US2542194A - Gas generator - Google Patents

Description

Feb. 2-0, 1951 J. A. HANNUM 2,54%194 GAS GENERATOR Filed June 14, 1947 s shee'ts-sheet-z INVENTOR. BY JOHN A. HANNUM ATTORNEYS' ffatenteci 20, 195i GAS GENERATOR John A. Hannum, Detroit, Mich., assignor, by

mesne assignments, to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application June 14, 1947, Serial No. 754,788

This invention relates to a method and appa-` ratus for producing gas under pressure by conned combusticn of a fuel and oxidant and more particularly to the conversion of a small volume of a liquid of relatively high specific gravity into a large volume of permanent or semi-permanent gas of low specific gravity.

Apparatus constructed in accord with this invention performs the same ultimate function as an ordinary gas compressor that employs a rotor, reciprocating piston or the like to receive gas at low pressure, compress it and transmit it at a higher pressure. Such compressors require numerous moving parts that must nt closely with each other to avoid gas leakage and that must be replaced from time to time as they wear during use. Furthermore considerable amounts of power are required to drive the moving parts, particularly when the gas is to be compressed to high pressures and the presence of the moving parts results in noise and vibration.

A general object of the present invention is to provide an improved method and apparatus for producing a compressible fluid, including steam, at high pressure. Another object is to decompose under controlled conditions a liquid with a relatively high speciiic gravity into a relatively large volume of gas under pressure. A further object is to provide a method and apparatus for producfl ing a compressible iiuid under conditions where quietness of operation and freedom from vibration of the apparatus is essential. Still a further object is to supply fuel and oxidant in continuous streams to be burned in a confined combustion chamber to produce elastic iiuids under pressure.

An additional object is to provide apparatus by which fuel and oxidant fed as nongaseous material in the required proportions are mixed and ignited in a continuous reaction to decompose to gases. Still a further object of the invention is to provide an apparatus as indicated that may be conveniently cooled and from which condensate accumulating within the combustion chamber may readily be removed during operation without appreciable loss of pressure in the chamber. Other objects of the invention include the provision of apparatus that is automatically controlled in its operation to feed the required amounts of fuel and oxidant to the nozzle and to afford continuous operation with safety against excess pressures that may be built up as combustion of the fuel and oxidant proceeds.

Further objects of the invention will become apparent from the following specification when read with reference to the accompanying drawings. The novel features of the invention are summarized in the claims.

Referring now to the drawings: Figure 1 is a vertical transverse section through a combustion apparatus embodying the present invention; Figure 2 is a section through Figure 1 as indicated by the lines 2-2 thereon and Figure 3 is a vertical transverse section through a modified form of apparatus embodying the present invention.

The apparatus by Which the present invention is practiced is preferably provided in one of the forms shown in the drawings and in the first case includes as a central component a combustion unit IS in the form of a metal casting. The casting is cored to provide a cooling jacket I2 over substantially its entire surface through which cooling water or the like may be circulated continuously. The Water is admitted through a tting connected at I4 and after it has circulated through the jacket is removed at a similar fitting placed as desired to accomplish most efficient coolant flow over the entire surface of the combustion chamber.

The combustion chamber is indicated :at I5 and is bounded over its entire surface by top and bottom walls Il and I8, end walls I9 and 2) and side walls 2| and 22 of the casting. This chamber includes two, although more or less may be provided, hollow transverse Webs 24 and 25 that act as radiation shields or bailies between the outlet and the major combustion region Within the chamber. Each web is cored as indicated at 26 and the hollow portion thereof opens into the cooling jacket I2 where the transverse webs merge with the side walls 2| and 22 at 3@ as shown in Figure 2. The web 24 is closed at the center of the bottom to provide a drain passage 32 for purposes hereafter described and opens into the jacket I2 through the bottom I8 on each side of the passage 32 in the same manner as indicated at 3D in connection with the side Walls. The web 25 is open at the top as indicated at 311 in. Figure l to communicate with the interior of the jacket I2 through the top wall I'I. It will be evident that coolant circulated through the jacket I2 also cools the Webs 24 and 25 to maintain them at the desired operating temperature.

In order that the webs may properly act as radiation shields or baies they are so arranged that gas traveling from the left-hand side of the combustion chamber (Figure l) must travel a circuitous path over web 24 and under web 25 as indicated by the dotted arrow to reach the outlet. This passes the gases in contact with appreciable cooling surface and effectively prevents heat due to the high temperatures at the point of combustion from traveling across the combustion chamber to the outlet. y y

In order to permit access to the jacket l2 and the Vhollow webs, both for the removal of core sand after the casting is poured and also for maintenance purposes during its life a plate 36 is provided bolted as at 3l to the top and a similar plate 38 is provided bolted at 39 to the side. The unit may be bolted to a suitable foundation by bolts passing through lugs 4U as shown in Figure 2.

