JP2017003065A - Liquefied natural gas charging method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquefied natural gas charging method capable of correctly and easily detecting a terminal point of charging, in charging a liquefied natural gas to a fuel tank of a liquefied natural gas vehicle.SOLUTION: A liquefied natural gas charging method includes: a supply step for supplying a liquefied natural gas from a supply source of the liquefied natural gas to an on-vehicle tank 4 loaded on a vehicle 3 and storing the liquefied natural gas as a fuel for the vehicle 3; and a stop step for stopping the supply of the liquefied natural gas in the supply step at a timing when an internal pressure of the on-vehicle tank 4 jumps after moderately rising from an initial state at the start of the supply step. Thus a terminal point in charging can be correctly and easily detected in charging when the liquefied natural gas to the fuel tank of the liquefied natural gas vehicle 3.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquefied natural gas filling method and apparatus for a fuel container of a liquefied natural gas vehicle.

  Now, liquefied natural gas (LNG) is drawing attention as a fossil fuel. Until now, coal and oil, which have been mainstream, are concerned about the depletion of the remaining reserves. On the other hand, LNG has been rapidly put into practical use, as represented by shale gas. Such LNG is an energy source that is expected to expand its use in the future, and the amount handled is expected to increase in the future.

  For LNG transportation, pipelines are mainstream in the continents such as the United States and China. An island country such as Japan, which has a small output in its own country, is often transported by sea from other countries. In this case, LNG is handled in batches, and there are many opportunities to fill storage tanks and containers.

  In addition to using LNG as fuel in large-scale facilities such as factory plants, it is considered that the development of vehicles using LNG as a drive source will increase in the future.

  In Japan, natural gas-powered vehicles are beginning to spread mainly in urban areas. The vehicle currently used is a CNG vehicle in which a fuel container is filled with compressed natural gas (CNG). However, the CNG vehicle has a drawback that the cruising distance by one fuel filling is short. For this reason, the use of CNG vehicles is actually limited to the suburbs of urban areas.

  In the case of LNG, the energy density per unit volume is about three times as high as that of CNG. Therefore, if LNG is mounted on a fuel container and used as fuel for driving, the cruising distance will be greatly increased compared to CNG vehicles. If such an LNG vehicle is realized, not only in the suburbs of urban areas, but also the range of use such as long-distance transportation will be greatly expanded.

The present applicant has grasped the following Patent Document 1 as a prior art related to a method of filling a container with LNG.
The present applicant has grasped the following Patent Document 2 as a prior art related to a method of filling liquefied gas fuel.
The present applicant has grasped the following non-patent document 1 as a prior art related to the LNG vehicle as described above.
The present applicant grasps the following non-patent document 2 as a prior art related to a fuel container for an LNG vehicle.

Patent Document 1 relates to a method for filling liquefied natural gas. Patent Document 1 has the following description.
[wrap up]
[Problem] The boil-off gas generated during filling of liquefied natural gas from a tank lorry is used to increase the pressure in the tank lorry, thereby relaxing the restriction generated in the processing of the boil-off gas, or reducing the amount of emission to the atmosphere.
[Solution] Boil-off gas discharged from the upper part of the first storage tank 1 is passed through a part of the fourth pipe 18 through the first tank truck pipe 21 and part of the first liquefied natural gas filling pipe 2. The pressure is supplied to the bottom side of the TL, and the pressure in the first storage tank 1 is decreased and the pressure in the tank lorry TL is increased. Thereafter, the supply of the boil-off gas from the first storage tank 1 to the tank lorry TL is stopped, the pressure in the tank lorry TL is increased to the set pressure by the lorry pressurizer 29, and the tank lorry is passed through the first liquefied natural gas filling pipe 2. The liquefied natural gas in the TL is filled and supplied to the first storage tank 1.

Patent Document 2 relates to a method for filling liquefied gas fuel. Patent Document 2 has the following description.
[wrap up]
[PROBLEMS] A liquefied gas fuel charging system that allows a driver to check during operation whether or not an overflow prevention valve that prevents liquefied gas fuel from flowing out beyond a specified flow rate is operating, and the charging Provide a method.
[Solution] A pressure difference ΔP between the filling pressure Pa of the vapor phase Ga of DME in the main tank 4 and the original pressure Pb (Ps) of the vapor phase Gb (Gs) of DME in the sub tank 5 (storage tank 31). However, when the pressure difference determination value Pn is greater than or equal to the predetermined pressure determination value Pn, it is determined that the overflow prevention valve 17 blocks the flow passage 12, and the overflow prevention valve 17 blocks the flow passage 12, and the warning lamp 42 (57). CU41 (56) for lighting up.

Non-Patent Document 1 relates to the technical trend and latest examples of liquefied natural gas vehicles (LNG vehicles). Non-Patent Document 1 describes the following matters. Post a table of contents.
Item 2. Technological trends and latest examples of liquefied natural gas vehicles (LNG vehicles) Technical trends of liquefied natural gas vehicles (LNG vehicles) 2. Latest examples of liquefied natural gas vehicles (LNG vehicles) 2.1 Challenges of LNG supply equipment 2.1.1 Fuel supply equipment 2.1.2 LNG enrichment (weathering) measures 2.1.3 Gas leak detection measures 2.2 Examination of new LNG fuel supply system 2.1.1 External pressurization method 2.3 Large LNG truck technology development 2.3.1 Development target 2.3.2 Actual running test of developed large LNG truck 2.3. 3 Challenge public road running test 2.4 Future issues for improvement of large LNG truck

  Non-Patent Document 2 relates to a liquefied natural gas vehicle fuel tank. Non-Patent Document 2 describes that a small tank called an ullage tank is provided inside a fuel tank.

