Combined Screw-Pneumatic Feeder for Melt-Stable Plastic Feeding
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Solution Overview
Problem
Existing feeders for plastic materials face issues such as melting and instability due to high temperatures, and impurities causing deposits around screw axes, making stable feeding challenging, especially in processes like gasification, pyrolysis, and combustion.
Innovation Solution
A combined feeder comprising a screw feeder part and a pneumatic feeder part, using a screw to transfer plastic material and cooling devices to maintain below melting temperatures, followed by a pneumatic feeder part that introduces steam or oxygen-containing gas to form a stable mixture with the plastic, preventing overheating and facilitating stable feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a screw feeder is used to feed plastic material, then the plastic material can be transferred to the process, but the plastic components may melt in the screw causing unstable feeding
Solution Approach 1:
The feeder is divided into two separate parts: a screw feeder part for initial material transfer and a pneumatic feeder part for final delivery. This segmentation allows each part to perform its function optimally - the screw part handles bulk transfer while the pneumatic part handles the temperature-sensitive final feeding, preventing melting and ensuring stability.
Solution Approach 2:
The pneumatic carrier gas acts as an intermediary medium between the screw feeder and the process. It receives the plastic material from the screw feeder and transports it to the process without direct contact with hot surfaces, preventing melting while maintaining feeding stability.
2Productivity
If a screw feeder is used to feed plastic material, then the plastic material can be transferred, but impurities cause deposits around screw axes
Solution Approach 1:
The harmful function of deposit formation around the screw axis is eliminated by extracting the material from the screw feeder before it completes its cycle. The pneumatic feeder takes over at the discharge point, preventing impurities from circulating back and forming deposits on the screw, thus maintaining continuous feeding capability.
Solution Approach 2:
The mechanical screw feeding system is partially replaced with a pneumatic system for the final delivery stage. This substitution eliminates the mechanical contact between impurities and the screw axis, preventing deposit formation while maintaining continuous feeding productivity.
3Use of energy by moving object
If high temperature is used in the process, then energy efficiency is improved, but plastic material melts causing feeding instability
Solution Approach 1:
The feeding system is segmented into a thermal zone (screw feeder operating at lower temperature) and a high-temperature process zone. The pneumatic carrier transports material through an intermediate zone, allowing the process to operate at high temperature for energy efficiency while the feeding mechanism remains in a lower temperature zone for reliability.
Solution Approach 2:
The pneumatic carrier gas serves as a thermal intermediary, transporting plastic material from the low-temperature screw feeder to the high-temperature process without exposing the material to temperatures that would cause melting, thus maintaining feeding stability while allowing energy-efficient high-temperature processing.
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
The combined feeder ensures stable and efficient feeding of plastic materials to high-temperature processes like gasification and pyrolysis without melting, allowing for continuous operation and improved recycling of plastic waste, while avoiding contact with hot surfaces.
Implementation Method 1
The pneumatic feeder part arranged after the screw feeder part comprises at least one inlet to supply pneumatic carrier material (3) which is steam to the plastic containing raw material (2) in the pneumatic feeder part for forming a mixture of the plastic containing raw material and steam
Data Source
AI summary
The invention relates to a feeder and method for feeding raw material which comprises plastic to a gasification, pyrolysis or combustion furnace, in which the feeder comprises a screw feeder part and a pneumatic feeder part in order to form a combined feeder for feeding the raw material, the screw feeder part comprises at least a screw to transfer the raw material to the pneumatic feeder part and at least one cooling device to cool the raw material in the screw feeder part, and the pneumatic feeder part arranged after the screw feeder part comprises at least one inlet to supply pneumatic carrier material to the raw material in the pneumatic feeder part for forming a mixture of the raw material and pneumatic carrier material.