Polymer Drying Hopper Screw Torque Feedback Control
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Solution Overview
Problem
The challenge lies in efficiently drying polymer granular materials with high hygroscopic properties, such as PET, PA, and PC, to achieve low humidity levels required for extrusion or molding while minimizing energy consumption and maintaining stable drying conditions, as existing methods are energy-intensive and prone to instability due to variations in material parameters and operator errors.
Innovation Solution
A process and plant configuration that involves a drying hopper with a controlled drying gas flow rate and temperature, where the drying gas flow rate is regulated based on measured control parameters correlated with the screw rotation in the extruder, such as torque, rotation speed, or power consumption, to maintain optimal drying conditions and reduce energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the granular material is dried inside a hopper with continuous hot and dry air flow, then the humidity content is reduced to required levels, but the energy consumption increases significantly
Solution Approach 1:
The patent implements feedback control by measuring control parameters correlated with screw rotation (torque, rotation speed, or power consumption) and using these measurements to dynamically regulate the drying gas flow rate. This closed-loop system adjusts drying conditions in real-time based on actual material state, eliminating the need for continuous high-energy hot air flow while maintaining effective drying.
Solution Approach 2:
The drying gas flow rate is made dynamic rather than continuous and constant. The system adjusts the flow rate based on measured control parameters, providing drying energy only when and where needed during the extrusion process, thereby reducing overall energy consumption while maintaining drying effectiveness.
2Device complexity
If the drying process is operated with fixed parameters, then the setup is simple, but the process becomes unstable due to variations in material parameters and operator errors
Solution Approach 1:
The patent employs feedback control where control parameters (torque, rotation speed, or power consumption) are continuously measured and used to regulate the drying gas flow rate. This automatic adjustment compensates for variations in material parameters and eliminates the impact of operator errors, significantly improving drying process stability without requiring complex manual intervention.
Solution Approach 2:
The system uses the extruder's own operational parameters (screw rotation characteristics) as feedback signals to automatically adjust drying conditions. The process self-regulates based on its own state, making the drying system adaptive to material variations without requiring external complex control mechanisms or operator expertise.
3Productivity
If the drying gas flow rate is high, then the drying speed increases, but the energy consumption and process instability increase
Solution Approach 1:
The drying gas flow rate is dynamically adjusted based on measured control parameters rather than maintained at a constantly high level. The system provides high flow rate only when drying is needed (as indicated by screw rotation parameters), and reduces flow rate when drying requirements are met, thereby maintaining productivity while significantly reducing energy consumption.
Solution Approach 2:
Feedback control enables the system to maintain optimal drying speed by adjusting gas flow rate in response to measured control parameters. The system achieves high drying speed when necessary while automatically reducing energy input when drying requirements are satisfied, eliminating the need for continuously high energy consumption.
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 stabilizes the drying process, reduces energy consumption, and ensures consistent product quality by directly correlating the drying process with the transformation unit's parameters, optimizing energy efficiency and reliability while minimizing processing waste.
Implementation Method 1
a drying stage for the granular material... a continuous flow of hot and dry air is introduced
Implementation Method 2
a continuous flow of hot and dry air is introduced
Implementation Method 3
the granular material is brought to the molten and semi-molten state also as a result of the friction forces with which the material is urged by a screw
Implementation Method 4
the granular material is brought to the molten and semi-molten state also as a result of the friction forces with which the material is urged by a screw
Data Source
AI summary
A process for treating polymer granular material (2) comprising the steps of heating and drying the polymer granular material in a drying hopper (10) by means of a drying gas, discharging a portion of the polymer granular material into an extruder (101), inside which the polymer granular material is brought to a molten or semi-molten state and transported along the extruder by a rotating screw (104) in order to be injected into a mould (102) or caused to pass through an extrusion head. The process provides for measuring a control parameter which is correlated with the rotation of the screw inside the extruder and regulating the flow rate of the drying gas on the basis of the control parameter.