  The ledge tank is a space separated from the filling chamber by a partition wall and has a volume of about 10% of the entire tank. The partition has a small hole. When the filling chamber is overfilled or the internal pressure starts to rise, LNG enters the ledge tank little by little. This prevents a sudden increase in internal pressure for the entire tank. Further, by setting the ledge tank as a heat input point from the outside air, the vaporization of the liquefied gas in the filling chamber is suppressed, and the generation of boil-off gas (BOG) is minimized.

JP 2007-132490 A JP 2014-58997 A

Yuichi Goto; Next Generation Automotive Technology and Shale Revolution, Information Organization Co., Ltd., p. 70-79, (2014) LNG Vehicle Fuel System OPERATIONS MANUAL; NexGen FUELING, A Chart Industries Company

  As a method for detecting the filling amount when filling the LNG container with LNG, the following method is generally adopted. That is, it is a method of measuring the empty weight of the container itself, measuring the weight of the whole container which changes as LNG is filled, and setting the increase in weight as the LNG filling amount.

  However, in the case of an LNG container mounted as a fuel tank on an LNG vehicle, it is not possible to measure the weight by dropping the LNG container from the vehicle every time it is filled. In this case, it is conceivable to measure the weight including the vehicle. However, it is not realistic to measure the weight of a vehicle having many tons to measure the filling amount of several tens to several hundreds kg. This is because the measurement error of the measuring device itself may exceed the allowable range of the measurement error of the LNG filling amount, and the cost of the measuring device becomes unbalanced.

  Another possible method is to measure the amount of LNG weight loss on the supply side and use this to fill the LNG container. However, since a part of LNG is vaporized on the filling route, the amount of weight reduction on the supply side does not match the filling amount on the vehicle side.

  As described above, there has not been established a method for detecting an accurate LNG filling amount on the vehicle side by a simple system in an LNG container mounted as a fuel tank in an LNG vehicle.

  Also, assuming business use such as freight transportation and passenger transportation, the fuel is replenished to full tank in almost all cases. Therefore, even when LNG is filled into the LNG vehicle, it is sufficient to detect the end point of filling when the LNG is full.

  However, at present, when LNG is filled into an LNG vehicle, no method has been proposed for detecting the LNG filling amount or the filling end point when the LNG is full by a method other than weight measurement. It is.

  Patent Document 1 discloses a filling system from a tank lorry to a storage tank. However, the above-mentioned patent document 1 is only a proposal of a filling method, and does not disclose a method for detecting an end point of filling.

  Patent Document 2 discloses a method of filling a tank of a vehicle with liquefied gas fuel (dimethyl ether) from a filling stand. However, the above-mentioned Patent Document 2 is also only a proposal of a filling method, and does not disclose a method for detecting the end point of filling.

  The said nonpatent literature 1 discloses the technical trend and the latest example of a LNG vehicle. However, the said nonpatent literature 1 also does not disclose the method of detecting the end point when filling with LNG.

The said nonpatent literature 2 is related with the fuel tank for vehicles of liquefied natural gas. Non-Patent Document 2 discloses that an ledge tank is provided inside a fuel tank to prevent a rapid increase in internal pressure and suppress generation of boil-off gas (BOG). However, the said nonpatent literature 2 also does not disclose the method of detecting the end point when filling with LNG.

〔the purpose〕
The present invention has been made with the following object in order to solve the above problems.
Provided is a liquefied natural gas filling method and apparatus capable of accurately and easily detecting an end point of filling when liquefied natural gas is filled in a fuel tank of a liquefied natural gas vehicle.

In order to achieve the above object, the liquefied natural gas filling method according to claim 1 employs the following configuration.
A supply step of supplying the liquefied natural gas from a supply source of liquefied natural gas to a tank that is mounted on a vehicle and stores liquefied natural gas as fuel for the vehicle;
And a stop step of stopping the supply of the liquefied natural gas in the supply step at a timing when the internal pressure of the tank rising from the initial state suddenly increases after the start of the supply step.

The liquefied natural gas filling method according to claim 2 adopts the following configuration in addition to the configuration according to claim 1.
In the initial state, the inside of the tank has an internal pressure of 0.6 MPa or less and a temperature of −120 ° C. or less.

The liquefied natural gas filling method according to claim 3 adopts the following structure in addition to the structure according to claim 2.
Before starting the supply step, the tank is depressurized by venting the gas in the tank.

The liquefied natural gas filling method described in claim 4 employs the following configuration in addition to the configuration described in claim 2 or 3.
Before starting the supply step, the liquefied natural gas is introduced into the tank to bring the tank into the low temperature state.

The liquefied natural gas filling method according to claim 5 employs the following configuration in addition to the configuration according to any one of claims 1 to 4.
The tank includes a filling chamber filled with the liquefied natural gas by the supplying step, and a spare chamber partitioned from the filling chamber by a partition wall with a communication path.

