US2418175A

US2418175A - higginbotham

Info

Publication number: US2418175A
Authority: US
Publication date: 1947-04-01
Anticipated expiration: 1964-04-01

Description

April 1, 1947- B. M. HIGGINBOTHAM IGNITION CATALYST TREATMENT AND APPARATUS Filed Sept. 29, 1943 2 sheets-sheet 1 INVENTOR BEVERLY M. HIGGINBOT HAM ATTORNEY April 1, 1947. 2,418,175

IGNITION CATALYST TREATMENT AND APPARATUS B. M. HIGGINBOTHAM 2 Sheets-Sheet 2 Filed Sept. 29, 1943 INVENTOR r BEVERLY M. HIGGINBOTHAM ATTORNEY Q Patented Apr. 1, 1 947 IGNITION CATALYST TREATMENT AND APPARATUS Beverly M. Higginbotham, Kenmore, N. Y., as-

signor to The Linde Air Products Company, a

corporation of Ohio Application September 29, 1943, Serial No. 504,266

This invention. relates to a method and ap- 4 aratus for igniting combustible gas mixtures and, more particularly, to the ignition of combustible gas mixtures by ignition catalysts.

It has long been known that combustible gas mixtures, such as oxy-hydrogen,' oxy-coal gas, or oxy-ethanol mixtures, can be ignited by bringing them into contact with ignition catalysts, such as platinum, which become incandescent, in

th presence of such gas mixtures. The catalyst is carried on a fixed support, such as a body 16 Claims. (CI. 67-19) elevation, of three different modifications of i8- nitors embodying the principles oi the invention.

oi asbestos, ceramic material, or wire gauze, over which a flowing stream of the combustible gas mixture is passed. Fixed catalysts suffer from.

several disadvantages, along which are the polsoning of the catalyst after a few ignitions in the presence of hydrocarbon gases, and the grad- In accordance with the method of the invention, a flowing combustible gas mixture is ignited by introducing into the mixture in any suitable way such as by blowing a small quantity of discrete finely-divided particles comprising an ignition catalyst, such as platinum in a puff of gas creating agitation in a larger quantity of powder from which only a small portion is used at a time. The catalyst particles are then carried away or .discarded with the products of combustion. It

I V is desirable, although not essential, for the combustible gas mixture to be ignited in a closed ignition zone. Examples of combustible gas mixtures are oxygen-hydrogen, air-ethanol, and oxygen-coal-gas mixtures. all of which may be isual deactivation of the catalyst by the products of combustion gradually accumulating on its surface. Another disadvantage is-the tendency of the catalyst support to sinter in the heat of the flame. Still another disadvantage of fixed catalysts is the relatively longtime interval between the start of gas flow and ignition of the gas, because a fixed catalyst is a relatively large body having a high heat capacity, which retard the spontaneous heating of the catalyst body to the ignition temperature of the combustible gasmixture. I

The principal object of the present invention is the provision of a novel method for igniting combustible gas mixtures overcoming the abovementioned-disadvantages of the prior art. Other objects are the provision of a novel method for igniting a combustible gas mixture by injecting a small quantity of an ignition catalyst powder into the mixture; and the provision of such a, method wherein the ignition catalyst powder is pneumatically injected into the combustible gas mixture.

Further objects are the provision of a novel pneumatic ignitorfor performing the method of the invention; the provision of suchan ignitor wherein the catalyst powderis iniectedinto the combustible gas mixture by one of the gases forming the mixture; the provision of such an ignitor which may be controlled by a remotely located operator;- and the provision 015 such an I" ignitor which is-simple and compact in construction. and positive in its action. a

The above and; other objects,and.the novel features oftheinvention, will'become apparent irom the following description, havingrefe'rence to the annexeddrawings, wherein Figs. 1, 2, and. 3 are all longitudinal sectional views, partly-in nited by ignition catalysts.

By employing onlya few particles of the ignition catalyst powder for each ignition, and discarding these with the products of combustion, the disadvantages of the prior art are overcome. Since no large catalyst body is exposed to the gases, there is no problem of poisoning or deactivation of the catalyst; nor is there a catalyst supportto be sintered by the,heat of combustion. Moreover, the finely-divided catalyst particles have a low heat capacity, thus assuring prompt ignition of a combustible gas mixture because the particles become incandescent so rapidly.

