DESC:A FLAME ARRESTOR DEVICE

FIELD OF THE DISCLOSURE
The present disclosure generally relates to the field of fire protection, and more particularly, to a flame arrestor device to obstruct the flow of flame or hot gases in a reverse direction.
BACKGROUND
This section is intended to provide information relating to the technical field and thus, any approach or functionality described below should not be assumed to be qualified as prior art merely by its inclusion in this section.
Flame arrestors are safety devices designed to prevent the propagation of flames and limit the transmission of ignited gases to protect equipment and personnel. Flame arrestors are commonly used in industrial settings, especially in systems involving flammable gases or vapours. Generally, flame arrestors work by creating a series of narrow passages that the flame must pass through. These passages are designed to be small enough to prevent the flame from propagating through them. As the flame passes through the passages, it loses heat to the walls of the passages, which cools the flame and prevents it from igniting the gas mixture on the other side of the arrestor. The goal is to disrupt the flame front and dissipate heat to a level where ignition cannot occur on the opposite side of the arrestor.
Conventionally, there are three main types of flame arrestors, which include flame cell arrestors, screen arrestors, and deflector arrestors. The flame cell arrestors are made up of a matrix of small passages, typically made of crimped metal ribbons. Flame cell arrestors are the most common type of flame arrestor. The screen arrestors consist of a series of perforated plates or screens. Screen arrestors are less commonly used than flame cell arrestors, but they are often used in applications where a high flow rate is required. The deflector arrestors use a series of baffles to deflect the flame and prevent it from propagating through the arrestor. The deflector arrestors are typically used in applications where there is a high concentration of flammable gas.
Flame arrestor devices are crucial in preventing the spread of fires in industrial processes and are used in various industries such as oil and gas, petrochemicals, refining, and chemical processing. They play a vital role in maintaining the safety of personnel, protecting equipment, and preventing potentially catastrophic incidents.
Flame arrestor devices are used in a wide variety of applications. For example, tanks and vessels that contain flammable gases or liquids. In another example, piping systems that transport flammable gases or liquids. In another example, vents and stacks that release flammable gases. In another example, gas appliances, such as gas grills and portable generators.
However, flame arrestors have limited success for applications involving gas flow, where high-temperature gas movement from the hot side to the cold side of a pipe needs to be arrested. Conventional flame arrestors may struggle to effectively prevent flame propagation in such scenarios due to the challenging conditions posed by the high-temperature differential and the potential for rapid gas backflow.
Therefore, because of the existing limitations, there exists a need for a flame arrestor design that enhances flame-quenching capabilities and ensures reliable flame arrest performance even in demanding environments.
SUMMARY
This section is provided to introduce certain objects and aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.
It is an object of the present disclosure to provide a flame arrestor device that maximizes forward laminar flow and minimizes reverse flow by various kinds of flow obstructions and heat dissipating means.
It is another object of the present disclosure to provide a flame arrestor device that prevents flame propagation to the cold side, i.e., maximizes a backward flow resistance.
It is yet another object of the present disclosure to provide a flame arrestor device that employs a bypass mechanism that allows the flame arrestor to function without interfering with normal operation.
It is yet another object of the present disclosure to provide a flame arrestor device that optimizes flow management and enhances flame arrestment.
It is yet another object of the present disclosure to provide a flame arrestor device that performs the functions of a flame arrestor and a flow conditioner.
It is yet another object of the present disclosure to provide a flame arrestor device that utilizes the three modes of heat transfer to ensure rapid heat dissipation.
In the naturally aspirated Compressed Natural Gas (NA-CNG) engines, backfires may occur due to a sudden and uncontrolled ignition of the unburnt air-fuel mixture in the intake manifold and pipes. Conventional flame arrestors do not effectively prevent the backfires that occur in in the NA-CNG engines.
The present disclosure overcomes the above-mentioned limitations of the prior art by providing an enhanced flame arrestor that maximizes laminar flow and minimizes reverse flow. The present disclosure provides a flame arrestor in which flame-arresting / extinguishing features come into play only during the reverse flow and have no effect during normal operations (forward flow).
According to an aspect of the present disclosure, a flame arrestor device may be provided. The flame arrestor device may include an inlet conduit for receiving fluid, an outlet conduit for discharging the fluid, an outer chamber connecting the inlet conduit and the outlet conduit. The outer chamber includes one or more chambers.
The one or more chambers may include a funnel conduit connected to the inlet conduit and configured to receive the fluid from the inlet conduit, the funnel conduit extending across the one or more chambers in a first direction. The one or more chambers may include a flow regulator extending from the funnel conduit in the first direction, the flow regulator including at least one material.
The one or more chambers may include at least one first resilient element connecting the flow regulator with walls of the one or more chambers in a second direction being perpendicular to the first direction, and at least one second resilient element arranged between the flow regulator and the outlet conduit along the first direction, in which the outlet conduit includes a flow conditioner connected with the at least one second resilient element along a third direction opposite to the first direction.
In another embodiment of the present disclosure, the one or more chambers may include a first chamber connected to the inlet conduit, a second chamber and a third chamber connected to the outlet conduit in which the second chamber is arranged between the first chamber and the second chamber across the first direction.
In another embodiment of the present disclosure, the first chamber may include one or more particles. The one or more particles are a globule filled with fire-extinguishing substances.
In another embodiment of the present disclosure, the second chamber may include one or more porous substances.
In another embodiment of the present disclosure, the third chamber may include the flow regulator. The at least one first resilient element is configured to connect the flow regulator with walls of the third chamber in the second direction.
