US 2131977 A
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Description (OCR text may contain errors)
Oct. 4, 1938. F, SCHWALBE I 2,131,977
BURNER Filed Oct; 28, 1936 2 Sheets-Sheet l Oct. 4, 1938. F. G. SCHWALBE 2,131,977
BURNER Filed Oct. 28, 1956 2 Sheets-Sheet 2 III/111111117 [11.71/71 Patented Oct. 4, 1938 UNITED STATES BURNER Franz G. Schwalbe, Toledo, Ohio, assignor to Frangeo Company, Toledo, Ohio, a corporation of Ohio Application October 28, 1936, Serial No. 108,043
My invention provides a burner construction particularly adapted for use in connection with furnaces for producing uniform heat distribution from a flaming gas spread in sheet form over a wide area to cover and heat or heat-treat materials or articles. 1 r
The invention provides means for and a method of producing uniform distribution of gas that is subsequently emitted at a constant and uniform quantity rate and in sheet form with a relatively slow movement. By my invention the pressure of the gas is raised, and then the stream flow is alternately and repeatedly expanded and contracted in advance of its ignition and delivery to the furnace. Particularly, the invention provides means for producing a gas and air mixture at a relatively high pressure and uniform distribution through all parts of an extended burner, and then impinging the gas and air mixture to produce reversal of flow to eliminate the velocity pressure head, and repeatedly and alternately expanding and contracting the stream of the gas and air mixture to produce uniform local distribution within the burner and delivery into the furnace by a slow moving stream that is emitted at uniform quantity rate throughout the lengthof an extended narrow opening or a plurality of aligned closely positioned slots.
The invention also provides a burner structure that may be readily varied to produce desired flame characteristics and desired flame lengths and also desired gas and air stratification to render the burner applicable to varied requisites as to heat treatment of articles and materials and as to different dimensional relations existing in furnaces of different forms and/0r used for different purposes. I i
The invention consists in other features and advantages which will appear from the following description and. upon examination of the drawings. Burner structures containing the invention may partake of different forms and may be varied in their details and used to conduct variations of the method and still embody or involve the use of my invention. To illustrate a practical application of the invention, I have selected a burner as an example of the various structures that contain the invention and shall describe the selected structure hereinafter, it being understood that certain features of the invention may be used to advantage without corresponding use of other parts of the invention and without departing from the spirit of the invention as presented in the claims. The particular burner structure selected is shown in the accompanying drawings.
Fig. 1 is a View of a vertical, transverse section of the burner. Fig. 2 illustrates conventionally the furnace and the connections of the burner with a source of supply'of air under pressure and a source of supply of fuel gas. of a horizontal section of the burner. Fig. 4 is a longitudinal, vertical section of a part of the burner structure. Fig, 5 illustrates the details of a fuel pipe connection in the burner structure.
The burner structure I may be used in connection with a glass furnace 2. The burner structure I is located in position to deliver a mixture of fuel gas and primary air and secondary air through a suitable port 3 in a furnace, the products of combustion being withdrawn from the furnace through a port 4 that connects with the stack 6 of the furnace. The fuel gas is directed from a source of supply through a pipe I I to the burner structure and is controlled by a suitable valve I2. The air is conducted from a source of supply of air under pressure through a pipe I3 to the burner structure and is controlled by suitable valves, such as the valve I4 and a damper or slide I6. The pressure of the gas from the source of supply of fuel gas is at the usual low pressure and less than the air pressure that is conveyed to the burner structure through the pipe I3.
The portion of the air controlled by the valve I4 is directed through a nozzle 20 into a passageway through which the gas also moves to the burner structure. The nozzle 20 is located in and extends through a chamber 2I. The fuel gas enters the chamber so as to surround the nozzle. Consequently, the higher pressure of the air operates injector-wise to draw the gas from the pipe I I and produce a pressure in the passageway leading to the burner structure that is greater than that of the gas as delivered by the pipe II. If the pressure of the source of supply of gas is not sufficiently high, it may be raised by any suitable pressure means to a pressure substantially the same as that of the pressure of air and delivered to the burner and the injector nozzle may be omitted. Preferably the flow of the stream from the source of supplyof gas under its raised pressure and the source of supply of air under pressure should be in the same direction in'the conduit leading to the burner. The velocity of stream of air and gas mixture as it leaves the burner and enters the furnace is controlled by varying the volume of the air and gas mixture and the relative gas and air quantities are controlled by control of the primary air quantity.
