US2659424A

US2659424A - Combustion apparatus for furnaces

Info

Publication number: US2659424A
Application number: US180738A
Authority: US
Inventors: Ferguson William
Original assignee: NAT AIROIL BURNER Co Inc
Current assignee: NAT AIROIL BURNER Co Inc; NATIONAL AIROIL BURNER COMPANY Inc
Priority date: 1950-08-22
Filing date: 1950-08-22
Publication date: 1953-11-17
Anticipated expiration: 1970-11-17

Description

2 Sheets-Sheet 1 INVENTOR. WILLIAM FERGUSON FIG. 1

ATTORNEY Nov. 17, 1953 w. FERGUSON COMBUSTION APPARATUS FOR FURNACES Filed Aug. 22, 1950 NOV. 17, 1953 w, FERGUSON 2,659,424

COMBUSTION APPARATUS FOR FURNACES Filed Aug. 22, 1950 2 Sheets-Sheet 2 Firli INVENTOR. WILLIAM FERGUSON ATTORNEY Patented Nov. 17, 1953 2,659,424 COMBUSTION APPARATUS FOR FURNACES William Ferguson,

Philadelphia,

Pa., assignor to National Airoil Burner Company, Incorporated,

Philadelphia,

Pa., a corporation of Delaware Application August 22, 1950, Serial No. 180,738

2 Claims.

This invention relates to combustion apparatus for furnaces.

It has heretofore been proposed to provide center and single wall up-draft heaters, particularly for use in petroleum refinery processes, and in other heating processes where a substantial portion of the fuel heat is to be absorbed from flame radiation.

It has heretofore been proposed to provide alternative provisions for heating with oil or with gas firing, and one suitable form of apparatus for this purpose is shown in my prior United States Patent No. 2,512,319.

In a petroleum process furnace, it is not necessary to change either frequently, or rapidly, from oil to gas, or vice versa. In certain types of operation, oil is employed as a fuel only for bringing a cold furnace up to process temperature, after which a by-product gas from the process is available as fuel.

In other instances, natural gas may be obtained during certain seasons of the year, and it is only necessary to employ oil during part of the year, such as during a portion of the winter season. It is desirable, however, that provision be made for changing from one fuel to another Without discontinuing the process.

It is the principal object of the present invention, therefore, to provide a furnace, and combustion apparatus therefor, which is simple in construction and which may be readily employed, as desired, for the combustion of gaseous fuel or oil, upon changing of the burners.

It is a further object of the present invention to provide improved combustion apparatus in which suitable provisions are made, in the furnace, for burning gaseous fuel or oil and with substantially the same flame pattern with either type of fuel.

It is a further object of the present invention to provide an improved furnace, and burner construction therefor, in which a plurality of air passageways are included, one for primary air and one for secondary air, and in which the burner, of desired type for the fuel to be burned, is removably mounted in the primary air passageway.

It is a further object of the present invention to provide an improved furnace, and burner construction therefor, in Which provisions are made the admixture of spent combustion gases with the flame, thereby enhancing the character of combustion.

It is a further object of the present invention to provide an improved furnace, and burner construction therefor, in which the angle of flame incidence with respect to the bridge wall may be varied or adjusted as desired.

Other objects and advantageous features of the invention will be apparent from the specification and claims.

The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof, in which:

Figure 1 is a. vertical sectional view through a. furnace in accordance with the present invention, and illustrating the construction and arrangement of the burner for gaseous fuel firing;

Fig. 2 is a vertical sectional view taken approximately on the line 22 of Fig. 1;

Fig. 3 is a horizontal sectional view taken approximately on the line 33 of Fig. 1;

Fig. 4 is a view similar to Fig. 1 and illustrating the arrangement of the burner for oil firing;

Fig. 5 is a vertical sectional view taken approximately on line 55 of Fig. 4, and

Fig. 6 is a top plan view of an oil burner which may be employed in connection with the furnace of the present invention.