In another embodiment of the present disclosure, the funnel conduit extends across the first chamber and the second chamber in the first direction.
In another embodiment of the present disclosure, the second chamber is spaced apart from the first chamber by a perforated globule retainer.
In another embodiment of the present disclosure, the first chamber, the second chamber and the third chamber are configured to absorb and dissipate heat from entering through outlet conduit.
In another embodiment of the present disclosure, the funnel conduit including a first opening and a second opening is smaller than the first opening, and in which the first opening is configured to overlap an opening of the inlet conduit in the first direction and the second opening being configured to receive the flow regulator in the first direction.
In another embodiment of the present disclosure, the funnel conduit includes an anchoring strut arranged at the first opening in the second direction and at least one third resilient element connecting the anchoring strut to the flow regulator along the first direction.
In another embodiment of the present disclosure, the inlet conduit may include at least one inner perforated tube formed along walls of the inlet conduit. The at least one inner perforated tube may include one or more particles being a globule filled with fire-extinguishing substances. The outlet conduit may include at least one inner perforated tube formed along walls of the outlet conduit. The at least one inner perforated tube may include one or more particles being a globule filled with fire-extinguishing substances.
In another embodiment of the present disclosure, the outer chamber may include one or more joints.
In another embodiment of the present disclosure, the flow conditioner may include a matrix of passages, the passages being configured to receive the fluid from the outer chamber and dispense the fluid to the outlet conduit.
In another embodiment of the present disclosure, the at least one second resilient element is at least one of a sacrificial resilient element or a tension spring.
In another embodiment of the present disclosure, in a first state, the flow regulator may be configured to move towards the flow conditioner in the first direction while being spaced apart from the second opening of the funnel conduit by means of the at least one third resilient element and the at least one first resilient element, and wherein the first state being a state of normal flow of fluid.
In another embodiment of the present disclosure, the flow regulator may include the at least one material covered by a lid. The at least one material may include fire-extinguishing substances, in which, in a second state, the flow regulator may be configured to move towards the first opening of the funnel conduit in the third direction while being detached from the at least one second resilient element by means of the lid. The flow regulator, in the second state, is configured to release the at least one material with the second state being a state of reverse flow of fluid.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated herein, and constitute a part of this disclosure, illustrate exemplary embodiments of the disclosed methods and systems in which, like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure.
Although exemplary connections between sub-components have been shown in the accompanying drawings, it will be appreciated by those skilled in the art, that other connections may also be possible, without departing from the scope of the disclosure. All sub-components within a component may be connected to each other, unless otherwise indicated.
FIG. 1 illustrates a conventional naturally aspirated Compressed Natural Gas (NA-CNG) engine according to an embodiment of the present disclosure.
FIG. 2 illustrates a conventional NA-CNG engine according to an embodiment of the present disclosure.
FIG. 3 illustrates a conventional NA-CNG engine adapted to the proposed disclosure according to an embodiment of the present disclosure.
FIG. 4 illustrates a schematic diagram of a flame arrestor device according to an embodiment of the present disclosure.
FIG. 5 illustrates a schematic diagram of a flow conditioner of the flame arrestor device according to an embodiment of the present disclosure.
FIG. 6 illustrates a schematic of a flow regulator and a bimetallic spring of the flame arrestor device according to an embodiment of the present disclosure.
FIG. 7 illustrates a cross-sectional view of an annular thermally conductive open-cell foam of the flame arrestor device according to an embodiment of the present disclosure.
FIG. 8 illustrates a cross-sectional view of a perforated globule retainer sheet of the flame arrestor device according to an embodiment of the present disclosure.
FIG. 9 illustrates a schematic diagram of the flame arrestor device in a normal flow of the gases according to an embodiment of the present disclosure.
FIG. 10 illustrates a schematic diagram of the flame arrestor device in a reverse flow (without a tension spring) according to an embodiment of the present disclosure.
FIG. 11 illustrates a schematic diagram of the flame arrestor device in a reverse flow (with a tension spring) according to another embodiment of the present disclosure.
FIG. 12 illustrates a schematic diagram of the flame arrestor device according to yet another embodiment of the present disclosure.
FIG. 13 illustrates the schematic diagram of the flame arrestor device according to yet another embodiment of the present disclosure.
The foregoing shall be more apparent from the following more detailed description of the disclosure.
DESCRIPTION OF THE DISCLOSURE
Exemplary embodiments now will be described with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. The terminology used in the detailed description of the particular exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting. In the drawings, like numbers refer to like elements.
The specification may refer to “an”, “one” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “include”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In the following description, for the purposes of explanation, numerous specific details have been set forth in order to provide a description of the disclosure. It will be apparent, however, that the disclosure may be practiced without these specific details and features.
As is generally known, backfire, a sudden and uncontrolled ignition of the unburnt air-fuel mixture in the intake manifold and pipes, is a common occurrence in naturally aspirated CNG (NA-CNG) engines. This phenomenon, characterized by an explosive sound, poses a significant risk to the integrity of the air filter.
