Gas processing system

Abstract

To provide a gas processing system that prevents increase in unnecessary emission of gas to the atmosphere.SOLUTION: A gas processing system includes a vessel defining a cavity for processing gas. The vessel includes a process gas inlet for accepting process gas at an input pressure, and a process gas outlet for discharging the process gas at an output pressure. The gas processing system further includes a shaft coupled to the vessel and a multistage sealing system comprising multiple seals spaced along the shaft. The shaft is configured to transfer mechanical energy to gas in the vessel or from gas in the vessel. Each adjacent pair of seals defines a corresponding pressure space therebetween. One of the pressure spaces is an equalizing pressure space in hydraulic communication with the process gas inlet via a flow pipe, such that in operation, a pressure in the equalizing pressure space is maintained at an equalized pressure with respect to a pressure in the process gas inlet.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a sealing shaft for high pressure gas processing equipment, such as a compressor, in particular having a progressive sealing system. [Background technology]

[0002] Progressive or multi-stage sealing systems are commonly utilized when high differential pressures must be maintained, such as between the atmosphere and a high-pressure cavity through which a moving shaft extends. Effective and reliable sealing often requires a sealing system that reduces pressure in stages along the shaft or along a labyrinth. The compression industry strives to increase maximum allowable operating pressures and system speeds in response to increasing customer specification demands. Summary of the Invention [Problem to be solved by the invention]

[0003] However, increased differential pressure typically makes it more difficult to contain the gas within the system and places more stress on the associated sealing elements, which can increase pressure pulsations within the system, lubricant consumption, and unwanted gas emissions to the atmosphere. [Means for solving the problem]

[0004] One aspect of the invention features a gas processing system having a vessel defining a cavity for processing 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 vessel and configured to transfer mechanical energy to or from the gas within the vessel. The system includes a progressive sealing system that defines an intermediate pressure space between adjacent seals spaced along the shaft between the cavity and the atmosphere. The maximum pressure in the intermediate pressure space is lower than the upper limit of the input and output pressures and greater than atmospheric pressure. "Progressive" means that the sealing system has multiple sealing members between high and low pressure points. Often, such systems provide a gradual reduction in pressure in stages between the high and low pressure points. Notably, the intermediate pressure space may be in hydraulic communication with the process gas inlet via a flow conduit spaced from the shaft. "Hydraulic" does not imply a liquid.

[0005] In some cases, such as in gas compressor systems, the output pressure is greater than the input pressure.

[0006] In some examples, the sealing system defines multiple pressure spaces between adjacent seals spaced along the shaft, the multiple pressure spaces including an intermediate pressure space and a second space that reaches a maximum pressure during operation that is lower than the maximum pressure in the intermediate pressure space and higher than atmospheric pressure.

[0007] Some embodiments also include a purge gas source in fluid communication with the second pressure space to flow purge gas under sufficient pressure from the purge gas source along the shaft and away from the vessel through the sealing system. The multiple pressure spaces can include, for example, a vent pressure space in fluid communication with a vent port that vents at least a portion of the purge gas.

[0008] In some examples, the sealing system has a series of four seals defining three pressure spaces. Some examples have a greater number of seals bordering individual pressure spaces. The multiple pressure spaces can include a pressure space in hydraulic communication with a pressurized source of lubricant.

[0009] In some embodiments, the intermediate pressure space is in direct hydraulic communication with the process gas inlet, where "directly" means that there are no system components between the flow path and the compressor inlet that actively work on the process gas by performing or removing work from the gas.

[0010] Preferably, for most applications, the pressure in the intermediate pressure space is maintained within 30 percent of the input pressure.

[0011] In many applications, the flow tube is the only inlet or outlet into or out of the intermediate pressure space during operation other than along the shaft surface.

[0012] In some embodiments, the vessel comprises a cylinder in which a shaft reciprocates, the shaft reciprocating within a sealing system. For example, the vessel may be a compressor cylinder.

[0013] In some other embodiments, the shaft rotates relative to the vessel during the transfer of energy between the shaft and the process gas within the vessel, and the shaft rotates within the sealing system. In some such embodiments, the adjacent seals are adjacent portions of a continuous labyrinth seal, and the intermediate pressure space is an intermediate portion of a labyrinth flow path through the seal.

