US1833607A - Regulation of combustion of fuel in furnaces - Google Patents

Description

Nov. 24; 1931. B. GREENFIELD 1,833,607

REGULATION-OF COMBUSTION OF FUEL IN FURNACES FiledOCt. 2. 1922 3Sheets-Sheet 1 (I I I I II I90 \9? 7 i j zz um/W501 3& Qbtozmmg u M Nov. 24, 1931. B. GREENFIELD REGULATION OF COMBUSTION OF FUEL IN FURNACES Filed 06?.- 2. 1922 3 Sheets-Sheet 2 a h w mama NOV. 24, 1931. GREENHE'LD I 1,833,607

REGULATION OF COMBUSTION OF FUEL IN FURNACES Filed Oct- 2, 1922 3 Sheets-Sheet 5 I] Il ll IIIIIIII Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE BENJAMIN GREENEIELD, OF BARTLESVILLE, OKLAHOMA, ASSIGNOR TO DOHERTY BE- SEARCH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE REGULATION OF COMBUSTION OF FUEL IN FURNACES Application filed October 2, 1922. Serial No. 591,891.

This invention relates to the regulation of combustion of fuel in furnaces. More particularly the invention relates to a method of and apparatus for regulating the combustion of fluid fuels in steam boiler furnaces.

In my copending applications, Serial No. 365,366, filed March 12, 1920, for fluid fuel fired boilers; Serial No. 365,367, filed March 12,- 1920, for oil fired steam boilers;

1 and Serial No. 484,141, filed July 12, 1921,

for apparatus for controlling the combustion of oil in oil burners; different forms of apparatus have been described by WlllCh combustion of fluid fuel in a steam boiler furnace is automatically controlled by. varying the feed of fuel to the furnace 1n accordance with the steam boiler pressure and by varying the supply of air for combustion to the furnace substantially ina direct proportion as the fuel feed varies. This system vof combustion control is known in the trade and has the important characteristic that an oil fuel may be fed to the burner under a low pressure through a flow restricting mechanism, and the rate of feed may be varied from zero to a definite maximum without adjustment of the flow restricting mechanism.

The primary objects of the present invention are to provide an improved method of and apparatus for the aforementioned com bustion control system by which the fuel and power saving may be increased, the combustion control may be more effective and accurate, and by which an accurate record of the rate of combustion may be obtained.

Referring more particularly to the fuel and power saving, one feature of the invention contemplates the provision in. a combustion regulating apparatus having means for varying the oil feed in accordance with variations of the steam boiler pressure, of means for varying the volume of steam supplied to a burner in a direct proportion as the fuel feed varies. By this means the volume of steam for atomizing the oil would always correspond to the volume of oil to be burned, thus insuring the most efficient combustion, and the most economical use of steam.

\Vlien the combustion control system described in my aforementioned co-pending apboiler.

plications is used for operating a boiler at any rating between 25% and 100% of maximum rate of combustion, the exhaust flue gases will show a high substantially constant percentage of carbon dioxide and zero carbon monoxide content, which is an indication that the combustion is efiicient and complete, regardless of the variations of volume of fuel being burned. On the other hand, if the boiler is being operated at a low rating, for example, at or less than 25% of the maximum rate of combustion, the percentage of carbon dioxide in the flue gas has a tendency to fall, due to mechanical limitations in the operation of the regulating apparatus and to the leakage of the draft damper.

Accordingly, another feature of the invention contemplates the provision in a combustion regulating apparatus having means for varying the fuel feed in accordance with the demand for heat, and for varying the air for combustion in direct proportion to the variation in the fuel feed, of means for compensating for mechanical limitations of the apparatus for different rates of firing.

The feed of oil to a furnace burner according to the combustion control system described in my aforementioned co-pending applications consists in maintaining the oil in a level chamber and forcing the oil from the chamber to the burner through a circuit having a flow restricting orifice, by developing a gas pressure on the oil in the chamber. If the oil level in the chamber isnot maintained constant, the volume of oil being fed to the burner will not be strictly accurate or in accordance with the fuel demand of the In a boiler furnace using a large amount of'oil, and particularly where the steam demand varies widely, inaccuracies in the oil feed may seriously impair the combustion efiiciency.

With this in View, another feature of the invention contemplates the provision in an oil feed system having aconstant level oil feed chamber, with a conduit leading to an oil burner, of means for maintaining a constant level of oil in the chamber.