The liquefied natural gas filling device according to claim 6 employs the following configuration in order to achieve the above object.
Supply means for supplying the liquefied natural gas from a liquefied natural gas supply source to a tank that is mounted on a vehicle and stores the liquefied natural gas as fuel for the vehicle,
When the supply means starts the supply of the liquefied natural gas, the tank has a stop means for stopping the supply of the liquefied natural gas by the supply means at a timing when the internal pressure of the tank rising from the initial state suddenly increases thereafter.

  According to the first and sixth aspects of the present invention, the liquefied natural gas is supplied from a liquefied natural gas supply source to a tank that is mounted on a vehicle and stores the liquefied natural gas as fuel for the vehicle. From the beginning to the middle of this supply, liquefied natural gas flows into the tank at a stable pace, and the amount of liquid in the tank continues to increase. At this time, the internal pressure of the tank is slightly increased from the initial state. When the tank is filled with liquefied natural gas, no more liquefied natural gas flows into the tank. On the other hand, since the liquefied natural gas, which is a supply source of liquefied natural gas, tends to move into the tank, the internal pressure of the tank rapidly increases. At this timing, the stop means stops the supply of liquefied natural gas in the supply step by the supply means. The tank is filled with liquefied natural gas. In this way, when the liquefied natural gas is filled into the fuel tank of the liquefied natural gas vehicle, the end point of the filling can be detected accurately and easily.

  The invention according to claim 2 specifies the initial state. That is, in the initial state, the inside of the tank has an internal pressure of 0.6 MPa or less and a temperature of −120 ° C. or less. If the inside of the tank is in the low pressure state and the low temperature state, the tank is in a state of accepting the supply of liquefied natural gas. That is, if the internal pressure of the tank is high, the internal pressure of the tank will rise rapidly even if liquefied natural gas is supplied from there, and a sufficient amount of liquefied natural gas cannot be filled into the tank. In addition, even if the temperature in the tank is high, even if liquefied natural gas is supplied from there, the internal pressure of the tank rapidly increases, and a sufficient amount of liquefied natural gas cannot be filled in the tank. Therefore, if the initial state of the tank is the low-pressure state and the low-temperature state, a sufficient amount of liquefied natural gas can be filled from the tank through the supply of liquefied natural gas.

  According to a third aspect of the present invention, the step of setting the tank to an initial state is specified before the supply step is started. That is, before starting the supply step, the tank is brought into the low pressure state by removing the gas from the tank. Thus, the supply step is started after the tank is surely initialized. From there, a sufficient amount of liquefied natural gas can be filled into the tank through the supply of liquefied natural gas.

  According to a fourth aspect of the present invention, the step of setting the tank to an initial state is specified before the supply step is started. That is, before starting the supply step, the liquefied natural gas is introduced into the tank to bring the tank into the low temperature state. Thus, the supply step is started after the tank is surely initialized. From there, a sufficient amount of liquefied natural gas can be filled into the tank through the supply of liquefied natural gas.

The invention according to claim 5 specifies a specific structure of the tank. In other words, the tank includes a filling chamber filled with the liquefied natural gas by the supplying step, and a spare chamber partitioned from the filling chamber by a partition wall with a communication path.
In the storage of fuel-based liquefied gas such as liquefied natural gas, the risk increases when the tank is completely filled. For example, liquefied gas is vaporized by the outside air temperature, the internal pressure rises, and there is a risk of explosion. There is also a risk of fire from fuel gas. Therefore, in order to prevent accidents due to full filling, a spare chamber is provided inside the tank.

At this time, the capacity of the preliminary chamber is preferably set to 10% by volume ± 5% by volume of the capacity of the entire tank. In other words, for liquefied natural gas users, it is desirable to fill the tank with as much liquefied natural gas as possible. If the capacity of the spare chamber is set to 10% by volume +/- 5% by volume of the capacity of the entire tank, the capacity of the filling chamber by subtracting the capacity of the spare chamber (10% by volume +/- 5% by volume of the entire tank) from the tank capacity ( The above supply step is stopped when as much liquefied natural gas as possible is filled with the upper limit of 90% by volume to 5% by volume of the entire tank. As a result, the upper limit of liquefied natural gas can be filled within a range in which safety is ensured.

It is a figure explaining the liquefied natural gas filling apparatus of 1st Embodiment of this invention. It is a figure explaining the testing apparatus of an Example. It is a figure which shows the measurement result of an Example (case 1). It is a figure which shows the measurement result of an Example (case 2).

  Next, an embodiment for carrying out the present invention will be described.

[Liquefied natural gas filling equipment]
FIG. 1 is a first embodiment showing a liquefied natural gas filling apparatus to which the present invention is applied.

  This liquefied natural gas filling device includes a supply means 1 for supplying liquefied natural gas to an in-vehicle tank 4 mounted on a vehicle 3 and a stop means 2 for stopping the supply of liquefied natural gas by the supply means 1. .

  The vehicle 3 is an automobile equipped with an engine unit 5 using natural gas as fuel. As the natural gas for the fuel, a gas obtained by evaporating the liquefied natural gas filled in the in-vehicle tank 4 with the evaporator 6 is used.