[0014] In some examples, the flow path defines a restrictive orifice, which may be adjustable and / or controllable to affect flow along the flow path.

[0015] In some cases, the flow path includes a one-way valve that restricts flow along the flow path toward the intermediate pressure space, for example, inhibiting the flow of process gas entering the sealing system through the inlet.

[0016] In some embodiments, each of the seals is assembled within a respective one of a plurality of seal housings coupled together along the shaft. The flow tube may be defined in part by aligned openings in the plurality of seal housings.

[0017] In some embodiments, the vessel, shaft, and sealing system are components of a first gas processing stage, and the gas processing system further includes a second gas processing stage having a second vessel, a second shaft, and a second multi-stage sealing system. The first gas processing stage and the second gas processing stage are connected such that an output of the first gas processing stage is connected to an input of the second gas processing stage. The second multi-stage sealing system defines a second intermediate pressure space in hydraulic communication with a process gas inlet of the vessel of the first gas processing stage via a second flow conduit.

[0018] Another aspect of the invention features a method of modifying a progressive sealing system having a series of seals held within a seal housing laminate, the seal housing laminate being aligned to receive a shaft therethrough. The method includes placing a port housing against a distal face of the seal housing laminate, a port defining a central opening sized to accommodate the shaft, the port being in hydraulic communication with the central opening. The port housing also houses end seals configured to restrict flow along the shaft with an installed sealing system, the end seal and the nearest seal in the series defining an intermediate pressure space therebetween in hydraulic communication with the port. During installation in a gas processing system vessel, the port is connected to an inlet of the gas processing system by a flow tube.

[0019] In some embodiments, the port housing comprises two separable housing portions, including a first portion defining a central opening and a second portion accommodating an end seal.

[0020] In some cases, the end seals are labyrinth seals.

[0021] Another aspect of the invention features a method for sealing a shaft of a gas processing vessel having an outlet and an inlet operating at different pressures. The method includes disposing a plurality of seals along the shaft, the seals defining at least one intermediate pressure space between adjacent seals, and routing process gas leaking from the vessel during operation of the gas processing vessel to the intermediate pressure space and directly back to the inlet of the gas processing vessel, the routed process gas flowing due to a pressure differential between the intermediate pressure space and the vessel inlet.

[0022] The present invention has particular utility in the context of gas processing systems having high-pressure vessels, such as compressors, with shafts and multi-stage shaft sealing systems. In many instances, the invention features recirculating process gas that leaks past at least a portion of a seal back to the vessel's process gas inlet. This internal recirculation of leaked process gas can effectively reduce pressure between and pressure differentials across the various seals. The reduced pressure differential can reduce seal contact pressure and heat generation, while gas expansion can provide a cooling effect along the sealing system. The improvements disclosed herein can also extend seal life and reduce pressure pulsations and process gas losses, as well as lubricant consumption.

[0023] The details of one or more embodiments of the presently disclosed subject matter 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. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram of a single-stage gas processing system having a multi-stage sealing system. [Figure 2] FIG. 1 is a perspective view of a portion of a reciprocating shaft compressor. [Figure 3] FIG. 3 is an end view of the compressor portion of FIG. 2. [Figure 4] 4 is a cross-sectional view taken along line 4 / 5-4 / 5 of FIG. 3, showing the shaft at each end of its travel. [Figure 5]4 is a cross-sectional view taken along line 4 / 5-4 / 5 of FIG. 3, showing the shaft at each end of its travel. [Figure 6] FIG. 6 is a partial cross-sectional view taken along line 6-6 of FIG. 3. [Figure 7] FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 3. [Figure 8] FIG. 8 is an enlarged cross-sectional view of the multi-stage sealing system taken along line 8-8 of FIG. 3. [Figure 9] FIG. 3 is an exploded view of the compressor portion of FIG. 2. [Figure 10] 1 is a schematic diagram of a multi-stage gas processing system having two compressors, each compressor having a multi-stage sealing system. [Figure 11] FIG. 1 is a cross-sectional view of a rotating multi-stage sealing system with integrated pressure equalization. [Figure 12] FIG. 1 is a cross-sectional view of a rotating multi-stage sealing system adapted for adding pressure equalization. [Figure 13] FIG. 1 is a cross-sectional view of a standard multi-stage sealing system for a reciprocating shaft and an adapter that adds pressure equalization. [Figure 14] FIG. 14 is a diagram of the sealing system and adapter of FIG. 13 joined together to form a sealing system with pressure equalization. DETAILED DESCRIPTION OF THE INVENTION

[0025] Like reference numbers in the various drawings indicate like elements.