It is economically advantageous for the ignition catalyst to be carried as a thin deposit on discrete finely-divided particles of an inert ma-v terial, such as powdered alumina, calcium carbonate, or carbon. The fineness of the carrier is not critical, but a powder which passes all through a 140 mesh standard Tyler screen has been found suitable. A finely-divided carrier material may be given a deposit of platinum catalyst by first applying to the carrier a platinum salt, such as an aqueous solution of platinum chloride, and then heating the material in air to a temperature of about 700 0., thereby decomposing the platinum salt and depositing platinum metal on the carrier. a

Further details of themethod of the invention will be appar .it from the following description of various tapes of ignitors designed for performing the'method pneumatically. As shown in Fig. 1, one form of ignitor comprises a body ll having a. longitudinal chamber I3 containing a supply It of ignition catalyst powder. A lateral duct l5 above the powder level connects one side of the chamber l3 to a catalyst discharge passage l1 leading along-one side or the body ll. The'discharge passage |1 cuts inwardly below the cham-v ber l3 and then passes centrally through a long thin nozzle |9 projecting from the lower end of the body The passage H has an outlet in the end of the nozzle 19 for discharging catalyst powder into an ignition zone.

A gas, such as oxygen, is supplied to the chamber l3 by a conduit 2| coupled to the body H by an adaptor 23, which opens into the upper end of the chamber. A plug '25, having an orifice of predetermined size designed to give a predetermined body 43 and controlled by a needle valve 63. Passage 49 and the bleeder conduit 55 are both supplied with oxygen by a supply conduit 65 threaded into the body 43 and controlled by a second needle valve 61. Gas flow through the conduit 65 also is controlled by a normally open, quick-acting, lever-operated, shut-off valve 69 between the valve 61 and the body 43.

When operating the ignitor of Fig. 2, the

valves

63 and 61 are opened and. oxygen and fuel gas at superatmospheric pressure are separately delivered from. the passages 49 and 5|, respectively. to a relatively low pressure mixing zone within 'or just outsideof the conical orifice 53. At the same time, oxygen from the conduit 55 bleeds through the-bleeder conduit 55 and builds up a supply of gas under pressure in the closed chamber 45. At the moment when ignition of the combustible gas mixture is desired, the operator depresses the lever of the valve 59, thus suddenly interrupting the flow of oxygen and re- Y leasing the pressure in the chamber 45; The exing and quickly releasing the lever 28, thus suddenly and momentarily injecting oxygen into the chamber l3. This, oxygen carries a small quantity of powderthrough the duct l5 into the passage I1, and thence to the end of the nozzle l9, from which the powder-laden gas is injected into the ignition zone below the nozzle.

The ignitor of Fig. 1 ,also is constructed for forming a combustible gas mixture in the ignition zone below the nozzle I9. A sleeve 29, which fits snugly over the'nozzle l9 and is threaded to the into the ignition zone, where it ignites the com- When the operator rebase of the nozzle, has a central bore 3| aligned with the discharge passage l1 and opening downwardly into a conical' counterbore '33. Two parallel gas passages and 31, on opposite sides of the nozzle l9, have

lower end portions

36 and 38 inclined downwardly and inwardly, toward one another. The

passages

35 and 31 terminate in outlets arranged opposite one another in the wall of the conical counterbore 33 in such a position 'that the oxygen and fuel gas discharged from the respective passages mix together within or just outside of the counterbore 33 to form a combustible gas mixture in the ignition zone below the ignitor. The upper ends of the

gas passages

35 and 31 are provided with oxygen and fuel gas, respectively, by two valve-controlled supply conduits 39 and 4| threaded into the sleeve 29.

