US3123982A

US3123982A - Cryogenic gas sampler

Info

Publication number: US3123982A
Authority: US
Publication date: 1964-03-10
Anticipated expiration: 1981-03-10

Description

March 10, 1964 R. M. BROWN ETAL 3, 3, 8

CRYOGENIC GAS SAMPLER Filed Nov. 8, 1960 2 Sheets-Sheet 1 INVENTORS. Wl/AN/V 4 Me MAN/641 ll/brwey: fr I ixaa FIIIIII/l/IIlI/l/llll March 10, 1964 R. M. BROWN ETAL 3,1 8

CRYOGENIC GAS SAMPLER Filed Nov. 8, 1960 2 Sheets-Sheet 2 Wi z A l Brown,

A/farneys fir AfflfCON/S United States Patent 3,123,982 CRYGGENIC GAS SAMPLER Ross M. Brown and Robert C. Emmerling, Manhattan Beach, and Angel R. Florez, Downey, Calif., assignors to The Cosmodyne Corporation, Hawthorne, Calif., a

corporation of California Filed Nov. 8, 196i), Ser. No. 63,031 12 Claims. (Cl. 62-55) Our invention relates to the art of taking samples of liquefied gases such, for example, as nitrogen, oxygen, hydrogen, helium, and others, for analytic purposes; and relates more particularly to a method and device whereby representative samples may be obtained.

As an illustration of the utility of our invention, the greatly increased use of cryogenic fluids for military purposes has created the requirement for control of the purity of these fluids. The principal problem in obtaining satisfactory control has been the lack of a suitable method and device for obtaining and analyzing the fluids without significant alteration of the impurity level, or the introduction of new impurities into the samples taken.

It is an object of our invention to provide a method and device in which the boiling off of any gas from the sample taken is substantially eliminated from the final sample in order that sample enrichment through concentration is minimized or completely eliminated.

It is another object of our invention to provide a method and device whereby a representative sample of liquefied gas may be obtained, in which the flow of fluid from the tank from which the sample is to be taken is employed to lower the temperature of the sampler receptacle and that of the inlet valve and in which the fluid is thereafter flowed as a liquid gas into the sampler receptacle without boil-01f.

It is another object of our invention to provide the method and apparatus as set forth in the preceding paragraph and in which the initial liquefiable gas used to cool the sampler receptacle is isolated from the final liquid sample. This is important since the initial liquefied gas will have a concentration of impurities due to boil-off which occurs in the process of cooling the sampler receptacle because heat is necessarily absorbed by this precooling flow of fluid.

It is also an object of our invention to provide a meth- 0d and device whereby a representative sample of liquefied gas is obtained in liquid form and thereafter vaporized and stored as a gas within the sampler device.

It is a still further object of our invention to provide a method and device as referred to in the preceding paragraph in which, should any boil-off occur in the sampler receptacle, this boil-ofl vapor will flow into the gas storing chamber of the sampler device and will become a part of the sample taken and in this way the sample will be a representative sample without alteration of the impurity level.

Another object of our invention is to provide a sampler device for obtaining representative samples of liquefied gases in which the sampler receptacle which receives the liquefied gas sample is positioned within the gasifying chamber into which the fluid will flow as a gas or liquid and will therein be stored as a gas for later analysis.

It is an object of our invention to provide a method and device of the character referred to in the preceding paragraph in which the operation of obtaining the representative sample is a simple procedure involving merely the opening and the closing of a single valve.

It is also an object of our invention to provide a sampler as referred to in the preceding paragraph in which the device itself indicates when the sampler receptacle has been adequately cooled and the valve to the sampler receptacle should be opened; and also indicates 3,123,982 Patented Mar. 1%, 1%64 when the sampler receptacle is full and when the valve should be closed.