  The on-vehicle tank 4 is a low temperature liquefied gas container having a double heat insulation structure in which a vacuum heat insulating layer 4C is formed between an inner tank 4A and an outer tank 4B. A filling chamber 4D and a spare chamber 4E are provided inside the inner tank 4A. The filling chamber 4D is a space in which the liquefied natural gas is filled by the supplying step by the supplying means 1. The preliminary chamber 4E is a space partitioned from the filling chamber 4D by a partition wall 4G. The partition wall 4G is provided with a communication passage 4F, which connects the filling chamber 4D and the auxiliary chamber 4E. The partition wall 4G has a convex shape that swells toward the filling chamber 4D. The communication passage 4F is disposed below the convex top.

  The on-vehicle tank 4 is connected to a downstream end portion of a supply path 7 for supplying liquefied natural gas from the supply means 1 to the filling chamber 4D. The on-vehicle tank 4 is provided with a gas discharge path 8 for discharging the gas accumulated in the filling chamber 4D. By opening the discharge valve 8A provided in the gas discharge path 8, the gas accumulated in the filling chamber 4D can be discharged and the internal pressure of the filling chamber 4D can be lowered.

  The supply means 1 supplies the liquefied natural gas from a liquefied natural gas supply source to an in-vehicle tank 4 that is mounted on the vehicle 3 and stores liquefied natural gas as a fuel for the vehicle 3.

  The supply means 1 includes a first storage tank 11 in which liquefied natural gas supplied to the in-vehicle tank 4 is stored, and a pressurizing unit 12 for pressurizing the inside of the first storage tank 11. Yes.

  The first storage tank 11 is a low-temperature liquefied gas container having a double heat insulating structure in which a vacuum heat insulating layer 11C is formed between an inner tank 11A and an outer tank 11B. The inner space of the inner tank 11A constitutes a filling chamber 11D for storing liquefied natural gas. An upstream end of the supply path 7 is connected to the first storage tank 11. The supply path 7 takes out the liquefied natural gas stored in the filling chamber 11D and supplies it to the on-vehicle tank 4.

  The pressurizing unit 12 sends natural gas into the filling chamber 11D of the first storage tank 11 and pressurizes it. By the pressurization by the pressurization unit 12, the liquefied natural gas in the filling chamber 11D of the first storage tank 11 is taken out from the supply path 7.

  The pressurizing unit 12 includes a second storage tank 13 that stores liquefied natural gas, and an evaporator 14 that vaporizes the liquefied natural gas taken out from the second storage tank 13.

  The second storage tank 13 is a low-temperature liquefied gas container having a double heat insulating structure in which a vacuum heat insulating layer 13C is formed between an inner tank 13A and an outer tank 13B. The inner space of the inner tank 13A constitutes a filling chamber 13D for storing liquefied natural gas. Connected to the second storage tank 13 is an upstream end portion of a take-out path 17 through which the liquefied natural gas stored in the filling chamber 13D is taken out and introduced into the evaporator 14.

  The second storage tank 13 is provided with a pressurizing passage 15 for pressurizing the inside of the filling chamber 13D. The pressurizing passage 15 is connected to the bottom of the filling chamber 13D to take out liquefied natural gas. The liquefied natural gas taken out from the pressurizing passage 15 is vaporized by the evaporator 15B. Further, the pressurizing passage 15 is connected to the upper portion of the filling chamber 13D and sends the vaporized natural gas into the gas phase. The pressurizing passage 15 is provided with a pressure adjusting valve 15A for pressurizing the gas phase formed in the upper portion of the filling chamber 13D. By this pressurization, the liquefied natural gas stored in the filling chamber 13D is taken out from the take-out path 17.

  The evaporator 14 vaporizes the liquefied natural gas taken out from the second storage tank 13 and introduced into the natural gas. The evaporator 14 is connected to the upstream end of a gas transfer path 16 that takes out the vaporized natural gas and sends it to the first storage tank 11. The downstream end of the gas transfer path 16 is connected to the gas phase portion above the filling chamber 11D of the first storage tank 11. The gas transfer path 16 is provided with a pressure gauge 16A and a pressure regulating valve 16B. Natural gas is fed into the gas phase portion of the filling chamber 11D of the first storage tank 11 through the gas transfer path 16, and the inside of the filling chamber 11D is pressurized. By this pressurization, the liquefied natural gas stored in the filling chamber 11D is taken out from the supply path 7.

  The evaporator 14 heats and vaporizes the liquefied natural gas, and can use an air heating type or a source using water, hot water, steam, electricity, or the like as a heat source.

  The stop means 2 is provided in the supply path 7 described above. The stopping means 2 includes a pressure detector 2A for detecting the internal pressure in the filling chamber 4D of the on-vehicle tank 4 and a timing at which the pressure detected by the pressure detector 2A suddenly rises, and the supply of the liquefied natural gas by the supplying means 1 And a stop valve 2B for stopping the supply.

  The stopping means 2 starts the supply of the liquefied natural gas by the supply means 1, so that the supply of the liquefied natural gas by the supply means 1 is performed at a timing when the internal pressure of the in-vehicle tank 4 rising from the initial state suddenly increases thereafter. To stop.

[Liquid natural gas filling method]
The liquefied natural gas filling method according to the first embodiment of the present invention can be realized by the above-described apparatus, for example. That is, the liquefied natural gas filling method of the present embodiment includes a supply step that can be realized by the supply unit 1, for example, and a stop step that can be realized by the stop unit 2, for example.

