US2516934A - Gas generator - Google Patents

Description

E. R. WEAVER GAS GENERATOR Aug. 1, 195o ATTORNEY 4i 41 M i@ 1. L RM fa.. (4 m@ E L L we V. F.. E. mE M W5. M W n. l. :L T. o WSNS. M 5, n w. A M l F Tamm 4: 4J f a7n-. .M w. L@ L 4,

Patented Aug. 1, 1950 UNITED STATES PATENT OFFICE GAS GENERATOR Elmer R. Weaver, Chevy Chase, Md.

Application November 5, 1947, Serial No. 784,211

Y 9 claims. (Cl. :a3- 281) (Granted under `the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 1 The invention described herein may be manufactured and used by or for the Goverment of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467),

This invention relates to a hydrogen generator and more particularly to a hydrogen generator for inilating a balloon at sea.

Lifeboats and rafts for use in case of a disaster at sea vare frequently provided with small radio transmitters for signalling for aid and for guiding rescuers to the survivors. One method of raising an antenna for such a transmitter is by a balloon, which must be inflated after the disaster.

It is therefore desirable to provide, along with the transmitter and balloon, a, suitable hydrogen generator for inating the balloon. Hydrogen may be prepared by reacting any of a number of reagents with water. Among the reagents having the most desirable characteristics for this purpose are lithium hydride, sodium hydride and calcium hydride.' In time of war, when hydrogen generators of the type disclosed are the most in demand, sodium hydride is the reagent most likely to be available in sui'lcient quantities. The generator described herein, while advantageous for use with other reagents, is particularly advantageous for use with sodium hydride.

Sodium hydride is so active that only a small area of contact is necessary to produce gas at a high rate, particularly during the early stages of the reaction. The generation of the hydrogen is' accompanied by the production of a considerable amount of heat which under certain circumstances could ignite an explosive or cornbustible mixture of hydrogen and air, Since the generator is designed to be carried on ships and aircraft, it is necessary to insure that accidental contact of water and the sodium hydride does not occur. v

` When the sodium hydride is purposely brought in contact with 'water to innate the balloon, the balloon must be protected from the heat generated. There are two reasons for cooling the hydrogen as much as possible. High temperature greatly affects the strength of thin rubber balloons, and the steam which necessarily accompanies the hot hydrogen considerably reduces its lifting power. Protection of the rubber against the high temperature is much the more important reason.

Particularly at the beginning of inilation it is diicult to prevent the balloon from folding over the end of the delivery tube so that the stream of emerging gas impinges directly on some part of the balloon. The relative resistance of a balloon to bursting and tearing depends on the strength of the weakest part in the same manner that the strength of a chain is that of its weakest link. Hence the overheating of even a very small area of the balloon during inilation is highly important.

'I'he rate of inflation of the balloon is limited by the practicability vof controlling the temperature of the liberated hydrogen. The damage done to the balloon is likely to depend more on maximum temperature than on an average temperature -and a high temperature at the beginning of ination, when the rate of evolution tends to be the greatest, is particularly damaging. Hence if time is to be saved in getting the balloon into the air a uniform rate of hydrogen production is important.

The sodium hydride used in the generator may be combined with oil to aid in controlling the reactivity of, and serve asa binder for, the sodium hydride. Since this oil will quickly dez' stroy the balloon if it reaches it, the entrainment of the oil in the hydrogen delivered to the balloon must be avoided with certainty.

It is an object of this invention to provide a hydrogen generator the reagent of which is protected from accidental contact by outside moisture.

It is another object of this invention to provide a hydrogen generator with means for suitably cooling generated hydrogen.

It is an object of this invention to produce a. hydrogen generator with means for excluding water from the hydrogen produced.

It is another object of this invention to provide a hydrogen generator with means for excluding oil from the hydrogen produced It is also an object of this invention to provide a. hydrogen generator with means for automatically controlling the rate at which the hydrogen is produced.

These and other objects will become apparent from the following specication taken in connection with the accompanying drawing in which:

Fig. 1 is an elevation view of the hydrogen generator assembled and ready for use.

Fig. 2 is a, detailed elevation View in section oi the hydrogen generator.

Fig. 3 is an alternate inlet pipe V which vmay be used with this generator.

down nearly to lower outer end wall 4b. The

,` further be seen that auxiliary end Wall Ic, annulower extending part of side wall I forms skirt 22. Ib and is joined to auxiliary end'wall lc.

outer wall t at a level near auxiliary end. wall Ic.

