Control system for emission reduction

Abstract

The invention relates to a control system for emission reduction. A fluid control system for controlling flow of process fluid through a conduit is provided. In one example, the conduit may include a valve defining an upstream portion and a downstream portion of the conduit. The system may include one or more instruments configured to control operation of the valve. In one example, a system may include a compressor and an expander configured to selectively receive a supply gas from an upstream portion of a conduit via a supply line. In one example, the supply gas flows to the compressor and the expansion machine via the supply line when the pressure difference between the upstream portion and the downstream portion of the conduit is below a predetermined threshold, and does not flow to the compressor and the expansion machine when the pressure difference between the upstream portion and the downstream portion of the conduit is above the predetermined threshold.

Description

Technical Field

[0001] The present application relates to control systems for reducing emissions. Background Art

[0002] Fluid control systems can be used in a variety of industrial, commercial, and other settings to regulate, protect, isolate, or maintain the flow of fluids in pipes, conduits, or other containers and therein (e.g., within a pipeline). In some applications, it may be useful to manage or control the flow of fluids in a pipeline when certain power sources are unavailable. However, typical control systems often vent a portion of the process fluid (e.g., pipeline gas), which can result in the loss of valuable materials (e.g., natural gas) and may trigger regulatory consequences. Summary of the invention

[0003] Some embodiments of the present invention provide a fluid control system for controlling the flow of a process fluid through a pipeline. In one example, the pipeline may include a valve that defines an upstream portion and a downstream portion of the pipeline. The system may include one or more instruments that are configured to control the operation of the valve. In one example, the system may include a compressor and an expander that are configured to selectively receive supply gas from the upstream portion of the pipeline via a supply line. In one example, when the pressure difference between the upstream portion and the downstream portion of the pipeline is lower than a predetermined threshold, the supply gas flows to the compressor and the expander via the supply line, and when the pressure difference between the upstream portion and the downstream portion of the pipeline is higher than a predetermined threshold, the supply gas does not flow to the compressor and the expander.

[0004] Some embodiments of the present invention provide a fluid control system for controlling the flow of a process fluid through a pipeline. The fluid control system may include: a valve, the valve defining an upstream portion and a downstream portion of the pipeline; and a supply line, the supply line connected to the upstream portion of the pipeline. In one example, the supply line is configured to provide a supply gas to one or more devices, and the one or more devices are configured to control the valve. In another example, the supply line is configured to provide the supply gas to a compression expander when the pressure difference between the upstream portion and the downstream portion of the pipeline is lower than a predetermined threshold. In one example, the compression expander is arranged to provide pressurized supply gas to the one or more devices. In one example, the supply line is configured to provide the supply gas directly to the one or more devices via a bypass line when the pressure difference is higher than the predetermined threshold.

[0005] Some embodiments of the present invention provide a method for controlling flow through a pipeline via a valve, the valve defining an upstream portion and a downstream portion of the pipeline. In one example, the method may include selectively directing supply gas from the upstream portion of the pipeline to a compressor and an expander configured to power the compressor via a supply line. In one example, the compressor may be operated to provide pressurized supply gas to control the operation of the valve. In one example, when the pressure difference between the upstream portion of the pipeline and the downstream portion of the pipeline is below a predetermined threshold, the supply gas may be directed to the compressor and the expander via the supply line. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0007] Figure 1 is a schematic diagram of a pipeline including an example control system according to aspects of the present invention.

[0008] Figure 2 is another configuration that includes an example control system Figure 1 Schematic diagram of the pipeline.

[0009] Figure 3 is another configuration that includes an example control system Figure 1 Schematic diagram of the pipeline. DETAILED DESCRIPTION

[0010] The following discussion is presented to enable those skilled in the art to make and use embodiments of the present invention. In view of the benefit of this disclosure, those skilled in the art will readily appreciate various modifications to the illustrated embodiments, and the principles herein may be applied to other embodiments and applications without departing from the embodiments of the present invention. Therefore, embodiments of the present invention are not intended to be limited to the illustrated embodiments, but are to be accorded the broadest scope consistent with the principles and features disclosed herein.

