US2725933A

US2725933A - Gas burner apparatus for the generation of carbon monoxide and hydrogen

Info

Publication number: US2725933A
Application number: US224275A
Authority: US
Inventors: Leon P Gaucher
Original assignee: Texaco Inc
Current assignee: Texaco Inc
Priority date: 1951-05-03
Filing date: 1951-05-03
Publication date: 1955-12-06
Anticipated expiration: 1972-12-06

Description

Dec. 6, 1955 P. GAUCHER 2,725,933

GAS BURNER APPARATUS F THE GENERATION OF CARBON MONOX ND HYDROGEN Filed M8. 195] L50 26/; c 5/? BY %iTToRA/EK5 2,725,933 Patented l)ec. 6, 1955 I lice exas Company, New York, N. Y., a corporation of Delaware ApplicationMa'y 3, 1951, Serial No. 224,275 3 Claims. (Cl. 158-99) This invention relates to an apparatus and process for the partial combustion of gasiform hydrocarbons to produce carbon monoxide and hydrogen. The invention is particularly applicable to the partial combustion of a gaseous hydrocarbon with enriched air or substantially pure oxygen'to produce carbon monoxide and hydrogen. 0

In one'of its more specific aspects, this invention relates to apparatus particularly suited for the partial combustron of fuel gas of high heating value, for example, natural gas, with substantially pure oxygen.

Gas mixtures consisting essentially of carbon monoxide 2 and hydrogen are commercially important as a source of hydrogen for hydrogenation reactions, as a source of feed gas for the synthesis of hydrocarbons, oxygenated organic compounds, ammonia, or the like. There is a great deal of interest at the present time in the production of carbon monoxide and hydrogen by the partial combustion of a hydrocarbon with an oxygen-rich gas. Of especial interest is the reaction by which a gaseous hydrocarbon, such as methane or natural gas, is reacted with oxygen-enriched air or substantially pure oxygen.

The partial combustion of a hydrocarbon fuel with oxygen-enrichedair or with relatively pure oxygen to produce carbon monoxide and hydrogen presents unique problems not normally encountered in the burner art. It is necessary to obtain very rapid and complete mixing of the reactants. This reaction also presents problems in protection of the burner, or mixer, from overheating. Because of the reactivity of oxygen with the metal itself from which a suitable burner may be fabricated, it is extremely important to prevent the burner elements from reaching those temperatures at which rapid oxidation of the elements takes place. In this connection, it is import'ant that the reaction between the hydrocarbon and oxygen take place entirely outside the burner proper and to prevent localized concentration of combustible mixarms at or near the surface of the burner elements. The burner elements are subjected to heating by radiation from the reaction, even though the reaction takes place beyond the point of discharge from the burner. Inadequate mixing results in such concentrations of oxygen in localized areas that relatively complete combustion of a portion of the fuel takes place in these areas. This releases large quantities of heat adjacent the burner and overheats the burner elements by radiation. In addition, with any outlet configuration, there are formed eddy current mixtures of the two gases which will burn on the exposed metal surface (flame holders) unless these surfaces are cooled below the ignition temperature of the gas.

Another problem peculiar to this reaction is the tendency for free carbon to form either on the burner or within the reaction space due primarily to inadequate mixing of the gases. The formation of carbon on the surface of the burner often leads to burner failure, since it interferes with the mixing of the gases and causes 10- calized concentrations of oxygen which overheat burner elements or associated refractory.

2 With conventional burners, it has been found: that it 1s necessary to uses quantity of oxygen in excess of: the theoretical to prevent carbon formation. This aggravates the problem of cooling the burner an'd'often causes undesirable high reaction temperatures; Steam is sometimes required to control the reaction temperature and hold it at a reasonable level. The problem is further aggravated by the fact that in the partial combustion: of gases, it is desirable to charge the reactant gases to the burner in a highly preheated state to reducethe oxygen requirements" and give a maximum yield of the desired product gas. V

In the. generation of carbon monoxide and hydrogen from natural gas and relatively pure oxygen for the synthesis of hydrocarbons in commercial quantities, it has been found that conventional burners are unsatisfactory for one or more reasons given above. These burners generally are characterized by failure of burner elements, particularly by burning away of metal at the burner tips even Where these elements have been water cooled.

