Patent Publication Number: US-2023134352-A1

Title: Emissions management modules and associated systems and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. provisional patent application Ser. No. 63/273,703 filed Oct. 29, 2021, and entitled “Emissions Management Modules and Associated Systems and Methods,” which is hereby incorporated herein by reference in its entirety for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     Natural gas is a naturally occurring hydrocarbon gas utilized for a variety of purposes, including as an energy source for heating, cooking, and for the generation of electricity. Natural gas may also comprise a fuel source for chemical and refining processes in the petrochemical and other industries. Natural gas systems include natural gas wells from which the natural gas is produced as well as pipeline systems through which the natural gas is transported to gathering systems, processing systems, etc., and ultimately to end users for consumption. Methane (CH 4 ), the primary component of natural gas is a greenhouse gas thought to have a potentially harmful impact on the Earth&#39;s atmosphere when released to the environment. Emissions of hydrocarbons, both accidental and by design, from the natural gas system are one of many potential sources of methane released to the environment. One potential source of leakage and/or venting of these materials from the natural gas system are natural gas compressor packages that form part of the natural gas system. Compressor packages are used, among other things, to transport natural gas to and through natural gas pipelines. Typical compressor packages of natural gas systems include a “driver” (typically a reciprocating internal combustion engine powered by natural gas) that drives a reciprocating natural gas compressor. 
     SUMMARY 
     An embodiment of a natural gas system comprises a process suction conduit, a compressor package connected downstream of the process suction conduit and configured to receive a flow of natural gas from the process suction conduit and to increase a pressure of the flow of natural gas whereby the flow of natural gas is discharged from the compressor package as a pressurized flow of natural gas, a process discharge conduit connected downstream of the compressor package and configured to receive the flow of natural gas discharged from the compressor package, and an emissions management module coupled to the compressor package and configured to capture emissions from the compressor package, wherein the emissions management module comprises a vapor recovery unit (VRU) configured to circulate the captured emissions from the VRU along an emissions discharge conduit coupled to the VRU to at least one of the process suction conduit, a fuel gas system of the natural gas system, and a hydrocarbon processing component of the natural gas system that is separate from the compressor package. In some embodiments, the VRU comprises a compressor and a motor configured to drive the compressor. In some embodiments, the emissions management module comprises a support structure, and a power source supported on the support structure and configured to power the motor of the VRU. In certain embodiments, the motor of the VRU is configured to receive electrical energy from an electrical power grid. In certain embodiments, the compressor package comprises a cooling system comprising a fan and a driveshaft configured to rotate the fan, and an electrical generator coupled to the driveshaft, wherein the generator is configured to convert rotation of the driveshaft into electrical energy, and to supply the electrical energy to the emissions management module. In some embodiments, the VRU comprises a gas ejector powered by a motive fluid flow. In some embodiments, the motive fluid flow comprises a flow of natural gas from the process discharge conduit. In certain embodiments, the natural gas system comprises a blowdown emissions conduit extending from a blowdown system of the compressor package to the VRU of the emissions management module, wherein a first valve is positioned along the blowdown emissions conduit configured to selectively isolate the VRU from the blowdown system, and a bypass conduit extending from the blowdown emissions conduit to the emissions discharge conduit, and wherein a second valve is positioned along the bypass conduit to selectively isolate the connection formed between the blowdown emissions conduit and the discharge emissions conduit formed by the bypass conduit. In certain embodiments, the natural gas system comprises an emissions inlet conduit extending from the compressor package to the VRU of the emissions management module, wherein the VRU is configured to receive emissions from at least one of a seal of a seal system of the compressor package and a vent of a vent system of the compressor package. In some embodiments, the VRU is configured to maintain the emissions inlet conduit under a vacuum. In some embodiments, the emissions management module comprises a support structure on which the VRU is supported, and wherein the support structure comprises a road transportable skid. In certain embodiments, the natural gas system comprises a plurality of the compressor packages arranged in parallel with respect to each other, and a plurality of the emissions management modules, wherein each of the emissions management modules is associated with one of the plurality of the compressor packages. In certain embodiments, the VRU comprises a high-pressure circuit comprising a high-pressure gas circulator configured to receive a first stream of emissions from the compressor package, and a low-pressure circuit separate from the high-pressure circuit and comprising a low-pressure gas circulator configured to receive a separate second stream of emissions from the compressor package. In some embodiments, at least one of the high-pressure gas circulator and the low-pressure gas circulator comprises a compressor. In some embodiments, at least one of the high-pressure gas circulator and the low-pressure gas circulator comprises a gas ejector. In certain embodiments, one of the high-pressure gas circulator and the low-pressure gas circulator discharges into a fuel gas conditioner of the compressor package. In certain embodiments, the compressor package comprises a first compressor package of a plurality of compressor packages of the natural gas system, and wherein the emissions management module is connected to the plurality of compressor packages in parallel whereby the emissions management module is configured to capture emissions from each of the plurality of compressor packages. In some embodiments, the VRU of the emissions management module is configured to circulate the captured emissions to a fuel header connected to, and upstream from, a fuel gas conditioner of the compressor package. 
     An embodiment of an emissions management module for a natural gas system comprises a support structure, a first emissions inlet conduit supported on the support structure and configured to receive a first stream of emissions from the natural gas system, a second emissions inlet conduit supported on the support structure and configured to receive a second stream of emissions separate from the first stream of emissions, a vapor recovery unit (VRU) supported on the support structure connected to both the first emissions inlet conduit and the second emissions inlet conduit, wherein the VRU comprises a gas circulator in fluid communication with the first emissions inlet conduit and the second emissions inlet conduit, and a discharge conduit connected to the VRU and configured to circulate the first stream of emissions and the second stream of emissions from the VRU to a component of the natural gas system. In some embodiments, the support structure comprises a road transportable skid. In some embodiments, the gas circulator of the VRU comprises a compressor and an electric motor configured to drive the compressor. In certain embodiments, the emissions management module comprises a power source supported on the support structure and configured to power the motor of the VRU. In certain embodiments, the motor of the VRU is configured to receive electrical energy from an electrical power grid. In some embodiments, the VRU comprises the gas ejector powered by a flow of natural gas from the process discharge conduit. In some embodiments, the VRU comprises a high-pressure circuit comprising a high-pressure gas circulator configured to receive a first stream of emissions from the natural gas system, and a low-pressure circuit separate from the high-pressure circuit and comprising a low-pressure gas circulator configured to receive a separate second stream of emissions from the natural gas system. In certain embodiments, at least one of the high-pressure gas circulator and the low-pressure gas circulator comprises a compressor. In certain embodiments, at least one of the high-pressure gas circulator and the low-pressure gas circulator comprises a gas ejector. In some embodiments, the emissions discharge conduit is connected between the VRU and a fuel gas conditioner of the natural gas system defining a flowpath for at least one of the first stream of emissions and the second stream of emissions extending from the VRU to the fuel gas conditioner. In some embodiments, the component comprises a hydrocarbon processing component of the natural gas system which receives an input process stream of the natural gas system and discharges a discharged process stream of the natural gas system. In certain embodiments, the emissions discharge conduit comprises at least one of a first emissions discharge conduit connected to the VRU and configured to circulate at least one of the first stream of emissions and the second stream of emissions from the VRU to a fuel gas conditioner of the compressor package, and a second emissions discharge conduit connected to the VRU and configured to circulate at least one of the first stream of emissions and the second stream of emissions from the VRU to a hydrocarbon processing component of the natural gas system that is separate from the compressor package. In certain embodiments, the emissions management module comprises a control panel configured to control the operation of the VRU of the emissions management module and a power source for powering the control panel, wherein the power source comprises one or more batteries charged by a solar panel. 
