Cooling of a vaporized content of a liquefied gas for the purpose of powering machinery, plants or vehicles

Abstract

A fuel system for a liquefied gas drive system. The fuel system has a liquefied gas tank and a cooling system for the vaporized content of liquefied gas, which comprises a liquid nitrogen tank, a nitrogen pump, a heat exchanger, and a nitrogen cooler, which are connected to each other in a pipework circuit. The heat exchanger is arranged in the interior of the liquefied gas tank. Also disclosed are a vehicle, a plant and a machine, in each case with a fuel system, and a method for cooling the vaporized content of liquefied gas of a liquefied gas drive system.

Claims

1. A fuel system for a liquefied gas drive system, comprising: a liquefied gas tank; and a cooling system, wherein the cooling system comprises a liquid nitrogen tank, a nitrogen pump, a heat exchanger, and a nitrogen cooler, which are connected to each other in a pipework circuit, and wherein the heat exchanger is arranged in an interior of the liquefied gas tank, further comprising at least one extraction system with a flue, to which the liquefied gas tank is connected via at least one pipe configured to discharge gas from the liquefied gas tank through the flue, wherein at least one of: the cooling system further has at least one of an outlet that is likewise connected to the flue and that can be closed or opened for discharging nitrogen heated in the heat exchanger through the flue, or a pressure relief outlet connected to the flue to limit a maximum pressure in the pipework circuit by discharge through the flue, or the fuel system further comprises a nitrogen purge system connected to the flue to feed nitrogen into the flue.

2. The fuel system in accordance with claim 1, wherein the heat exchanger has a multiplicity of cooling tubes through which nitrogen can be fed.

3. The fuel system in accordance with claim 2, wherein the multiplicity of cooling tubes comprises at least two cooling tubes, at least sections of which extend along a respective ring about a common central axis.

4. The fuel system in accordance with claim 1, wherein the at least one extraction system comprises at least one burner to flare discharged gas.

5. The fuel system in accordance with claim 1, further comprising a pressurization system for the liquefied gas tank, which comprises a vaporization heat exchanger to vaporize liquefied gas from the liquefied gas tank, together with a pipe to introduce vaporized liquefied gas into the liquefied gas tank.

6. The fuel system in accordance with claim 1, wherein the cooling system comprises a compressed nitrogen gas reservoir which is connected via a pipe to the liquid nitrogen tank.

7. A vehicle with a liquefied gas drive system, comprising a fuel system in accordance with claim 1, to provide liquefied gas for the drive system.

8. A plant or machine with a liquefied gas drive system, wherein for provision of liquefied gas for a drive system, the plant or machine has a fuel system in accordance with claim 1.

9. A method for cooling vaporized content of a liquefied gas of a liquefied gas drive system, wherein the liquefied gas is arranged in a liquefied gas tank of a fuel system in accordance with claim 1, and wherein the method comprises feeding nitrogen through the heat exchanger located in the liquefied gas tank.

10. The method in accordance with claim 9, wherein the cooling system has at least one of an outlet that can be closed or opened for nitrogen heated in the heat exchanger, or a pressure relief outlet to limit a maximum pressure in the pipework circuit, and the method comprises: in a first phase, feeding nitrogen through the pipework circuit of the cooling system with the outlet and pressure relief outlet closed, and in a second phase, releasing nitrogen through the outlet for nitrogen heated in the heat exchanger, or the pressure relief outlet.

11. The method in accordance with claim 9, wherein the method comprises: during a first period of time, cooling vaporized gas by means of the cooling system, and during a second period of time, venting vaporized gas through the extraction system.

12. A fuel system for a liquefied gas drive system, comprising: a liquefied gas tank; and a cooling system, wherein the cooling system comprises a liquid nitrogen tank, a nitrogen pump, a heat exchanger, and a nitrogen cooler, which are connected to each other in a pipework circuit, and wherein the heat exchanger is arranged in an interior of the liquefied gas tank, further comprising at least one extraction system with a flue, to which the liquefied gas tank is connected via at least one pipe configured to discharge gas from the liquefied gas tank through the flue, wherein the cooling system further has a pressure relief outlet connected to the flue, to limit a maximum pressure in the pipework circuit by discharge through the flue.

13. A fuel system for a liquefied gas drive system, comprising: a liquefied gas tank; and a cooling system, wherein the cooling system comprises a liquid nitrogen tank, a nitrogen pump, a heat exchanger, and a nitrogen cooler, which are connected to each other in a pipework circuit, and wherein the heat exchanger is arranged in an interior of the liquefied gas tank, further comprising at least one extraction system with a flue, to which the liquefied gas tank is connected via at least one pipe configured to discharge gas from the liquefied gas tank through the flue, the fuel system further comprising a nitrogen purge system connected to the flue to feed nitrogen into the flue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In what follows, preferred embodiments of the invention will be described in more detail with the aid of figures. It is to be understood that individual elements and components shown are not necessarily included, and/or can be combined in a manner that differs from that illustrated.

