US1576753A - Furnace control - Google Patents

Description

Maren 16 1926. 1,576,753

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E. MCLEAN FURNAGE CONTROL Original Filed June 25, 1920 March 16,1926.l

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E. MGLEAN FURNACE CONTROL Original Filed June 25, 1920 4 Sheets-5heet :5

BY Y 5 v LM A TTORNEY March 16 1926.

E. MCLEAN FUnNAcE CONTROL Original Filed June 25, 1920 4 Sheets-Sheet 4 'INI/ENTOR.

WITNESS:

4 l a if ATTORNEYS Patented Mar. 16, 1926.

UNITED STATES PATENT OFFICE.

EMBURY MCLEAN, OF BROOKLYN, NEW' YORK, ASSIGNOR TO THE ENGINEER COM- PANY, or new YonK, N. Y.,

A CORPORATION OF NEW YORK.

FURNACE CONTROL.

Application led June 25, 1920, Serial No. 391,779. Renewed April 22, 1925.

T all whomA t may concern.'

Be it known that I. EMBURY MCLEAN, a citizen of the United States, and resident of the city of New York, borough of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Furnace Controls, of which the following is a specification.

My invention relates to new and useful improvements in the control of combustion in fluid-fuel-burning` furnaces, and more particularly relates to a method for controlling the elements of combustion in such a furnace.

One object of the invention, among others, to be described hereinafter, is to provide an improved method for controlling the amount of air supplied to a fluid-fuel-burning furnace so that said air may be varied to meet the requirements of combustion, the control being effected by the rate of flow.

The invention also contemplates an improved method for controlling the air fed to the furnace in such manner that a uniform mixture of the fluid fuel and air is obtained for the varying conditions of the flamein the furnace chamber.

The invention consists in the improved method to be more fully described hereinafter, and the novelty of which will be particularly pointed out and distinctly claimed.

I have fully and clearly illustrated certain apparatus for practising the invention in the accompanying' drawings to be taken as a part hereof, and wherein:

Figure 1 is a view in side elevation, partly in section, of a steam boiler furnace for practising said invention.

Fig. 2 is a, horizontal section taken through Fig. 1, with portions broken away to show other parts in section, and other parts being shown in plan.

Fig. 3 is a view in side elevation, partly in section. of a steam boiler furnace showing another embodiment of my invention.

Fig. 4l is a transverse section through a controlling device employed in the embodiment shown in Fig. 3, wherein said device is operated by the rate of flow of oil fed to the burner to control the air supplied for combustion to the furnace.

Fig. 5 is a plan view of the lower portion or h alf of the device shown in Fig. 4.

Fig. 6 is a top plan view, partly in section, of the upper portion or half of the element shown in Fig. 4l.

Fig. 7 is a vertical central section through the pressure controlled device constituting one of the elements of the form of the invention shown in Figs. 1 and 2, to control the air supplied to the furnace for combustion, by the pressure of the fluid fuel fed to a burner.

Fig 8 is a top plan View, partly in section, showing in detail certain of the elements in Fig. 7.

Fig. 9 is a vertical longitudinal section through a regulator for controlling the quantity of fluid fuel fed to the furnace in accordance with the steam pressure of the boiler, and also to control the amount of atomizing steam fed to the burner to atomize the oil flowing therefrom into the furnace.

Fig. 10 is a detail view of a portion of the inlet air damper connections shown in Figs. 1, 2 and 3.

Fig. 1l is a view in front elevation, partly in section, of a regulator for controlling the furnace gas pressure.

Fig. 12 is a central vertical section of the regulator shown in Fig. 11, and

Fig. 13 is a detail view, partl in section, showing the arrangement of ampers for controlling access of air to the furnace chamber.

I will first describe in detail the apparatus shown in the accompanying drawings and then, in connection with a description of the operation thereof, setforth the novel method, a l of which constitute my invention.

Referring to the drawings by characters of reference, and particularly to Figs. 1 and 2, 1 designates a boiler furnace of any wellknown construction, and to which my invention is applicable, it being understood that said furnace is shown merely by way of example, and that my invention is not limited to the type or construction of said furnace.