The material that is burned within the central portion of the combustion chamber preferably consists of nitromethane as a fuel -afnd tetranitromethane as an oxidizing4 agent supplied tovided by means of the mechanism indicated at 'il which is connected through leads 19 with the leads 65 of the burner 59. Since this control mechanism operates in a well-known manner it will not be described in detail. As stated above the burner 5S includes electric control valves by which the supply of either or both fuel and oxidant may be cut off. If the pressure of the gas passing through the control mechanism 'Il fails below a predetermined value current travels tnrough the leads 'F9 into the burner El] at 65 to open the required valves and supply more of 'either or both fuel and oxidant. On the other hand if theV pressure within the control mechanism ll rises beyond a predetermined point the supply of fuel and oxidant is in like manner decreased. There is thus provided an automatic the point of combustion in stoichiometric pro- 1 portions that burn to end products of 'carbon dioxide, water and free nitrogen. To supply these materials two 'conventional gear pumps te and are provided, the one to pump nitromethane and the other t'o `pump tetranitromethane from separate suitable storage tanks. The pump i5 pumps through piping 1S and a valve i9 to `discharge into a burner 5S as shown in Figure l. and the pump ri pumps through piping '52 and a valve 53 also to `discharge into the burner '5b.

In the burner the two materials are brought together at a suitable mixing nozzle 55 and dis-` provided with a nose 69 that is 4threadedly received in acorresponding opening of the unit it and is secured tightly in place therein. Two sets vof leads indicated at 6G and '85 are provided, the 'formerto'supply'current for the operation of 'the "ignite'r 'and thelatter to operate electric control valves to'control the supply from the pumps and d5 in accord withthe pressure at the outlet of ythe combustion chamber as hereafter described.

The fuel and oxidant that aredischarged from 'the Ynozzle are burned in the enlarged part of 'the combustion'chamber l5 between the end wall ltand the transverse web 24 and the volume of gas generated thereby lls the entire chamber "l5, circulating past the webs and ultimately passing outof the chamber due to the pressure created by the continuous combustion of the fuel and oxidant supplied. The products of combustion leave'thechamber at a threaded opening 'le in which is secured a pipe tting l2. The fitting in turn communicates with a pressure safety `relief valve l, a hand valve 15 and a 'pressureoperated control box 'Hall of conventional construction. After passing through these devices the gas continues through piping 'i8 to its place of use or to a storage tank.

The safety valve "itl functions quickly to relieve the pressure within the combustion chamber if it builds up beyond va safe value. The

hand valve l5 may be closed as desired to cutl off the ilow of gas between the combustion chamber and the piping 18.

Automatic control vof the burning cycle is prothrottlin'g means to control automatically in accord with a predetermined pressure to be maintained at the outlet "i8 that proper amount of fuel and oxidant-necessary at the nozzle 55. A

Due to the cooling action of the jacket i2 and the-fact that water is normally one of the end products of the yreaction taking place in the combustion chamber Va lcertain amount of Icondensate will accumulate therein. This condensate gradually increases to a point where it covers the bottom l of the chamber I5', being free to pass from one side of the web 24 to the other through the opening 32. From time to time this condensate may be removed from the system without substantially Vdecreasing the pressure therein by use of the mechanism now' to be described. A tank with a gauge glass t2 toindicate liquid level is connected through piping te `into a threadedopening communicating with ythe interior of the combustion chamber. A hand valve 3c permits this Aline to be -closedas desired. vln like manner piping 38 leads .from the tank 8F21 vthrough ahand valve VlBEI to piping Si) that discharges intofa dra-in. The tank B and the piping 84 are strong enough to withstand pressures as great as any Yreached within `the combustion chamber I5.

AInoperation the valve 85 -is normally closed and-the valve te is opened when it is desired to drain liquid into the tank te and empty -the com'- bustion chamber. rlhe volume of the tank :is so small -in relation-to the volume of `the chamber l i5 that there is -no appreciable pressure-drop'sin this latter valve `isagain closed. The operation maybe repeated when needed.