Figs. 1 to 2 illustrate a conventional naturally aspirated Compressed Natural Gas (NA-CNG) engine according to an embodiment of the present disclosure. As shown in Fig.1, in a conventional NA-CNG engine, air entering through the air intake snorkel 10 is filtered by the air-filter system 12 and enters the air pipe 14. The fuel from the CNG tank 22 passes through the conventional flame arrestor device 20 and enters the air pipe 14. The fuel mixes with air in the air pipe 14 and enters the air intake manifold 30. In the engine 32, air mixture is compressed, and the compressed mixture ignites via spark plug in the engine 32. During the brief moment when both intake and exhaust valves 34 of the engine 32 are open simultaneously, for example, at the end of the exhaust stroke and start of the intake stroke, the hot exhaust gases enter the intake manifold 30, triggering the ignition of the air-fuel mixture entrapped between the intake manifold 30 and the air-filter system 12. Due to the proximity of the air filter element 12 to the intake manifold, it is particularly vulnerable to damage from backfire, often melting under intense heat, as shown in Fig. 2. This event occurs without any forewarning and often goes unnoticed by the driver. The vehicle would continue to run, seemingly normally, but without any air filtration. It is only a matter of time before the unfiltered air severely damages the engine 32.
Fig. 3 illustrates a conventional NA-CNG engine adapted to the proposed disclosure according to an embodiment of the present disclosure.
The proposed disclosure provides a solution to the above problem by providing an element (as illustrated in Fig. 3) into the system so that the backfire is completely arrested at best or severely mitigated at worst, thereby saving the air-filter element and the engine 32 thereof. The disclosure may also be configured such that the air quantity is just sufficient for the vehicle to go into a limp-home mode.
While the present disclosure has been contextualised taking an NA-CNG engine as an example, its application is not limited to IC engines. For example, the present disclosure may be used to contain flames arising out of a backfire, depending upon its application.
Fig. 4 illustrates a schematic diagram of a flame arrestor device according to an embodiment of the present disclosure.
The present disclosure provides a flame arrestor device 100 that obstructs the flow of flame. The flame arrestor device includes a housing with an inlet pipe 110 to direct the flow of gases in a forward direction and an outlet pipe 130 to discharge the gases. The flame arrestor device facilitates unrestricted flow from the cold side (e.g., inlet pipe) to the hot side (e.g., outlet pipe) minimizing flow resistance and preventing flame propagation to the cold side (e.g., inlet pipe). In other words, the backward flow resistance of the flame arrestor device should be maximum.
The flame arrestor, according to an embodiment of the present disclosure, ensures that the flame-arresting/ extinguishing features only come into play during the reverse flow and have no effect during normal operation (e.g., forward flow). Such flame arrestor device minimizes operational disruptions and maximizes flame arrestment effectiveness. Unlike conventional designs where the flame arrestor device disrupts the forward flow path, the flame arrestor device according to the present disclosure employs a bypass mechanism that allows the flame arrestor device to function without interfering with normal operation. As used herein, the terms "flame arrestor" and "fire arrestor device" refer to the same thing and have been used interchangeably throughout the description.
The flame arrestor device 100 includes a housing with an inlet pipe 110 and an outlet pipe 130, and a nozzle or funnel conduit 122. Furthermore, there may be one or more components of the flame arrestor, and the same is not shown in the Fig. 4 for the sake of clarity.
As shown in Fig.4, the flame arrestor device or the flame arrestor device 100 includes an inlet conduit or inlet pipe 110 for receiving fluid. According to an embodiment, the inlet conduit 110 may be positioned at the cold side of the flame arrestor device 100. The inlet pipe 110 receives a mixture of filtered air and fuel from the fuel tank, for example, a compressed natural gas (CNG) tank.
According to an embodiment, the inlet pipe 110 includes an inner perforated tube 112 which is formed along walls of the inlet conduit 110. According to an embodiment, the cavity between the inner perforated tube 112 and the inlet fluid is filled with particles or globules 160 (as shown in Fig.4). The tiny globules 160 are filled with flame-extinguishing medium such as carbon dioxide. The globule casing is made of a non-flammable material but quickly ruptures when exposed to high temperatures, releasing the flame extinguishing material filled inside. The flame arrestor device 100, according to an embodiment of the present disclosure, provides a nozzle 122 with design that promotes forward flow while hindering reverse flow, and further enhances flame arrestment effectiveness. The proximity of the nozzle 122 also has fire-extinguishing globules 160 to prevent the flame front from traveling towards the cold side (e.g., inlet pipe) by locally extinguishing the flame.
The flame arrestor device 100 includes an outlet conduit or outlet pipe 130 for discharging the fluid. The outlet pipe 130 has a flow conditioner 128, which ensures a laminar output flow. The flame arrestor device 100 includes an outer chamber 120 connecting the inlet conduit 110 and the outlet conduit 130. The outlet conduit 130 includes at least one inner perforated tube 114 formed along walls of the outlet conduit 130. The inner perforated tube 114, including one or more particles 160 being a globule filled with fire-extinguishing substances.
The hot side of the housing is shaped to channel the forward flow into the outlet pipe 130 and diverge the reverse flow into chambers 123 and 126. The housing generally has two parts, which could be bolted together using a leak-tight flange or weld. The former is useful when there is a need to replace components within the housing.
The outer chamber 120 includes multiple chambers 123, 124, 126. According to an embodiment, the chambers 123, 124, 126 include a first chamber 123, a second chamber 124 and a third chamber 126 connected to the outlet conduit 130. The first chamber 123 connected to the inlet conduit 110.
The second chamber 124 is arranged between the first chamber 123 and the third chamber 126 across a first direction. The first chamber 123, the second chamber 124 and the third chamber 126 are configured to absorb and dissipate heat from entering through outlet conduit 130.
The first chamber 123 includes one or more particles 160. The one or more particles 160 being a globule filled with fire-extinguishing substances.
The second chamber 124 is spaced apart from the first chamber 123 by a perforated globule retainer 164.
The chambers 123, 124, 126 include a funnel conduit or nozzle 122 which extends across the chambers 123, 124, 126 in a first direction. The nozzle 122 is connected to the inlet conduit 110 and receives the air-fuel mixture from the inlet conduit 110.
The funnel conduit or nozzle 122 has a first end or first opening 132 and a second end or second opening 134. The funnel conduit 122 extends across the first chamber 123 and the second chamber 124 in the first direction. The inlet conduit terminates into a nozzle 122 designed specifically to increase the flow velocity while preventing the backflow of the fluid or the air-fuel mixture.