In the type of boiler furnace shown, said furnace is provided with side walls 2, 2. front wall 3, a rear wall 4t, and a bridge wall 5, which, together with the fronit and side walls form a furnace chamber 7, the top of the furnace chamber being formed by the lower surface of the boiler or boiler tubes (not shown), an upper steam drum of which is shownl at 6. Iithi'n the furnace chamber and spaced vertically from the bottom or floor of the furnace, is a substantially horizontal partition 8 extending from the front wall to the bridge wall, and from one side wall to the other, so as to provide an air inlet chamber 9 beneath said partition. An area or portion of said partition is of open-work or checker-work structure so as to provide a plurality of openings through which air may flow from the chant ber 9 to the furnace chamber 7, said area being substantially coextensive with the size of the flame when the burner is working at high pressure. By reference to Fig. 2, it will be seen that the checker-work portion is of flaring form, the tapering sides of which are provided by imperforate portions 11 of said partitions at the forward corners of the furnace, the outwardly inclined edges 12 of said imperforate portions defining the forward boundaries of the flaring checker-work portion. In the present embodiment the said fia-ring edges 12 extend from a point adjacent the center of the front wall to a point substantially midway the length of the side walls of the furnace, so that the checker-work extends from said boundaries rearwards to the bridge wall lengthwise of the furnace, and the entire width of the furnace at poinrts in rear of the points at which said boundaries merge with said side walls. It will be seen that the area of the open-work portion of the partition 8 conforms substantially to the maximum form of the flame in the furnace chamber.

The furnace is also provided with a suitable outlet stach 18 through which the products of combustion find exit, the area of the passage through the stack being controlled by a suitable damper 14 pivoted, as at 15, on the stack, in any suitable manner.

The means for supplying fiuid fuel to the furnace consists of a burner or nozzle 16 located preferably in the front portion of the furnace chamber above the partit-ion 8 and central of the transverse width of th-e furnace chamber, and over the forward portion of the open-work area of said partition. This burner or nozzle may be of any well-known type for feeding fluid fuel in admiXture with an atom-izing element, such as steam or air, to the furnace chamber. Oil or other fluid fuel is fed to the said burner from a pump 17 through a pipe 18 controlled by a shut-od valve 19, and steam under pressure from the boiler is fed to the burner through a pipe 20, the latter containing valves 21, 21. The quantity of fluid fuel and atomizing steam flowing to the burner through pipes 18, 20 is controlled by a regulator, shown generally at 22 in Fig. 1, and specifically in Fig. 9, operating valves in the fluid fuel and steam pipes, the valve in th-e latter being located between the hand-valves 2l. rI his regulator ma),Y be of any suitable type which can be adjusted so as to automatically regulate the amount of oil fed to the burner in accordance with the steam pressure of the boiler.v and also the quantity of steam fed to the burner to atomize the oil. In the drawingsl (see Fig. 9), I have shown a well-known type of regulator for this lliur'pose, the same consisting of a cylindrical chamber having diaphragm heads 24, 25 sealing the chamber, the latter being connected by a pipe 26 with a source of Isteam at boiler pressure. Over the diaphragm 24 is a plate 27 supporting a frame 28 connected on its upper end, 1n any suitable manner, to a valve body or casing 29 located in the steam pipe 20 between the valves 2l, as stated, said body having a valve scat 8O with. which cooperates a valve 3l connected to a stein 32 guided by a stulling box 33. and a sleeve 34, the latter being threaded in the said frame 28, as at The valve stem 32 is connected to a plate 36 resting on the diaphragm 24, heretofore described. Surrounding the stein 32 is an expansion spring 87, the ends of which respectively abut the said plate 86 and an abutment 88 resting against the lower end of said sleeve 34, the function of said spring being to urge the valve 31 11nward open position in opposition to the pressure of steam within the chamber 2), The pressure of the spring 87 may be regulated by adjusting said screw 34 and consequcntly the position of the said plate 258 so that the latter may be adjusted relative to the plate 36 to compress er relieve the compression of the spring 87 A construction similar to the above is provided for regulating the quantity of fluid fuel, and includes a valve body or casing S9 in the pipe 18 having a seat 40 having a passage controlled by a valve 41, the latter being connected to a stein 42 guided through a stuffing box 43 corresponding to the stuffing box 33, heretofore described, and supported by a frame 44 supported by a plate 45, similar to the plate 27, heretofore described. The stem 42 is guided through an adjustable screw 46 threaded through a portion of the frame` as at 47, and carrying an abutment plate 48 against which abuts one end of a spring 49 coiled about the said stein 42, and the other end of which is connected to the plate 50 on the outer face of the diaphragm 25. This spring normally urges the valve 41 towards open position in opposition to the steam pressure within the chamber 23 tending to close the valve. By adlll) justment of the elements 34- and 47, heretofore described, the relative area of the opening in the steam pipe and the oil supply pipe may be regulated in accordance with a given steam pressure in order to determine the amounts or quantities of oil and steam fed to the boiler.