In the combustion control system described in my aforementioned co-pending applications, a low pressure usually of not more than.20 inches of water is employed for forcing oil from a level chamber to the burner, and this same pressure is used for operat-. ing a motor to control the draft damper. This low pressure is adapted for operating only certain kinds of motors, and it is "desirable in many cases to use a comparatively high pressure for securing an accurate operation with a smaller damper motor.

Accordingly, another feature of the invention contemplates the provision in a'combustion regulating apparatus having an oil burner connected with a level chamber, and a motor operated damper, of means for developing a comparatively high motor operating pressure, which varies in accordance with the heat demand and developing alower pressure directly proportional to the motor operating pressure for forcing oil from the level chamber to the burner.

Another feature of the invention consists in theprovision in an automaticcombustion regulating system, of a meter for giving a plant rate of combustion record, and a. record of the rating of each boiler in a plant.

With these and other objects and features in view,the invention consists in the improved method of an apparatus for controlling furnace combustion hereinafter described and specifically defined in the accompanying claims.

The various features'of the invention are illustrated in-the accompanying drawings, in which: a

Fig. l is a diagrammatic view in front elevation with parts shown in section of a battery of boilers provided with a combustion regulating apparatus embodying the preferred form of the invention;

Fig. 2' is a view in elevation partly in section of the rate of the combustion meter;

Fig. 3 is a vertical sectional view of one of the valves used for controlling the flow of steam to the oil burners;

Fig. 4 is a vertical sectional view of another valve used in controlling the flow of steam to the oilburners;

Fig. 5 is a vertical sectional view of an overflow tank by which oil may be returned from the level chamber to the oil supply with out danger of the conduits becoming airbound;

Fig. 6 is a view in side elevation of a variable radius sheave wheel used for operating the draft damper;

Fig. 7 is a vertical sectional view of the sheave wheel shown on the line 77 of Fig. 6

n Fig. 8 is a top plan view of the sheave wheel shown in Fig. 6; and

Fig. 9 is a detail sectional view of avalve for varyingthe oil feeding pressure.

The present, invention is particularly adapted for controlling the combustion in a batteryof boilers. In the drawings are shown two of a well-known type of water tube boilers having furnaces 10 provided with oil burners 12, the air for combustion of the oil being admitted to the furnace through inspection doors 14or the ventilation doors16. The door openings 14 and 16 for the admission of air are not ordinarily adjusted or controlled, but the control of air through the furnace is obtained by means of dampers 18 which are located in the outlet flues or stacks 20.

The oil which is supplied to the burners 12 is taken from a storage tank 22, Fig. 1, by means of a pump 24 and forced through conduits 26, 28 and 30 to an oil feed regulator generally indicated at 32. That part of the conduit indicated at 28 is preferably a preheater. The proper control of the flow of oil from the oil feed regulator to the burners depends upon a constant level or head of oil in the regulator 32 and to that end the regulator is provided with a chamber 34, shown as of annular form, to which oil is delivered by the pump. The inner wall of the chamber 34 constitutes a Wier 38. The pump 24 supplies oil to the chamber at a faster rate than it is withdrawn therefrom for burning, the excess oil spilling over the wier into a second chamber or compartment 36 with which the regulator is provided. For convenience of description chamber 34 may be termed a constant level chamber and the chamber 36 an overflow chamber or compartment. Oil received in the overflow chamber flows back to the storage tank through suitable connections. These connections preferably include a restriction 40, through which oil flows rela tively slowly in order that a body of oil may be maintained in the overflow chamber for a purpose which will presently appear, and a trap 44. A pipe 42 connects the restriction and trap and a pipe 48 connects the trap with the storage tank at any suitable point 50. The oil outlet from the trap is controlled byavalve 46 at the top of pipe 48 and this valve is in turn controlled by afloat 52. lVhen the oil in the trap falls to a predetermined level the float closes the valve in order to prevent air from entering the discharge pipe 48. The trap is open to the atmosphere through a suitable vent 54.