"A modified A--form of apparatus embodying the .present "invention is illustratedin'l'igure, that figure being a transverse vertical section through a cylindrical apparatus constructed -of sh-eetor plate material welded together as hereafter'de- 'scribedI and, among other ways, differing fromthe apparatus previously described in that `the fuel and oxidantarenot supplied separatelyas-componente of 'a -bi-fuel but-as a true mono-fuel stored in a reservoirfformed inthe apparatus.

"Referring now to Figure 3 `the Y`apparatus -is ,generallyindicated at lili] and comprises acylindrical'sheet metal and welded tank H32 divided into a fuel reservoir it, a combustion chamber -I B4 and a `cooling jacket m5. rIhe Ycombustion Achamber `is openjat -the'top andinoperationis closed by anremovablecap ortop H0 thatis also v,providedwith a cooling jacket.

.i The reservoir 03gis formed 'Within itheside wall |02 between a bottom plate I2 and a bulk; head ||4 extending across the tank and welded to the side wall. A second bulkhead ||6, spaced above the :rst, provides va region between the reservoir and combustion-chamber for the circulation of coolant so that high temperaturesdeveloped in the combustion chamber do not transmit heat to the fuel in the reservoir. A feed pipe ||8 is anged and Welded to the side |02 as indicated to permit fuel to be added to the reservoir and this feed pipe is normally closed by a removable cap |20. i A

The combustion chamber |04 is formed within a circular shell |22 spaced concentrically within the shell |02 to provide a vertical 4portion |2| of the cooling jacket through which coolant may be circulated. The portion |2| communicates at `|20 and |25 with the region between the bulkheads H4 and ||6 providing for substantially continuous circulation of coolant throughoutthe jacket |05 of the container. The verticalside part |2| of the jacket |05 is sealed at the top by an annular ring shaped plate |28 welded in place and provided with a downturned annular lip |30 and a sealing gasket |3| to provide a. tight seal with the removable top ||0.

The top portion comprises a circular Steel plate |32 to which is secured an upstanding steel ring |34 welded thereto. An outer steel plate |35 is flanged and welded tothe ring |34 as indicated providing within the top a part of the general cooling jacket surrounding the combustion chamber. A hose |38 communicates at |39 with the vertical portion |2| of the ycooling jacket and at |40 with the top part insuring complete circulation of coolant over the entire surface of the combustion chamber. Coolant may be admitted to and removed from the system at convenient points. The top is secured in place on the container by bolts |42 pivotally pinned to flanges |43 of the tank |02.

The mono-fuel, preferably a mixture of nitromethane and tetranitromethane, is transferred from the reservoir |03 to the combustion chamber |04 by a porous ceramic wick |45 resting on the bottom plate ||2 and passing through a ring or sleeve lll secured to each of the bulkheads ||4 and H6. The wick is tightly cemented in the sleeve It? to prevent any leakage between the wick and sleeve side walls from the combustion chamber to the reservoir. Liquid fuel is transferred by the porous wick from the reservoir to its upper surface |50 where it is ignited by an igniter |5| and burned to form gas as previously described in connection with the apparatus of Figures l and 2. As the fuel burns thev pressure in the combustion chamber is increased over that in the reservoir |03 and this pressure is equalized by means of a sleeve |52 that acts as a duct permitting communication between the two parts of the apparatus. The sleeve |52 is tightly packed with screening material |53 that operates as a flame check in accordance with the well-known principle of the Davey safety lamp to prevent flame transfer from the combustion chamber to the reservoir.

Products of combustion formed in the combustion chamber are removed from the apparatus through a sleeve |55 that may be connected to a hose or other container in which the gases are to be received. If desired safety mechanism may be incorporated at this point in the form of a safety blow-off valve that operates automatically in the event the pressure within the combustion chamber becomes excessive. As combustion proceeds the aqueous product of combustion will condense out as liquid on the wall of the jacket |22 due to the cooling effect of the circulating coolant and this condensate will drop down the shell wall and lie in a V- shaped annular trough formed between the shell and an annular ring |58 welded thereto. When the liquid in this trough has accumulated in sufficient quantity it may be removed from the system in' exactly the same manner as described in connection with the tank and the valves and related equipment illustrated in Figure 1 and described above. In order to avoid duplication of description the elements of the apparatus so used are given identical reference characters in Figure 3 as their similar parts that perform the same function have been given in Figure 1.