The inlet conduit 110 directs forward flow of fluid into the nozzle or funnel conduit 122. The first end or first opening 132 of the nozzle 122 i.e., a larger end is connected to the inlet pipe, and the second end or second opening 134 of the nozzle 122 i.e., a smaller end. The first opening 132 is configured to overlap an opening of the inlet conduit 110 in the first direction.
The third chamber 126 includes the flow regulator 127, which extends from the funnel conduit 122 in the first direction. The second opening 134 of the nozzle 122 i.e., a smaller end is connected to a flow regulator 127 during forward flow (as shown in Fig. 4).
The third chamber 126 includes first resilient elements 125 connecting the flow regulator 127 with walls of the third chambers 126 in a second direction, the second direction being perpendicular to the first direction. According to an embodiment, the first resilient element 125 is a bi-metal spring support. The bi-metal spring supports support the flow regulator 127 as shown in Fig. 6 by connecting them to the walls of the third chambers 126.
A second resilient element 129 is arranged between the flow regulator 127 and the outlet conduit 130 along the first direction. According to an embodiment, the second resilient elements 129 is a sacrificial restraint element or a tension spring.
The funnel conduit 122 includes an anchoring strut 142 arranged at the first opening 132 in the second direction and at least one third resilient element 144 connecting the anchoring strut 142 to the flow regulator 127 along the first direction.
The flow regulator 127 includes at least one material 152. According to an embodiment, the one material 152 is a fire extinguishing substance.
The outlet conduit 130 includes the flow conditioner 128 connected with the at least one second resilient element 129 along a third direction opposite to the first direction.
As illustrated, the first end 132 of the nozzle 122 has a larger cross-sectional area to allow the entrance of gases and the second end of the nozzle 122 has a smaller cross-sectional area, in comparison to the first end 132, to allow the passing of the gases to the flow regulator 127, wherein the second end 132 of the nozzle is blocked by the flow regulator 127 during the backfire event to obstruct the flow of flame. The diameter of the nozzle outlet port 134 is selected in such a manner that the flow regulator 127 can tightly plugin (similar to a cork on a bottle) into the mouth during reverse flow under hot conditions if a tension spring 144 is present. If not, the nozzle 122 is partially blocked during reverse flow under hot conditions with the gap “d” being reduced.
The outlet conduit 130 includes a flow conditioner 128. The flame arrestor device 100, according to an embodiment of the present disclosure, provides a flow regulator that ensures bi-directional flow characteristics, promoting unobstructed forward flow towards the flow conditioner 128 and directing reverse flow towards the open-cell thermally conductive foam for immediate heat dissipation. Such flow regulator 127 optimizes flow management and enhances flame arrestment. The flow regulator 127 is made out of a highly thermally conductive material and its profile incorporates a mechanism that actively mitigates reverse flow, ensuring consistent and reliable flame arrestment.
The flow regulator 127 automatically plugs the nozzle during backflow with the support of the bi-metal spring support 125 and tension spring mechanism that thereby provides an additional layer of protection. Thus, the flow regulator 127 also serves as a non-return valve during backflow.
The flame arrestor, according to an embodiment of the present disclosure, provides a flow conditioner 128 that serves a dual purpose, i.e., acts as both the flow conditioner 128 and a flame arrestor. The flow conditioner 128 optimizes space utilization and enhances overall system performance.
The flame arrestor device 100, according to an embodiment of the present disclosure, provides a laminar flow from the cold side (e.g., inlet side) to the hot side (e.g., outlet side) while transitioning to turbulent flow from the hot side to the cold side. This flow pattern enhances heat transfer and flame arrestment.
The second chamber 124 includes porous substances 162. According to an embodiment, the porous substance 162 may be an open cell thermally conductive foam to maximize heat absorption during reverse flow by utilizing all three modes of heat transfer, namely conduction, convection, and radiation. The open-cell thermally conductive foam 162 structure ensures rapid heat dissipation, effectively quenching the flame. The foam sponges the heat out. The open-cell thermally conductive foam 162 disrupts the flame front by causing it to undergo Brownian motion, effectively randomizing and weakening the flame. This disruption impedes flame propagation and enhances flame arrestment.
The flame arrestor, according to an embodiment of the present disclosure, provides the flow regulator 127, which apart from its outer shape, is also a flow regulator 174 containing a fire extinguishing medium at high pressure. In an example, during high temperatures, the pressure inside rapidly increases and ejects the lid, thereby filling the chambers 123, 124, 126 with an extinguishing medium such as carbon dioxide. Additionally, the flow regulator 127 may include flame-extinguishing globules. All these together effectively disrupt and annihilate the flame front.
The flame arrestor, according to an embodiment of the present disclosure, provides six levels of heat absorption and four levels of fire-extinguishing features in a compact package.
The flame arrestor device 100, according to an embodiment of the present disclosure, provides an assemblage of parts that could be easily replaced, thus favouring serviceability.
The flame arrestor, according to an embodiment of the present disclosure, provides different components serving multiple functions, for example, the open-cell thermally conductive foam 162 which can be readily configured into various shapes, sizes, and densities to suit specific application requirements.
The flame arrestor, according to an embodiment of the present disclosure, omits moving parts, such as valves or kinematic arrangements like swivels and hinges, thereby ensuring simplicity, reliability, and reduced maintenance requirements.
The flame arrestor, according to an embodiment of the present disclosure, facilitates low-resistance gas flow from the cold side to the hot side in the first direction, yet, in the presence of a flame originating from the hot side, it redirects the flow to prevent easy access to the cold side. Thus, the flame arrestor device 100 is configured to optimize both forward and reverse flow scenarios for enhanced safety and efficiency.
Further, the flame arrestor device may include the flow conditioner 128 made of a material with high thermal conductivity. As shown in Fig. 5, the flow conditioner 128 is illustrated as a matrix of passages 135 with a square cross-section. However, it could be of any suitable cross-sectional geometry such as a honeycomb, etc. The the passages 135 receive the fluid from the outer chamber 120 and dispense the fluid to the outlet conduit 110. The grid density of the passages 135 could depend on the type of application and the quality of output flow desired. During the forward flow i.e., flow of fluid in the first direction, the flow conditioner 128 makes the flow laminar, and during reverse flow, it offers the first level of restriction and heat absorption.
