US2065533A - Furnace construction - Google Patents

Description

Dec; 29, 1936. j I v LEAHY 2,065,533

' FURNACE CONSTRUCTION Filed Oct. 19, 1931 6 Sheets-Sheet l Inventor A/lorneys Dec. 29, 1936. v AHY 2,065,533

' Y FURNACE CONSTRUCTION Filed Oct. 19, 1931 6 Sheets-Sheet 2 Dec. 29, 1936. v LEAHY 2,065,533

FURNACE CONSTRUCT ION Filed Oct. 19, 1931 6 Sheets-Sheet s- In 'uentor Dec. 29, 1936.. v LEAHY 2,065,533

FURNACE CONSTRUCTION Filed Oct. 19, 1931 6 Sheets-Sheet 4 Dec. 29, 1936. v LEAHY 2,065,533

FURNACE CONSTRUCTION Filed Oct. 19, 1931 6 Sheets-Sheet 5 Fatentecl Dec. 29, I936 UNITED STT oFFIQE' 4 Claims.

This invention relates to gas burning devices, and particularly to furnaces utilizing gas as fuel. An object of the invention is to automatically regulate the air supply to a gas furnace in proportion to the gas delivered.

Another object is to provide an automatic control equipment which may be readily adjusted for manual control in case of failure of the automatic control.

Another object is to prevent wastage of gas when the burner is operating under low gas pressure.

Another object is to provide draft doors for simultaneously regulating the admission of both cold and preheated air to the burner.

Another and more detailed object is to provide an automatic draft door, opening in response to the pressure of gas delivered to the burner, that will function to open the draft doors prior to the admission of. gas to the bLuner.

Another object is to improve the efiiciency of a gas burner.

Still another object is to simplify the assembly of a gas burner.

Other objects and advantages of the invention will be apparent from a detailed description of the invention when taken in conjunction with the drawings, in which Figure l is a front elevational view of a furnace employing three burners in accordance with my invention;

Figure 2 is a vertical cross section of a portion of a furnace showing the general installation of my burner in the furnace;

Figure 3 is a plan view, partly in section, of one of the burners disclosed in Figure 1;

Figure 4 is a vertical section in the plane IVIV in Figure 3;

Figure 5 is an enlarged sectional view of the door mechanism shown in Fig. 3, showing the doors in open position;

Figure 6 is a vertical section in the plane VIVI of Fig. 4;

Figure 7 is an elevational view of the inside end of the burner as it would appear from the interior of the furnace;

Figure 8 is a horizontal section looking down on one of the horizontal rows of tiles shown in Fig. 7;

Figure 9 is a detail end view of one of the tiles shown in Figs. 7 and 8;

Figure 10 is a detail side view of. one of the tiles shown in Figs. '7 and 8;

Figures 11, 12 and 13 are detail sections of different types of valves that may be employed in my burner;

Figure 14 is a section in the plane XIV-XIV of Fig. 11;

Figure 15 is an enlarged detail sectional View of one of the tiles and burner tips; and

Figure 16 is an end View of the burner tip shown in Fig. 15.

Referring to Fig. 2, a burner unit, designated generally at 3, is mounted in the front wall of a furnace setting. The front wall of. the furnace above the line i i and below the line 55, may be of any desired construction, the only requirement being that an opening be left between these lines in which to insert the burner. The gas burner is inserted in the lower part of the opening and comprises a wall of tiles 6, (a View of which as it appears from within the furnace is shown in Fig. '7), mounted one on top of the other to form a plurality of Venturi passages 1 leading into the combustion chamber 8. The detailed construction of the tiles forming these Venturi passages will be described later. Back of each Venturi passage i is positioned a burner nozzle 9 for delivering gas through the associated Venturi passage to the combustion chamber. Burner nozzles 9 are supported by a manifold II] which is connected through a pipe t3 and an automatic valve 19 to a gas pipe H. Draft doors it are placed back of the burners 9 for regulating the draft and admitting the optimum amount of air for complete combustion.

Oil burner I5 is positioned above the gas burner 3. This oil burner is not ordinarily used but is provided for emergency firing in case of failure of the gas supply to the gas burner 3. The space above the gas burner 3 and below the lowermost part of the standard burner setting (indicated by the line 5- in Fig. 2) is filled in with fire brick or other refractory material to prevent the passage of any air into the combustion chamber other than that passing in through or between Venturi tubes 1.