It is a further object of our invention to provide a sampler device as referred to in the preceding paragraph in which the sampler receptacle is enclosed in a pressure vessel and in which the device is enclosed in a light weight separable cover, one part of which, when removed, makes an inlet operating valve accessible and the other part of which, when removed, makes a gas extraction valve accessible. Since the extraction valve is operated by laboratory personnel only, it is desirable that it be inaccessible When the sample is being taken.

It is a still further object of our invention to provide a liquefied gas sampling device that is easy and safe to operate, durable, portable, and that receives an unenriched and pure sample in suficient quantity to be adequate for testing.

Further objects and advantages of the invention may be brought out in the following part of the specification wherein small details have been described for the cornpetence of disclosure, without intending to limit the scope of the invention which is set forth in the appended claims.

Referring to the accompanying drawings which are for illustrative purposes only:

FIG. 1 is a side elevational view of a cryogenic gas sampler according to the invention, shown partially in cross-section, and including its rectangular removably secured housing;

FIG. 2 is a fragmentary cross-sectional view taken as indicated upon the line 22 of FIG. 1;

FIG. 3 is a cross-sectional bottom View of the sampler device taken as indicated upon the line 33 of FIG. 1;

FIG. 4 is a fragmentary cross-sectional plan view taken as indicated upon the line 44 of FIG. 1;

FIG. 5 is a fragmentary cross-sectional view taken upon the line 5-5 of FIG. 1 and illustrating a closure on the cooling line and its relief means; and

FIG. 6 is a fragmentary cross-sectional View taken upon the line 66 of FIG. 1 and illustrating a surge pressure relief means adjacent the extraction valve.

Referring again to the drawings, there is illustrated in FIG. 1 a pressure bottle 11 for retaining a vaporized gas sample, supported on a base frame 12 within a rectangular housing designated generally as 1.3. The housing 13 is comprised of a top section 14 forming a top cornpartment and a bottom section 17 forming a bottom compartment, the two compartments being separated by the base frame 12 which extends between the pressure bottle and the outer walls of the compartments. Each of the compartments are removably secured to the frame member 12 at their adjacent edges by peripherally spaced

screws

18 and 19, respectively. The housing is provided with an unshown handle for carrying and which may be attached to any of the outer walls of the top section ltd.

A sampler receptacle generally designated as 20 is supported within pressure bottle 11 and is comprised of a cup 23 forming a sampler chamber therein. The support means for the sampler receptacle include a disc shaped top 24, as shown in FIG. 4, and which in turn is supported by a tubular member 25, having its lower end threadedly engaged in a tapped opening 26 in the top 24 and having its upper end supported on a mounting flange 2.9 which is scalingly secured in the top of bottle 11.

Surrounding the cup 23 is a cooling shield 30 forming a cooling jacket 31 between the walls of the cup and the shield. The cup is sealed along the inner face of its Wall where it enters the top 24 by means of brazing ring 32 and the shield is similarly sealed externally by brazing ring 35.

An inlet or fill means generally designated as 36 extends through a mounting fixture 37 welded to the shell of bottle 11 and has on its outer end a threaded fitting 38 for connection to a tank containing a liquefied gas from which a sample is to be taken. When the fitting 38 is not so connected to take a sample, a closure 41 is threadedly engaged therewith as shown in FIG. 1.

Extending inwardly from inlet 36 into the bottle 11 is a tube 42,, shown in FIGS. 1 and 4, threadedly and sealingly engaged in a passage 43 in disc 24. Inwardly of its threaded portion tube 42 extends through an opening 44 in the wall of shield 36 in which it is sealingly engaged and its inner end abuts the outer wall surface of cup 23 in a sealed relationship, outwardly of opening 47 in the latter wall which is in alignment with passage 43.

Passage 43 provides the inlet for cup 23 and is sealed therefrom by a sample obtaining valve 43 shown closed on seat 49. When valve 48 is lifted off its seat passage 43 is connected to the cup by passage 50 extending downwardly from the valve seat.

