US2225751A - Gas burner - Google Patents

Description

A. G. M KEE Dec. 24, 1940.

eA BURNER Filed 001?. 14, 1958 6 Sheets-Sheet 1.

l l I I I I I I I l I I I INVENTOR Afr/1UP 6' fil /(FE M47 ATTORNEYS IllIlll I I A. G. M KEE Dec. 24, 1940'.

GAS BURNER Filed Oct. 14, 1938 6 Sheets-Sheet 2 INVENTOR. ART/7'07? 5- M KE'E' BY M ATTORNEYS lid? Dec. 24, 1940.. A, G, McKEE 2,225,751

GAS BURNER Filed Oct. 14, 1938 6 Sheets-Sheet 3 1 l UM L M 52 4 24 33 INVENIOR ART/1U}? G-M AEE' ATTORNEYS Dec. 24; 1940. A, MKEE 2,225,751

GAS BURNER Filed Oct. 14, 5!.938 6 Sheets-. Sheet 4 Lz/ Magi 2 38 /9 l l I H 8 /9 figs MENTOR APT/I07? 6. N KEE BY I I m7 1 TTORNEYS Dec. 24, 1940. A. G QM KEE GAS BURNER Filed Oct. 14, 19:58

6 Sheets-Sheet 6 :1? fdjo I IN VENTOR. A zen/w? a. M KE BY M ATTORNEY$ Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to the combustion of gaseous fuel and more particularly to an improved gas burner and valve means for controlling same which is especially adapted for use in connection with heating devices such as blast furnace hot blast stoves, steam generating boilers and the like, particularly when lean fuel gases such as blast furnace gas are burned. In burning large volumes of gas numerous arrangements of air and gas outlet ports and air and gas mixing devices have been proposed and used. Efficient combustion, especially of lean, low heat value gas, such as blast furnace gas, is

H usually obtained by premixing the gas with air l5 and then forcing the mixture into the combustion chamber at a relatively high velocity which is greater than the rate of flame propagation to prevent combustion from traveling back to'the mixing device and destroying it by high temperature.

In the usual type of hot blast stove an opening is provided in the lower part of the combustion chamber through which a removable gas burner is inserted when it is desired to heat the stove.

When the stove is placed onblast the burner is withdrawn and a cover plate must be bolted in place over the opening into the combustion chamber. As air pressures of from 15 to pounds per square inch exist in the stove when on blast; difficulty is sometimes experienced due to leakage or to failure of the bolts which secure the cover plate in position. Cover plates have been blown off from stoves of this type with resulting damage to equipment and danger to the operators. -In my improved gas burner construction, as applied to hot blast stoves particularly, the burner always remains in position in the stove and the necessity of installing and removing a pressure retaining cover plate is eliminated. The pressure in the stove when on blast acts to hold the burner valves in closed position and thus the disadvantages and dangers of the removable type of burner are completely eliminated.

It is among the objects of my invention to provide apparatus for burning gas in which the mixture of air and gas takes place substantially at the point of combustion and with which relatively low air and gas velocities may be used. Other objects of my invention are the provision of a gas burner which will occupy a small space for the volume of gas which can efficiently be burned thereby; the provision of a short flame burner for the combustion of lean gases without damage to the burner from the heat of combustion; the provision of a gas burner which will intimately mix the required quantities of air and gas, regardless of the volumes of air and gas supplied and which may be economically and conveniently constructed substantially entirely of refractory materials so as to withstand the heat of combustion; the provision of a gas burner in which any accumulation of baked on deposits of dust, etc., in the gas passages is discourage and in which any deposits which do form can readily be removed; the provision of a gas burner with which combustion occurs quickly, very close to the burner gas and air outlets and with a very short flame; the provision of a gas burnerand valve control therefor in which an accurate proportioning of the gas and air may be readily and accurately obtained; the provision of a control valve for the gas supply of a hot blast stove or the like in which back pressure, when the stove is on blast,

cannot cause entry of heated air into the gas sup ply pipe with resulting combustion or explosion and gas cannot back into the stove; the provision of a gas burner and control valve arrangement for blast furnace hot blast stoves or the like by which the necessity of withdrawing the air and gas supply pipes and closing the opening in the stove wall therefrom when the stove is put on blast is eliminated and which will supply the necessary large quantities of air and gas required for modern high stove temperature operation; the provision of a hot blast stove burner and valves therefor which are rapidly operable and entirely safe; and the provision of an extremely efficient burner and control valve mechanism for the combustion of gas which is simple in construction and requires a minimum of labor and expense for upkeep and maintenance.

