Liquiefying a gaseous medium

Abstract

An arrangement comprising at least one liquefaction plant for liquefying a gaseous medium to produce a liquefied medium; and at least one storage tank for storing the liquefied medium. A first transfer line is provided which is connected between the liquefaction plant and the storage tank, for transferring liquefied medium from the liquefaction plant into the storage tank. A second transfer line is connected between the liquefaction plant and the storage tank, for transferring gaseous medium from the storage tank into the liquefaction plant. The second transfer line, which used for transferring medium from the storage tank into the liquefaction plant, is arranged so that it is routed at least partially through the area of the storage tank in which the liquefied medium is stored in use.

Claims

1. An arrangement comprising: at least one liquefaction plant (V) for liquefying a gaseous medium to produce a liquefied medium, at least one storage tank (S) for storing the liquefied medium, a first transfer line (3) connected between the liquefaction plant (V) and the storage tank (S) for transferring liquefied medium from the liquefaction plant (V) into the storage tank (S), a second transfer line (4, 4) connected between the liquefaction plant (V) and the storage tank (S) for transferring gaseous medium from the storage tank (S) into the liquefaction plant (V), wherein the second transfer line (4, 4) is routed at least partially through an area of the storage tank (S) in which the liquefied medium is stored in use, at least one first shut-off valve (a) provided in said first transfer lines (3) and at least one second shut-off valve provided in said second transfer line (4, 4), a bypass line (5) connecting the first and second transfer lines (3, 4, 4), and a bypass shut-off valve (c) provided in the by-pass line (5), wherein the bypass line (5) connects the first and second transfer lines (3, 4, 4) at a point between the liquefaction plant (V) and the shut-off valves (a, b) of the first and second transfer lines, and a control element, wherein the control element is configured such that, after a standstill phase of the liquefaction plant (V) and before the transfer of liquefied medium from the liquefaction plant (V) into the storage tank (S), the control element performs a transfer line cooling phase, in which the shut-off valves (a, b) of the transfer lines are closed and the bypass line shut-off valve (c) is opened, so that liquefied medium from the liquefaction plant (V) can flow through via partial sections of the first transfer line (3), the bypass line (5), the second transfer line (4, 4) transfer lines (3, 4, 4), and back into the liquefaction plant (V).

2. An arrangement according to claim 1, wherein an outlet of the first transfer line (3) into the storage tank (S) is provided adjacent to a first side wall of the tank (S) and an inlet of the second transfer line (4, 4) is provide adjacent to a second side wall, said second side wall being provided on the side of the tank (S) opposite to the first side wall.

3. The arrangement according to claim 1, wherein the bypass line (5) is arranged adjacent to the storage tank (S).

4. The arrangement according to claim 1, wherein the bypass line (5) is connected between a point on the first transfer line (3) upstream of the first shut-off valve (a) and a point on the second transfer line (4, 4, 4) downstream of the second shut-off valve (b).

5. The arrangement according to claim 4, wherein an outlet of the first transfer line (3) into the storage tank (S) is provided adjacent to a first side wall of the tank (S) and an inlet of the second transfer line (4, 4) is provide adjacent to a second side wall, provided on the side of the tank (S) opposite to the first side wall.

6. The arrangement according to claim 1, wherein the second transfer line (474) is routed through the area of the storage tank (S) from one end of the storage tank to another end of the storage tank.

7. The arrangement according to claim 1, wherein the storage tank (S) is a double-walled tank, having an outer tank (1) and an inner tank (2).

8. The arrangement according to claim 1, wherein at least some of the transfer lines are vacuum insulated.

9. A method for cooling the transfer lines (3, 4, 4) of an arrangement according to claim 1, after a standstill phase of the liquefaction plant (V), the method comprising: operating in a cooling mode wherein liquid medium is fed through the by-pass line that connects the first transfer line and the second transfer line, so as to by-pass the storage tank (S), and switching to a normal transfer mode wherein liquefied medium is transferred from the liquefaction plant (V) into the storage tank (S).

10. The method according to claim 9, wherein the cooling mode comprises: closing the shut-off valves (a, b) in the first and second transfer lines, and opening the bypass line shut-off valve (c), so that liquefied medium is led from the liquefaction plant (V), through the first transfer line (3), the bypass valve (5), and the second transfer line (4, 4), and back into the liquefaction plant (V).

11. The method according to claim 9, wherein the cooling mode is carried out until a predetermined temperature has been reached in at least one section of the first and second transfer lines (3, 4, 4, 4).

12. The method according to claim 9, wherein the medium to be liquefied is hydrogen, a noble gas, oxygen, nitrogen, or a hydrocarbon mixture.