Passage 43 is also connected to an annular recess 53, provided to permit the liquefied gas to cool the mass of the valve, and the annular recess 53 is in turn connected to a passage 54, shown in FIGS. 2 and 4, which connects the inlet 36 to the cooling jacket 31.

Shown opposite the inlet in FIG. 1 is an outlet or drain generally designated as 55 having a fixture 56 sealingly welded in the shell ll. Extending outwardly of the fixture 56 is a threaded end portion 59 on which there is a closure 66 threacledly engaged, as shown, when the device is not connected to receive a sample. As best seen in FIGS. 1 and 5, closure cap 66 has a threaded opening in its outer end in which is threadedly engaged a flexible mushroomshaped plug 61 having its lips 62 resiliently engaged on the outer surface of the cap. A passage 63 through the center of plug 61 connects the outlet 56 with the under surface of the lips 62 so that an excessive pressure within drain 55 is bled off through passage 63 and under lips 62.

Outlet fixture 56 is joined to the cooling jacket 31 by tube 64 which has its inner end threadedly engaged in top 24, the said end extending into an opening 65 in the wall of shield 30 in which it is sealingly engaged.

The valve 48, which is hand operated to obtain a liquefied gas sample, has a stem 66, as shown in 'FIGS. 1 and 2, slidably and sealingly engaged in support tube 25. Threadedly engaged in the outer end 69 of the stem is a spring holding pin 70 having a head 71 on its outer end. In abutment with the inner surface of head 71 and surrounding the pin is a washer 72 and spaced between washer 72 and the upper end 69 of the stem, surrounding the pin, is a valve adjusting coil spring '75.

The valve handle 76, which is exposed and accessible along with inlet 36 and outlet 55 when the top section 14 v is removed, is fixedly threaded to the external threads of a nipple 77, which is in turn rotatably threadedly engaged with the outer end 78 of tubular support member 25. In the outer end of the handle is a threaded central bore 79. To position the valve 43, after the handle is in closed position on tube 25, the valve is inserted through the bore 79, into tube 25, and placed on its seat 49. A plug 86, having a central inwardly opening recess Si, is then threaded ly engaged in bore 79 to abut washer 72, the head 71 extending into and being spaced from the inner surfaces of the recess 81. With the handle 76 in the closed position, the plug it is tightened against the force of the spring with a special wrench inserted into recesses 32 in the top of the plug to pre-set the valve. That is, the valve is pressure-tested and the plug and spring are adjusted until the valve lifts at the desired pressure against the force of the spring, causing the head 71 to be moved off the washer and inwardly into recess 81. When the handle is rotated for opening, along with its fixed nipple 77 on threaded end 78, it is raised outwardly so as to raise plug 80 and permit the washer to lift and the valve to be unseated.

As best seen in FIGS. '2 and 4, the cup 23 is vented to the pressure bottle ill by means of a passage 83 extending upwardly from the cup into the top 24 and by means 4 of an extension of the passage in the form of a vent tube 84 which is threadedly engaged in the top and extends upwardly into the bottle. This venting means permits the gas sample collected in the liquefied form to vaporize and expand into the gas bottle from which it is extracted to test the collected sample.

As best seen in FIGS. 1, 3, and 6, at the other end of the bottle 11 is a gas extraction valve housing designated generally as 86, separated from the upper portions of the bottle by frame plate 12 when the two housing members are as shown in FIG. 1 and being accessible when the lower housing member 17 is removed by withdrawal of the screws 19. The valve housing is connected to the bottle by means of a mounting nipple 87 sealingly secured in the bottom of the bottle and by means of a T-fitting 83, which is threadedly engaged in the valve housing and at 90 thereto, has a small diameter portion of the fitting 87 threadedly engaged therein. Passage 89, as best seen in FIGS. 3 and 6, connects the bottle to passage 89a, the end of which forms valve seat 8% for valve 91. The valve 91 is lifted off its seat by pressure in the bottle 11 or by a spring 91a, acting on stem disc 91!), when valve handle 9% is rotated to release the latter. When the valve is open, passage 89 is connected through the valve to discharge outlet 92 which extends into the extraction fitting 93 from which the gas is taken for testing. When the device is not in operation the extraction fitting is sealingly closed by a threaded cap 94.

