Device for controlling the combustion of a burner

A combustion control device for a burner comprising a first inlet for the fuel, having an inlet valve for adjusting the quantity of fuel supplied, and a second inlet for the comburent, wherein the second inlet comprises a conveying duct extending along a respective axis of extension from a respective inlet end of the comburent, comprising a comburent flow regulator which adjusts the quantity of comburent supplied, the device comprising:

• a deflecting element for deflecting the incoming comburent configured for introducing the comburent in a radial direction relative to the axis of extension, wherein the deflector element is shaped in the form of a cap positioned on the inlet end of the comburent and having a respective internal cross-section larger than the cross-section the inlet end in such a way as to form a cylindrical air inlet zone between the conveying duct and the deflector element;
• a first sensor which measures the flow rate of the fuel which, in use, is supplied to the burner;
• a second sensor which measures the flow rate of the comburent which, in use, is supplied to the burner, the second sensor being positioned inside the deflector element;
• a first operator valve which controls the opening of the inlet valve as a function of the quantity of fuel to be supplied to the burner;
• a second operator valve which controls the comburent flow regulator as a function of the quantity of comburent to be supplied to the burner;
• a control unit for controlling the first operator valve and the second operator valve as a function of the values measured by the first sensor and by the second sensor;
• the control unit being configured to perform a second feedback check on the second valve by performing the following operations:
• generating an ideal flow rate value for the comburent as a function of the measured fuel flow rate according to a predetermined curve of values representing the relation between the ideal comburent flow rate and the fuel flow rate;
• measuring the flow rate of the comburent supplied to the burner;
• comparing the measured comburent flow rate value with the ideal comburent flow rate value and generating a corresponding offset value as a function of the difference between the measured comburent flow rate value and the ideal comburent flow rate value;
• and
• controlling the second operator valve to adjust the flow of the comburent into the second inlet as a function of the generated offset value in such a way that the measured comburent flow rate value approximates the ideal comburent flow rate value;
• wherein the control unit is configured to perform a first feedback check on the first operator valve by performing the following operations:
• generating an ideal flow rate value for the fuel as a function of the predetermined thermal power value for the burner and the measured comburent flow rate value, thereby adjusting a reference value for the fuel to the measured comburent;
• measuring the flow rate of the fuel supplied to the burner;
• comparing the measured fuel flow rate value with the ideal flow rate value and generating a corresponding offset value as a function of the difference between the measured fuel flow rate value and the ideal fuel flow rate value;
• and
• controlling the first operator valve to adjust the opening of the inlet valve as a function of the generated offset value in such a way that the measured fuel flow rate value approximates the ideal fuel flow rate value;
• wherein the control unit is configured to:
• define a ratio between the measured comburent flow rate value and the measured fuel flow rate value;
• compare this ratio with a predetermined range of safe combustion values;
• and
• if the ratio falls outside the predetermined range of safe combustion values, to control the first operator valve to close the inlet valve in order to shut down the burner;
• the first sensor and the second sensor comprising respective fuel and comburent conveyors, each extending along a fuel or comburent feed direction from a wide end to a narrow end in which a flow rate measuring sensor is mounted;
• said first sensor comprising one sensor configured to directly measure the flow rate of fuel and the second sensor comprising another sensor configured to directly measure the flow rate of the comburent;
• each of the first sensor and the second sensor being an anemometer of the hot film or hot wire type;
• and
• the conveyors being positioned inside the respective first inlet and second inlet and forming an internal passage section less than the section of the respective inlet in such a way that most of the fuel or comburent passes outside the respective conveyor.