Furthermore, the flame arrestor device may include the flow regulator 127 positioned inside the housing using the support of at least one bi-metallic spring 125. The flow regulator 127 facilitates the unobstructed flow of gases along the direction of a central axis of the outlet pipe 130 and prevents the reverse flow of the flame. At least one bi-metal spring support 125, during the backfire event, bends to allow flammable gases to enter the chamber 123 for prevention of the spread of the flame, wherein bending of at least one bi-metal spring support is performed based on a bending mechanism during the backfire event. The bending mechanism enables bending of the at least one bi-metal spring support 125 based on a differential thermal expansion principle, the bending mechanism facilitates movement of the flow regulator 127 in a reverse direction for blockage of the second end of the nozzle 134 and obstruction of flow of flame.
In an implementation of the present disclosure, the flow from the nozzle, during forward flow, passes over the flow regulator 127. During the forward flow, the gases pass through the flow regulator 127 which acts as an aerodynamic forward flow stabilizer that offers the least aerodynamic resistance so that the flow proceeds along the direction of the central axis of the outlet pipe 130 i.e., along the first direction. However, during reverse flow, the gas impinges on a flow deflector, which redirects the flow towards chamber 126 of the housing, which in turn encounters the open cell thermally conductive foam 162. The flow regulator 127 is positioned inside the housing with the support of a bi-metal spring support 125. The bi-metal spring support 125 acts as a flow deflector bending to the left to plug in the nozzle preventing the inflow of the air-fuel mixture through the nozzle. . The flow regulator 127 is made of a material of high thermal conductivity, light in weight with a smooth surface finish. The flow regulator 127 and at least one first resilient element 125 or bi-metal spring support 125 together form the second and third levels of heat-absorbing devices. The second resilient element is positioned along the second direction, which is perpendicular to the first direction.
Furthermore, as illustrated in Fig. 6, at least one bi-metal support spring 125 provides support to the flow regulator 127 which can for example be in the form of strips. These strips are designed such that during forward flow the flow regulator 127 is pushed to the right with relative ease for unobstructed flow. Under normal conditions, when there is no flow, a gap is maintained between the nozzle 122 and the flow regulator 127 using a sacrificial tension restraint 129.
In accordance with an embodiment of the present disclosure, in the event of a backfire, the present invention incorporates the following mitigation features:
First, since the flow regulator is made out of thermally conductive material, it forms a second level of heat absorption device.
Second, at least one bi-metal spring support itself acts as a third level of heat absorption device.
Third, the flame burns or melts the sacrificial tension restraint 129, which makes the bi-metal spring support 125 shove the flow regulator 127 into the nozzle 122, but not completely plug the nozzle.
Fourth, the bi-metal spring support curls itself, due to differential thermal expansion, in a manner that the flow regulator is pushed to the left. This reduces the gap (shown as dimension “d” in Fig. 4) between the nozzle 122 and the flow regulator 127, partially arresting the flow. In this respect, the hot gases fill the chambers 123, 124 and 126, thereby coming in contact with the open cell thermally conductive foam 162.
Fifth, the flow regulator is filled with a flame-extinguishing medium (such as carbon dioxide), under high pressure. Because of the heat, the pressure inside the flow regulator 127 increases, and the lid pops out, releasing the extinguishing medium into chambers 123, 124 and 126.
Furthermore, the flame arrestor device may include an annular foam. In an example, as shown in Fig. 7, the annular foam may be an open-cell foam of a circular cross-section with a hole in the middle. The open-cell foam 162 is made of a material with high thermal conductivity and serves as a principal heat-absorbing device, which provides a maximum level of heat absorption. The density of the foam is suitably designed to balance the amount of heat that could be absorbed, without unduly restricting the flow. In case the foam is designed to be sacrificial, the joint 150 in Fig. 4 could be made removable for easy replacement of the foam or any other members.
Furthermore, the flame arrestor device 100 may include chambers 123, 124 and 126 which form a part of the arrestor that remains passive during forward flow and participates in absorbing heat during reverse flow as another heat absorbent. Still further, chamber 123 has fire-extinguishing globules with an outer casing made of a material that easily ruptures under high temperatures and allows the fire-extinguishing medium (such as carbon dioxide) to be released into the chamber 123, 124 and 126.
Furthermore, the flame arrestor device 100 may include a sacrificial tension restraint 129 to hold the flow regulator in place against the resistance of the bi-metal spring support 125. The sacrificial tension restraint 129 melts, snaps or severs during a backfire event allowing the flow regulator 127 to move in the third direction, and seal the nozzle, preventing the flame from propagating in the reverse direction.
In an example, the sacrificial tension restraint 129, under normal conditions, pulls the flow regulator and fastens it to the outlet pipe. When there is a backfire and consequent temperature rise, the sacrificial tension restraint 129 either melts, snaps, or chars, thereby relieving/releasing the tension. The bi-metal spring support 125 snaps back and lodges the flow regulator 127 into the nozzle’s mouth 122 reducing the gap between the nozzle 122 and the flow regulator 127.
According to an embodiment of the present disclosure, when a tension spring 144 is included, the flow regulator completely plugs the nozzle, acting as a non-return valve.
Furthermore, the outer chamber 120 includes housing joints 150 which is made for easy serviceability such that all the internal components can be repaired or replaced if required. The flame arrestor device also includes a perforated inner tube 122 cavity at the upper and lower end of the inlet pipe and in the vicinity of the nozzle, wherein the perforated inner tube cavity is filled with a set of fire-extinguishing globules to release fire extinguishing medium for prevention of the spread of fire during the backfire event. In an example, the fire-extinguishing globules are tiny globules filled with flame-extinguishing medium such as carbon dioxide. The globule casing is not flammable but instantly ruptures at high temperatures releasing the flame extinguisher filled inside.