[0011] The following detailed description will be read with reference to the accompanying drawings, wherein the same elements in different drawings have the same reference numerals. The accompanying drawings, which are not necessarily drawn to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. The skilled person will recognize that the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention.

[0012] Before explaining any embodiment of the present invention in detail, it should be understood that the application of the present invention is not limited to the construction details and component arrangements set forth in the following description or shown in the following drawings. The present invention can have other embodiments and can be practiced or executed in various ways. And, it should be understood that the words and terms used herein are for illustrative purposes and should not be considered restrictive. 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. Unless otherwise specified or limited, the terms "install", "connect", "support" and "couple" and their variants are widely used and cover direct and indirect installation, connection, support and connection. In addition, "connect" and "couple" are not limited to physical or mechanical connections or connections.

[0013] As briefly discussed above, fluid control systems can be used in a variety of industrial, commercial, and other environments to control the flow of fluids through pipes, conduits, or other containers. For example, some process systems (including offshore drilling, oil fields, natural gas transmission pipelines, etc.) may (occasionally) require the actuation of valves in remote or difficult-to-access locations. Such remote locations may lack a reliable power source, or may otherwise experience power loss events from time to time, and would therefore benefit from a valve actuation system that has no external power source and no unnecessary loss of fluid (e.g., natural gas).

[0014] Embodiments of the present invention may provide a fluid control system configured to enable one or more instruments to operate with a supply gas (or other similar process fluid) from a pipeline, wherein in some cases, the supply gas has zero discharge to the atmosphere. In particular, some examples may be configured to power a pneumatic instrument with a supply gas for operating a pipeline valve (or other device), including when the associated pipeline provides a relatively small differential pressure (dP). Thus, for example, a process fluid may be used to control a pipeline valve in an unpowered position, and the fluid control system may discharge the process fluid (e.g., instrument gas) back to the pipeline without losing the fluid to the atmosphere.

[0015] Typically, a compressor and an expander can be provided, wherein a process fluid is delivered to each to provide an independent powered system. In one example, a fluid control system includes a compression expander, the compression expander including a compressor and an expander configured to provide power to the compressor. In one example, power is provided to the compression expander via a process fluid from a pipeline. The compressor can be configured to pressurize the supply gas to increase the pressure of the process fluid, which enables the device to operate even when the pressure difference between the upstream and downstream portions of the pipeline is minimal. In one example, power is provided to the expander by extracting the process fluid from the upstream portion of the pipeline from the pipeline via a supply line, and the expander is mechanically coupled to the compressor to provide power to the compressor. Therefore, the compressor can compress the supply gas to provide at least a predetermined pressure difference value, which is sufficient to operate the pneumatic device and re-inject the used gas from the device into the pipeline.

[0016] Figure 1 An example of a fluid control system 100 is shown. In one example, the fluid control system 100 can be used on a pipeline 102. The pipeline 102 can be a natural gas pipeline or otherwise arranged to carry a process fluid. In one example, the pipeline 102 can include a valve 108 arranged to control a fluid flow rate or pressure drop between an upstream portion 104 (relative to the valve 108) and a downstream portion 106 (relative to the valve 108) of the pipeline 102. The valve 108 can be any of a variety of known types, such as a ball valve, a gate valve, a butterfly valve, a diaphragm valve, a stop valve, a plug valve, a check valve, or any other form of valve used to modify pipeline pressure or flow.

[0017] In the example shown, the valve 108 can be stroked (i.e., moved / actuated) via the actuator 110 to close, open, or otherwise adjust the position of the valve stem 112 of the valve 108. Thus, through control of the actuator 110, the valve 108 can be controlled to produce a specific pressure drop across the valve 108 or to produce a specific flow rate of fluid into the downstream portion 106 of the pipeline 102. In one example, the actuator 110 can be a double-acting piston-type actuator. In another example, the actuator can be a single-acting piston-type actuator, or can have other known configurations. In some examples, the actuator can include a biasing element 114 (e.g., a spring) configured to cause the actuator to "fail closed" (e.g., when the pressure is insufficient to operate the actuator 110). In other examples, the biasing element 114 can be configured to cause the actuator to "fail open" under certain circumstances.

