US3614283A

US3614283A - High combustion rate burner

Info

Publication number: US3614283A
Application number: US560555A
Authority: US
Inventors: Allan C Morgan
Original assignee: Cabot Corp
Current assignee: Cabot Corp
Priority date: 1966-06-27
Filing date: 1966-06-27
Publication date: 1971-10-19
Anticipated expiration: 1988-10-19

Abstract

A multiple-fluid fuel burner having a combustion chamber surrounded by a fluid supply channel. An axially extending fluid supply channel member may be used to supply a reactant fluid to the interior of the combustion chamber.

Description

United States Patent 1 3,614,283

[72] Inventor Allan C. Morgan 2,920,691 1/1960 Henwood et a1 431/158 X Winchester, Mass. 3,118,489 1/1964 Anthes 431/158 [21] Appl. No. 560,555 3,273,623 9/1966 Nesbitt 431/352 [22] Filed June 27,1966 98,767 1/1870 Haskins 431/350 X [45] Patented Oct. 19, 1971 1,213,082 1/1917 Dorinckel... 431/176 [73] Assignee Cabot Corporation 1,531,532 3/1925 Wayles... 431/116 Boston, Mass. 1,857,556 5/1932 Lasley 60/3969 X 1,178,573 4/1916 Byers 1 431/216 2,167,856 8/1939 Schonwald 431/174 X [54] HIGH COMBUSTION RATE BURNER FOREIGN PATENTS Z'Claims, 5 Figs- 357,797 9/1922 Germany 60/3974 [52] US. Cl 431/352,

Primary Examiner-Frederick L. Matteson 23/2595 23/277 R Assistant Examiner Harr y B. Ramey [51] lnLCl F2311 15/02 Attorney kenneth W. Brown [50] Field of Search 431/157,

277 R ABSTRACT: A multiple-fluid fuel burner having a combustion chamber surrounded by a fluid supply channel. An ax- Reterences Cited ially extending fluid supply channel member may be used to UN TE STATES PATENTS supply a reactant fluid to the interior of the combustion 2,538,953 1/1951 Yates 431/352 X chamber.

W o'" o 46 42 o o o o Ill 34 i H I HIGH COMBUSTION RATE BURNER The instant invention relates to a novel burner apparatus particularly useful for obtaining very high combustion rates. The invention also relates to a novel process for achieving said high combustion rates.

The burner art has been extensively developed for the purpose of providing efficient combustion of various fuels with oxygen and other oxidant materials. The precise purposes for which burners have been developed have differed, but it has always been most desirable to obtain very high combustion rates and it has been especially desirable to obtain very high combustion rates within some modest spatial limitation so that high combustion rate burners need not take up so much space as to make their construction excessively expensive. Another generally desirable object sought by those who have developed the burner art is the development of a burner combining a high combustion rate with excellent reaction stability. This stability characteristic of a high combustion rate burner is especially important in that it avoids excessive danger of destructive explosions and economically undesirable fluctuation of flame quality.

Still a further problem which has been encountered in the art is the development of high combustion rate burners having good operational characteristics which are capable of stable operation when fed by low-pressure feed systems, for example a system comprising low-pressure air and low-pressure natural gas. It is a matter of common knowledge, of course, that good mixing, commonly thought to be desirable for high combustion rate burners, is much enhanced by high-pressure feed systems which contribute to high-velocity mixing in a combustion chamber or reaction zone. However, high-pressure has systems are relatively expensive and it is generally desirable to minimize pressures at which gases must be handled.

For special purpose uses, it is also desirable to be able to utilize a high combustion rate burrrer in such a way as to largely avoid one of the more serious problems generally associated with a high combustion rate burner, i.e. that of thermal deterioration of materials from which the burner has been fabricated. Thus many in the art have attempted to develop burner configurations which would be useful in effecting the containment of very high temperature flames without excessive thermal deterioration of the burner itself.

Therefore it is an object of the instant invention to provide a burner for efficient use in combustion reactions which produces very high combustion rates, and very high localized temperatures.

