JP4936750B2 - Fuel supply system - Google Patents

Description

  The present invention relates to a fuel supply method and a fuel supply system for a transport vehicle that transports LNG (Liquefied Natural Gas) in a container, and more particularly to a fuel supply for a natural gas transport vehicle that travels using natural gas as a fuel.

  Conventionally, in order to transport LNG, LNG containers are transported by a trailer such as a diesel engine. A so-called bulk transportation method is known as one of the typical transportation methods for container transportation. In this bulk transport, a tank-shaped transport container containing LNG is placed on a predetermined container stand, and the container stand on which the container is placed is pulled by the trailer body.

  In recent years, trailers that perform container transportation including bulk transportation have been used not by diesel engines but by LNG automated workers, CNG automated trainers, etc., for reasons such as environmental conservation through exhaust gas reduction.

  In addition, as a natural gas vehicle, a CNG vehicle that stores natural gas as fuel for an engine in a high pressure gas state (about 20 MPa) in a CNG (Compressed Natural Gas) tank, in a liquid state (−160 ° C., about 0.01 MPa) LNG automobiles and the like that are stored are known, and these natural gas automobiles are becoming more popular in recent years because they have less adverse effects on the environment than gasoline automobiles. In addition to the above two types, the development of AMG (Absorbed Natural Gas) that adsorbs natural gas to an adsorbent in the tank, stores the pressure at several MPa and supplies it to the engine has been started.

  In the CNG automobile, a pressure reducing valve is provided in a fuel system from the CNG tank to the engine. A system in which CNG is reduced to about 0.4 MPa by this pressure reducing valve is mixed with air, supplied to the engine, and burned in the engine.

  In the LNG automobile, an evaporator using, for example, waste heat of the engine is provided in a fuel path from the LNG tank that stores the cryogenic LNG to the engine. Then, LNG sent out from the LNG tank is vaporized, mixed with air, supplied to the engine, and burned in the engine. These natural gas vehicles are disclosed in many documents including Patent Document 1, for example.

JP-A-7-290980

  However, although the transport container that accommodates the LNG during transport is formed of a heat-insulating material, it is not complete, and the LNG inside the transport container partially vaporizes due to heat input from the outside. BOG (boil off gas). And this BOG raises the temperature and pressure (bulk pressure) inside the transport container, and vaporization of LNG inside the transport container further proceeds.

  Conventionally, in order to prevent such a situation, a part of the BOG is taken out from the container and discarded. However, the discarded BOG is wasted without being used at all, and there is a problem that it is against the trend of effective use of resources.

The present invention has been made in view of such circumstances, and the object thereof is to enable transport of liquefied natural gas without wasting boil-off gas generated in a transport container that contains liquefied natural gas. It is to provide a fuel supply system for transport vehicles.

The fuel supply system according to claim 1 , wherein the boil-off gas generated in the transport container is pressurized by a pressurizing means in a fuel supply system to a transport vehicle having a transport container for storing liquefied natural gas. A boil-off gas supply unit that is supplied to the traveling fuel system side of the transport vehicle, and a boil-off gas that is provided in the traveling fuel system and that is supplied from the boil-off gas supply unit is adapted to the drive unit of the transport vehicle. It possesses a gas adjustment unit which adjusts the said transporter is a compressed natural gas vehicle, the traveling fuel system has a travel fuel storage tank for storing natural gas fuel for running at a predetermined pressure, The pressurizing means of the boil-off gas supply unit is configured so that the boil-off gas is supplied at least from the traveling natural gas supplied from the traveling fuel storage tank to the gas adjusting unit. Characterized in that pressurized to have a pressure.

  According to this, the boil-off gas generated in the transportation container is pressurized by the boil-off gas supply unit and supplied to the traveling fuel system side. Then, the supplied boil-off gas is adjusted by the gas adjusting unit of the traveling fuel system so as to fit the driving unit. Accordingly, since the boil-off gas generated in the transport container can be used as a travel fuel for the transport vehicle, the boil-off gas can be effectively used as a transport vehicle fuel without being discarded and wasted.