It should, of course, be understood, that the description and drawings herein are illustrative changes can be made in the structure disclosed zvithout departing from the spirit of the invenion.

Like numerals refer to like parts throughout the several views.

Referring now more particularly to the drawings, in which The furnace F is supported upon a foundation or horizontal floor I5, and, spaced upwardly therefrom, spaced horizontal walls I 6 and H are l5 and and extending forwardly from the a plurality of vertically extending walls e,eso,424

and the wall I6, constitutes a lower air duct, for purposes to be explained.

Similarly, in the space between the wall 16 and the wall l1, vertical walls are provided for each burner location. The space 2| between the I1 and the walls 26, constitutes an upper air duct, for purposes to be explained.

be understood that the furnace, in accordance with its size, will be provided with a plurality of burner locations each including a pair of upper and lower air ducts, in the space between the end walls l2 thereof, although for purposes of explanation only one pair of ducts has been illustrated.

The horizontal wall I6 is provided, at the wall H, with a burner block of refractory material, supported by the wall IS, the walls 18, and the wall ll, one burner block 25 being employed for each lower air duct l9. Each burner block 25 has a central opening or throat 26, inclined from the vertical, as illustrated in Figs. 1 and 3, and preferably at an angle of the order of 10 with respect to the wall H. The opening or throat 26, as illustrated in Figs. 1 and 3, is flaring from the lower to the upper ends to provide a flaring sheetlike flame pattern.

On the floor 16, in the lower air duct [9, a trackway is provided preferably comprising a channel section 21 mounted on a supporting plate 23 and fixedly secured to the floor 15. At the sides of the lower portion of the lower air duct IS, a plurality of channels 24 is provided, having track plates 26, which extend into the walls 18, carried thereon. The plates 28 extend longitudinally in the air duct is and provide an additional trackway.

At the front end of the lower air duct 13, and carried by the front wall 16, a door 36 is provided, preferably pivotally mounted to permit of outward swinging, and having an adjustable damper 3| thereon for admission of primary air. At the front end of the upper air duct 2!, an air door 32 is provided, preferably pivotally mounted to permit of outward swinging and having an adjustable damper 33 thereon for the admission of secondary air to the duct 2 I.

The front wall Ill, above the wall i1, may be provided with a sight port 34, for observing cornbustion conditions in the furnace.

As illustrated in Figs. 1 and 2, a gas burner 35 is provided for each lower air duct [9, removably mounted therein, and is preferably an inspirating gas burner of conventional Venturi type, and in which from to 100 per cent of the total air for combustion of gas, depending on the gas pressure, is drawn into a Venturi section 66. A gas supply pipe 31, preferably having a section 31a of flexible character, is provided and is connected to the Venturi section 36 at one end, an air inlet adjusting plate 36 being mounted on the Venturi section 36. The plate 38 is adapted to be positioned to determine the quantity of air admitted to the Venturi section 36, by a threaded rod 39, carried in a plate 40 mounted on the pipe 31, and capable of rotation by means of a handle 4|, for adjusting the air. A handle 42 is also mounted on the gas supply pipe 31 for positioning the gas burner 36 in the duct it.

The Venturi section 36 has, connected to the other end, a pipe nipple 43, of a length in accordance with the particular furnace, and on the outer end of the nipple 43, a manifold burner casing 44 is mounted and supported. The burner casing 44 preferably has lower flat wall portions 46 and a flat V-portion 46, for purposes to be explained.

On the upper end of the burner casing 44, a plurality of nozzles or burner tips 41 are mounted, preferably at an inclination corresponding to the angular disposition of the throat 26. The burner tips 41 with the throat 26 provide an approximately sheet-like flame.

0n the innermost end of the manifold 44 a stop 48 is provided which is adapted to abut against the wall i l for positioning the manifold 44 upon insertion in the lower air duct 19.

