Systems and methods for a multi-source fuel valve

Abstract

A fuel pressure regulator includes an outlet line to supply fuel to a consumer at a supply pressure. A first fuel line couples to a first fuel source having fuel at a first pressure. A first pressure regulator reduces the fuel from the first pressure to the supply pressure. A second fuel line couples to a second fuel source having fuel at a second pressure. A second pressure regulator reduces the fuel from the first pressure to a third pressure that is between the second pressure and the supply pressure. In a first mode, fuel is supplied from the first fuel source to the outlet line and the second fuel source is blocked. In a second mode, fuel is supplied from the second fuel source to the outlet line and the first fuel source is blocked.

Description

Non-Provisional Patent Application 154839.000103SYSTEMS AND METHODS FOR A MULTI-SOURCE FUEL VALVECROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 762,971, filed February 25, 2025, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] The present disclosure relates to valves arrangements for fuel systems. More specifically, valve systems can be used to control a pressure of fuel that is supplied to a prime mover from a plurality of fuel sources.SUMMARY

[0003] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0004] According to one aspect of the present disclosure, a generator can include a housing, an engine positioned within the housing and configured to receive fuel at a supply pressure, and a fuel supply valve supported by the housing. The fuel supply valve can include a main supply line coupled to the engine, a first supply line to couple a first fuel source to the main supply line, a first pressure regulator positioned along the first supply line to reduce the first fuel source from a first pressure to the supply pressure, a second supply line to couple a second fuel source to the main supply line, a second pressure regulator positioned along the second supply line to reduce the second fuel source from a second pressure to a third pressure, the second pressure being greater than the first pressure, and a third pressure regulator positioned along the second supply line between the second pressure regulator and the main supply line to reduce the second fuel source from the third pressure to the supply pressure.

[0005] In some examples, the supply pressure can be less than about 1 psi.

[0006] In some examples, the first pressure can be less than about 5 psi and the second pressure1QBU01072417.1Non-Provisional Patent Application 154839.000103can be less than about 3600 psi.

[0007] In some examples, the third pressure can be less than about 85 psi.

[0008] In some examples, the first fuel source can be a municipal natural gas mains and the second fuel source can be a compressed natural gas tank.

[0009] In some examples, the fuel supply valve can include a heat exchanger that receives coolant from the engine to heat the second pressure regulator.

[0010] In some examples, the fuel supply valve can further include a first shutoff valve positioned between the first supply line and the main supply line, and a second shutoff valve positioned between the second supply line and the main supply line. The first shutoff valve can be open and the second shutoff valve can be closed in a first supply configuration, and the first shutoff valve can be closed and the second shutoff valve can be opened in a second supply configuration.

[0011] In some examples, the first shutoff valve and the second shutoff valve can be manual shutoff valves.

[0012] In some examples, the generator can further include a pressure sensor to measure the second pressure.

[0013] In some examples, the generator can further include an electronic controller in communication with the pressure sensor and configured to block the second supply line when the second pressure reaches a minimum threshold pressure.

[0014] In some examples, the electronic controller can shut off the engine when the second pressure reaches the minimum threshold pressure.

[0015] In some examples, the first shutoff valve and the second shutoff valve can be electronically-controlled shutoff valves and the electronic controller can transition the fuel supply valve from the second supply configuration to the first supply configuration when the second pressure reaches the minimum threshold pressure.

[0016] In some examples, the fuel supply valve can be positioned within the housing.

[0017] According to another aspect of the present disclosure, a fuel pressure regulator can include an outlet line to supply fuel to an engine at a supply pressure, a first fuel line configured to couple to a first fuel source having fuel at a first pressure, a first pressure regulator coupled between the first fuel line and the outlet line to reduce the fuel from the first pressure to the supply pressure, a second fuel line configured to couple to a second fuel source having fuel at a second pressure that2QBU01072417.1Non-Provisional Patent Application 154839.000103is greater than the first pressure, a second pressure regulator coupled between the first fuel line and the outlet line to reduce the fuel from the first pressure to a third pressure that is between the second pressure and the supply pressure, and a control system to selectively operate the fuel pressure regulator in each of a first mode, wherein fuel is supplied from the first fuel source to the outlet line and the second fuel source is blocked, and a second mode, wherein fuel is supplied from the second fuel source to the outlet line and the first fuel source is blocked.

[0018] In some examples, the fuel pressure regulator can further include a heating element to heat the second pressure regulator.

[0019] In some examples, the heating element can be a heat exchanger.

[0020] In some examples, the fuel pressure regulator can further include a third pressure regulator coupled between the second pressure regulator and the outlet line to reduce the fuel from the third pressure to the supply pressure.

[0021] In some examples, the third pressure can be equal to the first pressure.

[0022] In some examples, in the second mode, the control system can be configured to block the second fuel source when the second pressure is below a minimum threshold pressure.

[0023] In some examples, the control system can include a first shutoff valve to selectively block the first fuel line and a second shutoff valve to selectively block the second fuel line.

[0024] According to yet another aspect of the present disclosure, a method of supplying fuel to an engine for a generator from multiple sources can include, in a first mode, coupling a first fuel supply line to a main supply line to supply the fuel from a first fuel source to the engine at a supply pressure, the first fuel supply line including a first pressure regulator to reduce the fuel from the first fuel source from a first pressure to the supply pressure, and in a second mode, coupling a second fuel supply line to the main supply line to supply the fuel from a second fuel source to the engine at the supply pressure, the second fuel supply line including a second pressure regulator to reduce the fuel from the second fuel source from a second pressure to a third pressure and a third regulator to reduce the fuel from the second fuel source from the third pressure to the supply pressure.

[0025] In some examples, the method can further include, in the first mode, decoupling the second fuel supply line from the main supply line, and in the second mode, decoupling the first fuel supply line from the main supply line.3QBU01072417.1Non-Provisional Patent Application 154839.000103BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The disclosure will be better understood, and features, aspects, and advantages will become apparent when consideration is given to the following detailed description thereof. Such detailed description references to the following drawings.

[0027] FIG. l is a diagrammatic view of a generator system including a fuel valve for controlling a supply of fuel to a generator from a plurality of fuel sources, according to aspects of the disclosure.

[0028] FIG. 2 is a perspective view of a generator system in accordance with FIG. 1.