[0026] 1 , a gas processing system 100 includes a compressor 102 having a vessel 104 defining a cavity 106 having a process gas inlet 108 and a process gas outlet 110. The compressor 102 may be, for example, a positive displacement compressor (e.g., a rotary compressor such as a lobe compressor, screw compressor, scroll compressor, or vane compressor, or a reciprocating compressor such as a double-acting compressor) or a dynamic compressor (e.g., a centrifugal compressor or an axial compressor). The vessel 104, configured to contain the process gas, is operably coupled to a shaft extending within the compressor. A multi-stage sealing system 114, here represented by a series of boxes along the shaft, inhibits leakage of the process gas along the shaft. The shaft transfers mechanical energy to the process gas within the vessel 104 (e.g., by rotating about its longitudinal axis or translating along its longitudinal axis) and extends through a multi-stage sealing system 114 into the cavity 106. In one example, the shaft drives a compressor wheel inside the vessel 104 to substantially increase the pressure at the outlet 110 relative to the pressure at the inlet 108. For example, the process gas may enter the process gas inlet 108 at a pressure of approximately 800 psig and exit through the process gas outlet 110 at a pressure of approximately 1500 psig. Preferably, the compressor has a compression ratio of at least 1.5:1. As shown, a flow path 116 directs process gas that leaks between two seals of the multi-stage sealing system 114 toward the gas flow entering the inlet 108. As shown, the flow path 116 connects directly to the compressor inlet. In this context, direct means that there are no system components between the flow path and the compressor inlet that actively work on the process gas by performing work on the gas or removing work from the gas. The flow path 116 may include a restrictor orifice 117 that may be adjustable or actively controllably fixed to optimize flow along the flow path 116 for particular operating conditions. For some applications, a one-way check valve 119 may be provided along the flow path to prevent flow from the inlet 108 to the sealing system.

[0027] 2, the cylinder of the compressor 102 has a housing 118 and end plates 120 that are bolted to the housing, through which a shaft 122 extends. The compressor cylinder 102 is a linear reciprocating compressor and has two inlets 108 and two outlets 110. A conduit 124 forms part of a flow path (116 in FIG. 1) that feeds leaked process gas back to one of the two inlets.

[0028] 3, this particular end plate 120 has four ports that communicate with the compressor's multi-stage sealing system. These ports include a pressure equalization port 126, a purge gas port 128, a lubricant port 130, and a vent port 132. In some instances, there may be fewer or more ports.

[0029] 4 and 5, the multi-stage sealing system 114 is disposed around the shaft 122 and includes, in this example, five seals 136 spaced along the shaft and a pressure interrupter rod ring 138. Each seal may include multiple sealing elements, or rod rings, stacked closely together on the shaft to form a tight series of sealing interfaces with the shaft. The rod ring 138 is a single-element seal that forms the first seal of the multi-stage sealing system, controlling leakage and regulating backflow into the cylinder during the intake stroke, avoiding ring damage and separation of the ring from the rod. The pressure interrupter also reduces gas flow exiting the cylinder during the exhaust stroke. The rod ring 138 may be modified to provide an optimal, effective orifice for the expected flow back to the inlet from behind the rod ring, as described below. The term "seal" does not imply zero clearance at the shaft face or absence of leakage across the seal. As will be appreciated by those skilled in the art of high pressure gas machinery, some leakage past the high pressure differential seal is to be expected and may even be necessary to avoid high friction and premature seal failure. The expansion of gas between the seal and shaft face can provide beneficial cooling to the shaft and less wear on the seal.