Connected to the oil supply pipe 18, as at 51, is a pipe 52 leading to a regulator, shown generally at 53 in Figs. 1 and 2, which is actuated in accordance with the pressure of the oil in said pipe 18 to regulate the dampers, hereinafter described, so that the quantity of air fed to the furnace will be varied in accordance with a characteristic of flow of oil fed to the boiler, in this instance, the characteristic of flow being the pressure of such oil. Said regulator' will be specifically described hereinafter.

The fluid fuel fed from the burner or nozzle 16 to the furnace chamber 7 being under pressure is in the form which results in a iianic which is either substantially cone-shaped or fan-shaped, according to the type of burner employed. It is desirable that the air entering the furnace chamber be admitted over an area conforming as nearly as possible to the form or area of the flame in order that the best results be obtained as regards complete combustion. My invention provides an ellicient means for regulating the area of air distribution, and for this purpose I provide means for controlling the area of the open-work portion of the partition 8 through which the air flows from the space 9 to the chamber 7, so that said area will conform substantially to the area of the flame, and will supply a quantity of air desirable for combustion. For this purpose I divide the chamber 9 into a plurality of air chambers, each preferably having an independent air supply, and having outlets upwards into the furnace chan'iber through that portion of the openworlt partition 8 in'iniediately over the particular chamber beneath said partition. In the present einliodin'lent, I preferably divide chamber 9 into three such air supply chambers, and do this by providing two vertical partitions 511 extending in a general direction lengthwise of the furnace and having their inner ends closely adjacent each other to provide a passage, as at 55, adjacent the nozzle 16 from which point they Hare outwards to the point where they abut or join the bridge wall 5, as shown at 56. The inner ends of said partitions 54. are connected by outwardly directed end partitions 57 with the side walls of the furnace, respectively. The partitions 54 and 57 eX- tend from the floor of the furnace to the underside of the partition 8, so as to form three separate independent chambers. It

will be seen that by the arrangement of partitions 54 and 57, the space beneath the partition 8 is divided into a. central flaring chamber 58 and two wing compartments 59, said central chamber being approximately the shape and area of the flame when the burner is being operated at a relatively low pressure, and the air through the open-work portion of the partition 8 from the wing compartments 59, 59 being available for an increased area of the flame when the burner is operated at relatively high pressures. It will thus be seen that I am able to control the area of air supplied through the partition 8 in order to conform substantially to the area of the fiame when the burner is operated at different pressures. As stated, I preL-"erably provide independent means for controlling the supply of air to each of the chambers and 59, such means preferably consisting of dampers 60, 61, 62, the same being pivoted` respectively in the passage between the inner ends of the walls 54:, and the dampers 61 and 62 being pivoted in openings 63 and 64 in the said partitions 57. In the present embodiment, I provide means for automatically operating the said dampers in order to control the supply of air to the chambers 58 and 59, in accordance with a characteristic of the flow of oil to the burner. I desire it understood, however, that my invention, as regards the method of air distribution to conform to the area of the fiame, is not limited to any particular means for controlling the amount of such supply, as such amounts may be regulated by either automatic or hand-control. In the present embodiment where the dampers are automatically controlled, the dampers 61, 62 are mounted on horizontal shafts 65 mounted in suitable bearings, carrying levers 66, each of which is provided on its end with a weight 67, said weight normally tending to rotate the shafts to move the dan'ipers to open position to increase the amount of air fed to the chambers 59. The damper is mounted on a shaft 68 connected by a universal joint 69 with one or both of the said shafts 65, so as to move all three of said dempers in unison. The connection between the central damper 60 and the dainpers 61 and 62 is so adjusted that when the dampers 61 and 62 are closed, the central damper will be partially open, so as to admit air to the central chamber 58, but as the dempers 61 and 62 are moved toward open position, the damper 60 will be moved to increase the area of the opening controlled thereby to the chamber 5S. Air is admitted to the front portion of the furnace beneath the partition 8, and in front of the walls 57, through an air duct 70 in the front wall of the furnace. The duct 70 may be open to the atmosphere, shown, or be connected to a source of draft under pressure, as for example, a blower. I will hereinafter describe two forms of llt) liu

automatic means for controlling the said dainpers.