Gas burners in which a gas discharge jet, or a plurality of jets, are positioned back. of tubular mixing chambers of tile, are broadly old, being disclosed and claimed in my copending application Serial No. 21 L570, filed August 22, 1927, and issued as Patent No. 1,889,993 on December 6th, 1932. The present invention has to do with a furnace construction employing tiles of novel shape and burners of special design to increase the efficiency and facilitate assembly, and having special means for regulating the gas and air supplied to the burner.

Thus, referring to Figs. 3 and 4, the mixing chamber positioned in front of each gas nozzle 9 is formed by a tile having a Venturi shaped passage therethrough. This Venturi shaped passage serves to facilitate the mixing of the gas with the air which. is drawn in about the gas jet so that substantially complete combustion of the gas is obtained without the use of an excessive amount of air, which would tend to decrease the overall efiiciency of the furnace by unnecessary dilution of the hot gases.

As shown in Figs. 7 to 10, each burner tile 6, although having a Venturi shaped passage therethrough, is of the same outside dimensions from end to end and is roughly octagonal in outside shape. When assembled, as shown in Fig. 7, all the tiles'are in contact with each other and are mutually self-supporting. However, to prevent any accidental longitudinal displacement of any tube or tubes, and to brace the furnace in which the tiles are set, horizontal supporting rods |8 are provided between adjacent horizontal rows of tiles, each tile being provided with transverse grooves IS in its top and bottom which engage with the rods I8. If desired, the rods i8 may be extended vertically between vertical rows of tile.

Since the grooves are substantially semi-cylindrical in shape, the rods l8 fit snugly therein and at the same time there is actual contact between the tiles in each row. A particular advantage of this form of construction is that tiles may be removed and replaced from the rear of the burner without dismantling the whole assembly. Likewise, they may be removed from the front or furnace side of the burner, if desired. In either case, the removal is accomplished by simply grasping the tile and twisting it one-eighth of a revolution, thereby disengaging the grooves |9 from rods 8 and withdrawing the tile. As shown to best advantage in Fig. 9, the outer face 28 of each tile is slightly rounded so that each tile can be twisted without displacing the surrounding tile to any appreciable extent. The surface 26, how ever, is sufficiently fiat to retain the tile in position except when it is purposely twisted to remove it.

Although mixing tubes of the type described can be used with various types of gas nozzles, I prefer to use a nozzle of the type disclosed in Figs. and 16 in which the gas is mixed with a certain amount of air before being discharged into the hollow tile.

Referring to Fig. 15, each burner nozzle 9 comprises a substantially cylindrical tip body 90: having a plurality of Venturi openings 8| extending therethrough. In the tip shown, three passages have been provided, but more may be used if it is desired to increase the capacity. Body 9a is mounted infront of a multi-jet nozzle 82 having a plurality of jets 83, each of which is positioned within the end of one of the Venturi tubes 8|.

The body So is provided with a central opening 84 into which a centering projection 85 on nozzle 82 fits. Projection 85 serves to center the burner tip 90. with respect to nozzle member 82 and a shoulder shown at the base of projection 85 serves to space the burner tip from the base member to permit the entry of air into jet passage 8| around the associated jets 83. The member 9a may be secured to the base member 82 by means of a pin 86 passing through the member 3a and the projection 85.

As pointed out above, the discharge of gas from the burner jets 83 through the Venturi openings 8| and I causes the suction through the tubes,

along with the gas, of the air necessary for combustion. This air is drawn in through the space between the burner nozzles and the tiles, and the volume of air supplied is controlled in accordance with the present invention by a pair of doors 2|.

Referring to Fig. 3, these doors are supported on hinges 22 at each side. In closed position, as shown in Fig. 3, the doors fit snugly against wall 23 so that there is no passage opening from the front of the furnace to the burners. Intake passages are also provided in the floor of the burner compartment for supplying heated air thereto from a pasage 24 (see Fig. 2) extending below the furnace, and passages 24a are provided in the top of the burner compartment for supplying heated air thereto from a passage 25a extending between the I-beams 2517; but these passages 25 and 24a are normally closed by horizontal plates 26 which are secured to doors 2|. Hence when the doors 2| are in the position shown in Fig. 3, all air passages leading into the burner compartment are closed. When gas is admitted to the burners, doors 2| are automatically opened to admit air in proportion to the gas being delivered to the burners by the automatic valve l3, the construction and operation of which will now be described.