13. The arrangement according to claim 1, wherein the storage tank (S) is a vacuum insulated storage tank.

14. The arrangement according to claim 8, wherein all of the transfer lines are vacuum insulated.

15. The method according to claim 9, wherein the medium to be liquefied is hydrogen, helium, neon, argon, oxygen, nitrogen, or natural gas.

16. A method for cooling the transfer lines (3, 4, 4) of an arrangement, said arrangement comprising at least one liquefaction plant (V) for liquefying a gaseous medium to produce a liquefied medium, at least one storage tank (S) for storing the liquefied medium, a first transfer line (3) connected between the liquefaction plant (V) and the storage tank (S) for transferring liquefied medium from the liquefaction plant (V) into the storage tank (S), a second transfer line (4, 4) connected between the liquefaction plant (V) and the storage tank (S) for transferring gaseous medium from the storage tank (S) into the liquefaction plant (V), wherein the second transfer line (4, 4) is routed at least partially through an area of the storage tank (S) in which the liquefied medium is stored in use, at least one first shut-off valve (a) provided in said first transfer lines (3) and at least one second shut-off valve provided in said second transfer line (4, 4), a bypass line (5) connecting the first and second transfer lines (3, 4, 4), and a bypass shut-off valve (c) provided in the by-pass line (5), wherein the bypass line (5) connects the first and second transfer lines (3, 4, 4) at a point between the liquefaction plant (V) and the shut-off valves (a, b) of the first and second transfer lines, the method comprising, after a standstill phase of the liquefaction plant (V): (a) operating in a cooling mode wherein liquid medium is fed through the by-pass line that connects the first transfer line and the second transfer line, so as to by-pass the storage tank (S), wherein the cooling mode comprises: closing the shut-off valves (a, b) in the first and second transfer lines, and opening the bypass line shut-off valve (c), so that liquefied medium is led from the liquefaction plant (V), through the first transfer line (3), the bypass valve (5), and the second transfer line (4, 4), and back into the liquefaction plant (V), and (b) switching to a normal transfer mode wherein liquefied medium is transferred from the liquefaction plant (V) into the storage tank (S).

17. A method for cooling the transfer lines (3, 4, 4) of an arrangement, said arrangement comprising at least one liquefaction plant (V) for liquefying a gaseous medium to produce a liquefied medium, at least one storage tank (S) for storing the liquefied medium, a first transfer line (3) connected between the liquefaction plant (V) and the storage tank (S) for transferring liquefied medium from the liquefaction plant (V) into the storage tank (S), a second transfer line (4, 4) connected between the liquefaction plant (V) and the storage tank (S) for transferring gaseous medium from the storage tank (S) into the liquefaction plant (V), wherein the second transfer line (4, 4) is routed at least partially through an area of the storage tank (S) in which the liquefied medium is stored in use, at least one first shut-off valve (a) provided in said first transfer lines (3) and at least one second shut-off valve provided in said second transfer line (4, 4), a bypass line (5) connecting the first and second transfer lines (3, 4, 4), and a bypass shut-off valve (c) provided in the by-pass line (5), wherein the bypass line (5) connects the first and second transfer lines (3, 4, 4) at a point between the liquefaction plant (V) and the shut-off valves (a, b) of the first and second transfer lines, the method comprising, after a standstill phase of the liquefaction plant (V): (a) operating in a cooling mode wherein liquid medium is fed through the by-pass line that connects the first transfer line and the second transfer line, so as to by-pass the storage tank (S), and (b) switching to a normal transfer mode wherein liquefied medium is transferred from the liquefaction plant (V) into the storage tank (S), wherein the cooling mode is carried out until a predetermined temperature has been reached in at least one section of the first and second transfer lines (3, 4, 4, 4).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Specific embodiments of the invention will now be described in detail by way of example only and with reference to the accompanying drawings in which:

(2) FIG. 1 shows a previously known arrangement;

(3) FIG. 2 shows an arrangement according to a first embodiment of the invention;

(4) FIG. 3 shows an arrangement according to a second embodiment of the invention;

(5) FIG. 4 shows an arrangement according to another embodiment of the invention; and

(6) FIG. 5 shows an arrangement according to a further embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

(7) The figures each show a liquefaction plant V represented simply as a black box, as well as a diagrammatically represented storage tank S. In general, said storage tank comprises an outer tank 1 as well as an inner tank 2, wherein the clearance between inner tank and outer tank is designed to be vacuum insulated.

(8) FIGS. 2 to 5 show various embodiments of invention which all provide an improved operation over the previously known arrangement described above. In FIGS. 2 to 5 similar components are given the same reference numerals as in FIG. 1.