The controller 53, heretofore mentioned, operates a flexible connection 71 extending upwards over a sprocket 72 on one end of a horizontal shaft 73 in suitable bearings above the furnace, and thence downwards and is connected to one of the said levers 66. On the opposite end of the shaft 73 is a sprocket 74 over which extends a sprocket chain 75, one end of which is connected to the other lever 66, the other end of said chain bearing a weight 76, by means of which said chain is maintained taut. The arrangement is such that when the pressure of oil flowing to the burner is increased, said regulator 53 will be actuated to move the dampers to increase the quantity of air flowing to the air distributing chambers, whereas, on the other hand, upon the reduction of the pressure of oil fed to the burner, said regulator will operate to cause said dampers to be moved toward closed position to reduce the amount of air fed to the distributing chambers in accordance with the pressure of oil fed to the burner, so that the air supplied and distribution thereof is maintained commensurate for proper combustion. The regulator 53 may be of any well-known type which will serve the purpose and perform the functions set forth,but I prefer to employ what is known on the market as the Mason compensating regulator which is shown in detail in Figs. 7 and 8 of the drawings. As this construction is well-known, l do not deem it necessary to describe the same with particularity, but in order that the operation thereof may be understood I brietiy describe the construction as follow/S177 designates aplate having a diaphragm chamber closed at its upper portion by a flexible diaphragm 78 upon which rests a plate 79 upon which is mounted a fulcrum 80. The chamber 77Il formed by the plate 77 and the diaphragm 78 is connected to a pipe 52, heretofore described. Supported over the diaphragm chamber is aframe 81 supporting a downwardly directed knife-edge fulcrum 82 against which bears a fulcrum pin 83 on one end of a lever 84, said lever also having a fulcrum bearing as at 85 on the said fulcrum 80, so that said lever responds to movements of the said diaphragm 78 in accordance with variations of pressure in the diaphragm chamber 77a. The outer end of the lever 84 carries a weight 85 opposing the pressure exerted by the diaph 1agm 78 tending to lift the lever 84. This lever 84 controls the flow, of a. motive fluid to a motor cylinder for operating the chain or flexible connection 71, heretofore described. This motor cylinder is shown at 86 containing a sliding piston 87 mounted on a piston rod 88 extending through a stuffing box 89 in one end of the cylinder and connected, as at 90, to the said chain 71. Within the cylinder 86 are inlet ducts 91, 92, opening on opposite sides of the piston 87 and communicating through ducts 93, 94 with a valveway 95, within which reciproeates a double-headed piston valve 96 on a stem 97 extending through a stuffing box 98 on the casing of the piston valve and operable by means of the lever 84, as will be presently described.

Entering the valveway 95 is a supply opening 99 leading from al suitable source of fluid pressure, for example, water, an l. above and below the piston valve 96 are exhaust chambers 100, 100a leading to an exit or exhaust 1001), said piston valve 96 being operable to control the flow from the inlet 99, and to the exhaust chambers relative to the said cylinder 86. lhenaid piston valve is in the position shown iii-Fig. 7, flow of motive fluid is cut off both to and from the cylinder 86, the heads closing the ports 93, 94. Then the piston valve moves downwards to uncover the port 93, flow will be permitted from the inlet 99 between the heads of the piston valve 96 to the passage 94, and thence through the passage 92 to the cylindcr 86 below the piston 87, and at the same time. the exhaust 100b will be connected to the upper part of the cylinder 86 through the chamber 100 and the space above the upper head of the double-headed piston valve 96. On the other hand, when the piston valve 96 moves upward, the upper portion ot' the cylinder 86 is connected to the inlet through the passage 93 and the space between tlie heads of the piston valve 96, and the lower portion of the cylinder is connected to the exhaust through the duct 94, the chamber 100a and the duct or by-pass 101, shown in dotted lines leading to the exhaust 100. The piston rod 97 is pivotally connected at its upper end, as at 102, to one end of a lever 103, the opposite end of which is slotted as at 104 (see Fig. 8), and receives an eccentric pin 105 on a shaft 106 having bearing, as at 107, in a bracket 108 on the cylinder 86, the opposite end of said shaft 106 being rigidly connected to a lever 108 which, in turn, is pivoted, as at 109, to one end of a link 110, the other end of which is pivoted, as at 111, to the piston rod 88. The lever 103 is connected, as at 112` to one end of a link 113, the other end of which is connccted, as at 114, to the lever 84. lVhen the lever 84 raises the piston valve 96, pressure is admitted to the upper end ofthe cylinder, as described, to move the piston 87 downwards: this causes a downward movement of the link 110 which lowers the lever 1083, and through connections 104, 105 raises the adjacent end of the lever 103, which, acting on the connection 112 as a fulcrum, moves the double-headed piston valve 96 towards position to shut off the ports 93, 94. Upon a reduction of pressure in the chamber 77",

the weight 85 moves the lever 84 downwards to thereby control the flow to admit pressure to the lower portion of the cylinder 86, causing the compensating mechanism to operate in the opposite direction Jfrom that just described. In designing this regulator, length of leverage between the pin 105 and the shaft 106 can be so proportioned that the regulator may be caused to operate over any desired range of pressures.

