US3154394A - Switching system comprising a source of liquified gas - Google Patents

Description

Oct. 27, 1964 SWITCHING SYSTEM COMPRISING A SOURCE OF LIQUIFIED GAS Filed April 27, 1961 o GAS F E iRlGERAToR t 1 1 10 11 3 2 l r\ K HEAT zxfi em' EXCHANGER PRIOR ART P O.

6 T 7 COLD As 1 REFRIGERATOR I 1* 8 f 2 17 1 a 4 D D u 4 s V 21 525 3 22 244 a '9 4 27 2s a z 929 27 INVENTOR United States Patent 3,154,394 SWITCHING SYSTEM COMPRISING A SOURCE OF LEQUIFIED GAS Johannes van der Ster, Emmasingel, Eindhoven, Netherlands, assignor to North American Philips Company,

lnc., New York, N.Y., a corporation of Delaware Filed Apr. 27, 1961, Ser. No. 106,022 Claims priority, application Netherlands May 6, 1960 3 Claims. (CI. 62-40) The invention relates to a system comprising a plurality of vapor bubble or lift pumps for lifting a liquid, for example, liquid gas. This liquid gas may be, for example, liquid air, nitrogen, methane, or the like.

A vapor bubble or lift pump is to be understood to mean a liquid uptake implement consisting of a short, wide duct or a vessel termed the downtake duct which communicates with the lower end of a narrower uptake duct, to which, at a place below the liquid level in the downtake duct heat can be supplied so that vapor bubbles are produced in the uptake duct, which bubbles convey the liquid in the uptake duct in an upward direction in the manner of a gas introduced into the uptake duct of a so-called mammoth pump.

The invention provides a system in which such vapor bubble pumps are utilized in an advantageous and eificient manner.

In the system according to the invention vapor bubble or lift pumps with their heat supply devices, also termed heating devices, and with their accessories are used as switching elements. In this case they may serve, for example, to replace valves, of which the use, under certain conditions, for example, with very low temperatures and with liquid gas traversing the valves, may give rise to difiiculties in which the valves are likely to be jammed.

The advantages of the system according to the invention are clearly manifest in a system comprising a plurality of heat exchangers which are adapted to be switched over. This applies, for example, to a cold gas refrigerator, which comprises, as is known, one or more walls (or heads) cooled during operation to an extent such that gas is condensed thereon. Gas, for example, air is conveyed towards this cold wall, preferably on its path to Wards the wall through a heat exchanger, constituents such as carbon dioxide and water which form impurities of the condensate are separated out of the gas.

Such heat exchangers are known from U.S. Patent No. 2,900,798 and from U.S. Patent No. 2,899,381. In these patents the impurities are separated out in the form of snow on cooled plates, along which is conveyed the gas to be purified.

An important further construction of such a heat exchanger is described in U.S. Patent No. 2,999,364. In this case the impurities are separated out in the form of snow on a partition which is pervious to the gas, for example, a gauze partition, which is efficiently cooled. Such heat exchangers become clogged with snow after a given period of operation. The heat exchanger then has to be switched off in order to remove the snow. In order to permit a continuous operation of the system, a second heat exchanger, on which no snow has been formed is then switched on.

In one embodiment of the invention each heat exchanger in such a system is connected, in order to change over the heat exchangers, to a vapor bubble pump and the heating devices for these pumps, are housed in a switching system.

If the system comprises a cold gas refrigerator, the outlet duct for liquid gas of this cold gas refrigerator in a further embodiment of the invention may be connected with the vapor bubble pumps while the heat exchangers are connected with the space around the cold 3,154,394 Patented Oct. 27, 1964 head of the cold gas refrigerator and are adapted to separate out impurities from the gas conveyed towards the cold head.

The heat exchangers may constitute units which communicate through a space for the supply of gas vapor, with the space around the cold head. These units are arranged outside the cold head. The connecting ducts between the heat exchangers and the space around the cold head may then be formed by uptake ducts which are bent over in a downward direction from a place located above the head to the space around the head. This embodiment has an advantage which will be explained with reference to the drawing.