     An embodiment of a method for capturing emissions from a compressor package of a natural gas system comprises (a) transporting a flow of natural gas from a process suction conduit of the natural gas system to a compressor package of the natural gas system, (b) increasing a pressure of the flow of natural gas received from the process suction conduit by the compressor package, (c) discharging the flow of natural gas from the compressor package to a process discharge conduit of the natural gas system, (d) capturing emissions from the compressor package by an emissions management module of the natural gas system, and (e) circulating the captured emissions by a vapor recovery unit (VRU) of the emissions management module to at least one of the process suction conduit, a fuel gas system of the natural gas system, and a hydrocarbon processing component of the natural gas system that is separate from the compressor package. In some embodiments, the method comprises (f) generating electrical energy by an electrical generator coupled to a driveshaft of a cooling system of the compressor package, the electrical generator configured to generate the electrical energy in response to rotation of the driveshaft, and (g) supplying the electrical energy to the emissions management module. In some embodiments, (e) comprises transporting the captured emissions by a gas ejector of the VRU, wherein the gas ejector is powered by a motive fluid flow. In certain embodiments, the motive fluid flow comprises a flow of natural gas discharged by the compressor package. In certain embodiments, (d) comprises (d1) receiving blowdown emissions by the emissions management module from a blowdown system of the compressor package, and (d2) bypassing the blowdown emissions by a bypass conduit around the VRU to return the blowdown emissions to the process suction conduit whereby a pressure of the blowdown system is decreased. In some embodiments, (d) comprises receiving blowdown emissions by the emissions management module from a blowdown system of the compressor package whereby are circulated through the VRU before circulating to the process suction conduit. In some embodiments, (d) comprises separately capturing emissions from a plurality of the compressor packages of the natural gas system by the emissions management module. In certain embodiments, (d) comprises capturing a first stream of emissions from the compressor package by a high-pressure circuit of the VRU and separately capturing a second stream of emissions from the compressor package by a low-pressure circuit of the VRU that is separate from the high-pressure circuit. In certain embodiments, (e) comprises circulating the captured emissions by the VRU to at least one of a fuel header connected to, and upstream from, a fuel gas conditioner of the compressor package, and a hydrocarbon processing component of the natural gas system that is separate from the compressor package. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings in which: 
         FIG.  1    is a schematic view of an embodiment of a natural gas system; 
         FIG.  2    is a schematic view of another embodiment of a natural gas system; 
         FIG.  3    is a schematic view of another embodiment of a natural gas system; 
         FIG.  4    is a schematic view of another embodiment of a natural gas system; 
         FIG.  5    is a schematic view of embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  6    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  7    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  8    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  9    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  10    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  11    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; 
         FIG.  12    is a schematic view of other embodiments of a compressor package and an emissions management module of the natural gas system of  FIG.  1   ; and 
         FIG.  13    is a flowchart of an embodiment of a method for capturing emissions from a compressor package of a natural gas system. 
     
    
    
     DETAILED DESCRIPTION 
     The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment. 
     Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness. 
     In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a particular axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to a particular axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. As used herein, the terms “approximately,” “about,” “substantially,” and the like mean within 10% (i.e., plus or minus 10%) of the recited value. Thus, for example, a recited angle of “about 80 degrees” refers to an angle ranging from 72 degrees to 88 degrees. 
     As described above, one potential source for the leakage and/or venting of emissions, including greenhouse gasses such as natural gas and/or its combustion byproducts, to the environment are compressor packages of natural gas systems. As used herein, the term “emissions” is defined as referring to the emission or release of a hydrocarbon (e.g., methane and other materials) bearing material from a component of a natural gas system, including a compressor package of a natural gas system. Emissions may contain both hydrocarbons and other materials such as carbon dioxide. Additionally, emissions may either be accidental in the form of leaks or inadvertent releases of hydrocarbon bearing materials from a component of the natural gas system, as well as releases of hydrocarbon bearing materials by design from a component of the natural gas system, such as what typically occurs during the “blowdown” of a compressor package of conventional natural gas systems. 
     Typically, natural gas (again, predominantly comprising methane) and/or other greenhouse gasses may leak or be vented from various sources of the compressor package. Typically, a majority of the greenhouse gasses produced by a compressor package is the carbon dioxide produced from the exhaust of the natural gas engine of the compressor package as a result of the combustion process. However, in addition to the carbon dioxide vented by the exhaust of the natural gas engine as a result of the combustion process, compressor packages may also release emissions in other ways. For example, some compressor packages include controls (e.g., control louvers, liquid level controllers, etc.) which use natural gas as their motive power. These natural gas controls of the compressor package may vent natural gas during operation (either continuously or intermittently). Additionally, compressor packages may (accidentally or by design) vent emissions in the form of natural gas escaping from the packing cases of the piston rods of the compressor of the compressor package. As a further example, when the compressor package is shutdown due to, for example, the performance of maintenance, the natural gas present within the compressor package is conventionally vented via a blowdown system of the compressor package to either a flare or the atmosphere. 
     Various systems have been developed to capture one or more of these sources of greenhouse gasses emitted by compressor packages so as to minimize the amount of emissions produced by the compressor package during operation. For example, systems have been developed to capture emissions in the form of natural gas vented from the compressor package (e.g., from the blowdown system of the compressor package) and to route the captured natural gas to a vapor recovery unit of the natural gas system comprising the compressor package. The captured emissions may then be stored and/or flared whereby the natural gas is combusted prior to being released to the environment. However, these recovery systems require the building of additional stationary infrastructure in the form of tank batteries, compressors, and/or flares tailored to the specific natural gas system, increasing the overall cost associated with building and operating the natural gas system. Additionally, the flaring of captured emissions typically undesirably produces at least some greenhouse gasses which are vented to the atmosphere. 
     Alternatively, some conventional recovery systems route emissions captured from the compressor package directly to a fuel or air intake of the natural gas engine of the compressor package. For example, some conventional recovery systems may take advantage of the vacuum produced by the suction-side of the natural gas engine (e.g., the suction produced by a turbocharger of the natural gas engine) and thus route the captured emissions directly to the natural gas engine. Thus, some conventional recovery systems route captured emissions directly to the natural gas engine such that the natural gas engine itself may provide the motive force for conveying the emissions to the natural gas engine. The term “directly” refers in this context to the routing of the captured emissions to the natural gas engine at a location downstream from equipment of the natural gas engine for conditioning (e.g., filtering equipment, pressure control equipment) the fuel gas supplied to the natural gas engine prior to being consumed by the engine. However, it may be undesirable for a variety of reasons to route captured emissions directly to the natural gas engine of the compressor package as a fuel source for the natural gas engine. For example, the captured emissions may damage or otherwise reduce the reliability of the natural gas engine without being properly conditioned prior to being consumed by the natural gas engine. The captured emissions may also interfere with the operation of the control system used to operate the natural gas engine when the captured emissions are received by the natural gas engine downstream from equipment used to monitor the flow of fuel gas to the natural gas engine. In addition, it is not possible to utilize captured emissions as a fuel source in applications where an electric motor, rather than a natural gas engine, is utilized as the driver of the compressor package. Further, emissions captured from a blowdown system of the compressor package typically cannot be immediately utilized as a fuel source by the engine given that the engine of the compressor package is typically shut-off during the blowdown process. 
     Accordingly, embodiments described herein include natural gas systems comprising one or more emissions management modules configured to capture emissions from one or more compressor packages, and to circulate those captured emissions to one or more component of the natural gas system. Embodiments of emissions management modules disclosed herein may be self-contained and modularized and thus easily integrated into pre-existing natural gas systems with minimal additional work required. Particularly, the emissions management module may be connected to one or more separate compressor packages of the natural gas system whereby the emissions management module may capture emissions from a variety of different emissions sources of the one or more compressor packages. Embodiments of emissions management modules disclosed herein may advantageously connect to multiple compressor packages of a pre-existing natural gas system to capture and process emissions from the plurality of compressor packages simultaneously in parallel. The incorporation of self-contained emissions management modules into pre-existing natural gas systems may eliminate the need for additional, potentially emissions-producing infrastructure to the natural gas system, such as tank batteries and/or flares for processing the captured emissions. Moreover, the emissions captured by the subject emissions management modules do not interfere with the operation of the engine. 
     As will additionally be discussed herein, embodiments of emissions management modules disclosed herein may capture emissions from various sources of a compressor package. For instance, emissions management modules described herein may capture instrumentation and/or control emissions (e.g., liquid level controllers, louvers controllers, control valves), piston rod packing system emissions, and/or blowdown system emissions. Additionally, embodiments of emissions management modules disclosed herein may include a vapor recovery unit (VRU) used to circulate the captured emissions from the emissions management module to a component of the natural gas system. In some embodiments, the VRU may comprise one or more compressors. However, in other embodiments, the VRU may comprise one or more ejectors or other gas circulators driven by the flow of motive natural gas processed by the compressor package, thereby eliminating the need for a mechanically driven compressor. 