The invention also includes control of the furnace gas pressure. so that the latter is maintained substantially7 constant for varying rates of air supply, this being effected by controlling the outflow of gases from the furnace. In order to accomplish this result, I provide the furnace with what is known as a balanced draft regulation operating in accordance with the principle described in my prior United States Letters Patent No. 817,438, dated April 10, 1906, and No. 826,348, dated July 17, 1906, the regulator shown in the present application being of the same general construction as shown and described in my prior Patent No. 1,071,771, dated September 2, 1913. This regulator is shown in detail in Figs. 11 and 12. In these figures, 115 designates a rectangular frame set in an opening in one of the side walls of the furnace chamber and providing an opening between the furnace chamber and the external atmosphere. In this rectangular frame is arranged a swinging rectangular plate 116 fulcrumed at a point adjacent its lower end, as at 117, to the side members of the said frame 115. This fulcrum is located preferably at or close-ly adjacent the center of gravity of the plate, so that the said plate will remain stationary on its fulcrum at any point to which it may be moved. In order to insure the axis being through the center of gravitation of the plate 116 weight 118 is supported on the lower portion of the swinging plate, said weight being adjustably supported and held by upper and lower nuts 119 on threaded rods 120 secured to the lower portion of the said plate. The movement of the plate on its fulcrum is opposed by upper and lower tension springs 121, 122, the former being connected at its lower end to a projection 123 on the lower end of the swinging plate, and at its opposite end to an adjustable anchorage consisting of an eye or hook 124 on a threaded shank 124a extending slidably through a bracket 125 secured to the side frame 115, said threaded shank being adjustably held by means of upper and lower nuts 126, whereby the tension of the spring 121 may be adjusted. The lower spring 122 is also connected at its upper end to the said arm or projection 123, and its lower end is connected to a hook or eye 127 having a threaded shank 128 extending slidably through an opening in a bracket 12.9 on frame 115, said shank being adjustable relative to said bracket by means of nuts 130, whereby the tension on said lower spring may be regulated. These springs serve to oppose the swinging movement of the plate, and may be regulated to balance the action of any draft pressure in the furnace. The movements of the pressure regulator are employed to control the position of the stack damper 14 so as to control the rate of outflow of furnace gases through the stack.

In order to accomplish this result, I provide a pilot valve 131 having an inlet 132 connected by a pipe 133 with a source of fiuid under pressure, and a combined inlet and outlet 134 connected by a pipe 135 to the lower end of an operating cylinder 136 containing a piston 137 connected to a piston rod 138, which in turn is connected by a flexible connection 139 with a` lever arm 140 for operating the damper 14, said fiexible connection being passed over an intermediate guide pulley 141. The pilot valve is provided with a piston valve 142 connected loosely to a bracket arm 143 on the lower portion of the swinging plate 116. The pipe 133 is connected by a 'pipeI 144 to the upper end of the cylinder 136, above described. The pipe 133 contains hand valves 145, 146, on opposite sides of the connection with pipe 144, and the pipe 135 contains a hand valve 147. The pilot valve casing is provided with an. escape opening 148 at its lower end.

The operation of said pilot valve is to control the flow of fluid pressure to and from the lower end of the cylinder 136 in order to operate the piston 137 to control the damper 14. On the lever 140 is a weight 149 normally tending to hold the damper in open position. The construction of this pilot valve is specifically shown in F ig. 11, but I do notl deem it necessary to describe the same with greater detail, as it is of wellknown construction, and specifically does not form a part of my present invention.