[0029] FIG. 3 is a top, front, and left isometric view of the fuel valve of FIG. 1.

[0030] FIG. 4 is a top, rear, and right isometric view of the fuel valve of FIG. 1.

[0031] FIG. 5 is a top, rear, and right isometric view of another arrangement of the fuel valve of FIG. 1, according to aspects of the disclosure.DETAILED DESCRIPTION

[0032] The following discussion is presented to enable a person skilled in the art to make and use aspects of the present disclosure. Various modifications to the illustrated configurations will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other configurations and applications without departing from aspects of the present disclosure. Thus, aspects of the present disclosure are not intended to be limited to configurations shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected configurations and are not intended to limit the scope of the present disclosure. Skilled artisans will recognize the non-limiting examples provided herein have many useful alternatives and fall within the scope of the present disclosure.

[0033] Before any aspects of the present disclosure are explained in detail, it is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The present disclosure is capable of other configurations and of being practiced, or of4QBU01072417.1Non-Provisional Patent Application 154839.000103being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings and may also indicate fluid couplings.

[0034] As used herein, the terms “downstream” and “upstream” herein are terms that indicate direction relative to the flow of a fluid. The term “downstream” corresponds to the direction of fluid flow, while the term “upstream” refers to the direction opposite or against the direction of fluid flow.

[0035] As also used herein, unless otherwise defined or limited, ordinal numbers are used herein for convenience of reference based generally on the order in which particular components are presented for the relevant part of the disclosure. In this regard, for example, designations such as “first,” “second,” etc., generally indicate only the order in which the relevant component is introduced for discussion and generally do not indicate or require a particular spatial arrangement, functional or structural primacy or order.

[0036] Generators typically include an internal combustion engine that consumes fuel and produces electrical energy. In some cases, generators (e.g., an internal combustion engine) can be configured to run on gaseous fuel sources, for example, natural gas, propane, etc. Gaseous fuel sources are preferably supplied at a specific pressure range (e.g., supply pressure) in order to ensure fuel is delivered into a generator for combustion.

[0037] However, gaseous fuels can be stored or supplied in a variety of ways, typically at varying amounts of pressure. For example, low-pressure natural gas can be supplied via municipal gas mains, whereas medium- or high-pressure propane or natural gas can be supplied by stationery or mobile tank systems, e.g., bottle storage, tube trailers, etc. In some examples, low-pressure fuel can be supplied between 0 psi and about 30 psi, medium-pressure fuel can be supplied between about 30 psi and about 150 psi, and high-pressure fuel can be supplied at greater than about 150 psi. Such ranges are exemplary and other ranges for low-, medium-, and high-pressure are possible.5QBU01072417.1Non-Provisional Patent Application 154839.000103

[0038] In many cases, the pressure of the fuel supply can be greater than what can be supplied to the generator. Thus, to provide fuel gas from the fuel gas supply to the object at the object’s working pressure, gas valve assemblies include, among other things, pressure regulators to lower the pressure of the fuel gas on delivery from the fuel gas supply to the object. However, current gas valve assemblies are typically unable to regulate both high-pressure fuel gas supplies and low-pressure gas fuel supplies in the same gas valve assembly. Furthermore, since installation of gas valve assemblies is difficult and gas valve assemblies take up significant amounts of space, there is a need for a gas valve assembly that can allow both high-pressure fuel gas supplies and low-pressure fuel gas supplies. Such systems also allow for generator operation in scenarios where some type of fuel sources may not be available (e.g., gas mains in remote or emergency areas), or for optimizing long- or short-term generator usage (e.g., for temporary or long-term vehicle charging, or as a backup generator).

[0039] Multi-source fuel valves (e.g., valve systems) according to the present disclosure can address some or all of these problems by allowing fuel stored at varying pressures or supplied by different sources to be regulated to a desired supply pressure and selectively coupled to a generator or other combustion device (e.g., a furnace or other consumer). For example, a fuel valve according to the disclosure can include a first supply line (e.g., a first inlet or fuel line) to couple to a first fuel source and a second supply line (e.g., a second inlet or fuel line) to couple to a second fuel source. The first fuel source can be at a lower pressure than the second fuel source. Correspondingly, a set of pressure regulators can be used to reduce the pressure of fuel from the first fuel source and the second fuel source to the desired supply pressure, which is supplied to the consumer (e.g., the generator) via a main supply line (e.g., an outlet line of the valve). In some examples, multiple regulators can be arranged in series along a supply line to more effectively regulate pressure when the pressure differential between a source pressure and the supply pressure is above a threshold differential. In some examples, the fuel valve can include a heater to prevent freezing of the pressure regulator or other valve system components. A heater can be a resistive heater or a heat exchanger. In some cases, a control system (e.g., a manual shutoff valve or electronically controlled shutoff valve) can selectively switch the valve system between a first mode to operate the consumer on the first fuel source and a second mode to operate the consumer on the second fuel source.6QBU01072417.1Non-Provisional Patent Application 154839.000103

[0040] FIGS. 1-5 illustrate an example system that incorporates a valve system according to aspects of the disclosure. The illustrated system is configured as a generator 100, though other implementations are possible, including portable power supplies, permanent power installations, backup power systems, or mobile charging stations. The generator 100 includes a valve system 102 that enables an engine 104 to selectively operate on a plurality of fuel sources, thereby providing operational flexibility across different deployment scenarios and fuel availability conditions. The engine 104 is positioned within a housing 106, which can be configured as a transport container, weatherproof enclosure, or another type of protective structure suitable for the intended application environment. The valve system 102 can be mounted on or within the housing 106, facilitating transport and installation of the generator 100 as a self-contained unit. While the generator 100 represents one implementation of the valve system 102, skilled artisans will appreciate that the valve system 102 can be adapted for use with other fuel-consuming devices, such as furnaces, industrial burners, or other combustion equipment, and can be configured to deliver fuel at various supply pressures (e.g., end-of-system pressures) appropriate for the specific consumer requirements.