     As will further be discussed herein, embodiments of emissions management modules may return the captured emissions to the compressor package (or other component of the natural gas system) at a variety of locations. For example, embodiments of emissions management modules disclosed herein may return captured emissions to a suction of one or more compressor packages whereby the captured emissions may be compressed by the compressor of the one or more of the compressor packages. Additionally, embodiments of emissions management modules disclosed herein may return captured emissions to the compressor package or other hydrocarbon processing component of the natural gas system as fuel gas to be consumed by the compressor package (e.g., consumed by a driver of the compressor package) or other hydrocarbon processing component (e.g., consumed by a burner assembly of the component). As used herein, the term “hydrocarbon processing component” is defined as referring to any component of a natural gas system which receives a process stream of hydrocarbons (e.g., oil, natural gas) and may include various types of equipment including boilers, furnaces, heat exchangers, separators, compressors (including compressor packages), and other equipment. As understood in the oil and gas industry, processing equipment, as that term is characterized here, may also be referred to as production equipment and, as such, references to the former are intended to be inclusive of the latter. As will be discussed further herein, emissions management modules disclosed herein, when utilizing captured emissions as a fuel source for a natural gas engine of the compressor package, return the captured emissions to the compressor package at a location upstream from fuel gas conditioning equipment of the natural gas engine so that the returned captured emissions do not damage or otherwise hinder the operation of the natural gas engine. 
     Referring now to  FIG.  1   , an embodiment of a natural gas system  10  is shown. In this exemplary embodiment, natural gas system  10  comprises a pipeline system for transporting natural gas from a production or other natural gas system to end-users and/or consumers of the natural gas transported by natural gas system  10 . However, natural gas system  10  may also comprise other types of natural gas systems including, for example, a production system in which natural gas is produced from a wellbore extending through a subterranean earthen formation. 
     In this exemplary embodiment, natural gas system  10  generally includes a process first or upstream pipeline  12 , a process second or downstream pipeline  14 , a process inlet or suction header  16 , a process second or discharge header  18 , a plurality of compressor packages  30  each comprising a compressor  32 , and a plurality of emissions management modules  40 . Natural gas system  10  is represented schematically in  FIG.  1    and may include features or components not illustrated in  FIG.  1   . Upstream pipeline  12  receives a flow of process gas (in the form of natural gas in this exemplary embodiment) from equipment connected thereto such as another pipeline, a wellhead, a compressor package, etc., and discharges the flow of natural gas to the suction header  16 . 
     In this exemplary embodiment, the compressor  32  of each compressor package  30  receives a portion of the flow of natural gas supplied by upstream pipeline  12  via a process suction conduit  22  which extends from the suction header  16  to the compressor package  30 , and discharges a flow of natural gas to the discharge header  18  via a process discharge conduit  24  extending from the compressor package  30  to the discharge header  18 . Suction header  16  is connected to each of the suction conduits  22  while discharge header  18  is connected to each of the discharge conduits  24 . The compressor packages  30  of natural gas system  10  compress the flow of natural gas received by upstream pipeline  12  (via the intervening suction header  16  and suction conduit  22 ) and discharges the flow of natural gas to downstream pipeline  14  connected thereto (via the intervening discharge conduit  24  and discharge header  18 ) which transports the flow of natural gas to equipment connected thereto such as, for example, another pipeline, another compressor package, etc., until the natural gas ultimately reaches the end-users and/or consumers of the natural gas. 
     Compressor packages  30  of natural gas system  10  may be disposed in parallel and thus may each receive a portion of the flow of natural gas received by upstream pipeline  12 . Although natural gas system  10  is shown as including three compressor packages  30  in  FIG.  1   , the number of compressor packages  30  of natural gas system  10  may vary. Each compressor package  30  of natural gas system  10  generally includes a compressor  32  and a driver  34  which is mechanically connected with and drives the compressor  32 . As used herein, the term “driver” is defined as a component configured to produce mechanical energy for mechanically driving a compressor. For example, the driver may produce mechanical energy in the form of rotational torque for rotating a crankshaft of a reciprocating compressor. Drivers may be powered by a variety of distinct energy sources. As one example, a driver may comprise a natural gas engine which combusts natural gas to produce rotational torque. As another example, a driver may comprise an electric motor which produces rotational torque from electrical energy supplied to the electric motor. 
     In this exemplary embodiment, compressor  32  comprises a reciprocating compressor including a reciprocating piston rod assembly  33 ; however, in other embodiments the configuration of compressor  32  may vary. Additionally, in this exemplary embodiment, driver  34  comprises an engine powered by natural gas and thus may also be referred to herein as natural gas engine  34 . For example, driver  34  may be powered by the flow of natural gas received by the compressor package  30  from the upstream pipeline  12 ; however, in other embodiments, the configuration of driver  34  may vary. In some embodiments, driver  34  comprises a reciprocating internal combustion engine. In other embodiments, driver  34  may not comprise an engine and instead may comprise, for example, an electric motor and/or other component (a hydraulic drive, etc.) for producing mechanical energy to mechanically drive the compressor  32 . Thus, driver  34  may also be referred to herein as electric motor  34 . 
     Emissions management modules  40  of natural gas system  10  capture emissions produced from the compressor packages  30  to thereby reduce the amount of emissions, including greenhouse gasses (primarily methane), communicated, directly or indirectly, to the atmosphere by compressor packages  30  during the operation of natural gas system  10 . The emissions captured by emissions management modules  40  may comprise, for example, natural gas vented from controls of compressor packages  30  accidentally (e.g., via damage or failure) or by design (e.g., natural gas-actuated pneumatic controllers), emissions from the packing of piston rod assembly  33  (e.g., via damage or failure), emissions from a blowdown system of compressor packages  30  (accidentally or intentionally), and/or other sources of emissions of compressor packages  30 . In this exemplary embodiment, emissions management modules  40  recycle the captured emissions and return them to the process stream (i.e., the natural gas stream that is being processed/compressed by the compressor packages  30 ) upstream from the compressor packages  30  from which the emissions are captured such as, for example, to the suction header  16  and/or one or more of the suction conduits  22 . In this manner, the emissions captured by emissions management modules  40  may be recycled back into the flow of natural gas and ultimately discharged to the discharge pipeline  14  once compressed by compressor packages  30 . It may be understood that in other embodiments the captured emissions may be consumed as fuel gas by one or more components of the natural gas system  10 . 
     In this exemplary embodiment, each emissions management module  40  is connected to a corresponding compressor package  30 . Particularly, each emissions management module  40  is connected to a corresponding compressor package  30  by one or more emissions inlet conduits  42  extending from the compressor package  30  to the emissions management module  40 . Additionally, an emissions discharge conduit  44  extends from the emissions management module  40  to the suction conduit  22  extending to the compressor package  30  associated with the given emissions management module  40 . In this configuration, the emissions management module  40  captures emissions (primarily methane) from the corresponding compressor package  30  via emissions inlet conduit  42 , and returns or recycles the emissions to the suction conduit  22  via emissions discharge conduit  44 . In this configuration, a continuous loop is formed which includes suction conduit  22 , compressor package  30 , emissions inlet conduit  42 , emissions management module  40 , and emissions discharge conduit  44 . In other embodiments, emissions discharge conduit  44  may extend to the suction header  16  rather than the suction conduit  22  and/or to some other natural gas conduit located upstream from the compressor package  30 . 
     Additionally, each emissions management module  40  includes equipment to process or condition the emissions captured from the corresponding compressor package  30  prior to returning the captured emissions to the suction conduit  22  positioned upstream from the compressor package  30 . In this exemplary embodiment, each emissions management module  40  comprises a VRU  41  including a gas circulator for driving the circulation of the emissions captured from the corresponding compressor package  30  such that the emissions may be circulated to the suction conduit  22 . As used herein, the term “gas circulator” is defined as referring to any device configured for driving or powering the circulation of gas from a first location to a second location. The gas circulators described herein may have one or more moving (e.g., rotating) parts driven by a power source. Alternatively, gas circulators disclosed herein may not include any moving parts and instead may be driven by a motive fluid. For example, the gas circulator of VRU  41  may comprise a compressor, an ejector or eductor, and/or other devices known in the art for circulating a gas stream. The VRU  41  may be powered by a power supply of the emissions management module  40  (e.g., a generator, a solar panel or array) or via an external source of power such as power supplied by the associated compressor package  30 , another external source of power such as an electric grid, or motive natural gas downstream of natural gas system  10 . 