Another object of the invention is to provide a burner wherein an especially advantageously situated and relatively cool zone is provided within the confines of the burner.

Another object of the invention is to provide a burner wherein good mixing of reactant gases may be achieved with low-pressure gas feed to the burner.

A further object of the invention is to provide a burner wherein fluid feed thereinto is utilized in regeneratively cooling said burner.

These objects are largely accomplished by the instant invention in providing a perforated and substantially cylindrical burner assembly through which fuel gas and an oxidizing medium may pass radially inward to form a turbulent flame zone.

In order to form a suitably stable flame, it is advantageous that multiple perforations extend along the axial direction of said burner for a distance of at least one-half of the mean diameter of the burner.

In the specification and in the accompanying drawings are shown and described illustrative embodiments of the invention; modifications thereof are indicated, but it is to be understood that these are not intended to be exhaustive or limiting of the invention, but on the contrary they are given for the purposes of illustration in order that others skilled in the art may fully understand the invention, and the manner of applying it in practical applications. The various objects, aspects, and advantages of the present invention will be more fully understood from a consideration of the specification in conjunction with the accompanying drawings.

FIG. I is an elevational view in section of the burner of the instant invention.

FIG. 2 is a schematic flow diagram taken loolcing axially into the burner of FIG. I.

FIG. 3 is a partial section in elevation of a burner of the invention having a feed probe mounted therein.

FIG. 4 is an end view in elevation of the burner of FIG. 3.

FIG. 5 shows a probe especially useful for practice of the instant invention.

Referring to FIG. ll, it is seen that burner 10 comprises an outer shell 12, a tube 14, and a perforated inner tube 116. Both tube 14 and inner tube 16 have machined-out conduits l8 and 20 respectively. Conduits l8 and 20 are joined by passages 22. Wall 23 of inner tube 16 is perforated with numerous radially aimed orifices 24. Gas is supplied to burner 10 through conduit 26. Thus conduit 26, passage 18, passages 22, passage 20 and holes 24 in sequence form a path for introducing gas into combustion zone 25 of burner 10. FIG. 2 shows schematically the flow pattern of gas in the bumer. The area 1100 at the center of the burner is a relatively cool area where the gas streams impinge one on another. Areas I02, shown in FIG. 2, are areas of high turbulence and of the highest flame temperatures.

The burner illustrated in FIG. 11 has a 0.5-inch diameter combustion chamber 25 and the gas orifices 24, 0.022 inch in diameter, are spaced along about 0.75 inch of the linear length of the chamber. There are 28 orifices 24 in the burner illustrated in FIG. ll. Orifices 24 are spaced about 0.25 inch apart along the inner circumference of perforated wall 23.

' FIG. 3 is a radial flow gas mixing burner of the invention comprising a gas supply conduit 30 leading to annular gas distribution channel 32 defined by outer jacket shell 34 and inner burner member 36.

Annular ring slot 38 is cut into burner member 36 and this slot 38 forms a common connection with a plurality of cooling conduits 40, embedded in member 36 and running parallel to the axis of combustion chamber 44. This slot is sealed with faceplate 39. These cooling conduits 40 are embedded in burner member 36. Half of conduits 40 are connected to a coolant inlet line and half are connected to a coolant outlet line, neither of which is shown, but those skilled in the art will readily comprehend their utility and suitable methods of installation.

Alternating with cooling conduits 40 in burner member 36 are rows of small orifices 42, the opening of each directed at the center line or axis of the elongated combustion chamber 44 formed by burner member 36.

As seen most clearly in FIG. 3, a elongated feed probe 46 is positioned to project axially into combustion chamber 44 to provide means for injecting a raw material or some other reactant for the production of pyrogenic products into the burner. Such a raw material would usually be a fluid mass, i.e. gas or liquid, but a solid could also be injected, for example in a fluidizing medium.

The burner illustrated in FIGS. 3 and 4 has 28 orifices 42 of one-sixteenth inch in diameter spaced 0.5 inch apart along the length of the combustion chamber 44 and about 0.8 inch apart around the inner circumference of member 36. Combustion chamber 44 is 2 inches in diameter and about 4 inches in length.

