Gas Burner Ignition Control for Lean Hydrogen-Air Mixtures
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Solution Overview
Problem
Existing heating boilers experience misfires during ignition, particularly when using hydrogen as fuel gas, due to the difficulty in maintaining a safe and lean fuel gas-air mixture with high flame speeds and short ignition delay times.
Innovation Solution
A method involving a control valve with an actuator and throttle element for closed-loop control of fuel gas flow, combined with a plausibility test and termination conditions to ensure a safe and lean ignition, including a differential pressure sensor to monitor pressure differences and an ignition sensor to detect flame formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydrogen is used as fuel gas to improve energy efficiency, then combustion efficiency is improved, but misfires occur during ignition due to high flame speeds and short ignition delay times
Solution Approach 1:
The control valve is moved to a reference position before ignition to pre-establish a safe minimum fuel gas flow rate. This preliminary action ensures that the fuel gas-air mixture is guaranteed to be lean enough to prevent misfires, addressing the reliability issue while maintaining hydrogen's combustion efficiency benefits
Solution Approach 2:
A plausibility test is performed to verify the control valve position and fuel gas flow rate before ignition. The differential pressure sensor provides feedback on the actual flow conditions, allowing the system to confirm the mixture is within safe lean limits before attempting ignition, thereby improving ignition reliability with hydrogen
2Reliability
If the fuel gas flow rate is increased to ensure ignitable mixture, then ignition reliability is improved, but the mixture may become too rich causing misfires
Solution Approach 1:
The control valve is positioned at a reference position that preemptively limits the fuel gas flow rate to a minimum safe level before ignition. This preliminary anti-action counteracts the tendency for the mixture to become too rich, preventing misfires while still ensuring ignitability
Solution Approach 2:
The system changes the flow rate parameter dynamically by moving the control valve to a reference position that establishes a minimum flow rate. This parameter adjustment ensures the mixture remains within the lean可燃 range, avoiding both misfires from rich mixtures and failure to ignite from lean mixtures
3Reliability
If a plausibility test is performed to verify control valve position, then safety is improved, but the ignition process time is increased
Solution Approach 1:
The plausibility test performs only the essential verification of control valve position and minimum flow rate conditions rather than a complete system check. This partial action provides sufficient safety verification for lean ignition while minimizing the time added to the ignition process
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
Ensures reliable and safe ignition of the fuel gas-air mixture by preventing misfires and ensuring the mixture remains within safe combustion limits, even with fuels like hydrogen, by minimizing the risk of excessively rich mixtures.
Implementation Method 1
a differential pressure sensor (8) is provided, which is designed to acquire a pressure difference, referred to as offset pressure, between a measuring site (p2) along the fuel gas flow path and a measuring site (p1, p0) along the air flow path
Implementation Method 2
An ignition device (7) is provided for igniting the fuel gas-air mixture on the gas burner (6)
Data Source
AI summary
A method for the failsafe and lean ignition of a fuel gas-air mixture on a gas burner (6), which is mixed in a mixing device (4) arranged upstream of the gas burner (6). A control valve (2) along the fuel gas flow path has an actuator (21) and a throttle element (23), moved by the actuator (21), for the closed-loop control of a flow rate of the fuel gas flowing into the mixing device (4). A test is performed to determine whether the throttle element (23) is in the throttle reference position when the actuator (21) is in the actuator reference position. The throttle element (23) is moved in a flow rate-increasing manner starting at a start time (tD). The flow rate-increasing movement of the throttle element (23) is stopped as soon as at least one of multiple predetermined termination conditions occurs.