Air compressor system for remote environment

Abstract

An air compressor system is provided for generating compressed air for one or more pneumatic instruments on a pipe section. The conduit section may include a valve defining an upstream portion and a downstream portion. In one example, an expander is configured to selectively receive process fluid from an upstream portion of a conduit via an input line. In another example, a compressor is configured to receive air via an air input line and output compressed air to an air storage tank via an air output line. The expander may power the compressor via expansion of the process fluid through the expander. In one example, the expander outputs process fluid into a downstream portion of the conduit via an output line.

Description

Technical Field

[0001] The present disclosure relates to air compressor systems for use in remote environments. Background Art

[0002] Fluid control systems can be used in a variety of industrial, commercial, and other environments to regulate, protect, isolate, or maintain pipes, conduits, or other containers and the flow of fluid therein (e.g., within a pipeline). In some applications, these fluid control systems can utilize compressed air (e.g., instrument air) to control or manage fluid flow. However, typical compressors may use an electrical power source that may not be available in some remote locations. Therefore, it may be useful to generate compressed air in some locations where power is not available, which can be used to manage or control the flow of fluid in a pipeline. Summary of the invention

[0003] Some embodiments of the present invention provide an air compressor system for generating compressed air for one or more pneumatic devices on a pipeline segment. The pipeline segment may include a valve defining an upstream portion and a downstream portion. In one example, an expander is configured to selectively receive a process fluid from the upstream portion of the pipeline via an input pipeline. In another example, the compressor is configured to receive air via an air input pipeline and output the compressed air to an air storage tank via an air output pipeline. The expander can provide power to the compressor via expansion of the process fluid through the expander. In one example, the expander outputs the process fluid to the downstream portion of the pipeline via an output pipeline.

[0004] Some embodiments of the present invention provide a method for compressing air. In one example, the method includes selectively delivering a process fluid from an upstream portion of a pipeline to an expander via an input pipeline according to a path. In one example, the pipeline includes a valve located between the upstream portion and the downstream portion of the pipeline. The method also includes expanding the process fluid using an expander so that the expander rotates to provide power to a compressor. The compressor thus operates to receive air via an air input pipeline and output compressed air to an air storage tank via an air output pipeline. The method also includes delivering the expanded process fluid from the expander to a downstream portion of the pipeline via an output pipeline according to a path.

[0005] Some embodiments of the present invention provide an air compressor system for generating compressed air for one or more pneumatic instruments. The system may include a process fluid portion and an instrument air portion. The process fluid portion may include a pipeline segment, the pipeline segment including a valve defining an upstream portion and a downstream portion of the pipeline and an expander in fluid communication with the pipeline. In one example, the expander is configured to selectively receive a process fluid from an upstream portion of the pipeline via an input pipeline, and provide the expanded process fluid to a downstream portion of the pipeline via an output pipeline. The instrument air portion may include a compressor in mechanical communication with the expander to provide power to the compressor by rotation of the expander. The compressor may be configured to receive air for compression at an air inlet and supply compressed air to an air tank in fluid communication with the compressor. In one example, the air tank is configured to provide compressed air from the compressor to one or more pneumatic instruments. In one example, the compressor is powered by the flow of the process fluid from the upstream portion of the pipeline through the expander to the downstream portion of the pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0007] Figure 1 is a schematic diagram of an example of piping for an air compressor system having aspects of the present disclosure.

[0008] Figure 2 yes Figure 1 Schematic diagram of a pipeline including another configuration of an expander driven air compressor system according to aspects of the present disclosure. DETAILED DESCRIPTION

[0009] The following discussion is presented to enable those skilled in the art to make and use embodiments of the present invention. Various modifications to the illustrated embodiments will be apparent to those skilled in the art given the benefit of this disclosure, and the principles herein may be applied to other embodiments and applications without departing from embodiments of the present invention. Therefore, embodiments of the present invention are not intended to be limited to the embodiments illustrated, but should be accorded the widest scope consistent with the principles and features disclosed herein.