The above and other objects of my invention will appear from the following description of one embodiment thereof, my invention being illustrated in the accompanying drawings as applied to a blast furnace hot blast stove and to a steam boiler furnace, in which-- Figure 1 is a fragmentary side elevation of a hot blast stove which includes my improved gas burner and control therefor.

Figure 2 is a horizontal cross-sectional view taken on line 2-2 of Figure 1.

Figure 3 is -a vertical cross-sectional view through the air and gas flues or passages, taken on line 3-3 of Figure 2.

Figure 4 is an enlarged vertical cross-sectional view through the gas and air distributing housing and control valve mechanism.

Figure 5 is a fragmentary cross-sectional view generally similar to Figure 4 but showing only the structure of the refractory material which defines the air and gas passages and the tubular metallic air and gas diffusing members.

Figure 6 is a horizontal cross-sectional view taken on line I56 of Figure 5.

Figure 6A is an enlarged fragmentary crosssectional view illustrating a supporting bolt arrangement for attaching the refractory blocks to the top cover plate of the valve housing structure.

Figure? is a horizontal CI'OSSr-SECtiOHa]. view taken on. line 1-1 of Figure 5.

Figure 8 is a horizontal cross-sectional view taken on line 8-8 of Figure 5 through a gas port of the burner and also illustrating the wall of the hot blast stove combustion chamber and the supporting and enclosing wall structure for the valve.

housing and burner passages or fiues.

Figure 9 is a view generally similar to Figure 8 but taken on line 99 and representingiagcross section through an air port.

Figure: 10 is a vertical cross-sectional. view of a: modified form of'myinvention applied to a steam boiler and having the flues arranged vertically.

Figure 11 is a-front elevation of a burner assemblyv shown in Figure 10;

Figure- 12 is a vertical cross-sectional View taken substantially on line I2-I2 of Figure 11.

In Figures 1 to. 9 of Ithe=drawings-I have shown my invention as: applied to a typical blast furnace hot blast stove which is rather diagrammatically illustrated at I and which includes the usualcombustion chamber or zone 2. Although the illustrated installationis particularly adapted to replace the original removable gas burner in the'stove I it will be understood that: the advantages of my burner will also besecured on original.- installations.

Referring'p-articularly to Figures 1, 2 and 3, alternately-horizontally arranged air and gas passagesforma substantially rectangular flue structure, generally indicated at P, which extends through the.-wall of the stove I adjacent the bottom of the combustion chamber 2. Externally of. the stove I are the air and gas valves and the distributor'housing which is generally indicated at A. Air is supplied' to this housing througha pipe 3-and:th'e combustible gas through a pipe I; As will be more fully explained later, separate valves are supplied for controlling the supply of -gas and air to the burner. These'air' and gas valvesare mounted upon and operated by valve- stems 5 and 6 respectively, which extend up through the top of the'housing A and are uconnect'edat their upper ends: to cables I which pass over suitable sheaves Band 9 mounted on the frame structure I9. Counter weights I-I assist: in the operation ofthe air and gas valves and: chains I2 .are provided with adjustable hook members adapted to b'e'hooked into 'thebracket I4 when its valve stems are in raised'or open position and be hooked into bracket- I5- when the valve stems a'rein lowered or closed' position.

Referring to Figure 4; the housingA includes metal walls It, a metal bottom plate I1" and a metal top plate I8. These'are suitably'secured together as by riveting or welding and-are lined on their inner surfaces with refractory tile I9. Air and gas pipes and 2|? extend down and connect to the housingA' and are-provided with flanged upper ends 221 and 23 which form supports for valve seats- 24 an'd' 25' respectively. The air inlet-pipe 3- is secured to the top of the valve seat 24* and the vertical cylindrical portion 26 I3 at their lower ends which are of the gas inlet pipe 4 is similarly bolted through the valve seat 25 and the flange 23 of the pipe 2I. It will be seen that a rigid assembly is provided by the housing A, the pipes 29 and El, the valve seats 24 and 25 and the air and gas inlet conduits 3 and 26.