  In the supply step, the liquefied natural gas is supplied from the first storage tank 11 which is a supply source of the liquefied natural gas to the in-vehicle tank 4 which is mounted on the vehicle 3 and stores the liquefied natural gas as the fuel for the vehicle 3. To do.

  That is, in the supplying step, the liquefied natural gas stored in the filling chamber 11D of the first storage tank 11 is supplied to the filling chamber 4D of the in-vehicle tank 4 through the supply path 7. At this time, the internal pressure of the filling chamber 11 </ b> D of the first storage tank 11 is pressurized by the pressurizing unit 12.

  The pressurizing unit 12 vaporizes the liquefied natural gas stored in the filling chamber 13 </ b> D of the second storage tank 13 with the evaporator 14, and sends it into the filling chamber 11 </ b> D of the first storage tank 11 through the gas transfer path 16. At this time, the natural gas vaporized by the evaporator 14 is adjusted to a predetermined pressure by the pressure adjusting valve 16B. As a result, the internal pressure of the filling chamber 11D of the first storage tank 11 is increased, and the liquefied natural gas stored in the filling chamber 11D of the first storage tank 11 is taken out from the supply path 7 and the filling chamber 4D of the in-vehicle tank 4 is filled. To be supplied.

  A part of the liquefied natural gas stored in the filling chamber 13D of the second storage tank 13 is vaporized when passing through the pressurizing passage 15, and is sent to the gas phase of the filling chamber 11D. At this time, the natural gas evaporated in the pressurizing passage 15 is adjusted to a predetermined pressure by the pressure adjusting valve 15A. Thereby, the internal pressure of the filling chamber 13D of the second storage tank 13 is increased, and the liquefied natural gas stored in the filling chamber 13D of the second storage tank 13 is taken out from the take-out path 17 and sent to the evaporator 14.

  In the stop step, the supply of the liquefied natural gas in the supply step is stopped at a timing when the internal pressure of the in-vehicle tank 4 rising from the initial state suddenly increases after the start of the supply step.

  That is, when the supply step is started, liquefied natural gas flows into the filling chamber 4D of the on-vehicle tank 4. Thereby, the internal pressure of the said vehicle-mounted tank 4 rises a little from an initial state. While the liquefied natural gas continues to flow into the filling chamber 4D of the on-vehicle tank 4, the internal pressure of the on-vehicle tank 4 is at a level slightly increased from the initial state and changes almost stably. When the filling chamber 4D is filled with the liquefied natural gas, the liquefied natural gas does not flow into the filling chamber 4D any more. On the other hand, the liquefied natural gas in the supply path 7 is continuously pressurized by the supply means 1. For this reason, the internal pressure of the filling chamber 4D increases rapidly. At this time, the rapid increase in the internal pressure of the filling chamber 4D is detected by the pressure detector 2A, and the supply of the liquefied natural gas by the supply means 1 is stopped by closing the stop valve 2B.

  The initial state is preferably a low pressure state in which the internal pressure of the filling chamber 4D of the in-vehicle tank 4 is 0.6 MPa or less, and a low temperature state in which the temperature in the filling chamber 4D of the in-vehicle tank 4 is −120 ° C. or less.

  The operation of setting the state of the filling chamber 4D of the in-vehicle tank 4 in this way to the initial state can be omitted if low-temperature liquefied natural gas remains in the filling chamber 4D. However, for example, in the vehicle 3 in which the liquefied natural gas in the in-vehicle tank 4 is left empty for several days or more, the liquefied natural gas in the in-vehicle tank 4 is vaporized by heat entering from the outside, and the in-vehicle tank 4 The inside is in a high pressure and high temperature state. Even if the supply of the liquefied natural gas is started as it is, a sufficient amount of the liquefied natural gas cannot be filled. Therefore, an operation for setting the filling chamber 4D of the in-vehicle tank 4 to the initial state is required.

  That is, if the filling chamber 4D is at a pressure exceeding the pressure, a sufficient amount of liquefied natural gas cannot be filled even if the supply of liquefied natural gas is started therefrom. Similarly, even if the filling chamber 4D is at a temperature exceeding the above temperature, a sufficient amount of liquefied natural gas cannot be filled even if the supply of liquefied natural gas is started from there. Therefore, by setting the initial state to the low-pressure state and the low-temperature state described above, a sufficient amount of liquefied natural gas can be charged when the supply of liquefied natural gas is started from there.

  Before starting the supply step, it is preferable that the in-vehicle tank 4 is brought into the low-pressure state by venting the gas in the in-vehicle tank 4. The operation to make the low pressure state can lower the internal pressure of the filling chamber 4D by opening the discharge valve 8A and extracting the gas in the filling chamber 4D of the in-vehicle tank 4 from the gas discharge path 8. By this degassing operation, the internal pressure of the filling chamber 4D decreases.

  Before starting the supplying step, it is preferable to introduce the liquefied natural gas into the vehicle tank 4 to bring the vehicle tank 4 into the low temperature state. The operation to make the low temperature state can be performed by introducing liquefied natural gas from the supply means 1 into the filling chamber 4D of the in-vehicle tank 4 and cooling the filling chamber 4D with the low temperature liquefied gas. By this cooling operation, the gas filled in the filling chamber 4D is cooled and liquefied, and the internal pressure of the filling chamber 4D also decreases.

