Combustion Device Control Using Predictive Sensor Delay Compensation
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Solution Overview
Problem
Combustion sensors in combustion devices exhibit delayed responses due to factors like sensor positioning, current modulation levels, and device size, leading to inadequate control and regulation, potentially causing unfavorable combustion conditions and emissions, especially during rapid process changes.
Innovation Solution
A control and regulation system that recalculates setpoints based on sensor signals, uses analog-to-digital converters, and directly intervenes in actuators to adjust combustion air ratio and oxygen content, minimizing delay and ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a combustion sensor is positioned in the flue gas duct to measure combustion parameters, then the sensor can detect combustion air ratio and oxygen content, but the sensor signal reacts with a delay of several tens of seconds or even more than a minute, making the control and regulation too slow to prevent critical combustion conditions
Solution Approach 1:
The system determines a preliminary response time characteristic for the combustion sensor before actual combustion occurs. Based on this predetermined response time, the control system calculates and issues control signals in advance to adjust combustion air supply, ensuring that control actions are taken before the sensor would otherwise detect changes with delay. This prevents critical combustion conditions by acting proactively rather than reactively.
2Reliability
If the combustion sensor signal is used for control and regulation, then the combustion air ratio can be determined, but the dead time causes the control intervention to be too slow, allowing unfavorable combustion conditions to develop and potentially causing flame extinction or unburned fuel escape
Solution Approach 1:
The control system determines a response time characteristic of the combustion sensor in advance and uses this information to issue control signals proactively. By calculating the expected sensor response delay, the system adjusts combustion air supply before unfavorable conditions develop, maintaining reliable combustion control without waiting for delayed sensor feedback.
Solution Approach 2:
The system continuously monitors the combustion sensor signal and compares it with expected values. When deviations indicate potential unfavorable combustion conditions, the control system adjusts combustion air supply in real-time based on the predetermined response time characteristic, creating a closed-loop feedback mechanism that compensates for sensor delay.
3Speed
If modulation curves of air or fuel actuators are adjusted to respond to combustion changes, then control responsiveness can be improved, but improperly adjusted modulation curves can lead to rapid changes in the combustion process that exceed control system intervention capability
Solution Approach 1:
The system determines modulation curves for air or fuel actuators in advance, before rapid combustion changes occur. These predetermined modulation curves are optimized to provide appropriate control response while maintaining combustion stability, avoiding the pitfalls of both overly aggressive and overly conservative control adjustments.
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 system effectively prevents critical emissions by quickly adapting to combustion changes, maintaining stable operation and avoiding oscillations, thus enhancing the responsiveness and reliability of combustion devices.
Implementation Method 1
the combustion air ratio and/or the air ratio λ can be determined using an ionization current through an ionization electrode
Implementation Method 2
An alternating voltage is first applied to the combustion sensor, in particular to the ionization electrode. Due to the rectifying effect of a flame, an ionization current flows as a direct current in only one direction.
Data Source
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AI summary
Control and/or regulation of a combustion device. Device (12) for controlling and/or regulating a combustion device (1), the control and/or regulation device (12) comprising a memory comprising at least one lower or upper limit value and at least one factor, wherein the device (12) is communicatively connectable to a sensor (18) and to a first actuator (3, 4, 9) and is configured to: receive a first input signal from the sensor (18); process the first input signal into a first measured value, which indicates a combustion air ratio and/or an air number λ and/or an oxygen content; load the lower or upper limit value from the memory and compare the first measured value with the at least one lower or upper limit value;If the first measured value falls below or exceeds at least one limit value: calculate a correction value as a function of the measured value of at least one factor; generate a first output signal as a function of the correction value and send it to the first actuator (3, 4, 9).