Furthermore, the flame arrestor device100 may include a perforated globule retainer 164. The second chamber is spaced apart from the first chamber 123 by a perforated globule retainer 164.
As shown in Fig. 8, the perforated globule retainer sheet is a perforated thin sheet made of a highly conductive material that holds all the fire-extinguishing globules within the housing chamber. This forms one of the levels of the heat absorption mechanism. For example, there are six levels of heat absorption mechanisms and a distinct difference in paths between forward and reverse flows. In addition, the flow regulator 127 pops open and disgorges the flame-extinguishing medium inside the third chamber 126.
Furthermore, the flame arrestor device 100 may include a tension spring 144. This optional spring, also known as a mouse trap spring, instantly makes the flow regulator 127 plug the nozzle 122 mouth in the event the sacrificial tension restraint 129 snaps. One end of the spring 144 is fastened to the flow regulator 127 and the other end is fastened to a tension spring anchoring strut142.
Fig. 9 illustrates a schematic diagram of the flame arrestor device 100 in a normal flow of the gases or the first state according to an embodiment of the present disclosure. During regular forward flow of the air-fuel mixture, from left to right in the first direction, the fluid enters the flame arrestor device 100 through the inlet conduit 110 and passes through the first opening 132 of the nozzle 122, which has a larger cross-sectional area. The air-fuel mixture is discharged through the second opening 134 of the nozzle 122 which has a smaller cross-sectional area. As the air-fuel mixture passes through the nozzle, the pressure of the air-fuel mixture gradually increases as it reaches the second opening 134. This increase in pressure is attributed to the design of the nozzle.
The increased fluid pressure facilitates the movement of the flow regulator 127 to the right in the first direction, thereby enlarging the gap between the flow regulator 127 and the nozzle 122, resulting in increased spacing. The expanded space allows for a greater flow of the fluid. The flow regulator 127 is held in position by means of the at least one first resilient element 125 and the tension spring 144. The first resilient element 125 is positioned in a second direction which is perpendicular to the first direction. During normal flow, the first resilient element or the bi-metal spring support 125 is pushed to the right in the first direction, with the increased pressure further facilitating the expansion of the bi-metal spring support 125 in the first direction. This expansion further increases the space for fluid flow, allowing more fluid to enter and resulting in a rise in pressure along the first direction. The expansion of the bi-metal spring support 125 pushes the second resilient element or the sacrificial tension restraint 129 to the right causing the sacrificial tension restraint 129 to lose /release its tension.
The fluid flows through the flow conditioner 128 and is discharged by the outlet conduit 130 as a laminar output flow. The flow of fluid during normal operation occurs with minimal restriction due to the combination of unique design of the nozzle, movement of the bi-metal spring support 125 in the first direction and creation of increased space for the fluid flow. Thus, the flame arrestor device 100 provides an unobstructed pathway for forward flow of the air-fuel mixture. The first chamber 123 and third chamber 126 do not participate in the flow during normal operation of the flame arrestor device 100.
Reverse flow occurs due to backfire when the hot gases gush from right to left i.e. in the third direction. Fig. 10 illustrates a schematic diagram of the flame arrestor device 100 in a reverse flow or second state (without a tension spring) according to an embodiment of the present disclosure. Hot gases enter through the outlet conduit 130. The outlet conduit 130 includes an inner perforated tube 114 with globules. The outer casing of the globules is made of a material that easily ruptures under high temperatures, allowing the fire-extinguishing medium (such as carbon dioxide) contained within to escape into the chamber. The hot gases increase the pressure of the flame extinguishing medium and causes the globules in the inner perforated tube 114 to rupture and disgorge flame-extinguishing medium to douse the flame.
The second resilient element or the sacrificial tension restraint 129 melts and snaps due to the excessive heat of the hot gases releasing the bi-metal spring support 125. The bi-metal spring support 125 moves from right to the left in the third direction. The bi-metal spring support curls itself, due to differential thermal expansion, in a manner that the flow regulator 127 is pushed to the left. The pressure of fluids flowing from the outlet conduit 130 in the reverse direction facilitates the movement of the bi-metal spring support 125 to move in the third direction.
This movement of the bi-metal spring support in the third direction pushes the flow regulator 127 towards the first opening 132 of the funnel conduit 122, which is further facilitated by the pressure of fluids in reverse direction. The movement of the flow regulator 127 towards the first opening 132 reduces the gap of the second opening 134. The second opening 134 is configured to receive the flow regulator 127. The flow regulator 127 partially plugs the mouth of the nozzle 122 stopping the flow of the air-fuel mixture. The reduced space of the second opening 134 restricts the flow of fluid or the air fuel mixture into the third chamber 126 partially reducing the supply of fuel for flame to progress.
The flow regulator 127contains a flame-extinguishing medium (such as carbon dioxide) at high pressure. Because of the heat, the pressure inside the flow regulator 127 further increases, and the lid 170 pops out, releasing the extinguishing medium into the chambers 123, 124 and 126.
The flow regulator 127 forms a second level of heat absorption device. The bi-metal spring support 125 itself acts as a third level of heat absorption device. The bi-metal spring support 125 acts a deflector redirecting the flame path towards the chambers 123, 124 and 126. As the hot gases progress to fill the chambers 123, 124 and 126, they come in contact with the open cell thermally conductive foam 162. The open cell thermally conductive foam 162 partially absorbs the heat. The open cells of the foam 162 allow the heat to pass to the first chamber 123. The globules in the first chamber 123 rupture and release the fire extinguishing medium restricting the flow of hot gases. In the event that hot gases enter the inlet conduit 110 through different modes of heat transfer, the globules in the inner perforated tube 112 of the inlet conduit 110 rupture releasing the flame extinguishing medium.
In the unrestrained position of the bimetal spring support 125(as shown in Fig.10), the flow regulator partially plugs the mouth of the nozzle 122 leaving a small gap between itself and the nozzle.
Fig. 11 illustrates a schematic diagram of the flame arrestor device 100 in a reverse flow (with a tension spring) according to another embodiment of the present disclosure. The flow regulator 127 is connected to the anchoring strut 142 by at least one third resilient element or tension spring 144.