Inner wall I extends upward past end wall` An'-' nular wall Ia extends between inner-wall I andof inner side wall I between upper end wall Ib and auxiliary end wall Ic.

It will be seen that the generator is thus provided with an outer sealed shell impervious to the entry of Water, said outer shell consisting of side wall II, end walls 4ay and 4b and frangible diavphragms 5 and 3.1 Theygeneratoris also lprovided with an inner'sealed shell impervious to the entry of water consisting of side wall l, end walls Ib and 2 and frangible diaphragms -5 and 'I. It will lar member Ia, and baille member I5 taken with Cylindrical baille member I5 is attached `to said annular wall Ia and extends downwardly therefrom between inner wall I and outer wall 2.

I holes I4 provide a bell member under which gas 4may escapefrom central tube 3 through holes I2 and eventually into upper chamber D as will be explained more in detail below.

Outlet tube Il! is provided, the bottom part of which is internally` threaded and is adapted to be Central cylindrical tube 3 extends through end walls llaa,v Ic, Ib, 2 and 4b and extends slightly past upper wallr la and lower wall 4b, screw threads 3a and 3b being placed on the outside of the upper and lower protruding ends, respec-l tively. Inner side wall I isiastened and sealed, as by solder, to end walls Ib, lIc andZ. 4Outer side wall 4 is also sealed to end walls 4a and 4b. Central tube 3 is sealed to end wallsU Ila,"'Ic,- `Ib, Zanddb.

Between upper end wall 4a and' auxiliary end wall Ic is formed a gas chamber D. ABetween auxiliary wall Icv and upperend wall 'Ib is formed a filter chamber C which is mostly filled with a lter substance I3 whichmay bev glass wool." Between central tube'3, inner side wall AI, upper end wall Ib and lower end wallV 2 is a reagent 'chamber A which is filled with al reagent, 'such as sodium hydride, adapted to producev hydrogen on reaction with seawater. Between' lower end walls 2 and 4b andside walls I and 4 is a water chamber B.

A rstl set of holes I'I and lower set of: holes 26v form a firstgroup of holes communicating from-the interior of central tube 3 to upper gas chamber D. A second group of holes I2 communicate from the `interior of central tube 3 to the filter chamber C; A third group of holes consisting of a largenumber -of relatively closely spaced holes I I communicate from the interior of central Vtube 3 with reagent chamber A. A fourth group of holes 2l communicate from .the interior of central tube 3 with water chamber B.

Central tube 3 has at the lower and upper ends thereof frangible diaphragms 5 andl 8, respece tively. There is also awfrangiblediaphragm 'I between holes Ily and holes II and yanother fragible diaphragm 6 between holes II and holes 2 I. There is a permanent diaphragm 'la between holes 26, andholes I2. Slightly below frangible diaphragm `8 is an annular valve seat 24a. Below seat 24a is a ball float 24` which is maintainedsin a position slightly under seat. 24amby :a pin25 which extends through central tube 3.4

Holes I6 are provided in the outer fperiphery of annular member I5a, communicating-from upper chamberv D to the space 4betweenbaille member I5 and outer wall Il. Holes 23 are also provided in the upper portion` of skirt 22.v` Between skirt 22 and the outer periphery of lower conical end wall 2 is placed anannularlmember 2 Iof,a substance which is pervious to air but, when wet, impervious to the,passage of oil. Member 21 may '.befa coarsely porous paper such .asunrnpregnated roofing felt. I'Iljiemen'iber" 21 .covers the holes 23. A series of holes I4 are placedintheupper' part screwed onto the upper protruding end of central tube 3. The lower portion of outlet tube II! is of a relatively large diameter and houses a trapi21 consisting of an innertube 21a of relatively small diameter mounted concentrically.' with tube yI Il. The 'bottompart of tube 21a has an outwardly extending ange whichis yfastened and sealed1at its outer periphery to'the tubel Il.` The upper end of tube 2laf-isgsealed to, andcovered by,- adisklike member 2lb which has a kdownwardly extending ange. The upperportion ofy tube 21a contains holes Z'Icv which are under the rdownwardly extending flange-of member 2lb.