[0030] The compressor cylinder inlet 108 and outlet 110 each feature a one-way valve that allows flow into (inlet) or out of (outlet) the compressor cylinder while preventing flow in the opposite direction. Each valve may have multiple flow openings simultaneously. The inlets and outlets operate in pairs, with each pair operating in a different direction along the shaft. For example, during a piston stroke from right to left, the right inlet 108 and left outlet 110 open at different points during the stroke. Similarly, during a return stroke from left to right, the left inlet 108 and right outlet 110 open at different points during the stroke, while the right inlet and left outlet remain closed. During this return stroke from left to right, the sealed end of the cylinder experiences a pressure buildup to at least the compressor outlet pressure. This high pressure gradually decreases along the shaft through various stages, beginning with the pressure interrupter rod ring 138. During the right-to-left stroke, the instantaneous pressure at the pressure interrupter rod ring can sometimes fall below the compressor inlet or suction pressure, causing flow in conduit 124 to reverse toward the sealing system. Therefore, the sealing system not only needs to withstand high pressures, but also accommodate extreme pressure waves or cycles that can fluctuate quite rapidly.

[0031] As shown in these cross-sectional views, the multi-stage sealing system includes multiple seal housings 140 stacked along the shaft and disposed within the bore of housing 118. The innermost seal housing is sealed against the face of the cylinder housing by a nose gasket 141. In some cases, housing 118 is two-piece, with a cast iron component forming the main cylinder and a steel bulkhead bolted to the end of the cylinder to house the sealing system. Each seal housing 140 houses a respective seal 136, with the outermost seal (double-acting ring) housed within end plate 120. As understood in the art, each seal 136 may be a stack of multiple elements, such as a seal ring sandwiched between two other rings that support the sealing function. All seal housings are axially connected to end plate 120 by tie rods 142 that thread into the distal seal housing, which houses the pressure interrupter rod ring, to hold the seal housing stack together for shipping and assembly. The tie rod 142 may also provide an alignment function. The seal housings have aligned passages, connecting the ports in the end plates with specific spaces between the seals. For example, these cross sections show that the lubrication port 130 communicates with the space between the second and third seals along the shaft, allowing lubrication introduced through the port 130 to reach the shaft face between these two seals and lubricate at least a portion of the sealing interface of the sealing system. Note that the third seal housing from the left has a blind passage that does not communicate with the lubrication port. This seal housing serves no purpose but is a result of using the same seal housing design for multiple seal housings in the assembly. As shown in Figure 6, the vent port 132 communicates with the space between the two outermost seals and serves to collect any residual process gas that leaks past the first four seals, allowing it to be safely collected or destroyed without reaching the atmosphere.

[0032] 7 and 8, the multi-stage sealing system defines pressure spaces along the shaft surface where the various seals meet. Moving from the high-pressure end to the atmospheric end of the sealing system, high-pressure process gas leaking past the pressure-break rod ring 138 first reaches an intermediate pressure space 144a between the pressure-break rod ring 138 and the first seal 136a, which is comprised of three stacked sealing elements or rod rings 146. It is this pressure space 144a that communicates with the pressure equalization port 126, which returns a portion of the leaking process gas that enters this first space to the low-pressure inlet of the compressor. Returning gas from the 800 psig pressure space 144a to the compressor inlet, for example, can result in an operating pressure of only 800 psig within the space 144a. In other words, there can be a pressure differential of approximately 700 psig across the first seal (pressure-break rod ring 138), or an overall pressure differential of between 40 and 60 percent across the multi-stage sealing system. Process gas leaking from intermediate pressure space 144a past seal 136a enters pressure space 144b at a pressure of, for example, about 600 psig. Further leakage past seal 136b reaches pressure space 144c, which may be, for example, about 500 psig. As shown in these cross sections, purge gas port 128 communicates with pressure space 144c, which is the same space that the lubrication port communicates with. Thus, during operation, the multi-stage sealing system defines a series of pressure spaces with decreasing pressure along the shaft, with each seal generating a pressure differential between two pressure spaces. The amount of leakage flowing past the seal and the pressure differential across the seal are interrelated. Generally, the higher the pressure differential across the seal, the higher the flow friction against the seal and the higher the heat generation at the seal. As noted above, pressure equalization in pressure space 144a via pressure equalization port 126 results in a pressure profile of 1500-800-600-500-200-50-0 psig along the multi-stage sealing system. Without such pressure equalization, the pressure profile under similar operating conditions might be 1500-1200-1000-600-250-50-0 psig. The pressure equalization provided via pressure equalization port 126 also reduces pressure pulsations within the sealing system.