[0041] While the illustrated example depicts a generator 100 with an internal combustion engine 104, skilled artisans will appreciate that the valve system 102 can be adapted for use with a wide variety of fuel-consuming devices beyond internal combustion engines. For example, the valve system 102 can be configured to supply fuel to fuel cells, which convert chemical energy directly into electrical energy through electrochemical reactions. In some examples, the valve system 102 can supply fuel to gas turbines, which can be used in power generation applications ranging from small-scale distributed generation to larger industrial installations. The valve system 102 can also be adapted for use with boilers, furnaces, or other thermal processing equipment that consume gaseous fuels for heating applications. The valve system 102 can also be configured to supply fuel to absorption chillers, industrial dryers, kilns, or other process equipment that utilizes gaseous fuels.

[0042] Referring to FIG. 2, it is appreciated that the generator 100 can be provided in a variety of configurations and can include one or more generators, each having one or more valve systems. In some examples, the generator 100 can be configured as a mobile generator. For instance, the valve system 102 of the generator 100 can be mounted on a trailer or other transport platform to7QBU01072417.1Non-Provisional Patent Application 154839.000103allow the generator 100 to be moved between deployment locations. The valve system 102 can also be configured in different sizes or capacities, enabling an operator to select a configuration appropriate for a particular application. Additionally, it is appreciated that the generator 100 can be supplied by one or more fuel sources. In some examples, a fuel source can be dedicated to a particular valve system 102, while in other examples a fuel source can be shared among multiple valve systems 102 to accommodate operational needs or to optimize fuel distribution within the generator system.

[0043] As mentioned above, a valve system can regulate pressure of a fuel supplied from a plurality of fuel sources. In the illustrated example, the valve is configured to supply and regulate pressure from a first fuel source 108 or a second fuel source 110 that is different from the first fuel source 108 (e.g., different in pressure, supply type, chemical composition, etc.). Here, the first fuel source 108 is configured as a low-pressure fuel, such as a natural gas main. The fuel from the first fuel source 108 can be supplied at a first pressure. In the illustrated example, the first pressure can be less than about 5 pounds per square inch (psi). In other examples, the first pressure can be different, for example, to be between about 1 psi and about 10 psi, between about 5 psi and about 50 psi, or between about 100 psi and about 200 psi, or another pressure as determined by the specific application. The second fuel source 110 is configured as a high-pressure fuel, such as compressed natural gas. The fuel from the second fuel source 110 can be supplied at a second pressure that is different (e.g., higher) than the first pressure. In the illustrated example, the second pressure can be about 3600 (psi). In other examples, the second pressure can be different, for example, to be between about between about 100 psi and about 200 psi, between about 500 psi and about 1000 psi, between about 1500 psi and 3000 psi, between 3000 psi about 5000 psi, or another pressure as determined by the specific application.

[0044] In other examples, other characteristics of the fuel can be different, or more than two fuel sources can be utilized. For example, a first fuel can be liquid propane supplied at a relatively low pressure, while a second fuel can be compressed natural gas stored at a substantially higher pressure. In further examples, a third fuel source could be incorporated, such as biogas or hydrogen, with corresponding pressure regulation components to accommodate the specific pressure characteristics of each additional fuel type. Correspondingly, fuel sources can be provided, stored, or delivered for use in different configurations to meet the operational, economic,8QBU01072417.1Non-Provisional Patent Application 154839.000103or logistical needs of a particular application. In the illustrated examples, mains gas from the first fuel source 108 can be preferentially used when natural gas commodity prices are favorable, when utility infrastructure is reliable, or when mains gas is readily available at the deployment location. Conversely, gas from the second fuel source 110, such as compressed natural gas stored in tanks or tube trailers, can be utilized when natural gas commodity prices are elevated, when mains gas infrastructure is unavailable or unreliable, or during specific operational scenarios such as utility outages, deployment in remote areas lacking pipeline infrastructure, operation as backup power in emergency relief zones following natural disasters, or temporary installations at construction sites or special events. The ability to switch between fuel sources also provides operational continuity, allowing the generator 100 to continue operating even when one fuel source becomes depleted or inaccessible. Thus, the valve system 102 has advantages over conventional single-source valve systems by enabling multiple fuel sources having different pressure characteristics to be utilized to operate the generator 100, either separately in distinct operating modes or simultaneously when operational requirements permit.

[0045] In addition to the fuel sources described above, the valve system 102 can be configured to accommodate a wide variety of other gaseous fuel types and delivery configurations. For example, the valve system 102 can be adapted to receive landfill gas, which is produced by the decomposition of organic waste in landfills and typically contains methane along with carbon dioxide and other trace gases. In some examples, the valve system 102 can be configured to receive syngas (synthesis gas), which can be produced from coal, biomass, or other carbonaceous materials through gasification processes. The valve system 102 can also be adapted to receive liquefied natural gas (LNG) that has been vaporized, renewable natural gas (RNG) produced from organic waste sources, or hydrogen gas for use in hydrogen-fueled applications. In further examples, the valve system 102 can be configured to receive digester gas from wastewater treatment facilities, coalbed methane, or other unconventional gas sources. Correspondingly, fuel sources can be provided through various storage and delivery systems beyond the municipal mains and compressed gas tanks described above. For example, fuel can be supplied from cryogenic storage vessels for liquefied gases, from on-site gasification or reforming equipment, from pipeline interconnections with industrial gas networks, or from mobile refueling vehicles. In some cases, fuel can be supplied from renewable energy systems that produce hydrogen through electrolysis9QBU01072417.1Non-Provisional Patent Application 154839.000103or from biogas digesters that process agricultural or food waste. The valve system 102 can include appropriate fittings, connections, and safety devices to accommodate the specific characteristics of each fuel type and delivery system.

[0046] In some cases, a valve system can be operated in a plurality of modes to control which of a plurality of fuel sources is supplied to a generator or other fuel-consuming device. As described in greater detail below, a control system (e.g., a manual or electronically controlled control system) can be operated to transition the valve system between operating modes based on operational requirements, fuel availability, economic considerations, or other factors. In the illustrated example, the valve system 102 can be operated in a first mode to supply and regulate fuel from the first fuel source 108 to run the generator 100 while blocking the second fuel source 110 from delivering fuel to the engine 104. The valve system 102 can also be operated in a second mode to supply and regulate fuel from the second fuel source 110 to run the generator 100 while blocking the first fuel source 108 from delivering fuel to the engine 104. In some cases, the valve system 102 can also operate in a third mode where fuel is supplied and regulated from both the first fuel source 108 and the second fuel source 110 simultaneously, which can be useful when demand exceeds the capacity of a single fuel source or when transitioning between fuel sources during operation. Additionally, the valve system 102 can operate in a fourth mode (e g., an off mode or shutdown mode) where fuel from both the first fuel source 108 and the second fuel source 110 is blocked from the generator 100, such as during maintenance, storage, or when the generator 100 is not in use. The ability to selectively operate in these different modes provides operational flexibility and allows the generator 100 to adapt to varying conditions and requirements.

