverts leaked process gas from the gas flow entering inlet 108 between the two seals of the cascading sealing system 114. As shown, flow path 116 is directly connected to the compressor inlet. In this context, "directly" means that there are no system components between the flow path and the compressor inlet that actively perform work on the process gas by doing work on or removing work from the gas. Flow path 116 may include a throttling orifice 117, which may be fixed, adjustable, or actively controlled to optimize flow along path 116 for specific operating conditions. For some applications, a one-way check valve 119 may be provided along the flow path to prevent flow from inlet 108 to the cascading sealing system.

[0038] Next, refer to Figure 2 The cylinder of compressor 102 has a housing 118 and an end plate 120, which is bolted to the housing and through which a shaft 122 extends. Compressor cylinder 102 is a linear reciprocating compressor with two inlets 108 and two outlets 110. A conduit 124 forms a flow path. Figure 1 The 116) section feeds the leaked process gas back to one of the two inlets.

[0039] like Figure 3As shown, this particular end plate 120 has four ports communicating with the compressor's staged sealing system. These ports include a pressure equalization port 126, a purge gas port 128, a lubricating oil port 130, and a vent port 132. In some examples, fewer or more ports are present.

[0040] Next, refer to Figure 4 and Figure 5 A cascading sealing system 114 is arranged around a shaft 122 and, in this example, includes five seals 136 spaced along the shaft and a pressure-cutting rod ring 138. Each seal may include multiple sealing elements or rod rings tightly stacked together on the shaft to form a series of tight sealing interfaces with the shaft. The pressure-cutting rod ring 138 is the unit seal forming the first seal of the cascading sealing system and controls leakage to regulate backflow into the cylinder during the intake stroke and to prevent damage to the ring and disengagement from the rod. The pressure cut-off also reduces the flow of gas leaving the cylinder during the exhaust stroke. As discussed below, the pressure-cutting rod ring 138 can be modified to provide optimal effective orifice relative to the expected flow back to the inlet from behind the rod ring. The term “seal” does not imply zero clearance at the shaft surface or that there is no leakage across the seal. As will be understood by those working in the field of high-pressure gas machinery, some leakage will be expected through the high-pressure differential seal and may even be necessary to avoid high friction and premature seal failure. The expansion of gas between the seal and the shaft surface can generate beneficial cooling of the shaft, resulting in lower seal wear.

[0041] The compressor cylinder inlet 108 and outlet 110 are each characterized by a one-way valve that allows flow to either enter or exit the compressor cylinder (inlet) while inhibiting flow in the opposite direction. Each valve may have multiple parallel flow orifices. The inlets and outlets operate in pairs, each pair operating in the corresponding stroke direction of the shaft. For example, during the piston's right-to-left stroke, openings will be present at different points during the stroke for the right inlet 108 and left outlet 110. Similarly, during the return stroke from left to right, openings will be present at different points during the stroke for the left inlet 108 and right outlet 110, while the right inlet and left outlet remain closed. During this return stroke from left to right, the sealed end of the cylinder will experience a pressure rise to at least the compressor outlet pressure. This high pressure will decrease progressively along the shaft, starting from the pressure cut-off ring 138 and passing through the various stages. During the right-to-left stroke, the instantaneous pressure at the pressure cut-off ring will sometimes be lower than the compressor inlet or suction pressure, and the flow in conduit 124 may be in the opposite direction toward the sealing system. Therefore, the sealing system not only needs to withstand high pressure, but must also be adapted to extreme pressure waves or cycles that may fluctuate very rapidly.

[0042] As shown in these cross-sections, the cascading sealing system comprises a plurality of sealing housings 140 stacked along an axis and disposed within bores in a housing 118. The innermost sealing housing is sealed against the face of the cylinder housing by a nose gasket 141. In some cases, the housing 118 is divided into two parts, wherein a cast iron part forms the main cylinder, while a steel end cap is bolted to the end of the cylinder to contain the cascading sealing system. Each sealing housing 140 contains a respective seal 136, wherein the outermost seal (double-acting ring) is contained within an end plate 120. As understood in the art, each seal 136 may be a stack of multiple elements, such as a sealing ring sandwiched between two other rings supporting the sealing function. The sealing housings are axially connected to the end plate 120 by a pull rod 142 screwed into the distal sealing housing containing a pressure cut-off rod ring to hold the stack of sealing housings together for transport and assembly. The pull rod 142 also provides an alignment function. The sealing housings have alignment pathways that connect the ports of the end plate to the specific spaces between the seals. For example, these cross-sections show that the lubricating oil port 130 communicates with the space between the second and third seals along the shaft, allowing lubricating oil introduced through port 130 to reach the shaft surface between those two seals and lubricate at least some of the sealing interfaces of the sealing system. It should be noted that a blind passage, not communicating with the lubricating oil port, exists from left to right in the third seal housing. This is useless and is a result of designing the same seal housing for multiple seal housings in the assembly. Figure 6 As can be seen, the vent port 132 communicates with the space between the two outermost seals and is used to collect any residual process gas that may have leaked through the first four seals, so that it can be safely collected or destroyed without reaching the atmosphere.

