Plastic Granulate Drying with Dew Point Control
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Solution Overview
Problem
Existing methods for drying plastic granules, such as compressed air dryers, are energy-intensive and cost-inefficient due to the high complexity and cost of generating compressed air, which is required in large quantities for effective drying.
Innovation Solution
A method and device that utilize a closed drying air circuit with a dew point control system, where expanded compressed air is circulated until it reaches a predetermined dew point threshold, allowing for maximum water absorption capacity before exhaustion, and heat is supplied to enhance water release from the granules, significantly reducing the volume of compressed air needed for drying by up to 90%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If compressed air is used to dry plastic granules, then drying effectiveness is improved, but energy consumption and cost increase significantly
Solution Approach 1:
The patent implements periodic action by cyclically switching between compressed air supply and recirculation modes. The control unit opens the compressed air supply valve periodically to recharge the drying air with fresh low-dew-point air, then closes it to recirculate and utilize the drying air's heat content, thereby reducing overall energy consumption while maintaining drying effectiveness
Solution Approach 2:
The patent applies discarding and recovering by capturing the exhaust air that has absorbed moisture from the granules and recirculating it back into the drying system. The control unit manages this by closing the exhaust valve and opening the recirculation valve, allowing the warmed drying air to be reused rather than discarded, thus recovering thermal energy and reducing the need for continuous compressed air generation
2Productivity
If large volumes of compressed air are supplied to dry granules, then drying speed is improved, but system complexity and cost increase
Solution Approach 1:
The patent implements universality by designing the drying air circuit to serve multiple functions: the same circuit handles both the supply of fresh compressed air and the recirculation of used drying air. The control unit manages these different modes using the same physical infrastructure (valves, pipes, fans), eliminating the need for separate systems and reducing overall complexity while maintaining high drying speed
Solution Approach 2:
The system applies self-service by using its own exhaust air as part of the drying medium. The recirculation fan and valve system automatically redirects moisture-laden exhaust air back into the drying chamber, allowing the system to sustain its own drying process without requiring entirely fresh air for every cycle, thereby reducing the burden on the compressed air generation system
3Loss of energy
If compressed air is circulated and reused, then energy saving is improved, but control precision is required
Solution Approach 1:
The patent implements feedback by using a dew point sensor to continuously monitor the condition of the drying air and feeding this information back to the control unit. The control unit adjusts the operation of the compressed air supply valve, exhaust valve, and recirculation valve based on the actual dew point measurement, ensuring precise control of the drying air's moisture content while maximizing energy savings through intelligent recirculation decisions
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 a considerable energy saving and cost-effective drying process, where the air volume required is minimized to only what is necessary for absorbing and transporting away moisture, thereby optimizing the drying efficiency and reducing energy consumption.
Implementation Method 1
heat is supplied to enhance water release from the granules
Implementation Method 2
the expanded air has a dew point of approx. -25 °C. The dew point is the temperature at which the moisture contained in the air condenses on an object
Implementation Method 3
heat is supplied to enhance water release from the granules
Data Source
Figure 1
AI summary
The invention relates to a method for drying plastic granules, wherein a quantity of expanded compressed air is initially supplied to the plastic granules as drying air. This drying air is then circulated through the plastic granules until their dew point reaches a predetermined dew point threshold (saturation dew point). Saturated air is then repeatedly withdrawn from the circulating system and further expanded compressed air is supplied until a desired dew point of the circulating drying air is reached. This drying air is then circulated again until it reaches the dew point threshold. The invention further relates to a device for carrying out such a method.