[0010] 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 are not necessarily drawn to scale, they 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.

[0011] 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 details of the construction and arrangement of the components 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. In addition, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered as limiting. "Including", "comprising" or "having" and its variants used herein are intended to cover the items listed thereafter and their equivalents and additional items. Unless otherwise specified or limited, the terms "installed", "connected", "supported" and "connected" and their variants are widely used and cover direct and indirect installation, connection, support and connection. In addition, "connected" and "connected" are not limited to physical or mechanical connections or connections.

[0012] As briefly discussed above, fluid control systems can be applied 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 valve actuation at remote or difficult-to-reach locations. Such remote sites may lack reliable power sources, or may occasionally suffer power outages, and would therefore benefit from a valve actuation system that does not require an external power source and does not have unnecessary fluid (e.g., natural gas) losses.

[0013] Thus, embodiments of the present invention may provide an air compressor system configured to generate compressed air without the need for an external power source. In one example, the air compressor may be powered by a process fluid flowing through a pipeline to provide compressed air for the operation of one or more devices along the pipeline. In one example, the flow of the process fluid may operate an expander configured to provide power to the compressor (e.g., via a rigid shaft or other mechanical connection between the expander and the compressor). In addition, the expander may be configured to discharge the expanded process fluid into a downstream portion of the pipeline without causing the fluid to be lost to the atmosphere. Thus, an expander-driven air compressor system may provide compressed air (e.g., instrument gas) for controlling one or more devices without the need for an external power source, and without discharging the process fluid during operation or during an idle state.

[0014] In one particular example, a series of valve arrangements can be used to control the flow of process fluid along the input line to the expander. For example, the flow to the expander can be controlled by a series of regulators or other valve arrangements and in various combinations with reference to the pressure difference across the expander, the pressure of the air tank supplied by the compressor, or the downstream pressure of the pipeline, thereby indirectly controlling the speed of the connected compressor.

[0015] Figure 1An example of an air compressor system 100 is shown. In one example, the air compressor system 100 can be an expander driven air compressor system including a process fluid portion 102 and an instrument air portion 104. In one example, the air compressor system 100 can be applied on a pipeline 106. The pipeline 106 can be a natural gas pipeline. In one example, the pipeline 106 can include a valve 118 arranged to control a fluid flow or pressure drop between an upstream portion 114 (relative to the valve 118) and a downstream portion 116 (relative to the valve 118) of the pipeline 106. The valve 118 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 for changing pipeline pressure or flow.

[0016] In some cases, an operator may wish to isolate a portion of the pipeline 106. For example, a portion of the pipeline may be isolated to enable maintenance or replacement of a section of the pipeline 106. In order to enable an operator to isolate a portion of the pipeline 106, the pipeline may include a set of isolation valves 110, 112. The isolation valves 110, 112 may be operated by a user to isolate (i.e., fluidly separate) an upstream portion 114 and a downstream portion 116 from the remaining portion 108 of the pipeline 106. In one example, the isolation valves 110, 112 are manual valves, each of which includes a manually operable valve stem configured to be actuated by a user or operator. In other examples, the isolation valves 110, 112 may be any other form of valve. In one example, closing or latching of the isolation valves 110, 112 eliminates the flow of process gas through the isolated portion (e.g., the upstream portion 114 and the downstream portion 116). As a result, the valve 118 may be rendered inoperable due to a lack of pressure drop (eg, zero pressure drop, no pressure differential to operate the actuator 120 ) between the upstream and downstream portions of the conduit 106 .

[0017] In the illustrated example, the valve 118 can be stroked (i.e., moved / actuated) via the actuator 120 to close, open, or otherwise adjust the position of the valve stem of the valve 118. Thus, by controlling the actuator 120, the valve 118 can be controlled to produce a specific pressure drop across the valve 118 or a specific flow rate of fluid into the downstream portion 116 of the pipeline 106. In one example, the actuator 120 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 122 (e.g., a spring) configured to cause the actuator to "fail open" in certain circumstances (e.g., circumstances where the pressure differential (dP) is insufficient to operate the actuator 120). In other examples, the biasing element 122 can be configured to cause the actuator to "fail closed" in certain circumstances.