While both forms of the apparatus described herein employ cooling jackets to remove excess heat from the walls of the combustion chamber under certain conditions this is neither necessary or desirable as for instance in production of hot gases or steam. In such case insulating material of any well-known form, such as glass fiber, is tightly packed around the combustion chamber effectively to insulate its interior from the outer surroundings. Thus in either of the constructions described all of the space occupied by the cooling jacket construction in the side,

end, top and bottom Walls of the combustion chamber is replaced by such an insulating packing or jacket. This may best be illustrated in connection with the construction of Figure 3 Where such a modification would consist in packing the space between the bulkheads ||4 and 6, the vertical portion |2| of the cooling jacket, and the top portion 0 of the top thereof with such insulating material as glass wool. The hose |38 would be dispensed with. There thus would be provided a complete shell of insulating material surrounding the entire combustion chamber.

From the foregoing description it will be evident that by means of the invention gas under pressure may be generated by confined combustion of fuel and oxidant without the necessity of employing numerous moving parts such as are found in the conventional compressor.

It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

I claim:

1. Apparatus for generating gas under pressure comprising an enclosed combustion chamber. a cooling jacket surrounding said chamber t0 cool the walls thereof, a burner nozzle discharging into said chamber, an igniter in said chamber adjacent the point o-f discharge of said nozzle, two conduits leading to said nozzle, one for fuel and the other for oxidant, pumps to transmit said fuel and oxidant respectively through said conduits to said nozzle, electrical control valves in said conduits interposed between said pumps and said nozzle, a first outlet from said chamber including a condensate tank, a second outlet from said chamber including a pressure responsive device, and electrical connections between said pressure-responsive device and said valves to operate said valves in predetermined manner in accord with pressure changes in said second outlet.

2. Apparatus for generating gas under pres- 7 sure comprising an. .enclosed :combustion chain: ber, a cooling jacket surrounding said chamber to cool the walls thereof, a burner nozzle 111s-,

charging into `said chamber, an igniter in `said chamber adjacent the point of discharge of .said nozzle, two conduits leading to said nozzle, ons for .fuel and the' other for oxidant, pumps te transmit said incl and oxidant respectively through said conduits `to said nozzle, electrical control valves in ,said conduits interposed 'between said 'pumps and said nozzle, an outlet ior removing gaseous rp naolucts .of combustion troni said chamber, said outlet including a pressure responsive device, electrical connections between said Ypressure-responsive device and said valves to 0pcra-.te said valves in predetermined manner accord with .pressure changes in said outlet, and an outlet for removing 4condensate `from said chamber, .said outlet comprising a ii-rst conduit including a shut 01T valve, a condensate tank connected to said rst conduit, anda second oon? duit including ,e shut ofi valve, whereby to :permit condensate to be drained from said chamber into said tank and then out of said tank; witnout releasing the pressure therein.

Apparatus for generating gas under pressure comprising ,an enclosed 'combustion oneinber, an enclosed reservoir in ,communication therewith, a erst passage connecting A.seid ,reseryoir andsaid combustion char-aber, ,aiuel :transfer device in said rst passage, asecondpassage onnetting said reservoir and said .combustion charnbar, ,a flame check in 'said second passage, and, traversed by said passages, a jacket suricundiiu-Z said combustion chamber.

4- Apparatus far generating ges runder pre1.- sure comprising .en enclosed combustion cnam: ber, an enclosed reservoir in communication therewith, lfirst passage connecting said reseiwoir and Sad Combustion fahamber, a .ceramic Wick in said first passage, la second `passage connect,- ing said `nasen/,oir and seid combustion chamber.,

a name `.angoli in `said second .-pessage, and, traversed vlby said passages. a Jacket .surrounding said .combustion chamber- .5- Apparatus ier generating gas y.under pressure comprising enclosed kcernbustion ,chainber; cooling Jacket surrounding the sides. and ends of said chamber; c supply system including ltraversi-ng said Jacket for delivering iual and ,oxidant te said chamber; an igniter *ln proximity thereto, said igniter likewise traversing said Jacket; :a Valvcfccntrolied aansluit traversing said jacket for removing gaseous prodnets `ef combustion from said chamber; means communicating t9 said supply system deviations pressure the gaseous sraducts 0f combustion .beine reiner/ed, frein said chambers a val-Vaeontrolled conduit traversing said Jacket in the lagttam Portion ci said chamber.: means for guldcondensate cOllCGting in said chamber for `discberge into said iast-rentioned conduit; and, connected .to said lastfmentioned conduit, a condensate tank disposed outside said jacket below the bottoni of said chanibsr- JOHN a. HANNUM.

REFERENCES oiTED lThe fol-lowing references are of `record in the iile of this Patent:

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