Indoor safety device, a liquefied fuel gas system and a vehicle

Abstract

The invention relates to an indoor safety device for a liquefied fuel gas system, the system comprising a storage device storing liquefied fuel gas; a vent member arranged in fluid communication with the gas inside the storage device; and a safety valve arranged to evacuate gas when the pressure inside the storage device exceeds a predetermined first value, the safety device comprising: a vent coupling; a pressure relief valve arranged downstream of the vent coupling; and a conduit for conveying gas, adapted to be connected to the pressure relief valve, the safety device being removably connected to the system by connecting the vent coupling to the vent member, wherein the pressure relief valve is configured to release gas when the pressure inside the storage device exceeds a predetermined second value, lower than the first value.

Claims

1. An indoor safety device for a liquefied fuel gas system, wherein the liquefied fuel gas system comprises: at least one storage device storing liquefied fuel gas; a vent member arranged in fluid communication with the gas inside the storage device; and at least one safety valve arranged to automatically release gas from the storage device independent of the vent member when the pressure inside the storage device exceeds a predetermined first pressure value, the indoor safety device comprising: a vent coupling; a pressure relief valve configured to be arranged downstream of the vent coupling; and a conduit for conveying gas comprising an inlet configured to be connected to the pressure relief valve, wherein the indoor safety device is configured to be removably connected to the liquefied fuel gas system by connecting the vent coupling to the vent member, wherein the pressure relief valve is configured such that it opens when the pressure inside the storage device exceeds a predetermined second pressure value to thereby vent gas from inside the storage device via the vent member and through the conduit, and wherein the predetermined second pressure value is lower than the predetermined first pressure value, such that the pressure relief valve is configured to relieve pressure from the storage device prior to the pressure in the storage device reaching the first pressure value where gas would be released via the at least one safety valve to thereby prevent unwanted release of gas from the at least one safety valve.

2. The indoor safety device according to claim 1, wherein the conduit is configured to convey the released gas to an outside environment.

3. The indoor safety device according to claim 1, wherein the conduit for conveying gas is a flexible hose.

4. The indoor safety device according to claim 1, wherein the predetermined second value is between 14-15.5 bar.

5. The indoor safety device according to claim 1, wherein the vent coupling comprises a female quick disconnect valve, configured to be connected to the vent member of the liquefied fuel gas system.

6. The indoor safety device according to claim 1, further comprising: a restrictor configured to be arranged downstream of the vent coupling.

7. The indoor safety device according to claim 1, wherein the pressure relief valve is configured to allow manual opening of the valve.

8. A liquefied fuel gas system, comprising: at least one storage device storing liquefied fuel gas; a vent member arranged in fluid communication with the gas inside the storage device; at least one safety valve arranged to automatically release gas from the storage device independent of the vent member when the pressure inside the storage device exceeds a predetermined first pressure value; and an indoor safety device comprising: a vent coupling; a pressure relief valve configured to be arranged downstream of the vent coupling; and a conduit for conveying gas comprising an inlet configured to be connected to the pressure relief valve, wherein the indoor safety device is configured to be removably connected to the liquefied fuel gas system by connecting the vent coupling to the vent member, wherein the pressure relief valve is configured such that it opens when the pressure inside the storage device exceeds a predetermined second pressure value to thereby vent gas from inside the storage device via the vent member and through the conduit, and wherein the predetermined second pressure value is lower than the predetermined first pressure value, such that the pressure relief valve is configured to relieve pressure from the storage device prior to the pressure in the storage device reaching the first pressure value where gas would be released via the at least one safety valve to thereby prevent unwanted release of gas from the at least one safety valve.

9. The liquefied fuel gas system according to claim 8, wherein the vent member comprises a male quick disconnect valve, which requires connection to the vent coupling to open.

10. The liquefied fuel gas system according to claim 8, wherein the indoor safety device is connected to the storage device when the system is in an indoor environment.

11. The liquefied fuel gas system according to claim 8, further comprising: a vent valve arranged upstream of the vent member, wherein the vent valve is configured to be in an open position when the indoor safety device is used.

12. A vehicle comprising a liquefied fuel gas system comprising: at least one storage device storing liquefied fuel gas; a vent member arranged in fluid communication with the gas inside the storage device; at least one safety valve arranged to automatically release gas from the storage device independent of the vent member when the pressure inside the storage device exceeds a predetermined first pressure value; and an indoor safety device comprising: a vent coupling; a pressure relief valve configured to be arranged downstream of the vent coupling; and a conduit for conveying gas comprising an inlet configured to be connected to the pressure relief valve, wherein the indoor safety device is configured to be removably connected to the liquefied fuel gas system by connecting the vent coupling to the vent member, wherein the pressure relief valve is configured such that it opens when the pressure inside the storage device exceeds a predetermined second pressure value to thereby vent gas from inside the storage device via the vent member and through the conduit, and wherein the predetermined second pressure value is lower than the predetermined first pressure value, such that the pressure relief valve is configured to relieve pressure from the storage device prior to the pressure in the storage device reaching the first pressure value where gas would be released via the at least one safety valve to thereby prevent unwanted release of gas from the at least one safety valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For fuller understanding of the present invention and further objects and advantages of it, the detailed description set out below should be read together with the accompanying drawings, in which the same reference notations denote similar items in the various diagrams, and in which:

