US3485590A - Flame chamber and quenching chamber apparatus - Google Patents

Description

Dec. 23, 1969 J, E. LOEFFLER, JR 3,485,590

FLAME CHAMBER AND QUEEICHING CHAMBER APPARATUS s Sheets-$heet 1 Filed July 13, 1967 INVENTOR JOHN E. LOEFFLER, JR.

Fig.1

ATTORNEY FLAME CHAMBER AND QUENGHING CHAMBER APPARATUS Filed July 13, 196'? 3 Sheets-Sheet 2 29 GASES IN 33 23 OUT GASES OUT 16 as 31 2a 32 Fly. 2

INVENTOR JOHN E. LOEFFLER, JR.

ATTORNEY net. 23, 1969 J. E, LQEFFLER, JR A I 3,485,590

FLAME CHAMBER AND QUENCHING CHAMBER APPARATUS Filed July 13, 1967 5 Sheets-Sheet 5 GASES IN FLUID IN IN VENT OR JOHN E. LOEFFLER, JR.

GAS AND f-l'g 3 FLUID OUT BY w M ATTORNEY United. States Patent US. Cl. 23-277 3 Claims ABSTRACT OF THE DISCLOSURE Flame chamber and quenching chamber apparatus are employed for producing gaseous unsaturated hydrocarbons by partial oxidation. The apparatus uses, in a reaction zone, at least one flame unit having an essentially continuous, uniform wave surface. Downstream therefrom, a quench frame is interposed at the reaction zone-quench chamber interface in a structural configuration conforming preponderantly to the flame wave surface. The quench frame is extensively perforate to permit ready passage of reaction products through same. On the downstream surface, the quench frame is enveloped in quenching fluid for uniform fluid-gas contact, between quenching fluid and gas departing the reaction Zone, across whole quenching chamber-reaction zone interface, which contact thus occurs at a distance of preponderantly constant breadth downstream from the flame wave surface.

BACKGROUND OF THE INVENTION Unsaturated hydorcarbons can be produced by the partial oxidation of more saturated hydrocarbons with oxygen in a flame reaction. One of the problems involved in such a reaction is, that, at the temperatures of production for the unsaturated hydrocarbons, products can and do decompose to provide a final mixture having retarded amounts of unsaturated hydrocrabons compared to the maximum amounts initially produced. It is therefore typical to attempt to freeze the reaction shortly beyond the flame to attain an augmented concentration of the desired reaction products. For example, in the preparation of acetylene by the pyrolysis of a premixture of oxygen and methane, a water quench is usually employed shortly downstream from the flame to reduce the temperature of the gaseous products sufficiently to enhance acetylene production.

Recent developments in pyrolysis furnaces, such as have been shown in US. Patent 3,121,616, provide the following sequence of reactor elements: a premixing chamber in which the oxygen and hydrocarbons are premixed; a gas distributor means comprising a bundle of tubular channels conveying gas from the premixer to a reaction zone; a reaction zone wherein gas leaving the distributor is ignited for partial oxidation; and, down stream from the reaction zone, a quench zone for contacting the gases flowing from the reaction zone with a high pressure spray of cooling water.

To maintain a stable flame with such apparatus requires that gaseous reactants be at virtually the same temperature and exhibit essentially the same uniform gas velocity within any given cross section of the gas distributor transverse to the gas flow. As a result, such reactors are seemingly capable of uniform quenching, in a direction transverse to the gas flow, at the beginning of the quenching chamber.

In practice, however, full size commercial production burners form complex, three-dimensional flame patterns which, in combination with simple and eflicient quenching systems provide unequal retention. time of reacting gases within the reaction zone. That is, unequal time between emergence of materials from the flame wave until such materials receive incipient quenching. Thus, for substances passing through the reaction zone, unequal retention time at different zones of the overall flame wave within the chamber results in unequal amounts of products, thereby retarding the efficiency of the reactor, and especially for burners that are used to chiefly produce one particular product, e.g., acetylene.

