Nitrogen Cloud Apparatus for Hot Dip Coated Steel Oxidation Prevention
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Solution Overview
Problem
Existing methods for forming a non-oxidation atmosphere in hot-dip metal coated steel sheet production, such as the box-type apparatus, suffer from deformation due to heat, malfunctioning of electric devices, reduced cooling efficiency, difficulty in removing top dross, and excessive nitrogen gas usage, leading to compromised surface quality and increased costs.
Innovation Solution
A device is installed between the coating bath and the air knife, forming a nitrogen curtain with lower and upper gas discharge bars to prevent oxidation, allowing for efficient cooling and reduced nitrogen usage by maintaining a non-oxidation atmosphere only in the required partial space, thereby minimizing heat-related issues and nitrogen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a box-type apparatus is used to form a non-oxidation atmosphere, then oxidation prevention is achieved, but heat causes deformation and malfunctioning of electric devices
Solution Approach 1:
The patent divides the non-oxidation atmosphere formation into segmented gas discharge bars (lower and upper bars with multiple nozzles) rather than using a complete box-type enclosure. This segmentation allows nitrogen gas to be discharged only in specific regions where oxidation prevention is needed, avoiding the need for a fully enclosed hot box that would trap heat and cause deformation.
Solution Approach 2:
The invention applies the non-oxidation atmosphere locally rather than globally. Gas discharge bars are positioned specifically at the coating bath surface and air knife regions where oxidation would most adversely affect surface quality. This local application prevents oxidation in critical areas without creating a fully enclosed hot environment that would cause thermal deformation.
2Reliability
If a box-type apparatus is used to form a non-oxidation atmosphere, then oxidation prevention is achieved, but cooling efficiency is reduced
Solution Approach 1:
The segmented gas discharge structure allows cooling to proceed efficiently in areas not covered by nitrogen discharge. The lower gas discharge bars are positioned to protect the coating bath surface while leaving the air knife and subsequent cooling zones accessible to ambient air flow, maintaining effective heat dissipation.
Solution Approach 2:
The invention extracts the nitrogen gas discharge function from a fully enclosed box structure and implements it as separate, localized discharge bars. This extraction allows the cooling function to operate independently in the air knife and post-coating zones without being trapped by a封闭 enclosure, thus maintaining cooling efficiency.
3Reliability
If a box-type apparatus is used to form a non-oxidation atmosphere, then oxidation prevention is achieved, but top dross removal becomes difficult
Solution Approach 1:
The gas discharge system is segmented into lower bars positioned at the coating bath surface and upper bars positioned at the air knife region. This segmentation creates an open structure that allows easy access to the coating bath surface for top dross removal operations, unlike a fully enclosed box that would require opening doors or hatches.
Solution Approach 2:
The invention extracts the top dross removal function from the enclosed box structure, allowing operators to access and remove top dross directly from the coating bath surface. The open design with localized gas discharge bars facilitates easy manual or mechanical dross removal while still maintaining oxidation prevention where needed.
4Reliability
If a box-type apparatus is used to form a non-oxidation atmosphere, then oxidation prevention is achieved, but nitrogen gas usage becomes excessive
Solution Approach 1:
The gas discharge system is divided into lower bars (discharging toward the coating bath surface) and upper bars (discharging toward the air knife region). This segmentation allows nitrogen gas to be discharged only in specific zones where oxidation prevention is critical, rather than filling an entire box enclosure, thus significantly reducing nitrogen consumption.
Solution Approach 2:
The invention applies the non-oxidation atmosphere partially rather than completely. By discharging nitrogen gas only in the coating bath surface and air knife regions where oxidation would most adversely affect surface quality, the system achieves adequate oxidation prevention with minimal nitrogen gas usage, avoiding the excessive consumption that would result from filling a complete box enclosure.
Data Source
AI summary
A device installed between a surface of a coating bath and an air knife equipment to produce a hot dip metal coated steel sheet to form a non-oxidation atmosphere in a surface of a coated steel sheet ascending from the coating bath, the device comprising: lower gas discharge bars spaced apart from the surface of the coating bath by a predetermined distance and discharging a non-oxidation gas in a direction of the surface of the coating bath along the surface of the coated steel sheet; a side cover extending upwardly slopingly in a direction of the coated steel sheet from the sides of the lower gas discharge bars; and upper gas discharge bars formed at an upper end of the side cover and discharging a non-oxidation gas downwardly.