Dry Wet Cooling Section for Steel Strip Annealing Lines
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Solution Overview
Problem
Current cooling sections in continuous annealing or galvanizing lines lack flexibility to achieve high cooling rates required for producing steels with superior mechanical and metallurgical properties, and they often require intermediate chemical treatments for galvanization.
Innovation Solution
A cooling section combining dry and wet cooling zones, where the dry zone uses a gas mixture like nitrogen and hydrogen, and the wet zone uses liquid or a mixture of gas and liquid, allowing for adjustable cooling rates up to 1000°C/s without intermediate chemical treatments, and enabling simultaneous or sequential operation of both zones without cutting the strip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas cooling with nitrogen and hydrogen mixture is used, then the steel strip does not oxidize and galvanizing is possible without further chemical treatment, but the cooling rate is limited to around 200°C/s which is not suitable for producing steels with high mechanical properties requiring higher cooling rates
Solution Approach 1:
The patent combines dry cooling (gas cooling with N2/H2 mixture) and wet cooling (water spray cooling) into a single integrated cooling section. The dry cooling zone provides non-oxidizing conditions, while the wet cooling zone enables high cooling rates up to 1000°C/s. Both zones operate simultaneously or sequentially on different portions of the steel strip to achieve both non-oxidizing conditions and high cooling rates.
Solution Approach 2:
The cooling section is divided into distinct dry cooling zones and wet cooling zones that can operate independently or in combination. This segmentation allows different cooling methods to be applied to different areas or at different stages of the cooling process, enabling the system to achieve both non-oxidizing conditions and high cooling rates as needed.
2Speed
If wet cooling is used to achieve high cooling rates of around 1000°C/s, then steels with high mechanical properties can be produced, but the steel strip requires intermediate chemical treatment before galvanizing due to oxidation
Solution Approach 1:
The patent merges dry cooling and wet cooling zones within the same continuous processing line. The dry cooling zone with nitrogen-hydrogen mixture prevents oxidation, while the wet cooling zone provides high cooling rates. By combining these zones, the system achieves both high cooling rates and non-oxidizing conditions, eliminating the need for intermediate chemical treatments before galvanizing.
3Manufacturing precision
If a cooling section is designed for high cooling rates, then steels with superior mechanical and metallurgical properties can be produced, but the section lacks flexibility to produce different types of steel with varying cooling rate requirements
Solution Approach 1:
The cooling section incorporates adjustable parameters including variable cooling rates, selectable operating modes (dry cooling only, wet cooling only, or combined), and controllable temperature profiles. This dynamic adjustability allows the same cooling section to produce different steel types with varying mechanical properties by modifying operational parameters rather than requiring different dedicated cooling sections.
Solution Approach 2:
The integrated cooling section serves multiple functions: it can operate as a dry cooling zone, a wet cooling zone, or both simultaneously/sequentially. This multi-functionality enables a single cooling section to handle diverse steel production requirements, from low cooling rate applications to high cooling rate applications, and from oxidation-sensitive steels to those requiring rapid quenching.
4Device complexity
If the cooling section uses fixed cooling rates, then simple control is maintained, but different cooling rates cannot be applied to produce most types of steel
Solution Approach 1:
The cooling section employs controllable and adjustable cooling rates through variable speed drives on spray nozzles, adjustable gas flow rates, and programmable temperature profiles. These dynamic control capabilities allow the system to adapt cooling rates to specific steel types while maintaining relatively simple operational interfaces through centralized control systems.
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 enhances productivity by allowing high mechanical property steel production directly suitable for galvanizing, with flexible operation for different steel types and precise control over mechanical and metallurgical properties, while preventing atmosphere mixing and ensuring safety.
Implementation Method 1
Gas cooling, typically by spraying a high-speed, high-hydrogen mixture of nitrogen and hydrogen (N2H2), allows cooling rates of around 200 °C/s for 1 mm thick steel strips
Implementation Method 2
The wet cooling zone may include nozzles arranged to spray the liquid or gas-liquid mixture onto the steel strip. The liquid may be water, an acidic solution, or any other solution. The wet cooling zone allows cooling rates of around 1000 °C/s to be achieved
Implementation Method 3
The cooling section according to the invention further comprises an airlock for separating atmospheres between the dry cooling zone and the wet cooling zone
Data Source
Figure 1
Figure 2
AI summary
Section for cooling a steel strip continuous annealing or galvanising line that is designed to receive a metal strip (1), said section comprising at least one dry cooling region (2) that is designed to spray a gas onto said steel strip, and at least one wet cooling region (5) that is designed to spray a liquid or a mixture of gas and liquid onto said steel strip.