Filling system of valve assembly

Abstract

The invention relates to a valve assembly packing system. A packing system for use with a valve having a valve body defining a flow passage therethrough is disclosed. The packing system includes: a valve cover configured for connection to a valve body; a stem bore extending through the bonnet to receive a stem of the valve, the stem being movable within the stem bore to control flow through the flow passage; the first packing group is arranged in the valve rod hole and surrounds the first part of the valve rod; the second packing group is arranged in the valve rod hole and surrounds a second part of the valve rod, and the second packing group is separated from the first packing group through a supporting ring so as to limit a packing space volume in the valve rod hole; and a pressurized barrier lubricant reservoir in fluid communication with the packed room volume via a bonnet port in the bonnet to pressurize the barrier lubricant within the packed room volume at or above the process pressure.

Description

Technical Field

[0001] The present application relates to a packing system for a valve assembly. Background Art

[0002] Valve assemblies, including control valves, can be used in a wide range of applications, including process plants such as refineries, chemical plants, and paper mills, as well as other applications. In some applications, the packing system of a control valve can help limit fugitive emissions from the packing system. For example, an arrangement of packing material can surround the stem of a control valve to help prevent process fluid from leaking through the stem to the surrounding environment. Summary of the invention

[0003] In general, some examples disclosed herein may provide a packing system for use with a valve, the valve comprising a valve body having an inlet, an outlet, and a flow passage extending between the inlet and the outlet. The packing system may include: a valve cover configured to be connected to the valve body; a valve stem hole extending through the valve cover to open into the valve body to receive a valve stem of the valve so that the valve stem can move within the valve stem hole to control flow through the flow passage; a first packing group disposed in the valve stem hole to surround a first portion of the valve stem; a second packing group disposed in the valve stem hole to surround a second portion of the valve stem; and a pressurized barrier lubricant reservoir. The first packing group may be disposed between the second packing group and the valve body, and wherein the second packing group is spaced apart from the first packing group by a support ring to define an inter-packing volume within the valve stem hole. The pressurized barrier lubricant reservoir may be in fluid communication with the inter-packing volume via a bonnet port in the bonnet to pressurize the barrier lubricant within the inter-packing volume to be at or above a first pressure.

[0004] In some examples, the pressurized barrier lubricant reservoir may be secured to the valve cover at the valve cover port.

[0005] In some examples, the pressurized barrier lubricant reservoir can be arranged to sense a process pressure at a location upstream of the first packing set relative to a leakage flow path from the flow passage through the valve stem bore to pressurize the barrier lubricant above the process pressure. In some such examples, the pressurized barrier lubricant reservoir can include: a spring-biased piston arranged to compress a barrier lubricant chamber; an outlet port arranged to connect the barrier lubricant chamber to the valve cover port; and a process port piped to the process pressure to assist the spring-biased piston, wherein the process port is fluidly isolated from the barrier lubricant chamber.

[0006] In some examples, the bonnet port can be a first bonnet port, the pressurized barrier lubricant reservoir can be a first pressurized barrier lubricant reservoir, the support ring can be a first support ring, the packing volume can be a first packing volume, and the packing system can also include a third packing group and a second pressurized barrier lubricant reservoir. The third packing group can be arranged in the valve stem bore to surround a third portion of the valve stem and be spaced apart from the second packing group by a second support ring to define a second packing volume within the valve stem bore, wherein the third packing group is between the first packing group and the second packing group. The second pressurized barrier lubricant reservoir can be in fluid communication with the second packing volume via a second bonnet port in the bonnet to pressurize the barrier lubricant in the second packing volume to be at or above a second pressure, the second pressure being higher than the first pressure. In some such examples, the second pressurized barrier lubricant reservoir can be arranged to sense a process pressure upstream of the first packing group relative to a leakage flow path from the flow channel through the valve stem hole to pressurize the barrier lubricant in the second pressurized barrier lubricant reservoir to above the process pressure. In other such examples, the packing system may also include a fourth packing group and a booster system. The fourth packing group may be arranged in the valve stem hole to surround a fourth portion of the valve stem and be spaced apart from the first packing group by a third support ring to define a third packing volume within the valve stem hole, wherein the fourth packing group is between the first packing group and the valve body. The booster system may be arranged to pressurize a process fluid upstream of the fourth packing group relative to a leakage flow path from the flow channel through the valve stem hole, and provide the pressurized process fluid to the third packing volume via a third valve cover port in the valve cover.

[0007] In some examples, the packing system may also include a sensor arrangement that may be configured to sense flow of barrier lubricant to the bonnet port and a control system that may be configured to determine leakage of barrier lubricant from the inter-packing volume.

[0008] Some examples of the present disclosure provide a valve assembly for a process flow at a process pressure. The valve assembly may include a valve body, a valve cover, a valve stem, a first packing group, a second packing group, and a valve cover port. The valve body may include an inlet, an outlet, and a flow channel extending between the inlet and the outlet to guide the process flow. The valve cover may be mounted to the valve body and may have a valve stem hole leading to the valve body. The valve stem may extend through the valve stem hole and may be operably connected to a control member arranged in the flow channel. The valve stem may be configured to move the control member between a closed position and an open position to control flow through the flow channel. The first packing group may be arranged around a first portion of the valve stem in the valve stem hole. The second packing group may be arranged around a second portion of the valve stem in the valve stem hole, downstream of the first packing group relative to a leakage flow path from the flow channel through the valve stem hole, to provide a packing inter-group volume between the first packing group and the second packing group within the valve stem hole. The bonnet port may extend through the bonnet to provide fluid communication between the packing volume and a source of pressurized fluid at a first pressure that is higher than the process pressure.

[0009] In some examples, the pressurized fluid source can be a pressurized barrier lubricant reservoir. In some such examples, the pressurized barrier lubricant reservoir can be connected to the valve stem bore in an upstream line of the first packing set relative to the leakage flow path to pressurize the barrier lubricant in the pressurized barrier lubricant reservoir to above the process pressure.

[0010] In some examples, the bonnet port may be a first bonnet port, the pressurized fluid source may be a first pressurized fluid source, the packing volume may be a first packing volume, and the valve assembly may further include a third packing group and a second bonnet port. The third packing group may be arranged around a third portion of the valve stem in the valve stem bore, and the third packing group may be downstream of the second packing group along the leakage flow path to define a second packing volume between the second packing group and the third packing group within the valve stem bore. The second bonnet port may extend through the bonnet to provide fluid communication between the second packing volume and a second pressurized fluid source at a second pressure, the second pressure being higher than the first pressure. In some such examples, the second pressurized fluid source may be a pressurized barrier lubricant reservoir. In some such examples, the pressurized barrier lubricant reservoir may be connected to the valve stem bore in a line upstream of the first packing group relative to the leakage flow path to pressurize the barrier lubricant within the pressurized barrier lubricant reservoir to a pressure higher than the process pressure. In other such examples, the valve assembly may further include a fourth packing group and a booster system. The fourth packing group may be arranged in the valve stem bore around a fourth portion of the valve stem, the fourth packing group may be upstream of the first packing group along the leakage flow path to define a third packing volume within the valve stem bore, wherein the fourth packing group is between the first packing group and the valve body. The booster system may be arranged to pressurize a process fluid from upstream of the fourth packing group relative to the leakage flow path, and provide the pressurized process fluid to the third packing volume via a third valve cover port in the valve cover. In some such examples, the booster system may include a pneumatic pump, which may be arranged to pressurize the process fluid.

[0011] In some examples, the valve assembly may further include a sensor arrangement that may be configured to sense the flow of fluid through the bonnet port.

[0012] Some examples of the present disclosure provide a packing system for use with a valve assembly, the valve assembly comprising: a valve body having an inlet, an outlet, and a flow channel extending between the inlet and the outlet; and a valve cover having a valve stem hole, the valve stem hole receiving a valve stem to control flow through the flow channel. The packing system may include a first packing group, a second packing group, and a barrier lubricant. The first packing group may surround a first portion of the valve stem in the valve stem hole and may be compressed to provide a first pressure drop along a leakage flow path from the flow channel through the valve stem hole. The second packing group may surround a second portion of the valve stem in the valve stem hole, the second packing group may be downstream of the first packing group relative to the leakage flow path to provide a first packing volume between the first packing group and the second packing group within the valve stem hole. The second packing group may be compressed to provide a second pressure drop along the leakage flow path, the second pressure drop being greater than the first pressure drop. The barrier lubricant may be pressurized to a first pressure within the first packing volume.

[0013] In some examples, the packing system may further include a third packing group surrounding a third portion of the valve stem in the valve stem bore, the third packing group being downstream of the second packing group relative to the leakage flow path to provide a second packing volume between the second packing group and the third packing group within the valve stem bore, and being compressed to provide a third pressure drop along the leakage flow path, the third pressure drop being greater than the second pressure drop. In some such examples, the packing system may further include a barrier lubricant pressurized to a second pressure within the second packing volume, the second pressure being higher than the first pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate examples of the disclosed technology and, together with the description, serve to explain the principles of the disclosed technology:

[0015] Figure 1 is a cross-sectional partial schematic diagram of an example valve assembly with a packing system according to the principles of the present disclosure;

[0016] Figure 2 yes Figure 1 A partial schematic enlarged view of a packing system of a valve assembly, wherein the valve body is not shown;

[0017] Figure 3 is a graph showing the process pressure and Figure 1 A diagram showing a relationship between a first packing pressure differential and a second packing pressure differential of a packing system of a valve assembly;

[0018] Figure 4 According to the principles of the present disclosure Figure 1 A cross-sectional view of another example configuration of a packing system of a valve assembly;

[0019] Figure 5 is a graph showing the process pressure and Figure 4 A diagram of the relationship between a first packing pressure differential and a second packing pressure differential for a valve assembly configuration;

[0020] Figure 6 According to the principles of the present disclosure Figure 1 A cross-sectional view of yet another example configuration of a packing system of a valve assembly;

[0021] Figure 7 is a graph showing the process pressure and Figure 6 a diagram showing the relationship between a first packing pressure differential, a second packing pressure differential, and a third packing pressure differential for a valve assembly configuration;

[0022] Figure 8 According to the principles of the present disclosure Figure 1 A cross-sectional view of yet another exemplary configuration of a packing system of a valve assembly;

[0023] Fig. 9 is a graph showing the process pressure and Figure 8 A diagram showing the relationship between a first packing pressure differential, a second packing pressure differential, a third packing pressure differential and a fourth packing pressure differential for a valve assembly configuration. DETAILED DESCRIPTION

[0024] The following discussion is proposed to enable those skilled in the art to make and use examples of the disclosed technology. Without departing from the disclosed technical principles, it will be easy for those skilled in the art to understand various modifications of the illustrated examples, and the general principles of this article can be applied to other examples and applications. Therefore, the disclosed technology is not intended to be limited to the examples shown, but is given the widest scope consistent with the principles and features disclosed herein. The following detailed description will be read with reference to the accompanying drawings, in which the same elements in different drawings have the same reference numerals. The drawings, which are not necessarily drawn to scale, depict selected examples and are not intended to limit the scope of the disclosed technology. The technician will recognize that the examples provided herein have many useful alternatives and fall within the scope of the present disclosure as a whole.

[0025] Before explaining any example in detail, it should be understood that the present disclosure is not limited to the construction details and component arrangements set forth in the following description or shown in the accompanying drawings. The disclosed technology can have other configurations and can be practiced or executed in various ways. In addition, it should be understood that the words and terms used herein are for descriptive purposes and should not be considered restrictive. For example, the use of "including", "comprising" or "having" and its variants herein is intended to cover the items listed thereafter and their equivalents and additional items. The use of "about" or "approximately" and its variants herein is intended to refer to changes in numerical quantities, which may occur, for example, because of measuring pressures or temperatures in various parts of the valve assembly that may include examples disclosed herein; because of unintentional errors in these procedures; because of differences in the accuracy or precision of various components used to perform the method, etc. Throughout this disclosure, the terms "about" and "approximately" are intended to refer to a ±5% value range (including the end value) of the numerical value following the term.