     Emissions management modules  40  provide a means for capturing emissions produced by compressor packages  30  while minimizing the additional infrastructure which must be added to natural gas system  10 . For example, an additional tank battery or flare need not be connected to emissions management modules  40  given that emissions management modules  40  conveniently recycle the captured emissions to the suction conduits  22  of natural gas system  10  where the emissions may be processed and discharged by compressor packages  30  to the downstream pipeline  14 , thereby preserving the captured emissions for downstream processing and sale rather than having the captured emissions potentially communicated to the atmosphere. Indeed, emissions management modules  40  may conveniently be added to a pre-existing natural gas system with minimal modification to the natural gas system needed to interface the emissions management modules  40  with the natural gas system. Additionally, emissions management modules  40  do not feed the captured emissions directly to the driver  34  (downstream from any fuel gas conditioning equipment of the driver  34  such as a fuel filter or pressure regulator of driver  34 ) of the associated compressor package  30 , avoiding the undesirable effects (e.g., decline in reliability and/or performance of driver  34 ) associated with routing emissions directly to the driver  34  as a fuel source for the driver  34 . 
     Referring briefly to  FIG.  2   , another embodiment of a natural gas system  50  is shown. Natural gas system  50  includes features in common with natural gas system  10  shown in  FIG.  1   , and shared features are labeled similarly. Particularly, in this exemplary embodiment, natural gas system  50  includes an emissions management module  40  which captures emissions from a plurality of separate compressor packages  30 . Additionally, in this exemplary embodiment, emissions discharge conduit  44  extends from emissions management module  40  to the suction header  16 . Thus, emissions captured by emissions management module  40  are recirculated to each of the compressor packages  30  of natural gas system  50 . While in this exemplary embodiment emissions management module  40  captures emissions from a pair of compressor packages  30 , in other embodiments a single emissions management module  40  may capture emissions from more than two separate compressor packages  30 . The ratio of compressor packages  30  to emissions management modules  40  may vary depending the requirements of the particular application. 
     Referring to  FIG.  3   , another embodiment of a natural gas system  70  is shown. Natural gas system  70  includes features in common with natural gas system  10  shown in  FIG.  1    and natural gas system  50  shown in  FIG.  2   , and shared features are labeled similarly. In this exemplary embodiment, natural gas system  70  includes a pair of compressor packages  80  and an emissions management module  72  which captures emissions from the pair of compressor packages  80 . 
     Particularly, each compressor package comprises a fuel gas conditioner  82  configured to filter or condition fuel gas supplied to the driver  34  of the compressor package  80  (the driver  34  being in fluid communication with the fuel gas conditioner  82 ) by a fuel source  90  of the natural gas system  70 . Fuel gas conditioner  82  comprises equipment for conditioning the fuel gas before it is consumed by the driver  34 . In some embodiments, fuel gas conditioner  82  comprises a fuel filter, a liquid separator, and/or one or more pressure regulators. In this exemplary embodiment, natural gas system  70  additionally includes a fuel header or manifold  92  positioned between the fuel source  90  and the pair of compressor packages  80 , the fuel header  92  serving to distribute fuel gas from the fuel source  90  to the pair of compressor packages  80 . Particularly, in this exemplary embodiment, a pair of fuel gas conduits  93  extend from the fuel header  92  to the fuel filters  82  of the pair of compressor packages  80 , thereby connecting the fuel header  92  with the compressor packages  80 . In this configuration, the fuel filters  82  of compressor packages  80  are located downstream from the fuel header  92 , which is similarly located downstream from the fuel source  90 . In some embodiments, fuel source  90  may comprise natural gas diverted from the upstream pipeline  12  and/or suction conduits  22  of the natural gas system  70 . Thus, the fuel source  90  may comprise a suction-side component (e.g., upstream pipeline  12  and/or suction conduits  22 ) of natural gas system  70 . In other embodiments, fuel may be sourced from a compressor discharge, interstage compression, or a non-compression gas source of the natural gas system  70 . 
     In this exemplary embodiment, emissions management module  72  receives emissions captured from compressor packages  80  via emissions inlet conduits  42 , and return the captured emissions to a fuel system  91  of the natural gas system  70  including the fuel source  90 , fuel header  92 , and fuel gas conduits  93 . Particularly, emissions management module  72  returns at least a portion of the captured emissions to the fuel header  92 , upstream from the fuel filters  82  of the compressor packages  80 . The captured emissions, after being filtered or otherwise conditioned by fuel filters  82  may be consumed by drivers  34  of compressor packages  80  to assist in powering the drivers  34 . In some instances, providing the captured emissions to the drivers  34  as fuel may maximize the efficiency of the natural gas system  70  by reducing the amount of captured emissions which are directed to compressor packages  80  to be compressed by the compressors  32  of packages  80 . 
     As will be discussed further herein, the VRU  41  of emissions management module  72  may apply a motive force or pressure (positive or negative pressure) to the captured emissions permitting the captured emissions to be communicated from the module  72  to the fuel header  92  thereof without reliance on drivers  34  themselves to provide said motive force. This permits the captured emissions to be routed upstream of the fuel filters  82  of compressor packages  80  such that the captured emissions may be properly filtered or otherwise conditioned before being supplied to drivers  34 . In this manner, the captured emissions directed to the fuel system  91  by emissions management module  72  appears as just another fuel source (in addition to fuel source  90 ) to the fuel header  92 , limiting or preventing any undesirable impacts to the operation of drivers  34  through the inclusion of the captured emissions in the fuel sources thereof, while also minimizing the amount of work required to incorporate the emissions management module  70  into a preexisting natural gas system (e.g., the natural gas system  70  shown in  FIG.  3   ). Particularly, an emissions discharge conduit  74  of the emissions management module  72  may merely be connected between the emissions management module  72  and the fuel header  92 . The connection formed between emissions discharge conduit  74  and fuel header  92  may be like any other connection formed between fuel header  92  and other components of fuel system  91 , such as the connection formed between fuel source  90  and fuel header  92 . 
     While in this exemplary embodiment the fuel system  91  of natural gas system  70  includes fuel source  90 , fuel header  92 , and fuel gas conduits  93 , it may be understood that in other embodiments fuel system  91  may not include fuel header  92  with emissions discharge conduit  74  being connected to fuel system  91  at another location also located upstream from the fuel filters  82  (e.g., connected to the fuel gas conduits  93 ) of compressor packages  80  similarly permitting the captured emissions to be filtered or otherwise conditioned by fuel filters  82  before being supplied to drivers  34 . It may similarly be understood that fuel system  91  may include additional components not shown in  FIG.  3   . 
     Referring to  FIG.  4   , another embodiment of a natural gas system  95  is shown. Natural gas system  95  includes features in common with natural gas system  10 ,  50  and  70  shown in  FIGS.  1 ,  2  and  3   , respectively, and shared features are labeled similarly. Natural gas system  95  includes the pair of compressor packages  80  and the emissions management module  72  described above. Additionally, in this exemplary embodiment, natural gas system  95  includes a hydrocarbon processing component  97  coupled to the emissions management module  72 . 
     The hydrocarbon processing component  97  of natural gas system  95  may comprise various types of equipment used in the processing and production of process gas (e.g., natural gas) accomplished by the natural gas system  95 . Hydrocarbon processing component  97  may not otherwise be directly connected or otherwise directly associated with either of the compressor packages  80  and instead may relate to an unrelated subsystem of the natural gas system  95 . As an example, hydrocarbon processing component  97  may comprise a pressure vessel such as a boiler, a furnace, a compressor package, a heat exchanger, etc. Indeed, compressor packages  80  comprise hydrocarbon processing components and may also be referred to herein as such. 
