US1949560A - Burner - Google Patents

Description

March 6, 1934. R. D. CHEESMAN 1,949,560

BURNER Filed July 25, 1932 2 Sheets-Sheet l March 6, 1934. R. D. cHEEsMAN BURNER Filed July 25, 1932 2 Sheets-Sheet 2 arcta @ees m75 9%. @klv Mama/m Patented Mar. 6, 1934 UNITED STATES PATENT OFFICE BURNER 'Application July 25, 1932, Serial No. 624,573`

4 Claims.

This invention relates to a method and apparatus for increasing the heating eiciency of burners of the combustion heating type in which an inflammable material, being either a liquid,

I a solid, or a gas, is burned in the presence of a gas, such as oxygen contained in the air, the heat of combustion being transferred by radiation and convection to the body being heated.

Heat transfer from a flame may be by radial tion and convection, the amount of heat transferred by either means varying widely in different applications. An accepted law of radiation is that heat transfer by radiation is proportional to the difference of the fourth powers of the ab- 152 solute temperatures of the bodies emitting and receiving the radiation. Therefore, as the temperatures increase, radiation becomes a more and more important factor in transferring the heat of the flame to the body being heated. It has also IDX been demonstrated that the luminosity of a flame determines to a large extent its radiating power. That is to say, a luminous flame transfers far more heat by radiation than a non-luminous flame at the same temperature, the heat trans- 'z fer from a strictly non-luminous llame being chiefly by convection although all flames carry a certain amount of dustor ash particles, which tend to increase their radiating capacity within narrow limits. It follows therefore that by in- ?3'01 creasing the luminosity of a flame a more efficient 40; jdust This dust may consist of such materials as minerals, ores, or carbonaceous matter, but in any event being of such composition as to be heated to incandescence by the flame and thereby impart luminosity to it. A particular object ofthe invention is to obtain an intimate mixture of ldust with the fuel before burning and preferably this is accomplished by introducing the dust into the same current of air that delivers the fuel 5.5@ into the combustion chamber so that a thorough .5`5 controlled and the best heating effect obtained,

the invention contemplates the regulation of the amount of dust supplied to the flame. y

This method may be advantageously carried out in connection with apparatus for calcining or roasting ores or other mineral products under 00 conditions where intense heat is required, and a further object of the invention is the provision of a burner adapted to utilize the novel method stated above. Such a burner for example finds useful application in the production of 653 cement clinker in the manufacture of Portlandcement. In accordance with one embodiment of the invention, means are provided for withdrawing the dust accompanying the production of the clinker and intimately mixing it with the 70- fuel employed in the burner, so as to impart increased luminosity to the flame and thus intensify its heating effect. However, the dust if desired may be obtained from a source independent of the material undergoing treatment. Means are 7l`4 provided for regulating the amount of dust admitted to the flame to obtain the proper luminosity.

The invention Will-be better understood from the following detail description of apreferred B0, embodiment ofthe invention taken in conjunction with the annexed drawings in which Figure 1 is a plan view of an apparatus including a burner and kiln used in the manufacture of Portland cement; and

Figure 2 is a side elevation of the apparatus of Fig. 1, parts being broken away for greater clearness.

In the production of Portland cement by the apparatus shown in Figs. 1 and 2, the wet or dry mix of raw materials entering into the composition of cement, such for example as limestone and clay, or shale or cement rock, 'is fed into the elevated end of an inclined rotary kiln l and as this kiln slowly revolves the mix is advanced along the bottom of the kiln towards its lower end, constituting a combustion chamber, in which there plays a flame 2 which subjects the mix to intense heat. The calcined or burned material spills off the end of the kiln as clinker which is subsequently ground up to form Portland cement. The granular clinker issuing from the end of the kiln drops down through a vertical passageway 3 formed in a hood 4, closing the lower end ofthe inclined kiln 1, into a clinker pit 5 of oblong shapelocated on a lower floor level. The clinker pit is in communication with the elevated end of an inclined rotary cooling cylinder 6 which serves to carry olf the clinker from the pit 5.

For producing within the interior of the kiln the flame 2 which may extend in some cases to a length of forty feet, there is provided a burner designated generally at A. This burner includes an air-blast pipe 7 mounted at one end in a header 8 and having its other end passed through the wall of the hood 4 adjacent the open lower end of the kiln. Concentrically arranged within the air-blast pipe and held in position by means of spoked spacer rings 9 is a burner pipe 10 which extends substantially the length of the air-blast pipe 7, but which is of somewhat less diameter than the latter so as to afford an air passage between the walls of the outer and inner pipes. A pairof exhaust fans l1 driven by electric motors 12 acts to discharge air into the header 8 and thence out through air-blast pipe 7 and `.burner pipe 10 into the combustion chamber of the kiln. The relative proportion of air passing through each of the pipes 7 and 10 is regulated by manually-operable dampers 13. For introducing fuel into the current of air passing through the burner pipe 10, there is a hopper 14 containing a supply of powdered coal which is fed along a trough 15 by a screw conveyor 16 and discharged into a downspout 17 communicating with the burner pipe 10 at a point relatively remote from the discharge end of the burner ypipe. The

speed of the conveyor may be varied by means,

not shown, to control the flame 2.

