Title:
COMBUSTION CONTROL DEVICE
United States Patent 3843310


Abstract:
A device for controlling the variation of power stage of the gas burners as a function of the variation of the pressure of the feed gas characterized by a pressure sensitive device which in response to two or more values of the gas pressure will close or open circuits which, by means of the predisposed programs on the control board, will act on the power operated valve or electrovalve that chokes the gas, and will adjust the gas feed changing the power state of the burner.



Inventors:
MASSI G
Application Number:
05/394196
Publication Date:
10/22/1974
Filing Date:
09/04/1973
Assignee:
MASSI G,IT
Primary Class:
Other Classes:
137/487.5
International Classes:
F17D1/04; F23D14/60; (IPC1-7): F23N1/02
Field of Search:
431/89,90,12 137
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US Patent References:



Primary Examiner:
Favors, Edward G.
Attorney, Agent or Firm:
Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Sampson
Claims:
I claim

1. A device for controlling the variations of a power stage of a gas burner as a function of the variation of the pressure of the gas being supplied thereto, said device comprising an electrovalve for choking the flow of gas in a conduit extending to the burner, a pressure sensitive device arranged to sense the pressure of the gas flowing in said conduit, and circuit means interconnecting said pressure sensitive device and the electrovalve which circuit means include a control board containing a predetermined program, said pressure sensitive device in response to at least two values of said gas pressure opening and closing said circuits to actuate the electrovalve so that the rate of gas feed to the burner is adjusted to change the power state thereof, said burner conduit having a by-pass line extending to a head of the burner to provide a pilot flame, said by-pass link including means for controlling flow therethrough, and wherein said pressure sensitive element also controls operation of the means for controlling flow in the by-pass line in response to the sensed pressure to enhance the variation in the rate of flow caused by operation of the electrovalve.

2. A device according to claim 1, wherein said burner is a blown air burner having an air inlet duct provided with a choking valve for regulating the flow of air through the inlet and wherein said electrovalve includes means for adjusting the setting of the choking valve in response to changes in the rate of gas flow through said electrovalve so that the desired air-gas ratio for maximum combustion efficiency is maintained for variation in the amount of gas supplied to the burner.

3. A device according to claim 2, wherein said means for adjusting comprises a power operated adjusting device on said choking valve and a servo attached to said electrovalve to control said adjusting device.

4. A device according to claim 2, wherein said means for adjusting comprises a mechanical linkage interconnecting the choking valve to the electrovalve.

5. A device for controlling the variations of a power stage of a gas burner as a function of the variation of the pressure of the gas being supplied thereto, comprising an electrovalve for choking the flow of gas in a conduit extending to a head of the burner, said conduit having a by-pass line to provide a pilot flame and including means for controlling flow therethrough and a pressure sensitive element arranged to sense the pressure of the gas flowing in said conduit and to control the operation of said means for controlling the flow in the by-pass line in response to the sensed pressure to enhance the variation in the rate of flow caused by operation of said electrovalve.

6. A device according to claim 5, wherein said burner is a blown air burner having an air inlet duct provided with a choking valve for regulating the flow of air through the inlet and wherein said electrovalve includes means for adjusting the setting of the choking valve in response to changes in the rate of gas flow through said electrovalve so that the desired air-gas ratio for maximum combustion efficiency is maintained for variation in the amount of gas supplied to the burner.

7. A device according to claim 6, wherein said means for adjusting comprises a power operated adjusting device on said choking valve and a servo attached to said electrovalve to control said adjusting device.

8. A device according to claim 6, wherein said means for adjusting comprises a mechanical linkage interconnecting the choking valve to the electrovalve.

Description:
The present invention relates to a device to be applied to the burners for town gas for controlling the combustion during the peaks of maximum absorption from the distribution network.

The purpose of this invention is that of obtaining the automatic reduction of the fuel request or demand by the gas burners when the pressure in the town distribution network decreases below the usual values due to an excess of request or demand.

Another purpose is to maintain the ratio of the air-gas mixture in the blown air burners, when the pressure changes, and therefore changes the rate of flow of the gas, so as to obtain both optimum efficiencies for the burners and a correct combustion therein.

At present, the blownair burners do not adjust the amount of the air supporting the combustion to compensate for changes in gas pressure. Thus, any changes in the rate of flow of the fuel is not adjusted by the amount of air being introduced by the burner.

In the distribution networks of the towns, on the contrary, periodical falls and raisings of the gas pressure occur as a function of the demand on the distribution network of the gas distributing system. The amount of fluctuation to an individual consumer also depends on the location of the consumer in the network.