[0047] In the first mode or the third mode, fuel can be supplied from the first fuel source 108 to the engine 104 of the generator 100 (e.g., or another consumer such as a furnace, industrial burner, or other combustion equipment) along a first supply line 112 to a main supply line 114. The first supply line 112 provides a dedicated flow path for fuel from the first fuel source 108 and includes pressure regulation components to condition the fuel before delivery to the main supply line 114. In the second mode or the third mode, fuel can be supplied from the second fuel source 110 to the engine 104 of the generator 100 (e.g., or another consumer) along a second supply line 116 to the main supply line 114. The second supply line 116 provides a separate dedicated flow path for fuel from the second fuel source 110 and includes its own pressure regulation components to10QBU01072417.1Non-Provisional Patent Application 154839.000103accommodate the higher pressure characteristics of the second fuel source 110 (or low-pressure or other characteristic as the case may be). The main supply line 114 is coupled to the engine 104 and serves as a common delivery conduit that supplies fuel to the engine 104 at a desired supply pressure regardless of which fuel source is active. The desired supply pressure is less than the first pressure of the first fuel source 108 and the second pressure of the second fuel source 110, so that fuel can be delivered to the engine 104 within the acceptable operating pressure range for proper combustion. For example, the supply pressure can be about 0.5 psi, or another pressure appropriate for the specific engine or consumer requirements, such as between about 0.25 psi and about 2 psi depending on the application. In some examples, the supply pressure can be less than about 1 psi.

[0048] To control pressure of a fuel that is supplied to a consumer, a set of regulators can be coupled between a fuel source (e.g., to be between or along a fuel supply line or path) and a consumer (e.g., a main supply coupled to a consumer). Pressure regulators function by restricting fuel flow through an orifice or valve mechanism that responds to downstream pressure conditions, thereby maintaining a consistent outlet pressure regardless of variations in inlet pressure or flow demand. In the illustrated example, a first set of regulators 120 is coupled between the first supply line 112 and the main supply line 114. The first set of regulators 120 includes a first regulator 122 that is configured to reduce fuel pressure from the first fuel source 108 from the first pressure to the supply pressure. Because the first fuel source 108 operates at a relatively low first pressure (e.g., less than about 5 psi in the case of municipal natural gas mains), a single regulator stage may be sufficient to achieve the desired pressure reduction to the supply pressure. So, in the first mode or the third mode, fuel flows along a first fuel path from the first supply line 112 and through the first set of regulators 120 to the main supply line 114. The first regulator 122 can be configured as a spring-loaded diaphragm regulator, a pilot-operated regulator, or another type of pressurereducing device suitable for the specific pressure differential and flow rate requirements of the application.

[0049] In some examples, the first set of regulators 120 can include additional regulators arranged in series or in parallel with the first regulator 122 to provide the desired output pressure or flow rate. Additional regulators in series can provide staged pressure reduction when the pressure differential between the first pressure and the supply pressure warrants multiple reduction stages, while additional regulators in parallel can increase the overall flow capacity of the first11QBU01072417.1Non-Provisional Patent Application 154839.000103supply line 112 to meet higher fuel demand requirements. For example, in some configurations, the first set of regulators 120 can include two or more regulators arranged in series along the first supply line 112 to provide staged pressure reduction from the first fuel source 108. Such multistage configurations for the first supply line 112 can be advantageous when the first pressure is higher than typical municipal natural gas pressures, such as when the first fuel source 108 is an intermediate-pressure industrial gas supply, a medium-pressure propane system, or another fuel source operating at pressures that warrant multiple reduction stages. In some examples, the first set of regulators 120 can include a second regulator to reduce the first pressure to an intermediate pressure, followed by the first regulator 122 to reduce the intermediate pressure to the supply pressure. In other examples, the first set of regulators 120 can include three or more regulators in series when the pressure differential between the first pressure and the supply pressure is particularly large. The specific number and configuration of regulators in the first set of regulators 120 can be selected based on the pressure characteristics of the first fuel source 108, the desired supply pressure, the flow rate requirements, and other application-specific factors.

[0050] Correspondingly, a second set of regulators 124 is coupled between the second supply line 116 and the main supply line 114. The second set of regulators 124 includes a second regulator 126 and a third regulator 128 that is positioned between the second regulator 126 and the main supply line 114. The inclusion of multiple regulators arranged in series can more effectively regulate pressure when the pressure differential between source pressure (e.g., the first pressure or second pressure) and the desired supply pressure is above a maximum threshold differential. Single-stage pressure reduction across very large pressure differentials can result in excessive gas expansion, temperature drops that may cause regulator freezing, reduced accuracy in pressure control, and potential damage to regulator components. By distributing the pressure reduction across multiple stages, each regulator operates within a more manageable pressure differential range, improving overall system reliability and precision. Here, the second regulator 126 is configured to reduce fuel from the second fuel source 110 from the second pressure to a third pressure. For example, the second regulator 126 can reduce the fuel from the second pressure (e.g., about 3600 psi in the case of compressed natural gas) to a third pressure of less than about 85 psi (e.g., between about 50 psi to about 70 psi, or another range of pressures depending on the specific application requirements and regulator capabilities). The third pressure is preferably greater than12QBU01072417.1Non-Provisional Patent Application 154839.000103the desired supply pressure to maintain fuel flow in the desired direction to the engine 104 and to provide sufficient pressure differential for the downstream regulator to function properly. The third regulator 128 then reduces the fuel pressure from the third pressure to the desired supply pressure, completing the staged pressure reduction process. So, in the second mode or the third mode, fuel flows along a second fuel path from the second supply line 116 and through the second set of regulators 124 to the main supply line 114. In some examples, the third pressure can be selected to be approximately equal to the first pressure, which can simplify system design by allowing the third regulator 128 to operate under similar conditions as the first regulator 122. In some examples, the third pressure can be equal to the first pressure.