[0018] In one example, the process fluid portion 102 of the system 100 includes a pipeline 106 and an expander 132 configured to generate work (e.g., via powered rotation, etc.) sufficient to power a compressor 158 located within the instrument air portion 104 of the system 100. In general, the compressor 158 can be a scroll compressor or any other form of compressor suitable for a particular installation. In one example, the expander 132 can be a large capacity expander and the compressor 158 can be a small capacity compressor that provides a total pressure ratio of 20:1 (e.g., 20 psi of compression corresponds to 1 psi of expansion).

[0019] In one particular example, the process fluid portion 102 and the instrument air portion 104 are separate systems (i.e., fluidly isolated systems in which there is no exchange of working fluid) that are connected via a shaft 160 between the expander 132 and the compressor 158. The shaft 160 can be configured to transfer work (e.g., power, rotation, etc.) from the expander 132 to operate the compressor 158.

[0020] In one example, the combination of compressor 158 and expander 132 can be configured as a compander. In other words, compressor 158 can be mechanically coupled to expander 132 so that expansion of the supply gas through expander 132 provides rotational power to compress air passing through compressor 158. In some examples, the compander can be configured as a single unit assembly having an integrated housing, support structure, or other common features.

[0021] In one example, the expander 132 may be connected to the upstream portion 114 of the pipeline 106 via an input line 124 and to the downstream portion 116 of the pipeline 106 via an output line 134. The input line 124 may route a process fluid (e.g., natural gas) from the upstream portion 114 of the pipeline 106 via an inlet port 126. Correspondingly, the output line 134 may reinject the process fluid (e.g., the process fluid expanded under reduced pressure) from the expander 132 into the downstream portion 116 of the pipeline 106 via an outlet port 136.

[0022] In some cases, the outlet port for returning the expanded process fluid to the pipeline can be a pressure reducing port, i.e., a port configured to effectively reduce the local pressure of the received expanded fluid. Similarly, the inlet port for providing the process fluid from the pipeline to the expander can be a pressure increasing port, i.e., a port configured to effectively increase the local pressure of the received process fluid. In this regard, in one example, the inlet port 126 and the outlet port 136 can be in the form of a pitot tube port to generate an increased pressure differential between the upstream and downstream portions of the pipeline relative to the process fluid passing through the expander 132. For example, as Figure 1 As shown, the inlet port 126 is a pitot tube facing in the upstream direction, so that the input line 124 is exposed to the velocity pressure of the flow along the pipe 106. In contrast, the outlet port 136 is a pitot tube facing in the downstream direction, so that the output line 134 is not exposed to the velocity pressure of the flow along the pipe 106. In other examples, other well-known devices (e.g., a venturi device at the output line 134) can be similarly adopted. In other examples, the inlet port and the outlet port can be straight pressure probes (e.g., branched or directly connected) or any other form of ports.

[0023] In one example, each of the input line 124 and the output line 134 may include an isolation valve configured to prevent the process fluid from flowing to the expander 132. For example, the input line 124 may include an isolation valve 130, and the output line 134 may include an isolation valve 138. The isolation valves 130, 138 may be actuated by a user to block the process fluid from flowing to or out of the expander 132. As should be understood, blocking or preventing the process fluid from flowing to the expander 132, thereby correspondingly preventing the compressor 158 from compressing (e.g., pressurizing) the air. Therefore, actuating the isolation valves 130, 138 effectively shuts down the compressor 158. In one example, the isolation valves 130, 138 are manual valves, each of which includes a manually operable valve stem configured to be actuated by a user. In other examples, the isolation valves 130, 138 may be any other form of valve.

