System for draining and refilling cryogenic fuel in a vehicle tank

Abstract

A tool for draining and refilling a vehicle tank for cryogenic fuel, wherein the tool when in position for use has a vertical direction and includes a heat exchanger and a cooling tank, the cooling tank having an upper portion and a lower portion as viewed in the vertical direction of the tool and including a fuel outlet having at least one outlet valve, the fuel outlet being connected to a first fuel conduit and second fuel conduit via the at least one outlet valve, wherein the first fuel conduit includes an arrangement for connecting the first fuel conduit to an inlet on the heat exchanger, and wherein the second fuel conduit includes an arrangement for connecting the second fuel conduit to an inlet on a vehicle tank, the cooling tank further including an inlet, the inlet being connected to a fuel inlet conduit via a check valve and the fuel inlet conduit including an arrangement for connecting the inlet to an outlet from the heat exchanger, or to an outlet from a vehicle tank, and the outlet of the heat exchanger including an arrangement for connecting to an inlet on a vehicle tank, and a system and method for draining and refilling a vehicle tank.

Claims

1. A tool for draining and refilling a vehicle tank for cryogenic fuel, wherein the tool when in position for use has a vertical direction and comprises a heat exchanger and a cooling tank, the cooling tank having an upper portion and a lower portion as viewed in the vertical direction of the tool and comprising a fuel outlet on the cooling tank having at least one outlet valve, the fuel outlet on the cooling tank being connected to a fuel outlet conduit, wherein the fuel outlet conduit comprises a first connector for connecting the fuel outlet on the cooling tank to an inlet on the heat exchanger, and wherein the fuel outlet conduit comprises a second connector for connecting the fuel outlet on the cooling tank to an inlet on the vehicle tank, and the cooling tank further comprises a cooling tank inlet, the cooling tank inlet being connected to a fuel inlet conduit via a check valve, and the fuel inlet conduit comprises a third connector for connecting the cooling tank inlet to an outlet of the heat exchanger, or to an outlet of the vehicle tank, and the outlet of the heat exchanger comprises a fourth connector for connecting to the inlet on the vehicle tank, wherein the heat exchanger is provided with a fifth connector for connecting the inlet on the heat exchanger to a fuel outlet on the vehicle tank such that the cryogenic fuel from the vehicle tank can be conducted to said heat exchanger and returned to the vehicle tank.

2. The tool according to claim 1, wherein the at least one outlet valve is disposed on the fuel outlet conduit, and wherein the fuel outlet conduit divides into a first fuel conduit and a second fuel conduit downstream of the at least one outlet valve, as viewed in a direction from the fuel outlet on the cooling tank.

3. The tool according to claim 1, wherein the check valve is adapted to open at a back pressure from the cooling tank from 12 to 24 bars.

4. The tool according to claim 1, wherein the cooling tank inlet to the cooling tank is placed above the fuel outlet from the cooling tank in the vertical direction of the tool.

5. The tool according to claim 3, wherein a spraying device is connected to the cooling tank inlet of the cooling tank inside the cooling tank, the spraying device being adapted for spraying the cryogenic fuel into the upper portion of the cooling tank.

6. The tool according to claim 1, wherein a gas outlet is disposed in the upper portion of the cooling tank.

7. The tool according to claim 6, wherein the gas outlet is connected via one or several valves to one or several gas outlet conduits.

8. The tool according to claim 6, wherein one gas outlet conduit is provided with a safety valve, which is adapted to open automatically at an outlet pressure of 24 bars.

9. The tool according to claim 6, wherein one gas outlet conduit is provided with an outlet valve, which is adapted to be opened and closed manually.

10. The tool according to claim 1, wherein the tool is portable.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) In the following, the invention will be described more closely with reference to the attached drawings. In the figures, identical or similar details are indicated with the same reference numerals. The figures are only schematic representations and are not intended to show exact details of the invention. The flames are solely intended to illustrate typical embodiments of the invention, and should therefore not be regarded as limiting for the invention.

(2) FIG. 1 shows a schematic view of a tool according to the invention.