[0051] In some examples, the second set of regulators 124 can include additional regulators arranged in series or in parallel with the second regulator 126 and the third regulator 128 to provide the desired output pressure or flow rate. Additional regulators in series can provide staged pressure reduction when the pressure differential between the second pressure and the supply pressure warrants additional reduction stages beyond the two-stage configuration described above, while additional regulators in parallel can increase the overall flow capacity of the second supply line 116 to meet higher fuel demand requirements. For example, in applications where the second fuel source 110 operates at very high pressures (e.g., greater than about 5000 psi), the second set of regulators 124 can include three or more regulators arranged in series to distribute the pressure reduction across multiple stages. As such, a first-stage regulator can reduce the pressure from the second pressure to a first intermediate pressure, a second-stage regulator can reduce the pressure from the first intermediate pressure to a second intermediate pressure, and a third-stage regulator can reduce the pressure from the second intermediate pressure to the supply pressure. The specific number of regulators in the second set of regulators 124 can be selected based on the pressure characteristics of the second fuel source 110, the capabilities of available regulator components, and the desired precision of pressure control. Correspondingly, in some configurations, the second set of regulators 124 can include a single regulator rather than a multi-stage configuration.

[0052] In other examples, sets of regulators can be configured differently to accommodate various system architectures and operational requirements. For example, the second regulator 126 can reduce fuel from the second pressure to the first pressure, thereby bringing the high-pressure fuel from the second fuel source 110 to a pressure level equivalent to that of the low-pressure fuel13QBU01072417.1Non-Provisional Patent Application 154839.000103from the first fuel source 108. In this configuration, the first regulator 122 can be used as the third regulator 128 so that fuel is supplied to the engine 104 at the supply pressure, which can reduce component count and simplify the overall valve system design. Such a shared regulator arrangement can be advantageous in applications where space constraints, cost considerations, or maintenance simplification are priorities. In such cases, flow control elements (e.g., check valves, other types of one-way valves, or directional control valves) can be positioned at appropriate locations within the valve system to prevent unwanted backflow between the fuel sources. Backflow prevention can be particularly important when operating in the third mode where both fuel sources are simultaneously coupled to the main supply line 114, or when transitioning between operating modes, as pressure differentials between the supply lines could otherwise cause fuel to flow in unintended directions. Additionally, in configurations where regulators are shared between fuel paths, isolation valves or check valves can help prevent fuel from one source from inadvertently entering the supply line of another source when that source is intended to be blocked.

[0053] As mentioned above, control systems can be used to manage fuel flow through a valve system, including for fuel shutoff or switching operating modes. Control systems can range from manual configurations to automated systems, depending on the operational requirements, safety considerations, and level of operator involvement desired for a particular application. In the illustrated example, the valve system 102 includes a set of manual shutoff valves to allow an operator to manually control an operating mode. The valve system 102 includes a first shutoff valve 132 positioned along the first flow path between the first set of regulators 120 and the main supply line 114, and a second shutoff valve 134 positioned along the second flow path between the second set of regulators 124 and the main supply line 114. In some examples, the first shutoff valve 132 and the second shutoff valve 134 can be manual shutoff valves. The positioning of the shutoff valves downstream of the respective regulator sets can help to reduce fuel pressure to appropriate levels before reaching the shutoff valves, which can simplify valve selection and reduce component stress.

[0054] In the first mode, the first shutoff valve 132 is opened to couple the first fuel source 108 to the engine 104 and the second shutoff valve 134 is closed to block the second fuel source 110 from the engine 104, thereby directing fuel from the low-pressure first fuel source 108 through the first supply line 112 to the main supply line 114. Opening the first shutoff valve 132 couples the14QBU01072417.1Non-Provisional Patent Application 154839.000103first supply line 112 to the main supply line 114, and closing the second shutoff valve 134 decouples the second supply line 116 from the main supply line 114. In the second mode, the first shutoff valve 132 is closed to block the first fuel source 108 from the engine 104 and the second shutoff valve 134 is open to couple the second fuel source 110 to the engine 104, thereby directing fuel from the high-pressure second fuel source 110 through the second supply line 116 to the main supply line 114. Opening the second shutoff valve 134 couples the second supply line 116 to the main supply line 114, and closing the first shutoff valve 132 decouples the first supply line 112 from the main supply line 114. In the third mode, the first shutoff valve 132 and the second shutoff valve 134 are both open to couple the first fuel source 108 and the second fuel source 110 simultaneously to the engine 104, which can be useful when fuel demand exceeds the capacity of a single source or during transitional periods between operating modes. In the fourth mode, the first shutoff valve 132 and the second shutoff valve 134 are both closed to block the first fuel source 108 and the second fuel source 110 from the engine 104, isolating the engine 104 from all fuel sources, such as for maintenance, storage, or emergency shutdown purposes.

[0055] In the illustrated example, the first shutoff valve 132 and the second shutoff valve 134 are positioned to isolate the first set of regulators 120 and the first fuel source 108 from the second set of regulators 124 and the second fuel source 110. This arrangement can help prevent pressure differentials between the supply lines from causing unintended fuel migration when one source is blocked. The isolation provided by the shutoff valves also facilitates maintenance operations, as individual supply lines and their associated regulators can be serviced without affecting the other fuel path. In other examples, alternative shutoff valve arrangements can be employed to accommodate different system architectures, operational requirements, or safety standards. For example, a two-way shutoff valve (e.g., a three-port valve with a common outlet) can be used to switch operating modes, providing a single point of control that simultaneously opens one fuel path while closing the other, which can reduce the number of valve operations required to change modes and minimize the risk of operator error.

[0056] In some configurations, shutoff valves can be positioned upstream of the regulators, between a fuel source and its corresponding set of regulators, which can provide additional protection for the regulators by allowing complete isolation of the regulator components from pressurized fuel during maintenance or when a particular fuel source is not in use. Upstream15QBU01072417.1Non-Provisional Patent Application 154839.000103shutoff valve placement can also be beneficial to be cut off before the fuel reaches any pressurereducing components. In further examples, multiple shutoff valves can be arranged in series along a single fuel path to provide redundant isolation capability, which can be required in applications with stringent safety requirements or where fail-safe operation is critical. Correspondingly, different numbers and arrangements of shutoff valves can be selected and configured to meet the specific operational, safety, or regulatory requirements of a particular application, and skilled artisans will appreciate that the valve system 102 can be adapted to incorporate various shutoff valve configurations without departing from the principles of the present disclosure.

