US2794599A

US2794599A - Fuel feeding control system

Info

Publication number: US2794599A
Application number: US322129A
Authority: US
Inventors: Irwin William
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-11-22
Filing date: 1952-11-22
Publication date: 1957-06-04
Anticipated expiration: 1974-06-04

Description

June 4, 1957 w, lRwlN FUEL FEEDING CONTROL SYSTEM BOILER Filed NOV. 22, 1952 TO OIL BURNER MOTOR AND IGNITION CIRCUIT INVENTOR W. IRWIN II II II l II II II II L OIL TANK ATTORNEY 2,794,599 FUEL FEEDENG CONTROL SYSTEM William Irwin, Brooklyn, N. Y.

Application November 22, 1952, Serial No. 322,129

7 Claims. (Cl. 236-46) This invention relates to a fuel feeding system for oil burners and more particularly to a high-low oil and air supply and control systiem for steam generating boilers.

I-leretofore it has been proposed in oil burning systems to provide a normally open electrically operated or pressure controlled valve in the burner inlet conduit for providing the principal fuel for high operation and an orificed by-pass about the valve which supplies the fuel for low operation when the burner goes on control, that is, upon closing of the valve in response to a predetermined pressure in the boiler. While this arrangement may be termed a high-low system, it is not effective as such for the reason that the amount of oil supplied when the burner is on control should not be greater than that required to maintain steam pressure in the boiler under no-load conditions. This arrangement also requires a master valve which cuts ofi the coil completely when the pressure for any reason exceeds a prescribed value.

in a true high-low system two solenoid valves are ordinarily employed, each of which feed oil to the burner. These valves may be suitably controlled to obtain any desired relationship between the high and low flame. This arrangement, however, has the disadvantage that each solenoid valve must operate with a high degree of precision to insure that the valve is set perfectly upon its seat when the circuit to its solenoid is interrupted so that there will be no leakage and consequent accumulation of oil in the fire box during idle periods of the burner.

The present invention is directed to a true high-low burner system, one of the objects of the invention being to provide such a system in which only a single electric valve will be required in the burner line.

Another object is to provide such a system in which the burner will always start on low flame even though high flame is called for.

Still another object is to provide a burner control system which is inexpensive to produce and install, simple to maintain and operate, and which will be free of the mechanical gearing and linkage usually incident to highlow control systems.

In accordance with the present invention I employ a normally closed, electrically operated primary oil valve in the burner line, which is of sufiicient capacity to supply all of the oil required for either high or low operation, in series arrangement with either an orificed or hand adjustable valve for quantitatively determining the oil flow to the burner under a predetermined pressure in the burner supply line. This primary oil valve must be of sufficient quality to shut off completely when its energizing circuit is open. A second and normally open electric valve is provided in the oil return line and serves in its open and closed positions, respectively, to determine either low or high operation of the burner.

The invention will best be understood by reference to the accompanying drawing in which:

Fig. 1 shows an oil burner and fuel supply system therefor embodying the present invention; and

atent Fig. 2 shows a modified embodiment.

In the drawing an oil burner 10 is shown, which may be of any conventional type, such as a horizontal rotary burner having unitary blower 11, geared pump 12 and rotary nozzle 13, all driven by a motor contained within the housing 14. Oil is supplied to the burner from a supply tank 15 and conduit 16 leading to the suction side of the pump 12, the oil line continuing from the output of the pump through conduit '17, normally closed sole noid valve 18 and manual quantity adjusting valve 19 to theinput of the burner 10. The valve 18, as stated, is of suflicient capacity to pass the full supply of oil required for high operation of the burner. It does not serve, however, to control quantitatively the amount of oil passed to the burner but merely to open fully when its solenoid is energized and to close completely when its solenoid is deener gized.

A by-pass is provided from the output side of the pump 12 to the tank 15 comprising

conduits

20 and 21 containing a normally open solenoid valve 22, a gate or fiow regulating valve 23, and a pressure relief valve 24. A second by-pass 25 between the outlet side of the pump 12 and the tank 15 includes a pressure relief valve 26. It is to be understood that while the by-passes have been shown going to the tank 15, they could equally well be returned to the suction side of the pump 12.

