Premix Gas Burner Air/Gas Mixer with Segmented Venturi Channels
Solution Overview
Problem
Existing premix burners face suboptimal reduction of deleterious effects due to offset variations in gas valves, particularly at low thermal power rates, leading to variations in air/gas ratios.
Innovation Solution
Incorporating a venturi channel type air/gas mixer with a localized pressure loss device and a flow divider split into two channels, each with a plug that adjusts to maintain a constant air/gas ratio through pressure differences and a secondary plug to mitigate offset effects, along with an electronic control unit to manage fan and gas valve operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional gas valve with offset variation is used, then the burner can operate across a wide modulation range, but the air/gas ratio becomes unstable at low thermal power rates due to offset variations
Solution Approach 1:
The venturi channel is divided into two separate channels (first venturi channel and second venturi channel) instead of using a single channel. Each channel has its own nozzle and plug arrangement, allowing independent control and stabilization of gas flow at different operating conditions, particularly at low thermal power rates where offset variations occur.
Solution Approach 2:
A common gas circuit is introduced as an intermediary element connecting the two venturi channels. This common gas circuit allows pressure equalization and stabilizes the gas supply to both channels, ensuring that offset variations in the gas valve do not cause unstable air/gas ratios in either channel.
2Duration of action of stationary object
If offset variations occur in the gas valve during long working time, then the burner maintains operation, but deleterious effects increase particularly at minimum thermal power
Solution Approach 1:
By segmenting the venturi channel into two independent channels with separate nozzle-plug assemblies, the system can compensate for offset variations that occur during long operating periods. Each channel maintains its own stable air/gas ratio independently, preventing the accumulation of deleterious effects at minimum thermal power settings.
Solution Approach 2:
The system changes the pressure distribution parameters by introducing a common gas circuit that equalizes pressure between the two venturi channels. This parameter change ensures that even when offset variations occur during prolonged operation, the air/gas ratio remains stable and combustion efficiency is maintained across the entire operating range.
3Device complexity
If a single venturi channel is used, then the device structure is simple, but the air/gas ratio cannot be maintained constant across different thermal power rates
Solution Approach 1:
The single venturi channel is segmented into two parallel channels, each capable of operating independently to provide stable air/gas mixing at different thermal power rates. This segmentation allows the system to maintain constant air/gas ratio across the full modulation range while adding only moderate structural complexity.
Solution Approach 2:
The common gas circuit serves multiple functions: it connects the two venturi channels, equalizes pressure between them, and stabilizes the gas supply. This multi-functionality allows the system to maintain constant air/gas ratio across different operating conditions without requiring separate control mechanisms for each channel.
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
Significantly reduces the negative effects of offset variations across the entire working range, especially at low power rates, ensuring a consistent air/gas ratio and improved combustion efficiency.
Implementation Method 1
a venturi channel type air/gas mixer (11) placed downstream of a fan (12) with respect to an air flow (AF)... Each gas inlet point in the localized pressure drop device (11A) is equipped, respectively, with a respective nozzle (UG1), (UG2)... the pressure difference existing between an output pressure P2 of the gas valve (14) and a pressure P3 existing in the narrowest point of the venturi channel type air/gas mixer (11)
Implementation Method 2
a venturi channel type air/gas mixer (11) placed downstream of a fan (12) with respect to an air flow (AF)... the venturi channel type air/gas mixer consisting of a localized pressure loss device (11A)
Implementation Method 3
the amount of gas released by the gas valve (14) towards the mixer (11) is correlated to the pressure difference existing between an output pressure P2 of the gas valve (14) and a pressure P3 existing in the narrowest point of the venturi channel type air/gas mixer (11)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An air/gas premix burner (10) comprising: a fan (12) for sending the air/gas mixture towards a combustion head (TC); - a gas valve (14) for regulating the introduction of combustible gas; - an air/gas mixer (11) which comprises a localized pressure loss device (11A); and - a combustion head (TC). The air/gas mixer (11) comprises two channels (CHI, CH2), only one of the channels being provided with two hinged flaps designed to open and close for regulating the flow rate of the mixture.