In addition, the amount of natural gas fuel replenished from a fuel replenishing device such as a quick filling device can be reduced in advance for the amount covered as fuel for the boil-off gas, and the transportation cost can be reduced. Since the pressurized boil-off gas has a higher pressure than the natural gas supplied from the traveling fuel tank to the gas adjustment unit, the boil-off gas supply unit can reliably supply the gas adjustment unit.
The fuel supply system according to claim 2 is characterized in that the boil-off gas is pressurized to a pressure higher than 20 MPa.

Transporter fuel delivery system of claim 3, wherein in the invention according to claim 1 or 2, the gas passage from the BOG supply unit to the gas conditioning unit, the opening and closing of the gas passage An opening / closing means for turning on / off the supply of the pressurized boil-off gas is provided. Thereby, the permission and stop of supply of the boil-off gas from the boil-off gas supply unit to the gas adjustment unit can be arbitrarily switched according to the situation.

A transportation vehicle fuel supply system according to a fourth aspect is the invention according to any one of the first to third aspects, wherein the pressure is applied to a gas passage from the boil-off gas supply unit to the gas adjustment unit. Further, a backflow prevention means for preventing backflow of the boil-off gas is provided. Thereby, the trouble which arises by a backflow can be prevented.

  According to the fuel supply method and the fuel supply system according to the present invention, liquefied natural gas can be transported without discarding the boil-off gas generated in the transport container.

  Further, by using the boil-off gas as fuel, it is possible to reduce the amount of natural gas fuel replenished in advance from a fuel replenishing device such as a rapid filling device, thereby reducing transportation costs.

  FIG. 1 shows an embodiment of a fuel supply system for executing a fuel supply method according to the present invention, and schematically shows an example in which a bulk transport vehicle 10 is used as a transport vehicle. As shown in the figure, a bulk transport vehicle 10 includes a trailer body 12 having a drive mechanism such as an engine that drives natural gas as fuel, and an LNG container as a substantially cylindrical transport container containing a predetermined amount of LNG therein. A bulk 16 with 14.

  The LNG container 14 communicates with a natural gas fuel system 18 and an engine 22 as a drive unit via a boil-off gas supply unit (BOG supply unit) 20 described later.

  Hereinafter, an example in which the fuel supply system is applied to a CNG vehicle will be described as a first embodiment, and an example in which the fuel supply system is applied to an LNG vehicle will be described as a second embodiment.

(First embodiment)
FIG. 2 is a fuel system diagram of the transport vehicle including the fuel supply system according to the first embodiment. First, the natural gas fuel system 18 will be described.

  The natural gas fuel system 18 has substantially the same configuration as a known fuel system (CNG fuel system) for CNG automobiles, and has a CNG storage tank 24 as a natural gas storage tank that stores CNG at a pressure of about 20 MPa. is doing. The CNG storage tank 24 communicates with a gas filling port 32, a gas filling valve 36, and a gas adjusting unit 38 described later via gas pipes 26 and 28. Further, the CNG storage tank 24 is provided with a main valve 24a that stops the gas inside the CNG storage tank 24 in a closed state and allows gas to flow out in an open state.

  A gas pipe 28 communicates with the gas pipe 26 at a branch point A. The gas pipe 28 branches into a fuel supply pipe 28a from the outside and a fuel supply pipe 28b to the engine at the branch point A. is doing. The external fuel supply pipe 28a communicates with the gas filling port 32, the gas filling valve 36, and the check valve 34, which are connected to the natural gas fuel system 18 by an external fuel supply means such as a quick filling device (not shown). For supplying compressed natural gas.

  The fuel supply pipe 28b to the engine communicates with the gas adjusting unit 38 and the engine 22. The gas adjusting unit 38 includes a first pressure sensor 42 having a main stop valve 40 and a pressure gauge 50 from the upstream side, a fuel cutoff. A valve 44, a pressure reducing valve 46, and a second pressure sensor 48 are provided. The main stop valve 40 is for shutting off the supply of fuel to the engine 22 by shutting off natural gas when trouble occurs due to damage to the gas pipe in the closed state.