[0026] As briefly discussed above, a valve assembly can be used to control the flow of a process fluid from a fluid source toward a downstream application. The valve assembly can, for example, have a main valve inlet and a main valve outlet. A main flow channel can extend between the main valve inlet and the main valve outlet and through a main valve body. The main valve body can include a control member (such as a valve plug or a valve disc), for example to manipulate a process fluid such as steam, water, natural gas, oil or other chemical compounds flowing through a pipeline. The control member is typically moved by an operating member (such as a sliding valve stem or a rotating shaft) extending through a hole in the valve body. In order to prevent leakage or fugitive discharge of the process fluid around the operating member, a packing arrangement is typically provided around the operating member in the hole of the valve body.

[0027] Control valves used in many process applications (including those involving aromatic or chlorinated hydrocarbons) tend to leak small amounts of process fluid into the surrounding environment (i.e., produce fugitive emissions). Conventional solutions for reducing fugitive emissions involve placing metal bellows seals around operating members to capture process leaks, or applying compressive stresses on packing materials to form a tight seal between the operating member and the valve body bore. However, these solutions may have undesirable effects on the operation and performance of the control valve. For example, increasing packing stress tends to increase the friction experienced by the operating member (e.g., a sliding valve stem). The increased friction may hinder the movement of the operating member, which in turn may make it difficult to monitor and control the position of the operating member. Higher friction levels may also require larger actuators, which may increase the operating and manufacturing costs associated with the control valve. In addition, the increased friction may accelerate the degradation of the packing material, and therefore require more frequent maintenance to prevent unnecessary emissions. Furthermore, in any case, conventional dynamic seals with pressurized trim (eg, stem packing seals on sliding stem control valves and shaft packing seals on rotary control valves) may still allow some level of fugitive emissions to be released from the control valve.

[0028] As an alternative, metal bellows seals are often used in applications that require minimal leakage of the process fluid to the atmosphere (e.g., involving hazardous process fluids). Metal bellows sealing systems can provide significantly reduced leakage rates (e.g., less than 1x10 -6 Cubic centimeters per second (cc / sec). Conventional metal bellows sealing systems are typically arranged in the valve stem bore, where the metal bellows replaces the dynamic seal around the sliding valve stem as the primary seal and uses a static gasket for sealing. However, when the metal bellows fails due to wear, fugitive emissions immediately increase by several orders of magnitude. Therefore, a dynamic packing system is typically used in conjunction with the metal bellows sealing system, which is downstream of the bellows along the leakage flow path through the valve stem bore to provide additional sealing to prevent fugitive emissions. However, this arrangement tends to be relatively expensive and requires a relatively large bonnet to provide a valve stem bore of sufficient length for both the metal bellows system and the dynamic packing system. In addition, conventional bellows sealing systems can typically only be used for specific operating conditions (e.g., relatively low pressures) and specific types of control valves (e.g., sliding stem valves with relatively short valve stem travel). In addition, as described above, the effectiveness of the dynamic packing system may also decrease over time and result in unacceptable levels of fugitive emissions when the metal bellows eventually fails.

[0029] Examples of the disclosed technology can address these issues, including by providing a packing system for a valve assembly that provides sealing performance from a pressurized valve member comparable to that of a metal bellows system (e.g., in accordance with International Organization for Standardization (ISO) Standard 15848-2, Class A), but without the various disadvantages of the bellows system described above. In this regard, some examples can provide improved sealing in a more compact package than conventional designs and in a configuration that can be used in a wider range of operating conditions (e.g., high pressures, high temperatures) and a wider range of control valves (e.g., rotary valves, sliding stem valves with longer stem travel, and large valves for which metal bellows systems are generally impractical).

[0030] In some examples, a packing system for a valve assembly can utilize a barrier lubricant (e.g., grease or other liquid) between a process fluid and the atmosphere to establish and maintain a specific (e.g., different) pressure drop through different packing groups of the packing system. Some configurations can provide a valve assembly with a packing system, the packing system comprising an upstream (e.g., first or lower) packing group and a downstream (e.g., second or upper) packing group, the upstream packing group and the downstream packing group jointly defining at least a portion of the packing volume between the two packing groups. A port can extend through the valve assembly (e.g., through the valve cover of the valve assembly) and lead to the packing volume of the packing system. A pressurized fluid reservoir (e.g., a barrier lubricant or grease tank) can be connected to the packing volume fluid via the port to pressurize the packing volume. Therefore, the pressure drop on the upstream packing group can be reduced, and as further described below, improved control of emissions can be achieved.

[0031] In some examples, a packing system including a pressurized barrier lubricant reservoir can be easily retrofitted into an existing valve assembly. For example, some existing valve assemblies have a valve cover with a pre-drilled lubrication port that is in fluid communication with the packing volume. In such cases, the tank can be placed in fluid communication with the packing volume via a pre-existing lubrication port to provide a pressurized barrier lubricant within the packing volume. Thus, a large number of field systems can be economically retrofitted, in part because field drilling may not be required. However, in other cases, a valve cover port for connecting to a pressurized fluid source (e.g., a barrier lubricant or grease tank or other reservoir) can be drilled or otherwise formed into an existing valve cover of a valve assembly on site or during manufacturing.

[0032] Some examples can provide enhanced sealing performance and reduced wear on the packing group, including maintaining an elevated pressure differential on the upper packing group at the same time. For example, some exemplary implementations provide a packing system that is configured to provide a barrier lubricant pressure that varies with process pressure within the packing volume. In some examples, the tank chamber of the tank (or other reservoir) is connected to the process pressure fluid via a process channel passing through the valve cover. The process pressure in the tank chamber is added to the piston spring of the tank to provide a barrier lubricant pressure that is associated with the process pressure within the packing volume (e.g., providing a fluid pressure that increases from the process pressure or otherwise offsets a constant or variable value within a certain range of process pressure to the valve cover port). In some examples, a spring or other biasing element can be selected to supplement the pressure of the process fluid according to the compression / extension of the spring (or other energization / relaxation of another biasing element) to provide a specific pressure drop on the packing groups on opposite sides of the corresponding packing volume. Controlling the pressure differential via controlling the barrier lubricant pressure in this way can help optimize (e.g., minimize) the pressure differential across the two packing groups while providing improved sealing performance with lower packing stress applied to the packing groups, which can help maximize the life and sealing performance of the packing groups.

[0033] In some applications, it may be undesirable for barrier lubricant to leak from the packing inter-packing volume of the packing system to the atmosphere. Therefore, in some examples, the packing system can be configured to prevent barrier lubricant from leaking to the atmosphere through the downstream packing group in addition to controlling fugitive emissions from the packing system. In some cases, the packing system can be configured to achieve a reverse pressure drop (i.e., the pressure drop relative to the flow in the leakage direction of the conventional packing system is reversed) through the packing group of the packing system. Therefore, the flow of the barrier lubricant can be directed inward toward the process fluid instead of reaching the atmosphere along the leakage path. In some examples, the packing system may include a first (e.g., lower) packing group, a second (e.g., middle) packing group, and a third (e.g., upper) packing group, wherein the lower packing group and the middle packing group define a first (e.g., lower) packing inter-packing volume and the middle packing group and the upper packing group define a second (e.g., upper) packing inter-packing volume. A first pressure reservoir (i.e., a barrier lubricant reservoir or tank) may be in fluid communication with the first inter-packing volume and the process pressure, and a second pressure reservoir may be in fluid communication with the second inter-packing volume and the process pressure. The second pressure reservoir may be configured to provide a second barrier lubricant pressure greater than the first barrier lubricant pressure provided by the first pressure reservoir, which may result in potential leakage of the barrier lubricant within the second inter-packing volume being directed upstream (relative to normal leakage flow) to the first inter-packing volume.

[0034] In some applications, potential process contamination due to leakage of barrier lubricant into the process fluid may also (or alternatively) be undesirable. Therefore, in some examples, the packing system can be configured to greatly reduce or even eliminate process contamination that would otherwise be caused by leakage of barrier lubricant from the packing system into the process fluid. For example, some configurations can pressurize the process fluid into the upstream packing inter-volume along the potential leak path so that the process fluid, rather than the barrier lubricant, can leak back into the process flow. Various downstream packing arrangements can then be used to prevent leakage from the upstream packing inter-volume (with pressurized process fluid), including as discussed above and below in various ways.

[0035] In some specific examples, the packing system can include a first (e.g., lower) packing group, a second (e.g., lower-middle) packing group, a third (e.g., upper-middle) packing group, and a fourth (e.g., upper) packing group that define a first (e.g., lower) packing volume, a second (e.g., middle) packing volume, and a third (e.g., upper) packing volume. A first pressure reservoir (e.g., a low-pressure barrier lubricant reservoir or tank) can be in fluid communication with the second packing volume and the process pressure to provide a first barrier lubricant pressure, and a second pressure reservoir (e.g., a high-pressure barrier lubricant reservoir or tank) can be in fluid communication with the third packing volume and the process pressure to provide a second barrier lubricant pressure greater than the first barrier lubricant pressure. A pump can be in fluid communication with the first packing volume and the process flow to provide a process fluid at an elevated pressure to the first packing volume. The first pressure reservoir can provide pressurized fluid to the second packing volume at a pressure lower than the pressure of the process fluid in the first packing volume. In addition, the second pressure reservoir can provide pressurized fluid to the third packing volume at a higher pressure than the pressure provided in the second packing volume. Therefore, leakage of pressurized process fluid from the first packing volume can proceed in both directions along the leakage flow path (i.e., upstream to the process flow and downstream to the second packing volume). Thus, for example, barrier lubricant can be completely prevented from leaking from the second packing volume into the process flow, and fugitive emissions from the first packing volume can be effectively remedied by the pressurized second and third packing volumes. In addition, any process fluid that leaks from the first packing group through the first packing group into the process flow can typically be returned to the valve cover by the pump.

[0036] Examples of the disclosed technology may also provide a packing system for a valve assembly, the packing system having a packing diagnostic system, including an indication that the packing system (or one or more packing groups thereof) requires maintenance or requires replacement. For example, the packing diagnostic system may be configured to evaluate the sealing performance or other health indicators of the packing system (or one or more packing groups of the packing system) by monitoring the level of barrier lubricant in one or more packing inter-volumes of the packing system. In some examples, the packing diagnostic system may indicate a maximum threshold barrier lubricant volume accumulated in one or more pressure reservoirs of the packing system, the maximum threshold barrier lubricant volume being caused by leakage of barrier lubricant from different packing inter-volumes. Alternatively, the packing diagnostic system may indicate a minimum threshold barrier lubricant volume in the packing inter-volume, the minimum threshold barrier lubricant volume being caused by leakage of barrier lubricant from the specific packing inter-volume. In some examples, the packing diagnostic system may be configured to monitor a pump duty cycle or other characteristics of a pump of the packing system, the pump being configured to provide pump pressure to one or more packing inter-volumes of the packing system.