Theupper part I3 of delivery tube I0y is lof a relatively small diameter and it is adapted to re? ceive thereover thel neck of the balloon to be inflated. Portion I9V oi deliveryy tube I0 contains holes IQa for the egress of gas. The upper end of l portion YIt of outlet tube; IIJ is vinternally threaded -to `receive in` threadedengagement .therewith the intermediate threads Ztay of a bayonet member `20. lBayonet member-20 when .screwed into delivery. tube It!` by threads Zllql extends throughout the length lof the .portion i outlet tube ID... Bayonet member 2Q also has screw threads -ZIlbat the end remote from the point. 1

Hence bayonet member may have its threads 20adisengaged from outletv tube Ill and the bayonet 20y may be reconnected with outlet tube IU by threads 2Gb. The diameter of the restricted portion I9 and the diameter of .bayonet ZI! are such that both members may be `thrust into central tube 3. The combined .length of the portion I9 andthe bayonet 2il=must be such that the bayonet when thrust through the bottom end of lcentraltube 3 will pierce theVfra'ngible dia-- phragm-f'l. f v An inlet tube y9 is .provided for. attachment.` to the screw threads 3bon the lowerprotruding end ofthe -central tube 3. Caps, not'shown, maybe provided for attachment to the Vupper andlower endsrespectively, ofthe central tube 3 when outlet tube I0 and inlet tube y9 are not in place. The `caps are to protect frangible diaphragms '8 -and 5,ltfspectivelyj When Vthe generator isin storagegbayonet 9 is attached to outletv tube Illv with the shaftand point of the .bayonet extending `down into". the portio'nllt of the outlet tube. Outlet tube I0 and inlet tube 3 are both detached from the generator andthe .protective caps arescrewed on. vThis reduces the'space necessaryr for storing the generator when it` isawaiting use., v

When the generator is to be used, the ,protective caps` are unscrewed and discarded. The threads 29a of bayonet. 20'are disengaeedQfroxn .5. the corresponding threads in outlet tube I0. `The bayonet is turned end for end and rescrewed to `outlet tube 4Il'I vby meansY yof endthreads 20h. BayonetZU and the restricted portion `I il` of outlet tube IIJ are then'thrust upwardly through the `bottom end of central tube 3 piercing frangible diaphragme 5, 6 and 'I. Bayonet '2 0 ,is then used to pierceV frangible diaphragm Band is unscrewed `from out-let tube l!) and discarded... t' t Outlettube I Il is now screwedfto .the upper end `of central tube 3 by means of screw threads4 `3a 4and inlet tube 9 `is screwed `to the lower end of central tube 3 by means of screw threads 3b. 'I'he neck of the balloon to be inated is pulled over the restricted `portion I9 of outlet tube4 I0. The entire generator is thrust in the water. to approximately the water surface level a.` The generator wil-l then automatically deliver .hydrogen to the balloon at a uniform rate. t t

When the `generator is immersed in water, the surface of which is at the level. @hydrogen is steadily produced. Within the space between the inner and outer shells, the water will stand at some level b which is-lower than level a by the pressure required tc force-the hydrogen through openings 'I5 and'. I lytvalve l8r, and ioutlet tube I9 plus the back pressureof` the balloon.

f .I Since hydrogenbubbles out from under baille member I5 at level; c,the pressure atthat point is` common to bothyvater and fgas..4 Neglecting the very smallA pressure required 4 to4b force water through openings II and fractured diaphragm 6 `into the reagentchamber Aat the .rate at which it reacts, level d ofthe water in chamber-A must be belowlevel c by the amountof pressure required to force the hydrogen throughthe openings l I, l2,.lter I3 and openings I4. ,The steady or` average rate ofproduction of, hydrogen is simplythe `rate at which hydrogen .will flow from the rate again fallsgback-to` normal. yHence the l production of hydrogen at -anearly constantrate is centrolled A automatically .and is; entirely independent of theimmrsionof the generator until `level .b at `which water 1standsllaetweein theinner yand outer shell becomes lowerA than the bottom bf the bane member 15, ',.I"i'l'th1 s'geursjthe hyclrai'ulic'` head on the generater becomes the difference between the levelsfb-djin ead of the difference' between the levels c cl." f The sodium hydrideis so `activeA that'nly a small area f contact between it'and the lwater is "necessary to produce gas atta high'rate." Hence 4a' small increasein' -the level dres-ults in alar'ge `i`ricre`asein the rateof` producton'fTheleveld *may be expected to remain f arlyconstant andthe beginning torend. l Y Y The condition most 'likely tov cause a's'erious change in the production rate in any hydraulically controlled'generator, especially with a scum forming reagent like' sodi'un'i"'-hx'dridef and oilgis the partial stoppage of tlcontroliing orices. In

rate of reaction correspondi ly'lcon'stant from this 'generator the csntrbllingerineesarerparticularly wel-1 protected@ Watrcannot rise in the generating chamber lAabove` level f: which leaves a relatively large space for the ibreaking of foam and dropping of spray. t

