Flame control systems and methods for furnaces
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Solution Overview
Problem
Flame flashback in furnace systems reduces efficiency by allowing fuel to bypass combustion, leading to soot formation and incomplete combustion, particularly under low fuel input rates or high wind conditions, and existing solutions rely on complex and costly sensor feedback systems.
Innovation Solution
A flame control system that includes a controller to monitor fuel input rates and adjust both fuel input and exhaust flowrates using a modulating gas valve and draft inducer blower, respectively, to maintain robust flames outside the burner body without reliance on sensor feedback, employing an open loop control algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor feedback systems are used to control flames, then flame stability can be improved, but device complexity and cost increase
Solution Approach 1:
The system uses the existing fuel input rate information and combustion dynamics to self-regulate flame stability without external sensors. The controller monitors fuel input rate and automatically adjusts exhaust flowrate to maintain proper combustion conditions, eliminating the need for separate flame detection sensors while maintaining flame stability through self-service control.
Solution Approach 2:
The system implements feedback control using readily available operational parameters (fuel input rate, exhaust flowrate) rather than direct flame sensors. The controller continuously monitors fuel input rate and adjusts exhaust flowrate in response, creating a closed-loop control system that maintains flame stability through parameter feedback rather than visual flame detection.
2Loss of energy
If fuel input rate is reduced to match heating demand, then energy efficiency improves, but flame flashback risk increases
Solution Approach 1:
The controller proactively adjusts exhaust flowrate in response to detected fuel input rate changes before flame flashback can occur. By monitoring fuel input rate and preemptively modifying exhaust conditions, the system prevents flame flashback rather than reacting to it after the fact, allowing safe operation at reduced fuel rates that match heating demand.
Solution Approach 2:
The system changes operational parameters (exhaust flowrate) in response to fuel input rate changes to maintain safe combustion conditions. By dynamically adjusting exhaust flowrate based on fuel input rate, the system enables operation at lower fuel rates for energy efficiency while preventing flame flashback through parameter modification.
3Reliability
If exhaust flowrate is increased to prevent flame flashback, then flame stability improves, but energy loss increases
Solution Approach 1:
The system dynamically adjusts exhaust flowrate based on real-time fuel input rate conditions rather than maintaining a fixed high flowrate. The controller modifies exhaust flowrate only when and where needed to prevent flame flashback, allowing the system to operate at lower, more energy-efficient exhaust rates during normal combustion while maintaining flame stability when required.
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 approach effectively prevents flame flashback, enhances combustion efficiency by ensuring complete fuel burn, and reduces soot formation, while eliminating the need for costly sensor systems.
Implementation Method 1
a draft inducer blower operatively coupled to draw combustion air into the burners and draw combustion products through the heat exchanger via negative pressure
Implementation Method 2
a burner assembly to combust fuel with combustion air
Data Source
AI summary
A furnace includes a controller configured to instruct a blower of the furnace to increase an exhaust flowrate of the furnace, instruct a gas regulation device of the furnace to increase a fuel input rate of the furnace, or both in response to a determination that the fuel input rate is below a threshold fuel input rate for a threshold time period. In some embodiments, the controller is configured to instruct the blower to maintain an increased exhaust flowrate for a flame-stabilizing time period the gas regulation device to maintain an increased fuel input rate for the flame-stabilizing time period, or both.