Threadedly engaged at the other end of the T-fitting 88 is a nipple 95 having a passage 97 therein, connected at all times to passage 89 in the bottle. At the end of passage 97, as best seen in FIG. 6, there is a blowout disc 98, sealingly secured in position by plug 99 in an open end of the nipple 95. Safety disc is designed to burst at a predetermined pressure which may be developed suddenly within the bottle 11 in the event of excessive heating, for example.

In operation, to obtain a representative sample of a liquefied gas from a producing plant or a storage tank, the housing 13 is placed upright, as shown in FIG. 1, and the upper portion 14 is removed therefrom. At this time the

valves

48 and 91 will have been closed in that the bottle 11 and sampler cup 23 will have been evacuated either in manufacture or after a previous extraction of a sample of gas through the valve 91.

The fitting 38 is connected to the tank from which a sample is to be taken after the

closures

41 and 60 have been removed. A valve in the line connected to the fitting 38 is then opened so as to permit the flow of liquefied gas into the tubular passage 43 around the mass of the valve 48, into the passage 54, as shown in FIG. 4, and then into the jacket 31 formed by the cup 23 and the shield 36. For a very short time the liquefied gas entering the jacket 31 will tend to vaporize and flow out of the passage 64 in the outlet 55 but the cooling occurs so quickly that the flow of vaporized gas may not be perceptible. In other Words, when the cup is cooled to a degree at which boil-off ceases, liquefied gas will start to flow out of the outlet 55.

As a result of this cooling, no further vaporization or boiling off of the liquid will occur between the inlet 36 and the outlet 55'. This is an important feature of the invention because when boil-off occurs a liquefied gas becomes enriched with impurities as the impurities in the gas are less volatile than the pure gas. Thus, since there will be no further boil-off between the inlet and outlet on opposite sides of the bottle 11, a representative sample from the source externally of the bottle can be taken from the fiow path between the said inlet and outlet. In other words, there will be no boil-off from the sample that will be allowed to flow into the cup 23 after the latter has been properly cooled. Further, the initial cooling gas, by virtue of the closed valve 43, is isolated from the final liquid sample allowed to enter the cup and this is important, not only because of the concentration of impurities in the boil-off in the initial gas, but because in addition, it may have acquired contaminants from the line prior to reaching the sampler.

After the cooling has been accomplished and the jacket 31 and the tubes 42 and 64 are filled with the flow of liquefied gas, the valve handle 76 is rotated to open the valve 43 to permit the liquefied gas to flow into the receptacle 23. Upon turning the handle 76 the lower surface of the plug 80 moves upwardly from the washer 72 so that the sealing force of the spring 75 is removed from the valve, and after further rotation, the nipple 77 in the handle makes positive contact with the lower surface of the washer to definitely cause the valve to be lifted off its seat. The liquid then enters the receptacle through the short passage 54) directly below the valve seat and the flow of the liquid out of the tubes 64 of the outlet will tend to stop. However, as soon as the receptacle is filled, and this occurs rapidly, the liquefied gas will again flow through passage 54, the upper portion of the jacket 31, and out of the passage 64. Thus, when it is visibly observed that the liquefied gas is again flowing out of the outlet 55 it is realized that the cup is filled and the valve can be closed. While the recurrence of the fiow out of the outlet 55 is a positive indication that the receptacle 23 is filled, from experience it has been determined in one design of the invention, for example, that when the valve is rotated four turns to open it, by the time the fourth turn has been completed the receptacle 23 is then filled and the valve may be immediately closed. Since the vent tube 84 is open to the interior of the bottle 11 at a considerably higher level than the top of the jacket and the outlet, no liquefied gas will flow out of the top of the vent.

