Dryer Contact Heater Control for Sheet Cockling
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Solution Overview
Problem
Conventional dryers for continuous sheets face inefficiencies in drying due to cockling and uneven heat distribution, which can lead to reduced productivity and longer drying times, especially when dealing with thick sheets.
Innovation Solution
The dryer employs a combination of contact and non-contact heating elements, including a hot air generator and a controller that adjusts the heating temperature of the contact heater to maintain a higher temperature until the hot air reaches a predetermined temperature, ensuring efficient drying by optimizing the contact distance and curvature of heating rollers and drums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional dryer uses only hot air blowing for drying continuous sheets, then the drying process can be simplified, but drying efficiency is reduced and drying time is extended especially for thick sheets
Solution Approach 1:
The dryer is divided into multiple independent heating zones (first heating zone with contact heater, second heating zone with hot air blower, third heating zone with infrared heater). Each zone uses a different heating method, allowing simultaneous operation of multiple heating mechanisms to accelerate the drying process while maintaining efficiency.
Solution Approach 2:
The invention combines three different heating methods (contact heating, hot air blowing, and infrared radiation) into a single dryer system. This multi-modal heating approach addresses the limitation of using only hot air blowing, significantly improving drying efficiency for both thin and thick continuous sheets.
2Productivity
If the contact heater operates at high temperature from the start, then drying efficiency is improved, but cockling of the continuous sheet occurs due to uneven heat distribution
Solution Approach 1:
The contact heater is pre-heated to a predetermined temperature before the continuous sheet is fed into the dryer. This preliminary heating ensures that when the sheet enters the drying zone, the contact heater is already at optimal temperature, enabling immediate efficient drying without causing thermal shock or cockling from sudden high-temperature contact.
Solution Approach 2:
Different heating methods are applied to different zones of the dryer. The contact heater provides localized intense heat at the first heating zone, while hot air blowers provide gentler distributed heating in the second zone, and infrared heaters provide radiation heating in the third zone. This spatial differentiation of heating quality prevents cockling while maintaining high drying efficiency.
3Productivity
If the dryer uses multiple heating zones with different heating methods, then drying efficiency is improved, but device complexity increases
Solution Approach 1:
The dryer is segmented into three distinct heating zones, each with a specific heating method optimized for particular drying requirements. This segmentation allows independent control and optimization of each heating mechanism, achieving high overall drying efficiency while maintaining manageable structural complexity through modular design.
4Loss of time
If hot air temperature is increased to accelerate drying, then drying time is reduced, but uneven heat distribution causes cockling
Solution Approach 1:
The drying process is segmented into multiple zones with progressively different heating intensities. The first zone uses contact heating for rapid initial moisture removal, the second zone uses hot air blowing at controlled temperatures for continued drying, and the third zone uses infrared radiation for final drying. This segmentation allows high temperatures to be applied without causing cockling, as each zone handles a different stage of the drying process.
Solution Approach 2:
The invention changes the heating parameter (heating method) across different zones rather than uniformly increasing hot air temperature throughout. By varying the heating mechanism from contact to hot air to infrared radiation, the system achieves rapid drying without the cockling that would result from uniformly high hot air temperatures.
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 reduces cockling, increases drying efficiency, and shortens the drying time for both thin and thick continuous sheets, enhancing productivity by ensuring uniform heat distribution and effective moisture evaporation.
Implementation Method 1
a contact heater to contact and heat the drying object
Implementation Method 2
a hot air generator to generate hot air to be blown onto the drying object
Implementation Method 3
ensuring uniform heat distribution and effective moisture evaporation
Data Source
AI summary
A dryer for drying a drying object includes a hot air generator to generate hot air to be blown onto the drying object, a contact heater to contact and heat the drying object, and a controller to control a heating temperature of the contact heater and a temperature of the hot air. The controller controls the heating temperature of the contact heater to be above a first predetermined temperature from a start of generation of the hot air by the hot air generator until the temperature of the hot air reaches a second predetermined temperature.