The air supply to the burner is controlled by the air valve 21. As seen in Figure 4 this valve is in its elevated position (with the hook I3 of the chain I2 secured to thelower bracket I4 as shownin Figure 1) and is seated against the valve seat 24 thus shutting off the supply of air which is under suitable pressure in' the pipe 3. The valve stem 5 extends out through the wall of the. pipe 3 through a suitable bushing or packing 28. When the valve is in its lowest position 21', as shown in dot and dash lines in Figure 4, the maximum quantity of air will pass through the pipe 3 and the pipe 28 into the air flues in the'housing A. If the valve 2! be elevated from its position 21 enough to reduce the area of the discharge opening fromthe pipe ZIlinto the air chamber 43 the amount of air supplied will be reduced. until, when the valve is seated against the seat 24, the air supply will be entirely shut off. A separate throttle valve, indicated at 32' (Fig. 4) is. preferably inserted in the air inlet pipe and this valve maybe employed to vary the flow of air into the chamber 43 and the valve 21 maintained either in full open or completely closed position.

The valve stem 6 carries at its lower end a gas valve 29 and, at an upwardly spaced point, a bleedervalve 30. In Figure 4 the valve is shown in its raised position in which the gas valve 29 is seated against the seat 25, thus closing the passagetothe pipe 2I and into the housing A and the gas flues which lead to the combustion chamber. When in this position the bleeder valve 30 is lifted off of its seat 3| on the top of the upwardly extending cylindrical chamber 26. In burner installations. of the type described a gas throttle and shut-off valve of any suitable type, indicated in dot and dash lines at 32, is supplied to shut off or throttle the gas ahead of the burner. In operation, after the valve 32 is closed; thevalve 29 will be elevated into closed position andthe valve 39 will be open providing a free communication to the atmosphere through the opening in the --valve seat 3!. Thus, if any gas should leak past the valve 32 it will escape to atmosphere and cannot enter the combustion chamber. Furthermore, if, due to the back pressure on the valve 29 when the stove is on blast, heated air should escape past the valve seat 25it will not enter the gas supply main but will pass freely to atmosphere through the valve seat 3 I. Bythe provision of the bleeder valve 30 the danger of formation of an explosive mixture in the stove, valve structure or gas main is prevented. The operation is entirely automatic inasmuch as whenever the valve 29 is closed the valve 39 must be open. When the valve 29 is lowered into open position, shown in dot and dash. lines at 29' in Figure 4, the valve 30 will seat -.on its seat3l and. the atmospheric connection be closed. The gas valve 32 may then be opened and gas be supplied to the burner through the'pipe 2|. Adjustment of the flow of gas into the chamber 44 may be eflected either by the valve 29 orthe valve 32, as desired, and as explained'above in regard to valves 21 and 32.

The pipe 2I is mounted on the housing A in the same'manner as the air pipe 29 and it serves as a supportfor the valve seat 25 on which the gas supply pipe 26 is also mounted. A removable clean-out plate 33 closes an opening in the bottom of the housing A'and facilitates removal of accumulated solid material from the housing. To assist in proper seating of the valve 29 when in elevated position a valve grinding lever 34 is pivotally supported on a clamp 35 on the valve stem 6 and, when not in use, may be retained in position along the stem 6 by means of a retaining ring 36. As seen in full lines in Figure 4 the lever 34 is dropped into horizontal position when it is desired to rotate the stem 6 to seat or grind the valve 29 on the seat 25. A swivel connection 31 between the stem 6 and the cable 1 permits this valve grinding movement to take place.

