Hot Strip Cooling Nozzle Dynamics and Segmentation
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Solution Overview
Problem
Existing cooling technologies for hot strips in hot rolling lines face challenges in achieving uniform cooling due to residual coolant, leading to temperature unevenness and material inconsistencies, with previous solutions either causing damage to the strip or increasing facility costs.
Innovation Solution
A cooling device with diagonally injected rod-like coolant flows from opposing header groups, allowing independent ON-OFF control and adjustable water amount density, which ensures uniform cooling by effectively managing residual coolant and preventing thermal deformation of nozzles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If coolant is injected from nozzles disposed adjacent to the steel plate, then cooling rate is maintained over a wide range, but the steel plate may impinge against the nozzle to be damaged and the manufacturing line is interrupted
Solution Approach 1:
The nozzle is designed to be movable in the vertical direction, transitioning between a lower position for normal cooling operation and an upper position for avoiding impingement damage. This dynamic adjustment allows the system to maintain high cooling rates while preventing nozzle damage from warped strip edges
Solution Approach 2:
The nozzle is retracted to the upper position in advance before the warped leading end or trailing end of the steel plate enters the cooling zone. This preliminary action prevents contact between the nozzle and the warped edges, avoiding damage before it occurs
2Reliability
If the lift mechanism is operated to retract the nozzle, then the nozzle is protected from damage, but the leading end or trailing end cannot be sufficiently cooled
Solution Approach 1:
The cooling headers are divided into multiple sections along the conveying direction of the strip. This segmentation allows different zones of the strip to receive cooling independently, ensuring that the leading end and trailing end are sufficiently cooled even when the nozzle is retracted to protect from impingement damage
3Manufacturing precision
If the slit nozzle is employed to form coolant film, then uniform cooling is achieved, but the gap control is difficult due to thermal deformation of the nozzle
Solution Approach 1:
The invention changes the physical state of the coolant from a film state (requiring precise gap control) to a spray state (less sensitive to gap variations). By injecting coolant as droplets or spray rather than a continuous film, the system achieves uniform cooling without the need for precise gap control between the nozzle and the strip, thereby eliminating the problem of thermal deformation affecting gap dimensions
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
The solution provides stable and uniform cooling of hot strips at high rates, reducing material unevenness and yield loss while maintaining quality, and is cost-effective by minimizing facility length and preventing coolant scattering.
Implementation Method 1
the residual coolant in the film boiling state is transformed into the transition boiling state or the nucleate boiling state to intensify the cooling capability
Implementation Method 2
the residual coolant on the strip, which will be described taking the case for cooling the strip with the coolant on the run out table
Data Source
Figure 1~2
Figure 3A~4
Figure 5~6
AI summary
A cooling device and a cooling method for a hot strip allow uniform and stable cooling of the strip at a high cooling rate when supplying the coolant to the upper surface of the hot strip. The cooling device includes an upper header unit 21 for supplying a rod-like flow to the upper surface of the strip 10. The upper header unit 21 is formed of the first upper header group including plural first upper headers 21a arranged in a conveying direction and a second upper header group including plural second upper headers 21b arranged in the conveying direction. The cooling device is provided with an ON-OFF mechanism 30 to allow each of the upper headers 21a and 21b of the first and the second upper header groups to independently execute the ON-OFF control (start/end injection control) of an injection (feeding) of the rod-like flow.