The flow of oil into the constant level chamber 34 is controlled by a float in the overflow chamber 36 and for this purpose the feed pipe leading to the chamber 34 is provided with valve 56 which is connectedby suitable linkage 58 and 60 with a float 62 in the overflow chamber 36. The rate of discharge from the restriction 40 is such that oil must continually pass over the wier 38 in order to maintain a given body of oil in the overflow chamber. By maintaining the chamber 34 always full of oil to overflowing a constant head of oil is assured under all conditions of operation and any irregularities in the feeding of the oil to the burners due to'variations in oil head in the chamber are avoided. 7

Oil for combustion in the burners 12 flows from a point near the bottom of the level chamber 34 through a pipe or pipes 63 into as many individual feed vessels or chambers 64 as there are burners 12 and flows from said vessels to the burners through individual pipes 66. The pipes 63 leading from the level chamber 34 to said vessels are provided with orifices 68 which are preferably located at the oil outlet ends of the pipes. The outlet ends of the pipes 63,that is to say, the orifices 68 as shown in the drawings,are disposed preferably in the same horizontal plane or level as the top of the wier 38. The slightest pressure on the oil in the level chamber '34 will therefore cause a flow of oil through the pipes 63 into the vessels 64. On the other hand as soon as the pressure on the oil in chamber 34 ceases, the flow of oil to the vessel will immediately cease. Extending upwardly from the vessel 64 is a riser pipe 70 which is open to the atmosphere. Depending on the rate of supply to the vessel the oil will rise in the pipe 70 until'the head thereof equals the pressure exerted on the oil in the level chamber 34. The hydrostatic head on the burner 12 is therefore under the direct control ofthe pressure exerted on the oil in the level chamber.

It is desirable that suflicient oil be maintained in the vessel 64 to prevent air from which is controlled by a float 74 within the vessel. If the level of the oil in the vessel 64 falls below a predetermined point, the float 74 will close the valve to trap the pipe 66 full of oil. By this means the pipe 66 will always be maintained fullof oil and no air will be drawn into the burners through the pipe 66 so that either gravity or suction feed type of burners may be used in the furnaces 10.

It will be readily appreciated that the pipe 66, the vessel 64 and the riser pipe 70 constitute in effect an oil-stand-pipe from the foot of which oil flows to the burner 12 and that the head of oil in the stand pi e depends on the rate of feed from the oil eed regulator 32, the rate of feed in turn depending on the boiler pressure. By increasing the head of oil in the stand-pipe as the boiler pressure falls, a greater volume of oil will of course be supplied to the burner as will be readily understood. p

The volume of oil which will be .supplled to the burners through the orifices 68 will depend upon the pressure on the body of 011 within the level chamber 34. This pressure is referably held as low as practicable, in

or er that any type of fuel may be used and still insure a desired and dependable rate of firing. By the use of low feed pressures, comparativelv large orifices 68 may be used, and therefore low grade of oil which may contain dirt or sediment may be used without danger of the orifice becoming clogged. According to the equation in which Q, represents the volume or rate of flow, a, the area of the orifice, g, the gravity coeificient, h, the loss in head across the orifice, and C the discharge coeflicient based upon the shape of the orifice, it will be understood that the rate of flow of oil through the orifices 68 will vary in accordance with the square root of the pressure maintained within the level chamber 32.

In mycopending application, Serial No. 484,141, filed July 12, 1921, I have set forth in detail the principle of operation of a damper motor by the fuel feeding pressure, and have shown that the rate of feed of oil varies approximately in a direct proportion as the rate of flow of air through the boiler varies. Also, I have shown that the rate of flow of air varies substantially in a direct proportion as the area of the stack damper opening varies. The area of the stack damper opening may. be varied by adjusting the dampers 18 with motors which are operated by a pressure equal to or proportional to the fuel feeding pressure. In the present invention the damper motors are preferably operated by pressures, which are proportioned to the oil feeding pressures, but which are much higher than the oil feeding pressure in order to insure a positive and accurate adjust-mentof the dampers with a minimum size of damper motor. To accomplish this the dampers 18 are fixed to shafts 76 which are preferably mounted on bearings so as to rotate with a minimum friction. The shafts are rotated to adjust the position of the dampers in the stack by means of a motor which consists of a cylinder 78 attached to the side of the furnace and a piston 80 which is connected by means of a cable 82 with the sheave wheel 84 on the outer end of the shaft 76. The end of the shaft 76 opposite the sheave Wheel, is turned to an angle of 909with the axis of the shaft in order to form a pendulum arm 86 and a series of weights 88 and 90 are mounted respectively on the pendulum arm 86 and piston 80, in such a manner as to maintain the dampers 18 and shafts 76 in balanced position. W'ith the dampers held in balanced position a comparatively slight pressure acting under the piston 80 wi I act to adjust the position of the damper,

and it will be apparent that by adding more weights to the piston and pendulum arm, the amount of pressure required for adjusting the dampers may be varied. Expressed in another way, by adding to or taking weights from the pendulum and piston, the extent of the movement of the damper, for different pressures operating on the motor pistons, may

e varied.