The gas enters the central tube through relatively small holes -II with a change of direction and velocity both favorable to the dropping of spray. There is another change of direction and velocity at the openings I2 into the lter chamber C so that very little liquid should reach the filter I3. A relatively large volume is available for the lter I3 so that it can be made eiective and still loose enough to offer very little resistance to flow in comparison with the orifices I4. Practice has shown that some liquid reaches the filter material but that none of it penetrates to the orifices I4. Y Y e' The purpose of the conical end wall 2 is to provide gradual access of water to the hydride when the generator is rst submerged and to insure prompt drainage of excess water when rthe rate of reaction becomes too high.

The generator may be made shorter and of greater diameter-than the proportions shownin Fig. 1 of the drawing with the object of conserving weight. However, such modified construction limits more closely the depth of immersion possible without causing 4water to enter the top of the generator through holes I2 and makes deeper submersion necessary if pressure in the balloon forces Water out of the generator before the reaction is complete. One factor that tends to slowdown the rate of hydrogen production toward the end of the reaction is the accumulation of sodium hydroxide and Voil in the generator'. At the beginning of the reaction the column of hydride rests on inner end wall 2 and rising liquid cornes into contact with as much of its lateral surfaces as is neces sary to maintain the constant rate of reaction automatically. Toward the end of the reaction the remaining solid hydride, immersed in oil and partially supported by bubbles of hydrogen at its under surface, iioats on a solutio-n of strong sodium hydroxide ofhigh density and relatively low reactivity. During this stage the hydraulic levels no longer automatically control the rate of reaction which becomes merely the `rate lat which floating oily fragments ofthe solid react `with a concentrated alkali.

The rate would be no longer under automatic control andthe last stages of the reaction considerably hastened if the hydroxide solution could be drained away as formed and replaced with fresh water. This is possible if a double inlet tube 9a shown in Figs. 3 and 4 is substituted for the simple inlet tube '9 shown in Fig. 2. The alternate inlet tube 9a includes an inner tube 9b held concentrically within the outer tube by spacing members 9c. The inner tube 9b is longer than the outer tube and protrudes therefrom at each end. I n the use of the alternate inlet tube 9a`, diaphragm 6 must be substantially completely removed and the inner tube 9b of the alternate `inlet tube 9a must extend above the rst few holes II leadingy into the reactionchamber A. A slow but steady flow of heavy hydroxide solution idownward in theV outer tube and of fresh Water upward in the upper tube willv occur when the in- )let tube ofFig. 3 is used. l

The oil, which must be prevented from reaching the balcon, is lighter than water and is mostly retained in the reaction chamber A from which its escape with the hydrogen is prevented by the Vmeans already described for keeping the filter I3 clear. However,` the escape of the oil intothe Waterbetween theinner and outershellsrfrom which it might be picked up and carried on into the balloon requires other Vpreventative means. In the generator as shown in Fig. 2, oil may usually ilow through openings i l and 2l into the water chamber B. One means of preventing any oil in chamber B from being carried into the balloon is the trap formed by skirt 22 and porous paper means-2?. rThe porous paper 2l will pass air but, after being wet with water, will not pass oil.

A second alternate inlet tube, not shown, might also be used to prevent oil from entering the chamber B. For this purpose the upper end of the inner tube would only have to be seated against the edge of the perforated diaphragm G. This, of course, would prevent the use of the double tube for draining off caustic solution as previously described. Y

Another means for keeping oil and water out of the balloon is the float valve I8 at the outlet of the generator. The ball iloat 24 may be a sphere of plastic and should be about half as heavy as water to prevent the possibility of its being held in place by gas pressure. When water enters the valve through openings 26, the ball rises but hydrogen continues to escape until the ball Eil seats against member 2da. y Water cannotV enter the large chamber D very rapidly-beu rcause of the resistance to flow of orices IS, lhence the closing of the valve `will be very slow and should result in a gradual increase of pressure which will tend to force the water out of chambers D and B. When the water leaves the chamber D the ball will again fall and gas will start to ilow.

To prevent any remains of the film of water formed by opening and closing of the valve I3 from reaching the balloon, trap 21 is employed. Any droplets of water turned downward with the hydrogen at the trap will continue downward and remain at the bottom of outlet tube Il), the capacity of which is greater than any volume of water which can possibly reach this point.

