Premix Burner Air-Gas Control With Variable Intake Geometry
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Solution Overview
Problem
Existing control devices for premix gas burners are limited by imprecise air/gas ratio regulation, high head losses, excessive noise, and increased complexity, especially at high flow rates, and are prone to shutter blockages, restricting their operational range and reliability.
Innovation Solution
A device with a variable-speed fan and a second regulator that adjusts the intake duct's cross section continuously, using a shutter subject to differential pressure, to maintain constant head losses and optimize the air/gas mixture, featuring an electronic control unit and mechanical or fluid-dynamic regulation to reduce noise and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual flow rate regulator is used on the injection duct, then the air/gas ratio can be regulated before ignition, but the regulation precision is poor and the air/gas ratio deviates from ideal values
Solution Approach 1:
The patent replaces the manual mechanical flow rate regulator with an electronic control system that uses a differential pressure sensor to monitor pressure differences and an electronic control unit to automatically adjust the gas valve, achieving precise air/gas ratio control through electronic feedback rather than manual mechanical adjustment
Solution Approach 2:
The patent implements a feedback control system where a differential pressure sensor continuously monitors the pressure difference between air and gas lines, and the electronic control unit adjusts the gas valve position based on this feedback to maintain the ideal air/gas ratio dynamically
2Productivity
If the burner operates over extensive operating ranges with high flow rates, then thermal power output increases, but head losses become very high and noise becomes excessive
Solution Approach 1:
The patent uses a variable cross-section intake duct that can dynamically adjust its opening area based on operating conditions. At high flow rates, the duct opens wider to reduce flow velocity and maintain constant head losses, allowing high thermal power output without excessive energy loss or noise
Solution Approach 2:
The patent changes the geometric parameter of the intake duct (cross-sectional area) as a function of flow rate. By varying the duct opening area dynamically, the system maintains optimal flow conditions across the entire operating range, keeping head losses constant even at high thermal power outputs
3Adaptability or versatility
If multiple channels are used in the intake duct to increase operating range, then flexibility and working range improve, but constructional complexity increases
Solution Approach 1:
The patent replaces the static multi-channel structure with a dynamic single-channel system that uses a variable cross-section duct. The duct opening area changes dynamically to accommodate different flow rates, providing the same operating range flexibility as multiple fixed channels but with simpler construction
Solution Approach 2:
The patent makes a single intake duct perform multiple functions by enabling it to adapt its cross-sectional area dynamically. This universal duct replaces what would traditionally require multiple specialized channels, simplifying the construction while maintaining versatility across the operating range
4Stress or pressure
If a hinged shutter is used to control flow at low rates, then operating pressure increases for increased air speed, but the shutter is subject to blockages and requires increased maintenance
Solution Approach 1:
The patent replaces the mechanical hinged shutter system with an electronically controlled variable cross-section duct. The electronic control system adjusts the duct opening area based on differential pressure feedback, eliminating moving mechanical shutters that are prone to blockages and reducing maintenance requirements while maintaining reliable pressure control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables precise control of the air/gas ratio, reduces head losses and noise, and increases the operational range while simplifying the design and reducing maintenance, allowing for efficient operation across a wide range of thermal power and flow rates.
Implementation Method 1
The mixing system determines the negative pressure to which the air passing through is subjected to and hence the pressure in the mixing zone
Implementation Method 2
The shutter is subjected to a first pressure, applied in a position upstream of the shutter, and to a second pressure, applied in a position downstream of the shutter
Implementation Method 3
the gas flow rate is a function of the difference between the pressure at the inlet to the Venturi and the pressure in the minimum cross section of the Venturi
Data Source
AI summary
Described is a device for controlling a fuel-oxidizer mixture for a premix gas burner, comprising an intake duct, which defines a cross section for the passage of a fluid inside the duct and includes an inlet, a mixing zone and an outlet, an injection duct, connected to the intake duct in the mixing zone, a monitoring device, configured for generating a control signal, representing a combustion state in the burner, a gas regulating valve, positioned along the injection duct, a fan, positioned in the intake duct for generating therein an operating flow in an inflow direction, a control unit, configured to control the rotation speed of the fan, a regulator, coupled with the intake duct for varying the cross section. The control unit is configured for controlling the gas regulating valve in real time.