[0018] In one example, the fluid control system 100 includes a fluid powered instrument assembly 124 (e.g., a pneumatic (i.e., gas-operated) instrument of various known configurations) arranged to control the operation of a valve via control of an actuator 110. In one example, one or more pneumatic instruments may be operated via the use of an instrument gas (e.g., a supply gas regulated to a predetermined pressure differential value) that may be delivered from an upstream portion 104 of the conduit via a supply line 132 and reinjected into a downstream portion 106 of the conduit 102 after use (as further described below). As previously mentioned, the instrument assembly 124 may require a predetermined pressure differential in order to operate the instrument to adjust the actuator 110. In some cases, including when the valve 108 is fully open, the pressure differential between the upstream portion 104 and the downstream portion 106 may be insufficient to operate the instrument assembly 124 (and the actuator 110). Therefore, in order to increase the pressure of the instrument gas, a compressor 150 is disposed within the control system 100.

[0019] Compressor 150 can be configured to pressurize supply gas selectively received from supply line 132 to a predetermined value to provide a sufficient pressure differential to operate actuator 110. In addition, as also generally described above, compressor 150 can supply instrument gas at a sufficient pressure so that the gas can flow back into conduit 102 once exhausted by instrument assembly 124. Supply gas can be selectively provided to compressor 150, for example, by controlling one or more valves in fluid communication with compressor 150 (e.g., by operating a regulator arrangement between compressor 150 and conduit 102, including as further described below).

[0020] In one example, compressor 150 may be a pneumatically driven compressor, such as a scroll compressor. However, in some examples, various other known types of compressors may be suitable.

[0021] In one example, compressor 150 is powered by a supply gas that is delivered through expander 152 to generate work sufficient to power compressor 150. In some cases, supply gas may be selectively delivered to the expander similar to delivery to compressor 150 (see above), including delivery in parallel streams branching from a common supply line. In some cases, supply gas may be selectively delivered to compressor 150 and expander 152 simultaneously (e.g., through a common regulator arrangement, including as further described below).

[0022] In one example, the combination of compressor 150 and expander 152 can be configured as a compander, including Figure 1In other words, compressor 150 may be mechanically coupled to expander 152 such that expansion of the supply gas through expander 152 provides rotational power to compress the supply gas through compressor 150. In some examples, the compander may be configured as an integral assembly having an integrated housing, support structure, or other common features.

[0023] To prevent loss of process fluid through the expander 152, the expander can be connected to the downstream portion 106 of the pipeline 102 via a discharge port 154, which discharges the supply gas from the expander 152 to the downstream portion 106 of the pipeline 102. Therefore, the expander 152 can be sized or otherwise configured so that the supply gas discharged from the expander can be at a sufficient pressure to be reinjected into the downstream portion of the pipeline (i.e., a pressure greater than or equal to P2). In one example, the expander 152 can be a large volume expander and the compressor 150 can be a small volume compressor, which provides an overall pressure ratio of 20:1 (i.e., 20 psi compression to 1 psi expansion). In other examples, other pressure ratios can be provided.

