Divided Hot Strip Mill Layout for Thin Strip Temperature Control
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Solution Overview
Problem
Conventional Hot Strip Mills face challenges in producing high-quality thin steel strips due to excessive gas consumption, environmental emissions, and limited production flexibility, which affects the ability to maintain the desired temperature and quality of the final product.
Innovation Solution
The proposed solution involves a new generation Hot Strip Mill plant with a divided finishing rolling train, including pre-finishing and finishing stands, and a rapid heating device interposed between these stands to maintain the austenitic range of steel without phase transformations, thereby ensuring high-quality thin strips can be produced efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gas heating furnaces are used to heat thick slabs to high temperatures, then the required temperature of at least 830°C at the outlet of the last finishing stand is achieved, but gas consumption and environmental emissions increase significantly
Solution Approach 1:
The finishing rolling train is divided into pre-finishing stands and finishing stands, with a rapid heating device interposed between them. This segmentation allows the heating process to be localized and optimized, reducing the overall gas consumption required while maintaining the necessary outlet temperature.
Solution Approach 2:
The rapid heating device performs preliminary heating of the strip between the pre-finishing and finishing stands, ensuring the strip reaches the required temperature before entering the finishing stands. This preliminary action reduces the need for excessive heating throughout the entire process, thereby lowering gas consumption.
2Temperature
If gas heating furnaces heat slabs to higher temperatures for particular steels, then thermal targets are met, but production flexibility is reduced due to the need to wait for furnace heating
Solution Approach 1:
The rapid heating device provides preliminary and rapid heating capability that can be quickly adjusted for different steel types and thermal targets, eliminating the need to wait for the entire furnace to reach the desired temperature. This enables greater production flexibility and faster response to different product requirements.
Solution Approach 2:
The heating system becomes dynamic and adaptable through the rapid heating device, which can be selectively activated and adjusted based on the specific steel type and required thermal target, allowing the plant to respond flexibly to different production demands without reconfiguring the entire furnace system.
3Speed
If the maximum speed of the strip exiting the finishing train is limited to prevent aerodynamic effects, then safety is maintained, but the ability to produce thin strips with the desired temperature is compromised
Solution Approach 1:
The rapid heating device performs preliminary heating of the strip between pre-finishing and finishing stands, compensating for the temperature drop that would otherwise occur at limited speeds. This allows thin strips to be produced at controlled speeds while still achieving the required outlet temperature of at least 830°C.
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 configuration allows for the production of high-quality steel strips with thicknesses as low as 0.9 mm without compromising productivity, reducing gas consumption and emissions, and enhancing production flexibility, enabling uniform mechanical and geometric properties along the entire coil length.
Implementation Method 1
a rapid heating device consisting of selectively activatable elements interposed between the at least one pre-finishing stand and the plurality of finishing stands so as to heat the pre-finished rolled product
Data Source
AI summary
A plant and a method for producing a final strip starting from a slab having a determinate starting thickness, including: at least one heating furnace configured to heat at least the slab to a determinate starting temperature; at least one reversible roughing stand configured to subject the slab to one or more rolling passes in order to obtain an intermediate rolled product; and a continuous rolling train disposed operatively in line with the roughing stand and configured to reduce the thickness of the intermediate rolled product, until the final strip having a determinate final thickness is obtained.