Vertical Dryer With Permeable Walls For Uniform Low-Temperature Drying
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Solution Overview
Problem
Existing dryers for granular materials face issues such as degradation of product quality due to high-temperature drying, short residence times leading to non-uniform drying, risk of explosive atmospheres, and inefficient use of waste heat, particularly in vertical dryers using combustion gases and outside air.
Innovation Solution
A vertical dryer design featuring permeable walls allowing crosswise air flow for convection drying, with a holding and discharge system for controlled exposure and potential air recycling, utilizing waste heat from low-temperature sources, and minimizing equipment wear with few moving parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-temperature drying (>100°C) is used to reduce equipment size and increase productivity, then drying speed improves, but product quality degrades and explosive atmospheres are created
Solution Approach 1:
The patent changes the drying temperature parameter from high (>100°C) to low (below 100°C), and changes the drying mechanism from contact heating to convective drying. This allows maintaining productivity while improving product quality and eliminating explosive risks by using permeable walls that allow hot air to circulate through the material without direct surface contact.
Solution Approach 2:
The patent replaces the mechanical contact heating system (drums, belts, direct flame) with a convective drying system using permeable walls. Hot air is generated externally and circulated through the material via the permeable walls, eliminating the need for mechanical contact with hot surfaces while maintaining drying effectiveness.
2Productivity
If short residence time is used to reduce equipment size, then productivity improves, but uniform drying cannot be achieved
Solution Approach 1:
The patent introduces a new spatial dimension for heat and mass transfer by using permeable walls that allow three-dimensional air circulation through the material. This enables efficient convective drying throughout the entire material volume, achieving uniform drying even with short residence times because moisture can escape from the interior through the permeable walls without requiring long external surface exposure.
3Power
If high-temperature equipment is used, then drying capability improves, but waste heat utilization is limited
Solution Approach 1:
The patent changes the operating temperature parameter from high to low, which expands the range of usable waste heat sources. Instead of requiring high-temperature waste heat (>100°C), the system can now utilize low-temperature waste heat from sources like cogeneration systems and organic Rankine cycles, significantly improving adaptability and versatility in waste heat utilization while maintaining effective drying capability.
4Device complexity
If conventional drying methods are used, then drying process is simple, but air recycling capability is minimal or nonexistent
Solution Approach 1:
The patent implements a feedback mechanism where exhaust air containing moisture is recirculated back through the permeable walls to the material. This creates a closed-loop system that continuously removes moisture while recycling the bulk of the air, improving energy efficiency without significantly increasing system complexity because the recirculation utilizes the existing permeable wall structure.
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
Achieves uniform drying at low temperatures, preserving product quality, enabling efficient use of waste heat, and reducing equipment maintenance while ensuring safety by avoiding direct contact with hot surfaces.
Implementation Method 1
the product is dried by convection thanks to the stream of hot air flowing crosswise to the permeable walls
Implementation Method 2
the material to be dried glides vertically by force of gravity between permeable walls
Data Source
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AI summary
A vertical dryer that comprises: - a first permeable wall (1) and a second permeable wall (2) configured so as to confine a material to be dried in between the two walls (1, 2) and to allow a stream of air to pass through crosswise to the two walls (1, 2) to dry the confined material, both permeable walls (1, 2) comprising both lengthwise ends corresponding to the inlet and outlet for the material to be dried, - a holding and discharge system (4) adapted to retain the material being dried in the space between the two permeable walls (1, 2) and to discharge the material being dried by gravity, the holding and discharge system (4) being located at the lengthwise end of the permeable walls (1, 2) at the outlet for the dried product, - a forced air system configured to move a stream of air through the permeable walls (1, 2) and the material to be dried.