[0024] In one example, the pressure of the process fluid from the upstream portion 104 of the pipeline 102 can be regulated to a predetermined value arranged along the supply line 132 (e.g., with a regulator). In one example, the pressure of the process fluid can be sensed to control the operation of the compressor 150 and the expander 152. For example, the differential pressure regulator 142 can be arranged to reference the pressure in the downstream portion of the pipeline (e.g., pressure (P2)) via a first reference line 146, and to reference the pressure at the compressor output via a second reference line 148. If the pressure at the compressor output is above a certain value, the regulator 142 is closed. This directs the supply gas from the pipeline 102 to flow through the bypass line 134 (overcoming the check valve 136), that is, to provide the instrument gas to the input line 130 of the instrument assembly 124 without the compressor 150 pressurizing it. In particular, the regulator 142 can be configured to ensure that the pressure provided to the input line 130 (as provided via the flow through the compressor 150) is high enough so that the instrument gas can be re-injected into the pipeline 102 after experiencing the operating pressure drop of the instrument assembly 124. In other words, for example, regulator 142 may be configured to ensure that compressor 150 operates to ensure that pressure ratio P2 exceeds at least the operating pressure drop of instrument assembly 124 (plus any required safety factors or other accommodations for anticipated pressure drops).

[0025] In one example, the input line 130 may include a regulator 158 (e.g., a high pressure regulator) configured to regulate the pressure in the input line 130 to ensure sufficient (e.g., predetermined) pressure for operating one or more instruments and reinjecting gas into the conduit 102. For example, the regulator 158 may be configured to provide a sufficiently high instrument gas flow to the pressurization chamber for operating the pneumatic control system (with an operational dP) and reinjecting spent instrument gas into the conduit 102 without further pressurization.

[0026] If the pressure at the compressor output is instead below the associated set pressure, the regulator 142 opens, which allows the supply gas to flow through the compressor input line 138 to both the compressor 150 and the expander 152 (e.g., an integrated compression expander). As previously mentioned, the expander 152 generates work via the expansion of the supply gas to power the compressor 150, which pressurizes the supply gas for operating the instrument assembly 124. Additionally, the gas moving through the expander (e.g., after expansion) is directed to the downstream portion 106 of the pipeline 102 via the exhaust port 154 to prevent the supply gas from being lost to the atmosphere. The instrument gas leaving the compressor 150 (overcoming the check valve 156) backfills the bypass line 134, which closes the check valve 136 and directs the instrument gas into the input line 130, as previously discussed. In one example, the regulator 142 may include a biasing element 144, e.g., a spring, configured to cause the regulator to "fail open." In other words, the regulator 142 may be configured to default to enabling the supply gas to flow through the compressor 150 and the expander 152 during certain fault events and during periods of low differential pressure in the pipeline 102 .

[0027] In other words, if the pressure at the output of compressor 150 is higher than the pressure in the downstream portion of the pipeline (e.g., P2) plus the desired pressure differential (as well as any safety factors, etc.), regulator 142 closes and enables supply gas to flow through bypass line 134 into instrument assembly 124. Thus, for example, via a connection along bypass line 134 via check valve 136, if P1 is sufficiently high relative to P2, instrument assembly 124 may be operated solely via supply gas flow through bypass line 134. However, if the pressure at the output of compressor 150 is lower than the associated set pressure (as discussed above), regulator 142 opens and enables supply gas to flow through compressor 150 and expander 152 to increase the pressure available to instrument assembly 124 and also prevent supply gas from flowing from supply line 132 through bypass line 134 (e.g., by closing check valve 136).

[0028] In some examples, the fluid control system 100 can operate in a zero-emission state, meaning that the system 100 does not lose gas (e.g., pipeline gas, instrument gas, supply gas) to the atmosphere when operating and idle. It should be appreciated that such a configuration can help prevent the loss of valuable materials (e.g., via gas loss) and avoid release events that may trigger reporting requirements or other regulatory consequences (e.g., associated with the venting of natural gas to the atmosphere).

[0029] In the illustrated example, to achieve this zero-discharge condition, one or more of the instruments (e.g., positioners, relays, regulators, volume boosters, trip valves, etc.) of the instrument assembly 124 used to control the operation of the valve 108 are contained within a pressurized chamber 122 (e.g., provided using a known type of pressure vessel or other pressure-containing structure). Thus, the control system 100 can be operated to float (or dynamically adjust) the internal pressure of the chamber 122 to match or exceed the pressure (P2) in the downstream portion 106 of the pipeline 102. In particular, as further discussed above, the control system 100 can be configured to operate the compressor 150 as needed to ensure appropriate input pressure to the instrument assembly 124 so that the fluid discharged by the instrument assembly 124 has a sufficiently high pressure to be re-injected into the downstream portion 106 (without further compression).