The lower ends of the uptake pipes of the vapor lift or bubble pumps in a practical embodiment are arranged in a vessel to be filled with liquid gas so that this liquid blocks these lower ends. This vessel then constitutes the downtake pipes of the vapor bubble pumps. If a separate downtake pipe is provided with a pump, this pipe may be arranged to surround the uptake duct, so that the lower end of the latter is also blocked by liquid in the downtake duct.

The invention will be described more fully with reference to the diagrammatical drawing in which:

FIG. 1 shows a diagram of a known system comprising cocks or stop valves,

FIG. 2 shows a diagram of one embodiment of a system according to the invention, and

FIG. 3 is a fragmentary diagrammatic view of an alternate embodiment of outlet ducts.

Referring more particularly to the two diagrammatic drawings the reference numeral 1 designates a cold head and the space surrounding it in a cold gas refrigerator. In both diagrammatic drawings provision is made of two heat exchangers 2 and 3, for example, of the kind described in the aforesaid patents.

Gas to be purified can be supplied to each heat exchanger 2 and 3 respectively at points 4 and 5. Subsequent to purification the gas can be conveyed in these systems through the ducts 6 and 7 from the spaces in the heat exchangers 2 or 3 towards the cold head 1.

The gas to be purified may be also supplied to a heat exchanger 28 or 29 at 4 or 5 and so conducted away subsequent to purification in the heat exchanger 28 or 29, through an outlet duct 8 or 9 as shown in FIG. 3. The ducts 6 and 7 then serve to conduct away gas or vapor supplied through a dilferent duct, for example, the ducts 10 and 11 in FIG. 1, to the heat exchangers 2 or 3 to cool the gas supplied to these heat exchangers through the ducts 4 or 5 As is shown in FIG. 7, liquid gas condensed on the cold head 1 is conducted away through the ducts 12 and by means of a three-way cock or valve 13 either to the duct 10 and the heat exchanger 2, or to the duct 11 and the heat exchanger 3.

The ducts 6 and 7 join at a three-way cock or valve 14, which is capable of supplying gas or vapor via the duct 15 to the chamber surrounding the cold head 1.

As is shown in FIG. 1, the cocks 13 and 14 are set first, for example, so that the heat exchanger 2 is operative. When this heat exchanger 2 is filled with impurities from the gas supplied at 4 to a given extent, the cooks 13 and 14 are switched over, so that the heat exchanger 3 becomes operative and the heat exchanger 2 can be purged of the collected impurities.

This known construction has the disadvantage that the cocks are likely to be jammed. Moreover, the transition from the operation with one heat exchanger to the operation with the other heat exchanger is abrupt. These disadvantages are completely avoided in the system according to the invention, of which an embodiment is shown in FIG. 2.

In this case, liquid gas obtained on the cold head 1 is conveyed through the duct 12 to a vessel 16. In this vessel the lower ends of uptake ducts 17 and 18 of vapor bubble pumps are arranged. The uptake duct 17 communicates with the heat exchanger 2 and the uptake duct 18 communicates with the heat exchanger 3.

The heating devices of the vapor bubble pumps are designated by 19 and 20. They are formed in this case by electrically heated elements, of which the current supply wires and the current outlet wires 21 and 22 and 23 and 24 respectively are connected to terminals 25 and 26 respectively of a switch 27.

The rising ducts 6 and 7, which conduct away gas or vapor from the heat exchangers, are bent over from a place P or Q respectively above the head 1 downwards towards the head so that at P and Q heat barriers are formed. The cock 14 of FIG. 1 may then be completely dispensed with.

The cock 13 is replaced in FIG. 2 by the vapor bubble pumps, which can be changed over by means of the switch 27. The switching device 27 may be constructed so that it is adapted to co-operate first with the heat exchanger 2, so that liquid gas is conducted through the uptake duct 17, then with the two heat exchangers, so that the two vapor bubble pumps are operative, and finally with the heat exchanger 3 and the vapor bubble pump 18.

The vessel 16 is to be proportioned so that a satisfactory change over is possible. The liquid in the vessel 16 constitutes at the same time a satisfactory insulation for the lower ends of the rising ducts 17 and 18 of the vapor bubble pumps.

