Frequency modulated burner system
First Claim
1. A combustion apparatus comprising:
- a combustion chamber;
at least a first burner operatively communicating with the combustion chamber;
a frequency modulated burner control system for cyclically actuating the burner at a selected, fixed burn rate and deactuating the burner, including;
(i) means for indicating a selected set point combustion chamber temperature;
(ii) means for sensing temperature in the combustion chamber;
(iii) error means for determining a deviation between the selected and sensed temperatures, the error means being operatively connected with the set point means and temperature sensing means; and
,(iv) duty cycle adjusting means for adjusting the burner actuation/deactuation ratio, the duty cycle means being operatively connected with the error means for adjusting the burner actuation/deactuation ratio in accordance with the deviation such that the frequency modulated burner control system controls thermal input from the burner.
1 Assignment
0 Petitions
Accused Products
Abstract
A furnace (A) defines a combustion chamber (10) in which a pair of burners (B) are mounted for oxidizing the fuel to heat the combustion chamber. An air blower (12) supplies air to the burners at a rate controlled by a rate control valve (18). A frequency modulated burner control system (C) controls the duty cycle of the burners, i.e. cyclically actuates the burner at a fixed burn rate and then deactuates them. The burner control system varies the actuation to deactuation ratio in each cycle to vary the thermal input to the combustion chamber. The burners provide two - stage combustion wherein a fuel rich mixture is partially oxidized in a first stage combustion area (44). Additional air which is thereafter introduced through air passages (50, 52) completes the combustion.
78 Citations
19 Claims
-
1. A combustion apparatus comprising:
-
a combustion chamber; at least a first burner operatively communicating with the combustion chamber; a frequency modulated burner control system for cyclically actuating the burner at a selected, fixed burn rate and deactuating the burner, including; (i) means for indicating a selected set point combustion chamber temperature; (ii) means for sensing temperature in the combustion chamber; (iii) error means for determining a deviation between the selected and sensed temperatures, the error means being operatively connected with the set point means and temperature sensing means; and
,(iv) duty cycle adjusting means for adjusting the burner actuation/deactuation ratio, the duty cycle means being operatively connected with the error means for adjusting the burner actuation/deactuation ratio in accordance with the deviation such that the frequency modulated burner control system controls thermal input from the burner. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method of combusting fuel
comprising: -
supplying fuel and air to a burner; cyclically actuating the burner to combust the fuel at a preselected burn rate and deactuating the burner; varying a duty cycle at which the burner is actuated at the fixed burn rate to vary the amount of heat produced, whereby the heat is controlled by varying a burner actuation/deactuation ratio of each cycle; sensing a temperature within a combustion chamber; determining a deviation between the sensed temperature and a selected temperature; and
,in the duty cycle varying step, adjusting the duty cycle in accordance with the sensed and selected temperature deviation. - View Dependent Claims (11)
-
-
12. A method of combusting fuel comprising:
-
supplying fuel and air to a burner; cyclically actuating the burner to combust the fuel at a preselected burn rate and deactuating the burner; varying a duty cycle at which the burner is actuated at the fixed burn rate to vary the amount of heat produced, whereby the heat is controlled by varying a burner actuation/deactuation ratio of each cycle; supplying fuel and air to a second burner; synchronizing actuation of the first and second burners by actuating the first burner at the beginning of each combustion cycle and deactuating the first burner during the cycle; and
,actuating the second burner during the cycle and deactuating the second burner at the end of the cycle, whereby actuation of the first and second burners is spread over eacy cycle.
-
-
13. A method of combusting fuel comprising:
-
supplying fuel and air to a burner; cyclically actuating the burner to combust the fuel at a preselected burn rate and deactuating the burner; varying a duty cycle at which the burner is actuated at the fixed burn rate to vary the amount of heat produced, whereby the heat is controlled by varying a burner actuation/deactuation ratio of each cycle; supplying air to the burner at a selected air supply rate; supplying fuel to the burner at a selected fuel supply rate; and
,adjusting a ratio of the air and fuel supplied to the burner. - View Dependent Claims (14)
-
-
15. A method of combusting fuel comprising:
-
supplying fuel and air to a burner; cyclically actuating the burner to combust the fuel at a preselected burn rate and deactuating the burner; varying a duty cycle at which the burner is actuated at the fixed burn rate to vary the amount of heat produced, whereby the heat is controlled by varying a burner actuation/deactuation ratio of each cycle; supplying a fuel rich mixture of the air and fuel to a first stage combustion area; partially combusting the fuel rich mixture in the first stage combustion area; and
,further combusting the partially combusted air and fuel mixture downstream from the first stage combustion area, whereby a two-stage combustion of the fuel is provided. - View Dependent Claims (16, 17)
-
-
18. A combustion apparatus comprising:
-
a combustion chamber; at least a first burner operatively communicating with the combustion chamber; a frequency modulated burner control system for cyclically actuating the burner at a selected, fixed burn rate and deactuating the burner such that the frequency modulated burner control system controls thermal input from the burner by controlling an actuation to deactuation ratio of each cycle; means for supplying air to the burner at a selectable air supply rate; means for supplying fuel to the burner at a selectable fuel supply rate; means for adjusting a ratio of air and fuel supplied to the burner, including; (i) means for measuring the flow rate at which the air supply means is supplying air to the burner; (ii) means for comparing the measured air supply flow rate with a desired air supply rate to determine a deviation therebetween, the air flow comparing means being operatively connected with the air flow measuring means; (iii) means for adjusting the selectable air supply rate in accordance with the deviation between the measured and desired air supply rates, the air supply rate adjusting means being operatively connected with the air flow comparing means; and
,means for periodically overriding the burner control system to cause the burner to be actuated for a calibration duration without regard to the combustion chamber temperature, the air supply rate adjusting means being operatively connected with the air/fuel ratio adjustment means to adjust the air/fuel ratio during the overriding.
-
-
19. A method of combusting fuel comprising:
-
supplying air to the burner at a selected air supply rate; supplying fuel to the burner at a selected fuel supply rate; cyclically actuating a burner to combust the fuel at a preselected burn rate and deactuating the burner; varying a duty cycle at which the burner is actuated at the fixed burn rate to vary the amount of heat produced, whereby the heat is controlled by varying a burner actuation/deactuation ratio of each cycle; adjusting a ratio of the air and fuel supplied to the burner; mesuring a rate at which air is being supplied to the burner; comparing the measured air supply rate with a desired air supply rate to determine a deviation therebetween; adjusting the air supply rate in accordance with the deviation between the measured and desired air supply rates; causing the burner to be actuated for a calibration duration of sufficient length to reach a steady state combustion condition without regard to the sensed temperature; and
,performing the air flow measuring step during the calibration duration such that the air supply rate is adjusted in accordance with the rate deviation measured during the steady state combustion condition.
-
Specification