[0057] In some cases, control systems for a multi-source fuel valve system can be electronically controlled, either exclusively or in conjunction with manual controls, or other types of controls. In some cases, electronically-controlled valves can include motorized valves or pneumatic valves that can be operated by a controller. For example, the valve system can be controlled via a local valve controller, or via a main controller of a larger system that incorporates the valve system. In the illustrated example, the valve system 102 can be controlled by a controller 140 of the generator 100. The controller 140 can be configured as a programmable logic controller (PLC), a microcontroller, a dedicated electronic control unit, or another type of processing device capable of executing control logic and communicating with peripheral devices. The controller 140 can include one or more processors, memory for storing control programs and operational data, and input / output interfaces for communicating with sensors, actuators, and other system components. The controller 140 can be in communication with one or more sensors that allow the controller 140 to monitor system parameters and manipulate operation of the valve system 102 based on signals received from the one or more sensors. For example, sensors can include temperature sensors, pressure sensors, mass flow sensors, flow rate sensors, etc. to monitor operation of the valve system 102. Based on signals from the sensors, the controller 140 can perform various control functions, including changing operating modes between the first mode, second mode, third mode, or fourth mode described above, activating or deactivating warning indicators to alert operators of abnormal conditions, initiating shutdown sequences or startup procedures for the engine 104, modulating fuel flow rate to match demand requirements, determining which fuel sources are available (e.g., based on pressure readings and other parameters), logging operational data for maintenance and diagnostic purposes, or taking other actions to control system operation16QBU01072417.1Non-Provisional Patent Application 154839.000103and ensure safe and efficient performance of the generator 100.

[0058] In some configurations, the control system for the valve system 102 can include wireless communication capabilities to enable remote monitoring and control of the valve system 102. For example, the controller 140 can include a wireless transceiver to communicate with a remote monitoring station, a mobile device application, or a cloud-based management platform. Remote monitoring can allow operators to view system status, receive alerts regarding abnormal conditions, and initiate mode changes or shutdown sequences without being physically present at the generator 100 location. In some examples, the valve system 102 can be integrated with building management systems (BMS) or building automation systems (BAS) to coordinate operation with other building systems such as HVAC equipment, electrical distribution systems, or emergency power systems. The valve system 102 can also be integrated with smart grid infrastructure to enable demand response capabilities, allowing the generator 100 to adjust its operation based on grid conditions, electricity pricing signals, or utility commands. In further examples, the controller 140 can implement predictive control algorithms that consider factors such as fuel pricing forecasts, anticipated demand patterns, weather conditions, or maintenance schedules to optimize fuel source selection and system operation. The controller 140 can also be configured to automatically switch between fuel sources based on economic factors, such as transitioning from a higher-cost fuel source to a lower-cost fuel source when pricing conditions change.

[0059] Still referring to FIGS. 1-5, the controller 140 is in communication with a pressure sensor 144 (e.g., a first pressure sensor) that is configured to sense the second pressure in the second supply line 116. The pressure sensor 144 can be positioned upstream of the second regulator 126 to measure the inlet pressure from the second fuel source 110, thereby providing an indication of the remaining fuel quantity in tank-based storage systems. Based on the sensed pressure, the controller 140 can determine whether the second fuel source 110 is connected to the generator 100 or whether sufficient fuel remains in the second fuel source 110 to continue operation. In the case of tank storage configurations, such as tube trailers, ground-mounted storage tanks, mobile cylinder banks, or other pressurized vessel arrangements, the second pressure may progressively decrease as fuel is evacuated from the second fuel source 110 during generator operation. The rate of pressure decrease depends on factors such as the initial fill pressure, the tank volume, the fuel consumption rate of the engine 104, and the ambient temperature conditions. However, if pressure17QBU01072417.1Non-Provisional Patent Application 154839.000103in the tank drops below a heel pressure of the tank (e g., a minimum operating pressure for the storage vessel), the tank could become damaged. To help prevent tank damage and promote safe operation, the controller 140 can be configured to block fuel flow from the second fuel source 110 if the second pressure sensed by the pressure sensor 144 is at or below a minimum threshold pressure. The minimum threshold pressure can be set to correspond to the tank heel pressure, or can be set at a higher value to account for pressure drops that occur within the valve system 102 between the pressure sensor 144 and the tank connection point. In some cases, blocking the second fuel source 110 can include initiating a shutdown sequence for the engine 104. For example, the controller 140 can shut off the engine 104 when the second pressure reaches the minimum threshold pressure. In other cases, blocking the second fuel source 110 can include operating a shutoff valve, such as the second shutoff valve 134, to isolate the second supply line 116 from the main supply line 114 while maintaining the engine 104 in a ready state for operation on an alternative fuel source. In further cases, blocking the second fuel source 110 can include closing a regulator by actuating a solenoid or other electronically-controlled mechanism on a pressure regulator, such as the second regulator 126, to prevent fuel flow through the second supply line 116. Additionally, in configurations where the first fuel source 108 is available and operational, blocking the second fuel source 110 can include automatically switching the engine 104 to operate on the first fuel source 108 by transitioning the valve system 102 from the second mode to the first mode, thereby maintaining continuous power generation without operator intervention.