  Either the above-described operation of extracting the gas from the filling chamber 4D or the operation of introducing and cooling the liquefied natural gas into the filling chamber 4D may be performed depending on the situation. For example, when the inside of the filling chamber 4D is in a low temperature state of −120 ° C. or lower and the internal pressure exceeds 0.6 MPa, it is sufficient to perform an operation of extracting the gas from the filling chamber 4D. Further, when the internal pressure of the filling chamber 4D is a low pressure state of 0.6 MPa or less and the temperature exceeds −120 ° C., an operation of introducing liquefied natural gas into the filling chamber 4D and cooling it is sufficient. Even in these cases, it is possible to perform both the operation of degassing and the operation of cooling simultaneously, or these can be performed continuously.

[Effect of the embodiment]
This embodiment has the following effects.

  In the present embodiment, the liquefied natural gas is supplied from a liquefied natural gas supply source to an in-vehicle tank 4 that is mounted on the vehicle 3 and stores liquefied natural gas as fuel for the vehicle 3. From the initial stage to the middle stage of the supply, liquefied natural gas flows into the in-vehicle tank 4 at a stable pace, and the amount of liquid in the in-vehicle tank 4 continues to increase. At this time, the internal pressure of the in-vehicle tank 4 is slightly increased from the initial state. When the in-vehicle tank 4 is filled with liquefied natural gas, the liquefied natural gas no longer flows into the in-vehicle tank 4. On the other hand, since the liquefied natural gas that is the supply source of the liquefied natural gas tends to move into the in-vehicle tank 4, the internal pressure of the in-vehicle tank 4 rapidly increases. At this timing, the stopping means 2 stops the supply of liquefied natural gas in the supplying step by the supplying means 1. The inside of the on-vehicle tank 4 is filled with liquefied natural gas. In this way, when the liquefied natural gas is filled in the in-vehicle tank 4 of the liquefied natural gas vehicle 3, the end point of filling can be detected accurately and easily.

  In the present embodiment, the initial state is specified. That is, the initial state is a low pressure state in which the internal pressure in the in-vehicle tank 4 is 0.6 MPa or less, and a low temperature state in which the temperature in the in-vehicle tank 4 is −120 ° C. or less. If the inside of the in-vehicle tank 4 is in the low pressure state and the low temperature state, the in-vehicle tank 4 is in a state of accepting the supply of liquefied natural gas. In other words, if the internal pressure of the in-vehicle tank 4 is high, the internal pressure of the in-vehicle tank 4 rapidly increases even if liquefied natural gas is supplied from there, and the in-vehicle tank 4 cannot be filled with a sufficient amount of liquefied natural gas. Moreover, even if the temperature in the on-vehicle tank 4 is high, even if liquefied natural gas is supplied from there, the internal pressure of the on-vehicle tank 4 increases rapidly, and the in-vehicle tank 4 is filled with a sufficient amount of liquefied natural gas. Can not. Therefore, if the initial state of the in-vehicle tank 4 is the low pressure state and the low temperature state, a sufficient amount of liquefied natural gas can be filled from the in-vehicle tank 4 through the supply of liquefied natural gas. It is.

  This embodiment specifies the step which makes the said vehicle-mounted tank 4 an initial state before starting the said supply step. That is, when the vehicle-mounted tank 4 is in the low temperature state, the vehicle-mounted tank 4 is brought into the low-pressure state by venting the gas in the vehicle-mounted tank 4 before starting the supply step. Thereby, the said supply step is started after the said vehicle-mounted tank 4 is reliably made into an initial state. From there, a sufficient amount of liquefied natural gas can be filled into the in-vehicle tank 4 through the supply of liquefied natural gas.

  This embodiment specifies the step which makes the said vehicle-mounted tank 4 an initial state before starting the said supply step. That is, when the in-vehicle tank 4 is in the low pressure state, the in-vehicle tank 4 is brought into the low temperature state by introducing liquefied natural gas into the in-vehicle tank 4 before starting the supply step. Thereby, the said supply step is started after the said vehicle-mounted tank 4 is reliably made into an initial state. From there, a sufficient amount of liquefied natural gas can be filled into the in-vehicle tank 4 through the supply of liquefied natural gas.

In the present embodiment, a specific structure of the on-vehicle tank 4 is specified. That is, the on-board tank 4 includes a filling chamber 4D filled with the liquefied natural gas by the supplying step, and a spare chamber 4E partitioned from the filling chamber 4D by a partition wall 4G with a communication path 4F. .
In the storage of fuel-based liquefied gas such as liquefied natural gas, the danger increases if the in-vehicle tank 4 is completely filled with the full capacity. For example, liquefied gas is vaporized by the outside air temperature, the internal pressure rises, and there is a risk of explosion. There is also a risk of fire from fuel gas. Therefore, in order to prevent an accident due to full filling, a spare chamber 4E is provided inside the in-vehicle tank 4.