  The first pressure sensor 42 measures the pressure of natural gas at this position, and displays it on the pressure gauge 50 using data transmission means (not shown). The fuel shut-off valve 44 partially shuts off the natural gas in order to adjust the natural gas to an appropriate amount as fuel supplied to the engine 22.

  The pressure reducing valve 46 depressurizes the natural gas so that the natural gas has an appropriate pressure as fuel supplied to the engine 22. The second pressure sensor measures the pressure of natural gas immediately before being supplied to the engine 22, and has a control means (not shown) that performs opening / closing control of the main stop valve 40. Therefore, for example, when the natural gas pressure is greatly deviated from a predetermined pressure due to some trouble, the control means closes the main stop valve 40 and stops the fuel supply.

  In the natural gas fuel system 18 of the present embodiment, as a characteristic configuration different from the known configuration, the fuel supply pipe 28b to the engine is supplied with a BOG at the branch point B, that is, upstream of the gas adjustment unit 38. A communication part to the supply pipe 56 for receiving the supply of compressed natural gas from the part 20 is provided.

  Next, the LNG container 14 and the BOG supply unit 20 will be described. The LNG container 14 accommodates a predetermined amount of LNG inside as described above, and has a steam port 14a at the top. The steam port 14 a is generated inside the LNG container 14 to flow BOG to the gas pipe 52.

  The BOG supply unit 20 supplies BOG generated in the LNG container 14 to the natural gas fuel system 18, and pressurizes and compresses the BOG supplied through the gas pipe 52 from the steam port 14a of the LNG container 14. A compressor 54 as a pressurizing means is provided. In the present embodiment, the compressor 54 uses the BOG as a compressed natural gas of about 21 Mpa.

  Thereby, the BOG generated in the LNG container 14 can be compressed by the compressor 54 to make the BOG a compressed natural gas suitable for supply to the natural gas fuel system 18.

  Further, since the pressure (21 Mpa) of the compressed natural gas is higher than the pressure (20 Mpa) of CNG flowing through the gas pipe 28, the compressed natural gas naturally flows through the supply pipe 56 to the branch B. Thereby, the supply of the compressed natural gas from the BOG supply unit 20 to the gas adjustment unit 38 can be easily performed without using a special device or the like.

  The compressor 54 communicates the container main valve 58 and the check valve 60 with the branch B described above via the supply pipe 56. The container main valve 58 as an opening / closing means allows passage of the compressed natural gas from the compressor 54 in the opened state and blocks passage of the compressed gas in the closed state, and is opened by a predetermined control means (not shown). Switch between state and blocked state. As a result, it is possible to switch between allowing and stopping the supply of compressed natural gas from the compressor 54 to the natural gas fuel system 18 depending on the situation. Note that the switching of the opening and closing of the container original valve 58 may be performed manually.

  The check valve 60 serving as a backflow prevention means is provided downstream of the container main valve 58 and blocks the natural gas flowing from the natural gas fuel system 18 toward the compressor 54, that is, the compressor 54 seems to have a problem. In such a case, the backflow is prevented from occurring. Thereby, the trouble by backflow is prevented.

  Next, an example of an operation state when bulk transportation is performed using the fuel supply system of the present embodiment having the above-described configuration will be described based on the configuration of FIG. 2 and the flowchart shown in FIG. It is assumed that a predetermined amount of CNG is stored in the CNG storage tank 24 from the outside by a quick filling device or the like, and basically the bulk transport vehicle 10 is running using this CNG as fuel. .

  In step S <b> 101, during the travel of the bulk transport vehicle 10, a predetermined amount of BOG generated in the LNG container 14 flows from the steam port 14 a of the LNG container 14 through the gas pipe 52 to the compressor 54. As a matter of course, BOG flows to the compressor 54 even when the bulk transport vehicle 10 is stopped.