     Hydrocarbon processing component  97  receives an inlet process gas stream  13  of the natural gas system  95 , processes the natural gas received from the inlet process stream  13 , and discharges a discharge process gas stream  15  which is supplied or distributed to other equipment of natural gas system  95 . The natural gas comprising the inlet process gas stream  13  and/or the natural gas comprising discharge process gas stream  15  may be similar in composition to the natural gas flowing through upstream pipeline  12 . Additionally, the hydrocarbon processing component  97  receives fuel gas from a fuel gas conduit  96  extending to the hydrocarbon processing component  97  from the fuel source  90  of fuel gas system  91 . The fuel gas supplied to the hydrocarbon processing component  97  via fuel gas conduit  96  is consumed by the component  97  as part of processing the inlet process gas stream  13  received by the hydrocarbon processing component  97 . For example, the fuel gas supplied to hydrocarbon processing component  97  may be burned in a burner assembly of the hydrocarbon processing component  97  to heat the inlet process gas stream  13  to assist in separating as desired one fraction of the inlet process gas stream  13  from another fraction of the inlet process gas stream  13 . 
     In this exemplary embodiment, in addition to being configured to discharge emissions captured from compressor packages  80  to the fuel header  92  via the emissions discharge conduit  74 , emissions management module  72  is also configured to discharge captured emissions to the hydrocarbon processing component  97  via a branch emissions discharge conduit  98 , and to the suction header  16  via a supplemental emissions discharge conduit  99 . Particularly, in this exemplary embodiment, branch emissions discharge conduit  98  extends from the emissions discharge conduit  74  to the fuel gas conduit  96  extending to the hydrocarbon processing component  97 . Alternatively, branch emissions discharge conduit  98  may extend directly between emissions management module  72  and the fuel gas conduit  96 . Additionally, in this exemplary embodiment, the supplemental emissions discharge conduit  99  extends from the emissions management module  72  to the suction header  16 . Alternatively, supplemental emissions discharge conduit  99  may extend from the emissions discharge conduit  74  to the suction header  16 . 
     In this exemplary embodiment, captured emissions may be circulated from the VRU  41  of emissions management module  72  to the fuel filters  82  of compressor packages  80 , the hydrocarbon processing component  97 , and/or to the suction header  16 . In this exemplary embodiment, valves  77 ,  78 , and  79  are positioned along each of conduits  74 ,  98 , and  99 , respectively, whereby conduits  74 ,  98 , and  99  may be selectably isolated as desired by an operator of natural gas system  95 . 
     As an example, a valve  79  positioned along the supplemental emissions discharge conduit  99  may be closed whereby emissions captured from compressor packages  80  are directed from the emissions management module  72  to the fuel header  92  and hydrocarbon processing component  97  (as fuel gas delivered to component  97  via the fuel gas conduit  96 ) but not to the suction header  16 . Alternatively, a valve  78  positioned along branch emissions discharge conduit  98  may be closed whereby captured emissions are directed from the emissions management module  72  to the fuel header  92  and suction header  16  but not to the hydrocarbon processing component  97 . As an additional alternative, a valve  77  positioned along emissions discharge conduit  74  may be closed whereby captured emissions are directed from the emissions management module  72  to the hydrocarbon processing component  97  and suction header  16  but not to the fuel header  92 . As an additional alternative, multiple valves  77 ,  78 , and  79  may be closed at a given time such that captured emissions are directed from the emissions management module  72  to only one of the suction header  16 , fuel header  92 , and hydrocarbon processing component  97 . As a further alternative, each of the valves  77 ,  78 , and  79  may be open whereby captured emissions are directed from the emissions management module  72  concurrently to the suction header  16 , fuel header  92 , and hydrocarbon processing component  97 . The selection of which valves  77 ,  78 , and  79  to close and which of valves  77 ,  78 , and  79  to remain open may be based on the current needs of the natural gas system  95 , such as, among other reasons, the current volume of captured emissions being discharged from the emissions management module  72 . 
     Referring now to  FIG.  5   , an embodiment of a compressor package  100  and an emissions management module  150  of a natural gas system are shown in greater detail. The compressor package  100  shown in  FIG.  5    may comprise one or more of the compressor packages  30  while the emissions management module  150  shown in  FIG.  5    may comprise one or more of the emissions management modules  40  of the natural gas system  10  (or other natural gas systems) shown in  FIG.  1   . In this exemplary embodiment, compressor package  100  generally includes a driver  102  and a reciprocating compressor  104  driven by the driver  102 . In this exemplary embodiment, driver  102  comprises a natural gas engine; however, in other embodiments, the configuration of driver  102  may vary. For example, in other embodiments, driver  102  may comprise an electric motor. Additionally, compressor package  100  includes a cooling system  110  for cooling components of the compressor package  100  including driver  102  and/or compressor  104 . In this exemplary embodiment, cooling system  110  includes, among other features, a cooling fan  112  driven by a driveshaft  114 . Driveshaft  114  of cooling system  110  may be driven by the driver  102  of compressor package  100 . 
     In this exemplary embodiment, emissions management module  150  generally includes a support structure  152 , an onboard power source  154 , a VRU  156 , an air system  180 , and a control panel or system (illustrated schematically by box  190  in FIG.  5 ) for controlling the operation of at least some components of emissions management module  150 . In this exemplary embodiment, support structure  152  may comprise a skid upon which the components of emissions management module  150  (e.g., onboard power source  154 , VRU  156 , air system  180 , etc.) are positioned. However, in other embodiments, the configuration of support structure  152  may vary. For instance, in some embodiments, support structure  152  may comprise a road-transportable trailer. The onboard power source  154  provides power to components of emissions management module  150  including, for example, VRU  156 . In this exemplary embodiment, onboard power source  154  comprises an electrical generator powered by the flow of natural gas provided by suction header  16  of natural gas system  10 . However, in other embodiments, the configuration of onboard power source  154  may vary. Additionally, in this exemplary embodiment, onboard power source  154  provides 460 volt (V) three-phase electrical power to the components of emissions management module  150 ; however, it may be understood that the type and magnitude of power outputted by onboard power source  154  may vary depending on the given application. 
     The VRU  156  of emissions management module  150  processes emissions captured by emissions management module  150  from compressor package  100  prior to returning the captured emissions to natural gas system  10  at a location upstream from compressor package  100 . VRU  156  of emissions management module  150  generally includes a motor  158  and a gas circulator  160  driven by the motor  158 . In this exemplary embodiment, gas circulator  160  comprises a compressor and thus may also be referred to herein as compressor  160 . Additionally, in this exemplary embodiment, motor  158  comprises an electric motor powered by the onboard power source  154  of emissions management module  150 ; however, in other embodiments, the configuration of motor  158  may vary. For example, in other embodiments, motor  158  may comprise a natural gas motor powered by the flow of natural gas provided by suction header  16 . Compressor  160  is mechanically driven by motor  158  and may comprise a rotary compressor which may include a screw, scroll, rotary vane or other types of rotors. In other embodiments, compressor  160  may comprise a reciprocating compressor. As will be discussed further herein, compressor  160  compresses emissions received by the VRU  156  prior to returning the emissions to the suction of compressor package  100 . Particularly, in this exemplary embodiment, VRU  156 , and particularly compressor  160 , receive emissions via an emissions suction conduit  162  and discharge pressurized emissions via an emissions discharge conduit  164  of emissions management module  150 . 
     The air system  180  of emissions management module  150  provides compressed or pressurized air to power features of compressor package  100  via one or more conduits (not shown in  FIG.  5   ) extending between emissions management module  150  and compressor package  100 . The compressed air provided by air system  180  may replace the natural gas used to power at least some of the pneumatically powered instrumentation and/or controls (illustrated schematically by box  120  in  FIG.  5   ) of compressor package  100  such as, for example, louvers of cooling system  110 , liquid level controllers, pre-lube motors, the starter motor, etc., of compressor package  100 . The amount of greenhouse gasses produced by compressor package  100  during operation may be reduced by substituting natural gas with air for powering at least some of the instrumentation and/or controls  120  of compressor package  100  via the air system  180  of emissions management module  150 . Additionally, by housing air system  180  on the emissions management module  150 , the amount of additional infrastructure to be provided by compressor package  100  (e.g., an air compressor, etc.) may be minimized. 