With the arrangement shown it will be evident that with the valve 18 open in response to a call for heat, the flow of oil therethrough to the burner will depend upon the pressure in the conduit 17 and the setting of manual valve 19. With valve 22 closed, maximum pressure will be supplied as determined by the setting of the pressure relief valve 26 in by-pass 25, and consequently maximum fuel will be supplied to the burner 10 to cause it to operate at high flame. However, with the valve 22 open, a portion of the oil supplied by the pump 12 will be diverted through the valve 22 and the pressure in the line 17 will be reduced accordingly to a minimum pressure, as determined by the adjustment of the pressure relief valve 24 which, as will be understood, is set to operate at a lower value than relief valve 26. This reduced pressure in line 17 will cause a smaller oil flow to the burner 19, corresponding to the desired low flame condition.

The blower 11 incorporated in the burner is adjusted to supply sufiicient air for the low flame condition only and, therefore, when valve 22 is closed to provide the high flame condition, it is necessary to supply supplemental air to the firing chamber. This is accomplished by a secondary blower 27 having an electric timer 28 in series in the blower motor circuit and its normally open contacts in series in the operating circuit of solenoid valve 22 so that the latter valve can not close until a predetermined time after starting of the blower.

The high-low firing conditions are controlled by the boiler pressure through two pressure operated

switches

31 and 32, which are shown as of the mercury type. Switch 31 controls the opening and closing of solenoid valve 18 and switch 32 controls the opening and closing of solenoid valve 22. By way of example, if it is desired to maintain a maximum boiler pressure of 16 pounds of steam, the switch 31 will be adjusted to open at 16 pounds pressure and to reclose when the pressure is reduced to 14 pounds. In order to prevent overrunning of the boiler pressure and to decrease the frequency of operation of the controls, the switch 32 is adjusted to open at a pressure below the pressure at which switch 31 opens, say, 15 /2 pounds, and to reclose at a pressure slightly higher than that at which valve 31 recloses, say, 14 /2 pounds. The sequence of operation of the

pressure switches

31 and 32 and the

oil control valves

18 and 22 will be described subsequently.

3 Mercury switch 31 when closed connects power from the high side of line L through contact 1 of a thermal delay switch 33, the bridging contact 34 of the switch, contact 2 and conductor 35 to the winding of solenoid switch 13, and thence by conductor 36 and delay switch contact 3 to the grounded side of the line. The heating coil 37 of delay switch 33 is connected from power to ground across contacts 1 and 3. As a consequence, upon closing of mercury switch 31 there is a delay of from 20 to 50 seconds before closing of contact 34 to energize the solenoid valve 18.

Auxiliary blower 27 is energized from line L, contact 34, switch 32, when closed, conductor 39, motor of blower 27 and electric timer 28 to ground. Timer 28, after a slight delay, completes a circuit to valve 22, through the air flow actuated switch 44 of blower 27, in parallel to the blower 27.

The operation of the system is as follows: With pressure in the boiler below the desired maximum of,,say, 16 pounds,

mercury switches

31 and 32 will be closed. Let it be assumed that the boiler is cold and the main line Power will then be supplied through the mercury switch 31, terminal 1 of the thermal delay switch and conductor 43 over conventional burner circuits, not shown, to energize the motor of the burner 10 and the burner ignition. Warp switch contact 34 will be open at this time but after switch 42 is closed to start the system into operation.

time delay the timer 28 operates, closing solenoid valve 22, providing blower 27 is properly operating to close contacts 44. Prior to the closing of valve 22 the pressure in the line 17 is that corresponding to low flame, as determined by the relief valve 24. Therefore, upon opening of the valve 18 the burner 14 starts under low flame fuel supply conditions. This starting on low flame is a safety precaution and the adjustment of the electric timer 28 should be such that the burner nozzle will be heated up and the low flame combustion condition stabilized before the larger flow of fuel resulting from the closing of valve 22 starts. It also insures the provision of an adequate supply of air from blower 27 at the time this additional fuel is supplied. As a consequence, the development of maximum oil pressure in conduit 17 is delayed for a short interval after which ates on high flame. When the pressure in the boiler approaches the desired maximum pressure of 16 pounds, that is, switch 32 opens its contacts interrupting the circuit to blower 27 and solenoid valve reducing the pressure in oil line 17 to thereby produce the low flame condition, and the secondary air supply from blower 27 is interrupted. Under normal load conditions the steam pressure in the boiler will stop rising before the cut-off pressure of 16 pounds is reached, or will rise at a much slower rate so that the operating period of the burner will be prolonged. If the maximum pressure of 16 pounds is ultimately reached, mercury switch 31 will open and the entire burner system will shut down and remain in that condition until the pressure has reduced to the cut in pressure which in the present example was given at 14 pounds. on such occurrence switch 31 recloses and the system restarts as previously described. Normally, however, ,on opening of mercury switch 32 the boiler pressure will slowly decrease, the rate of decrease depending on the magnitude of the low flame condition. If this is adjusted to a value which will almost carry the normal load, the rate of decrease of boiler pressure will be slow and'the period of operation on low flame correspondingly prolonged. However, when the pressure has decreased to a point approaching the minimum desired pressure of, say, 14 pounds, that is, a decrease to about 14 /2 pounds, mercury switch 32 will at 15 /2 pounds in the example given, mercury the burner oper- 22. Valve 22 thus opens,