(2) FIG. 1 schematically illustrates a vehicle according to an embodiment of the invention;

(3) FIG. 2 schematically illustrates a liquefied fuel gas system according to an embodiment of the invention; and

(4) FIG. 3 schematically illustrates an indoor safety device according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) FIG. 1 schematically shows a side view of a vehicle 1 according to an embodiment of the invention. The vehicle 1 comprises a propulsion unit 2. The propulsion unit 2 is suitably a gas engine. The vehicle 1 may further comprise a liquefied fuel gas system 10 for supplying liquefied fuel gas to the gas engine 2. The liquefied fuel gas system 10 may comprise an indoor safety device 100. The liquefied fuel gas system 10 and the indoor safety device 100 are further described in FIG. 2 and FIG. 3. The vehicle 1 can be any kind of vehicle comprising a gas engine. Examples of vehicles comprising a gas engine are trucks, busses, boats, passenger cars, construction vehicles, and locomotives. The present invention can also be used in connection with any other platform than vehicles, as long as this platform comprises a gas engine. One example is a power plant with a gas engine.

(6) In the following, the liquefied fuel gas system 10 will be described as it can be embodied when using it in a vehicle 1. As a consequence, not all components in the description are necessary. They are, however, added in the description for showing a preferred embodiment of the present disclosure.

(7) FIG. 2 schematically shows a liquefied fuel gas system 10 according to an embodiment of the invention. The system 10 comprises: at least one storage device 12 storing liquefied fuel gas; at least one safety valve 14 arranged to release gas from the storage device 12 when the pressure inside the storage device 12 exceeds a predetermined first value; and a vent member 16 arranged in fluid communication with the gas inside the storage device 12. The system 10 further comprises an indoor safety device 100. The indoor safety device 100 comprises a vent coupling 110; a pressure relief valve 120 adapted to be arranged downstream of the vent coupling 110; and a conduit 130 for conveying gas, adapted to be connected to the pressure relief valve 120. The indoor safety device 110 is adapted to be removably connected to the liquefied fuel gas system 10 by connecting the vent coupling 110 to the vent member 16, wherein the pressure relief valve 120 is configured to release gas when the pressure inside the storage device 12 exceeds a predetermined second value. The predetermined second value is lower than the predetermined first value.

(8) The liquefied fuel gas system 10 is suitably adapted to be arranged on a vehicle 1 as disclosed in FIG. 1. The system 10 is thus suitably adapted to supply fuel gas to a gas engine as disclosed in FIG. 1. The liquefied fuel gas system 10 comprises at least one passage (not shown) for transporting the fuel gas from the storage device 12 to the gas engine.

(9) The indoor safety device 100 is adapted to be connected to the vent member 16 only when the system 10/vehicle 1 is indoors. The conduit 130 of the indoor safety device 100 is configured to convey the released gas to an outdoor environment. By connecting the indoor safety device 100 to the vent member 16 gas from the storage device 12 will be released via the vent member 16 and the indoor safety device 100 to an outdoor environment instead of via the at least one safety valve 14.

(10) The conduit 130 may be adapted to be mounted directly on the pressure relief device 120. The conduit 130 may comprise a flexible hose. The flexible hose may be a cryogenic hose or a simple garden hose. Alternatively or additionally, the conduit 130 comprises a pipe or tube.

(11) The at least one safety valve 14 of the system 10 may be configured to open when the pressure inside the storage device 12 exceeds 15.8 bar. The system 10 may comprise a secondary safety valve (not shown) which is configured to open when the pressure inside the storage device 12 exceeds 24 bar. This way, it is ensured that gas will be released even if the at least one safety valve 14 malfunctions. The pressure relief valve 120 of the indoor safety device 100 may be configured to open when the pressure inside the storage device 12 exceeds 14 bar. The predetermined second value may be between 14-15.5 bar.

