Reheating Furnace Scale Control Using Infrared Surface Imaging

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Solution Overview

Problem

Existing reheating furnace systems lack a robust, real-time control mechanism to accurately measure and reduce primary scale formation, leading to significant economic losses and inefficiencies due to non-adherent scale falling into the furnace, which is not addressed by current numerical models or traditional measurement methods.

Innovation Solution

A system utilizing infrared cameras and optical sensors to measure adherent and non-adherent scale on the product surface, combined with digital processing to determine loss on ignition, and adjust furnace parameters in real-time to minimize scale formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If local fuels (COG, BFG) are used instead of natural gas, then operating costs are reduced, but scale formation increases due to lower calorific value and higher impurity content

Engineering Contradiction:
Improveoperating costsVSAvoidscale formation
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

The patent implements a feedback control system that continuously monitors scale formation on the product surface using optical sensors and infrared cameras. The system measures the amount of scale in real-time and adjusts furnace operating parameters (temperature, atmosphere composition, heating rate) dynamically to minimize scale formation while maintaining production efficiency with local fuels

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention changes key process parameters including oxygen potential, temperature profiles, and heating rates based on real-time scale formation measurements. By adjusting these parameters dynamically, the system optimizes the balance between using cost-effective local fuels and minimizing scale formation that results from fuel impurities

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If traditional numerical models are used to predict scale formation, then scale prediction is possible under stable conditions, but accuracy deteriorates when furnace operation varies or fuel quality changes

Engineering Contradiction:
Improvescale prediction accuracyVSAvoidmodel adaptability to varying conditions
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system uses real-time optical measurements of scale formation as feedback to continuously validate and adjust predictive models. This closed-loop approach allows the system to maintain accurate scale predictions even when furnace operating conditions or fuel quality vary, as the model is constantly refined based on actual measurements

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-calibration and self-optimization by comparing predicted scale formation with actual measurements from optical sensors. The model automatically adjusts its parameters based on this comparison, enabling it to adapt to changing conditions without external intervention and maintain high prediction accuracy

Inventive Principle:
Principle #25Self-service

3Ease of operation

If scale formation is not monitored and controlled, then furnace operation is simple, but economic losses increase due to scale falling into the furnace and material waste

Engineering Contradiction:
Improvefurnace operation simplicityVSAvoidmaterial loss from scale
Core Design Contradiction:
Ease of operationVSLoss of substance

Solution Approach 1:

The system implements self-monitoring and self-control of scale formation through automated optical sensing and real-time parameter adjustment. Once installed, the system operates autonomously, continuously measuring scale formation and adjusting furnace parameters without requiring manual intervention, thus maintaining operational simplicity while dramatically reducing material losses

Inventive Principle:
Principle #25Self-service

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 provides precise, real-time control over scale formation, optimizing furnace operation to reduce economic losses and environmental impact by minimizing scale formation and improving operational efficiency.

Implementation Method 1

a device for acquiring images of a portion of the upper surface of a product exiting an oven in the infrared spectrum using an infrared camera

Methodology Applied
Scientific EffectInfrared radiation detection: Infrared Radiation

Implementation Method 2

at least two optical sensors, one placed upstream of the descaling machine and the other downstream, which make it possible to determine the height of the product

Methodology Applied
Scientific EffectOptical measurement: Light

Implementation Method 3

The fumes are extracted from the furnace by a suction system, via a heat recovery unit that preheats the combustion air supplying the burners

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 4

The hot fumes react with the surface of the product being heated in the furnace, resulting in the formation of surface layers of oxides

Methodology Applied
Scientific EffectOxidation: Oxidation

Data Source

PatentEP4051975B1Device and method for controlling a reheating furnace
Publication Date: 2025.12.17 FIVES STEIN SA
  • EP4051975B1 patent drawingFigure 1~3D
  • EP4051975B1 patent drawingFigure 4~5
  • EP4051975B1 patent drawingFigure 6.1~6.3

AI summary

Method for controlling a furnace (4) for reheating steel products (5), comprising: forming an infrared image, using an infrared camera (20), of an upper face of a product (5) over the width and at least partially over the length thereof when the product is arranged on a predetermined furnace discharging surface; digital processing, comprising binarisation of the infrared image into two classes of pixels: one class of pixels which corresponds to the pixels associated with a presence of calamine bonded to the face of the product and another class of pixels which corresponds to the pixels associated with a presence of calamine which is not bonded to the face of the product; establishing the quantities of non-bonded calamine and calamine bonded to the upper face of the product from the binarised image; modifying control parameters for the furnace from the established quantities of non-bonded and bonded calamine.