(2) Reference symbols for corresponding elements are used across the figures and are not necessarily described anew for each figure.

(3) Here, in schematic form:

(4) FIG. 1 shows an exemplary embodiment of a fuel system in accordance with the invention;

(5) FIG. 2a shows a view of a heat exchanger of one embodiment of an inventive fuel system;

(6) FIG. 2b shows a view from another perspective of the heat exchanger shown in FIG. 2a; and

(7) FIG. 3 shows a detail of a cross-sectional view of a heat exchanger of a variant when functioning.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) FIG. 1 schematically illustrates an exemplary embodiment of an inventive fuel system 1 in an orientation intended for operational conditions. The fuel system 1, which is, or can be, installed in a vehicle (e.g., a water or land vehicle), or in a plant or machine (in each case) with a liquefied gas drive system, comprises a cooling system 10 and a tank chamber 20 with a liquefied gas tank 21. The latter is configured so as to be connected via a pipe 22 to a drive system (not shown), or is already connected to the latter.

(9) The cooling system 10 has a liquid nitrogen tank 11, a nitrogen pump 12, a heat exchanger 13, and a nitrogen cooler 14, which are interconnected in a pipework circuit. Via a pipe with a (preferably controllable) valve, the liquid nitrogen tank 11 is connected to a compressed nitrogen gas reservoir 16, which in the present case is designed as a compressed nitrogen gas cylinder. With the aid of the compressed nitrogen gas reservoir 16, an operating pressure can be set in the liquid nitrogen tank 11, which determines the cooling capacity of the heat exchanger 13.

(10) The heat exchanger 13 is arranged in the interior of the liquefied gas tank 21, in particular in an upper region, above a liquid level (not shown) of the liquefied gas contained in the tank, so that a vaporized gas content can flow around the heat exchanger 13 and can condense on it.

(11) The nitrogen pump 12 is configured so as to circulate nitrogen through the pipework circuit. It is connected via a pipe 15 comprising a valve with the liquid nitrogen tank 11 and in the present case can be bypassed (in particular in the event of a defect of the nitrogen pump) by a pipe 17 with a valve.

(12) The nitrogen cooler 14 can, for example, be electrically operated, for example by means of a power generator (not shown), which in turn can be operated with liquefied gas from the liquefied gas tank 21.

(13) The fuel system 1 as illustrated, furthermore, has a pressurization system, which in the present case is arranged in the tank chamber 20 for the liquefied gas tank; this comprises a vaporization heat exchanger 23 for purposes of vaporizing liquefied gas from the liquefied gas tank, together with a pipe 24 (with a valve) for purposes of introducing vaporized liquefied gas into the liquefied gas tank.

(14) The liquefied gas tank 21 is connected to an extraction system 30 via a pipe 25 with a pressure relief valve 26. If a prescribed maximum pressure in the liquefied gas tank 21 is exceeded, vaporized gas can be released in this manner into the environment, as indicated in the figure by an arrow.

(15) The extraction system includes a flue 31, in the upper eighth of which is arranged a burner 32 for the systematic flaring of vaporized gas. A deflagration flame arrester 33 is arranged in the flue 31 between the liquefied gas tank 21 and the burner 32; this is intended to prevent any flashback of flames into the liquefied gas tank 21.

(16) In addition, the fuel system 1 in the embodiment shown comprises a nitrogen purge system 40 with a nitrogen reservoir 41, which in the present case comprises a compressed gas cylinder and via a pipe 42 (which comprises at least one valve) is connected to the extraction system 30. Nitrogen can thus be fed through the pipe 42 to the extraction system, in particular to the flue 31, and at the same time, if necessary, vaporized gas that has been introduced can be diluted to a non-flammable concentration. The nitrogen purge system thus provides additional safety for the fuel system.

(17) In the present embodiment, the fuel system, to increase safety by means of redundancy, comprises both the nitrogen purge system 40 and the burner 32; in alternative embodiments, neither, or just one, of these two units is included.