The damper motors are operatedby a pressure which is developed empirically to provide for the size of the damper, the kind of motor and the condition under which the boiler is being fired. Although this pressure is empirically developed, the pressure when once established is varied or controlled in accordance with the steam demand of the boiler or the boiler steam pressure. .Further, the

motor operating pressure is controlled between fixed maximum limits and minimum limits.

To develop the pressure for operating the damper motors, live-steam from the boiler is taken from a header 91, which is preferably common to all of the boilers, and passed through a pipe 92, astrainer 94, and from thence through a steam pressure regulating and reducing valve 96 to a nozzle 98. The nozzle 98 is a steam aspirating nozzle which passes'the steam through a throat 100 and acts to draw in air through an opening 102. The mixture of steam and air passes into a pipe104 and the pressure of this steam and air is imparted through pipes 106 connected to the bottom of cylinders 78 to act upon the pistons 80. The steam pressure at the aspirating nozzle 98 is substantially constant so that the rate of flow of steam through the nozzle is substantially constant. To control the pressure developed by the aspirating nozzle, whereby the dampers may be operated in accordance with the steam demand on the boilers, the gas and air mixture passes from the pipe 104 into a pipe 108, which is provided with a relief valve 110 arranged to release the pressure on the pipe 108 when it reaches a predetermined maximum. To control the minimum pressure and the variation of pressure from minimum to maximum, a throttle and relief valve 112 is mounted in a pipe 114 connected to the pipe 108, and this valve is operated by means of a regulating diaphragm 116 which communicates through a pipe 118 with steam header 91. By this arrangement the valve 112 is under the direct control of the active boiler steam pressure and varies the pressure in the pipe 108 in accordance with the variations of the boiler steam pressure. Thus the pressure in the lines 104 and 106 is varied between the maximum pressure and atmospheric pressure specifically in accordance with the variations of the boiler steam pressure; A considerable portion of the steam used in generating the pressure in the lines 104, 106 and 108 will condense in these lines and therefore the. lines should preferably be set on a grade so that the condensed steam will drain toward the pipe 104. A trap 120 is connected with the lowest portion of the line 104 by which the condensed steam may be withdrawn from the lines. By the use of the inspirating nozzle 100 having air opening 102 it is possible to maintain the pressure on the lines 104, 106, and 108, with a minimum volume of steam,

steam and an excess of condensed steam.

and-thereby avoid the use of anexcess of Since a mixture of steam and air at a given pressure has a much lower temperature than saturated steam at the same pressure it follows that the temperature of the motive pres-' sure lines 104, 106, 108, 140, 148, and 160 will be comparatively lowand hence condensation losses will be at a minimum. Also all parts of the piping which are dead ends and I such chambers as 32, 78, etc. will soon become air bound-and hence carry a temperature only a little above room temperatures, thus still further reducing condensing of motive steam.

It is not desirable that the stack damper 18 should be made to fit closelyin stack 20,

ent invention the existence of a considerable area of leakage between the damper and the stack causes the ratios of rate of furnace ventilation and the rate of flow of oil to the burner to approach each other more closely than if there were no leakage. For exam le, if the leakage area around the damper w en in closed position is 25% of the transverse area of the stack, and the installation is set to attain maximum combustion capacity at a pressure of 18 inches of water in constant level chamber 32', the ventilation of the furnace would be theoretically correct at 33% of the combustion capacity, and a pressure of two inches of water, and also at full combustion capacity. Between 33% and 100% of the combustion capacity, if only the area of the oil feed orifice, the head of oil across the orifice and the area of the opening defined by the stack damper are considered, the combustion' in the furnace would be theoretically in a condition of slight under-ventilation. Ithas been found, however, by experience that the boiler under such conditions is actually slightly over-ventilated, due it is thought to the effect of the increasing flue gas temperature with increased rates of combustion, and also to the fact that the law of flow of gases past the stack damper is not actually the same as the law governing the flow of fluid through an orifice in a thin plate.

It has been determined in a number of commercial installations that by the use of the present invention the ventilation of a burner may be accurately pro ortioned to the rate of the feed of oil to the Burner as evidenced by a constant'percentage of CO in the exhaust gases between combustion rates of 25% and 100%. It is not ordinarily of commercial importance to regulate the ventilation of an oil burner in strict accordance with the rate of flow of oil to the burner at rates of com bustion less than 25% of the maximum rate of firing.