Without refilling the chamber 13, fifty successive ignitions of an oxy-hydrogen gas mixture were obtained with the ignitor of Fig. 1, using an ignition .catalyst comprising platinum deposited on a carrier of alumina powder.

plosive force of the compressed gas trapped in the interstices of the powder, as it blows down to the lower pressure in the mixing zone, carries a small quantity of catalyst powder from the chamber into the conduit and through the passage 49 bustible gas mixture. leases the lever of the valve 69 a moment later, the flow of oxygen to the ignitor is resumed and the combustible gas mixture continues to burn below the ignitor. vices couldbeused for controlling the operation of the ignitor. For example, the two

valves

61 and 69 could be replaced-by a singleremotely controlled cam-operated sequence valve having 011., start, and run' positions.

.JWithout refilling the chamber 45 with catalyst powder, seventy-five successive ignitions of an oxy-hydrogen mixture were obtained with the dispenser of Fig: 2, using a catalyst comprising platinum coated on alumina powder.

The ignitor shown in Fig. 3 operates similarly to the ignitor of Fig. 2. However, the ignitor of Fig. 3 is especially designed both for remote control, and to provide easy access to the catalyst powdercontainer when the gas burner portion of the ignitor is inaccessible or fixed in position. Also, the ignitor of Fig. 3 may be operatedin almost any position, whereas the ignitors of Figs. 1 and 2 must be so positioned that the powder in the supply chambers will not cover and clog Fig. 2 shows a preferred modification of the ignitor of the invention, which is somewhat simpler in-constructi'on than the device of Fig. 1. In Fig. 2, a unitary body 43 has a centrally arranged longitudinal powder chamber 45 closed vat its upper end by a removable plug '41. Two

the respective outlet ports I5 and 59. The ignitor of Fig. 3 comprises a gas burner body 1| having two parallel longitudinal passages 13 and 15 for discharging, respectively, oxygen and fuel gas supplied'thereto by conduits 11 and 19,'respectively, connected to suitable sourcesof supply, such as oxygen and

hydrogen cylinders

19 and 99. The passages 13 and 15 both have for parallel passages 49 and 5| on opposite sides of v the chamber 45, for oxygen and fuel gas, respectively,.have inwardly and downwardly inclined outlet portions terminating in oppositely arranged outlets in the wall of a conical bore 53, for separately discharging the respective gases into the ignitionzone ahead of the ignitor to mix therein and form a combustible gas mixture. A

bleeder conduit, 55 extends upwardly from the passage 49 for supplying oxygen to thechamber 45 through a lateral duct 51 registering with a right angular duct 59 in the plug 41. l The passage 5| is supplied with fuel gas, su

as hydrogen, by a conduitbl threaded into the wardlyand inwardly inclined'portions 8| and 93,'

of reduced diameter, terminating in outlets in opposite sides of a conical ,bore 85 for delivering the gases to the mixing zone.

A separate container 81 for catalyst powder has an internal chamber 89 closed atits lower'end by a plug 9|,and a passage 93 for the discharge of gas and powder from the top of the chamber.

A conduit establishes communication between the passage 93 and'the oxygen passage 13 inthe body 1|. The conduit 95 may be brazed or otherwise secured to the body 1|, and is detachably coupled to the container 81 by a hollow-coupling nut 91 carried on the conduit and threaded over It is evident that other de-' .M9,4F1,8,175' f rate of gas flow from the chamber 89 when the ignitor is actuated.

Althougl. the ignitor of Fig.

3 may be operated by a manually controlled valve, as'in Fig. 2, an

arrangement is shown for electrically controlling the operation from a remote "locality. Both of the conduits I1 and Bare controlled by solenoidoperated valves IM and H13, respectively. The

electrical circuits of these valves are contsolled' by a three-way switch I05 which may be so actuated by the operator that both-solenoid valves will be open or closed concurrently, or that either valve may be open and the other closed. With the contact arm I06 of the switch 105 in -the position shown in Fig. 3, when the operator: closes the main line switch I01, the circuits of both valves NH and I03 are cgnnected to the main power circuit I08. Both valves then open and permit the passage of gas to both of the passages 13 and 15. When ignition ofthe gasmixtureis desired, the operator merely rotates the switch contact arm I06 ninety degrees counterclockwise to disconnect the tap H19 from'the electrical circuit, thereby closing the solenoid valve till and interrupting the flow of gas to the passage I3.