During reverse flow of gases, the second resilient element or sacrificial tension restraint 129 melts, releasing hold of the bi metal spring support 125. The tension spring 144 relaxes pulling the flow regulator 125 to the left. The flow regulator 125 fits precisely into the second opening 134 of the nozzle 122.
The flow regulator 127 completely plugs the nozzle, acting as a non-return valve, that completely blocks any backflow. This prevents the flow of air-fuel mixture into the third chamber 126. The pressure of the flame extinguishing medium in flow regulator 127 increases due to the heat of the gases received from the outlet conduit 130. The flow regulator 127 pops out releasing the lid 170 due to the pressure of the flame extinguishing medium contained in the flow regulator 174. The lid 170 is fastened to the outlet pipe 130 by the sacrificial tension restraint 129, a resilient member that pulls the lid to the right along the first direction facilitating the release of the flame extinguishing medium.
According to an embodiment, the flame arrestor device may not include a first resilient element 125. Fig. 12 illustrates a schematic diagram of the flame arrestor device 100 according to another embodiment of the present disclosure. According to an embodiment, the flow regulator 127 is supported by the one or more tension springs 144. The flow regulator is not supported by a bi-metallic spring support 125. During reverse flow of gases, the lid 170 of the flow regulator 127 opens due to the pressure of the flame extinguishing medium contained in the flow regulator 174. The lid 170 and the flow regulator 174 move apart to the right and left respectively, due to the resilience of the tension springs 144 facilitating the release of the flame extinguishing medium.
Fig. 13 illustrates the schematic diagram of the flame arrestor device according to another embodiment of the present disclosure. The flow regulator 174 seals the second opening 134 of the nozzle 122, blocking the air-fuel mixture from entering the third chamber 126 and effectively cutting off the fuel supply to the flame. The lid 170 blocks the outlet conduit 130 preventing further flow of hot gases from the outlet conduit 130.
In general, the reverse flow of flame occurs due to backfire when the hot gases gush from right to left i.e., in a reverse direction. On the occurrence of the reverse flow, the following flow steps occur in the flame arrestor device 100:
First, the globules on the outlet pipe rupture and disgorge fire-extinguishing medium – the first level of flame extinguishment.
Second, the flow conditioner 128 becomes the first device to absorb heat – the first level of heat absorption.
Third, the flow regulator 127 gets heated up – the second level of heat absorption.
Fourth, the bi-metal spring support 125 also absorbs heat – the third level of heat absorption.
Fifth, when the heat becomes sufficiently high, the sacrificial tension restraint 129 snaps by either melting or burning:
(i) Without tension spring 144: relieving the bi-metal spring support, thus forcing the flow regulator 127 to reduce the gap between it and the mouth of the nozzle 122. The propensity of the flow regulator 127 to go closer to the nozzle 122 is additionally assisted by the hot bimetallic spring 125 which deflects in a manner favouring the same, as shown in Fig. 10.
(ii) With the tension spring 144: The tension spring pulls the flow regulator and closes the nozzle 122 instantly, in addition to the above, as shown in Fig. 11 – for the prevention of flame propagation.
Sixth, the internal pressure in the flow regulator 127 increases due to the high temperature, and the high-pressure flame extinguishing medium within gets disgorged into the chamber 126 – the second level of flame extinguishment.
Seventh, the open cell thermally conductive foam 162 absorbs the bulk of the heat as the fourth heat-absorbing device.
Eighth, the highly thermally conductive perforated globule retainer sheet (O) absorbs heat – the fifth heat-absorbing device.
Ninth, the housing itself being thermally conductive becomes the sixth heat-absorbing device.
Tenth, the fire-extinguishing globules (M) in the inlet pipe (B) also rupture, offering a wall of fire-extinguishing medium in the vicinity of the nozzle – the third level of flame extinguishment.
Eleventh, chambers (I and J) constitute a plenum and are filled with flame-extinguishing products due to the contents of the flow regulator and the globules. These arrest the flame from moving into the left, which is also assisted by the flow regulator 127 which physically plugs the nozzle 122 mouth i.e. the second opening 134 of the nozzle 122. Since the pressure inside the plenum is high, the joint 150 between the nozzle 122 and the flow regulator 127 is tight.
Thus, according to the present disclosure, there could be the following embodiments in such situations of reverse flow.
According to a first embodiment of the present disclosure, in the exemplary NA CNG engine, while the backfire should be arrested, there must be some opening for the inlet air to flow so that the vehicle can still operate in a limp-home mode to the nearest point of repair or shelter. This condition is shown in Fig. 10. A minimum gap is always maintained between the flow regulator 127 and the nozzle 122 so that the airflow is not completely choked.
According to a second embodiment of the present disclosure, in conditions where the backflow must be entirely arrested, an arrangement as shown in Fig. 11 is proposed. The tension spring 144 forces the leading end of the flow regulator 174 or the flow regulator 127 to plug the nozzle 122 completely, thereby protecting the inlet side from the approaching flame front.
According to a third embodiment of the present disclosure, during the reverse flow of flame, there could be a particularly severe condition where there is a need to completely isolate both the inlet and the outlet sides. In this regard, the plenum becomes a buffer separating the inlet 110 and the outlet 130. In this embodiment, two tension springs 129 could be utilised, as shown in Error! Reference source not found. 12.
In an example, in the flame arrestor, the bi-metal spring support may or may not be present, although in the illustration below, for the sake of clarity, the bi-metal spring support 125 has not been shown. The flow regulator 174 is suitably modified so that during extreme heat it ruptures into two parts with each part respectively plugging the inlet and outlet, as shown in Fig. 13.
The present disclosure provides a flame arrestor device that obstructs the flow of flame. The flame arrestor device facilitates unrestricted flow from the cold side (e.g., inlet pipe) to the hot side (e.g., outlet pipe) minimizing flow resistance and preventing flame propagation to the cold side (e.g., inlet pipe). In other words, the backward flow resistance of the flame arrestor device should be maximum.
While the present disclosure has been described with reference to certain preferred embodiments and examples thereof, other embodiments, equivalents, and modifications are possible and are also encompassed by the scope of the present disclosure.