The nozzle 2G may be formed of a metal tube, one end of which press-fits the interior of the Fig. 3 is a view pipe l9, and the other end is swedged or otherwise reduced in diameter to discharge the air into the gas stream at a relative high velocity rate. The gas enters the leg of the T 22, while the pipe 9 is connected to one of the arms of the T, and the pipe 23 is connected to the other arm of the T and is in axial alignment with the nozzle 29. The nozzle extends through the T, and the air delivery end part is surrounded by the fuel gas.
The pipe 23is connected to a pipe 26 located above a box 21. The ends of the pipe 25 are connected by pipes 28 to the ends of a pipe 29 that conducts the air and gas mixture into a plurality of metal shells 3! located inthebox 21. I
The box 21 may be formed of channel irons 32 and 33 that form the top and bottom and the ends of the box. interior of the box are substantially the same as the corresponding dimensions of the port 3. The port 3 may extend the width of the furnace. The box is-connected to the furnace so asto cover the port.
A plurality of shells 3l 'are located in the box. The shells 31 may be of any desired length. They are'mounted contiguous to each other and extend the length of the port. The cross section of the shells at right anglesto their longitudinal central axis are substantially elliptical, the sides having the smaller curvature being slightly flattened as shown in Fig. 1. The side parts 39 of the shells extend intothe port 3, and are provided with openings ll. The orifice or opening 4| of each shell. is made in the-form of a slot extending the full length of the shell. The exterior and'i'nterior surfaces of each shell flare venturi-wise from the opening 4! toward the central part of the shell. The side part 42 of the shell is closed and sharply curves but with decreasing curvature jalong the top and bottom walls of the shell. The pipe 29extends through the ends of the box- 21 and the shells. The side walls 43 of the shells have openings that exteriorly fit the pipe 29. To fixedly locate the shells on the pipe 29, their ends may be provided with cars 44, and a rod 45 extends through the ends of the box 2! and the cars 4 The pipe 29 has. an exteriorv diameter slightly less than the vertical dimension of the interior of each shell toform restricted passageways or narrow openings of small vertical dimension intermediate the pipe and the inner surfaces of the top and bottom of the shell.
If desired, a single shell may be used extending the length of the port.3 of the furnace. Preferably. a plurality of shells of shorter length are used for convenience of mounting and substitution andto readilyobtain various flame widths. In the form ofconstructionillustrated, the shells have lengths of from 8" to 12". The shells are closely positioned end to end and deliver the gas throughout the length of the port of the furnace in' a substantially continuous sheet.
Thepipe 29 is provided witha plurality of openings-48. The openings are located in the sides of the pipe away'from the openings 3% of the shells and direct the streams of gas mixture that flow with considerable velocity by reason of therelatively high pressure of the gas in the pipe toward the sharply curved end parts 42 of the shells where the flow of the gas is reversed and los'es itsvelocity head pressure. It expands within the shells between the pipe 29 and the closed end 42 of each shell and'at a very much reduced pressure andreduced rate of flow passes through the The height and length of the.
resultant localized'heating at the port.
restricted areas and 52 between the pipe 29 and the end part 39 of the shell Where it again expands. It then passes through the slot or open,- ing 4! and the port 3 into the furnace at a relatively low pressure. Thus, the gas stream is raised in pressure and is then reversed in its direction of flow by impingement and then repeatedly expanded and constricted which insures substantially perfect distribution and uniform emission throughout the length of the orifices or openings Iii into the furnace.
The relative high pressure to which the gas and air'mixture is subjected enables uniform distribution of the gas and air'mixture at substantially a uniform pressure per square inch in the pipe 29; and consequently the gas mixture will pass through the openings 48 into all of the shells at the. same pressure. per square inch. If the gas mixture at. the pressure produced in the pipe 29 were directed toward the openings 4|, the velocity of its emission from the shells would cause immediate local burning of the gas in close proximity to the port opening and prevent progressive flame propagation. By thereduction or elimination of the velocity pressure and the repeated alternate expansion and contraction of the-gas stream within the shells, the gas pressure and the rate of flow of thestream of the gasmixture is reduced to cause the gas mixture to be emitted in the form of a slow moving stream and prevent a turbulent or rapid mixture of ignitedga's with the secondary air in the furnace and the The steady uniform relatively slow movement of the gas enablesp-rogressive combustion of the. fuel gas according. to its rate of movement over the surface of the material and consequently produces a sheet of flame of uniform heat emissivity having a width equal substantially to the length of the port and a length that may be'controlled according to the gas quantity delivered to the furnace.