(18) The cooling system 10 comprises an outlet 18 for nitrogen heated in the heat exchanger 13 and a pressure relief outlet 19 for purposes of limiting a maximum pressure in the pipework circuit (in particular in the liquid nitrogen tank); in the present case these are both designed as pressure relief valves and lead into the flue 31 of the extraction system 30. Via the outlet 18, the fuel system 1 can be operated as an open system, bypassing the nitrogen cooler 14, for example in the event of a defect of the nitrogen cooler 14 or the pump 12, for a period of time until a repair can be made.

(19) FIGS. 2a and 2b show, in two different perspectives, an exemplary heat exchanger 13 which is used in an advantageous variant of an embodiment of an inventive fuel system 1: In an orientation of the liquefied gas tank intended for operational, FIG. 2a shows the heat exchanger from above, the viewing direction onto the figure thus runs vertically, whereas FIG. 2b shows the heat exchanger 13 from the side, that is to say, with a horizontal viewing direction onto the figure.

(20) The heat exchanger 13 has a multiplicity of cooling tubes 131, 131, 131, 131a, 131b, . . . , 131n, through which nitrogen can pass; these run along a respective ring about a common central axis A, which in FIG. 2a runs in the viewing direction and therefore can only be seen as a point. It is to be understood that the number of cooling tubes illustrated in each case is purely exemplary.

(21) The respective rings of the cooling tubes visible in FIG. 2a have different radii, the cooling tube 131 therefore runs as a ring around the cooling tube 131 and the latter in turn runs as a ring around the cooling tube 131. Here the three cooling tubes 131, 131 and 131 are arranged in a common layer, that is to say, they are not offset relative to one another along the central axis A. Gaps S are formed (also running coaxially) between the cooling tubes 131, 131 and 131, through which the vaporized gas can flow.

(22) The cooling tubes 131, 131a, 131b, 131n, and the cooling tubes not provided with reference symbols, shown in FIG. 2b, on the other hand, are stacked one above another in the direction of the central axis, and thus form a plurality of layers. Here the respective rings in the present case all have the same radius.

(23) The cooling tubes 131, 131, 131, 131a, 131b, . . . , 131n have a common feed pipe 132 and a common discharge pipe 133, through which nitrogen can be introduced and removed respectively. With regard to the flow of nitrogen therefore, the cooling tubes are connected in parallel. In FIG. 2b the intended flow direction for the nitrogen is indicated by arrows.

(24) A drip tray 134 is arranged on the lowest cooling tube in the present case 131n; this follows the circular path of the cooling tube 131n and extends vertically. Condensed vaporized gas can drain onto the drip tray 134.

(25) Such a draining process is illustrated in FIG. 3, which shows a section of the heat exchanger 13 in a cross-sectional view when functioning: As indicated by arrows, the vaporized gas, as it continues to cool, flows from top to bottom through the gaps S between the stacked cooling tubes until it is condensed in the region of the lowest cooling tube layer (with cooling tube 131n and other cooling tubes lying further inwards with respect to the central axis). The lowermost cooling tubes have in each case a vertically extending drip tray 134, 134, 134 in the form of a ring, onto which the liquid droplets F fall from the condensed vaporized gas.

(26) Disclosed is a fuel system 1 for a liquefied gas drive system. The fuel system has a liquefied gas tank 21 and a cooling system 10 for the vaporized content of the liquefied gas, which comprises a liquid nitrogen tank 11, a nitrogen pump 12, a heat exchanger 13, and a nitrogen cooler 14, which are connected to each other in a pipework circuit. The heat exchanger 13 is arranged in the interior of the liquefied gas tank 21.

(27) Also disclosed are a vehicle, a plant and a machine, in each case with a fuel system 1, and a method for cooling the vaporized content of the liquefied gas of a liquefied gas drive system.

(28) While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms comprise or comprising do not exclude other elements or steps, the terms a or one do not exclude a plural number, and the term or means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.

REFERENCE SYMBOLS

(29) 1 Fuel system 10 Cooling system 11 Liquid nitrogen tank 12 Nitrogen pump 13 Heat exchanger 14 Nitrogen cooler 15 Pipe 16 Compressed nitrogen gas reservoir 17 Pipe 18 Outlet for nitrogen heated in the heat exchanger 13 19 Pressure relief outlet 20 Tank chamber 21 Liquefied gas tank 22 Pipe to a drive system (not shown) 23 Vaporization heat exchanger 24 Pipe 25 Pipe 26 Pressure relief valve 30 Extraction system 31 Flue 32 Burner 33 Deflagration flame arrester 40 Nitrogen purge system 41 Nitrogen reservoir 42 Pipe 131, 131, 131, 131a, 131b, . . . , 131n Cooling tube 132 Feed pipe 133 Discharge pipe 134, 134, 134 Drip tray A Central axis F Fluid droplets S Gap