     In this exemplary embodiment, air system  180  generally includes an air receiver  182  and an air compressor  184 . Air compressor  184  may be powered by onboard power source  154  of emissions management module  150 ; however, the configuration and manner of powering air compressor  184  may vary in other embodiments. In still other embodiments, emissions management module  150  may not include air system  180 . In some embodiments, air system  180  may also include an air dryer to reduce moisture in the air after it is compressed by air compressor  184 . 
     Emissions management module  150  may capture emissions from compressor package  100  from various sources of compressor package  100 . For example, in this exemplary embodiment, a first emissions inlet conduit  166  and a second emissions inlet conduit  168  each extend from compressor package  100  to the suction conduit  162  of emissions management module  150 . In other embodiments, the number of emissions conduits extending from compressor package  100  to the suction conduit  162  of emissions management module  150  may vary from that shown in  FIG.  5   . In this exemplary embodiment, first emissions inlet conduit  166  may receive emissions vented from a variety of sources from compressor package  100 . For example, the emissions received by first emissions inlet conduit  166  may include vented natural gas from a seal system (indicated schematically by box  122  in  FIG.  5   ), and/or vent system (indicated schematically by box  123  in  FIG.  5   ) of the compressor package  100 . The seal system  122  of compressor package  100  comprises various seals of the compressor package  100  used to seal various corresponding interfaces of the compressor package  100  and which may inadvertently emit emissions over time as the performance of the given seal degrades. For example, seal system  122  may include piston rod packing seals which seal the piston rod assembly  33  of compressor package  100 , variable volume pocket seals, and others. The vent system  123  of compressor package  100  comprises various vents of the compressor package  100  used to vent, by design, various emissions for various purposes. For example, the vent system  123  may include vented emissions originating from instrumentations and/or controls  120  of compressor package  100 . Vent system  123  may also include emissions vented by so called “breathers” of the compressor package  100  such as, for example, a compressor frame breather, an engine crankcase breather of the compressor package  100 . 
     The emissions received by first emissions inlet conduit  166  may include sources of emissions produced by compressor package  100  other than those originating from seal system  122  and vent system  123 . For example, the emissions received by first emissions inlet conduit  166  may also include exhaust gas from a starter motor used to start the driver  102  of compressor package  100 , and a pre-lube motor associated with a lubrication system of compressor package  100 . 
     Second emissions inlet conduit  168  is configured to receive emissions from a blowdown system (indicated by box  124  in  FIG.  4   ) used to vent natural gas from compressor package  100  when package  100  is shut down for maintenance or other purposes. In some applications, the blowdown emissions vented to second emissions inlet conduit  168  may be at a relatively high pressure which cannot be directly fed to the VRU  156  of emissions management module  150 . Thus, in this exemplary embodiment, emissions management module  150  includes a blowdown bypass conduit  170  extending from the second emissions inlet conduit  168  to the discharge conduit  164 . Additionally, a first or low pressure (LP) blowdown valve  172  is positioned along second emissions inlet conduit  168  between the suction conduit  162  and the location at which blowdown bypass conduit  170  connects with second emissions inlet conduit  168 . Further, a second or high pressure (HP) blowdown valve  174  is positioned along blowdown bypass conduit  170 . In some embodiments, the operation of blowdown valves  172 ,  174  may be controlled by control panel  190  powered by a power source  191 . Power source  191  may be located on and/or off support structure  152  and may comprise batteries, a solar panel or array to charge one or more batteries, and/or other power sources. 
     Upon shutting down compressor package  100 , LP blowdown valve  172  may be in a closed position while HP blowdown valve  174  is an open position, permitting pressurized blowdown emissions within second emissions inlet conduit  168  to bypass VRU  156  and flow into the suction conduit  22  via discharge conduit  164 . The additional volume provided by suction header  16  and suction conduit  22  allows for the pressure within blowdown system  124  and second emissions inlet conduit  168  to bleed down to a desired reduced pressure equal to the fluid pressure within suction header  16 . Once pressure within blowdown system  124  and second emissions inlet conduit  168  have bled down to the reduced pressure, HP blowdown valve  174  may be closed to force the blowdown emissions to flow through VRU  156  for processing rather than bypassing VRU  156  via blowdown bypass conduit  170 . In this manner, high pressure emissions from blowdown system  124  may be processed by the same VRU  156  used to process low pressure emissions from either of the seal system  122  or vent system  123  of compressor package  100 , eliminating the need for separate VRUs  156  and/or separate emissions management modules  150  to service the same compressor package  100 . 
     It may be understood that the configuration of emissions management module  150  (e.g., the configuration, placement, and/or arrangement of VRU  156 , conduits  162 ,  164 , valves  172 ,  174 , etc.) shown in  FIG.  5    is only exemplary and in other embodiments the configuration of emissions management module  150  may vary. For example, in other embodiments, emissions management module  150  may include components not shown in  FIG.  5    and/or may not include at least some of the features shown in  FIG.  5   . 
     Referring now to  FIG.  6   , another embodiment of an emissions management module  200  of a natural gas system is shown. The emissions management module  200  shown in  FIG.  6    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems). Emissions management module  200  includes features in common with emissions management module  150  shown in  FIG.  5   , and shared features are labeled similarly. 
     Particularly, emissions management module  200  does not include the onboard power source  154  of emissions management module  150 . Instead, emissions management module  200  is powered by an external power source (indicated schematically by box  202  in  FIG.  6   ) not located on the support structure  152  thereof. External power source  202  may be provided by the natural gas system  10  and thus may power other components of system  10 . For example, external power source  202  may comprise an electrical power grid to which the emissions management module  200  is electrically connected. Such a configuration may be advantageous for eliminating the emissions produced by power source  154  in applications where such external electrical power is available. Alternatively, external power source  202  may comprise an offboard electrical generator or other power system for providing power to the emissions management module  200 . The power received by emissions management module  200  from external power source may be 460V three-phase electrical power; however, the power supplied to emissions management module  200  by external power source  202  may vary depending on the given application. 
     Referring now to  FIG.  7   , another embodiment of a compressor package  250  and an emissions management module  300  of a natural gas system are shown in greater detail. The compressor package  250  shown in  FIG.  7    may comprise one or more of the compressor packages  30  while the emissions management module  300  shown in  FIG.  7    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems). Compressor package  250  and emissions management module  300  includes features in common with compressor package  100  and emissions management module  150 , respectively, shown in  FIG.  5   , and shared features are labeled similarly. 
     Particularly, in this exemplary embodiment, compressor package  250  includes an electrical generator  252  coupled to the driveshaft  114  of cooling system  110  by a mechanical linkage  254 . Linkage  254  may comprise belt(s), chain(s), gear train(s), and/or other mechanisms for transferring mechanical energy from driveshaft  114  to an input or drive gear  256  of electrical generator  252 . In this configuration, rotation of the driveshaft  114  of cooling system  110  (driven by the operation of driver  102  of compressor package  100 ) rotates the drive gear  256  of generator  252 , causing generator  252  to output electrical power. Generator  252  is electrically connected to the emissions management module  300  (which does not include onboard power source  154 ) whereby generator  252  may power the emissions management module  300 , including the VRU  156  and/or air system  180  thereof. The power received by emissions management module  300  from generator  252  may be 460V three-phase electrical power; however, the power supplied to emissions management module  300  by generator  252  may vary depending on the given application. In this manner, the emissions provided by the onboard power source  154  of emissions management module  150  may be eliminated while also not relying on external power (e.g., an electrical power grid) which may be unavailable in at least some applications. Additionally, in this exemplary embodiment, emissions management module comprises a battery system  302  chargeable by electrical generator  252 . Battery system  302  may power emissions management module  300  when the associated compressor package  250  is shut-down. 
     Referring now to  FIG.  8   , another embodiment of an emissions management module  350  of a natural gas system is shown. The emissions management module  350  shown in  FIG.  8    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems). Emissions management module  350  includes features in common with emissions management module  150  shown in  FIG.  5   , and shared features are labeled similarly. Particularly, rather than an electrically powered VRU such as the VRU  156  of emissions management module  150  shown in  FIG.  5   , emissions management module  350  includes a natural gas powered VRU  352  which does not rely on an electrical power source such as power source  154  for operation. 