  In step S102, the compressor 54 pressurizes the BOG to obtain a predetermined compressed natural gas. In the present embodiment, as described above, the pressure of the compressed natural gas is about 21 MPa.

  In step S103, the container former valve 58 is opened. Since the compressed natural gas has a pressure higher than that of CNG flowing in the fuel supply pipe 28b to the engine of the natural gas fuel system 18, it passes from the compressor 54 through the supply pipe 56 to the natural gas fuel system 18 side. Flows naturally. The container main valve 58 may be opened when the above-described supply of fuel from the outside is completed.

  In step S104, the compressed natural gas flowing through the supply pipe 56 flows from the branch point B through the fuel supply pipe 28b to the engine toward the gas adjusting unit 38. Then, the fuel cut-off valve 44 and the pressure reducing valve 46 are adjusted to an appropriate amount and pressure for supplying the compressed natural gas to the engine 22 and supplied to the engine 22. Further, the check valve 34 can prevent the compressed natural gas from flowing through the fuel supply pipe 28a from the outside toward the gas filling valve 36.

  A part of the compressed natural gas flows to the CNG storage tank 24. However, since all the gas in the CNG storage tank is supplied to the engine 22 as a result, the part of the compressed natural gas is wasted. There is nothing.

  When the bulk transport vehicle 10 is stopped or the like, fuel is not supplied to the engine 22, that is, when the main stop valve 40 is closed, almost all of the compressed natural gas flows and is stored in the CNG storage tank 24. The The compressed natural gas stored in the CNG storage tank 24 can be used after the fuel supply to the engine 22 is started. Thus, the BOG generated in the LNG container 14 is used as fuel for the engine 22 without waste.

  Due to the operating state as described above, the BOG generated in the LNG container 14 can be supplied to the natural gas fuel system 18 by the BOG supply unit 20 and used as the fuel for the engine of the bulk transport vehicle 10, so that the BOG is not discarded. It can be effectively used as a fuel for the bulk transport vehicle 10. As a result, the amount of natural gas fuel to be replenished in advance from a fuel replenishing device such as a quick filling device can be reduced for the amount of fuel used in the bulk transport vehicle covered by the BOG generated in the LNG container 14, Transportation costs can be reduced.

  Therefore, the bulk transport requester transports the LNG in the LNG container 14 owned by the bulk transporter as part of the fuel. Accordingly, since the fuel cost for transportation borne by the carrier can be reduced, the transportation cost paid to the carrier can be reduced as a result.

(Embodiment 2)
FIG. 4 is a fuel system diagram of a transport vehicle including the fuel supply system according to the present embodiment. In addition, the same code | symbol is attached | subjected to the element similar to 1st Embodiment, and the description is abbreviate | omitted. Further, a mechanism for supplying fuel from the outside by a rapid filling device or the like is not shown for the sake of simplification of the drawing.

  First, the natural gas fuel system 61 will be described. The natural gas fuel system 61 has substantially the same configuration as a known fuel system (LNG type fuel system) mounted on an LNG vehicle, and has an LNG storage tank 62 that stores LNG. The LNG storage tank 62 communicates with the gas adjustment unit 38 via the gas pipe 63 and the fuel supply pipe 28b. In addition, the LNG storage tank 62 is provided with a main valve 62a that stops the gas inside the LNG storage tank 24 in a closed state and allows gas to flow out in an open state.

The gas pipe 63 is provided with an evaporator 68 and a check valve 70 between the main valve 62 b and the branch C. The evaporator 68 is, for example, a device that vaporizes the liquefied natural gas from the LNG storage tank 62 using the waste heat of the engine 22 to make it a vaporized natural gas, and the check valve 70 prevents backflow that prevents backflow. Means, that is, natural gas is prevented from flowing from the branch C into the LNG storage tank 62. In the gas pipe 63, the direction of the arrow 101 is the rectification direction.
Further, the gas pipe 63 communicates with the fuel supply pipe 28b to the engine at the branch C, whereby the vaporized natural gas from the evaporator flows into the gas adjusting unit 38 and is then supplied to the engine 22. Is done.