The function of this regulator is to maintain a substantially constant pressure of furnace gases in the furnace chamber for the varying rates of air supply entering the furnace chamber for the purposes of combustion. In performing this function the regulator acts as follows: Should there be an increase of pressure in the furnace chamber above normal, the increase of pressure moves the plate 116 outwards, operating the pilot valve to control the fiow of motor fluid to the cylinder 136 to cause the damper 14 to be moved to increase the rate of outflow of gases through the stack, thereby reducing the pressure within the furnace chamber. If, on the other hand, there should be a decrease of furnace gas pressure below normal, the said plate 116 will be moved inwards (to the left in Fig. 12) by the external atmospheric pressure, which movement will operate the pilot valve to control the flow of fiuid under the piston to flow from the cylinder back through pipe 135 and out through the vent 148, thereby causing the damper 14 to be moved to reduce the area of the stack outlet, and thereby increase the pressure of gases within the furnace. IVhen the pressure is relieved under the piston 137, as just described, said piston is moved downwards by fluid pressure supplied to the upper end of the cylinder through the pipe 144, this pipe being in constant communication with the source of fluid pressure. The use of the balanced draft regulator 116 is an important feature of my present invention, as it maintains a constant draft pressure in the furnace chamber. Therefore, for any given area of air damper openings 55, 62, G3, there will be a given rate of flow of air through the damper opening 1?, whereas, if the furnace pressure varied, the amount of air which would pass through a given area of damper openings 55, 62, 63 would vary with the draft pressure in the furnace. As the area of air opening at 55, G2, 63 corresponds with the pressure of oil supplied to the burner, the dampers 60, 61 and 62 can be adjusted to be operated by the regulator 53 to give any desired rate of flow of air for the corresponding pressure of oil to the burner.

Applicant is aware that. it has been proposed to regulate the air supply damper, and the stack damper in accordance with the variations of the pressure of oil to the burner, but such construction will not accomplish the result of applicants invention, because it will not maintain a substantially uniform draft pressure in the furnace, due. to the fact that a given position of the flue damper in accordance with the oil pressure will not produce the same draft pressure in the furnace chamber for all conditions of running the furnace. For a given position of the flue damper, the draft pressure in the furnace chamber will vary with the draft of the chimney which varies with atmospheric conditions, and in plants where there are two or more furnaces connected to one chimney, the draft of the chimney is varied by the operation of the other furl naces, and the draft pressure in the furnace is also varied by the internal resistance of the furnace or boiler, due to accumulations of flue dust and ashes. In all of these conditions my invention maintains a substantially constant draft pressure in the furnace chamber for all rates of combustion.

The maintenance of a substantially uni form pressure in an oil burning furnace is vastly more important than it is in a coal burning furnace, because the resistance of an oil burning furnace is very low, practically zero, whereas, the resistance of a bed of fuel is very considerable. If 1/10th of an inch minus draft pressure. would supply the requisite amount of air for an oil burningl furnace or a fluid fuel burning furnace, and say 2 inches of draft pressure was necessary to supply air to an ordinary coal burning furnace, a variation of 1/10th of an inch in the draft pressure would double the variation in the air supply to the fluid fuel burning furnace, whereas, it would only vary the air supply to the coal burning furnace l /Qllth It is therefore apparent that a construction which provides a fixed position for the flue damper corresponding to any given pressure of oil to the burner will not maintain a substantially uniform pressure of furnace gases for varying rates of combustion, on account of thefluctuations in the draft of the chimney, due to atmospheric conditions, and due to variations in furnace conditions in other furnaces connected to the chim1'1ey,if any, and due to variations in resistance of the furnace and boiler on account of accumulations of soot and ashes which vary from day to day. rFliese variations in a fluid burning furnace amount to as much as the total draft pressure necessary for varying combustion. Instead of operating the damper 14 to control the rate of outflow of furnace gases, an equivalent would be to employ an induced draft fan connected to the stack and driven by an engine, the controlling valve of which would be regulated by the cylinder 13G.

In Fig. 3 I have shown another embodiment of the same broad invention, heretofore described, but instead of controlling the supply of air flowing into the furnace in accordance with the. pressure of oil fed to the burner, I effect such control in accorda-nce with the rate of flow oiI oil fed to the burner. In Fig. 3 I show the same structure as to the furnace proper as shown in Figs. 1 and Q, and also the saine construction of the means for maintaining a substantially constant pressure of furnace gases in the fire chamber, and therefore need not again describe these, as the previous description will be sufficient. In this form of the invention the burner or nozzle is shown at 16a, the same being supplied with steam under pressure through a pipe 20a, and by oil fed thereto by a pipe 52" supplied with oil under pressure from an oil pump 1T. The amount of flow of oil and atomizing steam may be controlled by a regulator 22 corresponding` to the regulator 2Q, and operating in the same manner as heretofore described. In this form of the invention, however, I provide means responsive to variations in the volume of flow to efi'ect the automatic operation of the dampers controlling the flow of air into the furnace, such regulator being shown generally at 53 in Fig. 3, and specifically in Figs. 4;, 5 and (3. As will be seen in Fig. 3, the regulator is interposed in the pipe 52a leading from the pump 172L to the burner or nozzle.

