Freeze-Drying Device Vacuum-Induced Surface Freezing Bumping Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vacuum-induced surface freezing in freeze-drying devices often results in a bumping phenomenon, which scatters and destroys the frozen liquid, leading to variations in the shape and characteristics of the dried material, reducing product quality and yield.
Innovation Solution
A freeze-drying device with a controller that executes an exhaust mitigation process at a depressurization capability less than the rated capability, using a partial pressure value of the medium to determine the end of the process, to minimize shape and characteristic variations in the dried material and improve production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If vacuum-induced surface freezing is performed with rapid depressurization, then freezing speed is improved, but bumping phenomenon occurs causing destruction of frozen liquid and product quality degradation
Solution Approach 1:
The patent applies dynamics by making the depressurization process adjustable and controllable. The vacuum pump's exhaust capability is dynamically regulated during the freezing process, allowing the system to transition from rapid depressurization (for fast freezing) to controlled depressurization (to prevent bumping). This dynamic control resolves the contradiction between freezing speed and product quality consistency.
Solution Approach 2:
The patent changes the pressure parameter during the freezing process. By controlling the degree of depressurization and maintaining pressure within specific ranges, the system prevents the bumping phenomenon while still achieving adequate freezing speed. The parameter change from full vacuum to controlled partial vacuum resolves the contradiction between rapid freezing and product quality.
2Productivity
If rated exhaust capability is used for depressurization, then processing efficiency is improved, but bumping phenomenon scatters and destroys frozen liquid
Solution Approach 1:
The system dynamically adjusts the vacuum pump operation during the freezing process. Instead of maintaining constant rated exhaust capability, the pump's output is modulated based on process requirements. This dynamic adjustment maintains processing efficiency while ensuring freezing process stability by preventing bumping.
Solution Approach 2:
The patent applies beforehand cushioning by controlling the depressurization rate to prevent bumping before it occurs. By regulating the vacuum pump's exhaust capability during critical phases of freezing, the system cushions against the harmful effects of rapid pressure changes that would cause bumping, thus maintaining both efficiency and reliability.
3Loss of time
If rapid depressurization is applied, then freezing time is reduced, but structural boundaries and crystal growth variations are generated
Solution Approach 1:
The patent changes pressure parameters during the freezing process to optimize both time and uniformity. By controlling depressurization to occur at specific stages and maintaining pressure within optimal ranges, the system achieves rapid freezing without generating structural boundaries or crystal growth variations. The parameter changes resolve the contradiction between freezing time and composition stability.
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 solution effectively prevents the bumping phenomenon, ensuring stable crystal growth and consistent product quality by controlling the depressurization process, thereby reducing variations in the dried material's shape and characteristics and enhancing production efficiency.
Implementation Method 1
a freeze-drying device that freeze-dries a liquid using vacuum-induced surface freezing
Implementation Method 2
depressurizing containers filled with a liquid including a raw material and a medium to freeze the liquid from a liquid surface
Implementation Method 3
The heat of a liquid is removed from the container, which is a contact surface, and the entire liquid is finally frozen by the growth of an ice nucleus
Implementation Method 4
the ice nucleus is formed at a position closer to the bottom side in the container than the center, that is, in a lower layer part of the liquid
Implementation Method 5
removes a medium in a frozen material by sublimating the medium without going through a liquid phase again
Data Source
AI summary
A freeze-drying device includes a controller configured to control depressurization of containers filled with a liquid including a raw material and a medium to freeze the liquid from a liquid surface. The freeze-drying device also includes a gas capture pump configured to exhaust a freeze-drying chamber accommodating the containers, and a positive-displacement pump configured to discharge gas from a space accommodating the gas capture pump. The controller executes an exhaust mitigation process that performs the depressurization at an exhaust capability that is less than a rated exhaust capability of the freeze-drying device. The controller uses a partial pressure value of the medium to determine when the exhaust mitigation process ends. The controller maintains an exhaust speed of the gas capture pump and decreases an exhaust speed of the positive-displacement pump in the exhaust mitigation process.