[0037] An example of the disclosed technology may also provide a method for retrofitting a packing system of a valve assembly, including a packing system as described above. For example, the method may include placing a pressure reservoir having a pressurized barrier lubricant in fluid communication with the packing inner volume of the valve assembly. Some existing valve assemblies have a valve cover with a pre-drilled lubrication port, which is in fluid communication with the packing volume. Therefore, in such cases, a pressure reservoir (or other reservoir) may be placed in fluid communication with the packing volume via the lubrication port to provide a pressurized barrier lubricant in the corresponding packing volume. In other cases, one or more valve cover ports may be drilled into the existing valve cover of the valve assembly, and one or more pressure reservoirs (or other reservoirs) may be placed in fluid communication with one or more packing volumes of the valve assembly. In some other cases, one or more process channels may be drilled into the existing valve cover of the valve assembly to place one or more pressure reservoirs in fluid communication with the process pressure of the valve assembly (e.g., to ensure that the packing pressure exceeds the process pressure).

[0038] The principles of the present disclosure are applicable to various types of valve assemblies, such as sliding stem control valves and rotary shaft control valves, as well as various packing arrangements, such as jam-style or live-loaded, and various packing materials, such as polytetrafluoroethylene (PTFE) and graphite.

[0039] Reference now Figure 1 and Figure 2 , shows an example of the valve assembly 100. Specifically referring to Figure 1, the valve assembly 100 is a sliding stem type control valve having a packing system according to the principles of the present disclosure. Figure 1 The illustrated portion of the valve assembly 100 in FIG. 1 includes a bonnet 102 mounted on a valve body 104 and an operating member, illustrated as a sliding valve stem 106, extending along a central axis 110 through a valve stem aperture 108 formed in the bonnet 102. Fasteners 112 may be used to removably secure the bonnet 102 to the valve body 104. A valve flow passage 114 extends through the valve body 104 between an inlet 116 and an outlet 118 and provides a path for a process fluid to flow through the valve assembly 100. The process fluid may be any liquid or gas, including steam, water, natural gas, oil, or other chemical compounds. The valve flow passage 114 is opened and closed by a control member 120, which may be moved between a closed position and an open position by the sliding valve stem 106 within a cage 122, which is disposed within the valve flow passage 114. One end of the cage 122 contacts the valve seat 124, and the other end of the cage 122 engages a guide 126 disposed on the bottom side of the valve cover 102 concentric with the central axis 110 (see FIG. Figure 2 ), such that the cage 122 is partially disposed within a guide 126 of the bonnet and partially disposed within an opening 128 of the valve body 104 .

[0040] When the valve assembly 100 is in the closed position, especially if Figure 1 As shown, the control member 120 sealingly engages the valve seat 124 to prevent process fluid from passing through the valve assembly 100. In the open position (not shown), the control member 120 is lifted from the valve seat 124 to allow process fluid to pass from the inlet 116 through the hole 130 (or other window) of the cage 122 to the outlet 118. Movement of the control member 120 is achieved by coupling the control member 120 to an actuator (not shown) via the sliding valve stem 106. The actuator controllably moves the sliding valve stem 106 linearly in an upward and downward direction along the central axis 110 of the valve stem bore 108, thereby causing the control member 120 to move between the open position and the closed position and other intermediate positions.

[0041] Still refer to Figure 1 and Figure 2, an example packing system 132 of the valve assembly 100 includes a bonnet 102, a first lower (upstream) packing set 138 disposed in a first lower portion of a valve stem bore 108 around a first lower portion of a sliding valve stem 106, and a second upper (downstream) packing set 140 disposed in a second upper portion of the valve stem bore 108 around a second upper portion of the sliding valve stem 106. Typically, mechanical force can be used to compress the packing sets 138, 140 together to ensure proper sealing performance. For example, in the example shown, a series of packing nuts 134 are threaded onto corresponding packing studs 136 to adjust the load on the packing sets 138, 140 within the valve stem bore 108 and around the sliding valve stem 106.

[0042] In the example shown, the first packing set 138 and the second packing set 140 define an inter-packing volume 142 within the valve stem bore 108 relative to flow along a leakage flow path from the interior of the valve body 104 through the valve cover 102 to the atmosphere (e.g., as shown, axially located between the first packing set 138 and the second packing set 140 along the axial direction of the valve stem 106). Figure 2 , the first packing group 138 includes a first lower ring 146a, a second intermediate ring 146b, and a third upper ring 146c. The rings 146a, 146b, 146c can be formed of PTFE material or any other suitable synthetic resin polymer. In the example shown, the intermediate ring 146b is a V-shaped ring (i.e., having a "V" shaped cross-sectional profile), which is arranged to be oriented upward (i.e., its annular recess faces upward toward the internal packing volume 142), the upper ring 146c is a male adapter received in the annular recess of the intermediate ring 146b, and the lower ring 146a is a female adapter that receives the annular protrusion of the intermediate ring 146b. In some examples, two or more of the rings 146a, 146b, 146c of the first packing group 138 may have similar cross-sectional profiles. In some examples, a carbon bushing may be provided at each end of the first packing group 138 (i.e., adjacent to the lower ring 146a and the upper ring 146c). In some examples, the first packing set 138 can include a single ring, two rings, or four or more rings. In some examples, a packing base insert 144 can be disposed between the first packing set 138 and the valve body 104 within the valve stem bore 108 to provide an optimized sealing surface or material for the lower ring 146a of the first packing set 138.

[0043] Similarly, continue to refer to Figure 2, the second packing group 140 includes a first lower ring 150a, a second intermediate ring 150b, and a third upper ring 150c. The rings 150a, 150b, 150c of the second packing group 140 can be formed of PTFE material or any other suitable synthetic resin polymer. In the example shown, the intermediate ring 150b is a V-shaped ring arranged to be oriented downward (i.e., its annular recess faces downward to the packing volume 142), the lower ring 150a is a convex adapter received in the annular recess of the intermediate ring 150b, and the upper ring 150c is a concave adapter that receives the annular protrusion of the intermediate ring 150b. In some examples, two or more of the rings 150a, 150b, 150c of the second packing group 140 may have similar cross-sectional profiles. In some examples, a carbon bushing may be provided at each end of the second packing group 140 (i.e., adjacent to the lower ring 150a and the upper ring 150c). In some examples, the second packing set 140 may include a single ring, two rings, or four or more rings.

[0044] As discussed in more detail below, the inversion of the first packing set 138 relative to the second packing set 140 can provide specific functional benefits to the packing system 132, compared to conventional packing systems in which both the upper and lower packing sets are generally arranged in a downward orientation (i.e., with their V-rings arranged opposite the leakage flow path). In some examples, one or both of the packing sets 138, 140 can include one or more mechanical seals that are pressure-energized.

[0045] The packing groups 138, 140 and other packing groups discussed below are shown in specific configurations in the various figures. In other examples, other configurations of specific packing groups are possible, including various known configurations for stacking packing rings or other packing materials / arrangements used to reduce leakage through sliding or rotating valve components. Therefore, the examples presented in the figures should be understood to be applicable to other types of packings arranged to have a similar effect on fluid pressure drop.

[0046] To provide improved overall performance, as also generally discussed above, the first packing set 138 and the second packing set 140 together define a packing inter-volume 142 within the valve stem bore 108. For example, in particular, Figure 2 As shown, the packing groups 138, 140 are separated from each other by a spacer, which thus also partially defines the inter-packing volume 142. In the example shown, in particular, the spacer is a support ring 154 (i.e., a "lantern ring" known in the art) that is disposed around the sliding valve stem 106 and within the inter-packing volume 142. In other cases, other flow volumes for the inter-packing volume may be defined in other ways, including by features of the upstream or downstream packing groups or by mechanical spacers configured in other ways.

[0047] Still refer to Figure 2 , the packing follower 164 is partially disposed above the second packing set 140 within the valve stem bore 108. A series of disc springs 172 (e.g., Belleville springs) are slidably mounted around the sliding valve stem 106, with one end of the disc spring 172 in contact with the packing follower 164 and the other end of the disc spring 172 in contact with the packing flange 174. The packing stud 136 and the sliding valve stem 106 pass through corresponding apertures in the packing flange 174. After the first packing set 138 and the second packing set 140 are assembled within the valve stem bore 108 and around the sliding valve stem 106, the packing nut 134 on the packing stud 136 is tightened so that the packing flange 174 transfers the nut load to the disc spring 172. The disc spring 172 is compressed as the packing nut 134 is continuously tightened so as to maintain the spring load on the first packing set 138 and the second packing set 140 through the packing follower 164. The compression of the rings 146a, 146b, 146c, 150a, 150b, 150c of the first packing set 138 and the second packing set 140 causes them to sealingly engage the sliding valve stem 106 and the inner wall of the valve stem bore 108. In some examples, in addition to or in place of the packing follower 164 and the disc spring 172, other known components or arrangements of components may be included in the valve assembly 100 to compress the rings 146a, 146b, 146c, 150a, 150b, 150c of the first packing set 138 and the second packing set 140, as described above.

[0048] Continue to refer Figure 1 and Figure 2 , the valve cover 102 of the valve assembly 100 of the present disclosure includes a first port configured as a valve cover port 176, which extends through the upper portion of the valve cover 102 and into the packing volume 142, so that the valve cover port 176 is in fluid communication with the packing volume 142 within the valve stem bore 108. The valve cover port 176 can be, for example, a cylindrical passage of varying diameter extending between the valve stem bore 108 and the exterior of the valve cover 102, so that one end of the valve cover port 176 opens to the packing volume 142 within the valve stem bore 108 and the other end of the valve cover port 176 opens to the exterior of the valve assembly 100. In particular, the valve cover port 176 can be relatively close to the leakage flow path 180 (see Figure 1 ) leads to an inter-packing volume 142 between the first packing set 138 and the second packing set 140, the leakage flow path generally extending from the valve flow passage 114 in a direction along the central axis 110 and through the second packing set 140. In some cases, the bonnet port 176 can be aligned with a middle portion of the support ring 154 so that the bonnet port 176 is directly in communication with the inter-packing volume 142 at least partially defined by the support ring 154.

[0049] In some examples, a pre-existing lubrication port of the valve assembly can be utilized as the valve cover port 176. Lubrication ports are included on many valve assemblies (including conventional control valves) for the purpose of introducing lubricant into the bore to reduce sliding friction between the sliding valve stem and the packing system. Therefore, some valve assemblies can be equipped (or retrofitted) with a packing system according to the principles of the present disclosure without substantially changing the design or configuration of the valve assembly, including by configuring the retrofitted packing system to define an inter-packing volume between the upstream packing group and the downstream packing group, the inter-packing volume being appropriately in fluid communication with the pre-existing lubrication port.

[0050] exist Figure 1 In the example shown, and as described above, the valve assembly 100 is a stem-guided control valve having an "upward flow" configuration. In the "upward flow" configuration, the valve assembly 100 is capable of throttling the flow of a process fluid through the valve flow passage 114 between an open position and a closed position with a relatively high pressure drop (such as, for example, a pressure drop in excess of 1,000 pounds per square inch differential ("psid") applied in the "upward flow" direction). In this configuration, when the sliding valve stem 106 is in the closed position (such as Figure 1 108 ), the upstream pressure (P1) at the inlet volume 194 near the inlet 116 of the valve body 104 (i.e., the process pressure when the sliding valve stem is in the open position) passes through the plurality of balancing holes 198 of the control member 120 to act on the first packing set 138 of the packing system 132. The first packing set 138 provides a seal or other significant pressure drop between the inter-packing volume 142 of the valve stem bore 108 to substantially prevent leakage, as generally discussed above.

[0051] As discussed above, in order to counteract leakage on the packing system 132 from the upstream pressure P1, the packing follower 164 is configured to apply a force on the packing system 132 in an axial direction along the central axis 110 of the valve stem bore 108. However, as also discussed above, an increase in packing pressure can result in increased friction with the sliding valve stem 106, reduced efficiency, and shortened component life. For the reasons discussed above and other reasons that will be apparent to those skilled in the art, the packing system 132 provided by the example valve assembly 100 can help counteract these negative effects while also reducing overall leakage compared to conventional systems.