According to common practice the air supplied by the exhaust fans 11 to the burner is taken from a locality adjacent the burner or is led in from outside the establishment and while perhaps having entrained therein a small amount of particulate matter, this amount is insufcient to increase the luminosity of the flame to any appreciable degree. The same may be said with Y ,respect to the relatively small amount of ashforming impurities contained in the coal and the inconsequential amount of foreign matter which is usually found intermixed with the coal. While 5in the past air sometimes has been supplied to L the combustion chamber of the kiln to promote combustion of the fuel or has been sucked into the combustion chamber by the draft created by the flame, the dust accompanying the air was not recognized as possessing any utility-although probably it served to increase the luminosity of the flame to a certain extent. But no attempt was made to utilize this dust to increase the heating efficiency of the burner by intimately mixing it with the fuel to impart luminosity to the ame. Nor, so far as I am aware, has it ever co-F ` oblong chamber so as not to be obstructed by the descending stream of clinker is a flue 18 which leads to an air separator 19 of the whirlwind type and this separator is connected in turn, through a conduit 20, with a compartment 20 located on the intake side of the fans 11. The fans thus serve to create a draft through the cooling cylinder 6 and through the pit 5 into the fiue 18 as indicated by the arrows in Fig. 2. The lowerv end of the cooling cylinder, not shown in the figures, is open to afford an unlimited supply of air. The clinker leaving the kiln l is heated to a high temperature and in passing through the rotating cooling cylinder 6 there occurs considerable abrasive and chilling action, resulting in the formation of a certain amount of dust, and consequently this dust will be drawn in with the air entering the flue 18. For regulating the amount of dust entering the burner, the air separator 19 is provided with a manual control 21. Practically any type of air separator which is selectively adjustable to vary its operating efficiency may be utilized in this connection, and as examples of two such types of apparatus reference is made to U. S. Patent No. 1,393,553 of Leonhardt dated October 11, 1921, and U. S. Patent No. 863,189 of Lauritzen dated August 13, 1907.

ln the form of apparatus just described the dust which accompanies the production of clinker may thus be made to serve the useful purpose of increasing the efficiency of the burner, besides incidentally conducing to a more healthful condition in the plant by reducing air contamination. The dust-laden air removed from the cool-l ing cylinder 6 and clinker pit 5, is delivered into header 8 from whence it passes out through the air-blast pipe 7 and the burner pipe 10. The dust carried by the air current passing through the burner pipe will be thus mixed with the particles of powdered coal delivered into this pipe from the downspout 17, and as the dust and fuel is swept along toward the discharge end of the burner pipe the dust will become thoroughly dispersed throughout the combustible mixture and will thereby greatly increase the luminosity of the ame 2. Since this increase in luminosity as above described improves the heating action of the burner a more effective calclnrlg operation will result. The dust borne along by the streamY of air passing through the air-blast pipe 7 which serves to support combustion of the haine will also tend to increase its luminosity, but since the dust of the air-blast pipe does not enter the flame in intimate association with the fuel, its effect will be less pronounced.

While the invention is described and illustrated in connection with an apparatus for burning cement, it is to be understood that this is merely by way of example and that the invention may be utilized in connection with other types of apparatus, in which the efcient transfer of heat from a ame to a surrounding body is a desideratum.

Nor is the invention limited to use with any particular kind of fuel. When for example oil or gas is employed as fuel, the dust particles may be introduced into the ame in a manner similar to that which has already been described in connection with powdered coal.

I claim:

1. An apparatus for producing clinker in the manufacture of Portland-cement comprising in combination an inclined rotary kiln for advancing a stream of cement-forming material therealong, and a burner for producing a flame within the kiln, said burner having a burner pipe of substantial length for discharging fuel under pressure, cooling means for receiving the clinker issuing from the kiln, means for withdrawing-dust laden air from the cooling means and introducing it into the burner pipe at a point relatively remote from the discharge end of the burner pipe, and an air separator selectively regulable to control the amount of dust entering the burner pipe.

2. An apparatus for producing clinker. in the manufacture of Portland-cement comprising in tities of dust from the air entering the burner so combination a rotary kiln arranged to advance a charge of material therethrough, a burner for producing a ame within the kiln, means for discharging dust-laden air into the burner, and an air-separator adjustable to remove variable quantities of dust from the air discharging into the burner so as to regulate the luminosity of the burner ilame.

3. An apparatus for producing clinker in the manufacture of Portland-cement comprising in combination a rotary kiln, a burner for producing a flame within the kiln, a cooler for receiving clinker issuing from the kiln and subjecting it to agitation to produce dust-laden air therein, means for withdrawing the dust-laden air from the cooler and introducing it into the burner, and an air-separator adjustable to remove variable quanas to regulate the luminosity of the burner flame. 4. An apparatus for producing clinker in the manufacture of Portland-cement comprising in combination a rotary kiln arranged to advance a charge of material therethrough, a burner for producing a llame within the kiln, a cooler located adjacent the kiln, means for directing material issuing from the kiln into the cooler, said cooler being arranged to subject said material to agitation to produce a dust-laden air therein, a fan for withdrawing the dust-laden air from the cooler and introducing it into the burner and an air-separator adjustable to remove variable quantities of dust from the air entering the burner so as to regulate the luminosity of the burner llame. RICHARD D. CHEESMAN.

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