As in the modification of Fig. '2, the gas under pressure in the chamber 89 then blows down through the conduit 95 to the lower pressurein the ignition zone ahead of the burner ll, carrying with it a small quantity of the catalyst powder which ignites the combustible gas mixture. A moment later the operatorturns the switch arm Hi3 clockwise back to its original position, the solenoid valve llll again open ..and

the flow of oxygen is resumed to the passage 13.

Theignition catalyst used with the ignitors described above is actually conditiofied by its preparation in' air, and its subsequent storage in an atmosphere of oxygen'within the ignitors, because a film of oxygen is absorbed on the catalyst surface. Theresult is that, on contact with hydrogen or other fuel gas, the catalyst body is promptly heated to incandescence. Storing the catalyst in oxygen is further advantageous as a protection against poisoning of thecatalyst by the poisoning agents usually present in the atmosphere, such as carbon monoxide, hydrocarbons, and water, vapor.

It is to be understood that the term oxygen used'herein is intended to embrace equivalents, such as air. Furthermore, although the catalyst-injectinggas has been described as oxygn in the description of Figs. 2 and 3, it is evident that the fuel gas under some conditions could be used for the same purpose. However, trouble may be expected when using fuel gas as a dispensing medium unless the catalyst was originally prepared in either an inert atmosphere or an atmosphere of the fuel gas. When the catalyst powder has been so prepared, it must not later come into contact withair or oxygen or other gas incompatible with any surface film on the catalyst to prevent premature heating, nor should the catalyst come in contact with any gas that is incompatible with it or may poison it. prior to its passage into the ignition zone, be-

cause of the possibility or explosion and because or the possible deposition of combustion products, suchas water vapor, on the catalyst'surface.

Specific modifications of the method and apparatus of the invention have been described by way of illustration only. It is to be understood, therefore, that the invention iscapable of modiilcation and change in the construction and arrangement of parts, and in the method of operation, within the scope of the invention as defined by the. claims appended hereto. Moreover,

' other ignition catalysts which are the equivalent of platinum may be used for performing the method'without departing from the principles of the invention.

"IclaimL 1-. A method for igniting a flowing combustible mixture of oxygengas nd a fuel gas, comprising separately delivering such gases at superatmospheric pressure into a relatively low pressure mixing zone; buildingup a supply of gas under pressure in a closed chamber containing a supply of powder comprising an ignition catalyst, by bleeding into said chamber a portion of a first one 'ofsuch gases; and injecting a part of the catalyst from said chamber into such mixing zon'eby momentarily interrupting the flow of such first one oi} such gases, thereby causing the gas in said chamber to blow down to the lower pressure in said mixing zone, carrying catalyst powder therewith.'

2. An ignitor having an ignition zone; passages for separately discharging a fuel gas and oxygen into. said ignition zone to mix therein and form a combustible gas mixture; a chamber adapted 'to contain a supply of, powder comprising an ignition catalyst; a gas supply passage opening into said chamber for gas under pressure; a discharge passage for powder-laden gas separate 'from said gas supply passage opening from the upper portion of said chamber for delivering such powder-laden gas into such ignition zone;

and, a quick acting valve controlling said -gas supply passage.

3. An ignitor having an ignition zone; a closed chamber adapted to contain a supply of powder comprising -an ignition catalyst; passages for separately discharging a fuel gas and oxygen into said ignition zone to mix therein and form a combustible gas mixture; a conduit establishing communication between one of said'passages' and said chamber..

4. An ignitor including a closed! chamber adapted to contain a supply of powder comprising an ignition catalyst, an enclosed ignition zone, passages for separately discharging a fuel gas and oxygen into said ignition zone to mix therein and form a combustible .gas mixture, and a conduit establishing communication between one of said passages and the upper part of said chamber; and a valve quickly movable and. located in said one of said passages on the side of the conduit away from said ignition zone to interrupt suddenly on actuation thereof the supply of gas to said one passage and said conduit.

5. An ignitor including means having a closed chamber adapted to contain-a supply of powder comprising an ignition catalyst; an enclosed ignition zone; passages for separately discharging a fuel gas and oxygen into said ignitio'nfzone to mix therein and form a combustible gas mixture; a

duct establishing communication between one of said passages and the top part of said chamber;

an electrically and quicklyoperable valve located in one of said passages between a connection to a source of gas under pressure and said duct and switch means controlling said valve so constructed and arranged as to operate said valve to interrupt suddenly and momentarily the supply of gas to saidchamber and zone.