At this time, the capacity of the spare chamber 4E is preferably set to 10% by volume ± 5% by volume of the capacity of the entire vehicle tank 4. In other words, the user of liquefied natural gas wants to fill the on-board tank 4 with as much liquefied natural gas as possible. If the capacity of the spare chamber 4E is set to 10 volume% ± 5 volume% of the capacity of the entire vehicle tank 4, the capacity of the spare chamber 4E from the capacity of the vehicle tank 4 (10 volume% ± 5 volume% of the entire vehicle tank 4) The above supply step is stopped when as much of the liquefied natural gas as possible is filled up to the upper limit of the capacity of the filling chamber 4D excluding the above (90 volume% to 5 volume% of the entire vehicle tank 4). As a result, the upper limit of liquefied natural gas can be filled within a range in which safety is ensured.

  FIG. 2 is a diagram for explaining the test apparatus of the embodiment.

  In this test apparatus, the vehicle-mounted tank 4 is not mounted on the vehicle 3 but is placed on the first mass meter 21 and its mass is measured. Moreover, the 1st storage tank 11 is mounted in the 2nd mass meter 22, and the mass is measured. Other than that, the configuration is the same as in FIG. 1, and the same reference numerals are given to the same portions, and descriptions thereof are omitted.

  In this test apparatus, a tank having a capacity of 176 L was used as the first storage tank 11, and a tank having a capacity of 131 L was used as the in-vehicle tank 4. In this test, liquefied natural gas was replaced with liquefied nitrogen, and a filling test was conducted in a state where safety was ensured. Moreover, in this test, the mass decrease of the 1st storage tank 11 and the mass increase of the vehicle-mounted tank 4 were measured, and it confirmed that the filling end point in the vehicle-mounted tank 4 was supported from the surface of mass change.

〔Test procedure〕
1) defines the amount of LN ₂ to the first storage tank 11 (about 119Kg) filled. The pressure regulating valve 15A is opened, the internal pressure of the filling chamber 13D is increased to about 1.6 MPa, and the pressure regulating valve 15A is closed.
2) The empty mass of the first storage tank 11 used for the test is measured with the second mass meter 22. Specified amount of LN ₂ to the first storage tank 11 (about 119Kg) filled.
3) The in-vehicle tank 4 is mounted on the first mass meter 21. In this state, gas is discharged from the discharge valve 8A while GN ₂ and LN ₂ are supplied to the filling chamber 4D from a container (not shown) separate from the first storage tank 11, and the filling chamber 4D is cooled. . At this time, cooling is performed while confirming that the display value of the first mass meter 21 does not change. That is, cooling is performed at a level that does not cause liquefied natural gas to accumulate in the filling chamber 4D. As a guide, cooling is performed until the gas temperature discharged from the discharge valve 8A reaches about −100 ° C. After cooling, the pressure in the filling chamber 4D is lowered to 0.5 MPa.
4) The supply of liquefied natural gas from the first storage tank 11 to the in-vehicle tank 4 is started. The open / closed state of the valves V1 to V5 at this time is shown in Table 1 below. V5 is a stop valve 2B. 5) The pressure detected by the pressure detector 2A and the mass measured by the first mass meter 21 were plotted.

[Case 1]
In Case 1, liquefied natural gas was filled into the on-vehicle tank 4 having a filling rate of 0% by volume.
FIG. 3 is a diagram in which the pressure in the filling chamber 4D measured by the pressure detector 2A (lower line) and the mass of the in-vehicle tank 4 measured by the first mass meter 21 (upper line) are plotted.
Table 2 summarizes the mass of the in-vehicle tank 4 measured with the first mass meter 21 into the filling amount and the mass of the first storage tank 11 measured with the second mass meter 22 into the supply amount. is there.

  As can be seen from FIG. 3, the pressure in the in-vehicle tank 4 that had been changing at about 0.3 to 0.4 MPa after the start of filling suddenly increases to 0.65 MPa at a stroke in about 6 minutes after the start of filling. . Filling is started from the state where the filling rate of the on-vehicle tank 4 is 0%, and when the pressure reaches 77.4% by volume, the pressure rises rapidly. Shortly thereafter, pressure fluctuations reached in parallel. At this time, the filling rate was 80.4%, which was the filling end point of the on-vehicle tank 4.

From this result, when the liquefied natural gas is actually filled in the in-vehicle tank 4, the filling end point of the in-vehicle tank 4 can be detected as follows.
(1) The in-vehicle tank 4 is empty (filling rate 0%), and the filling chamber 4D is sufficiently pre-cooled.
(2) Open the V4 valve and start supplying the liquefied natural gas to the in-vehicle tank 4.
(3) A change in pressure at the pressure detector 2A is observed. Here, the point of time when the pressure rapidly increases and then reaches parallel is the end point of filling. That is, it becomes the filling rate of the vehicle-mounted tank 4 which can be satisfied at this time.

[Case 2]
In Case 2, an in-vehicle tank 4 having a filling rate of 37% was prepared, and a test for starting filling was performed from here. That is, it is a case where filling is started from a state in which some liquefied natural gas remains in the in-vehicle tank 4.
FIG. 4 is a diagram in which the pressure in the filling chamber 4D measured by the pressure detector 2A (a line starting from the lower side) and the mass of the vehicle-mounted tank 4 measured by the first mass meter 21 (a line starting from the upper side) are plotted. is there.
Table 3 summarizes the mass of the in-vehicle tank 4 measured with the first mass meter 21 into the filling amount and the mass of the first storage tank 11 measured with the second mass meter 22 into the supply amount. is there.