again close its contacts to restart the blower 27 followed by energization of the normally open solenoid valve 22 to close the same, restoring high flame conditions in the burner. Thus the burner may be operated over long periods between high and low flame conditions without the loss of efliciency which results from frequent starting of the burner, and at the same time maintain the boiler pressure between closely spaced upper and lower limits.

Since only ,a single electric cut-ofi valve is provided in the burner fuel line, the system requires but one precision valve. The secondary electric valve 22 does not need to cut off accurately and may, therefore, be of an inexpensive type.

It will be noted, in the system of Fig. 1, that the fuel flow to the burner 14 is dependent upon the pressure created in the line 17, as controlled by the open or closed condition of electric valve 22. In Fig. 2 I have shown diagrammatically an arrangement in which the fuel flow to the burner is under uniform pressure for both high .and low 'flow conditions, the quantity of oil supplied to the burner being determined by the orifice size of the sup- 1 ply conduits. In this form the pump 12' is supplied with a return conduit 25' containing a pressure return valve 26" for determining the pressure at which the fuel is supplied to the burner 14, through the electric valves 22' A by-pass 45 extends around valve 22 and orifice 47 is located at the input side of electric valve 22'. The control circuit for the secondary blower 27 and valves 18' and 22' is the same as that shown in Fig. l for the blower 27 and

valves

18 and 22. Thus, in the modification of Fig. 2, when low heat is' called for, valve 18' will be open and valve 22' closed, the low fuel supply being determined by the setting of orifice 46. When high heat is called for, blower 27' first operates, followed by the opening of valve 22', the fuel flow then being determined by the aggregate size of orifice 46 and orifice 47.

While the invention has been described with reference to controlling boiler pressure, it is to be understood that it applies equally well to temperature control in which case the mercury switches 31 and 32 would be thermally -controlled rather than pressure controlled. Other variations and arrangements of the essential elements of the a steam generating boiler comprising a fuel pump, a conduit extending from the output side of said pump for sup- Iplying fuel under pressure to said burner, a normally "closed electrically-operated valve in said conduit, a bypass conduit extending from the output to the input side of said pump, a normally open electrically operated valve in said by-pass conduit, and energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a first predetermined maximum and minimum pressure in said boiler for respectively deenergizing and energizing said normally closed valve and said second control switch being responsive to a second predetermined maximum and minimum'pressure in said boiler for respectively deenergizing and energizing said normally open valve, said second maximum and minimum pressures falling Within said first maximum and minimum pressures.

2. A high-low fuel feeding system for the oil burner of a steam generating boiler comprising a fuel pump, a conduit extending from the output side of said pump for supplying fuelunder pressure to said; burner, a normally closed electrically operated valve in said conduit, a bygreases pass conduit extending from the output to the input side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a first predetermined maximum and minimum pressure in said boiler for respectively deenergizing and energizing said normally closed valve and said second control switch being responsive to a second predetermined maximum and minimum pressure in said boiler for respectively deenergizing and energizing said normally open valve, said second maximum and minimum pressures falling within said first maximum and minimum pressures, a pressure relief valve in said by-pass for determining the maximum pressure present in said conduit when said normally open valve is open, 'a second by-pass between the outlet and inlet sides of said pump, and a pressure relief valve in said second by-pass for determining the maximum pressure present in said conduit when the normally open valve is closed.