[0052] Generally, according to aspects of the present disclosure, a packing system may include a packing-based sealing system that utilizes a barrier lubricant disposed in a packing inter-volume to provide a fluid barrier between a valve flow channel and the surrounding environment, the fluid barrier providing increased sealing performance compared to conventional packing systems. Various types of barrier lubricants may be utilized to provide the aforementioned benefits. In particular, any type of fluid having a molecular size larger than the molecular size of a given process fluid may be used as a barrier lubricant. In addition to providing a fluid barrier, the barrier lubricant may also be configured to provide lubrication between a valve stem of a valve assembly and one or more packing groups of a packing system (e.g., such as between the sliding valve stem 106 of the valve assembly 100 and the packing groups 138, 140 of the packing system 132). For example, in some implementations, the barrier lubricant may be a liquid, such as a grease or oil (e.g., a synthetic grease or oil such as perfluoropolyether (PFPE) and polytetrafluoroethylene (PTFE)). In other implementations, the barrier lubricant may be a gas. In some implementations, the packing system may utilize two or more barrier lubricants having one or more different properties.

[0053] Reference again Figure 1 and Figure 2 In the example shown, a barrier lubricant (L) (e.g., grease) is injected into the inter-packing volume 142 under pressure via the valve cover port 176 to be contained within the inter-packing volume 142 defined by the first packing group 138 and the second packing group 140. The barrier lubricant L can be replenished and pressurized within the inter-packing volume 142 by a tank 200 (e.g., a pressurized barrier lubricant reservoir) or other pressurized fluid source (e.g., other reservoir) located outside the valve cover 102 and in fluid communication with the valve cover port 176. In particular, the tank 200 has a tank body 202 defining a tank chamber 204 and a tank port 206 extending from the tank body 202. The tank port 206 defines a tank passage 210 in fluid communication with the tank chamber 204. In the example shown, the tank port 206 is attached (e.g., threadedly attached) to the bonnet port 176 such that the tank chamber 204 is in fluid communication with the inter-packing volume 142 via the tank passage 210 and the bonnet port 176. In various other examples, including variations of the systems discussed with respect to other figures, various other sources of pressurized barrier lubricant L (i.e., in addition to the tank shown) may be used as appropriate.

[0054] The tank 200 or other reservoir may be variously configured to pressurize and maintain the pressure P2 of the barrier lubricant L within the inter-packing volume 142 at or above the first pressure. Figure 2, the tank 200 includes a tank piston 214 disposed in the tank chamber 204, the tank piston can be linearly displaced between one end of the tank chamber 204 adjacent to the tank passage 210 and the other end opposite to the tank passage 210 in the tank chamber 204, and is biased toward the tank passage 210 by a piston spring 216. Therefore, in the example shown, the tank piston 214 is spring-biased, but can be configured in other ways to pressurize and maintain the pressure of the barrier lubricant L in the tank chamber 204. In some examples, the tank port 206 can be fluidly connected to the valve cover port 176 via an external pipe (not shown) connected to the valve cover port 176 and the tank port 206. In some examples, the tank body 202 can also include a tank inlet 218, which can be configured to add or replenish the barrier lubricant L to the tank chamber 204 while not allowing the barrier lubricant L to leave the tank chamber 204 (for example, to replenish the barrier lubricant L leaking from the packing inter-volume 142 during the continuous operation of the valve assembly 100).

[0055] Specifically refer to Figure 2 During operation of the valve assembly 100, a volume of barrier lubricant L may be disposed within each of the inter-packing volume 142 of the valve stem bore 108, the valve cover port 176, the tank passage 210, and the tank chamber 204. The tank 200 may be configured to maintain a fluid barrier pressure P2 of the barrier lubricant L within the inter-packing volume 142 of the valve stem bore 108 (e.g., via a piston spring 216 or selection of a surface area of ​​a piston head of the tank piston 214).

[0056] In some examples, to reduce fugitive emissions from the packing system 132, the fluid barrier pressure P2 may be maintained (eg, via the tank 200) above the pressure of the process fluid within the valve flow passage 114 of the valve body 104 (eg, the upstream pressure P1 (see Figure 1 )). This can help ensure that the barrier lubricant L within the inter-packing volume 142 leaks upstream into the valve flow channel 114 along the leakage flow path 180, rather than the process fluid leaking downstream along the leakage flow path 180 through the first packing set 138 (and then leaking to the atmosphere via the second packing set 140). More specifically, relative to the flow exiting the valve body 104 along the leakage flow path 180, a negative pressure differential across the first packing set 138 is provided to drive the barrier lubricant L to leak from the inter-packing volume 142 into the process fluid, and a positive pressure differential across the second packing set 140 is provided to drive the barrier lubricant L to leak from the inter-packing volume 142 to the atmosphere, rather than the process fluid. In this regard, as briefly discussed above, the inversion of the first packing set 138 in an upward orientation relative to the second packing set 140 in a downward orientation can help minimize both leakage of the barrier lubricant L into the valve flow channel 114 through the first packing set 138 and leakage to the atmosphere through the second packing set 138.

[0057] In this regard, Figure 3 3 is a graph 300 showing packing pressure differentials as a function of process pressure of a process fluid within the valve flow passage 114. In particular, the graph 300 includes a first line 310 corresponding to a first packing pressure differential (∆P1) across the first packing set 138 (i.e., process pressure P1 minus fluid barrier pressure P2), and a second line 310 corresponding to a second packing pressure differential (∆P2) across the second packing set 140 (i.e., fluid barrier pressure P2 minus atmospheric pressure P2). atm ). In this particular example, the valve assembly 100 has a maximum process pressure P1 of 1,500 pounds per square inch ("psi"), and the canister 200 of the packing system 132 is configured to maintain a fluid barrier pressure P2 of 2,000 psi within the inter-packing volume 142 (e.g., via the piston spring 216).

[0058] like Figure 3 As shown, when the process pressure P1 is 0 psi and the fluid barrier pressure P2 is 2,000 psi, the first packing differential pressure ∆P1 through the first packing group 138 is -2,000 psi. The first packing differential pressure ∆P1 has a positive correlation with the process pressure P1 because the first packing differential pressure ∆P1 increases as the process pressure P1 increases. On the other hand, when the process pressure P1 increases toward 1,500 psi, the second packing differential pressure ∆P2 remains at 2,000 psi. Because the fluid barrier pressure P2 is maintained at a pressure (e.g., 2,000 psi) that is always higher than the process pressure P1 (e.g., a maximum of 1,500 psi), the barrier lubricant L may leak through the first packing group 138 into the valve flow passage 114 of the valve body 104 (see Figure 1 ), but this arrangement almost completely prevents process fluid from leaking through the first packing set 138 into the inter-packing volume 142 (or leaking to the atmosphere through the second packing set 140).

[0059] In some examples, the packing system 132 of the valve assembly 100 may include a sensor arrangement 220 having one or more sensors 220a configured to sense the flow of barrier lubricant L to the valve cover port 176; and a control system 222, the control system being configured to receive signals from the sensor arrangement to determine the leakage of barrier lubricant L from the packing space volume 142 of the valve cover 102. In some examples, the sensor of the sensor arrangement 220 may be included on the tank 200 and may be configured to sense the fluid barrier pressure P2 or other pressure (e.g., such as a pressure gauge or a transmitter). Generally, the leakage rate (or other factors) of one or more packing groups of the packing system may provide an indication of the variable leakage rate of the packing system. In some cases, such a leakage rate may indicate a degradation of sealing performance over the life cycle of the packing system. Therefore, it may be useful to determine the leakage rates of various packing groups (e.g., as discussed above or in other examples below) to support various diagnostic and maintenance operations.

[0060] In some examples, a pressurized reservoir of barrier lubricant L (eg, tank 200) may supplement or even obviate one or more components of a conventional spring-loaded packing system. Figure 1 The packing system 132 of the valve assembly 100 of the present invention, the can 200 that provides the fluid barrier pressure P2 within the packing inter-volume 142 may not need to use the disc spring 172, which is compressed on the packing flange 174 by the packing nut 134 to maintain the spring load on the first packing group 138 and the second packing group 140 through the packing follower 164, so that the rings 146a, 146b, 146c, 150a, 150b, 150c sealingly engage the inner wall of the valve stem 106 and the valve stem hole 108. More specifically, as opposed to the spring-assisted loading provided by the disc spring 172, the can 200 can provide an alternative form of live loading for both the packing groups 138, 140. Therefore, some examples can provide improved sealing performance of the packing system 132 in response to temperature fluctuations, wherein the cost of the valve assembly 100 is reduced overall due to the reduction or elimination of the spring 172. Thus, in some examples, the packing system 132 of the valve assembly 100 may include only the canister 200 (or other source of pressurized barrier lubricant L) and not the disc springs 172 .

[0061] In some examples, the devices or systems disclosed herein (e.g., valve assemblies or packing systems thereof) may be utilized, manufactured, or installed using methods that embody aspects of the disclosed technology. Accordingly, descriptions herein of specific features, capabilities, or intended purposes of a device or system are generally intended to inherently include methods of using such features for the intended purposes, methods of achieving such capabilities, methods of manufacturing related components of such a device or system (or the device or system as a whole), and methods of installing disclosed (or otherwise known) components to support these purposes or capabilities. Similarly, unless otherwise indicated or limited, discussions herein of any methods of manufacturing or using a particular device or system (including installing the device or system) are intended to inherently include disclosure of the utilized features and enabled capabilities of such a device or system as examples of the disclosed technology.

[0062] In this regard, for example, aspects of the present disclosure may include a method for retrofitting an existing valve assembly to include a packing system configured to maintain a fluid barrier pressure within an inter-packing volume of the packing system. Figure 2 and Figure 4 In some cases, an existing lubrication port of a valve cover of an existing valve assembly can be used as a valve cover port (e.g., valve cover port 176, 476) to provide pressurized barrier lubricant L to the packing volume. Thus, in such examples, the valve assembly can be retrofitted to have pressurized barrier lubricant L within the packing volume by placing a can (e.g., can 200, 500) in fluid communication with the lubrication port. In other examples, the valve cover port can be drilled into the existing valve cover of the valve assembly. In addition, with specific reference to Figure 3 In some examples, a process passage (eg, process passage 478 ) may be drilled into an existing bonnet of the valve assembly.

[0063] It is envisaged that the packing system of the valve assembly can be compared with the reference Figures 1 to 3 The exemplary packing system 132 of the valve assembly 100 discussed is configured differently. For example, in some applications, it may be beneficial to minimize the pressure differential across two or more packing groups of the packing system using a pressurized barrier lubricant in one or more inter-packing volumes. In other applications, it may be beneficial to reduce process contamination caused by leakage of barrier lubricant of the packing system into the valve flow passage of the valve assembly. In this regard, reference will be made to Figures 4 to 9 Additional example configurations of packing systems of valve assemblies are described in greater detail.

[0064] In particular, Figure 4 The valve assembly 100 is depicted (see Figure 1) of the exemplary packing system 432. The packing system 432 is similar to the exemplary packing system 132 discussed previously, wherein like elements are indicated by like reference numerals under the "400 and 500 series" reference numerals. For example, the packing system 432 includes a packing system 432 mounted to the valve body 104 (see Figure 1 ) of the valve cover 402, just as the packing system 132 includes the valve cover 102.