After the valve 48 is closed the valve of the tank from which a sample is taken is then closed and the fittings removed from the inlet 38.

Closures

41 and 60 are then threadedly engaged with the

fittings

38 and 59, respectively, and the housing top 14 is secured to the frame member 12 by screws 18.

As the gas warms it will tend to vaporize and flow from the receptacle cup 23 out of the vent 84 into the bottle 11. In the event the pressure in the bottle and the cup increases to a predetermined amount greater than the force exerted by the spring 75, the valve will be lifted off its seat, forcing the pin head 71 upwardly in the recess 82, so as to permit fluid to flow through passage 56 into passage 54 and through the outlet 55 into the passage 63 in the mushroom shaped plug 61. As long as the pressure is just slightly greater than that of the downward force of the spring there will tend to be a leak through passage 63 and out under the lips 62 of the plug. This, of course, occurs only during unusual circumstances and this type of leak-off is provided only as a safety measure. Similarly, if there should be a sudden surge of pressure greater than that required to blow out the safety blow out disc 98, the said disc will burst to reduce the pressure.

Generally, after a simple has been taken the housed device is shipped or carried to a laboratory where the sample may be tested. To accomplish the testing the housing portion 17 is removed by the withdrawal of screws 19 and extraction lines are connected to fitting 93 after cap 94 has been removed. Valve 91 is then opened by the rotation of the handle 9% and the sample of gas is permitted to be extracted from the bottle and the cup. As previously indicated, after the test sample has been extracted the sampler receptacle 23 and the bottle 11 are evacuated so as to remove all possible contaminants for the next sampling operation. Thus, before the extraction line is removed from fitting 93, valve 91 is closed and then the bottle and sampler receptacle are completely sealed. At this time the housing portion 17 is again secured to the frame member 12.

From the foregoing, it is clear that other forms of the device and method disclosed herein may be used without departing from the principle of the present invention whereby a truly representative sample of a liquefied gas may be obtained for testing.

We claim:

1. In a cryogenic sampler: a sampler receptacle; a pressure vessel surrounding said receptacle; an inlet to said receptacle extending from the exterior of said vessel and being controlled by a valve, said valve being operable from the exterior of said vessel; heat exchanger means on said receptacle connected to said inlet upstream of said valve; an outlet from said heat exchanger means extending outwardly of said vessel; and a vent from said receptacle to said vessel.

2. In a cryogenic sampler: a sampler receptacle; a pressure vessel surrounding said receptacle; an inlet to said receptacle extending from the exterior of said vessel and being controlled by a valve, said valve being operable from the exterior of said vessel; heat exchanger means on said receptacle connected to said inlet upstream of said valve; an outlet from said heat exchanger means extending outwardly of said vessel; a vent from said receptacle to said vessel; and an extraction valve for controlling a conduit to said vessel.

3. In a cryogenic sampler: a sampler receptacle having a valve controlled inlet; a pressure vessel surrounding said receptacle, said inlet to said receptacle extending from the exterior of said vessel, said valve being operable from the exterior of said "essel; a cooling jacket surrounding a substantial portion of said receptacle connected to said inlet upstream of said inlet valve; an outlet from said cooling jacket extending outwardly of said vessel; a vent from said receptacle to said vessel; an extraction valve externally of said vessel for controlling a conduit extending therefrom; and a cover for said pressure vessel comprising two parts, said parts being separately attachable and removable from said vessel, one of said parts enclosing said inlet valve and said inlet and outlet, the other of said parts enclosing said extraction valve.

4. A method of obtaining a representative sample of a liquifiable gas from a tank comprising: flowing a liquefied gas, from a tank from which a sample is to be taken, adjacent to and isolated from a sampler receptacle to lower the temperature of the receptacle to a degree to minimize boil-off; flowing said liquefied gas from adjacent said receptacle to the atmosphere to indicate when the temperature of the receptacle has been lowered to the degree at which boil-off is minimized; and thereafter continuing said flow of said liquefied gas causing said gas to flow into said receptacle.

