Two-Stage Cooling Headers for Hot-Rolled Steel Strip
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Solution Overview
Problem
Existing cooling techniques for hot-rolled steel strips face challenges in precisely controlling the cooling rate and amount of cooling water, especially on the lower surface where space is limited, leading to difficulties in regulating the liquid level and flow rate due to water splashing and corrosion issues with nozzle height adjustment.
Innovation Solution
A cooling method and apparatus using multiple cooling headers with independently controlled supply systems for each set of spray nozzles, allowing for two-stage regulation of cooling water flow by alternating the number of active pipes and nozzle positions to achieve precise control of cooling rates on both the upper and lower surfaces of the steel strip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If spray pressure is decreased to reduce cooling rate, then cooling rate is reduced, but flow rate change becomes very small making it difficult to largely change cooling rate
Solution Approach 1:
The cooling apparatus is divided into multiple independent pipe systems (first system, second system, third system) that can be operated separately. By selectively activating different pipe systems, the apparatus can achieve discrete steps of cooling rate reduction without requiring continuous pressure adjustment, thus overcoming the limited control range of single-system pressure regulation.
Solution Approach 2:
The system dynamically switches between different pipe system configurations (one system active, two systems active, three systems active) to adapt cooling rate to varying requirements. This dynamic reconfiguration allows large changes in cooling rate by simply adding or removing active pipe systems rather than making small incremental pressure adjustments.
2Temperature
If a large amount of cooling water is poured on thin steel strips to achieve high cooling rate, then cooling rate is increased, but the steel strip bounds or loops due to fluid resistance
Solution Approach 1:
The cooling water application is segmented into multiple pipe systems that can be independently controlled. For thin steel strips, only the necessary number of pipe systems are activated to provide sufficient cooling while avoiding excessive water flow that would cause bounding or looping. This segmented approach allows precise matching of water flow to strip thickness and cooling requirements.
Solution Approach 2:
Different pipe systems are positioned at different locations along the strip width and conveying direction. The system applies cooling water locally where needed based on strip thickness and desired cooling rate, rather than uniformly across the entire strip surface. This localized cooling prevents excessive fluid resistance on thin strips while maintaining effective cooling where required.
3Quantity of substance
If nozzle height is adjusted to control cooling water flow rate, then flow rate control is achieved, but corrosion occurs and reliability is reduced
Solution Approach 1:
The system replaces the mechanical adjustment method (changing nozzle height) with a fluid control method (regulating flow rate through valve openings). This substitution eliminates the mechanical wear and corrosion issues associated with adjustable nozzle mechanisms, as the nozzles remain in fixed positions and only the flow rate is controlled through valve openings, significantly improving reliability and durability.
4Temperature
If spray pressure is increased to increase flow rate, then cooling rate is improved, but water usage increases and energy is wasted
Solution Approach 1:
Instead of using a single high-pressure system that consumes excessive water and energy, the cooling apparatus segments the cooling function into multiple pipe systems. Each system operates at optimized pressure levels, and only the necessary number of systems are activated based on cooling requirements. This segmentation allows achieving the desired cooling rate with lower overall water consumption and energy usage compared to a single high-pressure system.
Solution Approach 2:
The system applies partial cooling action by activating only the necessary number of pipe systems (one, two, or three systems) based on the actual cooling requirements. Rather than always operating at maximum capacity with all systems active, the apparatus uses partial action to match cooling demand, thereby avoiding excessive water usage and energy waste while still achieving the required cooling rate.
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 allows for efficient, rapid, and precise control of cooling rates on hot-rolled steel strips, reducing material defects and maintaining material quality without the need for additional elements, while minimizing water usage and preventing corrosion.
Implementation Method 1
the hot-rolled steel strip is cooled using cooling water (water cooling) by a cooling apparatus during hot rolling
Implementation Method 2
cooling water is sprayed from the spray nozzles onto the steel strip
Data Source
AI summary
Provided are a cooling method and a cooling apparatus that, in the cooling of a hot-rolled steel strip, regulates the amount of cooling water in a two-stage manner for each set of headers in the width direction and changes the rate at which the steel strip is cooled, in a multistage manner by a simple method, and that is effective particularly in cooling the lower surface of the steel strip, where space is narrow. The spray nozzles 5 are arranged in a row in the width direction of the steel strip at a predetermined pitch. Two systems of cooling headers 6 are arranged for one set so that spray nozzles 5 adjacent in the width direction can be supplied with cooling water from different pipe systems, and a spray valve 7 is attached to each cooling header 7 so that spraying/stop of spraying of cooling water can be individually performed.