[0043] Next, refer to Figure 7 and Figure 8The cascading sealing system defines a pressure space along the shaft surface, defined by various seals. Moving from the high-pressure end of the sealing system towards the atmospheric pressure end, high-pressure process gas leaking through the pressure cut-off ring first reaches an intermediate pressure space 144a between the pressure cut-off ring 138 and the first seal 136a. This intermediate pressure space 144a is composed of three stacked seal elements or rings 146. It is this pressure space 144a, which is connected to the pressure balance port 126, that feeds some of the leaked process gas into this first space back to the low-pressure inlet of the compressor. This transfer of gas from pressure space 144a back to the compressor inlet at, for example, 800 psig can result in an operating pressure of only 800 psig within space 144a. In other words, there may be a pressure difference of approximately 700 psig across the first seal (pressure cut-off ring 138), or between 40% and 60% of the total pressure difference across the cascading sealing system. Process gas leaking from intermediate pressure space 144a through seal 136a enters pressure space 144b at a pressure of, for example, about 600 psig. Further leakage through seal 136b reaches pressure space 144c, which may be at a pressure of, for example, about 500 psig. As shown in these cross-sectional views, purge gas port 128 communicates with pressure space 144c, the same space with which the lubricating oil port communicates. Therefore, in operation, the cascading sealing system defines a series of pressure spaces along the shaft at progressively decreasing pressures, where each seal creates a differential pressure between two pressure spaces. The amount of operational leakage through the seal and the pressure differential across the seal are interrelated. Generally, the higher the pressure differential across the seal, the greater the operational friction of the seal and the greater the heat generation at the seal. As noted above, the pressure balance at pressure space 144a, achieved via pressure balance port 126, creates a pressure profile of 1500-800-600-500-200-50-0 psig along the cascading sealing system. Without this pressure balance, a pressure profile under similar operating conditions could be 1500-1200-1000-600-250-50-0 psig. The pressure balance provided via pressure balance port 126 also reduces pressure pulsations within the sealing system.

[0044] In some cases, purge gas (e.g., an inert gas such as nitrogen) is introduced into pressure space 144c at a pressure higher than that in pressure space 144b, so that any leakage at seal 136b is redirected toward the compressor. In such cases, the pressure profile may be 1500-800-600-620-400-200-0 psig, and the gas transferred back to the compressor inlet may be a mixture of process gas and purge gas. In some cases, the purge gas port is omitted. In some cases, both the purge gas port and the vent are omitted.

[0045] As in Figure 8 As best seen in the diagram, the hydraulic communication between the pressure balance port 126 and the space 144a (exposed to the shaft surface) is via an aligned channel 148 in the stacked seal housing 140, leading to a recess 150 behind the seal 136a. This recess opens into the pressure space at the leading edge of the seal. The recess and the aligned channel 148 form a flow path ( Figure 1 The portion of pressure space 116) returning to the compressor inlet. The flow returning from pressure space 144a to the compressor inlet can be passively controlled by an orifice along the flow path, or actively controlled by a valve controlled according to a pressure signal, to maintain the desired operating pressure in pressure space 144a. In such a case, pressure space 144a will be at a slightly higher pressure than the compressor inlet, but still at a lower pressure than without any pressure balancing. It should be noted that although pressure balancing port 126 is shown communicating with pressure space 144a between pressure cut-off ring 138 and seal 136a, it may alternatively communicate with pressure space 144b between seal 136a and seal 136b, in which case the pressure profile may be 1500-1200-800-600-400-200-0 psig.

[0046] Next, refer to Figure 9 The end plate 120 and its connected bundle of sealing housings 140, aligned and held together by the pull rod 142, are inserted into the hole of the compressor housing 118 and held in place by housing bolts 152.

[0047] Reference Figure 10 For some applications, compressors 102 can be connected in series to generate higher operating pressures. In this example, the staged compression system 154 consists of two compressors 102 connected in series, such that the output 110a of the first compression stage supplies the input 108b of the second stage. The first compression stage is as discussed above, wherein flow path 116a feeds gas from a designated space between the seals in the first staged sealing system back to the compressor inlet 108a. In system 154, flow path 116b also feeds gas from a designated space between the seals in the second staged sealing system to the inlet 108a of the first stage compressor. Considering that the pressure at output 110b is significantly higher than the pressure at output 110a, path 116b can be throttled if necessary to provide the desired pressure profile for the second compression stage.

