US2212606A - Combustion control - Google Patents

Description

Aug. 27, 19 0- J. J. KLINKER COMBUSTION CONTROL Filed March 18, 1937 s Sheets-Sheet 1 27, 1940- J. J. KLINKER 2,212,606

COMBUSTION CONTROL Filed lla'rch 18, 19:57 3 Sheets-Sheet 2 JOHN J. KLmKE/a.

Aug. 27,1940. J. J. KLINKER COMBUSTION CONTROL Filed March 18, 1937 3 Sheets-Sheet 3 Patented Aug. 27, 1940 PATENT OFFICE COMBUSTION CONTROL John J. Klinke'r, Decatur, Ill., assignor to A. W. Cash Company, Decatur, 111., a, corporation of Delaware Application March 18, 1937, Serial No. 131,678 4 Claims. (Cl. 158-119) This invention relates to combustion control, and more particularly to the control of the combustionof fluent fuels, such as gas or oil.

It is ordinarily desirable in the burning of such fuels to maintain a predetermined ratio between the rate atwhich fuel is supplied and therate at which air is supplied to support the combustion of the fuel. Furthermore it is also desirable to provide means whereby this ratio can be adjusted to compensate for changes in operating conditions. For example, if a change takes place in the heating value of the fuel, it will usually be necessary to make an adjustment in the fuelair ratio .in order to maintain proper combus- 35 tion. This problem has been recognized, and various solutions have been proposed, but it has been considered necessary heretofore to employ complicated mechanisms, such as adjustable lever fulcrums, which are not only expensive but 0 also likely to reduce the sensitivity of the control system.

It is accordingly one object of the invention to provide a simple and reliable apparatus for supplying fuel and air to a furnace in a predetermined ratio and for varying the ratio as may be desirable.

It is a further object of the invention to provide a simple and reliable apparatus for controlling the rate of supply of fuel and air to a furnace in accordance with the demand for heat, for

maintaining a predetermined ratio between the quantities of fuel and air supplied, and for varying the ratio as may be desirable.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with my invention in its preferred form, I utilize a fluent fuel and air as the elements of combustion, and 1 supply at least one of these elements to a furnace burner at a pressure above atmospheric and allow a small stream thereof to escape from a zone immediately anterior to the burner. A control force is provided which is a function of the rate of flow of the escaping stream, and this is balanced against a second control force which is a function of the rate of supply of the other element of combus-.

tion. The rate of supply of one element of combustion is regulated in such a way as to maintain a balance between these forces. Preferably the supply of fuel is controlled in accordance with the demand for heat, and the supply of air is controlled to maintain the two control forces balanced. By varying the rate of flow in the escaping stream, I am able to'control the ratio between the fuel and air supplies in a very simple and effective manner.

Referring to the drawings illustrating one em- 5 bodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is an elevation of a steam boiler furnace and a combustion control system therefor, with certain parts shown in section; 10

Fig. 2 is an enlarged view of certain parts of the apparatus, partially broken away for, clearness of illustration;

Fig. 3 is a view similar to Fig. 1, showing a modified form of the invention; and 16 Fig. 4 is a view similar to Fig. 3, showing a further modification.

The embodiment illustrated in Fig. 1 comprises a furnace. l0 arranged to form a combustion chamber H, and a steam boiler l2 associated 2o therewith. The boiler is provided with banks of water tubes l4 and a battle l5 of usual construction, this baffle serving to direct the hot gases from the combustion chamber into proper contact with the water tubes and thence to a gas 25 outlet duct l6, which may lead to a suitable stack or induced draft fan (not shown). The outlet duct I6 is provided with a damper l8 having an operating arm IS. The boiler I2 is provided with the usual steam delivery pipe 20.

On the front of the furnace Hi there is mounted a burner 22 having a central fuel nozzle 23 arranged to direct a stream of fuel rearwardly into the combustion chamber ll through an opening 24 in the furnace wall. A suitable fluent 35 fuel, suchas a combustible gas, is supplied to the nozzle 23 at a pressure above atmospheric through a pipe 26 provided with a valve 21 having an operating lever 28. The burner 22 is of the natural draft type, the air for combustion being 40 I forced therethrough by the pressure of the atmosphere, a sub-atmospheric pressure being maintained in the combustion chamber II. The combustion chamber pressure, and hence the rate of air flow through the burner, is controlled by 45 means of the damper l8.

The fuel control valve 21 is regulated in accordance with the demand for heat, and for this purpose I preferably utilize an automatic regulator 30 of the type disclosed in the United States 50 patent to Temple No. 2,049,549. This regulator comprises a diaphragm chamber 3| and a motor 32. The diaphragm chamber 3| is connected by a pipe 34 to the steam delivery pipe 20, and the motor 32 is connected by a rod 35 to the valve 55 lever 28. The regulator thus serves to control .the valve 2'! in accordance with variations in the pressure of the steam in; the pipe 26.