[0024] In one example, the process fluid portion 102 of the air compressor system 100 may include one or more regulators or other valve arrangements configured to control the flow of process fluid into an expander 132 (e.g., an expander arranged in series along the input line 124). Because the compressor 158 and the expander 132 are connected (e.g., via the shaft 160), adjusting the flow of process fluid into the expander 132 correspondingly adjusts the compression value of the compressor 158. In other words, adjusting the amount of work done by the expander (e.g., by adjusting the amount of input process fluid) likewise adjusts the output air pressure from the compressor 158 by supplying more or less power (e.g., the speed of the shaft) to the compressor 158. Therefore, the output air pressure from the compressor 158 can be adjusted by controlling the flow of process fluid through the input line 124. In some cases, adjusting the process fluid flow into the expander 132 can be based on the pressure of the expanded process fluid output from the expander 132 to the downstream portion 116 of the pipeline 106. Thus, the regulator or other valve arrangement may also protect the expander 132 from operating at too high a speed, which may damage the expander 132 , the compressor 158 , and may protect the downstream portion 116 of the pipeline 106 from exceeding a maximum allowable operating pressure (MAOP) of the downstream portion 116 .

[0025] In one example, a speed control regulator 140 is disposed on the input line 124 to prevent the expander 132 from running at too high a speed. The speed control regulator 140 may include a biasing element 146 (e.g., a spring or other biasing element) configured to bias the regulator open to allow the process fluid to flow into the expander 132 under certain conditions. In order to regulate the flow of the process fluid entering the expander 132, the speed control regulator 140 includes an input reference line 142 and an output reference line 144. In the example shown, the reference lines 142, 144 are configured to monitor the pressure in the input line 124 and the output line 134, respectively. In another example, these or other reference lines may monitor the pressure difference across the expander 132 in other ways.

[0026] In one example, when the pressure differential between the output line 134 and the input line 124 exceeds a predetermined threshold, the regulator 140 begins to close (e.g., overcoming the biasing force from the biasing element 146), which thereby reduces the flow of process fluid into the expander 132. Thus, the expander 132 can be protected from excessive speeds, which may be caused by high flow rates or high pressures in the input line 124 and a corresponding high pressure drop across the expander 132. Conversely, if the pressure differential decreases, the regulator 140 can begin to open (e.g., with the help of the biasing element 146) to allow more process fluid to flow into the expander 132. In addition, at relatively low pressure differentials, the regulator 140 can remain fully open (e.g., by the biasing element 146). Among other benefits, this arrangement of the regulator 140 can provide a useful supply of process fluid for air compression while also helping to avoid excessive compressor speeds when the valve 118 causes a high pressure drop between the upstream portion 114 and the downstream portion 116.

[0027] In another example, the MAOP regulator 148 can be positioned on the input line 124 (e.g., positioned upstream of the rate control regulator 140) to help protect the pipeline 106 (particularly the downstream portion 116) from over-pressurization. In some examples, the MAOP regulator 148 can include a biasing element 152 (e.g., a spring or other biasing element) configured to enable the process fluid to flow into the expander 132 under certain conditions. For example, the biasing element 152 can be configured to bias the MAOP regulator 148 to be fully open unless the pressure in the output line 134 (as determined by the reference line 150) is above a predetermined threshold. Thus, if the output line 134 is above a predetermined pressure threshold (i.e., if P2 or the expanded process fluid being reinjected into the downstream portion 116 of the pipeline 106 is above a predetermined pressure), the regulator 148 begins to close (e.g., against the biasing force of the biasing element 152). In this manner, regulator 148 may prevent P2 from exceeding the set pressure via leakage of process fluid through expander 132 , for example, when valve 118 is closed.