SUMMARY OF THE INVENTION It is thus an object of this invention to provide reactor apparatus for producing gaseous unsaturated hy drocarbons by partial oxidation wherein augmented quenching uniformity for gaseous products can be achieved. For attaining this object, the reactors disclosed herein exhibit the common concept of performing incipient contact between gaseous products and quenching fluid at a preponderantly uniform distance downstream from the flame wave.

Hence, it is a further object of this invention to provide, within the reaction chamber for each flame unit, a flame having an essentially continuous wave surface essentially free from turbulence-induced. fluctuations and convolutions. In view of the fact'that virtually uniform flame wave surfaces are not generally achieved in practice, the apparatus of this invention includes means which provide a uniform flame wave which usually has merely minor surface undulations. Through special pictorial techniques, flame waves having such minor undulations have been shown, for example, as a portion of the figure presented in the article The Influence of Turbulence on Structure and Propagation of Enclosed Flames, by A. H. Lefebvre and R. Reid, Combustion and Flame, vol. 10, N0. 4, December 1966, pages 361-363.

It is still a further object of this invention quickly and simply to achieve initial contact between gaseous reaction products and quench fluid across the entire quenching chamber-reaction zone interface. Although the invention is particularly directed to apparatus suitable for use in large scale commercial reactors, the invention is also applicable to scaled-down reactors.

These objects are accomplished by providing, in an apparatus for the production of unsaturated hydrocarbons by incomplete oxidation of more saturated hydrocarbons with oxygen in a flame reaction, such apparatus having gas distributor means, a flame chamber, and a gaseous products quenching chamber, the improvement which includes: (l) a gas distributor means containing at least one outlet through which a gaseous stream of premixed oxygen and hydrocarbons flows into the flame chamber for ignition therein and formation of a flame unit having an essentially continuous, uniform wave surface; (2) a perforate quench frame having an upstream surface facing upon the flame chamber and a downstream surface facing upon the quenching chamber, such quench frame bearing in overall appearance a substantially coextensive configurational relationship with the flame wave surface and being spaced apart essentially uniformly downstream therefrom for providing a reaction zone between the flame wave and the quench frame of preponderantly constant breadth in the direction of gas flow from the surface of the flame wave to the upstream surface of the frame, the perforations of the quench frame enabling ready passage of incompletely oxidized gaseous material from the reaction zone into the quenching chamber; and (3) quenching fluid distribution means delivering quenching fluid to the quench frame on the downstream surface thereof for sustaining an envelope of quenching fluid on such downstream surface.

The flame unit of this invention is a stable flame produced by the partial oxidation of unsaturated hydrocarbons and featuring in addition to stability the phenomenon of an essentially continuous, uniform wave surface. Such flame units are meant to include stable flames which can however provide flame waves having merely minor surface undulations, as discussed hereinbefore. A flame unit for purposes of this invention can be a single flame, e.g., one propagated from premixed gases feeding from a single orifice or slot, or an aperture containing a gridwork of vanes or the like within the aperture and thereby producing a single flame from a multiple of orifices. Such flame units can also be formed by the propagation of a flame in the region adjacent the surface of a porous material and thus can be fed by a gaseous premixture issuing through such material. This type of flame unit is made up from a multitude of discrete gas streams formed by gas diffusing through the porous material which, in burning, blend together to prepare the desired, essentially continuous and uniform wave surface.

Such flame units are distinguished from typical prior art stable flames which, although formed from premixed gases issuing from a gas distributor composed of a bundle of tubular channels, nevertheless provide a flame wave surface derived from a multitude of partially blended, partially discrete flames. This results from the spaces remaining between adjacent tubular conduits within the bundle. As a consequence, these partially blended partially discrete flames provide severe peaks and troughs in the overall wave surface; and thus such apparatus as produce this type of wave surface are not contemplated within the scope of the present invention. Typical flame units having the desirable features for the apparatus disclosed herein have been shown in the attached drawings and their formation has been described hereinafter in connection with the description of these drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view, in partial section, of a single flame reactor chamber plus a portion of attendant quenching-chamber apparatus;

FIG. 2 is a vertical sectional View of reactor apparatus yielding a cylindrical flame wave, and showing, in section, a flame chamber having an upright periphery encircled by an enveloping quenching chamber; and