My improved method of burning gaseous fuels contemplates the formation of a plurality of alternate relatively thin layers of gas and air. By this arrangement large volumes of gas and air can be discharged into a combustion chamber at relatively low velocities and with complete and rapid combustion of the gas due to the large gas surface in contact with a correspondingly large surface of air and the intimate mixing and mingling of gas and air which occurs immediately upon the gas and air leaving the ports. Short flame, quiet, even combustion results from this method and the harmful vibration and fluctuation which occurs with long flame combustion is avoided. In order to form the desired plurality of alternate layers of air and gas I provide slot-like gas and air ports which are defined by refractory material and which extend through the wall of the stove l into the housing A. The alternate arrangement of these ports is clearly seen in Figure 3 in which the gas ports are indicated at 38 and the air ports at 39. Spacing blocks 40 of refractory material hold the refractory plates 4i] in the proper spaced relation to form the gas and air ports and the construction of the refractory structure within the housing A is clearly seen from an in spection of Figures 6, 7, 8 and 9.

In Figure 6 is shown a plan view of the refractory structure with the metal cover removed. In order to keep the air and gas separated and to direct the air into the air ports and the gas into the gas ports it is necessary to block off certain parts of the housing. A portion of the top layer of refractory blocks which overlie the air and gas chambers 43 and 44 are preferably supported from the metal cover l8 of the housing A by means of suitable bolts shown at 4! in Figures 5 and 6 and illustrated in detail in Figure 6A.

Figure 7 is an illustrative cross-section showing the bottom layer of refractory material, a hole extending therethrough on the gas chamber side so as to permit cleaning through the removable plate 33.

Figure 8 is an illustrative intermediate crosssection of the valve flue and port structure take-n through one of the gas flues 38. Any section taken through any other gas flue 38 would be substantially the sameand it will be seen that a wall 42 shuts oi? the chamber 43 from the flue 38. The gas, however, which enters the gas chamber 44 through the pipe 2| may pass freely through the slot or flue 38 into the combustion chamber 2 of the stove I. Separating and supporting blocks or bricks 40 are arranged in rows and to further assist in supporting the refractory structure individual, preferably streamlined blocks 45, of the samethickness as the spacing blocks 40, furnish the necessary support while offering a minimum of resistance to the flow of gas through the flat thin slot shaped flues 38. A door 46 provides access to the interior of the gas chamber 44.

Figure 9 is a cross-sectional view through one of the air flues and is typical of all of the air passages. To prevent premature mixture of the air and gas a bafile wall 41 closes off the gas chamber 44 from the air chamber 43. Spacing blocks 40 are arranged in rows and serve to support the transversely extending refractory blocks 40 which form the top and bottom walls of the Stream-lined spacers 45 are also utilized to give the desired support while permitting freepassage of the air from the diffuser pipe 20 into the chamber 43 and through the ports 39.

By blocking off the air passages 39 from the gas chamber 44 and the gas passages 38 from the air chamber 43 by the walls 42 and 41, the gas and air is directed into the proper passages and premature mixture thereof is prevented. There are, of course, as many walls 42 and 41 as there are gas and air ports, each wall extending only from the bottom to the top of a single passage. In Figures 8 and 9 the path of the gas and air is generally indicated by arrows and the discharge thereof in the combustion chamber 2 through the elongated outlet port openings takes the form of a multi-layer sandwich comprising a plurality of relatively thin and long layers of air and gas alternately arranged. The thickness of the layers of air and gas is preferably so proportioned as to provide the proper amount of air in one layer to fully burn the amount of gas which. is discharged through one-half of each adjacent gas port, and this relationship will be maintained as long as the air and gas pressures at the ports are maintained substantially constant.

A large total port area in a small space is pro vided by my arrangement and therefore relatively 10w gas and air velocities may be used with resulting quiet steady flame. As combustion will take place close to the outlets of the ports 38 and 39 a short and efficient flame may be maintained and as the parts of the port structure which are subjected to high temperatures are all made of refractory material no damage thereto will result. My gas and air control valves provide an accurate and easily operable means for opening, and closing and varying the gas and air supply. The valve structure may be made to withstand any back pressure at which the stove may operate when on blast and the necessityof removing burners and attaching a pressure resisting closure plate to the stove wall is completelyeliminated. Danger of explosion due to accidental mixing of hot air and gas is prevented by my safety bleeder valve construction. The blast pressure acts on the under sides of valves 2! and 29 to hold them firmly closed when the stove is on blast and this is an important safety feature of my apparatus.