[0033] In some cases, a 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 to displace any leaks in seal 136b toward the compressor. In such cases, the pressure profile is 1500-800-600-620-400-200-0 psig, and the gas sent back to the compressor inlet can 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.

[0034] As best seen in FIG. 8, hydraulic communication between the pressure equalization port 126 and the space 144a (exposed to the shaft face) is via an aligned passage 148 in the laminated seal housing 140 to a recess 150 behind the seal 136a. This recess opens into the pressure space 136a at the leading edge of the seal. The recess and the aligned passage 148 form a portion of the flow path (116 in FIG. 1) returning to the compressor inlet. Flow from the pressure space 144a back to the compressor inlet can be controlled either passively by an orifice along the flow path or actively by a valve controlled in response to a pressure signal to maintain a desired flow pressure in the pressure space 144a. In such a case, the pressure space 144a is at a somewhat higher pressure than the compressor inlet, but still at a lower pressure than would be the case without pressure equalization. It should be noted that while pressure equalization port 126 is shown communicating with pressure space 144a between pressure isolation rod ring 138 and seal 136a, it could alternatively communicate with pressure space 144b between seals 136a and 136b, in which case the pressure profile could be 1500-1200-800-600-400-200-0 psig.

[0035] Referring now to FIG. 9, the connected stack of end plate 120 and its seal housing 140, aligned and held together by tie rods 142, is inserted into holes in compressor housing 118 and held in place by housing bolts 152.

[0036] Referring to FIG. 10 , for some applications, compressors 102 may be coupled in series to generate higher operating pressures. In this example, a multi-stage compression system 154 is comprised of two compressors 102 coupled in series, with the output 110a of the first compression stage feeding the input 108b of the second stage. The first compression stage, as described above, includes a flow path 116a that returns gas to the compressor inlet 108a from a designated space between the seals in the first multi-stage sealing system. In system 154, flow path 116b similarly feeds gas to the first stage compressor inlet 108a from a designated space between the seals in the second multi-stage sealing system. Flow path 116b can be throttled as needed to create a desired pressure profile for the second compression stage, assuming the pressure of output 110b is significantly higher than the pressure of output 110a.

[0037] The above system has been described for a reciprocating compressor, where shaft force acts on the process gas to create a high pressure gas flow that can be used to do work elsewhere in the system. The same sealing principles can be applied to a linear reciprocating gas engine, where the high pressure gas flow is used to drive a shaft back and forth.

[0038] The same pressure equalization principles can also be utilized within rotary shaft sealing systems. Referring to FIG. 11 , a rotary multi-stage shaft sealing system 160 is utilized to seal a rotary shaft 162 extending from a high-pressure vessel (not shown), with the left end of the sealing system exposed to high vessel pressure 164. At the high-pressure end of the sealing system, a labyrinth seal 166 engages the seal at multiple points along its length, effectively tapering the pressure along the width of the labyrinth between the high vessel pressure and a first pressure space 168. A first-stage sliding seal interface 170 separates pressure space 168 from a second pressure space 172. A second-stage sliding seal interface 174 separates pressure space 172 from a third pressure space 176, which is exposed to a shaft seal 178 at the low-pressure end of the sealing system. Purge gas port 180 allows pressurized purge gas, such as nitrogen, to be delivered to first pressure space 168, and vent port 182 allows the mixture of leaking treatment gas and purge gas to be removed from the system and recovered / discarded / destroyed. An optional second vent port 184 allows residual gas to be vented from pressure space 176. Pressure equalization is achieved by connecting equalization pressure port 186 to the low-pressure (input) side of the compressor, as described above. Such a connection effectively enhances the pressure drop along the labyrinth seal, lowering the pressure in pressure space 168 and thereby reducing the pressure differential that sliding seal interfaces 170 and 174 must maintain.