The stabilization of the pressure by means of reducers stabilizers creates losses of pressure which, during the moments of maximum absorption or demand, add to the losses which already exist in the cuts, to increase the possibility of jamming of the burners. Moreover, the excessive variations of gas pressure, and therefore of the rate of flow of the fuel, causes a variation of the ratio of air-gas mixture and thereby an irregular combustion which causes a decrease of the efficiency, the formation of carbon monoxide, and the possibility of jammings due to intervention of the flame detector.

The present invention provides a device for overcoming said drawbacks, by reducing automatically the power required by the burner when the pressure in the gas distributing network diminishes, and by adjusting the rate of flow of the combustion supporting air, to each rate of flow of the fuel, so as to maintain the air-gas mixture within the limits or ratio which is necessary for a correct combustion of the fuel.

In the drawings:

FIG. 1 diagrammatically illustrates the device according to this invention applied to a blow-air burner;

FIG. 2 illustrates an embodiment of the device of FIG.1;

FIG. 2A is a side view of the burner of FIG. 2;

FIG. 2B is a plan view with portions in cross section of the burner of FIG. 2A;

FIG. 2C is a plan view of the contral valves and connecting conduits for the burner of FIG. 2B;

FIG. 3 diagrammatically illustrates the invention when applied to a burner of the so-called "atmospheric" type.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles of the present invention are particularly useful in the embodiment diagrammatically illustrated in FIG. 1 which shows by way of a non-limitative example one preferred embodiment of the invention.

As illustrated, the gas flow is received by a cut-off faucet or valve 1 which is connected to a safety electrovalve 2. A pressure switch 3 is associated with the valve 2 and operates in case of a lack of gas pressure to close the valve 2. From valve 2, the gas flows through a conduit to a multiple position electrovalve or power operated valve 4 which is associated with a control valve or faucet 5. A by-pass conduit or line 11 is connected to a Tee provided in the conduit extending between valves 2 and 4 and the by-pass conduit is provided with an electrovalve 7 and a contral valve or faucet 8. The by-pass conduit supplies gas to the pilot flame of a burner head 6 of the burner. The head 6 is received in a tubular part of a casing 12 of the burner (FIG. 2B). As illustrated in FIG. 1, the casing 12 contains an air choking valve 9 whose setting is controlled by means of a mechanical linkage interconnecting the valve 9 to the valve 4.

This invention provides a pressure sensitive element 10 which has contacts 13. When the pressure is normal, the element 10 allows the burner to operate according to its usual characteristic cycle, which includes pre-heating, starting, continuous running and shut off stages. Under a reduced pressure, which has a value determined or pre-selected by adjustments provided with the element 10, the contacts 13 of the element 10 will open a circuit of a control board which applies a partial choking program on the valve 4 and also shut-off the valve 7 of the by-pass. Thus, the burner will operate at reduced rate of flow for the running stage and this reduced rate can be pre-established at will by acting on the adjustment of the main valve 4. Simultaneously, the mechanical control linkage, which interconnects the air choking valve 9 to the valve 4, will adjust the air choking valve 9 to adjust the amount of air being supplied to the burner to be the amount required for the combustion of the amount of gas entering into the burner 6.

When the pressure raises above the normal value, necessarily the rating of the combustion would unavoidably become incorrect, due to an excessive supply of the gas to the burner, to which no adequate rate of flow of combustion supporting air would correspond. This drawback will be automatically removed by the control mechanism which by means of the closure of the contacts 13 will provide a partial shut-off of the valve 4 and total shut-off of the valve 7 to thereby prevent an excessive amount of gas from reaching the burner.

In the embodiment of FIG. 2, the air choking valve 9 is connected to a power operated adjusting device M controlled by a servo 14 associated to the valve 4. When the valve 4 controls the rate of flow to the burner, the valve 4 by means of the servo 14 and device M controls the setting of the air choking valve.

In case of an induced air burner 15 (FIG. 3) which burners are also called atmospheric burners or sucked air burners, the pressure sensitive element 10 is inserted upstream of the atmospheric burner 15 in the conduit extending thereto. The position, which is shown in FIG. 3, is only for exemplary purposes. The position of the element 10 in the conduit can change in relation to the adjusting valve 4, shut-off valve 1 and safety device 2 which are provided for the various kinds of burners and to which the burner can be associated.

The sensitive element 10 by means of an electric or mechanical connection, or a connection of another kind, acts on the choking valve 4 compeling it to take a reduced aperture position, when the gas pressure decreases under a normal value, which is pre-established by setting of the adjustment on the sensitive element 10. When the value of the gas pressure is above a normal preestablished value, the element 10 will also transmit a control function to the valve 4.

Although minor modifications might be suggested by those versed in the art, it should be understood that I wish to employ within the scope of the patent warranted herein all such modifications as reasonably and properly come within the scope of my contribution to the art.