The stream of the gas and air mixture from the shells is delivered into a stream of secondary air that moves at the same or a slightly less or slightly greater rate according to the results it is desired to accomplish in the furnace. The secondary air is directed from the source of supply of air by the pipe l3, to a drum 6|. 'The quantity that is thus directed to the drum BI is controlled by the slidable damper I6. The drum 6| is connected to a. second drum 62 by means of relatively large pipes 63 that interconnect the two drums ata plurality of spaced points to distribute the stream flow ofthe air over the interior of the drum 62, The movement .of the air through the pipes 63 is controlled by above and below the shells 3! .and through the port 3 into the furnace and above and below the stream of air and gas mixture that flows from the shells 3|. The secondary air quantity taken with the'primary air quantity is. such as to en ablecomplete combustion of the fuel gas in advance of itsentran'ce into the stack 6." The rate of flow of the secondary air maybe regulated and varied by the dampers. The amount of the secondary air that flows above the shells as compared with the amount that flows below the shells may be varied by raising or lowering the shells relative to the central horizontal plane of the box 21. Thus, if desired, the shells may be lowered to increase the quantity of secondary air that is directed above the flame whereby the flame may be blanketed to protect the crown and produce a high rate of transmission of the heat to the material or articles to be heated or heatireated. By regulating the gas quantities and primary and secondary air pressures, the flame may be extended to the outlet of the furnace or may be terminated at any point within the furnace. Its luminosity may be varied, and also its oxidizing or de-oxidizing characteristics may be varied.
The heat of the flame normally heats'the shells 3| and the pipe 29 and causes expansion of the shells relative to the box. To provide for the expansion of the shells 3| relative to the box 2'! a ring II is located on the pipe 29 within an opening 72 formed in each end of the box. A heat-resisting washer, of the type well known in the art, is located on opposite sides of the ring ll. Preferably the ends of the pipe 29 are threaded as at 73, and nuts M are located on the threaded ends of the pipe to clamp the shells, the washers, and the rings together. The pipes 28 that extend laterally from the ends of the pipe 29 will permit the expansion of the shells and movement of the rings ll Within the openings 12 and afford considerable play as between the shells and the box.
1. In a burner structure, a plurality of shells, means for directing fuel gas under pressure against end parts of the inner surfaces of the shells to simultaneously produce reversal of flow and expansion of the gas within the shells, the other end parts of the shells having aligned oblong gas outlets, the shells having restricted gas passageways located intermediate the said end parts of the shells and the said outlets.
2. In a burner structure, a shell having an interior curved surface at one end of the shell, a pipe located in the shell forming restricted passageways above and below the pipe, means for introducing fuel gas under pressure into the pipe, the pipe having an opening for directing a stream of fuel gas against the curved surface to cause impingement of the fuel gas stream and reversal of its flow toward the passageway, the shell having an opening at the other end of the shell for releasement of the fuel gas from the shell.
3. In a burner structure, a shell having an inner cylindrical surface, the inner cylindrical surface having a substantially elliptical form in a plane at right angles to the axes of the cylindrical surface, one end of the shell having a slit, a pipe for introducing fuel gas into the shell, the pipe having an opening for impinging the fuel gas against the part of the inner surface of the shell having the maximum curvature, and causing a reverse flow and expansion of the fuel gas in the shell, the other end of the shell having a slit for liberating the gas from the shell.
4. In a burner structure, a shell having an inner cylindrical surface, the inner cylindrical surface having a substantially elliptical form in a plane at right angles to the axes of the cylindrical surface, one end of the shell having a slit, a pipe having an outer diameter slightly smaller than the smaller'inner diameter of the shell and located centrally with respect to the shell and forming restricted passageways intermediate the proximate surface portions of the pipe and the shell for introducing fuel gas into the shell, the
pipe having an opening for impinging the fuel FRANZ G. SCHWALBE.