  As can be seen from FIG. 4, the pressure in the in-vehicle tank 4 that had been changing at about 0.3 to 0.4 MPa after the start of filling suddenly increased to about 1.2 MPa at a stroke in about 4 minutes after the start of filling. Yes. In Case 2, the LNG container started filling from a state where the filling ratio was 37%, and when the pressure reached 81.8%, a rapid pressure increase was observed. Shortly thereafter, pressure fluctuations reached parallel. At this point, the filling amount was 84.3%, which was the filling end point of the main body container.

From this result, when the LNG is actually filled into the in-vehicle tank 4 with the liquefied natural gas remaining as in the case 2, the end point of the filling can be detected as follows.
(1) The liquefied natural gas remains in the in-vehicle tank 4, and the filling chamber 4D has already been pre-cooled.
(2) Open the V4 valve and start supplying the liquefied natural gas to the in-vehicle tank 4.
(3) A change in pressure at the pressure detector 2A is observed. Here, the point of time when the pressure rapidly increases and then reaches parallel is the end point of filling. That is, it becomes the filling rate of the vehicle-mounted tank 4 which can be satisfied at this time.

In both cases 1 and 2, the difference in the filling amount was approximately constant at about 3% from when the pressure in the filling chamber 4D started to rise rapidly until the end of filling.
Therefore, if the pressure change is detected by the pressure detector 2A, the filling amount reaches 80 to 84% when the pressure in the filling chamber 4D, which has been changing at about 0.3 to 0.4 MPa, starts to rise rapidly. It was. At this first time, the filling rate does not exceed 90%. This can be the end point of filling. Further, at the second time point that reaches in parallel, it is possible to fill up to a value closer to 90%.

The following can be understood from the test results of the examples.
In a liquefied natural gas vehicle equipped with an on-vehicle tank 4 having a spare chamber 4E as a fuel tank, the pressure change in the filling chamber 4D in the pressure detector 2A is measured in order to detect the end point of filling of the liquefied natural gas. If the supply is stopped when the pressure suddenly increases, the vehicle tank 4 can be filled with 80% or more of its capacity. After that, if the supply is stopped at the time of reaching in parallel, more can be filled.
Thereby, the liquefied natural gas can be filled to an appropriate filling amount. That is, it can be filled as much as possible within 90% of the capacity of the in-vehicle tank 4.

Thus, in the present invention, the “timing at which the internal pressure of the tank that rises from the initial state suddenly rises thereafter” includes the following two time points.
First, it is a point in time when the pressure in the filling chamber 4D that has been changing at about 0.3 to 0.4 MPa suddenly increases.
Second, it is a point in time when the pressure in the filling chamber 4D that has rapidly increased reaches in parallel.

[Modification]
The above has described a particularly preferred embodiment of the present invention. However, the present invention is not intended to be limited to the illustrated embodiment, and can be implemented by being modified in various aspects, and the present invention includes various modifications. This is the purpose.

1: Supply means 2: Stop means 2A: Pressure detector 2B: Stop valve 3: Vehicle 4: Vehicle tank 4A: Inner tank 4B: Outer tank 4C: Vacuum insulation layer 4D: Filling chamber 4E: Preliminary chamber 4F: Communication path 4G : Partition wall 5: engine unit 6: evaporator 7: supply path 8: gas discharge path 8A: discharge valve 11: first storage tank 11A: inner tank 11B: outer tank 11C: vacuum heat insulating layer 11D: filling chamber 12: pressurization Unit 13: Second storage tank 13A: Inner tank 13B: Outer tank 13C: Vacuum heat insulating layer 13D: Filling chamber 14: Evaporator 15: Pressurization path 15A: Pressure adjustment valve 15B: Evaporator 16: Gas transfer path 16A: Pressure Total 16B: Pressure regulating valve 17: Extraction path 21: First mass meter 22: Second mass meter

Claims (6)

A supply step of supplying the liquefied natural gas from a supply source of liquefied natural gas to a tank that is mounted on a vehicle and stores liquefied natural gas as fuel for the vehicle;
Filling with liquefied natural gas, comprising: a stop step of stopping the supply of liquefied natural gas in the supply step at a timing when the internal pressure of the tank rising from the initial state suddenly increases after the start of the supply step Method. The liquefied natural gas filling method according to claim 1, wherein the initial state is an internal pressure of 0.6 MPa or less and a temperature of −120 ° C. or less in the tank. The liquefied natural gas filling method according to claim 2, wherein the inside of the tank is brought into the low pressure state by extracting the gas from the tank before the supply step is started. The liquefied natural gas filling method according to claim 2 or 3, wherein the liquefied natural gas is introduced into the tank before the supply step is started to bring the tank into the low temperature state. The said tank is provided with the filling chamber filled with the said liquefied natural gas by the said supply step, and the reserve chamber partitioned off from the said filling chamber by the partition with a communicating path. The liquefied natural gas filling method according to the item. Supply means for supplying the liquefied natural gas from a liquefied natural gas supply source to a tank that is mounted on a vehicle and stores the liquefied natural gas as fuel for the vehicle,
And a stop means for stopping the supply of the liquefied natural gas by the supply means at a timing when the internal pressure of the tank rising from the initial state suddenly increases after the supply means starts supplying the liquefied natural gas. A liquefied natural gas filling device characterized by

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