[0065] Although the packing system 432 is similar to the packing system 132 in many aspects, there are some different aspects. For example, similar to the packing system 132, the packing system 432 includes a first packing group 438, a second packing group 440, and a tank 500, which is configured to maintain a fluid barrier pressure P2 within a packing volume 442 defined by the first packing group 438 and the second packing group 440 and a support ring 454 arranged within the valve stem hole 408 of the valve cover 402. In addition, the first packing group 438 and the second packing group 440 of the packing system 432 are arranged similarly to the first packing group 138 and the second packing group 140 of the packing system 132, and the tank port 506 of the tank 500 is in fluid communication with the packing volume 442 via the valve cover port 476. However, in contrast to packing system 132, canister 500 of packing system 432 includes process port 530 that communicates with process passage 478 in valve cover 402 to sense relative to leak flow path 180 (see Figure 1 ) at the process pressure P1 at a location upstream of the first packing set 438. Thus, the tank 500 can pressurize the barrier lubricant L within the inter-packing volume 442 (ie, the fluid barrier pressure P2) to a pressure higher than the process pressure P1 (see Figure 1 In other words, the canister 500 of the packing system 432 is configured to ensure that during operation of the valve assembly 100, the fluid barrier pressure P2 remains above the process pressure (e.g., within a predetermined margin or offset) within a certain range of the process pressure P1, with a predetermined margin or offset corresponding to the process pressure P2. Figure 1 and Figure 2 The benefits are similar to those discussed above with respect to the example packing system 132 .

[0066] Specifically refer to Figure 4, the process port 530 of the tank 500 of the packing system 432 is in fluid communication with the tank chamber 504 defined by the tank body 502 of the tank 500. More specifically, the process port 530 is in fluid communication with the variable volume tail space 526 of the tank chamber 504, which is located behind the variable volume head space 528 defined by the piston head 520 of the tank piston 514 of the tank 500. In some examples, the variable volume tail space 526 can be fluidly isolated from the variable volume head space 526, and therefore also fluidly isolated from the packing inter-volume 442 (e.g., such as via one or more sealing members 534 within the tank chamber 504). The tank 500 also includes a piston sleeve 532 disposed within the tank chamber 504, which is configured to slidably receive the piston shaft 522 of the tank piston 514. In the example shown, the piston sleeve 532 slidably receives both the piston spring 516 and the piston shaft 522 of the tank piston 514, so that the piston shaft 522 can be slidably displaced within the piston sleeve 532. In some examples, the piston sleeve 532 can be configured to limit the displacement of the piston head 520 away from the tank port 506, and thus can correspondingly limit the compression of the piston spring 516 and define the maximum volume of the variable volume head space 528 of the tank 500 (i.e., the minimum volume of the variable volume tail space 526). In some examples, the piston sleeve 532 can be configured to be slidably movable within the tank chamber 504 toward the tank channel 510 defined by the tank port 506 to change the maximum or minimum volume of the variable volume tail space 526 and the head space 528.

[0067] Still refer to Figure 4 , the variable volume tail space 526 of the tank chamber 504 is in fluid communication with the process passage 478 of the valve cover 402 via the process port 530. The process passage 478 of the valve cover 402 extends through the outer surface of the valve cover 402 and extends toward the central axis 410 of the valve cover 402 and leads to the hole-type valve stem inlet 446 of the valve stem hole 408, which is provided at the valve flow passage 114 (see FIG. 1 ) of the valve body 104 and the first packing set 438. Figure 1 ). In other words, the hole-type valve stem inlet 446 is located relative to the leakage flow path 180 (see Figure 1 ) is located upstream of the first packing set 438 and is in fluid communication with the valve flow passage 114 of the valve body 104. In the example shown, the process port 530 is in fluid communication with the process passage 478 of the valve cover 402 via the external conduit 536. In some examples, the process port 530 of the canister 500 can be directly secured to the valve cover 402 at the process passage 478 of the valve cover 402.

[0068] As briefly described above, the packing system 432 can assist the piston spring 516 in maintaining the fluid barrier pressure P2 above the varying process pressure P1 by exposing the variable volume tail space 526 of the tank 500 to the process pressure P1. With P2 thus tracking P1, the system 432 can provide a reduced pressure differential across the first packing group 438 and the second packing group 440, thereby correspondingly reducing wear on the first packing group 438 and the second packing group 440 during continued operation of the valve assembly 100. In this regard, Figure 5 The valve body 104 of the valve assembly 100 with the valve cover 402 and the packing system 432 is shown (see Figure 1 ). As with diagram 300, diagram 600 includes a first line 610 corresponding to a first packing pressure differential ∆P1 across a first packing group 438 (i.e., between process pressure P1 and fluid barrier pressure P2), and a second line 610 corresponding to a first packing pressure differential ∆P1 across a second packing group 440 (i.e., between fluid barrier pressure P2 and atmospheric pressure P2). atm In this particular example, the valve assembly 100 has a maximum process pressure P1 of 1,500 psi, and the tank 500 of the packing system 432 is configured to provide a minimum fluid barrier pressure P2 of 500 psi.

[0069] like Figure 5 As shown, when the process pressure P1 is 0 psi and the fluid barrier pressure P2 is at a minimum pressure of 500 psi, the first packing pressure differential ∆P1 through the first packing group 438 is at -500 psi, and the second packing pressure differential ∆P2 through the second packing group 440 is 500 psi. The second packing pressure differential ∆P2 has a positive correlation with the process pressure P1 because the second packing pressure differential ∆P2 increases as the process pressure P1 increases (i.e., due to a corresponding increase in P2). In addition, since the variable volume tail space 526 of the tank chamber 504 is exposed to the process pressure P1 via the process port 530, the second packing pressure differential ∆P2 has a constant offset of 500 psi relative to the process pressure P1 at any given time (i.e., the minimum fluid barrier pressure P2 provided by the piston spring 516). For example, when process pressure P1 is at 800 psi, the second packing differential pressure is at 1,300, and when process pressure P1 is at a maximum of 1,500 psi, the second packing differential pressure ∆P2 is at 2,000 psi. Furthermore, because fluid barrier pressure P2 is maintained at a constant offset of 500 psi relative to process pressure P1, the first packing differential pressure ∆P1 is maintained at -500 psi for any given process pressure P1 between 0 psi and 1,500 psi. Figure 3As discussed, providing a negative first packing pressure differential ∆P1 may cause the barrier lubricant L to enter the valve flow passage 114 from the inter-packing volume 442 through the first packing set 438 (see Figure 1 ), but it also prevents the process fluid from leaking to the atmosphere through the first packing group 438 and the second packing group 440.

[0070] In addition to helping reduce fugitive emissions along leakage flow path 180, Figure 4 The arrangement relative to Figure 2 The arrangement reduces the pressure differentials ∆P1, ∆P2 (and the total pressure differential ∆P2-∆P1) over almost the entire shown range of P1. Such a reduction can significantly reduce friction and wear on the first packing group 438 and the second packing group 440 and increase the overall life of the packing system 432 because the packing groups 438, 440 may not need to be compressed as high as the compression value used to provide the required seal. In addition, the packing system 432 can allow the user to customize the offset or margin between the second packing pressure differential ∆P2 and the process pressure P1 by selecting a specific spring force of the piston spring 516 (which sets the minimum fluid barrier pressure P2) based on the user's preference for prioritizing minimum wear on the packing groups 438, 440 or maximum sealing performance of the packing system 432. Thus, in some examples, the packing system 432 can be configured to provide a second packing pressure differential ∆P2 within a range of approximately 105% to approximately 220%, within a range of approximately 110% to approximately 190%, within a range of approximately 115% to approximately 175%, or within a range of approximately 120% to approximately 150% of the maximum process pressure P1 of the valve assembly 100 .

[0071] As briefly mentioned above, in some applications it may be beneficial to provide a packing system for a valve assembly that can further reduce leakage of barrier lubricant into the valve flow passage while still providing reduced wear on the packing system and preventing fugitive emissions. Figure 6 The valve assembly 100 is depicted (see Figure 1 ) is another example of a packing system 732. The packing system 732 is similar to the example packing systems 132, 432 discussed previously, where like elements are indicated by like reference numerals under the "700 and 800 series" reference numerals. For example, the packing system 732 includes a valve body 104 (see Figure 1 ) of the valve cover 702, just as the packing systems 132, 432 include the valve covers 102, 402, respectively.

[0072] While the packing system 732 is similar in many respects to the example packing systems 132, 432 discussed previously, there are some different aspects. For example, similar to the packing systems 132, 432, the packing system 732 includes a first support ring 754a disposed between a first lower packing set 738 and a second intermediate packing set 740 within the valve stem bore 708 of the valve cover 702, the first support ring defining a first lower packing inter-volume 742a. ​​The first lower tank 800a is in fluid communication with the first packing inter-volume 742a via a first lower valve cover port 776a, and is in fluid communication with the process pressure P1 via a first process passage 778a in the valve cover 702 that is in fluid communication with a first process port 830a of the first tank 800a. However, in contrast to the packing systems 132, 432, the packing system 732 further includes a third upper packing group 782 that is disposed in the valve stem bore 708 around a third portion of the valve stem 106 and is spaced apart from the second packing group 740 by a second support ring 754b that defines a second upper packing inter-volume 742b within the valve stem bore 708. In other words, the first packing group 738 is disposed between the valve body 104 and the second packing group 740, and the second packing group 740 is disposed between the first packing group 738 and the third packing group 782, such that the leakage flow path 180 (see Figure 1 ) from valve flow passage 114 (see Figure 1 ) extends through the first packing group 738 into the first inter-packing volume 742a, through the second packing group 740 into the second inter-packing volume 742b, and then through the third packing group 782 to the atmosphere.

[0073] In the example shown, the first packing group 738 and the second packing group 740 are configured similarly to the first packing group 138 of the packing system 132 (i.e., the rings are arranged in an upward orientation), and the third packing group 782 is configured similarly to the second packing group 140 of the packing system 132 (i.e., the rings are arranged in a downward orientation). Therefore, this particular arrangement of the rings of the packing groups 738, 740, 782 can be particularly beneficial in reducing the leakage of the barrier lubricant L from the second inter-packing volume 742b to the first inter-packing volume 742a or to the atmosphere. In some examples, the second packing group 740 and the third packing group 782 can be configured similarly to each other (i.e., the rings are arranged in a downward orientation). In some examples, each of the packing groups 738, 740, 782 can be configured similarly to each other.

[0074] Still refer to Figure 6, the packing system 732 also includes a second tank 800b, which is in fluid communication with the second packing volume 742b via a second upper valve cover port 776b, which extends through the exterior of the valve cover 702 and opens into the packing volume 742b. The second process port 830b of the second tank 800b is also connected to the valve flow channel 114 (see Figure 1 ) fluid communication. Similar to the first process passage 778a, the second process passage 778b extends through the outer surface of the valve cover 702 toward the central axis 710 of the valve cover 702 and leads to the valve flow passage 114 (see Figure 1 ) between the valve stem hole 708 of the valve stem hole entrance 746. In the example shown, the first tank 800a and the second tank 800b of the packing system 732 are configured similarly to each other and also similarly to Figure 4 The tank 500 of the packing system 432 is shown in FIG. Therefore, the first tank 800a and the second tank 800b include tank bodies 802a and 802b that define tank chambers 804a and 804b, respectively, wherein tank pistons 814a and 814b, piston springs 816a and 816b, and piston sleeves 832a and 832b are respectively arranged in the tank chambers 804a and 804b. Therefore, the first tank 800a is configured to pressurize the barrier lubricant L in the first packing volume 742a to the minimum first fluid barrier pressure (P4) based on the spring force of the first piston spring 816a. Similarly, the second tank 800b is configured to pressurize the barrier lubricant L in the second packing volume 742b to the minimum second fluid barrier pressure (P5) based on the spring force of the second piston spring 816b.