The provision of two water-impervious sealed shells surrounding the sodium hydride adds materially to the safety of the generator since accidental puncturing of the outer shell does not allow outside moisture to come in contact with the hydride. The entire generator, because of its small size, and because of its construction with a central tube attached to all of the end walls through which it passes, allows a strong construction with light Weight.- The chamber B might be filled with carbon dioxide at the time of `manufacture of the generator which would give at least some protection against ignition in case both inner and outer shells were punctured by an unusually severe mishap. The carbon dioxide could be inserted by dropping a small piece of solid carbon dioxide into the generator during the last stage of assembly and sealing the last frangible diaphragm 5 or 8 after the solid carbon ldioxide had evaporated.

It will be understood that this generator may be advantageously used to produce other gases than hydrogen, with other reagents than the sodium hydride herein described, and for other uses than to inflate balloons. The structures above described are by way of example only land many changes and modications of this inven- Vtion will occur to those skilled in the art within the scope of the appended claims.

What is claimed is:

1. In combination an outer enclosing vessel :provided with top and bottom openings, an inner closedvessel spaced from the top and bottom walls of the outer vessel. and concentrcally spaced from the side .walls thereof, likewise provided with alignedtop and bottom openings,y a tube passing throughand sealed in said openings, a dependent partition in the annular space between the vessels dividing the upper portion of said space into two annular spaces, and a top closure for said space, said inner vessel being horizontally dividedinto upper and lower chambers through which said tube extends, said tube being provided With a bottom opening into said outer vessel below the bottom of said inner vessel, intermediate openings into ythe lower chamber of said inner vessel, an' opening into the upper chamber thereof, and an opening into the space between the covering walls of said vessels above the inner vessel, a diaphragmv blocking said tube between said two last-mentioned openings, said upper chamber having an openingv into the inner annular space provided by the deloel'ldingV wall, said top closure having an opening between the outer annular space and the space between said covering walls. y

2. kThe combination of claim l, in which frangible diaphragme blockysaid tube, one being at either end, one being between the bottom opening and the intermediate openings, and one being between said intermediate openingsand the tube opening intosaid upper chamber.

3. The combination of claim 1, in which lter material is provided in the upper chamber of the inner vessel.

4. The combination of claim 1, in which a oat valve -is placed in said tuber above the tube opening into the space between the coveringwalls of said vessels above the inner vessel.

5. The `combination of claim' 1 in which the bottom walll of said inner vessel slopes toward the outer vessel as it approaches the 'tube and in which there is at least one hole in said tube communicating with the space within said inner vessel adjacent the point Where said bottom wall is connected to said tube.

6. The combination of claim 1, in which there is additionally included a first frangible diaphragm between said bottom opening and the ad'- jacent end of the tube, a second frangible diaphragm between said bottom opening and said intermediate openings,k a third frangible diaphragm between saidintermediate' openings' and theopening into said upper chamber, a fourth frangible diaphragm adjacent the top of said tube and in which a delivery tube is provided adapted for detaehableconnection with the top end of said tube, a `pointed .puncturing member detach-- ably connected to said delivery tube with its point inside said delivery tube, said puncturing member beingA also adapted Vto be detachably connected to said` delivery tube with the point outside said delivery tube, whereby in said last condition the combined length of said delivery tube and said puncturing member will permit said third frangible diaphragm to be punctured from the bottom end of said tube.

7. The combination of claim 1, in which the lower chamber of the kinneryessel is `lled with sodium hydride.

8.` The combination of claim` 1, in which an inner tube concentric with and inside said firstmentioned tube is provided, kextending past said bottom openingy insaidfrst-mentioned tube and also extending past at least one of the intermediate holes in. said inst-mentioned tube.

9. The combination of claim 1, in which the REFERENCES CITED 51de Wan of SmdnPer Vessel extenqs past tf'he The following references are of record in the bottom Wall of said mner vessel forming a skirt, fue of this patent: there being holes in said skirt adjacent to and ber low the bottom Wall of said inner Vessel, said 5 UNITED STAFES PATENTS holes in said skirt being covered by material Number Name Date pervious to air but impervious to oil when said 2,334,211 Miller Nov. 16, 1943 materialiswet. 2,392,199 Steiger Jan. 1, 1946 ELMER R. WEAVER. 2,455,975 Buehl et al. Dec. 14, 1948 Certificate of Correction Patent No. 2,516,934 August 1, 1950 ELMER R. WEAVER It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 49, before the Word longer7 strike out no;

and that the said Lettere Patent should be read as corrected above, so that the same may conform t0 the record of the ease n the Patent Office.

Signed and sealed this 7th day of November, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

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