Lime Kiln Flame Imaging for Real-Time Burner Control

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Solution Overview

Problem

Existing methods for controlling the lime kiln process in the caustisizing process are inadequate for real-time adjustment, leading to potential damage from excessive or insufficient fuel use and faulty air delivery, affecting the calcining reaction and the production of white liquor.

Innovation Solution

A method and system for monitoring the flame of a lime kiln burner using image processing and a pretrained algorithm to identify areas of interest, calculate relevant quantities, and adjust fuel and air delivery based on predetermined thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If sampling and measuring remaining calcium carbonate is used to control the caustisizing process, then the process can be monitored, but real-time adjustment is not achieved leading to potential damage from excessive or insufficient fuel use

Engineering Contradiction:
Improveprocess control reliabilityVSAvoidresponse time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical sampling and measurement system with an optical imaging system using a camera to capture flame images. This substitution enables continuous real-time monitoring of the burning process through image analysis, eliminating the time delay inherent in periodic sampling while maintaining reliable process control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces image processing algorithms as an intermediary between the physical flame state and the control system. The algorithms extract meaningful parameters from flame images, serving as a bridge that translates visual information into actionable control signals for real-time adjustment of fuel and air delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If more fuel is used in the burner to ensure adequate calcining reaction, then the calcining reaction is sufficient, but the temperature might rise too high causing calcium particles to melt and lining damage

Engineering Contradiction:
Improvecalcining reaction completenessVSAvoidoverheating damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback control system where flame images are continuously analyzed to determine burning quality parameters. Based on this feedback, the control system automatically adjusts fuel and air delivery to maintain optimal combustion conditions, preventing both incomplete calcining and excessive temperature rise that would cause damage.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent dynamically changes combustion parameters (fuel flow rate, air delivery) based on real-time flame analysis. By adjusting these parameters according to the actual burning state detected through image processing, the system maintains the calcining reaction completeness while preventing temperature from rising too high and causing damage.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If insufficient fuel is used to prevent overheating, then temperature control is maintained, but a large part of lime mud remains unreacted resulting in inadequate caustisizing process

Engineering Contradiction:
Improvetemperature controlVSAvoidcaustisizing process quality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The feedback control system continuously monitors flame characteristics through image analysis and adjusts fuel delivery accordingly. When the flame indicates insufficient burning, the system increases fuel supply to ensure complete calcining reaction, while when overheating is detected, it reduces fuel supply, thus maintaining both temperature control and process quality.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts fuel and air parameters based on real-time flame analysis. By changing these parameters in response to detected burning conditions, the system ensures adequate fuel supply for complete reaction when needed while preventing excessive temperature rise, thereby maintaining both temperature control and caustisizing process quality.

Inventive Principle:
Principle #35Parameter changes

4Loss of information

If traditional imaging methods are used for monitoring the burning process, then flame visualization is achieved, but real-time control capability is not provided

Engineering Contradiction:
Improveburning process informationVSAvoidcontrol capability
Core Design Contradiction:
Loss of informationVSEase of operation

Solution Approach 1:

The patent introduces automated image processing algorithms as an intermediary that extracts quantitative burning parameters from flame images. This intermediary layer transforms visual information into actionable data that directly controls the burner, providing both comprehensive process information and automated control capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system establishes a feedback loop where flame images are continuously analyzed and the results automatically control fuel and air delivery. This feedback mechanism converts the imaging system from a passive monitoring tool into an active control system that provides real-time adjustment capability.

Inventive Principle:
Principle #23Feedback

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

Enables rapid response to process disturbances, stabilizes the burning process, ensures balanced production of white liquor, and promotes a more environmentally friendly operation.

Implementation Method 1

imaging a video stream showing the burner end of the lime kiln

Methodology Applied
Scientific EffectElectromagnetic radiation detection: Light

Data Source

PatentEP4275183B1Method and system for flame monitoring and control
Publication Date: 2026.03.18 ANDRITZ OY
  • EP4275183B1 patent drawingFigure 1
  • EP4275183B1 patent drawingFigure 2
  • EP4275183B1 patent drawingFigure 3

AI summary

A method for monitoring a flame of a burner of a lime kiln, comprising imaging a video stream showing the burner end of the lime kiln; extracting at least one image from the imaged video stream; determining, using a pretrained algorithm, from the at least one image at least one area of interest, wherein the at least one area of interest comprises a part of the at least one image showing an area comprising at least one characteristic portion of the flame and/or burner end; calculating the area of the at least one characteristic portion based on the pixels of the at least one area of interest; and determining at least one quantity of interest based on the calculated area of the at least one characteristic portion.