[0028] To further control the pressurization of air by the compressor 158 (e.g., to control the pressure at the output of the compressor 158, which feeds the air storage tank 170), an air pressure regulator 172 may be positioned on the input line 124 (e.g., positioned upstream of the MAOP regulator 148 and the speed control regulator 140). The air pressure regulator 172 is configured to monitor the pressure of air in the air storage tank 170 via a reference line 174. If the pressure in the air storage tank 170 is above a predetermined threshold, the regulator 172 is configured to close (e.g., against a biasing element 176), which limits the flow of process gas into the expander 132 via the input line 124. As previously described, limiting the flow of process gas into the expander 132 correspondingly reduces the power output from the expander 132 via the shaft 160 to the compressor 158, which reduces the pressure of the compressed air from the compressor 158. Conversely, if the pressure in the air storage tank 170 decreases, the regulator 172 can be configured to open to correspondingly increase the flow to the expander 132. In one example, for example, a biasing element 176 (e.g., a spring or other biasing element) can be configured to bias the air pressure regulator 172 to be fully open unless the pressure in the air storage tank 170 is above a predetermined threshold (e.g., high enough to overcome the biasing force from the biasing element 176 and close the regulator 172). Thus, the pressure in the air storage tank 170 can be regulated by controlling the flow of the process fluid into the expander 132.

[0029] In an exemplary use case, air (e.g., from the atmosphere surrounding the system 100) enters the air inlet 154 of the instrument air portion 104 due to the suction pressure from the compressor 158. The tank air flows through an air filter 156, which is configured to remove particles or debris in the air that may damage the compressor 158. The air then flows into the compressor 158, which compresses the air to a pressure value sufficient to operate one or more instruments (e.g., pneumatic instruments along the pipeline 106). In particular, as previously described, the compressor 158 can be powered by the expansion of the process gas from the pipeline 106 through the expander 132. Therefore, the output pressure value of the compressed air from the compressor can be controlled by controlling the flow of the process gas from the upstream portion 114 of the pipeline 106 into the expander 132, and the expanded process fluid can be re-injected into the downstream portion 116 of the pipeline 106 to avoid the loss of the process fluid (e.g., natural gas) to the atmosphere.

[0030] Continuing with the above exemplary use case, the compressed air output from the compressor 158 can flow downstream through the compressed air line 162 and through the air dryer 164 including the drain 166. The dryer 164 is configured to manage the dew point (e.g., moisture content) of the compressed air and drain the moisture from the air via the drain 166. In one example, the drain 166 can be a fully pneumatic automatic drain. The dried compressed air can then flow from the dryer 164 through the check valve 168, which prevents the compressed air from flowing back from the air tank 170. As previously described, the compressed air can flow into the air tank 170, which is configured to hold the compressed air for use by one or more instruments (e.g., pneumatic instruments along or away from the pipeline 106). In some examples, the compressed air can be used to operate one or more pipeline valves (e.g., via any of various known pneumatic control assemblies (not shown) to operate the valve 118). In one example, the air tank 170 may include a pressure relief valve 178 configured to vent or release the compressed air to the atmosphere in the event that the air tank 170 is over-pressurized. The air tank 170 may also include a compressed air outlet 180 that allows compressed air to flow from the tank 170 to one or more instruments (e.g., a remotely located pneumatic instrument that is used to control a pipeline valve or other equipment).

[0031] It should be appreciated that the system 100 can therefore operate in a zero-emission state, meaning that the system 100 operates without loss of process fluid (e.g., natural gas) to the atmosphere during operation or when in an idle state. It should be appreciated that this configuration can help prevent loss of important materials (e.g., loss of process fluid) and avoid release conditions that may cause reporting requirements or other regulatory consequences (e.g., related to venting natural gas to the atmosphere). In addition, the system 100 is able to operate independently of an external power source (e.g., electricity), which allows the system 100 to operate in a remote location while not requiring electrical equipment to compress air for pneumatic control or otherwise operate one or more instruments.

[0032] Figure 2 Another example of an expander driven air compressor system 200 for use with pipeline 106 is shown (e.g., as an alternative configuration of air compressor system 100). As will be appreciated, system 200 shares many components with the previously shown and described examples and operates in a similar manner to the previously shown and described examples. For the sake of brevity, these common features will not be described in detail below. Instead, unless otherwise noted, the previous discussion of commonly named or numbered features also applies to the example configuration of system 200.