[0048] The aforementioned system has been described for a reciprocating compressor in which the shaft power performs work on the process gas to generate a high-pressure gas flow that can be used elsewhere in the system. The same sealing principle can be applied to linear reciprocating gas engines that use high-pressure gas flow to drive the shaft back and forth in a reciprocating manner.

[0049] The same pressure balance principle can also be used in rotary shaft seal systems. (See reference...) Figure 11 A rotary step-by-step shaft sealing system 160 is employed to seal a rotating shaft 162 extending from a high-pressure vessel (not shown), wherein the left end of the sealing system is exposed to the high-pressure vessel pressure 164. At the high-pressure end of the sealing system, a labyrinth seal 166 engages at multiple points along its length, thereby effectively reducing the pressure step-by-step along the width of the stop ring between the high-pressure vessel pressure and the first pressure space 168. A first-stage sliding seal interface 170 separates the pressure space 168 from the second pressure space 172. A second-stage sliding seal interface 174 separates the pressure space 172 from the third pressure space 176, which is exposed to the shaft seal 178 at the low-pressure end of the sealing system. A purge gas port 180 allows pressurized purge gas (such as nitrogen) to be delivered to the first pressure space 168, while a vent port 182 allows a mixture of leaked process gas and purge gas to be removed from the system for collection or disposal / destruction. An optional secondary vent port 184 allows residual gas to be discharged from pressure space 176. As discussed above, pressure equalization is provided by connecting the equalization pressure port 186 to the low-pressure (input) side of the compressor. Such a connection effectively increases the pressure drop along the labyrinth seal, reducing the pressure in pressure space 168, thereby reducing the pressure difference that must be maintained by the sliding seal interfaces 170 and 174.

[0050] In the example above, the pressure balancing port and associated channels have been integrated into the sealing system. However, by providing appropriate retrofit hardware, the principles discussed above can be applied to existing staged sealing systems. For example, Figure 12The system shown includes a typical rotary shaft-mounted step-by-step sealing system 188 and a pressure balancing adapter 190, which is bolted or otherwise attached to the high-pressure side of the sealing system about a shaft 162. The pressure balancing adapter 190 includes an adapter housing 192 configured to be mechanically secured to an existing sealing system housing and includes a pressure-cutting rod ring 138 that defines a pressure balancing port. In the example shown, the adapter housing is a stack of two plates, one defining the pressure balancing port and the other housing the rod ring. When the adapter is installed into a pre-existing sealing system, a new pressure space 194 is defined between the pressure-cutting rod ring 138 and the labyrinth seal 166. Therefore, the pressure in the pressure space 194 is regulated by the pressure balancing system, thereby reducing the pressure on the high-pressure side of the labyrinth seal.

[0051] Next, refer to Figure 13 and Figure 14 By adding the pressure balance adapter 190 as described above, the existing staged seal system 196 for reciprocating shaft compressors can be modified to provide the aforementioned pressure balance benefits. When assembled, the modified staged seal system ( Figure 14 A new pressure space 144a is defined between the pressure cut-off ring 138 and the seal 136a, and port 186 provides communication between this new pressure space 144a and the inlet of the associated compressor. The modified system is consistent with the above regarding... Figure 8 The described step-by-step sealing system works in a similar manner.

[0052] Specific embodiments of the subject matter have been described. Other embodiments, modifications, and substitutions of the described embodiments will be apparent to those skilled in the art and are within the scope of the following claims. Although operations are depicted in a particular order in the drawings or claims, this should not be construed as requiring such operations to be performed in the particular order shown or in sequential order, or requiring the performance of all illustrated operations (some operations may be considered optional) to achieve the desired result.

[0053] Therefore, the exemplary embodiments described above do not limit or restrict this disclosure. Other changes, substitutions, and modifications are possible without departing from the spirit and scope of this disclosure.

Claims

1. A gas processing system, the gas processing system comprising: The compressor cylinder (102) defines a cavity (106) for processing gas and includes a process gas inlet (108) for receiving process gas at an input pressure and a process gas outlet (110) for discharging process gas at an output pressure. A shaft (122) is connected to the compressor cylinder and configured to transfer mechanical energy to or from the gas in the compressor cylinder; as well as A step-by-step sealing system (114) defines an intermediate pressure space between the cavity and the atmosphere, located between adjacent seals (136) spaced apart along the axis. The intermediate pressure space (144a) located between the adjacent seals spaced along the axis is hydraulically connected to the process gas inlet of the compressor cylinder via a flow line (116) spaced apart from the axis. The gas handling system is configured such that, during operation, the maximum pressure in the intermediate pressure space is lower than the greater of the input pressure and the output pressure, but higher than atmospheric pressure.

2. The gas handling system according to claim 1, wherein, The output pressure is greater than the input pressure.

3. The gas processing system according to claim 1 or claim 2, wherein, The tiered sealing system defines a plurality of pressure spaces between adjacent seals (136) spaced apart along the axis, including an intermediate pressure space (144a) and a second pressure space, the second pressure space reaching a maximum pressure during operation that is lower than the maximum pressure in the intermediate pressure space (144a) but higher than atmospheric pressure.