As gas, and particularly blast furnace gas, always contains a certain amount of non-combustib le solid material which will deposit upon the flues and ports of the burner, I preferably cover, the bottom surface of the flues 38 with loose sand or the like, as indicated inv Figure 8. Any solid material which is deposited may be readily removed by merely removing the sand, and baking of the solids to theflue surface, with resultant decree in cross-sectional area thereof, is prevented.

In Figures 10, 11 and 121 have illustrated an described above. These figures also show my burner as installed in a steam boiler furnace.

The boiler furnace wallsare indicated at. and the. burner is installed to direct the flame into the-combustion chamber Sl. Gas is supplied to the burner through a. gas main 52. and air through the air supply duct 53 which is divided into two branches 54 and 55. Ashut-ofi valve BB-and gas regulating valves. ELare provided! in the gas passages. Thegasmaindischarges intoan' upwardly extending gas; chamber 58, the

,;valves 57 being disposed in the lower part of this chamber.

As is best seen in FigurelO the vertical gas fiues 59-open into the chamber 58. through the bulkhead 60. The gas flues extend to .elongated narrow vertical gas outlet ports El at the furnace end of the burner. The air from the duct 53 is divided by the ducts 54. and 55. and enters the air chambenGZ. This airchamberGZ is divided into sections by a partition plate. 63 (see Fig. 12) and curved walls 64.and65. Thus,

.the air which enters through the duct 55-is di- -tom thereon. The air fines are closed off from the gas chamber 58; by the bulkhead 60. The reinforcing and supporting wall 68 extendshorizontally across the center of the vertical flue structure and may be providedwith vertical holes as fl indicated at 69 to permit mingling of the gasor rber.

air in any one flue59, 66V or 61. With the construction described: the air and gasare not permitted to mix until they are discharged through thevertical ports in the boiler-combustion cham- The previously described advantages of proper proportioning of air and. gas, intimate and immediate mixing thereof into a properly combustible mixture and; efficient short flame combustion are also obtained with my Vertical -flue construction. When the fines are arranged vertically as described there will be only a very small area of horizontal gas flue surface on which solids from the gas can collect and thus the necessity of cleaning the fines maybe largely eliminated. Of course, where the gas burned is sufficiently clean the horizontal arrangement may be used with entire satisfaction.

In the usualblast furnace hot blast stove burner of the type which is removed and replaced by a cover plate when the stove is on blast, the gas and air are discharged into the combustion chamber through a central circular jet and a surrounding annular jet. The gas may be either inside or outside insuch' an arrangement and it will be apparent that, in the sizes commonly employed, the contact surface between the air and gas jets. at theburner is onlyequal to the circumference of the central jet or approximately 7 or 8 feet. With my improved refractory burner, for the same size stove, it is possible to have a length of air and gas contact at the burner outlet equal to feet or more.

This results in a much quicker mixing and burning of the fuel and combustion takes place very close to the sandwiched air and gas outlet ports.

With the. prior structures combustion necessarily takes placev at a distance considerably removed from the burner outlet and is accompanied by surging of the frame and popping back with explosive force which sets up vibrations harmful to the entire equipment. These difiiculties are completely overcome by my. improved burner construction with resultingincrease in life of the stove structure and reduction in upkeep cost.

In hot blast stoves the heating is effected by the combustion of blast; furnace gas which is a lean or low heat value gas. Ordinarily blast furnace gas runs from 90 to 953. t. u. per cubic foot whereas natural gas will run in the neighborhood of 1050 B. t. u. per cubic. foot and artificial gas, as commonly produced by municipal gas plants, will run about 535 B. t. u. percubic foot. Perfect combustion of blast furnace gas with air will not develop a temperature higher than approximately 2200 F. By dividing thev combustion of such gas into a plurality of adjacent long and narrow slots or zones the heat is distributed evenly over the. burner outlet area and by my improvedstructure which permits of the use of refractory material walls defining the slots I have made it possible to burn lean, low heat value gases such as blast furnace gases with an efficient, smooth, quiet, short flame without danger of burning out the burner structure. In the old type of removable hot blast stove burner the air and gasoutlets are made of metal and it is necessary, in order to prevent burning up of the burner nozzles, to employ the long flame combustion where the maximum tem perature was reached at a point considerably removed from the metal nozzle. This long flame resulted in the disadvantages noted above. The old style removable burner couldnot be made of refractory material because the weight of such a structure would render it inoperative. My improved combination, in which the; long and narrow, sandwiched air and gas outlet ports co-act with the refractory walls defining the ports, produces a structure wherein lean, low heat value gases can be consumed most efiiciently and with a relatively stable and quiet short flame without danger of burning out the burner structure.