[0060] In some cases, a controller can also adjust a regulator to maintain a desired outlet pressure. For example, the first set of regulators 120 or the second set of regulators 124 can be configured with a solenoid operated actuator that enables electronic control of the regulator position and corresponding fuel flow characteristics. The controller 140 can receive pressure readings from one or more sensors positioned throughout the valve system 102 and operate the solenoid to modulate the downstream pressure relative to the regulator. The controller 140 can operate the solenoid to shut off fuel flow via the regulator, which can serve as an emergency backup isolation mechanism in the event of a system malfunction or abnormal operating condition. Correspondingly, other sensors can be used (additionally or alternatively) to monitor pressure at various points throughout the valve system 102, allowing comprehensive system monitoring and pressure control. For example, a second pressure sensor 146 is configured to sense the first pressure in the first supply18QBU01072417.1Non-Provisional Patent Application 154839.000103line 112. The second pressure sensor 146 can be positioned upstream of the first regulator 122 to measure the inlet pressure from the first fuel source 108. A third pressure sensor 148 can monitor pressure between the first regulator 122 and the first shutoff valve 132 (e.g., to verify proper operation of the first regulator 122). A fourth pressure sensor 152 can monitor the supply pressure in the main supply line 114 (e.g., to confirm that fuel is being delivered to the engine 104 at the appropriate pressure). A fifth pressure sensor 154 can monitor the third pressure between the second regulator 126 and the third regulator 128 (e.g., to verify proper staged pressure reduction). A sixth pressure sensor 156 can monitor pressure between the third regulator 128 and the second shutoff valve 134 (e.g., to confirm proper operation of the third regulator 128 before fuel enters the main supply line 114). In some examples, the valve system 102 can include a flow rate sensor 158 configured to sense a flow rate in the main supply line 114 (e.g., to confirm that fuel is being delivered to the engine 104 at an appropriate flow rate). The flow rate sensor 158 can measure the flow rate as mass per unit time, volume per unit time, or using other known techniques for determining flow. In some examples, the flow rate sensor 158 can be in communication with the controller 140 to allow for automated and / or remote monitoring of fuel delivery conditions, and in other examples, the flow rate sensor 158 can be configured for manual observation.

[0061] During valve operation, the drop in pressure of the fuel passing through the regulator can cause the regulator and other valve components to reduce in temperature. Depending on the magnitude of the pressure drop and corresponding expansion of the fuel gas, the temperature can reduce so much that it can cause freezing or other malfunctions of the valve. To prevent freezing, a valve system can include a heater that can supply heat to valve system. As shown in FIGS. 1-4, the valve system 102 can include a heater 160 to prevent freezing or temperature-related malfunctions of valve components. In the illustrated example, the heater 160 is configured as a heat exchanger 162 that transfers thermal energy to the second regulator 126, though in other examples the heater 160 can supply heat to other regulators or valve components that experience significant temperature drops during pressure reduction. The controller 140 can monitor system temperature via a temperature sensor 168 and operate the heater 160 based on signals from the temperature sensor 168 to maintain a desired operating temperature within the valve system 102.

[0062] In some configurations, the second regulator 126 can be positioned within a heater housing 164 (e.g., a housing) that retains the heater 160. The heater housing 164 provides thermal19QBU01072417.1Non-Provisional Patent Application 154839.000103insulation to improve heat transfer efficiency. For example, the heater housing 164 can help to insulate the heat exchanger 162 and the second regulator 126 from ambient temperature conditions, thereby reducing heat loss to the surrounding environment and improving the effectiveness of the heating system. The heat exchanger 162 can transfer heat (e.g., waste heat) generated by the engine 104 (or another heat generating component such as a power conversion module) to the second regulator 126, thereby utilizing thermal energy that would otherwise be dissipated to the environment. More specifically, a set of coolant lines 166 can be fluidly coupled between the engine 104 and the heat exchanger 162 to circulate engine coolant and allow heat from the engine 104 to be applied to the second regulator 126. During operation, coolant from the engine 104 absorbs heat as it circulates through the engine cooling system. The heated coolant flows along the coolant lines 166 to the heat exchanger 162. At the heat exchanger 162, the absorbed heat is dissipated to the second regulator 126, increasing or maintaining the temperature of the second regulator 126 (or another regulator as the case may be). The coolant then returns to the engine 104 to repeat the cycle.

[0063] In some examples, the coolant lines 166 can transfer heat to other components of the valve system 102, such as the first supply line 112, the second supply line 116, or other supply lines that may experience temperature drops during fuel flow. In some cases, the flow of coolant through the coolant lines 166 can be controlled by the controller 140 to modulate the temperature of the second regulator 126 or other valve components. The controller 140 can also control coolant flow to prevent heating of the regulator at startup, allowing the engine 104 time to attain a desired operating temperature before diverting heated coolant to the valve system 102. In some cases, the coolant flow can be regulated by a thermostat of the engine 104, which can automatically modulate coolant circulation based on engine temperature conditions.

[0064] In other examples, the heater 160 can be configured as or include another type of heating system suitable for the particular application requirements. For instance, the heater 160 can be a resistive heating element that converts electrical energy to heat energy through resistive losses in a conductive material. In such configurations, some of the electricity produced by the generator 100 can be directed to operate the resistive heating element, providing a self-contained heating solution that does not require external power sources. Alternatively, electricity provided to the resistive heating element can be supplied from an auxiliary power source, such as a solar panel,20QBU01072417.1Non-Provisional Patent Application 154839.000103wind turbine, auxiliary battery, grid connection, or other power supply, which can be advantageous during startup conditions before the generator 100 is producing power or in applications where diverting generator output to heating is undesirable.

[0065] During operation, expansion of the fuel within a valve system can sometimes produce condensation as the fuel gas undergoes pressure reduction and corresponding temperature drops. To remove the condensation from the fuel, as can improve system performance, the valve system 102 can include a set of condensate traps 170 (see FIGS. 3-5) that collect condensation produced within the valve system, such as at the regulators or other locations where significant pressure reduction occurs. The condensate traps 170 can be positioned at low points within the valve system 102 to facilitate gravity-driven collection of liquid condensate, and can include drain ports or valves to allow periodic removal of accumulated condensation during maintenance operations.

[0066] In some cases, components of a valve system can be supported on a base frame to provide structural organization, facilitate ease of access to individual components for maintenance or inspection, and allow for the valve system to be transported or repositioned to different locations as a single integrated unit. The frame can be configured as a welded steel structure, a modular assembly, or another type of support structure suitable for the weight and arrangement of the valve system components. For example, as shown in FIGS. 3 and 4, the valve system 102 includes a frame 174 that supports the first set of regulators 120, the second set of regulators 124, the pressure sensor 144, and the heater 160. The frame 174 can also support associated piping, fittings, and mounting hardware that interconnect the various valve system components. In other examples, the frame 174 can support additional valve components, such as a controller, shutoff valves, additional sensors, condensate traps, or other elements of the valve system 102 depending on the specific configuration and application requirements.