The system may comprise more than two heat exchangers, each of which is adapted to co-operate with vapor bubble pumps.

While I have shown and described the preferred embodiment of my invention, it will be understood that the latter may be embodied otherwise than as herein specifically illustrated or described and that in the illustrated embodiment certain changes in the details of construction and in the arrangement of parts may be made without departing from the underlying idea or principle of the invention within the scope of the appended claims.

What is claimed is:

1. A system for switching over heat exchangers associated with a cold source comprising a plurality of heat exchangers adapted to be switched over, means for feeding gas to said heat exchangers and said cold source and condensing the output therefrom to form liquified gas, a vessel having its bottom located at a level below the bottoms of said heat exchangers, a conduit connecting said cold source to said vessel whereby said liquified gas is conducted thereto and stored therein, a plurality of vapor lift pumps having the lower ends thereof submerged in the liquified gas in said vessel and upper ends in communication with said heat exchangers which are adapted to transport said liquified gas in an upward direction to said heat exchangers; heating devices for each vapor lift pump, a source of power, and current supply wires provided with a switch for electrically connecting said source of power to selected current supply wires whereby said vapor lift pumps are electrically actuated and function as switching elements for said heat exchangers.

2. A system for switching over heat exchangers associated with a cold source as claimed in claim 1, wherein said means for feeding gas to said cold source from said heat exchangers are U-shaped rising ducts which are so constructed as to prevent cold from the cold source returning therethrough to said heat exchangers.

3. A system for switching over heat exchangers associated with a cold source as claimed in claim 1, wherein the latter is a cold gas refrigerator.

References Cited in the file of this patent UNITED STATES PATENTS 572,449 Rich Dec. 1, 1896 2,002,941 Frankl May 28, 1935 2,008,334 Frankl June 22, 1937 2,637,531 Davidson May 5, 1953 2,651,508 Bready Sept. 8, 1953 2,677,252 Rice et a1. May 4, 1954 2,749,714 Hunter June 12, 1956 2,853,953 Hallman Sept. 30, 1958 2,958,203 Trepp Nov. 1, 1960 2,959,926 Haringhuizen Nov. 15, 1960 2,963,874 Means Dec. 13, 1960 2,964,916 Keeping Dec. 20, 1960 FOREIGN PATENTS 776,186 Great Britain June 5, 1957

Claims (1)

1. A SYSTEM FOR SWITCHING OVER HEAT EXCHANGERS ASSOCIATED WITH A COLD SOURCE COMPRISING A PLURALITY OF HEAT EXCHANGERS ADAPTED TO BE SWITCHED OVER, MEANS FOR FEEDING GAS TO SAID HEAT EXCHANGERS AND SAID COLD SOURCE AND CONDENSING THE OUTPUT THEREFROM TO FORM LIQUIFIED GAS, A VESSEL HAVING ITS BOTTOM LOCATED AT A LEVEL BELOW THE BOTTOMS OF SAID HEAT EXCHANGERS, A CONDUIT CONNECTING SAID COLD SOURCE TO SAID VESSEL WHEREBY SAID LIQUIFIED GAS IS CONDUCTED THERETO AND STORED THEREIN, A PLURALITY OF VAPOR LIFT PUMPS HAVING THE LOWER ENDS THEREOF SUBMERGED IN THE LIQUIFIED GAS IN SAID VESSEL AND UPPER ENDS IN COMMUNICATION WITH SAID HEAT EXCHANGERS WHICH ARE ADAPTED TO TRANSPORT SAID LIQUIFIED GAS IN AN UPWARD DIRECTION TO SAID HEAT EXCHANGERS; HEATING DEVICES FOR EACH VAPOR LIFT PUMP, A SOURCE OF POWER, AND CURRENT SUPPLY WIRES PROVIDED WITH A SWITCH FOR ELECTRICALLY CONNECTING SAID SOURCE OF POWER TO SELECTED CURRENT SUPPLY WIRES WHEREBY SAID VAPOR LIFT PUMPS ARE ELECTRICALLY ACTUATED AND FUNCTION AS SWITCHING ELEMENTS FOR SAID HEAT EXCHANGERS.

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