[0033] In lieu of the regulator 148 (or otherwise), the system 200 may include a slam-shut valve 202 configured to protect the pipeline 106 from over-pressurization. For example, the slam-shut valve 202 includes a reference line 204 that monitors the pressure in the downstream portion 116 of the pipeline 106. In one example, the slam-shut valve 202 is configured to close quickly and completely in response to the pressure in the downstream portion 116 of the pipeline 106 reaching or exceeding a predetermined maximum operating pressure of the pipeline 106. Thus, for example, if the pressure in the downstream portion 116 of the pipeline 106 is below a predetermined threshold, the valve 202 may be in a fully open position, and if the pressure in the downstream portion 116 of the pipeline 106 is above the predetermined threshold, the valve 202 may be in a fully closed position.

[0034] Instead of Figure 1 In the arrangement shown (or other ways), the valve 206 can be configured to control the operation of the compressor based on the pressure of the compressed air (e.g., the compressed air stored in the air tank 170) from the output end of the compressor 158. In some examples, the valve 206 is a three-way valve (or a three-way switching valve) that can be positioned between the air tank 170 and the regulator 172 to control the opening or closing of the regulator 172. In one example, the valve 206 can include one or more adjustable set points, such as an adjustable lower end set point and an adjustable upper end set point based on the air pressure in the tank 170. Correspondingly, the valve 206 can open or close one or more ports in response to a predetermined air pressure value in the tank 170. In one example, the air pressure in the tank 170 is monitored via the reference line 174, which can continuously apply the air pressure from the tank 170 to the reference port 208 of the valve 206. The reference port 208 is configured to adjust the valve 206 (e.g., open or close one or more ports) based on the reference pressure. For example, if the air pressure within the tank 170 reaches a predetermined upper limit, the port 214 (e.g., C port) of the valve 206 is closed and the port 210 (e.g., B port) of the valve 206 is opened. In one example, the B port 210 can be connected to the reference line 174 so that the compressed air from the tank 170 can flow through the B port 210 and exit from the A port 212. Therefore, the compressed air can flow into the regulator 172 and close the regulator (against the biasing force of the biasing element 176), which reduces the process fluid flow to the expander 132, and thus reduces the compressed air pressure at the outlet of the compressor 158 by reducing the power output to the compressor 158.

[0035] In another example, if the air pressure reaches a predetermined lower limit, the C port 214 of the valve 206 is opened and the B port 210 of the valve 206 is closed. Therefore, the compressed air in the regulator 172 (e.g., from the tank 170 via the A port 212) that has applied pressure to close the regulator 172 can flow out of the regulator 172 and into the A port 212. Since the B port 210 is now closed, the compressed air from the regulator 172 flows out of the C port 214, which is open to the atmosphere. Therefore, the biasing element 176 can move the regulator 172 toward the fully open position. In other words, when the pressure in the tank 170 is low enough, the valve 206 can discharge compressed air from the regulator 172 to allow the regulator 172 to open. As a result, the flow rate of the process fluid flowing to the expander 132 increases, which increases the compressed air pressure at the outlet of the compressor 158 by increasing the power output to the compressor 158.

[0036] In some embodiments, 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 of using such a device for the intended purpose, methods of otherwise achieving such functionality, 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 such purposes or functionality. Similarly, unless otherwise specified or limited, discussion herein of any method of manufacturing or using a particular device or system (including installing the device or system) is intended to inherently include disclosure of the utilized features and implemented functionality of such a device or system as an embodiment of the present invention.

