US2018956A - Apparatus for firing furnaces with heavy fuel oil - Google Patents

Description

Oct. 29, 1935. w. M, HEPBURN ET AL 2,018,956

APPARATUS FOR EIRING FURNACES WITH HEAVY FUEL OIL Filed April 26, 1953 s Sheets-Sheet 1 i4 32/ I V DVVENTORS WM M HEPB URN ATTORNEY.

E. 6. DE CORIOLIS Oct. 29, -1935. w. M. HEPBURN r AL 2,018,956

APPARATUS FOR FIRING FURNACES WITH HEAVY FUEL OIL Filed April 26, 1953 3 Sheets-Shed 2 INVENTOHS: Mm M HEPB URN BY E. 6.,DEC0R10L13 ATTORNEY.

Oct. 29, 1935. w. M, HEPBURN 2,018,956

APPARATUS FOR FIRING FURNACES WITH HEAVY FUEL OIL Filed April 26, 1953 3 Sheets-$heet 5 I l I l mull W Ar/ NVENToRs: WM. M HEPB URN BY E. G. DECORI LM $4 42524 ATTORNEY.

Patented Get. 29 1935 APPARATUS FoR FIRING FURNAoEs wrrn HEAVY FUEL on.

William M. hepburn and Ernest G. de Coriolis, Toledo, Ohio, assignors to Surface Combustion Corporation, Toledo, Ohio, a corporation of New York Application April 26, 1933, Serial No. 668,018

3 Claims.

In certain types of. industrial furnaces the control of furnace atmosphere is just as importantif not more so than the control of furnace temperature.

Thus unless the furnace atmosphere can be closely controlled the material may be so excessively oxidized or scaled as to be rendered worthless for its intended purpose.

Hitherto the control of atmosphere in furnaces fired with fuel oil has been most difficult of ducing atmosphere, with fuel oil as utilized a deficiency of air results in heretofore an atmosphere containing soot and fine particles of oil in suspension which settle on the material with detrimental results. With fuel oil as ordinarily burned it is also a matter of considerable difficulty to obtain uniform heat distribution in theheating chamber due to localized zones of high temperature where the oil is burning.

The present invention' has for its object to provide apparatus by means of which fuel oil and more particularly heavy fuel oil such as refinery residuum and the like may be utilized for firing furnaces with results comparable to that attainable with the use of fuel gas.

More particularly it is an object of. the invention to provide a firing system which shall embody means for gasifying the oil by partial combustion before it is introduced into the firing chamber of the furnace and for supplying combustion supporting air to the gasified oil in such a way that final combustion occurs in the firing chamber of the furnace.

For a more complete,understanding of the invention, reference is made to the detail description taken in connection with the accompanying drawings forming part of this specification and wherein Fig. 1 is a sectional view of one embodiment of the invention, the view being taken on line ll of Fig. 2;

Fig. 2'is a vertical section on line 2-2 of Fig. 1; Fig. 3 is a horizontal section on line 3-4 of Fig. 1;

. Fig. 4 is a sectional view of one form of oil atomizer that is well adapted for use with the present invention;

Fig. 5 is a view diagrammatically illustrating how the system may be hooked up for temperaturecontrol;

automatic Fig. 6 is a sectional view of another embodiment of the invention, the view being taken on line 6-6 of Fig. 7;

Fig. 7 is a vertical longitudinal section of the furnace shown in Fig. 6, and

Fig. 8 is a detail section taken on line 8-8 of Fig. 7.

Referring first to the form of apparatus shown in Figs. 1 to 3, the furnace to be fired is generally indicated at F and is shown as provided with a 10 roller hearth conveyor C for conveying the material to be heated through the furnace. Only a portion of the furnace is shown, but it will be understood that it is a relatively long affair. The combined gasifying and burner unit is generally 15 indicated at B. For simplicity of illustration the unit is shown as a one piece structure but it will be understood that ordinarily it will be built of firebrick, etc.