In order to control the damper I8 there is provided a regulator 36 of the type disclosed in the United States patent to Temple No. 2,064,864. This regulator comprises a pilot valve 38 supplied with fluid under pressure from a suitable source through a pipe 39, the valve being connected by tubes 46 to a hydraulic motor 42 which is connected by a rod 43 to the arm [9 of the damper it. The pilot valve is actuated by a lever 44 which in turn is controlled by a pair of flexible diaphragms' 45 and 46 which-are joined centrallyby a connecting member 41. The weight of the diaphragms and'associated parts is balanced by. a coiled tension spring 49 which is adjustably supported by a nut 50 mounted on a screw 55.

The diaphragm 45 is subjected to an effective fluid pressure which is a function of the rate of supply of air to the furnace. For this purpose I connect the space above the diaphragm with the combustion chamber H by means of a pipe 52, and I connect the space below the diaphragm with the gas outlet duct [6 by means of a pipe 53. It will be apparent that with this construction the diaphragm is subjected to the pressure drop between the combustion chamber and the outlet duct, and that this pressure drop will increase as the air supply to the furnace is increased.

The diaphragm 46 is subjected to an effective pressure which is a function of the rate of fuel supply to the furnace. For this purpose there is provided a small pipe 55 through which a small stream of fuel is allowed to escape from the fuel pipe 26 at a point between the valve 21 and the burner 22 and thus from the zone immediately anterior to the burner. The escaping fuel is discharged into the combustion chamber, IJ just below the burner. This pipe 55 is provided with two restrictions, one of which is adjustable. For the first restriction there is shown an orifice plate 56, and for the second restriction there is shown an adjustable valve 51. The fuel pressure between the two restrictions is transmitted to the diaphragm 46 by means ofa pipe 58.

The operation of this embodiment of the invention will now be apparent from the above disclosure. Fuel flows to the burner nozzle 23 through the pipe 26, and the rate of flow is con- 58 to the diaphragm 46, providing an upward force thereon which is normally opposed and balanced by the downward force on the diaphragm 45 caused by the pressure difference between the combustion chamber II and gas outlet cluctl6; this pressure difference being transmitted through the pipes 52 and 53. The regulator 36 controls the damper H3 in such a way as to maintain a substantially balanced relationship between these forces. If'the steam pressure drops, the regulator 36 will open the valve 2?, increasing the fuel flow through the burner and through the pipe 55. This will increase the pressure on the diaphragm 46, throwing the to Temple No. 1,992,048.

regulator 36 slightly out of balance and causing the motor 42 to open the damper l8. This will cause more air to enter-the furnace to match the increased-fuel supply, and this will increase the pressure drop between the combustion chamber and'the gas outlet, thus increasing the force on the diaphragm 45 and restoring the regulator 36 to a balanced condition, whereupon the damper I 8 will come to .rest. If the heating value of the fuel changes, or if for any other reason it is desirable to change the ratio between the fuel and air supplies, it is merely necessary to adjust the valve '8. .This will change the rate of flow in the pipe 55 and thus change the pressure transmitted through the pipe 58, causing this pressure to bear a different ratio with respect to the fuel pressure at the burner.

In Fig. 3 there is illustrated a slightly modifled form of the invention in which a forced draft burner 22' is utilized, this burner being supplied with air at a pressure above atmospheric by means of a fan 66 connected to the burner by means of a duct 66. This duct is provided with a damper 62 having an operating arm 63 which is connected by a rod 64 to the motor 42 of the regulator 36. An orifice plate 66 is mounted within the duct 6! to provide a slight pressure differential for regulating purposes. A pipe 6? leads from the duct 6i anterior to the orifice plate to the space above the diaphragm 45, and a pipe 68 leads from the duct posterior to the orifice plate to the space below the diaphragm 45. The gas outlet damper I8 is preferably controlled to maintain a substantially constant pressure, slightly below atmospheric, in the combustion chamber H, and for this purpose I may use a regulator of the type disclosed in the patent This regulator is connected to the combustion chamber by a pipe H.

P16851116 fluid is supplied to the regulator I0 by I a pipe 13, and tubes 14 lead from the regulator to a hydraulic motor 15 which is connected by a rod 16 to the operating arm I9 of the damper I8.

The operation of this embodiment of the invention will now be, apparent from theabove disclosure. The regulator 36 controls the fuel valve 21- in accordance with the steam pressure, and a small stream of fuel flows through the pipe 55 at a rate va ying with the rate of fuel supply as indicated by the fuel pressure immediately anterior to the burner nozzle. tween the restrictions 56 and 51 is transmitted through the pipe 58 to the diaphragm 46 and provides an upward force which is normally balto maintain a substantially constant pressure in the combustion chamber ll.