(3) FIG. 2 shows a schematic view of a system according to the invention. In the figure, the system is shown in a draining mode.

(4) FIG. 3 shows a schematic view of a system according to the invention. In the figure, the system is shown in a refilling mode.

DETAILED DESCRIPTION

(5) FIG. 1 shows a tool 100 for draining and refilling a vehicle tank 15 for cryogenic fuel 33, wherein the tool 100 comprises a heat exchanger 13 and a cooling tank 1, said cooling tank 1 exhibiting an outlet 35 to a fuel outlet conduit 35 having at least one outlet valve 2, said fuel outlet 35 being connectable to a first fuel conduit and a second fuel conduit via the outlet valve 2 and a connecting device 3. The cooling tank 1 comprises a fuel inlet 38, which is connected to a fuel inlet conduit 39 via a check valve 4. The fuel inlet conduit 39 exhibits a connecting device 5 for connecting the fuel inlet 38 in the shown draining mode. In this mode, the fuel conduit 40 is connected to the heat exchanger 13 via a connecting means 28. The fuel conduit 40 is also adapted for connecting to the inlet 38 of the cooling tank 1 via a connecting means 5.

(6) Fuel which is passed into one of the tanks 1, 15 is injected into the upper portion of the tank, for example by means of a spraying device 50 having a plurality of spraying orifices disposed along a conduit extending into the tank, to obtain a rapid cooling of the walls of tank. Accordingly, this means that there is fuel both in liquid form 33 and in vapour form 34 in the tanks. The outlet conduit 41 is connectable via a throttle valve 16 to the inlet conduit 39 via a connecting means 5 and via a throttle valve 32 to the fuel conduit 45, which via a connecting means 27 is connected to the inlet of the heat exchanger 13.

(7) Accordingly, fuel is suitably injected into the cooling tank 1, the spraying device 50 is connected to the inlet 38 of the cooling tank for gaseous fuel inside the cooling tank 1, and the spraying device is thus adapted to spray fuel into the upper portion of the cooling tank 1.

(8) Accordingly, in the tool 100, the heat exchanger 13 is provided with means 27 for connecting the inlet of the heat exchanger 13 to an outlet 41 for liquid fuel on a vehicle tank 15. A gas outlet 44 from the cooling tank 1 leads to a safety system for release of excess gas and is connected to one or several gas outlet conduits 44 via suitable valves and connecting devices, as is shown in the figures and is described herein.

(9) As is shown in the figures, the outlet device 2, in the tool 100, can be disposed on a fuel outlet conduit 35 for liquid fuel from the cooling tank 1, wherein the fuel outlet conduit 35 divides into said first fuel conduit and said second fuel conduit downstream of the outlet valve 2, as viewed in the direction from the outlet 35 in the cooling tank 1.

(10) As is shown in the figures, the gas outlet conduits are provided with safety valves, which are adapted to open automatically at an outlet pressure of 24 bars.

(11) The gas outlet conduits are also provided with throttle valves 2, 16, which are adapted to be opened and closed manually.

(12) The gas outlet 44 is disposed in the upper portion of the cooling tank 1, as is shown in FIG. 1. In a corresponding way, an outlet 42 for gaseous fuel is disposed in the upper portion of the vehicle tank 15 and leads to a safety system for discharge of excess gas. The gas outlet 44 in the cooling tank is via a conduit provided with a throttle valve 8 and a relief valve 9 to a discharge opening 12. Another conduit, which is connected to the outlet 44, exhibits a relief valve 11 connected to a valve pipe 10, and an additional pipe connected to the gas outlet 44 is connected to a safety valve 6 and to a pressure gauge 7.

(13) In a corresponding way, in the vehicle tank there is seen an outlet 42 connected via a conduit to a relief valve 24 and to an admission pipe 23 to reach to an outlet opening 14, and furthermore a conduit connected to the outlet 42 and to a pressure gauge 20 and also a safety valve 29.

