Rotary Drum Permeable Plates Vacuum Freeze-Dryer
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Solution Overview
Problem
Freeze-drying processes face inefficiencies due to choked flow conditions, where escaping vapor sweeps away particles, leading to loss and contamination issues, especially with sub-millimeter sized particles, requiring a solution to minimize particle loss while maintaining drying efficiency.
Innovation Solution
A rotary drum design for vacuum freeze-dryers with permeable front and rear plates to control sublimation vapor flow, preventing choke flow conditions by optimizing the permeability of both plates to maintain particles within the drum during the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the drum is made impermeable to vapor, then particles are retained inside the drum, but vapor accumulates causing choked flow conditions that sweep particles out
Solution Approach 1:
The drum is designed with a porous wall structure that allows vapor to permeate through it. This porous construction enables vapor to escape continuously without forming choked flow conditions, while the pore sizes are controlled to prevent particles from passing through. The porous material thus simultaneously achieves vapor transmission and particle retention.
Solution Approach 2:
The porous drum wall acts as an intermediary between the particles and the vacuum environment. It mediates the interaction by allowing vapor to pass through while blocking particles, thus preventing the harmful choked flow effect without requiring the drum to be completely impermeable.
2Object-generated harmful factors
If the drum is made permeable to vapor, then choked flow conditions are prevented, but particles may escape through the permeable structure
Solution Approach 1:
The porous wall structure is designed with specific pore size characteristics that create a size-based filtration effect. The pores are large enough to allow vapor molecules to pass freely but small enough to retain particles, thus achieving selective permeability that prevents both choked flow and particle escape.
3Reliability
If a vacuum-tight drum is used, then complex mechanical configuration is required, but this increases device complexity
Solution Approach 1:
The invention extracts the vacuum sealing function from the rotating drum itself and places it in the stationary housing. The drum no longer needs to be vacuum-tight, eliminating the need for complex vacuum seals on rotating components. The vacuum seal is now a simple stationary interface between the housing and the process chamber.
4Productivity
If vapor escape velocity is high, then drying efficiency is improved, but particles are swept out of the drum
Solution Approach 1:
The porous drum wall provides a distributed escape path for vapor throughout the drum surface. This distributes the vapor flow velocity, preventing localized high-velocity jets that would sweep particles out. The vapor can escape through many small pores simultaneously, maintaining efficient sublimation without creating harmful flow patterns.
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 design reduces drying times and minimizes particle loss, achieving more intense sublimation while maintaining product integrity and efficiency, even with smaller particles, by controlling vapor velocities and ensuring particles remain inside the drum.
Implementation Method 1
Freeze-drying provides for drying of the target product via sublimation of ice crystals into water vapor, i.e., via the direct transition of at least a portion of the water content of the product from the solid phase into the gas phase.
Implementation Method 2
Freeze-drying, also known as lyophilization, is a process for drying high-quality products such as, for example, pharmaceuticals, biological materials such as proteins, enzymes, microorganisms
Implementation Method 3
the rear plate is permeable for sublimation vapor from freeze-drying the particles
Data Source
Figure 1
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Figure 3
AI summary
A rotary drum (302) for use within a vacuum chamber (212) in a vacuum freeze-dryer (204) for the bulkware production of freeze-dried particles is provided. The drum (302) is in open communication with the vacuum chamber (212) and comprises a main section (304) terminated by a front plate (306) and a rear plate (308), the rear plate (308) is adapted for connection with a rotary supporting shaft (312) for rotary support of the drum (302), and the rear plate (308) is permeable for sublimation vapor from freeze-drying the particles.