Blast Furnace Solidified Layer Detection Using Pig Iron Heat Balance

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Solution Overview

Problem

Existing methods for detecting solidified layer fluctuation in blast furnaces are unable to detect fluctuations at an early stage due to reliance on steady-state heat transfer calculations and cannot distinguish between newly generated pig iron and melted solidified material, leading to potential tuyere erosion and unstable operations.

Innovation Solution

A method that utilizes the amount of heat supplied to the lower part of the blast furnace and the temperature of tapped pig iron to determine solidified layer fluctuations using expressions (1) and (2), allowing for early detection and adjustment of solidified layer growth or decrease.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If heat transfer calculation is used to estimate solidified layer thickness, then the thickness can be estimated, but the fluctuation cannot be detected at an early stage

Engineering Contradiction:

Improvesolidified layer thickness estimationVSAvoiddetection timing

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by monitoring heat supply amount and pig iron temperature from the beginning of the process to detect solidified layer fluctuation before it completes. Instead of waiting for steady-state heat transfer to establish, the system continuously compares actual heat supply with theoretical values to identify fluctuations in advance, enabling early intervention before the fluctuation becomes significant.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If thermometers are arranged at bottom bricks to measure temperature, then temperature data can be obtained, but the fluctuation detection is delayed until steady state is reached

Engineering Contradiction:

Improvetemperature measurementVSAvoidfluctuation detection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent uses pig iron temperature as an intermediary parameter to detect solidified layer fluctuation. Instead of directly measuring the solidified layer thickness or relying solely on bottom brick temperatures, the system monitors the temperature of pig iron which reflects the thermal state of the entire system, including the solidified layer, providing earlier and more reliable fluctuation detection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If pig iron amount is monitored to detect solidified layer changes, then the amount can be estimated, but newly generated pig iron cannot be separated from melted solidified material

Engineering Contradiction:

Improvepig iron amountVSAvoidsolidified layer fluctuation detection

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by using multiple parameters (heat supply amount, pig iron temperature, and their relationship) instead of relying solely on pig iron amount. By analyzing the correlation between heat supply and temperature, the system can distinguish between pig iron generated from charging and pig iron from melted solidified layer, enabling precise fluctuation detection.

Inventive Principle:

Principle #35Parameter changes

4Strength

If solidified layer grows excessively, then bottom brick wear is suppressed, but the capacity for storing molten pig iron decreases

Engineering Contradiction:

Improvebottom brick wear resistanceVSAvoidpig iron storage capacity

Core Design Contradiction:

StrengthVSVolume of stationary object

Solution Approach 1:

The patent implements feedback control by continuously monitoring heat supply amount and pig iron temperature to detect solidified layer fluctuation, then using this information to control heat supply adjustments. When the solidified layer approaches excessive thickness, the system reduces heat supply to prevent further growth, thereby maintaining bottom brick protection while preserving adequate storage capacity.

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 early detection of solidified layer fluctuations, promoting appropriate operations to stabilize the blast furnace by either melting or growing the layer as needed, thereby preventing tuyere erosion and maintaining stable operation.

Implementation Method 1

the heat transfer calculation is based on the assumption of steady-state heat transfer in the solidified layer and the bottom bricks of the blast furnace

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

using the amount of heat supplied to pig iron in the lower part of the blast furnace and the amount of heat in the pig iron tapped

Methodology Applied

Scientific EffectThermal energy: Heating

Data Source

PatentUS12540363B2Method for detecting fluctuation of solidified layer and method for operating blast furnace

Publication Date: 2026.02.03 JFE STEEL CORP

AI summary

A method for detecting a fluctuation of a solidified layer, and a method for operating a blast furnace by employing the relevant method. In the method for detecting a fluctuation of a solidified layer, the fluctuation of the solidified layer in the lower part of a blast furnace is detected by using the amount of heat supplied to pig iron in the lower part of the blast furnace and the amount of heat in the pig iron tapped in a predetermined period.