[0030] In other words, the pressurized chamber 122 of the control system 100 can be a closed system relative to the atmosphere. Thus, instead of referencing atmospheric pressure, instruments inside the chamber 122 can instead reference the pressure in the downstream portion 106 of the conduit 102. Thus, any gas exhausted or otherwise lost from the control system 100 can be reinjected into the downstream portion 106 of the conduit 102 via the exhaust port 160 (e.g., a simple pipe connection) without further pressurization (and corresponding power requirements). Similarly, the flow of gas between the chamber 122 and the downstream portion 106 of the conduit 102 via the exhaust port 160 enables the chamber 122 and the downstream portion 106 of the conduit 102 to reach equilibrium, wherein the chamber (and instrument reference) pressure changes based on the pressure in the downstream portion 106 of the conduit 102.

[0031] In one example of controlling the operation of the control system 100, the instrument assembly 124 communicates with one or more electronic devices (e.g., a controller 120). The controller 120 is configured to monitor the position of the actuator 110 and the pressure in the downstream portion 106 of the pipeline 102 to determine whether the valve 108 needs to be adjusted. In one example, the controller 120 is located outside the chamber 122 (i.e., exposed to atmospheric pressure / reference atmospheric pressure). In one example, the controller 120 is electrically connected (e.g., hardwired or wirelessly connected) to the pressure transducer 118 and the stroke transducer 116. The pressure transducer 118 is configured to monitor and report the pressure (P2) in the downstream portion 106 of the pipeline 102. The stroke transducer 116 is configured to monitor and report the position of the actuator 110 (corresponding to the position of the valve 108). In one example, the pressure transducer 118 is positioned outside the pressurized chamber 122 to provide a gauge pressure reading (relative to atmospheric pressure) of the downstream portion 106.

[0032] In one example, the instrument assembly 124 is connected to the first line 126 and the second line 128. In the example shown, the flow of instrument gas from the instrument assembly 124 into the second line 128 supplies gas to the second side 162 of the actuator 110, which restricts the flow of gas through the valve 108 (e.g., closes the valve 108). Similarly, the flow of instrument gas into the first line 126 supplies gas to the first side 164 of the actuator 110, which increases the flow of gas through the valve 108 (e.g., opens the valve 108). Throughout the valve actuation process, the controller 120 can monitor the pressure transducer 118 and the travel transducer 116. During such actuation, as also disclosed above, any working gas exhausted from the instrument is captured within the chamber 122 and exhausted into the downstream portion 106 of the pipeline via the exhaust port 160. Therefore, the control system 100 operates in a zero-emission state with no gas lost to the atmosphere.

[0033] Figure 2 Shows that it can be Figure 1 Another example of a fluid control system 200 for use with a conduit 102 of the embodiment of the present invention (e.g., as an alternative configuration of the fluid control system 100). As will be appreciated, the fluid control system 200 shares a number of common components with the previously shown and described examples and operates in a similar manner. For the sake of brevity, these common features will not be described in detail below. Instead, unless otherwise indicated, the previous discussion of commonly named or numbered features also applies to the example configuration of the control system 200.

[0034] In some cases, an operator may wish to isolate a portion of the pipeline 102. For example, a portion of the pipeline may be isolated to enable maintenance and / or replacement of a section of the pipeline 102. To enable an operator to isolate a portion of the pipeline 102, the pipeline may include a set of isolation valves 204, 210. The isolation valves 204, 210 may be operated by a user to fluidly isolate the upstream portion 104 and the downstream portion 106 from the remainder 202 of the pipeline 102. In one example, the isolation valves 204, 210 are manual valves, each of which includes a manually operable valve stem 206, 212 configured to be actuated by a user or operator. In other examples, the isolation valves 204, 210 may be any other form of valve.