One of the essential elements of the firing sys- 20 tem is a combustion chamber or tunnel ll) of substantial size wherein the oil may be partially combusted and otherwise treated. This chamber is indicated at III. In one end wall I l of the cham-- her is an opening I2 through which atomized oil 25 is introduced into the chamber by an oil atomizer of any suitable form and construction.

The oil atomizer is generally indicated at A and is preferably of a type making use of steam and air for atomizing the oil. A well known 30 atomizer of this type is shown in Fig. 4. This atomizer is provided with three concentric chambers a, b and 0 having concentric discharge nozzles. The chamber 0 receives a mixture of steam and atomized oil from a fitting d having an atomizing nozzle at its discharge end. The oil suitably preheated so as to flow readily is delivered to the fitting by a pipe 0 and steam is delivered by a pipe I4. Air issupplied by conduits l5 and-16. The air supplied by conduit l6 flows .into the chamber 0 by way of passages e and also into the annular chamber 12 and the air supplied by conduit l5 fiows into the annular chamber a.

The air'supplied by conduit 15 may be termed complete combustion of the oil is desired in chamber l0.

The discharge end of the atomizer A is shown as surrounded by an annular casing I! secured to the end wall ll of the chamber l and as provided with a ring damper l8. During nor- 'mal operation the damper I 8 will ordinarily be closed. However, before normal operation the chamber ill will be preliminarily heated and such heating is accomplished by burning the oil with its full complement of air, the additional air being admitted through the damper l8.

There is provided near the end wall ll of the chamber a side port 20 which constitutes the discharge end of a duct 22 which leads from the interior of the furnace F. Discharging into the duct 22 is a steam pipe 2| for inducing a flow of waste gases from the furnace. The steam pipe and port 20 are so positioned and arranged that the steam and waste gas will be discharged into the chamber ID in a manner to set up a turbulent condition therein.

Partial combustion of the oil in the chamber I0 produces a combustible gas which flows into the furnace F through conduits or passages-23 which extend laterally from the chamber and which are connected thereto by short vertical passages I9. This combustible gas requires to be supplied with air for supporting combustion thereof in the furnace. This air is supplied by individual nozzles 24 shown as arranged in axial alignment with the passages 23. The nozzles are connected to individual air pipes 25 which, in turn, are connected to a common air supply header 21. It may at times be desirable to dilute the air with steam and to this end the nozzles 24 are also individually connected to steam pipes 26 which in turn are connected to a common steam header 28.

The preferred hookup of the piping system is shown in Fig. '5. Air header 2! is provided with a main valve V1 and the steam header with a main valve V2. The individual air pipes 25 and the individual steam pipes 26 are supplied with individual regulating valves V3 and V4, respectively. 29 indicates the blower for supplying air under pressure to the air header 21. Steam is supplied to the steam header 28 from any suitable, source as from a steam boiler, not shown. The oil supply pipe 0 is provided with a main valve V5. All of these main valves V1, V2 and V are shown as connected to and controlled by a temperature control instrument T. Also connected to the air supply header 2'! are the pipes I 5 and I8 which supply air to the oilatdmizer A. It will be noted that the pipe I6 (which supplies the primary air to the oil atomizer) is connected ahead of the valve V1. The reason for this is that the air supplied by the pipe i6 is just enough to support partial combustion of the oil when the minimum amount of oil is being supplied to the atomizer. The pipe II which supplies steam to the oil atomizer is also connected to the steam header 28 as is the pipe 2| which supplies steam for inducing a fiow of gas through the duct 22.

When the apparatus is operating at maximum capacity, the various main valves V1, V2 and V5 will, of course, be fully opened. When the apparatus is operating at minimum capacity the said valves will permit a minimum flow of the various fluids as will be readily understood. By proper regulation of the individual regulating valves, it becomes a simple matter to regulate the quality of the combustible gas produced in the reaction chamber III. In order that the fuel oil may flow readily to the atomizer A, there is provided any suitable means generally indicated at H for heating the oil. A pump for forcing the oil to the atomizer is indicated at P.

