US3150711A - Gas burner - Google Patents

Description

p 1964 F. L. BROWN ETAL GAS BURNER Filed Dec. 25, 1960 F d Br INVFJVTOR$ I wuumza M William Pazcwb.

United States Patent 3,150,711 GAS BURNER Fred L. Brown and William P. Porcelli, Chicago, 111.,

assignors to Acme Steel Company, Chicago, Ill., a corporation of lllinois Filed Dec. 23, 196i), Ser. No. 77,874 1 Claim. (Cl. 158-116) This invention relates to the art of combustion of mixed gases and particularly to a new construction for a gas burner.

There have been many designs for gas burners of a type which is intended to have the flame front of greatest heat intensity concentrated at an exposed surface of the burner. The gas burners of known designs generally have one principal shortcoming; the flame front at the exposed surface is not uniform so that it presents an uneven intensity of heat across it. One of the ordinary ways of constructing a gas burner of this type is to provide a cup shaped casing having a solid porous refractory material portion exposed to the air on one side and a continuous supply of air and gas mixture introduced at its other side within the confines of the casing so that the air and gas mixture permeates the refractory material Where it can be ignited to burn at the exposed side. It has been learned that, in time, the refractory material cracks because of the heat, and the flame and heat concentration becomes greater at the cracks to thereby provide wide variations in heat intensity across the exposed surface. The apparent reason that the heat and flame concentrates at the cracks is because the gas and air mixture presented to the refractory material flows through the paths of least resistance which are the cracks. The result of this is that the refractory material, if cracked, must be replaced in order to provide uniform heating and, when using a large number of such burners arranged in a row for the purpose of treating material such as continuous lengths of metal strip, the problems of uneven heat and frequent repair make the structure of poor heating characteristics and expensive.

It is, therefore, an important object of the invention to provide an improved surface burner of the type mentioned which overcomes the disadvantages of presently used burners by having a structure which presents a uniformly heated surface to the article being heated and which requires practically no maintenance and repair.

It is another object of the invention to provide an improved surface burner which can be designed to specifically provide localized predetermined regions of different heat concentrations. One of the special advantages of regulation of the heating zones is the ability to provide a deliberate zone of low temperature at the walls of the burner casing so as to prolong the life of the casing and keep it cool enough to touch without being burned.

. In order to provide the improved surface burner of this invention, it is intended that selected size particles of refractory material be used as the medium having the exposed surface where the heat concentration is to exist. This arrangement is in place of the ordinary type solid refractory material. The particles are loosely mixed and not held together by a binder as is customary in other burners. There are times when the burner is desired to be used along an angular path of movement of the material to be heated. If so, it is an object of the invention to compartmentize the burner to minimize the effect of the granular material flowing and producing a sloped pile. By compartmentizing the burner, the main pile of granular particles is broken up into as many piles as compartments and the effect of the slopes of each pile when the entire burner is at an angle is not as severe so that there ice is an approximation approaching the condition where the piles would not be sloped.

It is still another object of the invention to provide an improved burner employing loose refractory particles which burner can be used with its burner surface extending vertically without the possibility of spilling out the loose refractory particles. This is accomplished by providing a screen at the burner surface to hold in the particles.

Other objects and advantages of the invention should be apparent upon reference to the accompanying drawings, in which FIG. 1 shows a partially cutaway perspective view of a preferred embodiment of a surface burner made according to the invention;

FiG. 2 shows a partially cutaway side elevation of the burner of FIG. 1;

FIG. 3 shows an end view of the burner taken along the line 3-3 of FIG. 2;

FIG. 4 shows a side elevation of a modified compartmentized burner of the same type as FIG. 1;

As shown in FIGS. 1, 2 and 3, the burner 1 consists of a casing 2 which is open at its top and provided with four side walls 3, 4, 5 and 6 and a bottom wall 7. Slightly above the bottom wall 7 is positioned a screen 8 which is secured by welding or otherwise at its edges to the walls of the casing 2 so that it is in a spaced parallel relationship with the bottom wall 7. This screen and the bottom wall 7 produce a space 9.

Above the screen 8 is another space 10 which is filled with granular particles 11 and 12. These particles 11 and 12 are preferably of a high temperature refractory material. The particles 11 are of a larger size than the particles l2 and each group of particles is preferably of a substantially uniform size.

In the space 9 is provided a pipe 13 having an inlet 14 at its outer end which can be suitably connected in a conventional manner to a source of a mixture of air and gas under pressure. The inner portion of the pipe 13 is provided with a plurality of small openings 15 for its entire length and around the circumference of the pipe 13 in order to provide exhaust ports for the air and gas mixture within the space 9.

Secured below the bottom wall 7 is a U-shaped pipe 16 having an inlet end 17 and an outlet end 18. This pipe can be connected at its inlet end 16 to a source of water or other coolant which can be circulated through the pipe for purposes of cooling the bottom wall 7 of the casing 2.

