Heat Treatment Furnace Zoning for Hydrogen Scale Control
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Solution Overview
Problem
The transition from fossil fuels to hydrogen-based combustion in heat treatment furnaces for steel products leads to increased scale formation and hydrogen input, affecting surface quality and processing, with potential for embrittlement and yield loss, which are not effectively managed by existing technologies.
Innovation Solution
A method involving a directly heated heat treatment furnace with separate fuel gases in different zones, using higher hydrogen content in the heating zone and conventional fuels in the equalization zone to control scale formation and hydrogen input, maintaining optimal water vapor content and minimizing oxidation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hydrogen-based fuel gas is used in the heating zone, then CO2 emissions are reduced, but scale formation and hydrogen input into the steel product increase
Solution Approach 1:
The heating zone is divided into multiple sections with different fuel gas compositions. The first section uses hydrogen-based fuel gas for decarbonization, while the second section uses fuel gas with lower hydrogen content and lower water vapor partial pressure to control scale formation and hydrogen absorption. This spatial segmentation allows simultaneous achievement of emission reduction and quality control.
Solution Approach 2:
Different sections of the heating zone are assigned different fuel gas qualities tailored to local requirements. The first section (where rapid heating occurs) receives hydrogen-rich fuel for maximum decarbonization benefit, while the second section (where steel approaches target temperature) receives fuel with controlled water vapor content to minimize oxidation and hydrogen absorption. This local optimization resolves the contradiction between emission reduction and quality protection.
2Loss of energy
If hydrogen combustion is used, then water vapor content in flue gas increases, but this accelerates oxidation and hydrogen absorption at the steel surface
Solution Approach 1:
The heating process is segmented into two stages with different atmospheric conditions. In the first section, hydrogen combustion provides rapid heating with high water vapor content acceptable because oxidation is less problematic at lower temperatures. In the second section, fuel gas composition is adjusted to reduce water vapor partial pressure, creating a less aggressive atmosphere that protects the steel surface during the critical final heating stage.
Solution Approach 2:
The steel product is pre-heated in the first section where hydrogen combustion can occur without causing excessive oxidation or hydrogen absorption. This preliminary heating stage allows the bulk of the decarbonization benefit to be realized before the steel reaches temperatures where surface quality becomes critical. The second section then provides a protective atmosphere for the final temperature approach.
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
This approach reduces adverse effects on scale formation and hydrogen absorption, improving surface quality and processing efficiency while reducing CO₂ emissions, thus enhancing the decarbonization process.
Implementation Method 1
the gas burners are supplied with at least one fuel gas for firing the heating zone and the equalization zone
Implementation Method 2
a furnace chamber of a walking beam furnace for the reheating of slabs is heated openly using 160 side-wall and ceiling radiant burners
Implementation Method 3
increased hydrogen incorporation into the steel. This is due to the increased water content in the flue gas produced during hydrogen combustion, which influences/accelerates the oxidation and absorption processes at the surface
Implementation Method 4
the increased water content in the flue gas produced during hydrogen combustion, which influences/accelerates the oxidation and absorption processes at the surface
Data Source
Figure 1
AI summary
The invention relates to a method for heat-treating a steel product in a directly heated heat treatment furnace (1), comprising at least one heating zone (2) and at least one equalization zone (3), wherein the heating zone (2) and the equalization zone (3) are equipped with gas burners, wherein the gas burners are supplied with at least one fuel gas for firing the heating zone (2) and the equalization zone (3), wherein the steel product is first heated to a target temperature (Tz) in the heating zone (2) and subsequently maintained at a target temperature (Tz) in the equalization zone (3), wherein at least in a subsection (2.1) of the heating zone (2) a fuel gas is used which differs from the fuel gas in the equalization zone (3).