Annealing Furnace Cooling Jets for Uniform Lamination Heat Transfer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing annealing furnaces for steel laminations face challenges in increasing productivity due to limitations in the cooling section, which affects conveyor speeds and overall production efficiency, leading to increased costs and potential cosmetic issues from non-uniform cooling.

Innovation Solution

The implementation of a diffused rapid uniform cooling system using a plurality of jets for convection cooling in close proximity to the trays, combined with atmosphere extraction tubes and a recirculation fan, disrupts the stagnant boundary layer and enhances heat transfer efficiency, allowing for increased conveyor speeds and a potential lengthening of the heating section.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the cooling section is lengthened to increase productivity, then conveyor speeds can be increased, but the furnace length and construction cost increase

Engineering Contradiction:

Improveconveyor speedVSAvoidfurnace length

Core Design Contradiction:

ProductivityVSLength of stationary object

Solution Approach 1:

The patent changes the cooling parameters by introducing forced convection with high-velocity jets directly beneath the trays, replacing the traditional slow natural cooling method. This parameter change in cooling intensity allows the cooling section to be shortened while maintaining the same cooling effectiveness, thereby enabling higher conveyor speeds without increasing furnace length.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses high-velocity gas jets (pneumatic system) to enhance heat transfer from the trays. The jets are positioned directly beneath the trays and deliver high-velocity cooling gas that disrupts the stagnant boundary layer, dramatically improving cooling efficiency and allowing for a more compact furnace design.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Productivity

If the cooling section is lengthened to maintain soak time, then productivity improves, but construction cost and energy consumption increase

Engineering Contradiction:

Improveproduction efficiencyVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by stationary object

Solution Approach 1:

The patent fundamentally changes the cooling mechanism from passive natural convection to active forced convection with high-velocity jets. This parameter change increases the heat transfer coefficient dramatically, allowing the cooling section to be shortened while maintaining the required cooling effectiveness, thereby reducing energy consumption and construction costs.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional cooling tubes are used at a distance from the conveyor, then the structure is simple, but cooling uniformity and efficiency are poor

Engineering Contradiction:

Improvecooling structure simplicityVSAvoidcooling uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent moves the cooling jets from a distant position to a position directly beneath the trays, changing the spatial dimension of heat transfer. This dimensional change brings the cooling source into direct contact with the load, disrupting the stagnant boundary layer and achieving uniform, high-efficiency cooling without complex tube arrangements.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent applies cooling locally and directly at the point of heat generation (beneath the trays), rather than using distributed cooling tubes. This local quality approach concentrates the cooling effect where it is most needed, achieving superior cooling uniformity and efficiency.

Inventive Principle:

Principle #3Local quality

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 results in improved productivity by achieving 20 to 30% increase in efficiency, ensuring uniform surface temperatures and preventing cosmetic issues, while maintaining the structural integrity of the furnace without excessive retrofitting costs.

Implementation Method 1

a plurality of jets for convection cooling are provided in close proximity to trays carrying product to be cooled

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

Atmosphere extraction tubes are provided to collect and recirculate the atmosphere being expelled at the convection jets

Methodology Applied

Scientific EffectGas flow:

Implementation Method 3

a recirculation fan, which forces the atmosphere through the jets and cools the atmosphere

Methodology Applied

Scientific EffectForced convection: Forced Convection

Data Source

PatentUS7371296B1Annealing furnace cooling and purging system and method

Publication Date: 2008.05.13 PNC BANK NA

AI summary

In a method and system for an improved annealing furnace cooling and purging, atmosphere injection jets are provided in close proximity to a bottom of a tray carrying a lamination product in a cooling section. Atmospheric extraction tubes are also provided extracting atmosphere which is delivered to a high temperature variable speed fan which then outputs at a pressure side atmosphere to tubes having the injection jets. The system may be retrofit into an existing annealing furnace already having water cooled finned tubes and a recirculation fan in the cooling section. Cooling water tubes and a recirculating fan may also be provided in a purge vestibule located after an output from the cooling section for additional cooling.