[0039] In the above example, the pressure equalization port and associated passages are integrated into the sealing system. However, the principles described above can be applied to existing multi-stage sealing systems by providing appropriate retrofit hardware. For example, the system shown in FIG. 12 includes a typical rotating shaft multi-stage sealing system 188 and a pressure equalization adapter 190 that are bolted or otherwise secured around the shaft 162 at the high-pressure end of the sealing system. The adapter 190 includes an adapter housing 192 that is configured to be mechanically secured to the existing sealing system housing, contains the pressure isolation rod ring 138, and defines the pressure equalization port. In the illustrated example, the adapter housing is a stack of two plates, one defining the pressure equalization port and the other housing the rod ring. When the adapter is installed in an existing sealing system, a new pressure space 194 is defined between the pressure isolation rod ring 138 and the labyrinth seal 166. Thus, the pressure in pressure space 194 is relieved by the pressure equalization system, reducing the pressure on the high pressure side of the labyrinth seal.

[0040] 13 and 14, an existing multi-stage sealing system 196 for a reciprocating shaft compressor may be modified to provide the pressure equalization benefits described above by adding a bolted adapter 190 as described above. Upon assembly, the modified multi-stage sealing system (FIG. 14) defines a new pressure space 144a between pressure isolation rod seal 138 and seal 136a, with port 186 providing communication between this new pressure space 144a and the associated compressor inlet. This modified system functions similarly to the system described above with respect to FIG. 8.

[0041] Specific embodiments of the subject matter have been described. Other embodiments, modifications, and permutations to the described embodiments, as will be apparent to those skilled in the art, are within the scope of the following claims. Although operations are shown in the figures or in the claims in a particular order, this order should not be understood as requiring such operations to be performed in the particular order shown, or in sequential order, or that all of the illustrated operations be performed (some operations may be considered optional) to achieve desired results.

[0042] Therefore, the exemplary embodiments set forth above do not define or constrain this disclosure, and other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.

Claims

1. 1. A gas processing system, comprising: a vessel defining a cavity for processing gas, the vessel including a process gas inlet for receiving process gas into the cavity at an input pressure, and a process gas outlet for discharging process gas from the cavity at an output pressure; a shaft coupled to the vessel and configured to transfer mechanical energy to or from gas within the vessel; a progressive sealing system comprising a series of adjacent seals spaced along the shaft between the cavity and atmosphere and configured to provide a stepwise reduction in pressure, two of the adjacent seals defining an intermediate pressure space therebetween, the intermediate pressure space being in fluid communication with the process gas inlet via a flow conduit spaced from the shaft; The intermediate pressure space is at a pressure lower than a first adjacent space on the opposite side of one of the two adjacent seals and greater than a second adjacent space on the opposite side of the other of the two adjacent seals. A gas processing system comprising:

2. A portion of the process gas flows through the first adjacent space to the intermediate pressure space. The gas processing system of claim 1 .

3. At least a subset of the portion of the process gas flows through the intermediate pressure space to the second adjacent space. The gas processing system of claim 2 .

4. The progressive sealing system comprises: a high pressure end adjacent the cavity; an atmospheric pressure end distal to the cavity and opposite the high pressure end with respect to the series of adjacent seals; The progressive sealing system comprises a plurality of pressure spaces, each pressure space being defined by a respective pair of adjacent seals in the series of adjacent seals, the plurality of pressure spaces comprising: a first pressure space among the plurality of pressure spaces that is closest to the high pressure end; a final pressure space among the plurality of pressure spaces that is closest to the atmospheric pressure end, Each pressure space downstream of the first pressure space has a lower pressure than the upstream pressure space adjacent to each pressure space. The gas processing system of claim 1 .

5. The vessel is a gas compressor vessel. The gas processing system of claim 1 .

6. The gas compressor vessel is a cylinder of a gas compressor. The gas processing system of claim 5 .

7. The shaft is a reciprocating shaft. The gas processing system of claim 1 .

8. The shaft rotates relative to the vessel during energy transfer between the shaft and the process gas in the vessel, and the shaft rotates within the progressive sealing system. The gas processing system of claim 1 .

