Hot Metal Desulfurization via SO2 Fluorescence Analysis

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Solution Overview

Problem

Conventional methods for analyzing sulfur concentration in hot metal are time-consuming and lack accuracy, leading to variations in desulfurization effectiveness, increased desulfurization agent usage, and disruptions in steel-making processes.

Innovation Solution

A method involving high-frequency induction heating in a pure oxygen atmosphere to convert sulfur in hot metal to SO2, followed by ultraviolet fluorescence analysis of SO2-containing gases for precise sulfur concentration measurement, allowing for real-time adjustment of desulfurization conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods (X-ray fluorescence, emission spectrophotometry, infrared absorption) are used to analyze S concentration in hot metal, then the analysis can be conducted, but the analysis time is too long (about 15 minutes) and accuracy is insufficient for ppm-level control

Engineering Contradiction:
ImproveS concentration measurement accuracyVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces conventional mechanical/chemical analysis methods (X-ray fluorescence, emission spectrophotometry, infrared absorption) with a chemical combustion method followed by gas chromatography detection. The sample is combusted in a stream of oxygen gas, and S is converted to SO2 which is then detected by gas chromatography with a pulsed discharge detector, achieving both rapid analysis (within minutes) and high accuracy for ppm-level S concentration control

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

Solution Approach 2:

The patent changes the detection parameter from direct solid/liquid sample analysis to gas phase SO2 detection. By combusting the sample in oxygen to convert S to SO2 gas, and then detecting the SO2 concentration via gas chromatography, the method achieves faster analysis time and higher precision for low S concentrations compared to conventional methods

Inventive Principle:
Principle #35Parameter changes

2Reliability

If excessive desulfurization agent is added to avoid S concentration faults, then the on-target ratio improves, but the production cost increases

Engineering Contradiction:
Improveon-target ratio of S concentrationVSAvoiddesulfurization agent usage
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent implements a feedback control system where S concentration is rapidly and accurately measured during desulfurization treatment using the gas chromatography method. The measured S concentration values are fed back to control the desulfurization process, allowing precise termination of treatment when target S concentration is achieved, thereby improving on-target ratio and avoiding excessive desulfurization agent addition

Inventive Principle:
Principle #23Feedback

3Measurement precision

If S concentration analysis is delayed until after desulfurization treatment, then the analysis can be completed, but step disruption occurs in subsequent steel-making process

Engineering Contradiction:
ImproveS concentration analysis completionVSAvoidsteel-making process continuity
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent performs S concentration analysis at multiple stages including before, during, and after desulfurization treatment using the rapid gas chromatography method. By conducting preliminary and intermediate analysis, the system can determine whether additional desulfurization is needed before proceeding to steel-making, preventing delays and maintaining process continuity

Inventive Principle:
Principle #10Preliminary action

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 and accurate sulfur concentration analysis, improving the on-target ratio of desulfurization, reducing excessive desulfurization agent usage, and minimizing process disruptions in steel production.

Implementation Method 1

a high frequency induction heating step of oxidizing the sample under a high frequency induction heating in a pure oxygen atmosphere

Methodology Applied
Scientific EffectHigh frequency induction heating: Electromagnetic Induction

Implementation Method 2

oxidizing the sample under a high frequency induction heating in a pure oxygen atmosphere so as to render an oxygen concentration in SO2-containing gas produced by combustion of the sample

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 3

an analysis step of analyzing SO2-containing gas generated in the high frequency induction heating step through an ultraviolet fluorescence method to quantify S concentration in the sample

Methodology Applied
Scientific EffectUltraviolet fluorescence: Fluorescence

Data Source

PatentEP2743683B8Method for desulfurizing hot metal
Publication Date: 2015.12.16 JFE STEEL CORP

AI summary

In a method for desulfurizing hot metal by analyzing S concentration of a sample taken out from the hot metal in at least one stage before, during and after desulfurization treatment of the hot metal, and conducting further subsequent desulfurization or judging an end of desulfurization or determining subsequent desulfurization conditions based on an analyzed value of S concentration, the S concentration is analyzed rapidly and precisely by a method comprising a high frequency induction heating step of oxidizing the sample under a high frequency induction heating in a pure oxygen atmosphere to convert S in the hot metal to SO2 and an analysis step of analyzing SO2-containing gas generated in the high frequency induction heating step through an ultraviolet fluorescence method to quantify S concentration in the sample, whereby S concentration after the desulfurization is controlled precisely and hence fault of S concentration is prevented but also the increase of the cost due to the excessive addition of a desulfurization agent and step disruption at steel-making step are prevented.