US1530461A

US1530461A - Recovery of helium

Info

Publication number: US1530461A
Application number: US590554A
Authority: US
Inventors: Arthur H Graham
Original assignee: Gas Equipment Engineering Corp
Current assignee: Gas Equipment Engineering Corp
Priority date: 1922-09-25
Filing date: 1922-09-25
Publication date: 1925-03-17
Anticipated expiration: 1942-03-17

Description

March 17, 1925. 1,530,461

A. H. GRAHAM RECOVERY OF HELIUM' Filed Sept. 25, 1922 2 Sheets-Sheet l v March 17, 1925. 1,530,461

A. H. GRAHAM- RECOVERY OF HELIUM Filed Sept. 25, 1922. 2 Sheets-Sheet 2 XQN mill km N K3 x Y i atented Mar. 17, 1925. UNITED STATES PATENT OFFICE.

ARTHUR H. GRAHAM, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO GAS EQUIP- MENT ENGINEERING CORPORATION, OF PHILADELPHIA, PENNSYLVANIA, A GOR- IPORATION OF DELAWARE.

RECOVERY OF HELIUM.

Application filed September 25, 1922. Serial No. 590,554.

To all whom it may conccwt: The refrigerating apparatus generally in- 65 Be it known that I, ARTHUR H. GRAHAM, dicated at 4, is a means for producing the a citizen of the United States, residing at region of refrigeration at 1 by the use of Philadelphia, in the county of Philadelphia air or nitrogen liquefied at' high pressure 5 and State of Pennsylvania, have invented 'which reaches the expansion valve 5 by way a new and useful Improvement in the Reof the path 6, and then traverses the coil covery of Helium, of which the following 7 and leaves by the path 8. This region is a specification. of refrigeration includes a heat exchanger,

The principal object of the present ingenerally lndlcated at 10. The heat exin vention is to facilitate the recovery of hechanger shown may be described as follium from natural gas and to simplify and lows: 11 is a shell subdivided by tube sheets, improve the process of recovery. Other obarranged in pairs with space 13 between jects of the invention will appear from the the plates of each pair, into high and low following description of the invention, and pressure chambers arranged in alternathe invention will be claimed at the end tion. The chambers a, a 0, and are nection with the accompanying drawings Z), 6 b and b are low pressure chamforming part hereof and in whichbars. The gas passes by tubes 14 connected Figure 1 is a view illustrating diagramwith the spaces 13 between the tube sheets 2n matically and schematically one form of apand extending across the chambers, and the paratus for the practice of the invention, gas finally reaches the separator. l by the and connection 15. There are tubes 16 which Fig. 2 is a similar view illustrating a connect the low pressure chambers and there modification. are what may be called jump pipes 17 which -13 The practice of the method of the invenconnect the lower portions of each of the tion may be briefly said to include three high pressure chambers with the next high principal steps or operations: First, total pressure chamber in the series. These jump liquefaction of substantially all of the conplpes 17 are also in communication with the stituents of the gas other than helium; secspaces 13 between the pairs of tube sheets 0nd, removal of the uncondensed helium at by way of the connections 18. The inlets a low temperature; and third, vaporization of expanders 19 are connected with the of the liquid in stages or fractionally at high pressure chambers as by 20, and the approximately the pressure under which it outlets of the expanders are connected as was condensed, thereby similarly effecting by 21 with the low pressure chambers. 22 condensation of nearly alike quantity of may be said to be an extension of the heat incoming gas so that a material economy exchanger 10, and is itself a heat exchanger is effected and the recovery of helium or cooler and the parts of it which corincreased. respond with the heat exchanger 10 are The invention will be further described marked with the same numerals, having in connection with the accompanying drawadded thereto the exponent a. 23 isacoui ings having particular reference to Fig. 1 pressor which is driven by power from a in which there is illustrated apparatus of suitable source of power applied as at 24:, which the heat exchanger shown at the botand also by such power as is available from tom of the sheet is in sectional elevation and the expanders 19 with which it is geared in which the apparatus shown at the upper as by gearing 25. part of the sheet is principally in sectional Natural gas entering at 26 is subjected plan, the view being thus distorted for the to the action of the compressor 23 and then sake of clearness in explanation. The seppasses as by 27 through cooler 28, through arator 1 is a part of a region of refrigerapipe 29, through cooler or heat exchanger tion at which helium will not liquefy and 22, and through tubes of heat exchanger 10 from which it is withdrawn at low temto separator 1, from which the liquid minus 5 perature by way of the outlet 2. In this substantially all of the helium passes by region substantially all of the other conpipe 30 back through the heat exchanger stituents of the natural gas will liquefy. 10 in a manner that will be presently dehereof, but will be first described in conhigh pressure chambers and the chambers 70 scribed, the products of vaporization or gas escaping at 31.