Whereas in Figs. 1 to 3 the oil burner is shown 5 as mounted in the roof of the furnace to fire longitudinally thereof, there may be instances when it is desirable to arrange the burner to fire crosswise of the furnace. A typical showing of such an arrangement is illustrated in Figs. 6 to 7. F2 10 indicates any preferred form of furnace of substantial length and having a hearth C2 intermediate the roof and floor of the furnace. For illustrative purposes, the hearth is shown as comprising rails supported on pedestals 32. The burners are generally indicated at B2 and are shown as positioned one at each side of the furnace inside of the side walls thereof. Those parts in Figs. 6 to 8 which correspond to similar parts in the other figures are indicated by the same base reference characters as of the other figures, but with diacritical marks applied and hence the general construction will be readily understood from what has already been said in connection with the other figures.

The burner B2 differs from the burner already described primarily in that it is provided with upper and lower passages 33 and 23a in order to permit firing above and below the material on the hearth. The method of producing combustible gas in the reaction chamber Illa of the burner B2 is exactly the same as that already described.

In addition to serving as a means for converting fuel oil into a combustible gas, the improved burn- 3 er possesses the great practical advantage of being readily adapted for burning ordinary fuel gas such as natural gas, for example. Thus, in case it is preferred to burn ordinary fuel gas rather I than to generate a special gas from oil, the nozzles 24 which discharge into the passages 23 may be 1 utilized for mixing air and gas individually supplied thereto. In such case the pipes 26 which ordinarily serve as steam pipes would be utilized for supplying gas to the nozzle 24 and the piping system otherwise modified as will be readily understood. The type of burner shown in Figs. 6 to 7 lends itself to an unusual degree for use as a gas burner since the various passages 33 and 23a extend in series longitudinally of the furnace as 60 is customary in heat treating furnaces which are fired with ordinary fuel gas.

It will be noted that the passages 23 through which the products of reaction flow from the reaction chamber are relatively remote from the end wall I I of the chamber I. That portion of the chamber between the end wall II and the first passage 23 can be considered as the primary reaction zone and the balance of the chamber asa secondary reaction zone or a collecting zone for the products of reaction produced in the first portion of the chamber. Any tendency for the products of reaction to crowd into that end of the chamber remote from end wall II is readily compensated for by adjustment of the air supply to the various air nozzles 24, as will be readily understood.

Since the oil is gasifled in a chamber which is in effect part of the furnace structure, there is practically no loss of heatin the gasification of lo the oil since the resulting gases flow while in a flaming condition directly into the furnace. The burner unit as a whole is a relatively simple affair and hence involves no great construction expense. One important advantage of a burner unit fonning the subject of this invention is that the oil atomizer is of such capacity as to have relatively large flow ports and hence troubles due to clogging of the ports due to foreign material in the fluids supplied to the atomizer are reduced to a minimum.

What we claim is:

1. A furnace comprising, 'in combination a heating chamber, a combustion tunnel forming part of said furnace and having a fuel inlet at one end and a gas outlet intermediate the ends of the tunnel, said furnace having a passage which discharges into the heating chamber and said 'outlet constituting the inlet of the said passage,

means at the fuel-inlet end of said tunnel for delivering thereinto for partial combustion therein a stream of finely divided fuel and less than suflicient air than is required to support complete combustion of said fuel, and means for discharging into said passage a stream of air for completing combustion of unburned fuel in the gases flowing from said tunnel by way of said passage.

2. A furnace comprising, in combination, a heating chamber, a combustion tunnel forming part of said furnace and having a fuel inlet at one end and a series of outlets intermediate the ends of the tunnel, said furnace having a plurality of passages discharging into the heating chamber and each outlet constituting the inlet of one of said passages, means at the inlet end of the tunnel for delivering thereinto for partial combustion therein a stream of finely divided fuel and less than suflicient air than is required to support complete combustion of the fuel, andmeans innecting said outlet with said chamber, means at the fuel inlet of said tunnel for delivering thereinto for partial combustion. a stream of atomized oil and less than sufllcient air than is required to support complete combustion of the oil, and

means for supplying to said passage a stream of air for completing combustion of unburned fuel in the gases flowing from said tunnel by way of said passage.

WILLIAM M. HEPBURN.

ERNEST G. or. CORIOLIS.

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