6. A methodlor igniting a flowing combustible gas mixture comprising'separating a small batch 1 the powdered carrier coated with a metallic igniof discrete finely divided particles comprising an ignition catalyst from a larger body of such particles, injecting said batch into said mixture after its separation from said body, and heating the catalyst particles to the ignition temperature of the combustible mixture by contact with said mixture and while the catalyst particles are moving in and with the combustible mixture and its products of combustion.

7. The method of treating a combustible mixture of a fuel gas and an oxidizing gas which comprises injecting into the mixture finely powdered particles having a thin coating of an ignition catalyst, the surface of which contains a thin film of an absorbed gas of the type of one constituent of said mixture, heating said catalyst to the ignition temperature of the fuel gas by contact of the catalyst with the other constituent of the mixture-from that of its absorbed film tion catalyst has a fineness of about 140 mesh.

13. An igniter comprising passages for fuel gas and oxygen, a combustion zone in which the gases from said passages are confluent, each passage being adapted for connection to a source of gas under pressure, a chamber, finely divided ignition catalyst powder in said chamber, a third passage leading from said chamber above the level of said powder and connecting with one of said as the powdered particles are moved by the moving mixture and carrying said injected catalyst away with the productsof combustion.

8. The process of conditioning an ignition'catalyst powder against poisoning and premature heating which comprises storing the powder in an atmosphere compatible with any gas absorbed by the catalyst surface, extracting a small amount of such powder from the main quantity of the powder in storage, carrying the extracted small amount of powder to its place of catalytic use while surrounded. by an atmosphere compatible with the catalyst for protecting it against being poisoned and becoming heated, injecting the catalyst into a combustible mixture, and igniting the mixture by contact action of said catalyst.

9. The method of preparing and utilizing an ignition catalyst comprising thinly coating finely divided particles of a powdered inert carrier with an ignition catalyst metal, storing the catalyst powder to protect the same against deterioration, agitating and separating at least some of the particles of the stored powder, carrying away a small portion of the powdered catalyst into a stream of combustible mixture, and heating the ignition catalyst to a, temperature for ignition of the mixv ture by contact of the mixture with said catalyst.

10. The process of conditioning an ignition catalyst powder against poisoning and premature heating which comprises storing the powder in an 1 11. method of conditioning an ignition catalystagainst deactivation which comprises foiin'ing whlle in'contact with an oxidizing atmosphere, a thin coating of an ignition catalyst metal on an inert carrier, storing the catalyst coating so iormedin an atmosphere of oxygen, and formaforementioned passages intermediate the ends thereof and means for agitating said powder for carrying a small portion of powder from said chamber through said third passage .toits connecting passage and combustion zone.

14. An ignitor comprising first and second passages for oxygen and fuel gas, a combustion zone in which the gases from said passages are confluent, each passage being adapted for connection to a source of gas under pressure, a, chamber, finely divided ignition catalyst powder in said chamber, a third passage leading from said chamber above the level of said powder and connecting with said first passage intermediate the ends thereof, and means for agitating said powder for carrying a, small portion of powder from said chamber through said third passage to said first passage .and combustion zone, said agitating means comprising a valve controlling said first passage and located between said third passage and said connection to a source of pressure and adapted to be quickly actuated whereby the pressure changes in said first and third passages may create a turbulence in said powder and drive off,

ing and heating intransit and in said chamber.

16. An apparatus for handling an ignition catalyst powder comprising a chamber in which a quantity of the powder may be kept; .means for extracting small amount of powder from said chamber; means for transporting said extracted small amount of powder to its place of use; and

means for protecting the powder against poisoning and heating in transit and in said chamber, said protecting means including a gaseous component of a combustible mixture with which the catalyst powder is compatible.

BEVERLY M. HIGGINBOTHAM.

REFERENCES 'crrE'n The following references are of record in the file of this patent:

UNITED STATES PATENTS Re. 14,167 Sulzenberger July 18,1916