In the burner art, several'types of burners are known; In View of the foregoing discussion of problems, the type burner in which reactants are premixed and injected from the burner at rates of flow in excess of the rate of flame propagation suggests itself. This'type burner has'not proven satisfactory, however, with relatively pure oxygen and hydrocarbons, for example. The reason that these burners are unsatisfactory is that there is always present a film of gases along the surface of the conduit or. orifice through which they are discharged and this film is movingat a relatively slow rate. The'highly' reactive oxygen-hydrocarbon mixture reacts along this filzmor surface soon causing failure of the burner.

The present invention relates to burners in which the reactants are mixed at the point of discharge from'the burner, and in particular to burners of the annulus type, that is,- burners in which streams of the'reactant gases are introduced through concentric conduits, one of the gases being discharged from a central conduit into admixture with. the other of said gases which is discharged from the annular space between the first conduit and a surrounding conduit. It is importantin this type burner to insure rapid and adequate mixing of the reactant gases after they are discharged from the burner to prevent'localized concentrations of oxygen in the reaction'mixture which would result in hot spots near the burner.

It is also important to prevent the formation of mix tures of reactants adjacent the burner elements, e. g., along the surface of an element. The elements must be adequately cooled, which is another important problem.

In the prior art burners of the type tov which this in vention relates, namely, annulus type burners, provision 5 is sometimes made for cooling the tip of the burner by providing a cooling jacket through which water may be supplied to cool the tip of the larger gas conduit.

An object of this invention is to provide a novel burner or mixer for the partial combustion of fuel gases with gases rich in oxygen, for example, enriched air or relatively pure oxygen, to produce carbon monoxide and hydrogen. Another object of this invention is to provide an annulus type burner which is relatively simple in construction, which insures adequate mixing of the reactant gases, and which is provided in novel manner with protection against overheating and reaction of burner elements with oxygen. A further object of this invention is to provide a burner assembly of the annulus type in which provision is made for cooling the discharge end of both the inner and outer conduit. Still another object is to provide a burnerassembly of the annulus type in which the discharge outlets are maintained in the same relative positions regardless of expansion of the burner elements on heating.

Figure 1 is a sectional view of annulus type burner of this invention. Figure 2 is a sectional view of the burner of Figure 1 taken along line 2-2 of Figure 1.

With reference to the drawings, the burner body comprises an inner member 3, approximately cylindrical in shape, and an outer member 4, also of generally cylindrical shape, is surrounding the inner member and spaced therefrom. The inner member is provided with a passageway 5 extending along its axis for the passage of a stream of one of the gases therethrough. A passage 6 for the second stream of gas is provided by the annular spacing between the inner and outer members. The central passageway 5 terminates in an orifice 8, through which a stream of reactant gas is discharged. A similar orifice 9 is provided at the discharge end of passageway 6. Orifice 9 is symmetrical with orifice 8 and slightly downstream from the point of discharge of orifice 8. One of the reactant gas streams is supplied to the passageway 5 through conduit 11 from a supply line 12. The other reactant gas stream is introduced through conduit 13 into the annular passageway 6 from a supply line 14. Line 12 is disposed within line 14. Line 12 and manifold 14 may supply gases to a number of similar burners, each of which is connected to the

supply conduits

12 and 14 in the manner illustrated.

The inner body member 3 is spaced from the outer member 4 by a plurality of webs 16 which serve to hold the elements rigidly in spaced relationship with one another. Cooling of the discharge ports of the burner is accomplished by circulating cooling liquid through passageways or channels in the burner body. A stream of cooling liquid is introduced to the burner body through pipe 17 into a passageway 18 which extends through the outer body member 4, through web 16; to a passageway 19 in the inner member. Passageway 19 communicates with a cooling channel 21 surrounding orifice 8. Channel 21 extends substantially completely around the orifice 8 and communicates with a passageway 22 through which cooling liquid is discharged into a passageway 23 extending through web 16' to passageway 24 in the outer body member. Passageway 24 conducts the liquid to a cooling channel 26 disposed around orifice 9. The channel 26 extends substantially completely around the orifice 9 and terminates at passageway 27. Passageway 27 connects channel 26 with discharge pipe 28. The cooling liquid discharged through pipe 28 may be supplied to a similar burner, not illustrated, and so on to cool a number of burners in series. The relative order in which the orifices are cooled is unimportant, for example, the cooling liquid may be passed first through a channel disposed about the outer orifice and then through the channel disposed about the inner orifice. It will also be obvious that means might be provided for supplying separate streams of cooling liquid to each of the discharge orifices.

