Helical Stirring Blade Gradient Design for Dead Space Reduction
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Solution Overview
Problem
Existing mixing devices for solids are often expensive and complex, leading to dead space issues that hinder batch-wise operation in pharmaceutical production, causing carryover and poor traceability.
Innovation Solution
A mixing device with helical stirring blades having sections with varying gradients and scrapers, designed to minimize dead spaces, allowing for efficient mixing and operation in pharmaceutical production, including granulating and drying of solids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mixing devices use several stirring axes with complex geometry to avoid collisions, then mixing reliability is improved, but device complexity increases and dead space is created
Solution Approach 1:
The stirring blade is divided into multiple sections (first section with constant gradient, second section with variable gradient, third section with constant gradient) along the axial direction. Each section has different gradient characteristics that work together to eliminate dead space and prevent collisions, resolving the contradiction between reliability and complexity by segmenting the blade into functional zones.
Solution Approach 2:
Different sections of the stirring blade have locally optimized gradient properties. The first and third sections have constant gradients for stable material transport, while the second section has a variable gradient for enhanced mixing action. This local differentiation allows the blade to perform multiple functions simultaneously, improving reliability without requiring multiple separate stirring axes.
2Reliability
If mixing devices are designed with complex multi-axis stirring, then mixing effectiveness is improved, but dead space increases causing carryover between batches
Solution Approach 1:
The stirring blade is designed with dynamic gradient characteristics along its axial length, allowing different sections to perform different functions during rotation. The variable gradient in the second section creates adaptive flow patterns that effectively sweep the mixing container, eliminating dead spaces and preventing material carryover between batches while maintaining mixing effectiveness.
Solution Approach 2:
The invention introduces axial dimensionality to the stirring blade design by varying the gradient along the axial direction. This three-dimensional gradient structure (radial and axial components) creates complex flow patterns that eliminate dead spaces without requiring multiple stirring axes, thus preventing carryover while maintaining mixing effectiveness.
3Ease of manufacture
If stirring blades have uniform gradient design, then manufacturing is simplified, but dead spaces are created reducing mixing efficiency
Solution Approach 1:
The stirring blade employs local quality differentiation with constant gradients in the first and third sections for ease of manufacturing, while the second section features a variable gradient optimized for eliminating dead spaces. This localized variation in gradient properties maintains manufacturing simplicity for most of the blade while enhancing mixing efficiency in critical zones.
Solution Approach 2:
The blade is segmented into three distinct gradient zones along the axial direction, with the first and third sections having constant gradients that are easier to manufacture, and the second section having a variable gradient that improves mixing efficiency. This segmentation allows combination of manufacturability and performance optimization.
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 device reduces dead spaces, enabling effective mixing and traceability in pharmaceutical production, with features like adjustable gradient sections and scrapers facilitating radial transport and efficient powder handling.
Implementation Method 1
a stirring element (4) which has at least two helical stirring blades (7, 8) which are connected to a motor-driven shaft (5)
Implementation Method 2
the strippers, also called fins, make it possible for the solids present in the mixing container to be transported during mixing in a radial direction inside the mixing container in the direction of the motor-driven shaft
Data Source
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AI summary
The present invention relates to a mixing device (1), especially for mixing solids in a mixing vessel (2), comprising a stirring element (4) having at least two helical stirrer blades (7, 8) connected to a motor-driven shaft (5), wherein the stirrer blades (7, 8) have a first portion (10), a second portion (11) and a third portion (12), every one of these portions (10, 11, 12) has a constant gradient (m1, m2, m3) of one steepness or a gradient (m1, m2, m3) which is different from the constant gradient and has a curvature, and at least one of the constant gradients (m1, m2, m3) has a steepness different from the at least one other constant gradient (m1, m2, m3), or one of the different gradients (m1, m2, m3) has a curvature that is different from the at least one other different gradient (m1, m2, m3).