  Further, as a characteristic configuration different from the known configuration in the natural gas fuel system 61 of the present embodiment, the fuel supply pipe 28b to the engine communicates with the BOG supply unit 20 on the side opposite to the gas adjustment unit 38 via the branch C. is doing.

  The LNG storage tank 62 and the compressor 54 of the BOG supply unit 20 may be communicated with each other through a predetermined gas pipe, and a reliquefaction device may be provided there. As a result, for example, even if the BOG is generated more than the amount of fuel temporarily supplied to the engine 22 due to, for example, the bulk transport vehicle 10 being stopped for a long time, the compressed natural gas from the compressor 54 is liquefied and LNG Since it can be stored in the storage tank 62, waste of BOG can be further suppressed.

  On the other hand, as in the first embodiment, the compressed natural gas supplied from the BOG supply unit 20 to the fuel supply pipe 28b to the engine flows directly to the gas adjustment unit 38 through the fuel supply pipe 28b to the engine. This is supplied to the engine 22.

  Therefore, as in the first embodiment, BOG generated in the LNG container 14 can be supplied to the natural gas fuel system 61 by the BOG supply unit 20 and used as the fuel for the engine of the bulk transport vehicle 10. It can be effectively used as fuel for the bulk transport vehicle 10 without being discarded.

  The fuel supply system according to the first and second embodiments is not only applied to a transport vehicle dedicated to natural gas, but is a bi-fuel vehicle that travels with two types of fuel and mixes two types of fuel. It is also possible to apply the present invention to a hybrid vehicle that combines other drive units such as a dual fuel vehicle and an electric motor.

It is external appearance explanatory drawing of the bulk transport vehicle provided with the fuel supply system which concerns on 1st, 2nd embodiment. It is a fuel system diagram of a transportation vehicle provided with the fuel supply system concerning a 1st embodiment. It is a flowchart which shows the operation state of 1st Embodiment. It is a block diagram which shows the structure of the fuel supply system concerning 2nd Embodiment.

Explanation of symbols

10 Bulk transport vehicles (transport vehicles)
14 LNG container (container for transportation)
18 Natural gas fuel system 20 BOG supply section (boil-off gas supply section)
22 Engine (drive unit)
38 Gas adjustment part 54 Compressor (pressurizing means)
58 Container valve (opening / closing means)
60 Check valve (back flow prevention means)
61 Natural gas fuel system

Claims (4)

In a fuel supply system to a transport vehicle equipped with a transport container for storing liquefied natural gas,
A boil-off gas supply unit that pressurizes the boil-off gas generated in the transport container by a pressurizing means and supplies the boil-off gas to the traveling fuel system side of the transport vehicle;
A gas adjusting unit that is provided in the fuel system for traveling and adjusts the boil-off gas supplied from the boil-off gas supply unit so as to be adapted to the drive unit of the transport vehicle;
I have a,
The transport vehicle is a compressed natural gas vehicle;
The traveling fuel system has a traveling fuel storage tank that stores traveling natural gas fuel at a predetermined pressure,
The pressure supply means of the boil-off gas supply unit pressurizes the boil-off gas at a pressure higher than at least the travel natural gas supplied from the travel fuel storage tank to the gas adjustment unit. system. The fuel supply system according to claim 1, wherein the boil-off gas is pressurized to a pressure higher than 20 MPa. In the gas passage from the boil-off gas supply unit to the gas adjustment unit,
3. The fuel supply system according to claim 1, further comprising an opening / closing means for turning on / off the supply of the pressurized boil-off gas by opening / closing the gas passage. In the gas passage from the boil-off gas supply unit to the gas adjustment unit,
The fuel supply system according to any one of claims 1 to 3, further comprising a backflow prevention means for preventing backflow of the pressurized boil-off gas.

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