Liquid Nitrogen Lyophilization System for Uniform Freezing
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Solution Overview
Problem
Current lyophilization systems in the pharmaceutical and food industries face challenges such as enzyme degradation, non-uniform product formation due to slow freezing, high energy consumption, and environmental impact from chlorofluorocarbons and rotating equipment, which affect the quality and efficiency of the process.
Innovation Solution
The system replaces hot oil with liquid nitrogen as a heat transfer medium, allowing for rapid freezing outside the lyophilization chamber, reducing the need for rotating parts and cooling the chamber, and optimizing ice crystal formation for consistent product morphology and reduced energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If bulk freezing is used to preserve biological activity, then the product can be stored without freezing equipment, but slow freezing creates concentration gradients that cause cholesterol and triglyceride globules to coalesce and remain non-uniform after dissolution
Solution Approach 1:
The patent applies preliminary action by performing rapid freezing before lyophilization to prevent the formation of concentration gradients and globule coalescence. The liquid nitrogen freezing is conducted in advance to lock in a uniform distribution of cholesterol and triglyceride globules before the drying process, ensuring product uniformity is established prior to storage.
2Ease of operation
If bulk freezing is used to avoid continuous freezing storage, then storage equipment is simplified, but enzyme degradation increases due to slow freezing and concentration gradients
Solution Approach 1:
The patent applies preliminary action by conducting rapid freezing with liquid nitrogen before lyophilization to minimize enzyme degradation. This pre-freezing step is optimized to occur quickly, preventing the slow freezing conditions that cause enzyme degradation, while still achieving the goal of simplified storage without continuous freezing equipment.
3Manufacturing precision
If liquid nitrogen is used for rapid freezing, then product uniformity and enzyme stability are improved, but nitrogen consumption increases
Solution Approach 1:
The patent applies partial action by using liquid nitrogen only for the critical freezing phase before lyophilization, rather than continuous nitrogen cooling. The system uses nitrogen to achieve the necessary rapid freezing for product uniformity, then transitions to atmospheric or controlled conditions during storage, reducing overall nitrogen consumption while maintaining product quality.
4Power
If hot oil is used as heat transfer medium in traditional lyophilization, then heating efficiency is maintained, but rotating equipment and electricity consumption increase along with environmental impact
Solution Approach 1:
The patent applies mechanics substitution by replacing the mechanical rotating equipment and hot oil circulation system with a static liquid nitrogen freezing system. Instead of using mechanical agitators and pumped hot oil, the system uses the phase change and heat transfer properties of liquid nitrogen to achieve freezing without moving parts, thereby eliminating electricity consumption for rotation and reducing environmental impact.
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 approach minimizes nitrogen usage, reduces carbon footprint, and enhances process efficiency with faster cycle times and improved product consistency, while eliminating oil leaks and maintenance costs associated with hot oil systems.
Implementation Method 1
Liquid nitrogen (LIN) based systems are more economical over the long run than cooling with compressors
Implementation Method 2
Sometimes fluorocarbon refrigerants may have a higher boiling point than other liquid refrigerants, for example, liquid nitrogen. A higher boiling point, being closer to the temperature of the solution droplets, results in less of a vapor phase barrier between the particle and the refrigerant. This can result in more rapid freezing of the particles than can be achieved with even colder refrigerants such as liquid nitrogen.
Implementation Method 3
During the next step of the process, hot oil is used to heat shelves within the chamber on which the product is placed so to sublimate water crystals formed on the product as it freezes.
Implementation Method 4
In the lyophilization system disclosed herein, hot oil currently used is replaced with either hot nitrogen or similar specific heat transfer media, depending on the heat duty requirement of the system.
Data Source
AI summary
A process and system for lyophilizing a product. The product is first cooled in a cooling chamber (12) and then passed through a liquid nitrogen bath (14) where it is frozen. It is then freeze dried in a lyophilization chamber (26) during which the water or non-aqueous media is sublimated using a combination of gaseous nitrogen and vaporized nitrogen from liquid nitrogen supplied to the lyophilization chamber. Water and non-aqueous media removed from the product during sublimation is purged from the chamber. The system of the present invention provides more energy efficient operation, eliminates the use of hot oils and oil leaks, operates more reliably, and the liquid nitrogen can be used both as a refrigeration source, for heating shelves instead of hot oil and also can maintain the lyophilization temperature in case of power failure with minimum electric power supply in case of a power outage.