Premix Burner Flame Stabilization to Reduce Combustion Tone
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Premix combustion furnaces often experience undesirable combustion tones due to fluctuations in flue gas density and acoustical impedance, leading to unpleasant sounds that are unacceptable in residential or commercial settings.
Innovation Solution
A method of calibrating the furnace by determining specific flame stabilization periods that avoid flame detachment and combustion tone emission, involving iterative adjustments of inducer fan speeds and flame stabilization periods to maintain a balance between preventing flame detachment and minimizing combustion tone occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flame stabilization period is extended to prevent flame detachment, then flame stability is improved, but combustion tone emission increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the inducer fan speed during the flame stabilization period. The controller ramps up the fan speed from a first speed to a second speed in a controlled manner during the flame stabilization period, which prevents flame detachment while minimizing combustion tone generation. This dynamic parameter adjustment resolves the contradiction between maintaining flame stability and avoiding harmful combustion tones.
2Object-generated harmful factors
If the inducer fan speed is increased rapidly to reduce combustion tone, then combustion tone is reduced, but flame detachment occurs
Solution Approach 1:
The patent applies preliminary action by performing a purge cycle before ignition where the inducer fan operates at a high speed to clear the burner box of any accumulated fuel or gases. This preliminary high-speed operation prevents combustion tone issues during subsequent operation while ensuring safe ignition conditions, thus avoiding flame detachment during the actual combustion process.
3Object-generated harmful factors
If the flame stabilization period is shortened to reduce combustion tone, then combustion tone is minimized, but flame detachment increases
Solution Approach 1:
The patent applies dynamics by making the inducer fan speed variable rather than constant. The controller dynamically adjusts the fan speed during the flame stabilization period, ramping it up from a first speed to a second speed. This dynamic adjustment allows the system to maintain flame stability throughout the stabilization period while minimizing combustion tone generation, resolving the contradiction between short stabilization time and flame attachment.
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 method effectively reduces the likelihood of combustion tones and flame detachment by optimizing flame stabilization periods, ensuring stable operation and improved acoustic performance.
Implementation Method 1
an inducer fan that is in fluid communication with the burner box operates within a first range of fan speeds
Implementation Method 2
combusting a fuel such as natural gas. Hot flue gas from the combustion of the fuel proceeds from the burner
Implementation Method 3
The hot flue gas transfers thermal energy to the heat exchanger, from which the thermal energy is then dissipated by a flow of air
Data Source
AI summary
A method of calibrating a furnace includes determining a first flame stabilization period for the furnace that avoids detachment of a flame from a burner within a burner box of the furnace, determining a second flame stabilization period that is longer than the first flame stabilization period and avoids emission of a combustion tone from the furnace, and configuring a controller of the same or another furnace to utilize a flame stabilization period that has a duration between the first and second flame stabilization periods. Each flame stabilization period commences upon ignition of a premixed mixture of air and fuel at the burner while an inducer fan operates within a first range of fan speeds, and terminates when the rotational speed of the inducer fan increases to a second range speeds that is greater than the entire first range.