(9) In FIG. 2, it will be noted that the second (return) transfer line 4, which is used for transferring the medium from the storage tank S into the liquefaction plant V, has a different configuration. In FIG. 2, an outlet of the first transfer line 3 into the storage tank S is provided adjacent to a first side wall, Sx, of the tank S and an inlet of the second transfer line is provide adjacent to a second side wall, Sy, the second side wall being the opposite side of the tank S to the first side wall. This means that the inlet of the second transfer line 4 (used for transferring gaseous medium from the storage tank S into the liquefaction plant V) is located as far as possible from the outlet of the first transfer line 3. Furthermore, the second transfer line 4 is routed so that when the liquid medium is present in the storage tank S, the length of the transfer line 4 which is routed in the section of the inner tank 2 containing the liquid medium is maximized. In other words, the second transfer line 4 is routed so that, in use, as much of the line 4 is surrounded by the liquid medium as possible.

(10) FIG. 3 shows an arrangement in which transfer lines 3 and 4 are arranged in the same way as shown in FIG. 2. In FIG. 3, a by-pass line 5 is provided between the first transfer line 3 and the second (return) transfer line 4, and a shut-off valve c is provided in the by-pass line 5. The bypass line 5 connects the first transfer line 3 at a point between the liquefaction plant V and the shut-off valve a, to the second transfer line 4 at a point between the liquefaction plant V and the shut-off valve b. In other words, the by-pass line 5 is connected to the first transfer line 3 upstream of shut-off valve a and connected to the second transfer line 4 downstream of shut-off valve b.

(11) A further embodiment is shown in FIG. 4, and again similar components are given the same reference numerals In FIG. 4, the second (return) transfer line 4 is arranged in such a manner that when the liquid medium is present in the storage tank S (inner tank 2), the line 4 is routed at least partially through the portion of the storage tank S or of the inner tank 2 in which the liquefied medium is stored. FIG. 4 is similar to the embodiment of FIG. 2 except that the second transfer line 4 is arranged in a different position with respect to the sidewall of the tank. The embodiment of FIG. 5 corresponds to the embodiment of FIG. 4, but with the inclusion of the bypass line 5 and shut-off valve c, as in FIG. 3.

(12) The arrangement of the transfer lines 3 and 4 within the storage tank, as represented in FIGS. 2 to 5, is an improvement of the arrangement of the transfer lines within the storage tank as represented in FIG. 1. If constructively possible, the arrangement as represented in FIG. 2, or FIG. 3 is always selected since this maximizes the operational benefits.

(13) During a start-up procedure, prior to normal operation, it is necessary to cool down the storage tank to the desired operational temperature, at or near liquid helium temperature. In order to do this, cold gaseous helium is passed from the liquefaction plant V through transfer line 3 into the storage tank S. The cold gaseous helium passes through the tank and cools the tank. The cold gaseous helium is then recirculated back to the plant V through the return line 4.

(14) Some embodiments described above include a by-pass line. It will be appreciated that the arrangement and use of the bypass line 5 is independent of the arrangement of the transfer lines within the storage tank.

(15) The by-pass line 5 can be provided at any point which connects the first transfer line 3 upstream of shut-off valve a and the second transfer line 4 downstream of shut-off valve b. However, in a preferred embodiment the by-pass line 5 is provided in the immediate vicinity of, or substantially adjacent to, the storage tank. In practical terms, this means that it is arranged as close as constructively possible to the storage tank. This means that the lengths of those sections of the transfer lines that do not come in direct contact, during the cooling phase, with the medium circulating via the transfer lines and the bypass line are reduced or minimized. In other words, a maximum length of the transfer lines is cooled during the cooling phase, and only the relatively short lengths between the valves and the storage tank are not cooled.

(16) The embodiments of the invention including by-pass lines have additional steps of operations, which are described below.

(17) After a standstill phase or the renewed startup of the liquefaction plant V, before the transfer of liquefied medium into the storage tank S, a cooling of the transfer lines is carried out. In the transfer lines cooling phase, liquefied medium is led from the liquefaction plant V via the transfer lines 3 and 4/4 as well as the bypass line 5. During this cooling phase, the shut-off valves a and b are closed and only the shut-off valve c of the bypass line 5 is opened. Since the medium used for cooling the transfer lines 3 and 4/4 is now not led through the storage tank S, the heat is effectively prevented from being introduced from the transfer line 3 into the storage tank S. The liquefied medium is fed through the by-pass line 5 until a predetermined, desired temperature is reached.

(18) After the cooling of the transfer lines 3 and 4/4 to the desired temperature has occurred, the shut-off valve c is closed and the shut-off valves a and b are opened. This means that the medium liquefied in the liquefaction plant V is now transferred via the transfer line 3 directly into the storage tank S. At the same time, medium can be transferred from the storage tank S via the transfer line 4/4 back into the liquefaction plant V.

(19) While the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

(20) The entire disclosures of all applications, patents and publications, cited herein and of corresponding United Kingdom patent application No. GB 1711979.3, filed Jul. 25, 2017 are incorporated by reference herein.

(21) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(22) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(23) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.