Device and method for controlling a fuel-oxidizer mixture for a premix gas burner

A method for controlling a fuel-oxidizer mixture in a premix gas burner, comprising the following steps:

• generating an air flow, by means of a fan, in an intake duct including an inlet for receiving the oxidizer, a mixing zone, and an outlet for delivering the mixture to the burner;
• feeding fuel to the mixing zone through an injection duct;
• mixing the oxidizer and the fuel in the mixing zone;
• regulating the fuel flow rate through a gas regulating valve;
• generating drive signals through a control unit and sending the drive signals to the gas regulating valve and to the fan;
• detecting a first differential pressure, between a first detecting section, located in the intake duct upstream of the mixing zone in the direction of inflow and a second detecting section, located in the intake duct downstream of the mixing zone in the direction of inflow;
• detecting a second differential pressure, between the first detecting section and a third detecting section, located in the injection duct between the gas regulating valve and the mixing zone;
• providing a first pressure connection, a second pressure connection and a third pressure connection;
• and
• inserting the first pressure connection, the second pressure connection and the third pressure connection into a first, a second and a third through cavity of the mixer, respectively,
• wherein the first, the second and the third through cavity are open onto the first detecting section, the second detecting section and the third detecting section, respectively.

A device for controlling a fuel-oxidizer mixture for a premix gas burner, comprising:

• an intake duct, which defines a section for the admission of an oxidizer fluid into the duct and includes an inlet for receiving the oxidizer, a mixing zone for receiving the fuel and allowing it to be mixed with the oxidizer, and an outlet for delivering the mixture to the burner;
• an injection duct, which defines a section for the admission of the fuel and which is connected to the intake duct in the mixing zone to supply the fuel;
• a gas fuel regulating valve, located along the injection duct;
• a fan, located in the intake duct to generate therein a flow of the oxidizer fluid or of the fuel-oxidizer mixture in a direction of inflow oriented from the inlet to the delivery outlet;
• a control unit, configured for generating drive signals, for regulating the gas regulating valve and the rotation speed of the intake fan;
• a sensor unit, in communication with the control unit and configured for detecting
• a first differential pressure, between a first detecting section, located in the intake duct upstream of the mixing zone in the direction of inflow and a second detecting section, located in the intake duct downstream of the mixing zone in the direction of inflow, and
• a second differential pressure, between the first detecting section and a third detecting section, located in the injection duct between the gas regulating valve and the mixing zone,
• wherein the control unit is programmed for:
• commanding a predetermined flow rate variation by regulating the fan or the gas regulating valve;
• detecting a first variation, representing a variation in the first differential pressure due to the predetermined flow rate variation;
• detecting a second variation, representing a variation in the second differential pressure due to the predetermined flow rate variation;
• and
• performing a diagnosis of the sensor unit based on the first and the second variation.

A method for controlling a fuel-oxidizer mixture in a premix gas burner, comprising the following steps:

• generating an air flow, by means of a fan, in an intake duct including an inlet for receiving the oxidizer, a mixing zone, and an outlet for delivering the mixture to the burner;
• feeding fuel to the mixing zone through an injection duct;
• mixing the oxidizer and the fuel in the mixing zone;
• regulating the fuel flow rate through a gas regulating valve;
• generating drive signals through a control unit and sending the drive signals to the gas regulating valve and to the fan;
• detecting a first differential pressure, between a first detecting section, located in the intake duct upstream of the mixing zone in the direction of inflow and a second detecting section, located in the intake duct downstream of the mixing zone in the direction of inflow;
• and
• detecting a second differential pressure, between the first detecting section and a third detecting section, located in the injection duct between the gas regulating valve and the mixing zone,
• wherein the method further comprises a step of diagnosing, including the following steps, performed by a processor of the control unit:
• commanding a predetermined flow rate variation by regulating the fan or the gas regulating valve;
• detecting a first variation, representing a variation in the first differential pressure due to the predetermined flow rate variation;
• detecting a second variation, representing a variation in the second differential pressure due to the predetermined flow rate variation;
• and
• performing a diagnosis of a sensor unit based on the first and the second variation.