[0035] As will be appreciated, closing the isolation valves 204, 210 may eliminate process gas flow through the isolated portions (e.g., the upstream portion 104 and the downstream portion 106). As a result, the valve 108 may be rendered inoperable due to the lack of a pressure drop between the upstream portion 104 and the downstream portion 106 of the pipeline 102. Additionally, the corresponding lack of flow may prevent the operation of the compressor 150 and the expander 152 (i.e., the compander) from generating a pressure differential.

[0036] To enable operation of the valve 108, the fluid control system 200 may therefore include one or more exhaust valves, such as a manual exhaust valve 214 and a solenoid-powered exhaust valve 216. In one example, the system 200 may include only the manual valve 214, only the solenoid valve 216, any other form of exhaust valve, or any combination thereof. To enable operation of the valve 108, the exhaust valve 214 or the exhaust valve 216 may be opened, which exhausts the pressurized gas within the chamber 122 and enables the instrument assembly 124 to reference atmospheric pressure rather than the downstream pipeline pressure (e.g., P2). Thus, a sufficient pressure differential may be generated relative to the upstream portion 104 to at least temporarily debug, test, or otherwise operate the valve 108. To prevent gas from flowing back from the downstream portion of the pipeline 102, a set of check valves 218, 220 are arranged on the exhaust ports 154, 160. In one example, a flow meter may be positioned downstream (or otherwise) of the exhaust valves 214, 216 to record the volume of gas exhausted during operation.

[0037] Figure 3 Shows that it can be Figure 1 Another example of a fluid control system 300 for use with a conduit 102 of the embodiment of the present invention (e.g., as an alternative configuration of the fluid control system 100). As will be appreciated, the fluid control system 300 shares a number of common components with the previously shown and described examples and operates in a similar manner. For the sake of brevity, these common features will not be described in detail below. Instead, unless otherwise indicated, the previous discussion of commonly named or numbered features also applies to the example configuration of the control system 300.

[0038] In some examples, more than one control valve or other instrument can benefit from the high pressure gas produced by the compressor 150. For example, the high pressure tank 310 can be positioned on the output line 308 of the compressor 150. In particular, the high pressure tank 310 can thus provide the high pressure gas to the input line 130 for use in operating the instrument assembly 124 and subsequently re-injecting the pipeline 102. In addition, the high pressure tank 310 can also provide the high pressure gas to one or more remote control valves, instruments, or other pneumatic devices via the output supply line 312 (e.g., for operating other remotely or alternatively located control systems, including for controlling other pipeline valves).

[0039] In some examples, similar arrangements can allow for the co-delivery of low-pressure gas, including that which can be caused by the operation of various pneumatic control systems. For example, one or more of the previously mentioned control valves, instruments, or other pneumatic devices (added to chamber 122) can discharge gas to a low-pressure tank 314 via exhaust ports 160, 318. The low-pressure tank 314 can then store low-pressure gas as needed and can also discharge the low-pressure gas to a specific outlet. In one example, the low-pressure tank 314 can discharge to the downstream portion 106 of the pipeline 102 via a pipeline discharge line 320, or to an alternative pressure sink via a discharge line 316. In one example, the low-pressure tank 314 automatically determines the lowest pressure sink via check valves 322, 324.

[0040] In some implementations, the devices or systems disclosed herein may be utilized, manufactured, or installed using methods that embody aspects of the present invention. Accordingly, any description herein of a particular feature, capability, or intended purpose of a device or system is generally intended to include disclosure of methods for using such a device for its intended purpose, methods for otherwise achieving such capabilities, methods for manufacturing related components of such a device or system (or the device or system as a whole), and methods for installing disclosed (or otherwise known) components to support such purposes or functions. Similarly, unless otherwise indicated or limited, discussion herein of any method for manufacturing or using a particular device or system (including installing the device or system) is intended to inherently include disclosure of features utilized and capabilities achieved by such a device or system as an embodiment of the present invention.