[0037] In addition, as used herein, unless otherwise limited or defined, "or" indicates a non-exclusive list of components or operations that can exist in any number of combinations, rather than an exclusive list of components that can only exist as alternatives to each other. For example, a list of "A, B, or C" represents the following options: A; B; C; A and B; A and C; B and C; and A, B, and C. Correspondingly, the term "or" as used herein is intended to represent exclusive alternatives only when it is preceded by an exclusive term, such as "any one," "one of," "only one of," or "exactly one of." For example, a list of "one of A, B, or C" represents the following options: A, but not B and C; B, but not A and C; and C, but not A and B. A list preceded by "one or more" (and variant expressions thereof) and including "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" represent 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 preceded by "plurality" (and variations thereof) and including "or" to separate the listed elements represents 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" represent the following options: A and B; B and C; A and C; and A, B, and C.

[0038] 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 do not necessarily require similar orientation or geometry in all installations or configurations.

[0039] Also as used herein, unless otherwise limited or defined, "substantially parallel" means a direction whose angle with a reference direction is within ±12 degrees (e.g., within ±6 degrees) (including end values). For a nonlinear path, if a straight line between the endpoints of the path is substantially parallel to the reference direction, or the average derivative of the path in a common reference frame as the reference direction is substantially parallel to the reference direction, then the path can be considered to be substantially parallel to the reference direction.

[0040] Also as used herein, unless otherwise limited or defined, "substantially perpendicular" means a direction within a range of ±12 degrees (e.g., within a range of ±6 degrees) (including end values) perpendicular to a reference direction. For a nonlinear path, a path may be considered substantially perpendicular to a reference direction if a straight line between the endpoints of the path is substantially perpendicular to the reference direction, or if the average derivative of the path within a common reference frame as the reference direction is substantially perpendicular to the reference direction.

[0041] Also as used herein, unless otherwise limited or defined, "unitary" and its derivatives (e.g., "integrally") describe an element that is manufactured as a single piece without the need for fasteners, adhesives, etc. to secure separate components together. For example, an element that is stamped, cast, or otherwise molded from a single sheet of metal as a single piece or using a single mold, without the need for rivets, screws, or adhesives to secure the separately formed components together, is a unitary (or integrally formed) element. In contrast, an element that is formed from multiple parts that are initially formed separately and subsequently joined together is not a unitary (or integrally formed) element.

[0042] In addition, unless otherwise specified or limited, the terms "about" and "approximately" used herein for reference values ​​refer to changes of ±15% or less relative to the reference value, including the end values ​​of the range. Similarly, the term "substantially equal to" (similar expressions) used herein for reference values ​​refers to a deviation of less than ±30% (including the end values) relative to the reference value. In specified cases, "substantially" can specifically indicate a change in a numerical direction relative to the reference value. For example, "significantly less than" a reference value (similar expressions) means a value reduced by 30% or more compared to the reference value, and "significantly greater than" a reference value (similar expressions) means an increase of 30% or more compared to the reference value.

[0043] Additionally, 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, wherein the variations between the components or systems are within the limits of the acceptable tolerances for the relevant processes and specifications. For example, if two components are manufactured according to the same standardized manufacturing steps, using the same materials, and within the same acceptable dimensional tolerances (e.g., specified for a particular process or product), then the two components may be considered substantially the same.

[0044] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be apparent to those skilled in the art in view of the benefit of this disclosure, and the principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be consistent with the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An air compressor system, the air compressor system comprising: a pipeline segment including a valve defining an upstream portion and a downstream portion of the pipeline; an expander configured to selectively receive a process fluid from the upstream portion of the pipeline via an input line; and a compressor configured to receive air via an air input line and output compressed air to an air storage tank via an air output line; Wherein the expander powers the compressor via expansion of the process fluid through the expander, and the expander outputs the process fluid into the downstream portion of the pipeline via an output line.

2. The air compressor system according to claim 1, wherein: The process fluid is natural gas.

3. The air compressor system according to claim 1, further comprising: A pressure differential regulator is configured to control the flow of the process fluid entering the expander to control the rotation speed of the expander.

4. The air compressor system according to claim 3, wherein: The differential pressure regulator controls the rotation speed of the expander by comparing the pressure in the input line with the pressure in the output line.