In order to obtain an accurate proportioning of'the air supply to the fuel supply at rates of combustion below 25% of the maximum, and, in fact, for all practicable rates of combustion, and, further, to provide for the deficiencies of mechanical construction, the sheave wheel 84 is provided with an adjustable peripheral surface by which the movement of the damper relative to the movement .of the damper motor may be varied and controlled to obtain any desired regulation of the flow of air through the boiler furnace.

The variable. radius sheave wheel 84 is shown in detail in: Figures 6, 7 and 8. This sheave wheel consists of a segment 122 keyed to the damper shaft 76. The cable 82 by which the sheave wheel is connected with the piston 80 of the damper motor passes through a groove 124 in peripheral face of the sheave wheel and is secured in a block 126 at the upper end of the segment. The movement which may be imparted to the damper 18 through the sheave wheel may banned by varying contour of the peripheral surface of the groove 124. To accomplish this a series of clamping screws 128 are mounted on slots 130 positioned in the peri heral surface of the segment, the slots 130 eing arranged in a radial position to permit the screws to be clamped at various radial distances fromthe axis. The screws 128 may be held against movement toward the axis of the sheave wheel by means of set screws 132, there being one set screw for each slot 130, the set screw passing through the rim of the segment and into the path of movement of the clamping screws 128.

To assist in obtaining a balanced condition of the damper 18- when the damper is used in a horizontal flue or duct a series of threaded openings 134 are formed in the hub of the segment 122, which are arranged to receive a rod 136 that is provided with an adjustable weight 138. By this construction it will be seen that the movement of the sheave wheel by the movement of the motor piston can be accurately controlled. and varied in order to give any desired movement to the damper 18 relative to the movement of the motor operating piston and the pendulum 86. If for any reason the apparatus does not operate in accordance with the theoretical and commercial requirements, the adjustable sheave wheel 84 may be utilized for obtainv ir the desired characteristics.

shown in the drawings preferably would be from about 0 to 15 pounds per square inch.

These pressures however are too high for use in feeding oil to the burners because the use of a high pressure necessitates the use of a comparatively small orifice, and a small orifice gives trouble, due to clogging when using duty or the lower grades of oil. It is preferred therefore that pressures lower than the motor operating pressure, but directly proportional to the motor operating pressure, may be used for feeding the oil in order to maintain the proportional relation between the rate of the feed of the oil and the rate of the flow of air through the furnace. To accomplish this the pressure in the line 108 is imparted to the oil in thelevel chamber 34 through a direct proportioning device. This device consists of a pipe 140, Fig. 1, connected with the pipe 108, a fixed orifice 142 in pipe 140, an adjustable orifice 144 in apipe 146,

and a pipe 148 connected between the, pipe 146 and the regulator 32. The adjustable orifice 144 consists of a valve 150, see Fig. 9, wh ch may be manually adjusted to give any des red opening and in order to develop the cleslred pressures in the regulator 32. The valve 150 consists of a casing 152 havin a plug 154 rotatably mounted therein. The plug 154 has a triangular opening 156 which 1s arranged to cooperate with a V shaped slot 158 in the casing 152 to provide a square orifice opening of varying size as the plug is rotated in the casing.

In accordance with the well known formula the approximate rate of flow of fluid through an orifice is Q K 29h- Since the volume of gas which passes through the orifice 142 is the same as the volume of gas which passes through the orifice 144, the

quantity of gas passing through the orifice 144 would be equal to with Q being the same in both cases. Therefore Since the constant K is unaffected, and the constant K is fixed by empirical adjustments in obtaining the desired pressure, it is apparent that the pressure h is always directly proportional to the pressure 71., and therefore the pressure at inlet side of the orifice 142 is proportional to the pressure at the outlet side of the orifice 142. This proportional arrange ment is particularly advantageous in that a fixed orifice 68 maybe used in the feed chambers, and the rate of feeding of the oil may be varied by adjusting the orifice 144 or valve- 150. Regardless of the adjustment of this valve, a proportional regulation will be maintained between the oil feed pressure and the damper operating pressure. To prevent an excess pressure being placed on the oil feed, a tube 160 is connected to the pipe 146 and arranged to di in a water seal 162 whereby the pressure which may be developed in the oil level chamber will be limited to the depth of submergence of the tube 160.

- the volume of steam being supplied to the oil burners. To this end the steam passing through the pressure regulating valve 96, Fig.

