Extruder Screw Design for Low-Temperature Liquid Removal
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Solution Overview
Problem
Existing extruders face challenges in efficiently removing liquids from temperature-sensitive materials without subjecting them to elevated temperatures, as conventional vacuum methods may not be sufficient to achieve low boiling points at low pressures.
Innovation Solution
An extruder design with a barrel and screw featuring a fluid inlet and outlet separated along the barrel wall, creating a pressure difference to facilitate the flow of a fluid through the barrel, allowing for efficient drying or treatment of materials without elevated temperatures, using a screw with varying pitch elements to control material movement and interaction with the fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a vacuum is applied to the extruder barrel to flash evaporate liquids, then liquid removal is improved, but temperature-sensitive materials deteriorate due to insufficient boiling point reduction at low pressure
Solution Approach 1:
A fluid (gas or liquid) is introduced as an intermediary medium to facilitate liquid removal from the material. The fluid flows through the barrel and interacts with the material, enabling liquid extraction without requiring extreme vacuum conditions that would damage temperature-sensitive materials. The fluid acts as a carrier that absorbs or transports the liquid from the material matrix.
Solution Approach 2:
The invention employs pneumatic or hydraulic principles by introducing a fluid through the barrel to achieve liquid removal. Instead of relying solely on vacuum pressure differentials, the system uses fluid flow dynamics (pneumatics for gas, hydraulics for liquid) to create the necessary conditions for liquid extraction while maintaining gentle conditions for heat-sensitive materials.
2Reliability
If the extruder and contents are cooled to preserve temperature-sensitive materials, then material integrity is improved, but liquid removal efficiency deteriorates
Solution Approach 1:
The introduced fluid serves as a mediator that enables liquid removal to proceed effectively at lower temperatures. By providing an alternative mechanism for liquid extraction through fluid interaction rather than thermal evaporation, the system achieves both material preservation and efficient liquid removal simultaneously.
Solution Approach 2:
The invention changes the operational parameters from high-temperature vacuum evaporation to low-temperature fluid-assisted removal. This parameter shift allows the process to operate in a regime where both material integrity and liquid removal efficiency are optimized, avoiding the trade-off between cooling for preservation and heating for evaporation.
3Device complexity
If conventional vacuum ports are used in the barrel wall, then device complexity is minimized, but liquid removal effectiveness deteriorates for temperature-sensitive materials
Solution Approach 1:
The fluid introduced through the barrel acts as a mediator that enhances liquid removal effectiveness without requiring complex vacuum port configurations. The fluid's presence enables more effective liquid extraction through its interaction with the material, achieving better performance with a relatively simple structural modification.
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
Enables partial or total removal of liquids or other treatments within the extruder barrel at controlled temperatures, specifically demonstrated in chocolate crumb processing, reducing post-extrusion drying requirements and maintaining material integrity.
Implementation Method 1
a screw mounted in the barrel for rotation, the screw comprising screw elements... material in the barrel is moved more quickly along the portion of the barrel between the fluid inlet and the fluid outlet than upstream of the said portion
Implementation Method 2
one of the fluid inlet and the fluid outlet being connected to a pump so that there is a pressure difference between the fluid inlet and the fluid outlet
Implementation Method 3
allows drying, that is, partial or total removal of water or other liquid... without the need to subject the material to elevated temperature
Implementation Method 4
flowing a fluid through the extruder barrel... facilitates the flow of a fluid through the barrel, allowing for efficient drying or treatment of materials
Data Source
AI summary
An extruder 10 comprises a barrel 12 and a screw 24 mounted in the barrel for rotation. The screw comprises screw threads 26a, 26b, 26c. The barrel has an inlet funnel 22 toward one end for material to be extruded and a die plate 18 with openings 20 at the other end and an air inlet port 28 toward one end of the barrel and an air outlet port 30 toward the other end. The screw threads are such that material 34 in the barrel is moved more quickly along the portion of the barrel between the air inlet port and the air outlet port than upstream of that portion. The air outlet is connected to a pump 32 so that there is a pressure difference between the air inlet and the air outlet.