Gas Boiler Flame Diffuser Segmentation for Stable Low-Flow Combustion
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Solution Overview
Problem
Existing gas-fired boilers with variable modulation ratios face difficulties in maintaining stable air/gas mixing at low flowrates, leading to unstable combustion and increased pollutant emissions, particularly when operating at reduced fan speeds or with radiating burners.
Innovation Solution
The boiler incorporates two physically separated flame diffuser elements with a clapet valve in the feeding duct, allowing for independent control of the air/gas mix and enabling modulation of heating power by activating either or both diffuser elements, with a single fan and gas valve system, and includes an auxiliary diffuser element to stabilize the flame and reduce thermoacoustic issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fan operates at reduced speeds to allow modulation at low flowrates, then energy consumption is reduced, but the air/gas mixing becomes unstable and combustion reliability deteriorates
Solution Approach 1:
The burner is divided into two physically separated flame diffuser elements: a primary diffuser for main combustion and a secondary diffuser for stabilization. This segmentation allows the secondary diffuser to maintain stable combustion at low fan speeds while the primary diffuser handles the modulation, resolving the contradiction between reduced energy consumption and maintained combustion reliability.
2Device complexity
If a single feeding duct is used to simplify the system, then device complexity is reduced, but control precision over air/gas mix at low flowrates deteriorates
Solution Approach 1:
While maintaining a single feeding duct structure, the system segments the flame generation into two separate diffuser elements with distinct functions. The secondary diffuser is specifically designed to stabilize the air/gas mix at low flowrates, achieving precise control without requiring multiple feeding ducts, thus resolving the contradiction between simplicity and control precision.
3Productivity
If the burner operates in radiating phase with flame close to surface, then heating efficiency is improved, but flame signal detection becomes unstable and control precision deteriorates
Solution Approach 1:
The secondary flame diffuser acts as an intermediary element that stabilizes the flame and provides a consistent reference signal for detection. Even when the primary burner operates in radiating phase with reduced signal, the secondary diffuser maintains a stable flame that can be reliably detected, resolving the contradiction between heating efficiency and measurement precision.
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
This configuration achieves stable combustion and reduced pollutant emissions across a wide range of thermal demands, simplifies ignition, and prevents explosion phenomena by allowing precise control of the air/gas mix and flowrate, enhancing the boiler's modulation ratio and operational efficiency.
Implementation Method 1
The fan generates an air flowrate with a pressure related to the revolutions per minute of the fan itself
Implementation Method 2
The presence of a clapet valve, which is suitable for opening and closing the feeding duct
Implementation Method 3
a burner (having, for instance, a plane or cylindrical shape) having a diffuser element whereon a flame is generated
Implementation Method 4
Such shortcomings can be overcome by using special components (for instance a double Venturi mixer or a fan capable of operating at low revolutions per minute)
Data Source
AI summary
A gas-fired boiler comprises at least one burner (1) and feeding means (4) for feeding a fluid to such burner (1), said feeding means (4) being connected to a fan (5), a gas duct (7) being provided to feed gas to said fan (5). The burner comprises at least a first main flame-diffuser element (25) and a second auxiliary flame-diffuser element (26, the feeding means being a feeder duct (4) connected to the main diffuser element (25) and to the fan (5), said fluid comprising air or a mix of air and gas which is sent in such feeder duct (4), a tubular body (17) connected to the auxiliary diffuser element (26) opening in said duct (4), a gas carrying pipe (10) opening directly in such tubular body (17).