[0041] 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. Correspondingly, 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) 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.

[0042] As used herein, unless otherwise defined or limited, directional terminology is used for ease of reference for discussion of a particular figure or example. For example, references to a downward (or other) direction or a top (or other) position may be used to discuss aspects of a particular example or figure, but similar orientations or geometries are not necessarily required in all installations or configurations.

[0043] Also as used herein, unless otherwise limited or defined, "substantially parallel" refers to a direction within ±12 degrees (e.g., within ±6 degrees) of a reference direction, including that direction. For a nonlinear path, a path may be considered substantially parallel to a reference direction if a straight line between the endpoints of the path is substantially parallel to the reference direction, or if the average derivative of the path within a common reference frame serving as the reference direction is substantially parallel to the reference direction.

[0044] Also as used herein, unless otherwise limited or defined, "substantially perpendicular" refers to a direction within ±12 degrees (e.g., within ±6 degrees) of being perpendicular to a reference direction, including that direction. For a nonlinear path, a path may be considered substantially perpendicular to a reference direction if a straight line between the path endpoints is substantially perpendicular to the reference direction, or if the average derivative of the path within a common reference frame serving as the reference direction is substantially perpendicular to the reference direction.

[0045] Also as used herein, unless otherwise limited or defined, "integral" and its derivatives (e.g., "integrally") describe an element that is manufactured as a single piece, without fasteners, adhesives, etc., securing the separate components together. For example, an element that is formed from a single piece of sheet metal or stamped, cast, or otherwise molded into a single-piece component using a single die, without rivets, screws, or adhesives securing the separately formed pieces together, is an integral (and integrally formed) element. In contrast, an element that is formed from multiple pieces that are initially formed separately and then later joined together is not an integral (or integrally formed) element.

[0046] Additionally, unless otherwise specified or limited, the terms "approximately" and "approximately" used herein with respect to a reference value refer to a variation of ±15% or less from the reference value, including the endpoints of the range. Similarly, the term "substantially equal" (and similar terms) used herein with respect to a reference value refers to a variation of less than ±30% from the reference value, including the endpoints. Where specified, "substantially" may particularly refer to a variation in a numerical direction relative to the reference value. For example, "substantially less than" a reference value (and similar terms) indicates a value that is reduced by 30% or more from the reference value, and "substantially greater than" a reference value (and similar terms) indicates a value that is increased by 30% or more from the reference value.

[0047] Also as used herein, unless otherwise limited or specified, "substantially the same" refers to two or more components or systems that are manufactured or used according to the same processes and specifications, where the variations between the components or systems are within the limits of acceptable tolerances for the relevant processes and specifications. For example, if two components are manufactured according to the same standardized manufacturing steps, with the same materials, and within the same acceptable dimensional tolerances (e.g., as specified for a particular process or product), then the components may be considered substantially the same.

[0048] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. In view of the benefit of this disclosure, various modifications of these embodiments will be readily apparent to those skilled in the art, and the principles defined herein may be applied to other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fluid control system, comprising: a conduit including a valve defining an upstream portion and a downstream portion of the conduit; one or more instruments configured to control operation of the valve; a compressor configured to selectively receive a supply gas from the upstream portion of the conduit via a supply line and provide pressurized gas to the one or more instruments; as well as an expander configured to selectively receive a supply gas from the upstream portion of the pipeline via the supply line, the expander configured to provide power to the compressor; Wherein when the pressure difference between the upstream portion of the pipeline and the downstream portion of the pipeline is below a predetermined threshold, supply gas flows to the compressor and the expander via the supply line. 2 . The fluid control system of claim 1 , wherein the fluid control system blocks supply gas from flowing to the compressor and the expander when the pressure differential is above the predetermined threshold.

3. The fluid control system according to claim 2, wherein the fluid control system further comprises: A differential pressure regulator is arranged to control the flow of supply gas to the compressor and the expander.

