Ethylene Oxide Recovery Through Pressure-Controlled Selective Condensation
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Solution Overview
Problem
Existing sterilization systems using ethylene oxide (ETO) face challenges in recycling low concentration ETO gas mixtures due to reduced effectiveness and the need for high-pressure vessels, which are costly and risky, while current disposal methods pose safety hazards and environmental concerns.
Innovation Solution
A system and method for recovering ETO by reducing pressure, condensing water vapor, and elevating ETO boiling point to separate and condense ETO into a liquid, using minimal moving parts and maintaining operations below atmospheric pressure to prevent leaks and explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low concentration ETO gas mixtures are used for sterilization, then the relative non-flammability allows for recycling, but the sterilization effectiveness is reduced
Solution Approach 1:
The patent changes the concentration parameter of ETO gas from low (recyclable, safe) to high (effective sterilization) through a concentration process. The system recycles low concentration ETO gas by removing inert gases and water vapor, then concentrates the ETO to high levels suitable for effective sterilization while maintaining safety through controlled concentration rather than high pressure
Solution Approach 2:
The patent extracts inert gases (nitrogen, carbon dioxide) and water vapor from the low concentration ETO gas mixture through condensation and separation processes. This extraction purifies the ETO gas by removing diluents, enabling concentration of the sterilizing agent without requiring high-pressure vessels
2Productivity
If high concentration ETO gas is used for effective sterilization, then the sterilization effectiveness is improved, but the gas is extremely flammable, toxic, and explosive
Solution Approach 1:
The patent changes the concentration parameter from low to high through a controlled concentration process that removes inert gases and water vapor. By concentrating ETO through phase change and separation rather than compression, the system achieves high sterilization effectiveness while maintaining safety through atmospheric pressure operation
Solution Approach 2:
The patent uses condensation temperature differences as an intermediary mechanism to separate ETO from inert gases and water vapor. The selective condensation process allows safe handling of high concentration ETO by controlling the phase change process rather than relying on high-pressure containment
3Reliability
If low concentration ETO gas mixtures are recycled, then the safety is improved, but high-pressure vessels are required which are more expensive and carry leakage risk
Solution Approach 1:
The patent changes the pressure parameter from high to atmospheric pressure by using phase change and separation processes. Instead of compressing low concentration ETO gas to high pressure for concentration, the system uses condensation and evaporation at atmospheric pressure, eliminating the need for high-pressure vessels and associated safety risks
Solution Approach 2:
The patent replaces the mechanical compression system (high-pressure vessels and compressors) with a thermal process system (condensers, evaporators, and separators). This substitution uses temperature and phase change mechanisms instead of mechanical pressure, simplifying the equipment and reducing costs while maintaining safety
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 system efficiently recovers high-purity ETO for reuse, minimizing waste and reducing operational risks by leveraging differences in vapor pressures and boiling points, ensuring safe disposal of nitrogen and water, and avoiding the need for absorption materials.
Implementation Method 1
a pressure reducing throttling valve for reducing and maintaining a pressure of a waste gas from one or more sterilization chambers to a first predefined pressure of 0.069 bar
Implementation Method 2
A first condenser is configured to receive the gaseous mixture via the pressure reducing valve, and to cool the gaseous mixture to a temperature below a boiling point temperature and above a freezing point temperature of the water vapor at the first predefined pressure
Implementation Method 3
A separation pump coupled to the first tank raises the pressure of the gaseous mixture to a second predefined pressure
Implementation Method 4
A second condenser is configured to receive the gaseous mixture from the separation pump, to cool the gaseous mixture to a temperature below a boiling point temperature and above a freezing point temperature of the sterilization agent at the second predefined pressure causing the sterilization agent to condense into a liquid
Data Source
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AI summary
A system for recovering a sterilization agent may include a pressure reducing value for reducing a pressure of a waste gas from a sterilization chamber to a first predefined pressure. The waste gas may include a gaseous mixture of a sterilization agent, nitrogen gas, and water vapor. A first condenser may cool the gaseous mixture to below a boiling point temperature and above a freezing point temperature of the water vapor at the first predefined pressure. A first tank may store the condensed water vapor. A separation pump may raise the pressure of the gaseous mixture to a second predefined pressure. A second condenser may cool the gaseous mixture to below a boiling point temperature and above a freezing point temperature of the sterilization agent at the second predefined pressure causing the sterilization agent to condense into a liquid. A second tank may store the separated sterilization agent.