5. The air compressor system according to claim 4, wherein: The air pressure at the air output line is related to the rotational speed of the expander, so that the pressure difference regulator controls the air pressure at the air output line by comparing the pressure in the input line with the pressure in the output line.

6. The air compressor system according to claim 1, further comprising: An overpressure regulator is configured to control the flow of process fluid into the expander based on the pressure in the downstream portion of the pipeline to prevent flow through the expander when the valve is closed.

7. The air compressor system of claim 1, wherein: The air tank supplies compressed air to one or more remotely located devices.

8. The air compressor system according to claim 1, further comprising: an air pressure regulator in fluid communication with the air tank; The air pressure regulator is configured to control a flow of the process fluid through the input line to the expander based on the pressure in the air storage tank.

9. The air compressor system according to claim 1, further comprising: a fail open valve arranged to control flow through said input line; and a three-way valve in fluid communication with the gas storage tank and the fail-open valve; wherein when the pressure in the gas tank reaches a predetermined gas tank upper limit, the three-way valve operates to close the fail-open valve; and When the pressure in the gas tank reaches a predetermined gas tank lower limit, the three-way valve operates to allow the fail-open valve to open.

10. The air compressor system according to claim 9, further comprising: A quick-closing valve assembly is configured to prevent flow through the input line in response to pressure in the downstream portion of the pipeline exceeding a predetermined pipeline upper limit.

11. The air compressor system of claim 1, wherein: The input pipeline includes one or more of the following: an input port, the output port comprising a first pitot tube opening in an upstream direction of the pipeline; or An output port includes a second pitot tube opening in a downstream direction of the pipeline.

12. A method for compressing air, the method comprising: selectively routing a process fluid from an upstream portion of a conduit to an expander via an input line, the conduit including a valve between the upstream portion and a downstream portion; expanding the process fluid with the expander so that the expander rotates to power a compressor, whereby the compressor operates to receive air via an air input line and output compressed air to an air storage tank via an air output line; and Expanded process fluid is routed from the expander via an output line into the downstream portion of the pipeline.

13. The method according to claim 12, further comprising: The speed of the expander is controlled based on the pressure at the output line.

14. The method according to claim 13, wherein: Controlling the speed of the compressor includes controlling the flow of the process fluid into the expander using a differential pressure regulator arranged to operate based on a pressure difference across the expander.

15. The method according to claim 13, further comprising: The speed of the expander is further controlled by controlling the flow along the input line using an air pressure regulator in fluid communication with the air tank.

16. The method according to claim 15, wherein: The air pressure regulator is located upstream of a differential pressure regulator configured to control the speed of the compressor by controlling the flow of the process fluid into operation based on a pressure differential across the expander.

17. The method according to claim 13, further comprising: The speed of the expander is further controlled by controlling the flow along the input line using a three-way switching valve in communication with the gas storage tank.

18. An air compressor system, comprising: A process fluid portion, the process fluid portion comprising: a pipeline segment including a valve defining an upstream portion and a downstream portion of the pipeline; and an expander in fluid communication with the pipeline, the expander configured to selectively receive a process fluid from the upstream portion of the pipeline via an input line and provide an expanded process fluid to the downstream portion of the pipeline via an output line; and An instrument air section, the instrument air section comprising: a compressor in mechanical communication with the expander so as to be powered by rotation of the expander, the compressor being configured to receive air at an inlet for compression; and an air tank in fluid communication with an outlet of the compressor, the air tank being configured to supply compressed air from the compressor to one or more pneumatic devices; The flow of process fluid from the upstream portion of the pipeline via the expander to the downstream portion of the pipeline powers the compressor to supply the compressed air to the air storage tank.

19. The air compressor system of claim 18, wherein: The speed of the compressor is controlled by a plurality of regulators connected in series along the input line.

20. The air compressor system of claim 18, further comprising one or more of the following: a pressurization inlet port configured to provide process fluid from the upstream portion of the conduit to the input line; or A reduced pressure outlet port is configured to provide expanded process fluid from the output line to the downstream portion of the pipeline.

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