The burner described in FIGS. 3 and 4 has the same advantages as those disclosed generally in this specification, but it is of particular use where very high temperature combustion reactions are to be carried out, for example high-rate reactions between oxygen and natural gas. The auxiliary water cooling made possible by the configuration of the burner of FIGS. 3 and 4 is often more desirable than the regenerative gas cooling of the apparatus described in FIG. 1. One particularly useful modification of the burner shown in FIGS. 3 and 4 would be the cutting of radial orifices shown in FIG. 3 as dotted orifices $3, in feed probe 46 and the use of such oriflees to supply a fluid flowing radially outward into combustion chamber 44. Such a fluid could be, for example, an oxidant like oxygen. A hydrocarbon, for example methane, could be carried into chamber 44 through orifices 42. It has been found that when such a burner is utilized, with separate fluids emitting from orifices in probe 46, and from orifices 42, it is most advantageous to have the orifices 42 and radial orifices in feed probe 46 so arranged in respect to one another that streams of fluid emitting therefrom tend to interleave rather than impinge directly one on the other. Such interleaving usually provides a more desirable mixing action and, in combustion processes, a smoother operation of the burner. 1

Two prime uses of the instant burner are illustrated in the working examples set forth below. One example describes the use of the burner illustrated in FIG. 1 for carrying out a combustion reaction. The other example describes the use of the burner illustrated in FIGS. 3 and 4 for making a carbon black. Of course, neither example should be interpreted as limiting the scope of the invention; both are presented for illustrative purposes only.

EXAMPLE 1 Two standard cubic feet per hour of methane and 30 standard cubic feet per hour of air are premixed and fed at 2 p.s.i.g. into combustion chamber 25 of the burner illustrated in FIG. 1. A flame temperature of 2,600 F. and a heat generation rate of 2,000 BTUs per hour is realized.

EXAMPLE 2 l,l standard cubic feet per hour of oxygen and 550 standard cubic feet per hour of mehane are premixed and passed into the combustion cavity 44 of the burner illustrated in FIGS. 3 and 4. Through probe 46, which is in this case an oil pressure atomization nozzle of the type known to the carbon black art, is introduced 12.5 gallons per hour of an aromatic hydrocarbon feedstock sold under the trade name Aro I-IB. Cooling water is used at the rate of 5 gallons perminute.

The burner is inserted into a cylinder-shaped refractory furnace of 8 inches inside diameter. This furnace is not shown in the drawings because such furnaces are known and would add nothing to the knowledge of those skilled in the art.

In a run of one hour, 30 pounds of carbon black having properties of furnace carbon blacks are collected.

Of course as will be obvious to those skilled in the art on reading the instant application, and as is shown in FIG. 5, probe 46 can be of a larger nuniber of designs. A multiconduit probe 46a comprising not only a first conduit 50 for axially discharging a reactant into the combustion chamber but also a concentric conduit 52 forming a jacket for said first conduit is shown in FIG. 5. The concentric conduit can be used for such purposes as cooling the probe or, when provided with radial orifices 54, for introducing a reactant into the combustion chamber.

A particularly advantageous aspect of the invention is in the introduction of a hydrocarbon gas into the combustion chamber through said orifices 54 in concentric conduit 52 while introducing oxygen inwardly through the walls of the combustion chamber. The hydrocarbon gas and oxygen react to create intensive heat into which an aromatic feed stock or some other make fuel can be introduced axially into the combustion chamber through the aforesaid first conduit 50.

With respect to the operational characteristics of the burner of the invention, several excellent features may be pointed out. For example, the smooth burning characteristics result in a highly stable flame. This stability may be demonstrated in a number of ways, but probably one most impressive characteristic of the burner relevant to its flame stability is the smooth stutter-free sound of the bumers operation.

Moreover, extremely high heat output per unit of combustion area is achieved. Heat rates of the order of million BTUs or more per hour per cubic foot can be obtained with flame temperatures of the order of 3,000 F. and at as ressure feeds of only about 10 p.s.i.g. using the burner o FIE. I.