FIG. 3 is a vertical sectional view of reactor apparatus having a quenching frame partially enveloped by the flame chamber.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a visible flame cone 4, having a flame wave 4A and unburned gas cone 3, issues from a gas distributor nozzle 5. Enveloping the flame wave 4A and descending from the gas distributor nozzle 5 is an encircling series of metal rings 6 held rigidly in place by substantially vertical metal ribs 7 fastened to the rings 6 and joined, at their upper ends, to the gas distributor nozzle 5. The encircling metal rings 6 terminate in a coneshaped tip 6A and the vertical ribs 7 are fastened at their lower end to this tip 6A. The metal rings 6 and tip 6A together with the bottom facing of the gas distributor nozzle 5 enclose the reaction zone or flame chamber.

Adjacent metal rings 6 are spaced apart in vertical direction to provide slots 8 for passage of reaction material out of the annular, conically-shaped reaction zone 10 formed between the flame wave 4A and the metal rings 6. Individual rings 6 have depending flanges 11 which extend outwardly away from the flame wave 4A, thus forming an enlarged opening at the lower rim of each metal ring 6. Conduits 12 lead into annular quenching fluid spray heads 9 positioned outwardly from the metal rings 6 and completely around the lower portion of the gas distributor nozzle 5.

In operation, a stream of premixed, or preheated and premixed combustible gases flows from a source not shown and issues from the gas distributornozzle 5 for partial oxidation in the flame chamber, thereby forming the visible flame cone 4 and flame wave 4A. Reaction products within the reaction zone 10 pass through the slots 8 between adjacent metal rings 6. Concurrently, quenching fluid flowing from a source not shown through conduits 12 to the quenching fluid spray heads 9, issues from such spray heads 9 and flows down the exterior surfaces of the metal rings 6, forming a quenching envelope of fluid around the metal rings 6. On individual rings 6, the quenching fluid flows at first downwardly upon the upper portion of the ring and is then deflected slightly outwardly, away from the flame wave 4A by the ring flange 11. Concurrently, these flanges 11 deflect downwardly the reaction products feeding from the reaction Zone 10, thus retarding the direct outward flow of such products and consequently enhancing quenching contact for such products with a cascade of quenching fluid flowing down from the depending flanges 11. Spent quenching fluid and quenched products are then collected by means not shown for subsequent separation.

In FIG. 2 a substantially horizontal upper plate 26 contains an orifice 27. At the perimeter of this orifice 27, on the under surface of the plate 26, there depends a hollow, cylindrical, porous gas diflusion element 16. The orifice 27 and interior hollow region of the diffusion element 16 form a gas distribution chamber 15. At the bottom of the gas diffusion element 16 a disc-shaped plate 28 forms the bottom of the gas distribution chamber 15. A bolt 31 extending from an upper brace 29 down through the gas distribution chamber 15 and through the lower plate 28 is provided with a bottom nut 32 and a top nut 33 for maintaining the bottom plate 28 in snug fit with the gas diffusion element 16 and consequently maintaining this element 16 in snug fit with the top plate 26.

Spaced outwardly from, as well as around, the gas diffusion element 16 and extending slightly through the upper plate 26, are a series of igniters 17. Ignited gas forms an upright cylindrical flame wave 18 spaced apart from, and around, the gas diffusion element 16. A series of cylindrical metal rings 19, spaced outwardly from the flame wave 18, constitute an outer housing for this wave 18. Adjacent metal rings 19 provide horizontal slots 21 for passage of reaction material from an annular-shaped reaction zone formed between the flame wave 18 and the metal rings 19.

Vertical ribs 34 extending downwardly from a cylindrical quenching fluid housing 22 are fastened at their lower end to a flange member extending radially outwardly from the bottom plate 28. The ribs 34 are fastened to the metal rings 19 and maintain these rings 19 in place. The quenching fluid housing 22 encircles the uppermost metal ring around the outer surface thereof and the lower surface of the housing 22 is perforated with a multitude of holes 23 in the area adjacent the uppermost metal ring. Individual metal rings 19 are provided with depending flanges 24 which extend outwardly from the reaction zone 25 and thus form a greater annular opening at the lower rim of each metal ring 19 than the annular opening formed at the upper end of the ring.