There is a definite reason for providing smaller size particles 12 against the walls 3, 4, 5 and 6 of the casing 2. The reason for this is that the air and gas under pressure leaving the ports 15 and filling the space 9 is forced by its pressure up through the refractory particles 11 and 12. The smaller particles 12 have smaller spaces at their interstices and the larger particles 11 have larger space at their interstices so that the gas and air mixtures passing through the refractory material has larger openings' to pass through in the regions of the larger particles 11 than at the smaller particles 12. The result is that a greater gas and air mixture concentration passes between the particles 11 than between the particles 12 and, when the gas and air mixture is ignited at the exposed surface 19 of the particles, more burning occurs in the central location of the larger particles 11 than at the location of the smaller particles 12. The principal advantage of this is that there is a lower temperature adjacent to the walls 3 to 6 of the casing so that the walls remain relatively cool. This permits their being touched with minimum chance of being burned and prolongs the life of the casing.

It has been found that with a burner having casing dimensions of about twelve inches wide by four inches high by eighteen inches long and with the screen 8 positioned about an inch from the bottom wall 7 of the casing Z and with the larger or coarse particles 11 being of about one-third inch to one-sixth inch in diameter and the smaller or fine particles being about one-thirty-second inch to onesixteenth inch in diameter, that good results can be obtained with this type of burner. It is preferable that the particles 11 be of all the same size, but not necessarily essential.

With this arrangement as stated, the result is that an even surface of heat can be obtained at the surface 19 of the burner in the region of the large particles 11 and the temperature is approximately the same throughout the entire surface. Likewise, an even equal temperature is obtained at the surface 19 in the region of the fine particles 12, although it is a lower temperature than that of the surface in the region of the larger particles 11.

In order to keep the flame front at the surface 19, the pressure of the air and gas mixture is suitably adjusted and the desirable condition is visually apparent. However, after prolonged use of a device of this sort, the flame front may have a tendency to withdraw below the surface 19. This has been learned to be a result of the entire unit heating up. In order to overcome this condition, the cooling medium through the pipe 16 has been provided and, by having suflicient flow of cooling fluid through this pipe 16, flame front retraction can be suitably prevented. Again, the flow of coolant is adjusted to an extent to prevent the flame retraction or regression and, this also is apparent visually.

Although the fine particles 12 have been shown as located adjacent to the walls of the burner, it should be understood that they can be concentrated in any region where lower temperature would be required. Thus, any pattern of hotter and cooler heat distribution can be obtained.

It should be evident that the open mesh of the screen 8 provides the means of passage of the air and gas mixture from the space or chamber 9 to the refractory particles 11 and 12. It should also be evident that the size of the mesh should be fine enough that the smaller particles 12 cannot pass through it so that all of the particles are retained in the space 10.

As shown in FIG. 4, a burner of the same type as shown in FIG. 1 can be provided with baffles 20 when it is intended that the burner be used on a slope relative to the horizontal. The purpose of these baffies 20 is to compartmentize the burner to divide it into a plurality of compartments. The advantage of doing this is to break up what would be the slope of a single pile of particles into a plurality of piles of particles having shorter length slopes so that a disproportionate number of particles would not be near the lower end of the burner which might occur when the burner is sloped as the particles 10 flow and tend to seek a horizontal level.

Although only certain embodiments of the invention have been shown and described, it should be clearly understood that the invention can be made in many different ways without departing from the true scope of the invention as defined by the appended claim.

We claim:

A burner comprising, a casing having a first chamber and a second chamber, a separator positioned between said chambers, the first chamber being provided with a bed of loose refractory particles resting on one side of the bed against the separator, the opposite side of the bed being exposed to the atmosphere, means provided for introducing a pressurized gas mixture containing oxygen and a combustible gas into the second chamber, said separator being perforate to allow passage of the gas mixture from the second chamber to the first chamber and through the interstices of the loose refractory particles, said opposite side of the bed exposed to the atmosphere allowing the gas mixture to pass from the first chamber to the atmosphere where it can be ignited, said bed of refractory particles being separated into a first group of uniform size particles and a second group of uniform different size particles wherein the particles of the first group are larger than the particles of the second group, the first group being positioned centrally of the casing in contact with the separator on one side and with the atmosphere on its opposite side, and the second group surrounding and being directly contiguous with the first group as a wall of smaller particles between the first group of larger particles and the side walls of the casing, the interstices between the smaller particles being smaller than those of the larger particles to allow less of the gas mixture to pass between the smaller particles than between the larger particles and thereby maintain the side walls of the casing at a lower temperature than the central region of the bed when the gas mixture is burned because less gas burns adjacent the side walls than at the central region.

References Cited in the file of this patent UNITED STATES PATENTS 1,074,110 Fyfe Sept. 30, 1913 1,223,308 Bone et a1. Apr. 17, 1917 1,256,301 Ellis Feb. 12, 1918 1,677,156 Vaughn June 17, 1928 1,839,515 Wetherbee Ian. 5, 1932 2,311,350 Richardson Feb. 16, 1943 2,703,609 Bain et al Mar. 8, 1955 FOREIGN PATENTS 542,465 Belgium Nov. 14, 1955 792,164 France Oct. 14, 1935

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