     Instead, in this exemplary embodiment, VRU  352  comprises a gas circulator  353  including a suction tank or vessel  354  and a fluid powered gas ejector  356  configured to compress emissions captured from compressor package  100  to a process suction (e.g., suction conduit  22 ) of the compressor package  100 . Particularly, gas ejector  356  of gas circulator  353  includes a nozzle-diffuser assembly  358  which receives both captured emissions from suction tank  354  and a motive fluid from discharge conduit  24  via a motive fluid conduit  360  extending between discharge conduit  24  and gas ejector  356 . Gas ejector  356  may also be referred to as a venturi jet, a jet mixer, an aspirator, and a gas eductor. In other embodiments, the motive fluid provided to gas ejector  356  may be sourced from locations in addition to or other than discharge conduit  24 . For example, the motive fluid supplied to gas ejector  356  may be provided from a downstream pipeline (e.g., downstream pipeline  14  shown in  FIGS.  1 ,  2   ), a discharge of the natural gas system or facility in which emissions management module  350  is located, and/or from some other source or location. 
     In this exemplary embodiment, the nozzle-diffuser assembly  358  includes an upstream nozzle, a downstream diffuser, and a throat positioned between the nozzle and diffuser. In this configuration, the high-pressure natural gas provided to ejector  356  by discharge conduit  24  powers the compression of the captured emissions through nozzle-diffuser assembly  358  of gas ejector  356  and into the suction conduit  22 . Thus, by powering ejector  356  by the high-pressure natural gas discharged by compressor package  100 , VRU  352  need not employ a powered rotary or reciprocating compressor for driving the compression of captured emissions through emissions management module  350 . This avoids the requirement of supplying emissions management module  350  with a potentially emissions-producing high voltage electrical power source (e.g., a power source providing 400+V). Instead, only the low-voltage control panel  190  may need be electrically powered in this exemplary embodiment, where the limited power requirements of control panel  190  may be satisfied by batteries of compressor package  100 . However, in other embodiments, the emissions management module  350  may include both gas ejector  356  and a rotary or reciprocating compressor. Additionally, in some embodiments, emissions management module  350  may include a plurality of gas ejectors  356  or a combination of a rotary or reciprocating compressor and a plurality of gas ejectors  356 . 
     Referring now to  FIG.  9   , another embodiment of an emissions management module  400  of a natural gas system are shown in greater detail. The emissions management module  400  shown in  FIG.  9    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems such as systems). Emissions management module  400  includes features in common with emissions management module  350  shown in  FIG.  8   , and shared features are labeled similarly. 
     In this exemplary embodiment, emissions management module  400  comprises a natural gas powered VRU  402  which includes a pair of fluid or gas circulators  404  and  406  for capturing and directing different types of emissions from the compressor package  100 . Each of the gas circulators  404  and  406  comprises a separate or dedicated gas ejector  356  and nozzle-diffuser assembly  358 . Additionally, gas circulator  406  comprises a suction tank  354 . It may be understood that in other embodiments the configuration of gas circulator  404  and/or  406  may vary from that shown in  FIG.  9   . A first gas circulator  404  of the pair of gas circulators  404 ,  406  corresponds to a high-pressure circuit of the VRU  402  while a second gas circulator  406  of the pair of gas circulators  404 ,  406  corresponds to a low-pressure circuit of the VRU  402  which receives emissions from compressor package  100  that are generally of a lower pressure than the emissions received by the high-pressure circuit of VRU  402 . For example, the first or high-pressure gas circulator  404  of VRU  402  may receive blowdown emissions from compressor package  100  while the second or low-pressure gas circulator  406  may receive packing or other generally low-pressure emissions from compressor package  100 . In this configuration, VRU  402  includes a high-pressure circuit comprising the high-pressure gas circulator  404  and a low-pressure circuit, separate from the high-pressure circuit, comprising the low-pressure gas circulator  406 . Providing VRU  402  with two distinct emissions recovery circuits (the high- and low-pressure circuits thereof) may allow for the low-pressure circuit of VRU  402  to be maintained at negative or vacuum pressure, preventing captured emissions circulating through the low-pressure circuit of VRU  402  from escaping to the surrounding atmosphere. Indeed, in some embodiments VRU  402  is configured to maintain second emissions inlet conduit  168  under a vacuum such that second emissions inlet conduit  168  and the systems of compressor package  100  in fluid communication therewith (e.g., seal system  122 , vent system  123 ) may not be exposed to positive pressure. 
     The ability to maintain the low-pressure circuit of VRU  402  under vacuum may allow compressor package  100  to operate a closed vent packing system which, under some regulatory authorities, may permit less frequent inspecting of the compressor package  100  and thus a reduction in costs associated with the operation of compressor package  100 . Additionally, a greater variety of emissions including, for example, emissions associated with instrument gas (which cannot be exposed to positive pressure) of compressor package  100  may be captured by the low-pressure circuit of VRU  402  when the low-pressure circuit is maintained under vacuum. 
     In this exemplary embodiment, motive fluid conduit  360  branches into a first branch conduit  361  associated with the high-pressure circuit of VRU  402  and a second branch conduit  363  associated with the low-pressure circuit of VRU  402 , where a corresponding branch valve  362  and  364  is disposed along the branch conduits  361  and  363 , respectively. In this arrangement, motive fluid in the form of pressurized natural gas from discharge conduit  24  may be supplied separately to the high-pressure and low-pressure circuits of VRU  402 . Additionally, branch valves  362  and  364  permit the high-pressure and low-pressure circuits of VRU  402  to be selectably isolated from discharge conduit  24 . In this exemplary embodiment, pressurized natural gas is supplied from a first branch conduit  361  of the pair of branch conduits  361 ,  363  to the high-pressure gas circulator  404  while pressurized natural gas may be supplied from a second branch conduit  363  of the pair of branch conduits  361 ,  363  to the gas ejector  356  of low-pressure gas circulator  406 ; however, it may be understood that in other embodiments the manner in which the pressurized natural gas is supplied to gas circulators  404  and  406  may vary from the arrangement shown in  FIG.  9   . 
     In this exemplary embodiment, first emissions inlet conduit  166  is routed from the compressor package  100  to the low-pressure gas circulator  406  and thus is associated with the low-pressure circuit of VRU  402 . Particularly, first emissions inlet conduit  166  connects with the suction tank  354  of the low-pressure gas circulator  406  to route low-pressure emissions from the compressor package  100  to the low-pressure gas circulator  406 . Additionally, in this exemplary embodiment, second emissions inlet conduit  168  is routed from the compressor package  100  to the high-pressure gas circulator  404  and thus is associated with the high-pressure circuit of VRU  402 . Specifically, second emissions inlet conduit  168  connects to the gas ejector  356  of the high-pressure gas circulator  404  to route high-pressure emissions from the compressor package  100  to the high-pressure gas circulator  404 . It may be understood that the manner in which first emissions inlet conduit  166  is routed to the low-pressure gas circulator  406  and the manner in which second emissions inlet conduit  168  is routed to high-pressure gas circulator  404  may vary from the arrangement shown in  FIG.  9   . 
     Further, in this exemplary embodiment, discharge conduit  164  is routed in parallel from the discharge of the nozzle-diffuser assembly  358  of each gas circulator  404 ,  406  to the suction conduit  22  associated with the compressor package  100 . However, it may be understood that in other embodiments the captured emissions discharged from the high- and/or low-pressure circuits of VRU  402  may be routed to locations other than suction conduit  22 , including the fuel system of compressor package  100 . 
     As an example, and referring now to  FIG.  10   , another embodiment of an emissions management module  500  of a natural gas system is shown along with an embodiment of a compressor package  450  from which the emissions management module  500  captures emissions. As shown in  FIG.  10   , compressor package  450  includes a fuel gas conditioner  82  as described above which is connected to a fuel header  92  of fuel system  91  of a natural gas system (e.g., fuel system  91  of the natural gas system  70  shown in  FIG.  3   ). 