[0067] It is appreciated that some components of a valve system can be optional, and that components can be arranged in various configurations to meet the needs of a particular application. For example, a heater can be omitted from a valve system in applications where temperature-related issues are not expected to occur. In such cases, the valve system may not reduce a fuel pressure to a level at which freezing of the fuel gas or associated components is likely. Accordingly, the valve system may not require a heater and can reduce overall size and complexity by eliminating the heater and associated components, such as a heater housing, coolant lines, etc.21QBU01072417.1Non-Provisional Patent Application 154839.000103For example, referring to FIG. 5, the valve system 102 is illustrated without a heater (e.g., or another type of temperature control unit). Further, as illustrated in FIG. 5, the pressure sensor 148 (e.g., a first pressure sensor) can be positioned downstream of the first set of regulators 120. As such, the pressure sensor 148 can monitor the pressure in the first supply line 112 after the first set of regulators 120 reduce the first pressure to the supply pressure. Correspondingly, the pressure sensor 156 (e.g., a second pressure sensor) can be positioned downstream of the second set of regulators 124 so that the pressure sensor 156 can monitor the pressure in the second supply line 116 after the second set of regulators 124 reduce the second pressure to the supply pressure.

[0068] Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0069] Thus, while the invention has been described in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.

[0070] Various features and advantages of the invention are set forth in the following claims.22QBU01072417.1

Claims

Non-Provisional Patent Application 154839.000103CLAIMSWhat is claimed is:

1. A generator comprising:a housing;an engine positioned within the housing and configured to receive fuel at a supply pressure; anda fuel supply valve supported by the housing and including:a main supply line coupled to the engine,a first supply line to couple a first fuel source to the main supply line,a first pressure regulator positioned along the first supply line to reduce the first fuel source from a first pressure to the supply pressure;a second supply line to couple a second fuel source to the main supply line, a second pressure regulator positioned along the second supply line to reduce the second fuel source from a second pressure to a third pressure, the second pressure being greater than the first pressure, anda third pressure regulator position along the second supply line between the second pressure regulator and the main supply line to reduce the second fuel source from the third pressure to the supply pressure.

2. The generator of claim 1, wherein the supply pressure is less than about 1 psi.

3. The generator of claim 2, wherein the first pressure is less than about 5 psi and the second pressure is less than about 3600 psi.

4. The generator of claim 3, wherein the third pressure is less than about 85 psi.

5. The generator of claim 3, wherein the first fuel source is a municipal natural gas mains and the second fuel source is a compressed natural gas tank.23QBU01072417.1Non-Provisional Patent Application 154839.0001036. The generator of claim 1, wherein the fuel supply valve includes a heat exchanger that receives coolant from the engine to heat the second pressure regulator.

7. The generator of claim 1 , wherein a fuel supply valve further includes a first shutoff valve is positioned between the first supply line and the main supply line, and a second shutoff valve is positioned between the second supply line and the main supply line; andwherein the first shutoff valve is open and the second shutoff valve is closed in a first supply configuration, and the first shutoff valve is closed and the second shutoff valve is opened in a second supply configuration.

8. The generator of claim 7, wherein the first shutoff valve and the second shutoff valve are manual shutoff valves.

9. The generator of claim 7, further comprising a pressure sensor to measure the second pressure.

10. The generator of claim 9, further comprising an electronic controller in communication with the pressure sensor and configured to block the second supply line when the second pressure reaches a minimum threshold pressure.

11. The generator of claim 10, wherein the electronic controller shuts off the engine when the second pressure reaches the minimum threshold pressure.

12. The generator of claim 10, wherein the first shutoff valve and the second shutoff valve are electronically-controlled shutoff valves and the electronic controller transitions the fuel supply valve from the second supply configuration to the first supply configuration when the second pressure reaches the minimum threshold pressure.

13. The generator of claim 1, wherein the fuel supply valve positioned within the housing.24QBU01072417.1Non-Provisional Patent Application 154839.00010314. A fuel pressure regulator comprising:an outlet line configured to supply fuel to an engine at a supply pressure;a first fuel line configured to couple to a first fuel source having fuel at a first pressure; a first pressure regulator coupled between the first fuel line and the outlet line to reduce the fuel from the first pressure to the supply pressure;a second fuel line configured to couple to a second fuel source having fuel at a second pressure that is greater than the first pressure;a second pressure regulator coupled between the second fuel line and the outlet line to reduce the fuel from the second pressure to a third pressure that is between the second pressure and the supply pressure; anda control system to selectively operate the fuel pressure regulator in each of:a first mode, wherein fuel is supplied from the first fuel source to the outlet line and the second fuel source is blocked, anda second mode, wherein fuel is supplied from the second fuel source to the outlet line and the first fuel source is blocked.

15. The fuel pressure regulator of claim 14 further comprising a heating element to heat the second pressure regulator.

16. The fuel pressure regulator of claim 15, wherein the heating element is a heat exchanger.

17. The fuel pressure regulator of claim 14 further comprising a third pressure regulator coupled between the second pressure regulator and the outlet line to reduce the fuel from the third pressure to the supply pressure.

18. The fuel pressure regulator of claim 14, wherein the third pressure is equal to the firs pressure.25QBU01072417.1Non-Provisional Patent Application 154839.00010319. The fuel pressure regulator of claim 14, wherein, in the second mode, the control system is configured to block the second fuel source when the second pressure is below a minimum threshold pressure.

20. The fuel pressure regulator of claim 14, wherein the control system includes a first shutoff valve to selectively block the first fuel line and a second shutoff valve to selectively block the second fuel line.

21. A method of supplying fuel to an engine for a generator from multiple sources, the method comprising:in a first mode, coupling a first fuel supply line to a main supply line to supply the fuel from a first fuel source to the engine at a supply pressure, the first fuel supply line including a first pressure regulator to reduce the fuel from the first fuel source from a first pressure to the supply pressure; andin a second mode, coupling a second fuel supply line to the main supply line to supply the fuel from a second fuel source to the engine at the supply pressure, the second fuel supply line including a second pressure regulator to reduce the fuel from the second fuel source from a second pressure to a third pressure and a third regulator to reduce the fuel from the second fuel source from the third pressure to the supply pressure.

22. The method of claim 21, further comprising:in the first mode, decoupling the second fuel supply line from the main supply line; and in the second mode, decoupling the first fuel supply line from the main supply line.26QBU01072417.1

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