.In the accompanying drawings I have illustrated my invention as applied to a blast furnace hot blast stove and to the combustion of gaseous fuels in steam boiler plants but is'equally applicable to numerous other installations where an efficient burner for large volume of gas is desired. It will be understood by those skilled in the art that variations and modifications in the structural features of my apparatus and in my method of burning gaseous fuels may be made without departing from the spirit of my invention, and I do not, therefore, wish to be limited to the particular steps and structures described herein, but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In a burner for directing fuel and air intoia combustion chamber, a flue structure having a plurality of adjacent flues which are long and narrow in transverse cross-section, a housing having a gas chamber and an air chamber, alternate ones of said flues opening from said gas chamber and the intermediate flues opening from said air chamber, said fiues having outlet ports disposed in said combustion chamber, and means for controlling the flow of air and gas to said chambers, said means including an air valve, a

gas valve, seats for said valves positioned on the up-stream sides thereof, and means for moving said valves in down-stream direction away from said seats to admit air and gas to said chambers.

2. In a burner for blast furnace hot blast stoves, a flue structure including, a plurality of flues having long and narrow outlet ports, said ports being arranged closely adjacent to each other, walls defining a gas chamber and an air chamber, said flues being arranged to connect alternate ports to said gas chamber and intermediate ports to said air chamber, and means for controlling the flow of air and gas to said chambers, said means including poppet type air and gas valves and seats therefor, said valves and seats being so disposed that back pressure from said combustion chamber when the stove is on blast tends to seat said valves and maintain them in closed position.

3. In combination with a flue structure having a plurality of alternately arranged air and gas flues, a housing having an air chamber connected to said air flues and a gas chamber connected to said gas flues and to an atmospheric bleeder opening, air and gas control valves in said housing, a bleeder valve adapted to control said atmospheric bleeder opening in said housing, and means for interconnecting said gas valve and bleeder valve whereby said bleeder valve will be open when said gas valve is closed and vice versa.

4. In combination with a flue structure having a plurality of alternately arranged air and gas flues, a housing having an air chamber connected to said air flues and a gas chamber connected to said gas flues and to an atmospheric bleeder opening, air and gas control valves in said housing, a bleeder valve adapted to control said atmospheric bleeder opening in said housing, and means for interconnecting said gas valve and bleeder valve whereby said bleeder valve will be open when said gas valve is closed and vice versa, a conduit connected to discharge gas into said gas chamber between said gas valve and said bleeder valve, and independent gas control means for controlling the flow of gas through said conduit.

5. In a burner of the type described, walls defining a plurality of air and gas flues, means for conducting air to said air flues, means for conducting gas to said gas flues, air and gas control valves in said air and gas conducting means respectively, a bleeder valve in said gas conducting means, and means for interconnecting said gas valve and bleeder valve whereby said bleeder valve will be open when said gas valve is closed and vice versa.

6. In a burner of the type described, walls defining a plurality of air and gas flues, means for conducting air to said air flues, means for conducting gas to said gas flues, air and gas control valves in said air and gas conducting means respectively, a bleeder valve in said gas conducting means, means for interconnecting said gas valve and bleeder valve whereby said bleeder valve will be open when said gas valve is closed and vice versa, a conduit connected to discharge gas into said means for conducting gas to said gas flues between said gas valve and said bleeder valve, and independent gas control means for controlling the flow of gas through said conduit.

ARTHUR G. MoKEE.

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