Helical Extrusion Die for Catalyst Particle Shape Control
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Solution Overview
Problem
Conventional dies for extruding catalyst particles in the Fischer-Tropsch process fail to maintain the helically wound shape and intended pitch, leading to increased pressure drop and reduced effectiveness due to entanglement and deviation of exit angle, resulting in suboptimal catalyst performance.
Innovation Solution
A die design with a first section having a helical bore and a second section with a cylindrical bore, where the cylindrical section is at least twice as long as the helical section, helps preserve the helical shape and pitch by minimizing entanglement and controlling the exit angle, thereby producing catalyst particles with reduced pressure drop and improved surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If catalyst particle size is reduced to increase surface area, then surface area increases, but pressure drop increases significantly
Solution Approach 1:
The die incorporates a helical bore with curved geometry instead of a straight cylindrical bore. This helical curvature transforms the extrusion path, creating particles with a characteristic helical shape that reduces inter-particle entanglement and improves flow characteristics, thereby reducing pressure drop while maintaining surface area
2Shape
If conventional helical bore die is used, then helical shape is intended, but entanglement and exit angle deviation occur causing shape loss
Solution Approach 1:
The die bore is divided into two distinct sections: a first section with helical geometry to create the helical shape, and a second section with straight cylindrical geometry to maintain and stabilize the shape during exit. This segmentation allows each section to perform its specific function optimally without interference
Solution Approach 2:
The invention adds a longitudinal dimension to the die design by extending the bore length with a second section. This additional dimensional space allows the extrudate to complete its helical formation in the first section and then stabilize in the second section, preventing exit angle deviation and maintaining pitch uniformity
3Shape
If helical bore length is increased to improve shape, then shape quality improves, but device complexity increases
Solution Approach 1:
The die bore is segmented into two functional sections with distinct geometries. The first section (helical) and second section (straight) are clearly defined, allowing for optimized design of each segment while keeping the overall structure manageable and manufacturable
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 die design significantly reduces the defect rate of extrudates with non-uniform pitch, achieving a lower pressure drop and enhanced catalytic performance by maintaining the intended helical form and pitch, leading to improved hydrocarbon yield and selectivity in the Fischer-Tropsch process.
Implementation Method 1
from the inlet to the outlet each channel comprises a first section with a helical bore with a non-circular cross-section
Implementation Method 2
feed a paste comprising a support material and optionally a catalytically active component or a precursor thereof from a hopper or compactor into an extruder
Data Source
AI summary
A die is provided for extruding elongate particles suitable for use in catalysis. The die comprises a plurality of channels extending from an inlet to an outlet. From the inlet to the outlet each channel comprises a first section with a helical bore with a non-circular cross-section, and a second section with a cylindrical bore. The cylindrical bore of the second section which has a diameter equal or greater than that of the first section. The second section is at least twice as long as a diameter of the first section.