Referring' to Figs. 4, 5 and 6, the construction and operation of said regulator 53a will be described as follows :M150 designates a lower half or member. of a diaphragm chamber, the other half of which is shown at 151, said members being connected by headed bolts 152 and nuts thereon, said members clamping between a flexible diaphragm 153 shutting olf communication between said members, except as hereinafter described. Integral with the member 150 is an inlet connection 154 having a port 155 leading to an opening 156 through the flange of the member. 150 leading into a passage 157 in the wall of the member 151, said passage 157 communicating with the space in said member 151 above the diaphragm 153. The connection 154 is connected to that portion of the pipe 52"L nearest to and leading from the pump 17a. Connected to the lower member 150 is an outlet connection 158 (Fig. 5) opening into the lower chamber of the device below the diaphragm 153, said connection 158 being connected to that part of the pipe 52"L leading from said regulator to the burner 16a. The chamber in the upper member 151 above the diaphragm 153 opens through a port 159 into a valve casing 160, preferably formed integral with the member 151, and containing a tapered turn-plug valve 161, the latter having a port 162 adapted to communicate with the said port 159, and leading to the internal bore 163 of the valve, which in turn communicates with a passage 164 leading into the member 150 beneath the diaphragm 153. In order to provide for a tight lit, the valve 161 is preferably tapered and fitted to a correspondingly tapered bore in the casing 160 and is urged to its seat by a spring 165 surrounding a stem 166 on said valve, and at one end abutting a packing gland 167 threaded into the casing 160, and at its other end abutting the upper end oi the said valve 161. The valve is provided with a head 168 adapted to be engaged by a wrench or other suitable means by which it may be rotated. Connected to the diaphragm 153, in any suitable manner, as at 169, is one end 170 of a rod 171 extending upwards through a stuliing-box 172 in the upper wall of the member 151, the upper end of said rod 171 being pivotally connected, as at 173, to a lever 174, one end of which is pivoted as at 175 to the member 151, and the other end of which is connected to a flexible connection 176 passing upwards over a pulley 177, and thence downward to the levers 66 on the shafts 65 operating the dampers 60, 61, 62 in the same manner as described with reference to the form of invention shown in Figs. 1 and 2. The means for connecting the rod 171 to the diaphragm, consists of dished plate 170a having a ilange 170" secured by a fluid-tight joint to the lower face of the diaphragm by means of screws 17 0c extending through said flange, packing washers 170d between the flange and the diaphragm, and threaded into a washer or ring 170c on the upper side ol the diaphragm. The dished portion of the plate 170 extends upwards through a central opening in the diaphragm and has a central opening 170t through which the rod 171 extends, the rod having beneath said plate an enlargement or head 171a of greater diameter than the opening in said plate so that the rod and plate are connected. The under side of the plate is closed against leakage by a plate 171D held in place by the screws 170C. On the casing of the regulator is a bracket 17 8 between which and the lever 174 is suitably supported and held a compression spring 179 tending to move the lever,174 upwards. One end oi the sprin 179 is seated in a spring seat 180 supported on one end of an adjusting screw 181 threaded through the bracket 17 8, and by means of which the resistance of the spring 179 to downward movement of the lever 174 may be regulated. rlhe screw 181 may be locked in adjusted position by a jam nut 182 threaded thereon. Supported by the bracket 178 is a scale member 183 having a scale 184 calibrated to indicate gallons per minute or other iuiit of time of'flow oit fuel to the burner, the upper. edge of said lever 174 cooperating as a pointer with said scale. It will be understood that said scale may be calibrated to indicate any useful information measurable by position or movement of the diaphragm 153. The operation of this device is as follows The fluid fuel enters the connection 154 and flows through ports 155 and 157 into the space above the diaphragm 153, thence through the port 159 and valve ports 162, 163 and port 164 into the space beneath the diaphragm 153, from which space it 'flows outwards through the pipe 52"L to the burner 16a. The. valve 161 is operable tol cause a restriction to the flow between the upper and lower chambers of the regulator having 'the diaphragm between them, so as to create a reduction in pressure in the chamber beneath the diaphragm, this reduction in pressure being employed to cause movement of the diaphragm to operate the lever 174 to control the dampers. 1t will be understood that the valve 161 is set so as to result in a restriction giving the desired difference in pressure between the Huid in the two chambers, and that any variations of this difference of pressure, due to iiuctuations` in the rate of llow during the operation of the furnace, will operate the diaphragm to correspondingly regulate the position of the dampers 60, 61, 62. The chambers on opposite sides of the diaphragm 153 are pref- CTL ,rably designed so as to be of equal volume and synunetrical in shape so that the effect of the velocity head of the fluid flowing through them will not tend to move the diaphragm, any action of the velocity head on one side of the diaplufagm being counlerbalanced by a similar action on the other side. The result of the neutralizing or counterbalancing of the velocity head in the two chambers, is that the diaphragm. is actuated by the difference in total pressure due to the restriction in the passage between the two chanil'iers. 1t will thus be seen that when the steam pressure drops, the valve 22"l will be operated to increase the amount of fluid flowing from the pump 17 through the regulator 523 to the burner and that the greater the amount of oil flowing through the regulator, the greater will be the difference in pressure between the fluid above the diaphragm 153 and that below said diaphragm, resulting in the excess pressure above the diaphragm moving the rod 171 to swing the lever 171i to operate the dampers (S0, (il, 02 to increase the amount of air supply flowing into the furnace. 1f the boiler pressure increases, the opposite operation from that described takes place, that is, the regulator 22 operates to reduce the amount of fluid flowing through the regulator to the burner, which is followed by a reduction of the difference in pressure between the oil above the diaphragm 153, and below said diaphragm, permitting the diaphragm to move upwards, whereupon the spring 179 acting against the difference of pressure in the regulator moves the lever 17e upwards to control the dampers 60, 61, 62 to shut off or reduce the supply of air fed into the furnace.

