Control network for burning fuel oil and gases with reduced excess air

Claim 2

A control network for simultaneous burning of liquid and gaseous fuels in a furnace under reduced excess air conditions comprising: servo-mechanism means for controlling the combustion air supplied to the combustion air inlet of said furnace; first means for sensing the amount of unburned solids exhausting from the flue of said furnace that characterize liquid fuel combustion quality; second means for sensing the amount of unburned gases exhausting from the flue of said furnace that characterize gaseous fuel combustion quality; first and second controller means having reference signals respectively reflecting complete burning of the liquid and the gaseous fuels associated with said first and second sensing means respectively for producing a signal output which is a function of the difference between said sensing means signal and said controller means reference signal; and, selector circuit means for transmitting the higher signal output of either said first or second controller means to said servomechanism means to vary the combustion air according to the higher signal to assure burning of the liquid and gaseous fuels.

Claim 3

A control network as set forth in claim 1 wherein said first sensing means includes an opacimeter for producing a signal which is a function of the capacity of the substances exhausting from the flue of said furnace blackened by unburned hydrocarbons of the fuel burned.

Claim 4

A control network as set forth in claim 2 wherein said second sensing means includes a gas analyzer for producing a signal which is a function of the reducing-gas content of the exhausting substances from said flue including unburned gas from the fuel burned.

Claim 5

A control network as set forth in claim 3 wherein said gas analyzer includes a carbon-monoxide analyzer and a hydrogen analyzer.

Claim 6

A control network as set forth in claim 4 wherein the fuel burned includes a fuel oil and a fuel gas burned simultaneously.

Claim 7

A control network for simultaneous burning of liquid and gaseous fuels in a furnace under reduced excess air conditions comprising: servo-mechanism means for controlling the combustion air supplied to the combustion air inlet of said furnace; first means for sensing and signaling the amount of unburned solids exhausting from the flue of said furnace that characterize liquid fuel combustion quality; second means for sensing and signaling the amount of unburned gases exhausting from the flue of said furnace that characterize gaseous fuel combustion quality; selector circuit means for monitoring and transmitting the higher signal sensed by said first and second sensing means; and, controller means having a reference signal that reflects a condition of complete fuels combustion with minimum excess air for producing a control signal to regulate said servo-mechanism means, said control signal being a function of the difference between the transmitted signal of said selector circuit means and the reference signal of said controller means.

Claim 8

A control network for simultaneous burning of liquid and gaseous fuels in a furnace under reduced excess air conditions comprising: servo-mechanism means for controlling the combustion air supplied to the combustion air inlet of said furnace; first means for sensing and signaling the amount of unburned solids exhausting from the flue of said furnace that characterize liquid fuel combustion quality; second means for sensing and signaling the amount of unburned gases exhausting from the flue of said furnace that characterize gaseous fuel combustion quality; selector circuit means for monitoring and transmitting the higher signal sensed by said first and second sensing means; and, controller means having a reference signal that reflects a condition of complete fuels combustion with minimum excess air for producing a control signal to regulate said servo-mechanism means, said control signal being a function of the difference between the transmitted signal of said selector circuit means and the reference signal of said controller means.

Claim 9

A control network as set forth in claim 6 wherein said first and second sensing means are scaled to produce identical output signals under proper combustion conditions; said controller means reference signal is set to be identical to the output signals of said first and second sensing means under proper combustion conditions.

Claim 10

A control network for simultaneoUs burning of liquid and gaseous fuels in a furnace under reduced excess air conditions comprising in order to minimize heat loss and heat exchanger corrosion: servo-mechanism means for controlling the combustion air supplied to the combustion air inlet of said furnace; first means for signaling the amount of unburned solids exhausting from the flue of said furnace that characterize liquid fuel combustion quality; second means for signaling the amount of unburned gases exhausting from said flue that characterize gaseous fuel combustion quality; selector circuit means for transmitting the higher signal of said first and second signaling means; controller means having a reference signal that reflects a condition of complete fuels combustion with minimum excess air and heat exchanger corrosion for producing an output signal which is a function of the difference between the transmitted signal of said selector circuit means and the reference signal of said controller means; third means for signaling the amount of at least one of the fuels flowing in the fuel inlet of said furnace; fourth means for signaling the amount of air flowing in the combustion air inlet of said furnace; and, summing circuit means for algebraically adding said third signaling means signal to the output signal of said controller means and said fourth signaling means signal to produce an output signal for controlling said servo-mechanism.