4. The gas handling system according to claim 3, further comprising a purge gas source (128) hydraulically connected to the second pressure space (144c) and subject to sufficient pressure to allow purge gas to flow from the purge gas source away from the compressor cylinder along the axis into the staged sealing system.

5. The gas handling system according to claim 4, wherein, The plurality of pressure spaces include a venting pressure space (144e), which is hydraulically connected to a vent (132) for discharging at least some of the purge gases.

6. The gas handling system according to claim 3, wherein, The tiered sealing system includes a series of four seals (136) defining three pressure spaces (144).

7. The gas handling system according to claim 3, wherein, The plurality of pressure spaces include a pressure space (144c) that is hydraulically connected to a pressurized lubricating oil source (130).

8. The gas handling system according to claim 3, wherein, The intermediate pressure space is directly hydraulically connected to the process gas inlet (108).

9. The gas handling system according to claim 3, wherein the gas handling system is configured such that, during operation, the pressure in the intermediate pressure space (144a) is maintained within 30% of the input pressure.

10. The gas handling system according to claim 3, wherein, The streamline (116) is the only inlet or outlet for entering or leaving the intermediate pressure space (144a) during operation, except for the surface along the axis (122).

11. The gas handling system according to claim 3, wherein, The shaft reciprocates within the compressor cylinder and the staged sealing system.

12. The gas handling system according to claim 3, wherein, During the energy transfer between the shaft and the process gas within the compressor cylinder, the shaft rotates relative to the compressor cylinder, and the shaft rotates within the staged sealing system.

13. The gas handling system according to claim 12, wherein, The adjacent seals are adjacent portions of a continuous labyrinth seal, and the intermediate pressure space is the middle portion of the labyrinthine flow line passing through the seal.

14. The gas handling system according to claim 3, wherein, The streamline defines the throttling orifice (117).

15. The gas handling system according to claim 14, wherein, The throttling orifice is adjustable and / or controllable.

16. The gas handling system according to claim 3, wherein, The streamline defines a one-way valve (119) that restricts flow along the streamline toward the intermediate pressure space.

17. The gas handling system according to claim 3, wherein, Each of the seals is installed in a corresponding seal housing in a plurality of seal housings (140) connected together along the shaft (122).

18. The gas handling system according to claim 17, wherein, The streamline (116) is partially defined by aligned apertures (148) in the plurality of seal housings (140).

19. The gas handling system according to claim 3, wherein, The compressor cylinder, the shaft, and the staged sealing system are components of a first gas treatment stage. The gas treatment system also includes a second gas treatment stage having a second compressor cylinder, a second shaft, and a second staged sealing system. The first and second gas treatment stages are connected such that the output of the first gas treatment stage is connected to the input of the second gas treatment stage. The second staged sealing system defines a second intermediate pressure space, which is hydraulically connected to the process gas inlet of the compressor cylinder of the first gas treatment stage via a second flow line.

20. A method for modifying a step-by-step sealing system having a series of seals held in a stack of seal housings aligned to receive a shaft, the method comprising: A port housing is placed against the distal face of the stack of seal housings, the port housing defining a central bore sized to accommodate the shaft and housing a port in hydraulic communication with the central bore. The port housing accommodates an end seal configured to restrict flow along the shaft when the cascading sealing system is installed, wherein the end seal and the nearest seal in the series of seals define an intermediate pressure space in hydraulic communication with the port. During installation into the compressor cylinder of the gas handling system, the port is connected to the gas inlet of the compressor cylinder of the gas handling system.

21. The method according to claim 20, wherein, The port housing includes two separable housing portions, including a first portion defining the central aperture and a second portion containing the end seal.

22. The method according to claim 20 or claim 21, wherein, The end seal is a labyrinth seal.

23. The method according to claim 22, wherein, The modified step-by-step sealing system belongs to the gas handling system according to claim 1.

24. A method for sealing the shaft of a gas processing compressor cylinder, the gas processing compressor cylinder having a process gas outlet and a process gas inlet, wherein, The process gas outlet and the process gas inlet operate at different pressures, and the method includes: A plurality of seals are positioned along the axis, the seals defining at least one intermediate pressure space between adjacent seals; During operation of the gas processing compressor cylinder, the process gas leaking from the gas processing compressor cylinder into the intermediate pressure space is directly routed back to the process gas inlet of the gas processing compressor cylinder. The routed process gas flows due to the pressure difference between the intermediate pressure space and the process gas inlet of the gas processing compressor cylinder.

25. The method according to claim 24, wherein, The gas processing compressor cylinder belongs to the gas processing system according to any one of claims 1 to 19.

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