In operation of the FIG. 2 apparatus, premixed, or preheated and premixed gases flow from a source not shown through the plate orifice 27 into the gas distributor chamber 15. Initial gaseous material diffusing from this chamber 15 through the gas diffusion element 16 is ignited by the series of igniters 17. Thereafter, subsequent gas diflusing through the element 16 maintains a multitude of small flame cones which blend to form a flame having an upright, preponderantly continuous and uniform flame wave 18 and the igniters 17 are shut off. Reaction products from the annular-shaped reaction zone 25 pass through the slots 21 formed between adjacent metal rings 19 and these products are deflected downwardly by the depending flanges 24 on the rings 19. Quenching fluid feeding from a source not shown flows into the cylindrical quenching fluid housing22 andissues downwardly through the multitude of holes 23 contained in such hous-. ing 22 to form an envelope of quenching fluid around the metal rings 19. Contact is thus obtained between reaction products and quenching fluid at the quench envelope. Spent quenching fluid and quenched products are collected by means not shown for subsequent separation.

In FIG. 3, the upper section of a tube member 39 contains a pilot flame 41 fed by an adjustable pilot gas inlet line 42. Emanating downwardly from the pilot frame 41 is afiame unit having aflame wave 43. Further downstream from the flame wave 43 and within the tube member 39 is a series of metallic rings 44 fastened in place by rib elements 40. The rings 44 are initiated by a cone shaped tip 45 and continue downwardly with each ring 44 having a larger'diameter than its upper, adjacent neighbor. Slots 49 are thus present between adjacent rings 44. The outer surface of the rings 44 formed with the flame wave 43 a hollow, cone-shaped reaction zone 46. At the lower region of the tube member 39 a fluid conduit 47 enters the tube member 39 and rises within the housing formed by the metal rings 44. Located along the conduit 47 are fluid spray heads 48.

For operation of the apparatus shown in FIG. 3, premixed gases entering from a premixing chamber, not shown, into the top of the tube member 39, are ignited by the pilot flame 41. The downward flow of the entering gases establishes the flame wave 43. After the flowing reaction material passes downwardly through the reaction zone 46, it feeds from the reaction zone 46 through the slots 49 between adjacent metal rings 44. Quenching fluid entering the tube member 39 through the fluid conduit 47 issues from the spray heads 48 and cascades along the inner surface of the metal rings 44 thus providing initial contact between quenching fluid and gaseous product along the inner surface of the rings 44. Spent quenching fluid and quenched gaseous products flow from the bottom of the tube member 39 and are then collected by means not shown for subsequent processing.

The metal rings forming the quench frame in FIG. 3 are likewise applicable to the apparatus depicted in FIGS. 1 and 2, in place of the louvered rings. Also, the vertical ribs supporting the metal rings and maintaining their interfacial position between the reaction zone and quench chamber can be simply welded to the rings, or held by other conventional fastening techniques which would be permitted by the cooling obtained from continuous contact with quenching fluid. In addition to slots between metal rings, such quench frame can be an essentially unitary metallic sheet perforated with a multitude of holes. Also, such a unitary metallic sheet could be stamped to punch slots or the like in the metal and thus provide resulting louvers for each slot from the punched out portion of the sheet. Moreover, if such slots are arranged in rows, the metal retained between the rows can form supporting ribs directly in the quench frame metal sheet. Suitable materials of construction for manufacturing such metal quench frames include low carbon and medium carbon steels and also alloy steels such as stainless steels. In addition to metal quench frames, such frame can be suitably prepared from refractory materials. Preferably, for efiiciency and economy, the quenching fluid used in conjunction with such apparatus is water.