     The emissions management module  500  shown in  FIG.  10    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems). Additionally, emissions management module  500  includes features in common with emissions management module  400  shown in  FIG.  9   , and shared features are labeled similarly. Particularly, emissions management module  500  is similar to module  400  except that only the emissions discharged from the high-pressure circuit of VRU  402  thereof are routed by discharge conduit  164  to the suction conduit  22 . In this exemplary embodiment, the emissions discharged from the low-pressure circuit of the VRU  402  of emissions management module  500  are routed by a second or fuel discharge conduit  165  from the discharge of the nozzle-diffuser assembly  358  of the low-pressure gas circulator  406  to the fuel header  92 , where at least some of the emissions may be directed from the fuel header  92  to the fuel gas conditioner  82  of compressor package  450  prior to being consumed by the driver  102  of compressor package  450 . 
     While in this exemplary embodiment the high-pressure circuit of the VRU  402  of emissions management module  500  is connected to the suction conduit  22  while the low-pressure circuit of VRU  402  is connected to the fuel system  91 , in other embodiments the arrangement of the high- and low-pressure circuits of VRU  402  may be reversed, with the high-pressure circuit of VRU  402  connected to the fuel system  91  and the low-pressure circuit of VRU  402  connected to suction conduit  22 . Alternatively, both the high-pressure circuit and low-pressure circuit of VRU  402  may be connected to the fuel system  91 . 
     Referring now to  FIG.  11   , another embodiment of an emissions management module  550  of a natural gas system is shown. The emissions management module  550  shown in  FIG.  11    may comprise one or more of the emissions management modules  40  of the natural gas system  10  shown in  FIG.  1    or the natural gas systems  50 ,  70 , and  95  shown in  FIGS.  2 - 4   , respectively (or other natural gas systems). Additionally, emissions management module  550  includes features in common with emissions management modules  150  and  400  shown in  FIGS.  5  and  9   , respectively, and shared features are labeled similarly. 
     Particularly, in this exemplary embodiment, emissions management module  550  comprises a VRU  552  including a high-pressure circuit comprising the high-pressure gas circulator  404 , and a low-pressure circuit that is separate from the high-pressure circuit and comprises a low-pressure gas circulator  556  that is different in configuration from the low-pressure gas circulator  406  (shown in  FIG.  9   ) described above. Specifically, in this exemplary embodiment, low-pressure gas circulator  556  comprises motor  158  and compressor  160 , where motor  158  is powered by onboard power source  154  as described in greater detail above. It may be understood that while in this exemplary embodiment the low-pressure gas circulator  556  comprises compressor  160 , in other embodiments, the high-pressure gas circulator  404  of VRU  552  may instead comprise the compressor  160  while the low-pressure gas circulator  556  may instead comprise the gas ejector  356 . 
     Additionally, in this exemplary embodiment, both the low-pressure and high-pressure circuits of VRU  552  discharge into the suction conduit  22  associated with compressor package  100  through the discharge conduit  164  which is connected in parallel to the discharge of both the high-pressure gas circulator  404  and the low-pressure gas circulator  556  of the VRU  552  of emissions management module  550 . It may be understood of course that the emissions discharged from high-pressure gas circulator  404  and/or low-pressure gas circulator  556  may be directed to locations other than the suction conduit  22 . 
     As an example, and referring now to  FIG.  12   , another embodiment of an emissions management module  600  of a natural gas system is shown. The emissions management module  600  shown in  FIG.  12    may comprise one or more of the emissions management modules  40  and  72  shown in  FIGS.  1 - 4   . Additionally, emissions management module  600  includes features in common with emissions management module  550  shown in  FIG.  11   , and shared features are labeled similarly. Particularly, emissions management module  600  is similar to the module  550  of  FIG.  11    except that emissions discharged from the high-pressure gas circulator  404  of the VRU  552  of emissions management module  600  is routed to the suction conduit  22  by discharge conduit  164  while emissions discharged from the low-pressure gas circulator  556  (comprising compressor  160  in this exemplary embodiment) is routed to fuel header  92  by the fuel discharge conduit  165 . It may be understood of course that in other embodiments the high-pressure gas circulator  404  of VRU  552  may discharge to the fuel header  92  while the low-pressure gas circulator  556  may discharge to the suction conduit  22 . 
     Referring to  FIG.  13   , an embodiment of a method  650  for capturing emissions from a compressor package of a natural gas system is shown. Beginning at block  652 , method  650  comprises transporting a flow of natural gas from a process suction conduit of the natural gas system to a compressor package of the natural gas system. In some embodiments, block  652  comprises transporting a flow of natural gas from the suction header  16  and/or suction conduit  22  of the natural gas system  10  of  FIG.  1    (or of natural gas systems  50 ,  70 , and  95  of  FIGS.  2 - 4   , respectively) to one of the compressor packages  30 . In certain embodiments, block  652  may comprise transporting the flow of natural gas to one of the compressor packages  100 ,  250  shown in  FIGS.  5 - 8   , respectively. 
     At block  654 , method  650  comprises increasing a pressure of the flow of natural gas received from the suction conduit by the compressor package. In some embodiments, block  654  comprises increasing a pressure of the flow of natural gas received from the suction header  16  and/or suction conduit  22  by the compressor package  30 . In certain embodiments, block  654  comprises increasing the pressure of the flow of natural gas by the compressor package  100  shown in  FIGS.  5 ,  6 , and  8   , and/or by the compressor package  250  shown in  FIG.  7   . At block  656 , method  650  comprises discharging the flow of natural gas from the compressor package to a discharge conduit of the natural gas system. In some embodiments, block  656  comprises discharging the flow of natural gas from compressor package  100  shown in  FIGS.  5 ,  6 , and  8   , and/or the compressor package  250  shown in  FIG.  7    to the discharge conduit  24 /discharge header  18 . 
     At block  658 , method  650  comprises capturing emissions from the compressor package by an emissions management module of the natural gas system. In some embodiments, block  658  comprises capturing emissions from the compressor packages  30  by the emissions management modules  40  shown in  FIG.  1    and  FIG.  2   . In some embodiments, block  658  comprises capturing emissions from the compressor package  100  by any of the emissions management modules  150 ,  200 ,  350 ,  400 , and  550  shown in  FIGS.  5 ,  6 ,  8 ,  9 , and  11   , respectively. In certain embodiments, block  658  comprises capturing emissions from the compressor package  250  by the emissions management module  300  shown in  FIG.  7   . In some embodiments, block  658  comprises capturing emissions from the compressor package  450  by any of the emissions management modules  500  and  600  shown in  FIGS.  10  and  12   , respectively. 
     At block  660 , method  650  comprises circulating the captured emissions by a vapor recovery unit (VRU) of the emissions management module to a component of the natural gas system. In some embodiments, block  660  comprises circulating the captured emissions to the suction conduit of the natural gas system. In some embodiments, block  660  comprises circulating the captured emissions to a driver of the compressor package such as a fuel filter of the driver whereby the captured emissions may be consumed as fuel by the driver. In some embodiments, block  660  comprises circulating the captured emissions to a hydrocarbon processing component of the natural gas system separate from the compressor package and which processes a process gas (e.g., natural gas) of the natural gas system. 
     In certain embodiments, block  660  comprises circulating the captured emissions by the VRU  41  of the emissions management module  40  shown in  FIG.  1    and  FIG.  2    to the suction header  16  and/or suction conduit  22 . In some embodiments, block  660  comprises circulating the captured emissions by the VRU  156  of the emissions management module  150  shown in  FIG.  5    to the suction header  16  and/or suction conduit  22 . In certain embodiments, block  660  comprises circulating the captured emissions by the VRU  156  of the emissions management module  200  shown in  FIG.  6    to the suction header  16  and/or suction conduit  22 . In some embodiments, block  660  comprises circulating the captured emissions by the VRU  156  of the emissions management module  300  shown in  FIG.  7    to the suction header  16  and/or suction conduit  22 . In certain embodiments, block  660  comprises circulating the captured emissions by the VRU  352  of the emissions management module  350  shown in  FIG.  8    to the suction header  16  and/or suction conduit  22 . In some embodiments, block  660  comprises circulating the captured emissions by the VRU  402  of the emissions management module  400  shown in  FIG.  9    to the suction header  16  and/or suction conduit  22 . In some embodiments, block  660  comprises circulating the captured emissions by the VRU  552  of the emissions management module  550  shown in  FIG.  11    to the suction header  16  and/or suction conduit  22 . 
     While exemplary embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. For example, the relative dimensions of various parts, the materials from which the various parts are made, and other parameters can be varied. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.