Referring to Fig. 4, the automatic valve comprises a diaphragm 21 of flexible material clamped between two bell-shaped casing members 28 and 29 and forming a gas-tight partition there between. Attached to the center of diaphragm 21 and extending therebelow, is a connecting member 38 having attached thereto a valve 3| which seats in a seat member 32. Attached to the upper side of diaphragm 21, and extending thereabove is a member 33 to which is connected, by a link 34, a lever 35. Lever is pivoted to rotate about a pin 35 as a fulcrum and has hingedly attached thereto a link 31 which is pivotally connected at its other end to a collar 38 sliding on a rod 39 which projects from the framework ID of the burner. A cross arm is adjustably attached to collar 38 and is connected at its outer ends by links 4| to the doors 2|. Hence it will be seen that raising diaphragm 21 rotates lever 35 about pivot 36, withdraws the collar 38 outwardly along the rod 39, thus shifting cross arm 48 outwardly and opening doors 2|.

In operation, when no gas is admitted to supply pipe diaphragm 21 is held in its lowermost position, as shown in Fig. 4, by a weight 42 on the lever 35, and doors 2| are held in closed position. When gas is admitted to supply pipe II, it flows into the space below diaphragm 21 and if the pressure is sufficient lifts diaphragm 21, thus raising valve 3| from seat 32 and admitting gas to the burner nozzles 9, and simultaneously lifting member 33, link 34 and shifting lever 35 to withdraw collar 38 outwardly along rod 39 and open doors 2| to admit air to the burner. Since the end of the lever 35 on which weight 42 is mounted is tilted downwardly when diaphragm 2'! is in its lowermost position, it is raised and approaches the horizontal position as the diaphragm rises. Hence weight 42 on lever 35 exerts a greater resisting force on lever 35 as the diaphragm 21 lifts. As a result, lever 35 and doors 2| connected therewith assume a position of equilibrium when the gas pressure beneath diaphragm 21 is just sufficient to overcome the downward force exerted by weight 42. If the gas pressure increases, the doors are opened further and if the gas pressure decreases, the doors are closed proportionately.

Thus the air supply is automatically regulated in proportion to the gas pressure applied to the burner.

' It should be noted that the plates 26 are attached to doors 2| and open therewith, as shown in Fig. 5, to admit preheated air from passages 24 and 25a, through openings 25 and 24a. Thus a single moving element, that is, each door 2| and the plate 26 attached thereto, serves to control the admission of both preheated and cool air.

It is desirable, when gas is admitted to supply pipe II, that the doors 2| open to admit air to the burners before gas is actually discharged from the nozzles 9. I therefore provide a 10st motion device between diaphragm 2i and valve 3| that will permit the diaphragm to rise slightly and partly open the doors 2| before valve 3| lifts from its seat 32 and admits gas to the burners. I have developed various mechanisms for achieving this purpose, three of which are illustrated in Figs. 11, 12 and 13.

Referring to Fig. 11, the member 30, extending upwardly from valve 3|, is attached to diaphragm 21 by a clamp member 44. Thus member 44 fits against the lower side of diaphragm 21 and is secured thereto by a threaded stud 45 (see Fig. 4),

extending from the lowermost end of member 33, stud 45 screwing into member 44 and clamping the diaphragm 21 therebetween. Member 30, projecting upwardly from valve 3| has a vertical slot 46 in its uppermost end into which a tongue 41 extends from member 44. Tongue 41 also has a vertical slot 49 therein and a pin 48 passing through the upper end of member 36 engages the slot in tongue 41. Since the vertical dimension of slot 49 is greater than the diameter of pin 48, member 44 attached to diaphragm 21 can rise through a distance equal to the difference in the diameter of pin 48 and the length of slot 46 before it lifts member 30 and valve 3|. In this embodiment, the valve 3| has a tapered face 50 which seats against a tapered face on the valve seat 32, To further delay the admission of any appreciable amount of gas until the diaphragm 21 has risen some distance, a downwardly projecting substantially cylindrical skirt is provided on the valve 3|. The effective length of the cylindrical portion extending below the valve seat 32 may be varied by raising or lowering the skirt portion 5| relative to the valve proper 3|. Thus, as shown, skirt portion 5| is provided with a downwardly extending tubular extension 52 which is hollow and threaded on its inner circumference. Valve member 3| is provided with a downwardly extending stem 53 which is threaded exteriorly and is adapted to screw into the upper end of the tubular extension 52. The lower end of stem 53 is split into four segments, as shown in the cross sectional view of Fig. 14, so that by screwing a pointed pin 54 up into the lower end of tube 52, the lower end of the threaded stem 53 may be spread and locked firmly with respect to the tubular member 52. The lower ends of tubular members 52 and the locking pin 54 are squared to permit their being turned relative to each other by means of wrenches.