In addition to the arrangement of the quenching fluid spray nozzles shown in the drawings, a series of spray heads variously arranged on the quenching chamber side of the quench frame can be employed. For any arrangement, the water spraying on the quench frame should have suflicicnt energy to form an envelope of quenching fluid on the quenching chamber surface of the frame. The retractable igniters shown in FIG. 2 can likewise be employed down from the gas distributor in FIG. 1 for initial ignition of the premixed gases, and thereafter can be withdrawn back into the distributor. The adjustable pilot gas inlet line 42 in FIG. 3, or other suitable flame anchoring devicecan be adjustable along the longitudinal axis of the tube member 39 for positioning the flame wave 43 within the tube member 39. The porous gas diffusion element of FIG. 2 can be composed of ceramic or similar refractory material, which can be prepared, suitably, by cementing together particles of alumina on refractory metals. Such gas permeable materials for use in furnace apparatus for the partial oxidation of hydrocarbons to make acetylene have been shown, for example, in U.S. Patent 2,765,359.

To obtain a gravity assisted envelope of quench fluid,

the apparatus of FIG. 1, for example, is depicted in an upright position with an essentially descending water quench. Although this is the preferred position for operation of such apparatus it is to be understood that the reactor of FIG. 1, for example, could be in essentially horizontal position or the like. Moreover, the quench frame and attendant apparatus of FIGS. 1 and 3, and such apparatus plus the porous gas diffusion element in FIG. 2, can be constructed around lengthy slotsthrough which the premixed gas enters the reaction chamber. This shape of a long and narrow rectangular orifice could replace the tubular aperture now shown and such slots can be arranged in series to form a reactor having rows of independent, slotted openings each with their own attendant quench frame but operating from the same quenching fluid delivery system.

It is to be understood that the shape of the reaction zone in so far as it involves the distance for the gas flow between the flame front and the quench frame will be dependent upon the makeup of the premixed gases entering the flame chamber as well as upon the velocity of these premixed gases entering the reaction zone. Moreover, such breadth of the reaction zone will depend further upon the particular product or products desired. In acetylene production, for example, from a premixed in let gas composed essentially of methane and oxygen, when the velocity and composition of premixed gas is maintained substantially uniform, the distance of gas flow from the flame front to the quench frame will typically remain unchanged for maximum acetylene production.

It is to be understood that, although the invention has been described with specific reference to particular embodiments thereof, it is not to be so limited, since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

I claim:

1. In an apparatus for the production of unsaturated hydrocarbons -by incomplete oxidation of more saturated hydrocarbons with oxygen in a flame reaction, such apparatus having gas distributor means, a flame chamber, and a gaseous products quenching chamber, the. improvement which includes:

(1) a gas distributor means containing at least one outlet through which a gaseous stream of premixed oxygen and hydrocarbons flows into said flame chamber for ignition therein and formation of a flame unit having an essentially continuous, uniform wave surface;

(2) a perforate quench frame having an upstream surface facing upon said flame chamber and a downstream surface facing upon said quenching chamber, said quench frame bearing, overall, substantially coextensive configurational relationship with said flame wave. surface and being spaced apart essentially uniformly downstream therefrom for providing a reaction zone between said flame wave and said quench frame of preponderantly constant breadth in the direction of gas flow from the surface of said flame wave to the upstream surface of said quench frame, the perforations of said quench frame enabling ready passage of incompletely oxidized gaseous material from said reaction zone. into said quenching chamber; and

(3) quenching fluid distribution means delivering quenching fluid to said quench frame on the dOWnstream surface thereof for sustaining an envelope of quenching fluid on said downstream surface; whereby contact'between quenching fluid and incompletely oxidized gaseous material passing from said reaction zone is achieved in said quenching chamber at a prcpo-nderantly uniform distance downstream from the surface of said flame wave and across at least virtually all of the reaction zone-quench chamber interface.

2. The apparatus of claim 1 wherein said quench frame contains orifices having slotted configuration with the longitudinal axis thereof in substantially horizontal posiion, and said quench frame bears projecting flange members flaring outwardly from said frame into said quenchingchamber and inclined downwardly from quenching fluid" inlet means along the upper edge of each orifice, such that quenching fluid delivered to the downstream surface of said frame is deflected over said flange members and cascades downwardly from said flange members across the orifices for contact with incompletely oxidized gaseous material. 3. The apparatus of claim l wherein said gas distributor means comprises at least one substantiallyv cylindrical porous element; Y

. References Cited 7 UNITED STATES PATENTS 2,672,488. 3/1954 Jones p 260-679 3,234,300. 2/1966 Howard s 260-679

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