9. The intermediate pressure space is in direct hydraulic communication with the process gas inlet such that gas flows from the intermediate pressure space to the process gas inlet without flowing through any system component that actively performs work on or removes work from the gas. The gas processing system of claim 1 .

10. The progressive sealing system further comprising a series of laminated seal housings; The flow path between the intermediate pressure space and the processing gas inlet includes: the flow tube; an internal cavity defined by the series of stacked housings, the internal cavity comprising: a recess adjacent to the intermediate pressure space; and a series of aligned passages, said series of aligned passages comprising: a first passageway adjacent to and in fluid communication with the recess, the first passageway being defined by one seal housing of the series of laminated seal housings; a second passageway adjacent to and in fluid communication with the first passageway, the second passageway being defined by an adjacent seal housing of the series of laminated seal housings; The first passageway and the second passageway have a common central axis that is parallel to the longitudinal axis of the shaft. The gas processing system of claim 1 .

11. A gas processing system, comprising: a vessel defining a cavity for processing gas, the vessel including a process gas inlet for receiving process gas into the cavity at an input pressure, and a process gas outlet for discharging process gas from the cavity at an output pressure; a shaft coupled to the vessel and configured to transfer mechanical energy to or from gas within the vessel; a progressive sealing system comprising a series of adjacent seals spaced along the shaft and configured to provide a stepwise reduction in pressure between the cavity and atmosphere, two of the adjacent seals defining an intermediate pressure space therebetween; The intermediate pressure space is in fluid communication with the process gas inlet through a flow tube spaced from the shaft, the flow tube including a controllable orifice between the intermediate pressure space and the process gas inlet that controls flow along the flow tube. A gas processing system comprising:

12. The progressive sealing system further comprises a series of laminated seal housings; The flow path between the intermediate pressure space and the processing gas inlet includes: the flow tube; an internal cavity defined by the series of stacked housings, the internal cavity comprising: a recess adjacent to the intermediate pressure space; a series of aligned passages; The gas processing system of claim 11.

13. The recess is in fluid communication with the intermediate pressure space, and the series of aligned passages are: a first passageway adjacent to and in fluid communication with the recess, the first passageway being defined by one seal housing of the series of laminated seal housings; a second passageway adjacent to and in fluid communication with the first passageway, the second passageway being defined by an adjacent seal housing of the series of laminated seal housings; The first passageway and the second passageway have a common central axis that is parallel to the longitudinal axis of the shaft. The gas processing system of claim 12.

14. The method of claim 1, further comprising an end plate having a pressure equalization port; A portion of the process gas flows along the flow path between the intermediate pressure space and the pressure equalization port through the internal cavity defined by the series of stacked housings. The gas processing system of claim 12.

15. The end plate accommodates an outermost seal that is distal to the container relative to other seals in the series of adjacent seals; the end plate defines a passageway in fluid communication with the series of aligned passageways; The flow tube is coupled to the passage defined by the end plate through the pressure equalization port.

15. The gas processing system of claim 14.

16. The passages defined by the end plates have central axes that are at a non-zero angle with respect to a common central axis of the series of aligned passages, the common central axis being parallel to the longitudinal axis of the shaft.

16. The gas processing system of claim 15.

17. The container is a cylinder of a gas compressor. The gas processing system of claim 11.

18. The shaft is a reciprocating shaft. The gas processing system of claim 11.

19. The intermediate pressure space is in direct hydraulic communication with the process gas inlet such that gas flows from the intermediate pressure space to the process gas inlet without flowing through any system component that actively performs work on or removes work from the gas. The gas processing system of claim 11.

20. The progressive sealing system comprises a plurality of pressure spaces, each pressure space being defined by a respective pair of adjacent seals in the series of adjacent seals, and the plurality of pressure spaces being: the intermediate pressure space; a first adjacent space on an opposite side of one of the two adjacent seals; a second adjacent space on the other side of the two adjacent seals; a portion of the process gas flows through the first adjacent space to the intermediate pressure space; At least a subset of the portion of the process gas flows through the intermediate pressure space to the second adjacent space. The gas processing system of claim 11.

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