.1, flows through a pipe 164 to a regulating valve 166, which controls the volume of the steam flowing to the oil burners between cer-' tain minimum and maximum limits. The regulating valve 166 is shown more particularly in Fig. 4. This valve-consists of a single poppet valve which is operated by means of a diaphragm 168 positioned within a casing 170. The diaphragm 168 and the poppet are normally held in open position by means of a spring 172 mounted between a stem 174 engaging a plate upon the diaphragm and a yoke 176 integral with the casing 170. To control the operation of the valve 166 through the diaphragm 168 in order to insure that the flow of steam shall be proportional to the flow of the oil to the burners, a pressure is applied to the upper side of the diaphragm through a pipe 178 which is proportional to the pressure in the damper motor pressure line 104. To this end an orifice disk 180 is mounted in a pipe 182 connected with the pipe 164 and arranged to obtain the full steam pressure in pipe 164. The steam passing through the orifice in disk 180 flows througha pipe 182 and then through a valve 184 which is operated by a diaphragm 186 under control'of the pressure in the line 104.

The valve 184 is shown more particularly in Fig. 3. This valve consists of a double poppet valve which is normally held in open position by means of a compression spring. 190 mounted between the diaphragm 186 and a diaphragm casing 192. The upper portion of the diaphragm casing 192 is connected by means of a pipe 194 to the pressure pipe 404' so that the pressure on the upper side of the diaphragm 186 is the same as the pressure in the pipe.104, or the same as adamper motor operating pressure. By means of the orifice 180 a pressure may be obtained in the operate to reduce the steam flow to the burner to zero whenthe oil flow is discontinued because better results are obtained if a sufficient quantity of steam is permitted to flow to completely atomize the oil when it starts to flow in small quantities. Therefore the setting of the spring 172 is such that when the oil feeding pressure is so reduced that there IS no oil feed, a small quantity of 'steam will continue to pass to the burner. Accordingly, the rate of steam supply is directly proportional to the rate of oil feed only at rates of steam flow above the minimum as determined by the setting of the valve 166. Further, the maximum steam flow to the burners will be determined by the setting of the pressure regulating valve 96.

The steam passing through the regulating valve 166 flows through a line 196 and lines 198 to the burners 12. Valves 200 are provided in the lines 198 by which steam may be cut off if it is desiredto discontinue the use of a burner, and by means of which the flow of steam to the individual burners may be equalized.

The rate of combustion in the boiler furnace depends upon the rate of fuel supply and the rate of air supply. In the present invention both the rate of fuel supply and the rate of air supply are controlled and coordinated.

Further, the control of the air and fuel su ply depends upon the steam pressure or t e steam demand on the boiler. Therefore, the air controlling pressure or the fuel feeding pressure is a function of the boiler rate of combustion and can be used in making a record of the'boiler rate of combustion. The boiler rate of combustion may berecorded by a recording meter which is connected to any one of thepipe lines 104, 106, 108, or 148.

'As shown in Fig. 1 the rate of combustion meter is connected to the pipe 104. This com-. bustion meter is shown more particularly in Fig. 2, and consists-of a motor 202, which is connected topip'e 104, to be operated by the pressure in the pipe and a recording mechanism 204 connected with the motor by means of a cable 206. The motor 202 consists of a cylinder 208 in which is mounted a cup 210.

The bottom of the cup 210 is closed and is connected with'the cable 206. A cylindrical lib ' upon the lower surface of the cup and diaphragm 212. The diaphragm212 is comparatively long or cylindrical and the walls on which it rolls are parallel. Therefore during the movement of the cup 210 relative to the cylinder the effective area of the bottom of the cup and cylindrical diaphragm will not be changed. The cable 206 passes through a cover 214 mounted on the top of the cylinder 208, and is connected to a disk 216 rotatably mounted in the recorder casing 204. A pendulum 218 is pivotally connected to the disk 216 and a series of weights 220 are mounted on the pendulum which are accurately proportioned to weights 222 mounted within the cup 210 of the motor 202. By means of weights 220 and 222 the cup 210 may be adjusted to come to a position of equilibrium such as shown in Fig.2 at the time the pressure within the motor 202 falls below a predetermined point. The movement of the cup 210 of the motor 202 under the influence of oil feeding or motor operating pressure is imparted to a recording pen 224 by means of a link 226. The link 226 carries a roll 228 which is normally held in contact with the pendulum 218 by means of a spring 230 connected between the pen arm 224 and the re-.

cording casing'204. The end of the link 226 adjacent to the roll 228 is pivoted to a distance lever 232 which is pivotallymounted to the casing 204. A pivoted joint is provided in pen arm at 234 in order to vary the zero position of the pen upon a chart 236 which is normally held below the pen arm on a dial arranged to be operated by means of the usual clock mechanism, not shown. By varying the amount of weights 220 and222 which are placed respectively on the pendulum 218 and the cup 210 the extent of the movement of the cup due to predetermined pressures on the line 104 may be varied. By this means the extent of movement of the motor 202 can be adjusted to accurately hold the pen within the calibrations of the recording chart, and no matter what pressure range is used the meter may be adjusted to give full pen travel.