5. A method of obtaining a representative sample of a liquefiable gas from a tank comprising: flowing a liquefied gas, from a tank from which a sample is to be taken, adjacent to and isolated from a sampler receptacle to lower the temperature of the receptacle to a degree to minimize boil-off; thereafter causing said gas in liquefied form to flow into said receptacle; and flowing said sample from said receptacle into a gasifying chamber.

6. The method of obtaining a representative sample of a liquefiable gas from a tank comprising: flowing a liquefied gas, from a tank from which a sample is to be taken, adjacent to and isolated from a sampler receptacle to lower the temperature of the receptacle to approximately that of said gas until the fluid flowing from the adjacency of said sampler receptacle is in liquid form; and thereafter continuing said flow of said liquified gas causing said gas in liquefied form to flow into said receptacle.

7. The method of obtaining a representative sample of a liquefiable gas from a tank comprising: flowing liquefied gas, from a tank from which a sample is to be taken, adjacent a sampler receptacle to lower the temperature of the receptacle until the fluid flowing from the adjacency of said receptacle is in liquid form; continuing said flow of said liquefied gas causing said gas in liquefied form to flow into said receptacle; and isolating said sample of liquefied gas in said sampler receptacle.

8. The method of obtaining a representative sample of a liqueflable gas from a tank comprising: flowing liquefied gas, from a tank from which a sample is to be taken, adjacent a sample receptacle to lower the temperature of the receptacle until the fluid flowing from the adjacency of said receptacle is in liquid form; causing said gas in liquefied form to flow into said receptacle; isolating said sample of liquefied gas in said sampler receptacle; and flowing said sample directly into a gasifying chamber.

9. In a cryogenic sampler: a sampler receptacle; a gas inlet to said receptacle controlled by a valve; and heat exchanger means on said receptacle connected to said inlet upstream of said valve, said heat exchanger means being in communication with said receptacle when said valve is open.

10. In a cryogenic sampler: a sampler receptacle; a gas inlet to said receptacle controlled by a valve; first heat exchanger means on said receptacle being in communication with said receptacle when said valve is open; and second heat exchanger means in communication with said first heat exchanger means to cool the mass of said valve controlling said inlet.

11. In a cryogenic sampler: a sampler receptacle; a gas inlet to said receptacle controlled by a valve; heat exchanger means on said receptacle; and a common gas supply line to said receptacle inlet and to an inlet to said heat exchanger means, said heat exchanger means being in communication with said receptacle when said valve is open.

12. In a cryogenic sampler: a sampler receptacle; a pressure vessel adjacent said receptacle; an inlet to said receptacle being controlled by a valve; heat exchanger means on said receptacle connected to said inlet upstream of said valve; an outlet from said heat exchanger means; and vent means from said receptacle to said vessel.

References Cited in the file of this patent UNITED STATES PATENTS 1,998,629 Lagarde Apr. 23, 1935 2,882,694 Vander Arend et a1. Apr. 21, 1959 2,966,040 Henry cc. 27, 1960 2,976,695 Meade Mar. 28, 1961 FOREIGN PATENTS 728,134 Germany NOV. 20, 1942 OTHER REFERENCES

Claims

6. THE METHOD OF OBTAINING A REPRESENTATIVE SAMPLE OF A LIQUEFIED GAS FROM A TANK COMPRISING: FLOWING A LIQUEFIED GAS, FROM A TANK FROM WHICH A SAMPLE IS TO BE TAKEN, ADJACENT TO AND ISOLATED FROM A SAMPLER RECEPTACLE TO LOWER THE TEMPERATURE OF THE RECEPTACLE TO APPROXIMATELY THAT OF SAID GAS UNTIL THE FLUID FLOWING FROM THE ADJACENCY OF SAID SAMPLER RECEPTACLE IS IN LIQUID FORM;