Heat releases of about 20 million or more BTUs per hour per cubic foot are obtained when the flame temperature is maintained at 2,4000 F. and gas feed is only about 2 p.s.i.g.

The instant burner has very stable bulk recirculation patterns and may or may not have high-intensity microscale turbulence depending on the feed pressures used. The geometry of the burner provides the bulk recirculation patterns while high-intensity turbulence may be achieved by using higher feed pressures and velocities.

Among the numerous variations possible in the construction of the instant burner is the boring of orifices at angles other than normal to the axis of the combustion chamber. Usually such deviations from normal would be made only to overcome shifts in the flame situs which, under certain operating conditions, would tend to shift too far away from the turbulent mixing area. Other variations include offsetting the orifices so that the streams of gases into the combustion chamber interleave rather than collide and dividing the flow of different gases so that they enter by diflerent orifices.

Another outstanding characteristic of the instant burner is achieved by the impingement of the streams of gas feed on one another at the approximate center of the burner tube. A zone of relatively cold gas exists around this center point and this provides an unusually excellent situs into which temperaturemeasuring probes or other specialized apparatus may be inserted without danger of excessive attack from the hotter combustion reaction gases. Moreover, when gases are brought into the burner through channels in the burner walls, a very desirable cooling effect on the burner walls is realized and at appropriate rates of gas flow, an adiabatic operation can be achieved.

Still another important characteristic of the instant burner is the uniformity of the combustion gases emerging from the burner. This characteristic is believed to be achieved because of the highly turbulent mixing within the burner and the subsequent passage of the highly mixed combustion gases into a plug-type flow.

What is claimed is:

l. A bifluid mixing burner for carrying out high combustion rate reactions between a fluid fuel and an oxidant gas which are supplied and released as separate streams into the interior combustion space thereof comprising a cylindrical shell laterally surrounding said combustion space, a plurality of substantially radially directed orifices extending through said shell, said orifices being distributed in a systematic pattern with regard to both the circumferential and longitudinal spacings between same, a concentric lateral housing around the outside of said cylindrical shell and enclosing a uniform, annular channel surrounding the portion of said cylindrical shell containing said orifices, and elongated, hollow probe of much smaller diameter extending axially through the center of that portion of said cylindrical shell containing said orifices, the lateral wall of said probe having substantially radially directed orifices therethrough distributed in a systematic pattern with respect to both the circumferential and longitudinal spacings between same, and means for feeding under positive superatmospheric pressure one of said separate streams to said annular channel and the other of said separate streams to the interior of said hollow probe. I

2. A burner as described in claim I wherein the systematic distribution patterns for the orifices in said cylindrical shell and in the lateral wall of said probe are coordinated so that directly opposed alignment between individual orifices in said shell and individual orifices in said probe is largely avoided.

Claims

1. A bifluid mixing burner for carrying out high combustion rate reactions between a fluid fuel and an oxidant gas which are supplied and released as separate streams into the interior combustion space thereof comprising a cylindrical shell laterally surrounding said combustion space, a plurality of substantially radially directed orifices extEnding through said shell, said orifices being distributed in a systematic pattern with regard to both the circumferential and longitudinal spacings between same, a concentric lateral housing around the outside of said cylindrical shell and enclosing a uniform, annular channel surrounding the portion of said cylindrical shell containing said orifices, and elongated, hollow probe of much smaller diameter extending axially through the center of that portion of said cylindrical shell containing said orifices, the lateral wall of said probe having substantially radially directed orifices therethrough distributed in a systematic pattern with respect to both the circumferential and longitudinal spacings between same, and means for feeding under positive superatmospheric pressure one of said separate streams to said annular channel and the other of said separate streams to the interior of said hollow probe.

2. A burner as described in claim 1 wherein the systematic distribution patterns for the orifices in said cylindrical shell and in the lateral wall of said probe are coordinated so that directly opposed alignment between individual orifices in said shell and individual orifices in said probe is largely avoided.