The rate of combustion is the best record which may be obtained for boiler furnace economy, and by the rate of the combustion recording mechanism described above a chart may be provided which will give the percentage of boiler rating of each boiler of a battery and also a plant rate of combustion record. If the motor operating pressure is a higher pressure than it is desirable to use for making the boiler rating record, a proportioning device similar to the proportion ing device for providing the pressure of the oil feeding chamber from the line 108 may be used between the motor 202 and the line 104.

The chart on this meter may be calibrated to read in terms of percent plant or boiler normal rating, percent of maximum rate of combustion on the plant and hence individual boilers, or it may be calibrated to read the pressure in the line to which it is connected. Because of the adjustable feature of the meter itself a few stock sizes of meter charts can be made to take care of any number of conditions.

As shown in the drawings, the combustion controlling mechanism of the present invention is intended to be used in conjunction with a battery of boilers. One constant level oil feed chamber may supply the burners of two or more boiler furnaces, and if convenient one damper motor may operate more than one damper.

In developing empirically the pressure for feeding fuel to the burner and the pressure for controlling the air supply a steam injector has been used which places a mixture of steam and air on the motive pressure pipes. It is obvious that this motive pressure may be de- .veloped by steam alone or by gas alone. Therefore, throughout the specification and claims where reference is made to the motive pressure, it is to be understood that this pressure may be a gas pressure, a vapor pressure or a pressure due to a mixture of gas and vapor.

The combustion controlling system in the present invention controls the volume of oil, the volume of steam and the volume of air flowing to the furnace in a unit of time, or in other words, the system controls the rate of flow of steam, oil and air to the furnace. In the claims reference is made to the volume of fluid fuel, the volume of steam, and the volume of air, and it is intended by these terms to include the rate of flow of fluid fuel, the rate of flow of air, and the rate of flow of steam.

The preferred form of the invention having been thus described, what is claimed as new is 1. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, a damper for controlling the flow of air througlrthe furnace, means for supplying oil to the burner comprising a regulator having an oil feed compartment and an overflow compartment separated by a weir, connections between the oil feed compartment and the burner having a flow restricting device therein, an oil feed storage, means for supplying oil from storage to the feed compartment at a rate faster than oil is fed to the burner, means for returning oil from the overflow compartment to storage, means controlled by the flow of oil from the overflow compartment to storage to maintain a substantially uniform head of oil over the weir, and means to force oil from the feed compartment to the burner.

2. In a fluid fuel fired boiler, the combinameans to force oil from the chamber to the burner.

3. In a fluid fuel fired boiler, the combination of a furnace, an oil burner for the furnace, means for controlling the flow of air through the furnace, means for supplying oil to the burner comprising a constant level chamber, a vessel having a vented riser con-- nected therewith, connections between the vessel and the level chamber having a flow controlling orifice therein, a conduit between the vessel and the burner, a valve in the conduit controlled by afloat in the vessel, means for supplying oil to the level chamber, mechanism for maintaining substantially constant head of oil in the level chamber, and means to force oil from the level chamber to the burner.

, 4;. In a fluid fuel fired boiler, the combination of a furnace, an oil burner for the furnace, means for controlling the flow of air through the furnace, means for supplying oil to the burner comprising a regulator having a constant level chamber and an overflow compartment separated by a weir, connections between the chamber and the burner having a flow restricting device therein, an oil storage, a pump connection between the oil storage and said chamber, a valve in said connection, a float in the overflow compartment for operating the valve, a conduit between the overflow compartment and the storage having a flow restricting device therein, and means to force oil from the regulator to the burner.

5 In a fluid fuel fired boiler, the combination of a furnace, an oil burner for the furnace, means for controlling the flow of air through the furnace, means for supplying oil to the burner comprising a regulator having a constant level chamber and an overflow compartment separated by a weir, connections between the chamber and the burner having a flow restricting device therein, an oil storage, a pump connection between the oil storage and the chamber, a valve in said connection, aconnection for leading oil from the overflow compartment back to storage, and means for controlling said valve to maintain a substantially uniform rate of flow of oil from the overflow compartment to stor- 6. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, a damper for controlling the flow of air through the furnace, and means for supplying oil to the burner comprising a constant level chamber, connections between the chamber and the burner, an oil storage, a pump connected between the storage and the chamber, a conduit leadingfrom the chamber to storage having a float chamber therein, a float positioned in the chamber, and a valve in the conduit connected with the float and arranged to maintain the conduit full of oil.

7. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, means for controlling the flow of air through. the furnace, means for supplying oil to the burner comprising a regulator having a constant level chamber and an overflow compartment separated by a weir, connections between the chamber and the burner having a flow restricting device therein, an oil storage, a pump connection between the storage and the chamber, a valve in the said connection, a float in the overflow compartment for operating the valve, a trap chamber, a conduit connected between the overflow compartment and the trap chamber having a flow restricting device therein, a pipe connected between the trap chamber and storage, and a valve in said pipe having an operating float mounted in the trap chamber.

8. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, means for controlling the flow of air through the furnace, means for supplying oil to the burner comprising a constant level chamber,

connections between the chamber and the burner, a flow restricting device in the connections, means for supplying oil to the chamber, a pressure developing mechanism, a regulator for said mechanism connected with the boiler and arranged to regulate the pressure developed in accordance with the boiler steam pressure, and a device connecting the pressure mechanism with the chamber arranged to maintain a pressure in the chamber proportional to but lower than the pressure created by the mechanism.

9. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, a damper for controlling the flow of air through the furnace. and means for supplying oil to the burner comprising a constant level chamber, connections between the chamber and the burner, a flow restricting device in the connections, means for supplying oil to the chamber, a pressure developing mechanism, a regulator for the mechanism connected with the boiler and arranged to regulate the pressure in accordance with the boiler steam pressure, a device connecting the pressure mechanism with the chamber arranged to maintain a pressure in the chamber proportional to but lower than the pressure created by the mechanism, a motor for operating the furnace damper, and means for applying the pressure developed by said mechanism to the motor.

10. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, a damper for controlling the flow of air through the furnace, and means for supplying oil to the burner comprising a constant level chamber, connections between the chamber and the burner, means for supplying oil to the chamber, a pressure developing mechanism, a regulator for the mechanism connected with the boiler and arranged to regulate the pressure in accordance with the boiler steam pressure, a conduit connected between the pressure developing mechanism having a fixed and an adjustable orifice therein, and a pipe connected between the chamber and the portion of the conduit between the two orifices. v

11. In a fluid fuel fired boiler, the combination of a furnace, a burner for the furnace, a damper for controlling the flow of air through the furnace, an oil feed chamber, an oil storage, means for delivering oil from the storage to the feed chamber, connections between the chamber and the burner having a flow restricting orifice therein, a pressure developing mechanism, a regulator for the mechanism connected with the boiler and arranged to vary the pressure in accordance with the boiler steam pressure, a conduit connected with the pressure mechanism and the chamber, a fixed orifice in the conduit, an adjustable orifice in the conduit, and a pipe connected between the chamber and the portion of the conduit between the orifices.

12. In a fuel-oil feeding device for a boiler furnace, the combination with a burner through which fuel is supplied to the furnace for generating steam, of an oil stand pipe extending upwardly from the burner, means for maintainin a head of oil in said standpipe over said fiurner and means for increasing the head of oil in the standipe in proportional relation with the fall 0 steam pressure ,in the boiler, said means including a chamber containing oil under a constant head, a conduit leading from said chamber to the stand-pipe, the outlet end of said conduit being in substantially the same horizontal plane as the upper oil level in said chamber, and means for exerting a boiler-pressurecontrolled pressure on the oil in said chamber to cause the oil to flow to the stand-pipe.

13. In a fuel-oil feeding device for a boiler furnace, the combination of an oil standpipe', a burner supplied with oil from the foot of the stand-pi means for cutting off the flow of oil to t 0 burner when the head of oil in the stand-pipe falls to a predetermined point, and means for increasing the head of oil in the stand-pipe in proportional relation with the fall of steam pressure in the boiler.

14. In a system of regulation for liquid fuel burning boiler furnaces, means for feed- ,ing liquid uel to a plurality of burners including a plurality of duplicate fuel feeding orifices of constant area, one orifice for each burner, a constant level fuel supply chamber with which said orifices are in open communication, means for developing a motive pressure in the fuel supply chamber varying in inverse proportional relation with variations in'the boiler pressure to feed fuel through said orifices, and conduits for supplying the burners with the fuel which has passed through the orifices.

In testimony whereof I afiix my signature.

BENJAMIN GREENFIELD.

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