[0075] In the example shown, the first tank 800a is configured to provide a first fluid barrier pressure P4 that is less than a second fluid barrier pressure P5 provided by the second tank 800b (i.e., the first tank 800a is a low-pressure tank, and the second tank 800b is a high-pressure tank). For example, the first piston spring 816a of the first tank 800a may have a spring constant that is less than the second piston spring 816b of the second tank 800b. This particular configuration of the first fluid barrier pressure P4 and the second fluid barrier pressure P5 of the packing system 732 may reduce or eliminate leakage of the barrier lubricant L from the first packing set 738 to the valve flow passage 114 of the valve body 104 of the valve assembly 100 (see Figure 1 As described above, such leakage may be undesirable because, in some cases, even a small amount of barrier lubricant L may contaminate the process fluid flowing through the valve flow passage 114.

[0076] In particular, because the first fluid barrier pressure P4 is relatively low, the pressure differential across the first packing group 738 can also be relatively low. Therefore, even at relatively low compression, the first packing group 738 can highly reliably prevent the barrier lubricant L from escaping from the first gap region 742a. ​​In addition, the relatively high value of the second fluid barrier pressure P5 can further ensure that any leakage on the second packing group 740 is in the upstream direction along the leakage flow path 180 (see Figure 1 ).

[0077] In this regard, Figure 7 The valve body 104 of the valve assembly 100 with the packing system 732 is shown (see Figure 1 ) is a graphical representation 900 of the packing pressure differential as a function of the process pressure within the valve flow passage 114 of the packing system 732. Figure 7 The diagram 900 corresponds to the packing system 132, 432 respectively. Figure 3 and Figure 5 In particular, similar to the diagrams 300 and 600, the diagram 900 includes a first line 910 corresponding to a first packing pressure differential (∆P1) through the first packing group 738 (i.e., between the process pressure P1 and the first inter-packing volume 742a), a second line 920 corresponding to a second packing pressure differential (∆P2) through the second packing group 740 (i.e., between the first inter-packing volume 742a and the second inter-packing volume 742b), and a third line 930 corresponding to a third packing pressure differential (∆P3) through the third packing group 782 of the packing system 732 of the valve assembly 100 (i.e., between the second packing inner volume 742b and the atmosphere).

[0078] In this particular example, the valve assembly 100 has a maximum process pressure P1 of 1,500 psi, the first tank 800a of the packing system 732 is configured to maintain a minimum first fluid barrier pressure P4 of 25 psi within the first inter-packing volume 742a (via the first piston spring 816a), and the second tank 800b of the packing system 732 is configured to maintain a minimum second fluid barrier pressure P5 of 500 psi within the second inter-packing volume 742b (via the second piston spring 816b). In other words, the first tank 800a and the second tank 800b are configured to provide fluid barrier pressures P4, P5, respectively, which track any changes in the process pressure P1 within a predetermined relatively small margin during operation of the valve assembly 100 to provide the benefits discussed below.

[0079] like Figure 7As shown, when the process pressure P1 is 0 psi, the first packing pressure differential ∆P1 through the first packing group 738 is -25 psi, the second packing pressure differential ∆P2 through the second packing group 740 is -500 psi, and the third packing pressure differential ∆P3 through the third packing group 782 is 500 psi. The third packing pressure differential ∆P3 has a positive correlation with the process pressure P1 because the third packing pressure differential ∆P3 increases as the process pressure P1 increases. In addition, at any given time, the third packing pressure differential ∆P3 has a constant offset of 500 psi relative to the process pressure P1 (i.e., the minimum second fluid barrier pressure P5 provided by the second piston spring 816b). For example, when the process pressure is at 800 psi, the third packing pressure differential is at 1,300, and when the process pressure P1 is at a maximum value of 1,500 psi, the third packing pressure differential is at 2,000 psi. Furthermore, because the second fluid barrier pressure P5 is maintained at a constant offset of 500 psi relative to the process pressure P1 (e.g., via the second piston spring 816b), and the first fluid barrier pressure P4 is maintained at a constant offset of 25 psi relative to the process pressure P1 (e.g., via the first piston spring 816a), for any given process pressure P1 between 0 psi and 1,500 psi, the second packing differential pressure ∆P2 is maintained at -500 psi and the first packing differential pressure ∆P1 is maintained at -25 psi.

[0080] Reference again Figure 6 , the first packing volume 742a has a first fluid barrier pressure P4 that is lower than the second fluid barrier pressure P5 of the second packing volume 742b, which permits the barrier lubricant L to leak from the second packing volume 742b through the second packing set 740 and into the first packing volume 742a. ​​Therefore, the first packing volume 742a can be used as a container for the barrier lubricant L to leak from the second packing volume 742b and prevent the barrier lubricant L from leaking through the first packing set 738 to the valve flow channel 114 of the valve body 104 (see Figure 1 More specifically, the first packing pressure difference ΔP1 is minimized to an amount that can prevent the barrier lubricant L from leaking from the first inter-packing volume 742 a into the valve flow channel 114 .

[0081] However, as at least the second packing set 740 wears and the performance of the packing system 732 generally degrades, leakage from the second inter-packing volume 742b to the first inter-packing volume 742a may increase. Therefore, in some examples, the first tank 800a may include a visual indicator (not shown) that may indicate that a threshold maximum volume of the first tank 800a (i.e., a threshold maximum barrier lubricant volume within the first inter-packing volume 742a) has been exceeded due to the accumulation of excess barrier lubricant L within the first inter-packing volume 742a, which may indicate that maintenance or replacement of the packing system 732 is required. For example, in some implementations, the visual indicator may be included on a portion of the piston rod of the first tank piston 814a extending outward from the first tank body 802a. Similarly, in some such examples, in addition to (or as an alternative to) the visual indicator of the first tank 800a, the second tank 802b of the packing system 732 may also include a visual indicator.

[0082] In some examples, the packing system 732 may include a sensor arrangement (not shown) configured to sense the flow of the barrier lubricant L to the valve cover ports 776a, 776b; and a control system (not shown) configured to receive signals from the sensor arrangement to determine leakage of the barrier lubricant L from the first inter-packing volume 742a or the second inter-packing volume 742b of the valve cover 702. For example, in some such implementations, the sensor arrangement of the packing system 732 may include one or more position sensors arranged to sense the position of the tank pistons 814a, 814b relative to the tank bodies 802a, 802b of the tanks 800a, 800b, respectively. In other such implementations, the sensor arrangement of the packing system 732 may include one or more sensors arranged to sense the flow of the barrier lubricant L directly through one or both of the valve cover ports 776a, 776b.

[0083] In some applications (e.g., such as those involving particularly sensitive process fluids), it may be beneficial to configure the packing system of the valve assembly to almost completely prevent leakage of barrier lubricant into the valve flow passage while still providing for reduced wear on the packing system and preventing fugitive emissions. Figure 8 The valve assembly 100 is depicted (see Figure 1 ) is another example packing system 1032. The packing system 1032 is similar to the example packing systems 132, 432, 732 discussed previously, wherein like elements are indicated by like reference numerals under the "1000 and 1100 series" reference numerals. For example, the packing system 1032 includes a valve body 104 (see Figure 1) of the valve cover 1002, just as the packing systems 132, 432, 732 include the valve covers 102, 402, 702, respectively.

[0084] While the packing system 1032 is similar in many respects to the example packing systems 132, 432, 732 discussed previously, there are some different aspects. For example, similar to the packing systems 132, 432, 732, the packing system 1032 includes a first intermediate support ring 1054a disposed between a first middle lower packing group 1038 and a second middle upper packing group 1040 within the valve stem bore 1008 of the valve cover 1002, the first intermediate support ring defining a first intermediate packing volume 1042a. The first lower tank 1100a is in fluid communication with the first packing volume 1042a via a first intermediate valve cover port 1076a, and is in fluid communication with the process pressure P1 via a first process passage 1078a in the valve cover 1002. Similarly, the packing system 1032 also includes a third upper packing group 1082 disposed around a third portion of the valve stem 106 in the valve stem bore 1008 and spaced apart from the second packing group 1040 by a second support ring 1054b that defines a second upper packing inter-volume 1042b. The second upper canister 1100b is in fluid communication with the second packing inter-volume 1042b via the first upper bonnet port 1076b, and is also in fluid communication with the process pressure P1 via a second process passage 1078b in the bonnet 1002.

[0085] However, in contrast to the packing systems 132, 432, 732, the packing system 1032 further includes a fourth lower packing group 1084 disposed around a fourth portion of the valve stem 106 in the valve stem bore and spaced apart from the first packing group 1038 by a third support ring 1054c that defines a third lower packing inter-volume 1042c within the valve stem bore 1008. In other words, the fourth packing group 1084 is disposed between the valve body 104 and the first packing group 1038, and the second packing group 1040 is disposed between the first packing group 1038 and the third packing group 1082, such that the leakage flow path 180 (see Figure 1 ) from the valve flow passage 114 (see Figure 1 ) extends through the fourth packing group 1084 into the third inter-packing volume 1042c, through the first packing group 1038 into the first inter-packing volume 1042a, through the second packing group 1040 into the second inter-packing volume 1042b, and then through the third packing group 1082 to the atmosphere.

[0086] In the example shown, the first packing group 1038 and the third packing group 1082 are configured similarly to the first packing group 138 of the packing system 132 (i.e., the rings are arranged in an upward orientation), and the second packing group 1040 and the fourth packing group 1084 are configured similarly to the second packing group 140 of the packing system 132 (i.e., the rings are arranged in a downward orientation). This particular arrangement of the rings of the packing groups 1038, 1040, 1082, 1084 can be particularly helpful in preventing leakage of the barrier lubricant L from the second inter-packing volume 1042b to the first inter-packing volume 1042a or atmosphere, and preventing leakage from the third inter-packing volume 1042c, for reasons that will be apparent from the discussion below. In some examples, at least the first packing group 1038 and the second packing group 1040 can be configured similarly to each other. In some examples, three or more of the packing groups 1038, 1040, 1082, 1084 can be configured similarly to each other.

[0087] Still refer to Figure 8 The packing system 1032 may also include a pressure intensifier system 1160 that may be configured to provide process fluid to the third packing volume 1042c at an elevated pressure. Figure 8 In the example shown, the booster system 1160 of the packing system 1032 includes a pump 1162 configured to increase or boost the pressure of the process fluid to a pump pressure (P6), a pump actuator 1164 (e.g., a solenoid-actuated valve) configured to permit or prevent flow from an air supply (not shown) to the pump 1162, a pressure transmitter 1166 configured to sense the pump pressure P6 at the pump 1162 (i.e., the output pressure of the pump 1162), and a controller 1168 in electrical communication with the pump actuator 1164 and the pressure transmitter 1166. The controller 1168 can be configured to receive a signal corresponding to the pump pressure P6 from the pressure transmitter 1166 and control the pump actuator 1164 to cause the pump 1162 to increase, decrease, or maintain the pump pressure P6. In some examples, the controller 1168 can communicate wirelessly with the booster system 1160. In some examples, the controller 1168 can be configured to receive a user input that can set a desired pump pressure P6. In some examples, the booster system 1160 may also include a second pressure transmitter (not shown) that may be in electronic communication with the controller 1168 and configured to sense the process pressure P1 (i.e., the input pressure of the pump 1162). In some such examples, the controller 1168 may be configured to automatically adjust the pump pressure P6 based on the signals received from the first pressure transmitter 1166 and the second pressure transmitter.