3. A high-low fuel feeding system for an oil burner comprising a fuel pump, a conduit extending from the outlet of said pump for supplying fuel under pressure to said burner, a normally closed electrically operated valve in said conduit, a by-pass conduit extending from the outlet to the inlet side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a call for high fuel by said burner to energize said normally closed valve to open the same and said second control switch being responsive to a call for high fuel by said burner to energize said normally open valve to close the same, said second control switch also being responsive to a call for low fuel, while said first control switch is responding to a call for high fuel, to deenergize said normally open valve while said normally closed valve is energized to remain open.

4. A high-low fuel feeding system for an oil burner comprising a fuel pump, a conduit extending from the outlet of said pump for supplying fuel under pressure to said burner, a normally closed electrically operated valve in said conduit, a by-pass conduit extending from the outlet to the inlet side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a call for high fuel by said burner to energize said normally closed valve to open the same and said second control switch being responsive to a call for high fuel by said burner to energize said normally open valve to close the same, said second control switch also being responsive to a call for low fuel, while said first control switch is responding to a call for high fuel, to deenergize said normally open valve while said normally closed valve is energized to remain open, and a pressure relief valve in said by-pass for determining the maximum pressure present in said conduit when said normally open valve is open.

5. A high-low fuel feeding system for an oil burner comprising a fuel pump, a conduit extending from the outlet of said pump for supplying fuel under pressure to said burner, a normally closed electrically operated valve in said conduit, a by-pass conduit extending from the outlet to the inlet side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a call for high fuel by said burner to energize said normally closed valve to open the same and said second control switch being responsive to a call for high fuel by said burner to energize said normally open valve to close the same, said second control switch also being responsive to a call for low fuel, while said first control switch is responding to a call for high fuel, to deenergize said normally open valve While said normally closed valve is energized to remain open, a pressure relief valve in said by-pass for determining the maximum pressure present in said conduit when said normally open valve is open, a second bi-pass between the outlet and inlet sides of said pump, and a pressure relief valve in said second by-pass for determining the maximum pressure present in said conduit when the normally open valve is closed.

6. A high-low fuel feeding system for an oil burner comprising a fuel pump, a conduit extending from the outlet of said pump for supplying fuel under pressure to said burner, a normally closed electrically operated valve in said conduit, a by-pass conduit extending from the outlet to the inlet side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a call for high fuel by said burner to energize said normally closed valve to open the same and said second control switch being responsive to a call for high fuel by said burner to energize said normally open valve to close the same, said second control switch also being responsive to a call for low fuel, while said first control switch is responding to a call for high fuel, to deenergize said normally open Valve while said normally closed valve is energized to remain open, and means for delaying the closing of said normally open valve in response to a call for high fuel, until after the opening of said normally closed valve.

7. A high-low fuel feeding system for an oil burner comprising a fuel pump, a conduit extending from the outlet of said pump for supplying fuel under pressure to said burner, a normally closed electrically operated valve in said conduit, a by-pass conduit extending from the outlet to the inlet side of said pump, a normally open electrically operated valve in said by-pass conduit, energizing circuits for said valves including a first control switch common to said valves and a second control switch individual to said normally open valve, said first control switch being responsive to a call for high fuel by said burner to energize said normally closed valve to open the same and said second control switch being responsive to a call for high fuel by said burner to energize said normally open valve to close the same, said second control switch also being responsive to a call for low fuel, while said first control switch is responding to a call for high fuel, to deenergize said normally open valve while said normally closed valve is energized to remain open, means for delaying the :closing of said normally open valve in response to a call for high fuel, until after the opening of said normally closed valve, a pressure relief valve in said by-pass for determining the maximum pressure present in said conduit when said normally open valve is open, a second by-pass between the outlet and inlet sides of said pump, and a pressure relief valve in said second by-pass for determining the maximum pressure present in said conduit when the normally open valve is closed.

References Cited in the file of this patent UNITED STATES PATENTS 1,425,338 Ray Aug. 8, 1922 2,016,805 Kinnan Oct. 8, 1935 2,179,846 Finnigau Nov. 14, 1939 2,240,059 Thoresen Apr. 29, 1941 2,476,701 Cochrane July 19, 1949 2,637,165 Stockinger May 5, 1953