Heat Treatment of Running Metal Strip via Conduction
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Solution Overview
Problem
Conventional heat treatment processes for moving metal strips, such as annealing, suffer from high energy consumption due to inefficient heat transfer methods, particularly in continuous annealing installations, where heat recovery is limited by heat losses and the need for additional energy to circulate coolant gases.
Innovation Solution
The process employs conduction heat transfer between segments of the metal strip being heated and cooled, utilizing solid heat-conducting elements like rolls to efficiently transfer heat without significant additional energy input, maintaining moderate temperature gradients to avoid internal tensions and deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional radiant tube heating with flue gas circulation is used, then heating capability is maintained, but energy consumption increases due to heat losses and the need for additional energy to circulate gases
Solution Approach 1:
The metal strip itself serves as the heat transfer medium, using its own thermal mass and movement to transfer heat from heated segments to cooled segments. This eliminates the need for external coolant gases and their associated energy inputs, while the strip's continuous motion provides the heat transfer mechanism without requiring additional pumping or circulation energy.
Solution Approach 2:
The invention changes the heat transfer parameter from fluid-based convection (requiring gas circulation) to solid-based conduction (using the metal strip itself). By changing the state and mechanism of heat transfer, the system achieves efficient heat recovery without the energy penalties of gas circulation and heat losses through flue gases.
2Temperature
If coolant gas circulation is used for heat transfer, then heat transfer rate increases, but additional energy input is required to actuate the gas circulation
Solution Approach 1:
The metal strip's own movement through the heating and cooling zones provides the heat transfer mechanism. The strip acts as both the object being processed and the heat transfer medium, eliminating the need for separate coolant gas circulation systems and their associated energy inputs.
Solution Approach 2:
The invention replaces the mechanical gas circulation system (pumps, fans, ducts) with a thermal conduction system using the metal strip itself. The heat transfer is achieved through direct thermal contact and conduction along the strip, substituting mechanical energy input with thermal energy transfer.
3Temperature
If large temperature gradients are used for efficient heat transfer, then heat transfer efficiency improves, but internal tensions and deformations occur in the metal strip
Solution Approach 1:
The heat transfer process is divided into multiple segments along the metal strip's path. Different portions of the strip experience different temperature gradients as heat is transferred segment-by-segment from heated zones to cooled zones. This segmentation allows efficient heat transfer while distributing thermal stresses rather than concentrating them, preventing internal tensions and deformations.
Solution Approach 2:
The invention changes the temperature gradient parameter from extreme gradients (which cause stress) to moderate gradients (which are manageable). By optimizing the temperature differential across the strip segments, the system achieves sufficient heat transfer efficiency while keeping thermal stresses within acceptable limits to prevent deformation.
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 significantly reduces energy consumption by achieving efficient heat transfer while minimizing thermal shocks, resulting in lower CO2 emissions and operational costs compared to conventional methods.
Implementation Method 1
The process employs conduction heat transfer between segments of the metal strip being heated and cooled, utilizing solid heat-conducting elements like rolls to efficiently transfer heat without significant additional energy input
Implementation Method 2
the heating of the sheet is obtained by moving it past radiant tubes in which flue gases originating from the combustion of a fuel and air circulate
Implementation Method 3
flue gases originating from the combustion of a fuel and air circulate
Implementation Method 4
flue gases originating from the combustion of a fuel and air circulate
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a method for the heat treatment of a running metal strip 5, which comprises: a heating step 2a, 2b for heating the strip 5; a step 3, for cooling the heated strip 5; and conductive heat transfer from at least one segment 5b of the strip 5 which is being cooled to at least one segment 5a of the strip 5 which is being heated, so that at least part of each of said cooling 3 and heating 2a, 2b steps is carried out on the strip 5. The invention also relates to a heat transmission device 6 for implementing said method and having at least one thermally conductive solid element, such as for example a roll 13, and to a system for the heat treatment of a running metal strip 5 that incorporates such a device 6.