From the foregoing it will be evident to those skilled in the art that a stream of natural gas under pressure in traversing the tubes of the cooler 22 exchanges its heat, or some of it, with the medium surrounding those tubes, and such vapor as may condense is withdrawn by way of the connections 18, and generally speaking, the same action takes place in the tubes of the heat exchanger 10, so that finally the gas at a very low temperature and under pressure is subjected to the described action of the separator 1, and the helium, or substantially all of the helium, is led off at 2 at a low temperature. The liquid returning by enters the high pressure chamber a and is distributed in intimate contact with the tubes 14 therein, and a part of it evaporates, and the whole mass together with liquid condensed out of the natural gas between the pairs of tube sheets and escaping therefrom by the connection 18 is passed by the jump pipe 17 to the high pressure chamber a In the high pressure chamber a a portion of the liquid is vaporized and the resulting gas is passed through an expander 19 and back to the low pressure chamber 6 where there is an exchange of sensible heat from the incoming gas, and then passes by 16 to the low pressure chamber 6 and the remaining portion of the liquid passes by jump pipe 17 to high pressure chamber a and the described operation is repeated through the high and low pressure chambers and apparatus shown in the drawing progressively from the right towards the left. The number of repetitions is not ma terial and may be increased or diminished and a description of one such operation is believed to be suflicient.

The chambers in the apparatus 22 at the left in the drawing are cooled by returning low pressure gas and by the liquid which has condensed from the incoming natural gas and which is withdrawn from spaces 13 by the connection 32.

From the foregoing description it appears that, generally stated, there is established a region of refrigeration at which helium will not liquefy and from which it iswithdrawn at low temperature and at which substantially all the other constituents of the natural gas will liquefy. I do not desire to define the exact extent of that region because it may vary in different cases, but what I mean in a general way is the region included by the apparatus 10. Through that region of refrigeration I lead a supply of natural gas under pressure and I effect heat exchange between that incoming supply of gas and the outgoing gas and its liquid constituents, and this I do by vaporizing the liquid constituents of the outgoing gas along sulting from the vaporization is withdrawn,

expanded and cooled and the sensible heat of the expanded gases is used at low pressure, and this operation is repeated.

I believe that the described vaporization of the liquid in such a way that it will absorb the larger part of the heat of condensation of the incoming gas is new, and I also believe that it is new to provide the connections indicated at 18 and the jump pipes indicated at 17, so that it is an important feature of the invention that liquid from the incoming gas is taken from high pressure chambers and put as liquid into other high pressure chambers, by-passing the low pressure chambers, in contra-distinction to the customary practice in which such liquid was passed from a high pressure chamber directly into a low pressure chamber.

It may be said that the final refrigeration or liquefaction of the condensable gases in the vessel 1, is effected by expanding liquid nitrogen or air, and that the liquefaction of the other fractions of the incoming gas is accomplished according to equilibrium by fractional vaporization of the outgoing liquid in suitable contact with the incoming supply and at pressures and temperatures substantially the same at like points of condensation and vaporization, and it may also be said that by withdrawing the condensate from the incoming supply and adding it in stages to the outgoing gas supercooling of the condensate is avoided.

As shown in Figure 1, this is accomplished by providing high pressure chambers a.

a a and a", in the return circulation, but in Fig. 2 these chambers are omitted as are also the expanders 19. However in certain essentials the operation is the same. In Fig. 2thc parts which correspond to the parts shown in Fig. l. are marked with the same numerals with the addition of the exponent x. and in Fig. 2. 10" is a region of refrigeration consisting of a countercurrent interchanger wherein 11 is a tube or series of tubes arranged sons to be surrounded by a larger tube 14 with space 13* between the tubes which space 13* communicates with the chambers 35 located at one end of tubes 14". Pipes 18 connect chambers 35 with tubes 11". 21 is a chamber enclosing the greater portion of tubes 14*.