4. The fluid control system according to claim 1, further comprising: An input line delivers a pressurized flow of instrument gas from the output of the compressor to the one or more instruments at a predetermined pressure.

5. The fluid control system according to claim 1, further comprising: a bypass line disposed between the supply line and the input line; Wherein the fluid control system provides flow of supply gas through the bypass line to the one or more instruments when a pressure differential between the upstream portion of the conduit and the downstream portion of the conduit is above a predetermined threshold.

6. The fluid control system of claim 1, wherein the one or more instruments are in fluid communication with an actuator configured to operate the valve.

7. The fluid control system of claim 1, further comprising: a pressurized chamber at a reference pressure greater than or equal to the pressure in the downstream portion of the conduit; Wherein the one or more instruments are retained within the pressurized chamber.

8. A fluid control system according to claim 7, wherein the one or more instruments are arranged to release instrument gas to be captured within the pressurized chamber and reinjected into the downstream portion of the conduit via an exhaust port.

9. The fluid control system of claim 8, wherein the exhaust port includes a drain valve, and wherein opening the drain valve changes the reference pressure of the pressurized chamber from the reference pressure to atmospheric pressure.

10. The fluid control system of claim 1, wherein high pressure supply gas from the output of the compressor flows into a high pressure tank arranged to supply the one or more instruments and one or more remote instruments.

11. The fluid control system of claim 1, wherein low pressure supply gas from the output of the expander flows into a low pressure tank, and wherein low pressure instrumentation gas from one or more remote instruments flows into the low pressure tank.

12. The fluid control system of claim 11, wherein the low pressure tank is in fluid communication with a plurality of pressure sinks and is configured to discharge to a lowest pressure sink among the plurality of pressure sinks via one or more check valves.

13. A fluid control system, comprising: a conduit including a valve defining an upstream portion and a downstream portion of the conduit; as well as a supply line connected to the upstream portion of the conduit, the supply line configured to provide a supply gas to one or more instruments configured to control the valve; wherein the supply line is configured to provide supply gas to a compandor arranged to provide pressurized supply gas to the one or more instruments when a pressure differential between the upstream and downstream portions of the conduit is below a predetermined threshold; and The supply line is configured to provide supply gas directly to the one or more instruments via a bypass line when the pressure difference is above the predetermined threshold.

14. The fluid control system of claim 13, wherein the flow of supply gas to the compander is controlled by a regulator.

15. The fluid control system of claim 13, wherein the pressurized supply gas from the output of the compander flows to the one or more instruments via an input line at a predetermined pressure.

16. A fluid control system according to claim 13, wherein the one or more instruments are maintained within a pressurized chamber, and wherein the pressurized chamber provides a reference pressure to the one or more instruments, the reference pressure being greater than or equal to the pressure in the downstream portion of the pipeline.

17. The fluid control system of claim 16, wherein instrument gases released by the one or more instruments are captured within the pressurized chamber and reinjected into the downstream portion of the conduit via an exhaust port.

18. The fluid control system of claim 13, wherein the high pressure supply gas from the output of the compander flows into a high pressure tank, and wherein the high pressure tank supplies high pressure instrumentation gas to the one or more instruments and one or more remote instruments.

19. A method of controlling flow through a conduit via a valve, the valve defining an upstream portion and a downstream portion of the conduit, the method comprising: selectively directing supply gas from the upstream portion of the conduit via a supply line to a compressor and an expander configured to power the compressor, the compressor thereby operating to provide pressurized supply gas to one or more instruments, and the one or more instruments operating with the pressurized supply gas to control operation of the valve; Wherein supply gas is directed to the compressor and the expander via the supply line when a pressure difference between the upstream portion of the pipeline and the downstream portion of the pipeline is below a predetermined threshold.

20. The method according to claim 19, further comprising: selectively directing a supply gas to the one or more appliances via a bypass line, the bypass line bypassing the compressor and the expander; Wherein when the pressure differential is below the predetermined threshold, supply gas is directed to the one or more instruments via the bypass line.

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