(14) In FIG. 2, the system of FIG. 1 is illustrated configured for draining the vehicle tank 15 of cryogenic fuel 33. The system is based on what has been described in FIG. 1 above. In order to drain the fuel tank 15 of fuel 33, the conduits are connected such that draining is enabled. The basic idea is that fuel 33 in the vehicle tank 15 is conducted to the heat exchanger 13, wherein the fuel 33 is transformed into gaseous form 34 and is returned to the vehicle tank 15, which is thereby pressurized. The increased pressure enables transfer of fuel 33 from the vehicle tank 15 to the cooling tank 1 via the fuel conduit 37. In order to enable the system to operate in a draining mode, the fuel inlet 38 on the cooling tank 1 is connected to the fuel inlet conduit 39 via the connecting means 5 to the fuel conduit 37, which in its turn is connected to the outlet conduit 41 from the vehicle tank 15 via a connecting means 17. Furthermore, the outlet conduit 41 is via the connecting means 27, 31 connected via a fuel conduit 45 to the heat exchanger 13, and via the connecting means 28, 19 and a fuel conduit 40 to an inlet 43 via a cheek valve 18. The outlet conduit 41 is connectable to the inlet conduit 39 via a throttle valve 16 and to the fuel conduit 45 via a throttle valve 32, which via connecting means 27 is connected to the inlet of the heat exchanger 13. By means of these connections, liquid cryogenic fuel 33 can be passed from the vehicle tank 15 through the fuel conduit 37 to the cooling tank 1 by the pressure increase caused by the vaporization in the heat exchanger 13 and by a portion of the fuel 33 being returned from the vehicle tank 15 via the heat exchanger 13 in gaseous form and injected into the vehicle tank 15 via the inlet 43 of the vehicle tank. Moreover, the inlet 43 is also the inlet for the normal refuelling of the vehicle.

(15) The inlet 38 to the cooling tank 1 is placed above the fuel outlet 35 of the cooling tank in the vertical direction of the tool, and, as previously mentioned, there is a spraying device 50 spraying the fuel into the cooling tank 1.

(16) The cooling tank can have various shapes, such as cylindrical or rectangular, and it can be horizontal or vertical and may assume different volumes. A cooling tank can be in the size range between, for example, 100-1200 litres, wherein 450 litres-498 litres is a preferred size and 600 litres is a particularly preferred size. The tank is suitably insulated, for example with polyurethane foam, to be able to maintain the low temperature.

(17) Accordingly, the heat exchanger 13 is adapted to transform liquid fuel 33 into gas, which gas when transferred to the vehicle tank 15 expands while creating pressure in the vehicle tank 15, and thereby enables expulsion of fuel in liquid form 33 from the vehicle tank 15 to the cooling tank 1 through the fuel conduit 37. It is thus the pressure resulting from the liquid being transformed into gaseous form in the heat exchanger 13 which enables a transfer of liquid between the tanks. The pressure liar achieving a good expulsion of fuel has been found to be about 4-7 bars of normal working pressure.

(18) In FIG. 3, the herein described tool and system for draining and refilling a vehicle tank 15 is illustrated in a condition where fuel is returned from the tool 100 to the vehicle tank. In broad outline, in the condition for returning fuel to the vehicle tank 15, the heat exchanger 13 is connected to the cooling tank 1 via a fuel conduit 45 and liquid fuel 33 is taken from the cooling tank 1, is vaporized in the heat exchanger 13, and the vaporized fuel 34 is then returned to the cooling tank 1 via a fuel conduit 40 for increasing the pressure in the cooling tank 1. In more detail, the outlet 35 on the cooling tank 1 is connected to an outlet valve 2 for connecting the fuel conduit 37 via the connecting means 3. The fuel conduit 37, in its turn, is connected via a connecting means 19 and a check valve 18 to the inlet 43 of the vehicle tank 1 for the injection of fuel 34 into the vehicle tank 15. The outlet 35 from the cooling tank 1 is further connected via the outlet valve 2 and a throttle valve 25 to the fuel conduit 45 via a connecting means 26. This fuel conduit 45 transports liquid fuel 33 to the heat exchanger 13 via a connecting means 27 to the heat exchanger 13, wherein the fuel 33 is vaporized during passage through the heat exchanger 13 and is passed via a connecting means 28 mounted to the heat exchanger 13 to a conduit 40 for the now gaseous fuel 34. The conduit 40 is connected to the inlet 38 of the cooling tank via the connecting means 5 and the check valve 4. Accordingly, the heat exchanger 13 transfers fuel in gaseous form to the cooling tank 1 wherein a pressure is produced therein, which enables fuel to be expelled back from the cooling tank 1 to the vehicle tank 15. Accordingly, since the pressure in the cooling tank 1 is increased, fuel 33 is forced from the cooling tank 1 to the vehicle tank 15 through the fuel conduit 37 between the cooling tank 1 and the vehicle tank 15. The check valve 4 is adapted to open at a back pressure from the cooling tank 1 of from 12 to 24 bars, such as from 14 to 18 bars, preferably at a back pressure from the cooling tank 1 of 16 bars.