[0088] Continue to refer Figure 8, the pump 1162 of the intensifier system 1160 is in fluid communication with each of the following: fluid communication with the third packing volume 1042c via the third lower valve cover port 1076c; fluid communication with the process pressure P1 via the first process channel 1078a; and fluid communication with the first variable volume tail space 1126a of the first tank 1100a. In other words, the first process channel 1078a is in fluid communication with both the first variable volume tail space 1126a of the first tank 1100a and the pump 1162, but other configurations are also possible. In the example shown, the pump 1162 is in fluid communication with an air supply (not shown) that drives the pump 1162, with the pump actuator 1164 located between them. Therefore, the pump pressure P6 of the pump 1162 can be controlled relative to the process pressure P1 via the pump actuator 1164. As described above, the pump pressure P6 is provided to the third inter-packing volume 1042c via the third valve cover port 1076c and is therefore confined within the third inter-packing volume 1042c by the first packing group 1038 and the fourth packing group 1084. Thus, in some examples, the pump pressure P6 provided by the pump 1162 can be selected by a user via the controller 1168 controlling the pump actuator 1164 and / or by selecting a piston spring of the pump 1162.

[0089] It should be appreciated that the packing system 1032 may provide a method of further reducing or even completely preventing leakage of the barrier lubricant L from the second packing inter-volume 1042b into the valve flow passage 114 of the valve body 104 (see Figure 1 ) and thus cause process contamination. In this regard, Fig. 9 The valve body 104 of the valve assembly 100 with the packing system 1032 is shown (see Figure 1 ) of the valve flow passage 114 as a function of the process pressure. Fig. 9 The diagram 1200 corresponds to the packing systems 132, 432, 732 respectively. Figure 3 , Figure 5 and Figure 7The diagrams 300, 600, and 900 are similar. In particular, similar to diagrams 300 , 600 , and 900 , diagram 1200 includes a first line 1210 corresponding to a first packing pressure differential (∆P1) through the first packing group 1038 (i.e., between the first packing volume 1042a and the third packing volume 1042c ), a second line 1220 corresponding to a second packing pressure differential (∆P2) through the second packing group 1040 (i.e., between the first packing volume 1042a and the second packing volume 1042b ), a third line 1230 corresponding to a third packing pressure differential (∆P3) through the third packing group 1082 (i.e., between the second packing volume 1042b and atmosphere), and a fourth line 1240 corresponding to a fourth packing pressure differential (∆P4) through the fourth packing group 1084 of the packing system 1032 of the valve assembly 100 (i.e., between the process pressure P1 and the third packing volume 1042c ).

[0090] In this particular example, the valve assembly 100 has a maximum process pressure P1 of 1,500 psi, the first tank 1100a of the packing system 1032 is configured to maintain a minimum first fluid barrier pressure P4 of 25 psi within the first inter-packing volume 1042a (via the first piston spring 1116a), the second tank 1100b of the packing system 1032 is configured to maintain a minimum second fluid barrier pressure P5 of 500 psi within the second inter-packing volume 1042b (via the second piston spring 1116b), and the intensifier system 1160 of the packing system 1032 is configured to maintain a minimum pump pressure P6 (via the pump 1162) within the third inter-packing volume 1042c that is 25 psi greater than any given process pressure P1. In other words, the first tank 1100a and the second tank 1100b are configured to provide fluid barrier pressures P4, P5, respectively, which track any changes in the process pressure P1 within a predetermined relatively small margin during operation of the valve assembly 100, while the booster system 1160 is configured to provide a pump pressure P6 that is boosted relative to the variable process pressure P1 so as to provide the benefits discussed below.

[0091] like Fig. 9 As shown in the diagram 1200, when the process pressure P1 is 0 psi, the first packing differential pressure ∆P1 through the first packing group 1038 is 25 psi, the second packing differential pressure ∆P2 through the second packing group 1040 is -475 psi, the third packing differential pressure ∆P3 through the third packing group 1082 is 500 psi, and the fourth packing differential pressure ∆P4 through the fourth packing group 1084 is -50 psi. Figure 6Similar to the packing system 732 of FIG. 1 , the packing system 1032 is configured such that the third packing differential pressure ∆P3 has a positive correlation with the process pressure P1. In addition, at any given time, the third packing differential pressure ∆P3 has a constant offset of 500 psi relative to the process pressure P1 (i.e., the minimum second fluid barrier pressure P5 provided by the second piston spring 1116b). For example, when the process pressure is at 800 psi, the third packing differential pressure ∆P3 is 1,300, and when the process pressure P1 is at a maximum value of 1,500 psi, the third packing differential pressure ∆P3 is 2,000 psi. Furthermore, because the first fluid barrier pressure P4 is maintained at a constant offset of 25 psi relative to the process pressure P1 (e.g., via the first piston spring 1116a), the second fluid barrier pressure P5 is maintained at a constant offset of 500 psi relative to the process pressure P1 (e.g., via the second piston spring 1116b), and the pump pressure P6 within the third packing volume 1042c is maintained at a constant offset of 50 psi relative to the process pressure P1 (e.g., via the intensifier system 1160), for any given process pressure P1 between 0 psi and 1,500 psi, the first packing differential pressure ∆P1 is maintained at 25 psi, the second packing differential pressure ∆P2 is maintained at -475 psi, and the fourth packing differential pressure ∆P4 is maintained at -50 psi.

[0092] Reference again Figure 8 , when the first fluid barrier pressure P4 is controlled by the first tank 1100a to be always lower than the pump pressure P6 in the third inter-filling volume 1042c controlled by the booster system 1160 (i.e., P4<P6), the barrier lubricant L in the first inter-filling volume 1042a cannot flow along the leakage flow path 180 (see Figure 1 ) leaks upstream into the third packing volume 1042c. In addition, in the event that the pump pressure P6 within the third packing volume 1042c is greater than any given process pressure P1 (i.e., P6>P1), any potential leakage of process fluid through the fourth packing group 1084 flows upstream along the leakage flow path 180 (see Figure 1). Generally, any such leakage can also be quickly pumped back into the third packing volume 1042c via the pump 1162. In other words, the possibility of leakage to the atmosphere along the leakage flow path 180 through the fourth packing group 1084 is greatly reduced or even eliminated, while also avoiding leakage of the barrier lubricant L into the process stream. In addition, because the pump 1162 can generally be operated only when it is necessary to restore the pressure P6 (i.e., in response to a leakage from the third packing volume 1042c determined by the controller 1168), monitoring the duty cycle of the pump 1162 (e.g., in the controller 1168) can indicate that the fourth packing group 1084 is worn and the packing system 1032 may need to be repaired or replaced.

[0093] Continue to refer Figure 8 , any leakage of the process fluid in the third packing volume 1042c through the first packing group 1038 into the first packing volume 1042a can increase the fluid volume in the first tank 1100a. In addition, when the second packing group 1040 wears, the barrier lubricant L in the second packing volume 1042b can flow along the leakage flow path 180 (see Figure 1 ) leaks upstream into the first packing inter-volume 1042a, and may also increase the volume of fluid within the first tank 1100a. Thus, in some examples, the first tank 1100a may include a visual indicator (not shown), as discussed above, to indicate a potential need for maintenance of the packing system 1032. In some such examples, the visual indicator of the first tank 1100a may indicate a failure of one or both of: (i) the first packing group 1038, which results in an excess of process fluid in the first tank 1100a; or (ii) the second packing group 1040, which results in an excess of barrier lubricant L in the first tank 1100a. Thus, regardless of whether the first packing group 1038 or the second packing group 1040 fails, the visual indicator of the first tank 1100a may indicate that the packing system 1032 needs to be repaired or replaced. In some examples, the first tank 1100a may include a tank sensor (not shown) that may be configured to sense a fluid volume within the first tank 1100a and send an electrical signal corresponding to the sensed fluid volume to a fill monitoring system (not shown).

[0094] Therefore, it should be understood that in addition to generally providing increased sealing performance and life of the packing system of the valve assembly (including as described above with reference to Figures 1 to 9In addition to the above, examples of the present disclosure can be beneficial for improving the monitoring of valve assemblies, including determining the current sealing effectiveness of the packing system and pre-identifying potential failures of the packing system. In some examples, the valve assembly disclosed herein can allow tracking of the sealing effectiveness of the packing system over an extended period of time, including helping to predict when the packing system may fail and proactively repairing or replacing the packing system. For example, in some examples, the packing system may include a packing monitoring system that can be configured to actively manage the packing inter-pressure of the packing system and monitor the health of the packing system. In some such examples, the packing monitoring system may include a sensor arrangement configured to sense the flow of fluid to a valve cover port in a valve cover of the valve assembly; and a control system configured to determine the leakage of barrier lubricant in one or more packing inter-volumes of the packing system. In some such examples, the packing monitoring system may be external to the valve assembly and may be connected to the valve cover interface of the valve assembly using pipes and fittings.

[0095] As discussed above, aspects of the present disclosure may include methods for retrofitting an existing valve assembly with a packing system configured to maintain one or more fluid barrier pressures (and / or pump pressures) within one or more packing inter-volumes of the packing system. Figure 6 and Figure 8 In some cases, an existing lubrication port of a valve cover of an existing valve assembly can be used as a valve cover port (e.g., one of valve cover ports 776a, 776b, 1076a, 1076b, 1076c). Thus, in such examples, the valve assembly can be retrofitted to have a pressurized barrier lubricant in the inter-packing volume by placing a pressure reservoir (e.g., tank 800a, 800b, 1100a, 1100b) in fluid communication with the lubrication port, or to have an elevated process pressure (e.g., pump pressure P6) in the inter-packing volume by placing a pump (e.g., pump 1162 of intensifier system 1160) in fluid communication with the lubrication port. In other examples, one or more valve cover ports can be drilled into an existing valve cover of a valve assembly. Furthermore, in some examples, a process passage (eg, one or both of process passages 778a, 778b, 1078a, 1078b) may be drilled into an existing bonnet of the valve assembly.

[0096] Although an example packing arrangement has been described in conjunction with a control valve, the scope of the present disclosure is not limited to this implementation. A variety of devices including a movable operating member (e.g., a rotating shaft or a sliding shaft) that provides a seal for a leakage path can be improved by the packing arrangement of the present disclosure. As a specific example, in some implementations, the packing arrangement of the present disclosure can be included as a sealing arrangement in a rotary machine (e.g., such as a rotary screw compressor) to provide a seal between a shaft configured to rotate one or more rotating elements and the surrounding environment to prevent fugitive discharge of a fluid (e.g., a gas) from a shaft hole.

[0097] In some examples, aspects of the disclosed technology (including computerized implementations of methods according to the present disclosure) can be implemented as systems, methods, devices, or articles of manufacture using standard programming or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a control device such as a processor device, a computer (e.g., a processor device operably coupled to a memory), or another electronically operated controller to implement the various aspects detailed herein. Thus, for example, various aspects of the present disclosure can be implemented as an instruction set tangibly embodied on a non-transitory computer-readable medium, such that a processor device can implement instructions based on reading instructions from the computer-readable medium. Some implementations of the disclosed technology can include (or utilize) a control device, such as an automation device, a special-purpose or general-purpose computer, including various computer hardware, software, firmware, etc., consistent with the discussion below.

[0098] The term "article of manufacture" as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier (e.g., non-transitory signal), or medium (e.g., non-transitory medium). For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs), etc.), smart cards, and flash memory devices (e.g., cards, sticks, etc.). In addition, it should be understood that a carrier wave may be employed to carry computer-readable electronic data, such as data used to transmit and receive e-mail or to access a network such as the Internet or a local area network (LAN). Those skilled in the art will recognize that many modifications may be made to these configurations without departing from the scope or spirit of the claimed subject matter.