lnasmuch as the balanced draftregulator acts in the same manner as described with reference to the form of the invention shown in Figs. 1 and 2, it is not necessary to repeat that description here. The valve 161 can be so adjusted that the variations in difference of pressure due to variations of volume of flow which cause the travel of the rod 171, can be made to give the dampers 60, G1 and 62 the desired position from minimum desired opening to maximum desired 'opening corresponding to minimum flow of fluid fuel to maximum flow of fluid fuel.

The regulator, as shown in Figs. 8, 1l, 5 and 6, is not claimed specifically herein, but is the subject of a divisional application for Letters Patent, filed by me on or about September 20, 1921, and bearing Serial No. 502,039.

The apparatus for regulating the area of the distribution of the air supplied to the furnace is the subject of a divisional application for Letters Patent, filed by me on or about October 6, 1921, Seral No. 505,804.

lVhat I claim and desire to secure by Letters Patent of the United States is 1. The method of operating a fluid fuel burning` furnace which consists in controlling the air entering the furnace in accordance with the rate of flow of fluid fuel supplied to the furnace, and controlling the outflow of gases to maintain a substantially constant pressure in the furnace chamber for varying` rates of air supply.

2. The method of operating a fluid fuel burning furnace which consists in controlling the air entering the furnace in accordance with the rate of flow of fluid fuel suppliei'l to the furnace, and controlling the outflow" of gases in accordance with varying rates of air supply to maintain a substantially constant pressure in the fr chamber for varying rates of air supply.

3. The method of operating a fluid fuelfired furnace which consists in controlling the area of the. distribution of air supplied to the furnace in a-ccordance with a characteristic of the flow of fluid fuel supplied lo the furnace.

1. r1`he method of operating a fluid fuelfired furnace which consists in controlling the area of the distribution of the air supplied to the furnace in accordance with the rate of flow of fluid fuel supplied to the furnace.

5. The method of operating a fluid fuelfired furnace which consists in controlling the area` of the distribution of air supplied to the furnace in accordance with a characteristic of the flow of fluid fuel supplied to the furnace, and producing a flame, the surface of which is directly proportional to the amount of fluid fuel supplied to the furnace.

(i. The method of operating a fluid fuelfired furnace which consists in automatically controlling the area of the distribution of air supplied to the furnace in accordance with a characteristic of the flow of fluid fuel supplied to the furnace, and producing a flame, the surface of which is directly proportional to the amount of fluid fuel supplied to the furnace.

7. The method of operating a fluid fuel burning furnace which consists in supplying fluid fuel and air for combustion to the furnace, and regulating the combustion in accordance with the rate of flow of fluid fuel fed to the furnace.

8. The method of operating a fluid fuel burning furnace which consists in supplying fluid fuel to the furnace chamber to be burned therein, supplying air to the furnace chamber for combustion, and regulating the supply of air in accordance with the rate of flow of fluid fuel fed to the furnace.

9. The method of operating a fluid fuel furnace, which consists in introducing air for combustion through a plurality of areas, and controlling the air supplied through the various areas in accordance with a characteristic of the flow of fluid fuel supplied to the furnace.

l0. The method of operating a fluid fuel 5 furnace, which consists in introducing air for combustion through a plurality of areas,

and controlling the air supplied through EMBURY MCLEAN.

the various areas in accordance with the rate of the flow of fluid fuel supplied to the furnace. 10

In testimony whereof I have hereunto signed my name.

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