(19) Suitably, both the cooling tank 1 and the vehicle tank 15 are grounded to prevent spark formation.

(20) In order to further explain the invention, it is seen as a method for draining and refilling cryogenic fuel 33, 34 in a vehicle tank 15. The method comprises a plurality of steps, and can more specifically be described as a method for draining cryogenic fuel from a vehicle tank 15 for cryogenic fuel, wherein the method comprises the following steps:

(21) A) providing a tool of the herein described kind comprising a cooling tank 1 and a heat exchanger 13;

(22) B) forming a system of the herein described kind by connecting the tool to a vehicle tank 15, wherein one of the vehicle tank 15 and the cooling tank 1 of the tool constitutes a supplying tank containing cryogenic, pressurized fuel 33 for transfer to the other one of the vehicle tank 15 and the cooling tank 1 of the tool, which thereby constitutes a receiving tank;

(23) C) transforming liquid cryogenic fuel 33 into gaseous form 34 by causing the liquid fuel 33 to pass through the heat exchanger 13 of the tool;

(24) D) developing an expelling pressure in the supplying tank 1, 15 by injecting the fuel 33 transformed in the heat exchanger 13; and

(25) E) transferring fuel 33 from the supplying tank to the receiving tank, wherein the increased pressure in the supplying tank drives the transfer of fuel from the supplying tank the receiving tank.

(26) In the above-described method, the vehicle tank can be the supplying tank and the liquid cryogenic fuel in step C) is taken from the vehicle tank via an outlet on the vehicle tank.

(27) Alternatively, it can be the case that the vehicle tank is the supplying tank and the cooling tank of the tool is filled with a small amount of liquid cryogenic fuel, wherein the liquid cryogenic fuel in step C) is taken from the cooling tank of the tool via an outlet on the cooling tank of the tool.

(28) The cooling tank of the tool can also the supplying tank and the liquid cryogenic fuel in step C) can be taken from the cooling tank of the tool via an outlet on the vehicle tank.

(29) The working pressure in the supplying tank can be from 2 to 7 bars, such as from 3 to 5 bars, or 3 bars, and the pressure in the receiving tank is at least 1 bar lower than the pressure in the supplying tank, such as at least 2 bars lower than the pressure in the supplying tank.

(30) The switching from draining mode to refilling mode can, purely mechanically, be described as if some fuel conduits are switching their respective connecting means. This can be illustrated in that:

(31) The fuel conduit 37 is switched from connecting means 17 to 19.

(32) The fuel conduit 45 is switched from connecting means 31 to 26.

(33) The fuel conduit 40 is switched from connecting means 19 to 5.

(34) The fuel is sprayed into the cooling tank 1, since the fuel in atomized form cools the tank. In order to maintain a sufficiently low temperature of, for example, about 160 degrees Celsius, of the cryogenic fuel 33, 34 in the system, the conduits are made of materials which can withstand the relative heat in the surroundings. The connections between the inlet, outlet and valves of the cooling tank 1 and the vehicle tank 15 are constituted by components which can be insulated.