The valve just described provides adjustment of the degree of opening of doors 2| before the admittance of appreciable amounts of gas, by means of the adjustable skirt 5|. In the valve shown in Fig. 12, adjustment is provided by regulating the degree of play in the lost motion connection between the valve 3| and the member 44 attached to diaphragm 21. In this arrangement, the valve 3| is provided with an inner member 55 which is movable vertically within a hollow stem 56 of the valve and projects from the top of a tubular extension 51 on the valve. Member 55 is provided at its top with a shoulder 58 which fits loosely in an opening 59 in the bottom of member 44 and is secured therein by a retaining nut 60 which is screwed onto the lower end of member 44. With this arrangement, when the diaphragm is in the lowermost position, retaining nut 60, attached to member 44, rests on the top of the tubular extension 51 on valve 3|. When member 44 is lifted by diaphragm 21, it moves a certain distance before engaging the shoulder 58 on rod 55 and hence introduces the desired lost motion between the diaphragm 21 and valve 3|. The amount of lost motion may be varied by screwing rod 55 in or out of the stem 56. A slot 6| is provided in the lower end of rod 55 to permit turning it with a screw-driver and a lock-nut 62 is provided to lock it into position when it has been properly set. It should be noted that since the lower end of rod 55 and lock-nut 62 projects below the sleeve 63 (referring to Fig. 4), it may be adjusted without disassembling the valve.

In Fig. 13 is illustrated still another form of valve incorporating a lost motion device. In this arrangement, the member 44 is secured, by a nut 63a, to a plunger 64 which extends entirely through the body of the valve 3|. Surrounding plunger 64 and threaded thereon at the lower end is a bushing 65 slidably mounted within a tubular stem 66 extending downward from the skirt portion 61 of the valve. Skirt portion 61 is threaded onto the valve 3| and is locked into position by a detent 68 fitting into a depression in member 3|. In operation, member 44, plunger 64, and sleeve 65 rise with the diaphragm 27, independently of the valve 3| until the upper end of sleeve 65 strikes a shoulder 69 on valve 3| and lifts the valve from its seat. In this type of valve the amount of lost motion is controlled by turning sleeve 65 and thus screwing it in or out with respect to plunger 64. Thus if sleeve 65 is screwed out it must rise a greater distance before contacting with shoulder 69. When set at the proper point, it is locked in position by a lock-nut 10.

It sometimes happens that the flexible diaphragm 21 becomes leaky, under which condition there is objectionable leakage of gas into the atmosphere and the automatic mechanism may not function to open the draft door 2|. I therefore provide means for altering the automatic valve so that in case of necessity the draft door can be operated by manual control. Thus, referring to Fig. 4, a cap it is provided on the lower end of the valve housing 63, and a stud i2 is threaded into the cap. By screwing stud 72 into cap 1| the valve 3| and diaphragm 2'! may be forced upward until a shoulder 53, having a ground, beveled edge, seats against a ground, beveled seat 54, formed in the upper case member 28 of the diaphragm chamber. In this position the valve 3| is open to permit gas to flow from the supply pipe to the burner through pipe 43, and the opening about the stem 33 is sealed by shoulder 73 to prevent the leakage of gas at that point. The link 37 may then be disconnected from the sleeve 38 and the draft regulated by manually sliding the sleeve 38 along rod 39 to give any desired opening of the doors 2 i.

It is to be understood that under all conditions of operation the supply of gas to the burners is controlled by a valve inserted at some point between the gas pipe II and the source of supply. Thus referring to Fig. 1, gas is supplied to the pipe H associated with each burner from 75 a main I I4 through a pipe I2, an emergency valve II I and a control valve I III. In normal operation the valve I I I is wide open andvalve I I0 is adjusted to control the heat by admitting more or less gas to the pipe I I,

In automatic operation, the draft door opening obtained in response to a given movement of diaphragm 21 may be regulated by connecting the link 31 to different points along lever 35, and to facilitate such adjustment lever 35 is curved and slotted as shown in Fig. 4.