[0099] Certain operations according to the methods of the present disclosure or systems performing these methods may be schematically represented in the accompanying drawings or otherwise discussed herein. Unless otherwise specified or limited, specific operations represented in a particular spatial order in the accompanying drawings may not necessarily require that these operations be performed in a specific order corresponding to the specific spatial order. Accordingly, certain operations represented in the accompanying drawings or otherwise disclosed herein may be performed in an order different from the order explicitly shown or described, depending on the circumstances of the specific implementation of the disclosed technology. In addition, in some implementations, certain operations may be performed in parallel, including by dedicated parallel processing devices or separate computing devices configured to interoperate as part of a larger system.

[0100] As used herein in the context of computer implementations, unless otherwise specified or limited, the terms "component," "system," "module," and the like are intended to cover part or all of a computer-related system including hardware, software, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to, a processor device, a process executed (or executable) by a processor device, an object, an executable file, an execution thread, a computer program, or a computer. By way of illustration, both an application running on a computer and a computer may be a component. One or more components (or systems, modules, and the like) may reside within an executing process or thread, may be located on one computer, may be distributed between two or more computers or other processor devices, or may be included within another component (or system, module, and the like).

[0101] Also as used herein, unless otherwise limited or defined, "or" represents a non-exclusive list of components or operations that can exist in any variety of combinations, rather than an exclusive list of components that can exist only as alternatives to each other. For example, a list of "A, B, or C" indicates the following options: A; B; C; A and B; A and C; B and C; and A and B and C. Accordingly, the term "or" as used herein is intended to indicate exclusive alternatives only when preceded by an exclusive term such as "any," "one," "only one," or "exactly one." For example, a list of "one of A, B, or C" indicates the following options: A, but not B and C; B, but not A and C; and C, but not A and B. A list that begins with "one or more" (and variations thereof, e.g., "at least one") and includes "or" to separate the listed elements represents an option of one or more of any or all of the listed elements. For example, the phrases "one or more of A, B, or C" and "at least one of A, B, or C" indicate the following options: one or more A; one or more B; one or more C; one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C. Similarly, a list beginning with "plurality" (and variations thereof) and including "or" to separate the listed elements indicates the option of multiple instances of any or all of the listed elements. For example, the phrases "plurality of A, B, or C" and "two or more of A, B, or C" indicate the following options: A and B; B and C; A and C; and A, B, and C.

[0102] As also used herein, "leakage rate" and its variants refer to the mass flow of leakage along the path from the inlet of the valve assembly to the surrounding area, in particular through the packing system or part thereof. For example, "leakage rate" may refer to the total mass flow of leakage through two (or more) packing arrangements of the packing system, which are arranged in series along a common leakage path from the inlet of the valve assembly to the surrounding area. Therefore, a packing system with a "higher leakage rate" and its variants generally allows a higher mass flow rate from the valve inlet through the packing system than a packing system with a "lower leakage rate". Similarly, for example, a "first leakage rate" may refer to a first mass flow leaked through a first packing group of the packing system, a "second leakage rate" may refer to a second mass flow leaked through a second packing group of the packing system arranged in series along the common leakage path of the packing system, and the total "leakage rate" of the packing system may refer to the total mass flow leaked through the first packing group and the second packing group of the packing system. Therefore, the first packing group may have a "first leakage rate" that is different from the "second leakage rate" of the second packing group. Additionally, the use of "fugitive emissions" and variations thereof herein means leakage from the packing system to the atmosphere surrounding the valve assembly.

[0103] As described herein, examples of the disclosed technology can provide a packing system for a valve assembly, which packing system has improved sealing performance in particular. The previous description of the exemplary implementation is provided to enable any person skilled in the art to make or use the disclosed technology. Various modifications of these exemplary implementations will be readily apparent to those skilled in the art without departing from the spirit or scope of the present disclosure, and the general principles defined herein can be applied to other implementations. Therefore, the present disclosure is not intended to be limited to the examples shown herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A packing system for use with a valve, the valve comprising a valve body having an inlet, an outlet, and a flow passage extending between the inlet and the outlet, the packing system comprising: a valve cover configured to be connected to the valve body; a valve stem bore extending through the valve cover to open into the valve body for receiving a valve stem of the valve so that the valve stem can move within the valve stem bore to control flow through the flow passage; a first packing set disposed in the valve stem bore to surround a first portion of the valve stem; a second packing set disposed in the valve stem bore to surround a second portion of the valve stem, wherein the first packing set is between the second packing set and the valve body, and wherein the second packing set is spaced apart from the first packing set by a support ring to define an inter-packing volume within the valve stem bore; and A pressurized barrier lubricant reservoir is in fluid communication with the inter-packing volume via a bonnet port in the bonnet to pressurize a barrier lubricant within the inter-packing volume to be at or above a first pressure.

2. The packing system of claim 1, wherein the pressurized barrier lubricant reservoir is secured to the valve cover at the valve cover port.

3. The packing system of claim 1 , wherein the pressurized barrier lubricant reservoir is arranged to sense a process pressure at a location upstream of the first packing set relative to a leakage flow path from the flow passage through the valve stem bore to pressurize the barrier lubricant above the process pressure.

4. The packing system of claim 3, wherein the pressurized barrier lubricant reservoir comprises: a spring biased piston arranged to compress the barrier lubricant chamber; an outlet port arranged to connect the barrier lubricant chamber to the valve cover port; and a process port piped to the process pressure to assist the spring biased piston, wherein the process port is fluidly isolated from the barrier lubricant chamber.

5. The packing system of claim 1 , wherein the bonnet port is a first bonnet port, the pressurized barrier lubricant reservoir is a first pressurized barrier lubricant reservoir, the support ring is a first support ring, and the packing inter-volume is a first packing inter-volume, the packing system further comprising: a third packing group disposed in the valve stem bore to surround a third portion of the valve stem and spaced apart from the second packing group by a second support ring to define a second packing volume within the valve stem bore, wherein the second packing group is between the first packing group and the third packing group; as well as A second pressurized barrier lubricant reservoir is in fluid communication with the second inter-packing volume via a second bonnet port in the bonnet to pressurize the barrier lubricant within the second inter-packing volume to at or above a second pressure, the second pressure being higher than the first pressure.

6. The packing system of claim 5, wherein the second pressurized barrier lubricant reservoir is arranged to sense a process pressure upstream of the first packing set relative to a leakage flow path from the flow passage through the valve stem bore to pressurize the barrier lubricant within the second pressurized barrier lubricant reservoir to above the process pressure.

7. The packing system of claim 5, further comprising: a fourth packing set disposed in the valve stem bore to surround a fourth portion of the valve stem and spaced apart from the first packing set by a third support ring to define a third packing volume within the valve stem bore, wherein the fourth packing set is between the first packing set and the valve body; and a pressure intensifier system arranged to pressurize process fluid upstream from the fourth packing set relative to a leakage flow path from the flow passage through the stem bore and provide the pressurized process fluid to the third packing volume via a third bonnet port in the bonnet.

8. The packing system of claim 1, further comprising: an additional packing set disposed in the valve stem bore to surround an additional portion of the valve stem and spaced apart from the first packing set by a third support ring to define a third packing volume within the valve stem bore, wherein the additional packing set is between the first packing set and the valve body; and a pressure intensifier system arranged to pressurize process fluid from upstream of the additional packing set relative to a leakage flow path from the flow passage through the stem bore and to provide the pressurized process fluid to the third packing volume via an additional bonnet port in the bonnet.

9. The packing system of claim 1, further comprising: a sensor arrangement configured to sense flow of barrier lubricant to the bonnet port; as well as A control system is configured to determine leakage of barrier lubricant from the inter-packing volume.

10. A valve assembly for a process flow at process pressure, the valve assembly comprising: a valve body including an inlet, an outlet, and a flow passage extending between the inlet and the outlet to direct the process flow; a valve cover mounted to the valve body and having a valve stem hole leading to the valve body; a valve stem extending through the valve stem aperture and operably connected to a control member disposed in the flow passage, the valve stem being configured to move the control member between a closed position and an open position to control flow through the flow passage; a first packing group disposed in the valve stem bore around a first portion of the valve stem; a second packing set disposed in the valve stem bore about a second portion of the valve stem, the second packing set being downstream of the first packing set relative to a leakage flow path from the flow passage through the valve stem bore to provide an inter-packing volume within the valve stem bore between the first packing set and the second packing set; and A bonnet port extends through the bonnet to provide fluid communication between the packing volume and a source of pressurized fluid at a first pressure that is higher than the process pressure.

11. The valve assembly of claim 10, wherein the source of pressurized fluid is a pressurized barrier lubricant reservoir.

12. The valve assembly of claim 11, wherein the pressurized barrier lubricant reservoir is piped to the valve stem bore upstream of the first packing set relative to the leakage flow path to pressurize the barrier lubricant in the pressurized barrier lubricant reservoir above the process pressure.

13. The valve assembly of claim 10, wherein the bonnet port is a first bonnet port, the pressurized fluid source is a first pressurized fluid source, and the packing volume is a first packing volume, the valve assembly further comprising: a third packing group disposed in the valve stem bore around a third portion of the valve stem, the third packing group being downstream of the second packing group along the leakage flow path to define a second inter-packing volume between the second packing group and the third packing group within the valve stem bore; as well as A second bonnet port extends through the bonnet to provide fluid communication between the second packing volume and a second source of pressurized fluid at a second pressure that is higher than the first pressure.

14. The valve assembly of claim 13, wherein the second source of pressurized fluid is a pressurized barrier lubricant reservoir.

15. The valve assembly of claim 14, wherein the pressurized barrier lubricant reservoir is piped to the valve stem bore upstream of the first packing set relative to the leakage flow path to pressurize the barrier lubricant in the pressurized barrier lubricant reservoir above the process pressure.

16. The valve assembly of claim 13, further comprising: a fourth packing set disposed in the valve stem bore about a fourth portion of the valve stem, the fourth packing set being upstream of the first packing set along the leakage flow path to define a third packing inter-volume within the valve stem bore, wherein the fourth packing set is between the first packing set and the valve body; and A pressure intensifier system is arranged to pressurize process fluid from upstream of the fourth packing set relative to the leakage flow path and provide the pressurized process fluid to the third packing volume via a third bonnet port in the bonnet.

17. The valve assembly of claim 16, wherein the pressure intensifier system comprises a pneumatic pump arranged to pressurize the process fluid.

18. The valve assembly of claim 10, further comprising: A sensor arrangement is configured to sense flow of fluid through the bonnet port.

19. A packing system for use with a valve assembly, the valve assembly comprising: a valve body having an inlet, an outlet, and a flow passage extending between the inlet and the outlet; and a valve cover having a valve stem hole, the valve stem hole receiving a valve stem to control flow through the flow passage, the packing system comprising: a first packing set surrounding a first portion of the valve stem in the valve stem bore and compressed to provide a first pressure drop along a leakage flow path from the flow passage through the valve stem bore; a second packing set surrounding a second portion of the valve stem in the valve stem bore, the second packing set being downstream of the first packing set relative to the leakage flow path to provide a first inter-packing volume between the first packing set and the second packing set within the valve stem bore, and being compressed to provide a second pressure drop along the leakage flow path, the second pressure drop being greater than the first pressure drop; and A barrier lubricant is pressurized to a first pressure within the first packing volume.

20. The packing system of claim 19, further comprising: a third packing set surrounding a third portion of the valve stem in the valve stem bore, the third packing set being downstream of the second packing set relative to the leakage flow path to provide a second inter-packing volume between the second and third packing sets within the valve stem bore, and being compressed to provide a third pressure drop along the leakage flow path, the third pressure drop being greater than the second pressure drop; as well as A barrier lubricant is pressurized within the second inter-packing volume to a second pressure, the second pressure being higher than the first pressure.

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