(35) As described above, the overpressure may have to be regulated if the temperature is raised so that the fuel 33 is transformed into gaseous fuel 34. The pressure can also be raised in the cooling tank 1 if a larger amount of liquid fuel 33 is supplied to the tank 1 than it can hold. To enable fuel 33 to be introduced from the vehicle tank 15, a corresponding amount has to be tapped from the tank at a steady rate. If the steady rate is disrupted, an overpressure may develop in the cooling tank 1. As is shown in the figures, the cooling tank 1 also comprises a valve 9 connected to the gas outlet 44 for regulating the overpressure from gaseous fuel 34.

(36) The gas 34 vented through the valve 9 is usually released into the surroundings, but, alternatively, it can also be burned off.

(37) In the figures, a plurality of valves of different kinds can be seen. The valves can be designed to be capable of receiving and forwarding fuel both in liquid form 33 and in gaseous form 34. It is also possible that some of the valves are designed for allowing passage of fuel 33, 34 in both of their directions. In another variant, different types of valves, one for the lower valves and one for the upper valves, are used. In the upper valves in the figures, gas is to be passed into the tanks, and through the lower valves, fuel in liquid form is passed out of the two tanks. The valve 8 is a throttle valve of manual type having an on/off position. Furthermore, the valve connections are adapted to enable injection of the gas into the tanks.

(38) The connecting means 5 in connection with the cooling tank 1 and 19 in connection with the vehicle tank 15 are constituted by refilling valves to enable refilling of the tanks, whereas the valve 11 is constituted by a relief valve, which is opened and closed automatically at, for example, 16 bars.

(39) The valves 6, 29 and 30 are constituted by safety valves, which are only pressure controlled and open when the system is used, whereas the valves 11 and 24 are relief valves.

(40) To facilitate the work, the tool including the cooling tank 1 can be portable and movable, possibly by a pallet lifter. Preferably, the cooling tank is not larger than about 500 dm3, preferably 498 dm3, to enable it to be handled as desired. In some applications, it may be an advantage to divide the tank into two sub-tanks. To enable handling in the manner described above, the cooling tank suitably can have pallet-size base dimensions.

(41) To further facilitate the process, one possibility is that the portable cooling tank is seen as part of the commercial vehicle. In that case, the portable cooling tank 1 can be attachable to the vehicle associated with the vehicle tank 15.

(42) As a rule, the use of the cooling tank can be encouraged before servicing the vehicle. This is simplified if the cooling tank is easy to manage and easy to handle from an ergonomic point of view. It is also favourable if the cooling tank is stored in a suitable location. Therefore, the cooling tank could be located in a workshop, suitable for use in shop work.

(43) Compressed Natural Gas (CNG) produces relatively few undesirable fumes and is also a comparatively safe fuel, since the gas weighs less than air and is dispersed rapidly by ventilation. CNG is usually stored in containers at a pressure of 200 to 248 bars. Owing to the above-mentioned properties, CNG is suited for use as fuel in a vehicle tank 15. Furthermore, it is possible to transfer CNG to a cooling tank 1 in the system according to the invention. The fuel in gaseous form can therefore be CNG in the above-described system for draining and refilling a vehicle tank 15.

(44) Furthermore, in FIG. 3, it is seen that the cooling tank 1 has a predetermined, fixed shape. Thereby, also the amount of fuel in the tank can be determined. Furthermore, the cooling tank 1 can contain a predefined amount of fuel (LNG).

(45) As previously mentioned, CNG is a gas which in liquid form turns into Liquefied Natural Gas (LNG).

(46) Furthermore, at least one additional cooling tank can be used. In some situations, it may be advantageous to have two or more cooling tanks, for example when there is an unexpectedly large amount of fuel left in the tank, which is to be transferred to the cooling tank. In that case, a single cooling tank is sometimes not sufficient for storing the fuel during, for example, shop work. In addition to being used for shop work, the invention can also be used, for example, when refuelling at a filling station, or between two vehicles. This at least one additional cooling tank is smaller than the cooling tank 1.