As shown in Fig. "I, each burner usually comprises about eighteen jets, although the number may be varied, depending upon the size of the furnace opening, and I find it convenient to utilize one of the center jets in the lower bank as a pilot burner and supply it from a separate gas line I5 (Fig. 3). It is also desirable to supply another jet, preferably one adjacent the pilot jet, by a separate passage 16 leading from supply line II ahead of valve I3. This is advantageous for the following reasons: When the furnace is being operated at a low capacity, the gas supplied to pipe II may be almost out off, so that although there is sufficient pressure to lift the diaphragm 21 and open valve 3|, the gas flowing from each nozzle 9 may have so little velocity that it does not draw in sufficient air for its proper combustion, or it may not ignite at all. Thus thereis wastage of gas. By providing the by-pass F6 from supply pipe II to one only of nozzles 9, any slow flow of gas through pipe II passes directly through by-pass I6 and can not build up enough pressure against diaphragm 21 to open valve 3!. The net result is that when the supply of gas to line II is almost, but not quite out off, what gas does enter the burner is burned efficiently at one burner instead of wasting at low pressure from all the burners.

The pilot and auxiliary burners are provided with larger flanges than the other burners, as shown in Figs. 3 and 4. This is to reduce the amount of air drawn into the Venturi tubes of those burners, and reduce the possibility of the flames from those burners being blown out.

It is to be noted that when doors ZI are only partly open they admit air directly to the center of the burner. Ihis is desirable because it is round difficult in practice to supply sufficient air to the central part of the burner, without supplying an excess of air to the outer edges.

What I claim is:

1. In a furnace construction, a combustion chamber, means for supplying gaseous fuel thereto comprising a supply line, a. valve in said supply line, a movable diaphragm, one side of which is exposed to the pressure of gas in said supply line ahead of said valve, a connection between said diaphragm and said valve whereby motion of said diaphragm in response to gas pressure exerted thereon opens said valve, means defining a passage for admitting air to said combustion chamber, a door in said passage, and means connecting said door to said diaphragm for opening said door in response to gas pressure in said line. V

2. In a furnace construction, a combustion chamber, means for supplying gaseous fuel thereto comprising a gas line, a valve in said gas line, means for supplying air to said combustion chamber comprising a passage having a door therein, a movable diaphragm, one side of which is exposed to the pressure of gas in said supply line ahead of said valve, means connecting said diaphragm and said door for opening said door in response to gas pressure on said diaphragm, and means connecting said diaphragm to said valve comprising a lost motion connection for opening said valve subsequent to the opening of said door.

3. In a furnace construction, a combustion chamber, a plurality of burners for supplying a mixture of gaseous fuel and air to said combustion chamber, a supply line for supplying gaseous fuel to said burners, a control valve in said supply line, a second valve in said supply line positioned between said control valve and said burners, a movable diaphragm one side of which is exposed to the pressure of gas in said supply line between said control valve and said second valve, a connection between said diaphragm and said second valve whereby motion of said diaphragm in response to gas pressure exerted thereon opens said second valve, means defining a passage for admitting air to said combustion chamber, a door in said passage, means connecting said door to said diaphragm for opening said door in response to gas pressure in said line between said control valve and said second valve, an auxiliary heating burner for supplying a mixture of gaseous fuel and air to said combustion chamber when only a small fire is to be maintained, and a by-pass gas line for supplying gas from said first gas line at a point between said control valve and said second valve to said auxiliary burner, whereby all gas supplied by said gas line is delivered to said auxiliary burner when the gas pressure in said line between said control valve and said second valve is insufficient to open said second valve.

, 4. In a furnace construction, a combustion chamber, a plurality of heating burners for supplying gaseous fuel to said combustion chamber, means comprising a gas line for supplying gas to some of said burners, a control valve in said gas line, and a second valve in said gas line between said control valve and said burners, means comprising a diaphragm one side of which is at all times exposed to gas pressure in said line between said control valve and said second valve for opening said second valve, and a by-pass gas line for supplying gas from said gas line at a point between said control valve and said second valve to another of said heating burners whereby all gas supplied by said gas line through said control valve is delivered to said other burner when the gas pressure in said line ahead of said second valve is insufiicient to open said second valve.

HERBERT V. LEAHY.

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