(12) The vent coupling 110 of the indoor safety device 100 may comprise a female quick disconnect valve, adapted to be connected to the vent member 16 of the liquefied fuel gas system 10. The vent member 16 may comprise a male quick disconnect valve, which requires connection to the vent coupling 110 for opening the valve. The vent member 16 is arranged to allow venting of the storage device 12 for example during refueling. The vent member 16 is normally in a closed position, such that no gas can be released via the vent member 16. In order to open the vent member 16 a vent coupling, such as the vent coupling 110 of the indoor safety device 100, must be connected to the vent member 16, whereby the vent member 16 opens and gas can be released from the storage device 12. The vent member 16 may comprise guide pins and the vent coupling 110 may comprise grooves adapted to interact with the pins of the vent member 16, such that the vent coupling 110 easily is accurately positioned. Thus, the vent member 16 and the vent coupling 110 may together form a bayonet coupling. When the vent coupling 110, and thus the indoor safety device 100, is connected to the vent member 16, boil-off gas can be released from the storage device 12 via the vent member 16 into the vent coupling 110 and on to the pressure relief valve 120. If the pressure of the gas exceeds the predetermined second value, the pressure relief valve 120 opens and the boil-off gas is released to the conduit 130 and on to the outdoor environment.

(13) The system 10 may further comprise a vent valve 18 arranged upstream of the vent member 16, wherein the vent valve 18 should be in an open position when the indoor safety device 100 is used. The vent valve 18 is suitably a screw down valve which normally is in a closed position. Thus, when the vehicle 1 is operating the vent valve 18 is closed and no gas inside the storage device 12 can reach the vent member 16. When the indoor safety device 100 is connected to the vent member 16 the vent valve 18 is suitably manually operated to an open position. This way, gas can reach the vent member 16 and be released via the indoor safety device 100.

(14) The system 10 also comprises a pipe arrangement 20 arranged in fluid communication with the at least one safety valve 14. The pipe arrangement 20 may also be referred to as a “boil-off pipe” and is adapted to release boil-off gas from the storage device 12 when the safety valve 14 is open. The end of the pipe arrangement 20 through which the boil-off gas is discharged, is typically arranged at a high point on the vehicle 1. In this figure the liquefied fuel gas system 10 only comprises one storage device 12. It is, however, to be understood that the system 10 may comprise a plurality of storage devices 12. In such cases, all storage devices 12 are suitably connected to the same pipe arrangement 20.

(15) The liquefied fuel gas which is stored in the storage device 12 may be liquefied natural gas, LNG. LNG is a common two-phase gas which can be used for propelling vehicles. LNG is usually stored below −110 degree Celsius in the storage device 12. The storage device 12 may be a cryogenic gas tank.

(16) The system 10 may comprise a pressure regulator (not shown) arranged downstream of the storage device 12. The system 10 may further comprise a heat exchanger device (not shown) arranged downstream of the pressure regulator. The heat exchange device may use cooling water from the gas engine to heat the fuel gas coming from the pressure regulator. This assures that fuel gas drawn from the liquid phase in the storage device will be converted into its gaseous phase before reaching the gas engine. The heat exchanger device also ensures that the gas reaching the gas engine has a temperature that the gas engine can handle.

(17) The system 10 may further comprise a gas regulator system (not shown) arranged downstream of the heat exchanger device. The gas engine has a preferred input gas pressure. This preferred input gas pressure may be supplied by the gas regulator system. In one example, the preferred input gas pressure is around 7 bar. The at least one passage may comprise a section arranged to transport fuel gas from the heat exchange system or the gas regulator system to the gas engine.

(18) The system 10 may also comprise a so called pressure build up device (not shown), arranged to add energy to the system 10 in order to maintain a certain pressure. A pressure build up device may be arranged to transfer energy from outgoing heated fuel gas in gaseous phase to the fuel gas in liquid phase in the storage device 12, to increase the pressure in the storage device 12.

(19) FIG. 3 schematically illustrates an indoor safety device 100 for a liquefied fuel gas system 10 according to an embodiment of the invention. The indoor safety device 100 is suitably configured as disclosed in FIG. 2 with the difference that it further comprises a restrictor 140 adapted to be arranged downstream of the vent coupling 110. The restrictor 140 is adapted to restrict the flow of gas from the storage device 12, such that the cold gas does not cause problems for the material of the conduit 130. This way, a simple garden hose may be used as a conduit 130. During short periods of time indoors the restrictor 140 also reduces the amount of fuel gas being released to the atmosphere. The indoor safety device thus reduces the impact on the environment and the amount of lost fuel.

(20) The restrictor 140 is suitably adapted to be arranged downstream of the vent coupling 110 and upstream of the pressure relief valve 120 as disclosed in this figure. Alternatively, the restrictor 140 is adapted to be arranged downstream of the pressure release valve 130, in which case the conduit 130 is attached to the restrictor 140. The restrictor 140 may comprise a channel having a diameter considerably smaller than the diameter of the vent coupling 110.

(21) The foregoing description of the preferred embodiments of the present invention is provided for illustrative and descriptive purposes. It is not intended to be exhaustive or to restrict the invention to the variants described. Many modifications and variations will obviously be apparent to one skilled in the art. The embodiments have been chosen and described in order best to explain the principles of the invention and its practical applications and hence make it possible for specialists to understand the invention for various embodiments and with the various modifications appropriate to the intended use.