The gas burner 36 is supported, at the inner end thereof, by the engagement of the

wall portions

46 and 46 with the track plates 26 and the trackway 21, and is further supported by a bracket 49 in engagement with the Venturi section 36 and with the trackway 21.

As illustrated in Figs. 4, 5 and 6, an oil burner 56 is provided for each lower air duct is and removably mounted therein. Each of the oil burners 66 preferably includes an oil supply pipe 5| having a flexible section 6la, connected to any suitable source of oil to be fired and to a manifold 62. A control valve it is provided in the supply pipe 6| for controlling the quantity of oil supplied.

A fluid connection 64 is provided, having I, flexible section 54a, connected to a suitable source of atomizing fluid such as steam or air under pressure, and to the manifold 62. A control valve 55 is provided in the fluid connection 64 for controlling the quantity of atomizing fluid. The manifold 52 has a by-pass valve 66 therein. The manifold 62 has an oil delivery pipe 61 and an atomizing fluid delivery pipe 66 connected thereto, the other terminal ends of the

pipes

61 and 58 being connected by swivel Joints to a nosale pipe 59, which carries an atomizing nozzle 6| on its upper end. The

pipes

61 and 66 are preferably secured to suitable supports 6| and 62 which are slidable in the trackway provided by the channel 21. The support 62 is preferably provided with an upwardly extending plate It in which is carried a threaded adjusting rod 64. The rod 64 has a collar 66 in engagement with the nozzle pipe 63, and nuts 66 on the rod 64 permit of adjustment of the inclination of the nozzle pipe 59.

The nozzle pipe 69 is preferably adjusted to the desired angle of inclination and in conformity to the inclination of the throat 26 in the burner block 25, and is centered with respect thereto. The nozzle 66 and the throat are adapted to deliver a flaring sheet-like flame. The nozzle pipe 59 preferably has a bracket 61 secured thereto which is adapted to abut against the bridge will II and serve as a stop for positioning the burner 50 upon insertion into the lower air duct l3.

Extending upwardly from the wall [1, at the rear end thereof, and substantially in alinement with the front of the throat 26, a screen wall or dam 10 is provided, parallel to the bridge whll Ii, and preferably extending from one side wall 12 to the other side wall. The screen wall 1| is preferably made of refractory material and by deflecting upwardly any combustion gases falling within the furnace prevents the admixture thereof with the flame issuing from the throat 26. It will be noted that a trough 1| is provided in front of the rear wall I l, between the side walls 12, above the burner blocks 26, and to the rear of the rear ends of the air ducts 2| and of the screen wall 10.

The mode of operation will now be pointed out.

W n t is desired o unpLv heat to the furnace. and particularly to heat the wall I l for emitting to the casing 44 and the burner tips 41.

radiant heat, either of the

burners

35 or 50 may be employed in accordance with operating conditions.

If it is desired to utilize oil for fuel, the oil burner 50 is inserted in the lower air duct I9 and slid along the trackway 21 until the stop 61 comes into engagement with the wall I l The upper air duct 2| may be employed for ignition. Oil, supplied through the pipe and atomizing fluid supplied through the pipe 54, are delivered to the nozzle pipe 59 for discharge from the nozzle 60 in a flat pattern. A part or all of the air required for combustion may be introduced through the lower air duct I9, by suitable adjustment of the damper 3| in the door 30, and, if desired, a part of the air for combustion may be supplied through the upper air duct 2|, as determined by the positioning of the damper 33 in the door 32. The air entering the furnace through the upper air duct 2! mixes with the advancing stream passing from the throat 26.

If on the other hand, it is desired to heat the furnace with gas fuel, the oil burner 50 may be withdrawn by sliding the same outwardly along the trackway 21. The gas burner 35 may then be slid along the trackway 21 and the track plates 28 and to a position where the stop 48 engages the wall ll. Gas, supplied from the pipe 31 is delivered to the Venturi section 36 where air is inspirated in accordance with the positioning of the plate 38, and mixes with the gas for delivery The flame from the gas-air mixture discharged through the burner tips 41 passes upwardly through the throat 26. Air is admitted through the duct IS in accordance with the positioning of the damper 3! for supplying the additional air as required for combustion of the gas-air mixture. If desired, also, air may be admitted through the upper air duct 2| as determined by the positioning of the damper 33 for aiding in the completion of combustion of the gas-air mixture.