Gas which has been previously treated for the removal of water vapors and carbon dioxide enters at 26 where it is compressed by compressor 23* and enters water cooler. 28* by pipe 27*. Pipe 29* con ducts cooled gas to tubes 14* where it travels through the spaces 13* to pipe 15* which leads to the separator 1*. Here the gas comes in contact with a coil 7* which is cooled by liquid air or liquid nitrogen supplied by refrigeration plant 49. Practical- 1y all of the gas except the helium, is liquetied at this point and the helium, is removed through pipe 2*. The liquefied gas is returned to 10* through pipe 16* where there is an exchange of sensible heat from the incoming gas and continues through tubes 11* until a region is reached wherein the temperature causes evaporation according to the vapor pressures of the gas. At these points fractional condensation will take place within the spaces 13*, thereby utilizing the latent heat of evaporation of the gas in tubes 11* in condensing approximate ly a like amount of gasin spaces 13* until equilibrium between the amount of vapor and gas present in spaces 13* and in tubes 11* has been reached. The liquids so condensed in spaces 13* will collect in chambers 35 and will be removed by pipes 18* to tubes 11* where these liquids will exchange their sensible heat and heat of va porization with the gasin spaces 13* thereby continuing the process of cooling and condensing the gas in spaces 13*. The gas will travel through the series-of tubes 11* until it reaches approximately the temperature of the incoming gas. It will leave the region 10* by pipe 31* at substantially its original pressure. By this process, after suitable temperatures have been reached and the fractional condensation of the gas is taking place throughout the system and the system is in such condition that practically the only constituent of the liquid inthe botom of separating chamber 1* is nitrogen, compressor 37 may be shut down, valves 9* and 5* closed, valves 22* and 32 opened and part of theliquid nitrogen from the bottom of separating chamber 1* can be removed by pipe 19* to throttle valve 5, where it will be expanded into coil 7* and will leave coil 7* through chamber 8*, passing by pipe 20* to nitrogen chamber 21* where it will exchange its sensible heat with that of the gas in spaces 13*, and will finally lead outof the system at outlet 30*, thereby increasing the heating value of the gas by removing some of the nitrogen.

\Vithout limiting the invention I may say that pressure ranging from 19 to 25 atmospheres, more or less, will beneficially affect the percentage of helium recovered. In the auxiliary cycle generally referred to in the drawings at 4 and 4*, air or nitrogen are equivalents and when nitrogen is referred to in the claims the intentlon is to include air. It may be said that the temperature of the liquid condensate from the liquefy,

' cycle and that the natural gas is lowered by the auxiliary aseous helium is withdrawn at substantially the pressure and temperature of its minimum solubility in the liquid present.

From the foregoing description it is evident that I have provided a method of separation of helium from the liquefied natural gas which eliminates the use of any of the usual forms of fractionating or rectifying columns.employing the use of plates with bubble caps or like devices and providing a definite reflux of the components of highest vapor pressures and that my method of operation as described, is in emphatic con:

tra-distinctio-n tomethods employing usual.

fractioning or rectifying columns or both.

'It will be obvious to those skilled in the art to which the invention relates that modifications may be made in details of construction and arrangement and procedure without departing from the spirit of the invention which is not limited as to those matters or otherwise than as the prior art and the appended claims may require.

I claim;

1. In the recovery of helium from natural gas the improvement in the step of frac-' tionally condensing constituents other than helium of the incoming natural gas by heat exchan e with the outgoing liquid condensate w ich consists in vaporizing the re; spective constituents of the condensate under temperature and pressure conditions substantially like the temperature and pressure conditions under which they were condensed, substantially as described.

2. In the recovery of helium from natural gas the improvement in the step of fractionally'condensing constituents of the incoming natural gas by heat exchange with the outgoing liquid condensate which consists in vaporizing the respective constituents of the condensate under conditions substantially like the conditions under which they were fcondensed, and permitting the outgoing tially as described.

1. The process of recovering helium from natural gas which consists in supplying and expanding a suitable liquid to'establish a region of refrigeration at which helium will not liquefy and from which it is withdrawn at low temperature and at which substantially all other constituents of the gas will leading and in steps condensing a stream of natural gas containing helium under pressure through sald region, and effecting heat exchange between said streamv of gas and liquid constituents by vaporizing the latter in stages at approximately the pressure under which they were condensed, thereby effecting condensation of nearly a like quantityof incoming gas.

5. In the art of recovering helium from natural gas the improved step which consists in effecting heat exchange between the natural gas under pressure and the outgoing liquid by evaporating the liquid at high pressure in alternate stages, and expanding and cooling the gas evaporated from the liquid and applying its sensible heat at in termediate stages.

6. In the recovery of helium from natural gas the improved step which consists in effecting heat exchange between the incoming gas and the outgoing liquid condensate by vaporizing the condensate in stages under temperature and pressure conditions substantially like the temperature and pressure conditions under which it was condensed.

7. In the process for the recovery of helium from natural gas in which the constituents other than helium are condensed and the helium drawn ofi in a region of refrigeration, the improvement which consists in producing the temperature of refrigeration in said region by an auxiliary cycle of liquid nitrogen and in vaporizing the re turning liquid in heat exchange relation with the incoming sup ly of gas at temperatures and pressures substantially identical with the temperatures and pressures at which they were condensed.

8. In the process for the recovery of helium from natural gas in which the constituents other than helium are condensed and the helium drawn off in a region of refrigeration, the improvement which con sists-in producing the temperature of refri eration in said region by an auxiliary cyc e of liquid nitrogen and in fractionally vapor-- izing the returning liquid in heat exchange relation with the incoming supply of gas at temperatures and pressures substantally identical with the temperatures and pressures at which they were condensed.

ARTHUR H. GRAHAM,