. invention,

An important feature of the burner of this invention is the provision for positively cooling the discharge ports of both the inner and outer conduit to protect the burner from overheating at these critical points. This is accomplished by passing the cooling liquid, suitably water, at relatively high velocity through the channels in the burner body adjacent the discharge orifices or ports. The velocity of the liquid through the cooling channels should be at least feet per second for adequate cooling, and preferably greater than 30 feet per second. The cooling channels are of relatively small cross-sectional area to insure relatively high velocity flow through the channels. This prevents the formation of steam pockets in the cooling channel which would tend to blanket a section of the tip and permit overheating.

Another important feature of the burner of this invention is the suspension of conduit 12 from the inner burner gas at body member 3 by means of conduit 11. The burner body may be supported on conduit 13 which in turn is attached to supply manifold 14. Thus the inner conduit .12 is suspended in floating relationship within conduit 14 permitting relative movement between the various conduits caused by thermal expansion or contraction of the elements by heating or cooling. At the same time body member 3 is positively positioned relative to outer body member 4 so that discharge ports 8 and 9 are maintained in fixed spaced relationship to one another regardless of expansion or contraction of the elements on heating or cooling.

In operation, the burner is installed in the wall or fioor of a suitable furnace. The refractory material forming the wall or floor surrounding the burner is illustrated in the drawing and designated by numeral 29.

in a specific example, a plurality of burners 4 inches in outside diameter are installed in an unpacked reactor. These burners are arranged in a compact cluster and supplied by common gas and oxygen manifolds. The burners are cast of Inconel, an alloy steel containing about 13 per cent chromium, 79.5 per cent nickel and 6.5 per cent iron. The inner feed pipe, corresponding to conduit 11 in the drawings, and the inner header, corresponding to pipe 12 of the drawings, are fabricated of l38 steel, i. e., an alloy steel containing about 18 per cent chromium and 8 per cent nickel. This material has a relatively high coefiicient of expansion. The outer feed pipe and outer header, corresponding to conduits 13 and 14 of the drawing, are fabricated of a chromium alloy steel containing 6 to 8 per cent chromium and having a fairly low coefficient of expansion. Commercially pure oxygen, i. e., oxygen of about 97 mol per cent purity, is fed at 260 F. through the center of the burner, while natural 980 F. is fed through the annulus. Cooling water is passed in series through a number of the burners. The velocity of flow in the cooling channels adjacent the orifices of each burner is calculated as feet per second. The stream of gas discharged from the annulus has a velocity approximately twice that of the center orifice. The gas from the annulus is directed inward toward the stream from the center at an angle of about from the axis of the burner. The gas velocity from the central orifice is about 100 feet per second.

The angle at which the stream from the annulus is discharged into the central stream may vary from about 30 to about from the axis of the central stream. The velocity of the streams may range from about 75 feet per second to about 300 feet per second. Preferably the velocity from the annulus is from 50 per cent to per cent in excess of the velocity from the central orifice.

Obviously, many modifications and variations of the as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A burner structure for mixing a stream of gasiform hydrocarbon and a stream of oxygen-containing gas which comprises a substantially cylindrical inner body member having a central duct terminating in an outlet for the passage of a stream of reactant therethrough, a substantially cylindrical outer body member of larger diameter than said inner body member and disposed about said inner body member to define an annular passageway thercbetween and terminating in an outlet adjacent and surrounding the outlet from said central duct for the passage of a second stream of reactant therethrough, said inner body member having a channel adjacent and spaced about the outlet of said central duct for the passage of cooling liquid therethrough, said outer body member having channel adjacent and spaced about the outlet of said central conduit for the passage of cooling liquid therethrough, a plurality of webs rigidly connecting said inner body member to said outer body member at points spaced from the discharge ends of said body members, said outer body member having a first passageway communicating with said channel thereof, said outer body member having a second passageway extending from said channel thereof and through one of said webs to said inner body member for establishing communication between the channels, said inner body member having a first passageway extending from said second passageway in said outer body member to said channel of said inner body member, said inner body member having a second passageway extending through said one of said webs to said outer body member and communicating with the channel of said inner body member, said outer body member having a passageway extending from said last mentioned second passageway, a first rigid conduit connected to said outer body member in supporting relationship therewith and communicating with said annular passageway, a second rigid conduit rigidly connected to said inner body member and communicating with said central duct, a first feed pipe rigidly connected to said first conduit at substantially a right angle thereto, and a second feed pipe disposed within said first feed pipe and connected to said second conduit, said second conduit supporting said second feed pipe within said first feed pipe in spaced relationship with the walls of said first feed pipe.