Claim 11

A control network for simultaneoUs burning of liquid and gaseous fuels in a furnace under reduced excess air conditions comprising in order to minimize heat loss and heat exchanger corrosion: servo-mechanism means for controlling the combustion air supplied to the combustion air inlet of said furnace; first means for signaling the amount of unburned solids exhausting from the flue of said furnace that characterize liquid fuel combustion quality; second means for signaling the amount of unburned gases exhausting from said flue that characterize gaseous fuel combustion quality; selector circuit means for transmitting the higher signal of said first and second signaling means; controller means having a reference signal that reflects a condition of complete fuels combustion with minimum excess air and heat exchanger corrosion for producing an output signal which is a function of the difference between the transmitted signal of said selector circuit means and the reference signal of said controller means; third means for signaling the amount of at least one of the fuels flowing in the fuel inlet of said furnace; fourth means for signaling the amount of air flowing in the combustion air inlet of said furnace; and, summing circuit means for algebraically adding said third signaling means signal to the output signal of said controller means and said fourth signaling means signal to produce an output signal for controlling said servo-mechanism.

Claim 12

A control network as set forth in claim 8 including an amplifying means for the output signal of said summing circuit means.

Claim 13

A control network as set forth in claim 9 wherein said summing circuit means adds said third signaling means signal to the output signal of said controller means and subtracts said fourth signaling means signal therefrom.

Claim 14

A control network as set forth in claim 10 wherein said third signaling means includes a gas flow signaling means and an oil flow signaling means.

Claim 15

A control network for burning liquid fuel and gaseous fuel in the same furnace under reduced excess air conditions comprising: servo-mechanism means for controlling the amount of combustion air flowing in the liquid and gaseous fuel associated air inlets of said furnace; first means for signaling the amount of unburned residue exiting from the flue of said furnace; second means for signaling the amount of combustion air flowing in the air inlets of said furnace; third means for signaling the amount of fuel flowing in the fuel inlets of said furnace; summing circuit means for algebraically adding the signals from said first, second and third signaling means to produce output signals suitable for controlling said servo-mechanism means; said first signaling means includes an opacimeter signaling the amount of unburned solids exiting from the flue of said furnace that characterize liquid fuel combustion and a gas analyzer signaling the amount of unburned gases exiting from the flue of said furnace that characterize gaseous fuel combustion; said second signaling means includes a first and second air flow meter signaling the rate of air flow to the fuel associated air inlets of said furnace; said third signaling means includes a liquid fuel flow meter and a gaseous fuel flow meter signaling the rate of flow of the respective fuels; said servo-mechanism means includes a first servo-mechanism controlling the air flow in the liquid fuel associated air inlet and a second servo-mechanism controlling the air flow in the gaseous fuel associated air inlet of said furnace; and, said summing circuit means includes a first summing circuit adding the signals from the liquid fuel flow meter, the opacimeter and the first air flow meter to control the first servomechanism and adjust the liquid fuel excess air flow, and a second summing circuit adding the signals from the gaseous fuel flow meter, the gas analyzer and the second air flow meter to control the second servo-mechanism and adjust the gaS fuel excess air flow thereby.

Claim 16

A control network for burning liquid fuel and gaseous fuel in the same furnace under reduced excess air conditions comprising: servo-mechanism means for controlling the amount of combustion air flowing in the liquid and gaseous fuel associated air inlets of said furnace; first means for signaling the amount of unburned residue exiting from the flue of said furnace; second means for signaling the amount of combustion air flowing in the air inlets of said furnace; third means for signaling the amount of fuel flowing in the fuel inlets of said furnace; summing circuit means for algebraically adding the signals from said first, second and third signaling means to produce output signals suitable for controlling said servo-mechanism means; said first signaling means includes an opacimeter signaling the amount of unburned solids exiting from the flue of said furnace that characterize liquid fuel combustion and a gas analyzer signaling the amount of unburned gases exiting from the flue of said furnace that characterize gaseous fuel combustion; said second signaling means includes a first and second air flow meter signaling the rate of air flow to the fuel associated air inlets of said furnace; said third signaling means includes a liquid fuel flow meter and a gaseous fuel flow meter signaling the rate of flow of the respective fuels; said servo-mechanism means includes a first servo-mechanism controlling the air flow in the liquid fuel associated air inlet and a second servo-mechanism controlling the air flow in the gaseous fuel associated air inlet of said furnace; and, said summing circuit means includes a first summing circuit adding the signals from the liquid fuel flow meter, the opacimeter and the first air flow meter to control the first servomechanism and adjust the liquid fuel excess air flow, and a second summing circuit adding the signals from the gaseous fuel flow meter, the gas analyzer and the second air flow meter to control the second servo-mechanism and adjust the gaS fuel excess air flow thereby.