Dated this 21st day of February 2025

Sachin Manocha
[IN/PA-3247]
Of KRIA Law
Agent for Applicant
,CLAIMS:We Claim

1. A flame arrestor device (100), comprising:
an inlet conduit (110) for receiving fluid;
an outlet conduit (130) for discharging the fluid;
an outer chamber (120) connecting the inlet conduit (110) and the outlet conduit (130), the outer chamber (120) comprising one or more chambers (123, 124, 126) including:
a funnel conduit (122) connected to the inlet conduit (110) and configured to receive the fluid from the inlet conduit (110), the funnel conduit (122) extending across the one or more chambers (123, 124, 126) in a first direction;
a flow regulator (127) extending from the funnel conduit (122) in the first direction, the flow regulator (127) including at least one material (152);
at least one first resilient element (125) connecting the flow regulator (127) with walls of the one or more chambers (123, 124, 126) in a second direction being perpendicular to the first direction, and
at least one second resilient element (129) arranged between the flow regulator (127) and the outlet conduit (130) along the first direction,
wherein the outlet conduit (130) includes a flow conditioner (128) connected with the at least one second resilient element (129) along a third direction opposite to the first direction.

2. The flame arrestor device (100) as claimed in claim 1, wherein the one or more chambers (123, 124, 126) comprises:
a first chamber (123) connected to the inlet conduit (110),
a second chamber (124), and
a third chamber (126) connected to the outlet conduit (130),
wherein the second chamber (124) is arranged between the first chamber (123) and the third chamber (126) across the first direction.

3. The flame arrestor device (100) as claimed in claim 2, wherein the first chamber (123) comprises one or more particles (160), the one or more particles (160) being a globule filled with fire-extinguishing substances.

4. The flame arrestor device (100) as claimed in any one of claims 2 or 3, wherein the second chamber (124) comprises one or more porous substances (162).

5. The flame arrestor device (100) as claimed in any one of claims 2 to 4, wherein the third chamber (126) includes the flow regulator (127), and wherein the at least one first resilient element (125) is configured to connect the flow regulator (127) with walls of the third chamber (126) in the second direction.

6. The flame arrestor device (100) as claimed in any one of claims 2 to 5, wherein the funnel conduit (122) extends across the first chamber (123) and the second chamber (124) in the first direction.

7. The flame arrestor device (100) as claimed in any one of claims 2 to 6, wherein the second chamber (124) is spaced apart from the first chamber (123) by a perforated globule retainer (164).

8. The flame arrestor device (100) as claimed in any one of claims 2 to 7, wherein the first chamber (123), the second chamber (124) and the third chamber (126) are configured to absorb and dissipate heat from entering through outlet conduit (130).

9. The flame arrestor device (100) as claimed in any one of claims 1 to 8,
wherein the funnel conduit (122) comprising a first opening (132) and a second opening (134) being smaller than the first opening (132), and
wherein the first opening (132) being configured to overlap an opening of the inlet conduit (110) in the first direction and the second opening (134) being configured to receive the flow regulator (127) in the first direction.

10. The flame arrestor device (100) as claimed in claim 9, wherein the funnel conduit (122) comprises:
an anchoring strut (142) arranged at the first opening (132) in the second direction; and
at least one third resilient element (144) connecting the anchoring strut (142) to the flow regulator (127) along the first direction.

11. The flame arrestor device (100) as claimed in claim 1,
wherein the inlet conduit (110) comprises at least one inner perforated tube (112) formed along walls of the inlet conduit (110), the at least one inner perforated tube (112) including one or more particles (160) being a globule filled with fire-extinguishing substances; and
wherein the outlet conduit (130) comprises at least one inner perforated tube (114) formed along walls of the outlet conduit (130), the at least one inner perforated tube (114) including one or more particles (160) being a globule filled with fire-extinguishing substances.

12. The flame arrestor device (100) as claimed in claim 1, wherein the outer chamber (120) comprises one or more joints (150).

13. The flame arrestor device (100) as claimed in claim 1, wherein the flow conditioner (128) comprises a matrix of passages (135), the passages (135) being configured to receive the fluid from the outer chamber (120) and dispense the fluid to the outlet conduit (110).

14. The flame arrestor device (100) as claimed in claim 1, wherein the at least one second resilient element (129) is at least one of a sacrificial resilient element or a tension spring.

15. The flame arrestor device (100) as claimed in claim 9,
wherein, in a first state, the flow regulator (127) is configured to move towards the flow conditioner (128) in the first direction while being spaced apart from the second opening (134) of the funnel conduit (122) by means of the at least one third resilient element (144) and the at least one first resilient element (125), and
wherein the first state being a state of normal flow of fluid.

16. The flame arrestor device (100) as claimed in claim 9,
wherein the flow regulator (127) includes the at least one material (152) covered by a lid (170), the at least one material (152) includes fire-extinguishing substances,
wherein, in a second state, the flow regulator (127) is configured to move towards the first opening (132) of the funnel conduit (122) in the third direction while being detached from the at least one second resilient element (129) by means of the lid (170),
wherein the flow regulator (127), in the second state, is configured to release the at least one material (152), and
wherein the second state being a state of reverse flow of fluid.

Dated this 21st day of February 2025

Sachin Manocha
[IN/PA-3247]
Of KRIA Law
Agent for Applicant