The flame from the oil burner 50 or from the gas burner 35 is caused to impinge on the bridge wall H, and thus radiates heat to the front wall absorption tubes [4. The hottest spot on the bridge wall H may be altered as to intensity and location by changing the angle of incidence of the flame to the bridge wall II. This can be accomplished by raising the outside end of either the oil burner 50 or the gas burner 35, the flexible connections 5m and 31a permitting of this adjustment while the burners are in operation.

It will also be noted that the upper air duct 2!, with its door 32, serves not only for the insertion of a lighting torch and for observation of the flame but that the door 32 is capable of functioning as an explosion relief door.

When the furnace is in operation, the flame and the bulk of the combustion gases impinge on and climb upwardly along the bridge wall ll, rise into the convection tube bank (not shown), and then pass into the stack. A small amount of the resultant spent gases may and often does descend within the furnace to cause a re-circulating effect. When this descending current of gas reaches the bottom of the furnace, which in the furnace shown comprises the upper surface of the wall I 1, it would normally tend to mix with the flame. Since the descending gas is composed principally of carbon dioxide and nitrogen, these inert gaseous components tend to delay ignition and retard combustion, causing a longer and smoky flame and a higher stack temperature.

The wall or dam 10 prevents the mixing of the re-circulated inert gases with the flame until after suflicient air has been supplied thereto through the ducts l9 and 2| to insure quick and complete combustion, with a minimum of excess air. The trough 1| to the rear of the wall or dam 10 with a plurality of burners .therealong aids in the ignition of the fuel and stabilizes the burning.

I claim:

1. In a furnace having vertical front, rear and side walls enclosing a furnace chamber, spaced walls at the lower portion of the furnace chamber providing a plurality of horizontally disposed inwardly extending upper and lower air ducts, a vertical screen wall extending from one side wall to the other side wall spaced forwardly from said rear wall and extending upwardly from said lower air ducts above said upper air ducts and into said furnace chamber to a height at least as great as the height of said upper air ducts to provide a transverse trough, said screen wall having openings therethrough for said upper air ducts, damper members for controlling the delivery of air into each of said ducts, a burner block between the inner ends of each of said lower ducts a discharge portion throat and said trough, ing the admixture of gases of combustion with the flame and with the air advancing upwardly from said ducts.

2. In a furnace having vertical front, rear and side walls enclosing a furnace chamber, spaced walls at the lower portion of the furnace chamber providing a plurality of horizontally disposed upper and lower air ducts, a vertical screen wall extending from one side wall to the other side wall spaced forwardly from said rear wall and extending upwardly from said lower air ducts above said upper air ducts and into said furnace chamber to a height at least as great as the height of said upper air ducts to provide a transverse trough, said screen wall having openings therethrough for said upper air ducts, members for controlling the delivery of air into each of said ducts, one of said spaced walls having an upwardly extending opening at the inner end of each of said lower ducts in communication with said trough, and a burner retractably mounted in each of said lower ducts and having a dis charge portion for alinement with said upwardly extending opening and said trough. said screen wall preventing the admixture of gases of combustion with the flame and with the air advancing upwardly from said ducts.

WILLIAM FERGUSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,447,337 Bitgood Mar. 6, 1923 1,785,583 Hawke Dec. 16, 1930 1,889,993 Leahy Dec. 2, 1932 1,953,275 Straitz Apr. 3, 1934 2,129,589 Praeger Sept. 6, 1938 2,219,363 Hoak Oct. 29, 1940 2,221,469 Brandt Nov. 12, 1940 2,512,319 Ferguson June 20, 1950