In Fig. 4 there is illustrated a modification of the forced draft system in which the fuel pressure immediately anterior to the burner nozzle 23 is transmitted to the diaphragm 46 by means of a pipe 86. The orifice plate it omitted from the air duct 6i, and a pipe 8| is connected to this duct at a pointposterior to the damper 62 and thus at a zone immediately anterior to the burner. This pipe 6! is provided with two re- The pressure bestrictions, shown as an orifice plate 82 and a valve 83, the arrangement being such that a small stream of air will flow through the pipe and be discharged to atmosphere. The air pressure between the restrictions is transmitted to the diaphragm 45 by means of a pipe 84.

The operation of this embodiment will now be apparent. The regulator 30 controls the fuel valve 21 in accordance with the steam pressure,

and the pressure of the fuel anterior to the burner nozzle provides an upward force on the diaphragm 46 which is normally opposed and balanced by the downward force of the diaphragm 45 resulting from the air pressure transmitted thereto through the pipe 84. This air pressure is a measure of the rate of air supply to the burner 22', for if more air is supplied the pressure anterior to the burner will increase, increasing the rate of flow in the pipe 8| and causing a corresponding increase in the pressure in the pipe 84.

The pressure in the pipe 80 isa measure of the and reliable apparatus whereby the rate of combustion may be controlled in accordance with the demand for heat, and the proper ratio maintained between the supplies of fuel and air, this ratio being readily adjustable whenever desirable. This ratio adjustment is obtained without employing adjustable lever fulcrums or other similar mechanisms.

Having thus described my invention, what I .claim as new and desire to secure by Letters Patent is:

1. Control apparatus for a combustion system having a furnace burner and utilizing a fluent fuel and air as the elements of combustion comprising a device to control the flow of air, a motor to actuate the device, a pilot mechanism to control the motor, a fluid pressure responsive device connected to the pilot mechanism to actuate the same, means subjecting the fluid pressure responsive device to a fluid pressure which is a function of the rate of supply of one element of combustion, means supplying the other element of combustion to the burner at a pressure above atmospheric, a conduit through which a small stream of said other element may escape from a zone immediately anterior to the burner under the influence of the pressure in said zone, said conduit having two restrictions therein, means subjecting the fluid pressure responsive device to the fluid :pressure between said restrictions to maintain the fluid pressure responsive device in a substantially balanced condition, and means to adjust one of said restrictions and thereby adjust the ratio between the fuel and air supplies.

2. Control apparatus for a combustion system having a furnace burner and utilizing a fluent fuel and air as the elements of'combustion comprising a damper to control the flow of air, a motor to actuate the damper, a pilot mechanism to control the motor, a fluid pressure responsive device connected to the pilot mechanism to actuate the same, means subjecting the fluid pressure responsive device to a fluid pressure which is a function of the rate of supply of the air, means supplying the fuel to the burner at a pressure above atmospheric, a conduit through which a small stream of the fuel may escape from a'zone immediately anterior to the burner and thence past the burner to the combustion space under the influence of the pressure in said zone,'said conduit having two restrictions therein, means subjecting the fluid pressure responsive device to the fluid pressure between said restrictions'to maintain the fluid pressure responsive device in ea substantially balanced condition, and means to adjust one of said restrictions and thereby adjust the ratio between the fuel and air supplies.

3. Control apparatus for a combustion system having a furnace burner and utilizing a fluent fuel and air as the elements of combustion comprising means to supply both the fuel and the air to the burner at a pressure above atmospheric, a

damper anterior to the burner to control the flow of air, a motor to actuate the damper, a pilot mechanism to control the motor, a fluid pressure responsive device connected to the pilot mechanism to actuate the same, means subjecting the fluid pressure responsive device to a fluid pressure which is a function of the rate of supply of the air, a conduitthrough which a small stream of the fuel may escape from a zone immediately anterior to the burner and thence past the burner to the combustion space under the influence of the pressure in said zone, said conduit having two restrictions therein, means subjecting the fluid pressure responsive device to the fluid pressure between said restrictions to maintain the fluid pressure responsive device in a substantially balanced condition, and means to adjust one of said 1 restrictions and thereby adjust the ratio between the fuel and air supplies,

4. Control apparatus for a combustion system having a furnace burner and utilizing a fluent fuel and air as the elements of combustion comprising means to supply boththe fuel and the air to the burner at a pressure above atmospheric,

a damper anterior to the burner to control the flow of air, a motor to actuate the damper, a pilot mechanism to control the motor, a fluid pressure responsive device connected to the pilot mechanism to actuate the same, means subjecting the fluid pressure responsive device to the pressure of the fuel immediately anterior to the burner, a conduit through which a small stream of the air may escape from the zone between the damper

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