2. Apparatus as defined in claim 1 wherein said outer conduit and said outer feed pipe are fabricated of a material having a relatively low co-ei'licient of thermal expansion and said inner conduit and said inner feed pipe are fabricated of a material having a relatively high c0- eflicient of thermal expansion.

3. A burner structure which comprises a substantially cylindrical inner body member having a central duct terminating in an outlet for the passage therethrough of a stream of gas, a substantially cylindrical outer body member of larger diameter than said inner body member and disposed about said inner body member to define an annular duct therebetween terminating in an outlet adjacent and surrounding'the outlet from said central duct, said inner body member having a channel of uniform restricted cross-sectional area substantially completely encircling the outlet of said central duct for the passage of cooling liquid therethrough, said outer body member having a channel of uniform restricted cross-sectional area substantially completely encircling the outlet of said annular duct for the passage of cooling liquid therethrough, a plurality of webs rigidly connecting said inner body member to said outer body member at points spaced from the discharge ends of said body members, the body members having passageways communicating with said channels for supplying cooling liquid to said channels in series, a first rigid conduit connected to said inner body member and communicating with said central duct to supply a stream of gas thereto, a second rigid conduit connected to said outer body member in communication with said annular duct and disposed about said first conduit, a feed pipe connected to said first conduit at substantially a right angle thereto to supply gas to said first conduit and a second feed pipe disposed about said first feed pipe and connected to said second conduit to supply a second gas thereto.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

3. A BURNER STRUCTURE WHICH COMPRISES A SUBSTANTIALLY CYLINDRICAL INNER BODY MEMBER HAVING A CENTRAL DUCT TERMINATING IN AN OUTLET FOR THE PASSAGE THERETHROUGH OF A STREAM OF GAS, A SUBSTANTIALLY CYLINDRICAL OUTER BODY MEMBER OF LARGER DIAMETER THAN SAID INNER BODY MEMBER AND DISPOSED ABOUT SAID INNER BODY MEMBER TO DEFINE AN ANNULAR DUCT THEREBETWEEN TERMINATING IN AN OUTLET ADJACENT AND SURROUNDING THE OUTLET FROM SAID CENTRAL DUCT, SAID INNER BODY MEMBER HAVING A CHANNEL OF UNIFORM RESTRICTED CROSS-SECTIONAL AREA SUBSTANTIALLY COMPLETELY ENCIRCLING THE OUTLET OF SAID CENTRAL DUCT FOR THE PASSAGE OF COOLING LIQUID THERETHROUGH, SAID OUTER BODY MEMBER HAVING A CHANNEL OF UNIFORM RESTRICTED CROSS-SECTIONAL AREA SUBSTANTIALLY COMPLETELY ENCIRCLING THE OUTLET OF SAID ANNULAR DUCT FOR THE PASSAGE OF COOLING LIQUID THERETHROUGH, A PLURALITY OF WEBS RIGIDLY CONNECTING SAID INNER BODY MEMBER TO SAID OUTER BODY MEMBER AT POINTS SPACED FROM THE DISCHARGE ENDS OF SAID BODY MEMBERS, THE BODY MEMBERS HAVING PASSAGEWAYS COMMUNICATING WITH SAID CHANNELS FOR SUPPLYING COOLING LIQUID TO SAID CHANNELS IN SERIES, A FIRST RIGID CONDUIT CONNECTED TO SAID INNER BODY MEMBER AND COMMUNICATING WITH SAID CENTRAL DUCT TO SUPPLY A STREAM OF GAS THERETO , A SECOND RIGID CONDUIT CONNECTED TO SAID OUTER BODY MEMBER IN COMMUNICATION WITH SAID ANNULAR DUCT AND DISPOSED ABOUT SAID FIRST CONDUIT, A FEED PIPE CONNECTED TO SAID FIRST CONDUIT AT SUBSTANTIALLY A RIGHT ANGLE THERETO TO SUPPLY GAS TO SAID FIRST CONDUIT AND A SECOND FEED PIPE DISPOSED ABOUT SAID FIRST FEED PIPE AND CONNECTED TO SAID SECOND CONDUIT TO SUPPLY A SECOND GAS THERETO.