Oxygen liquefaction process
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Solution Overview
Problem
Existing methods for liquefying oxygen and argon gas struggle with controlling temperature and pressure fluctuations, leading to inefficient production and potential evaporation, especially when using liquefied nitrogen as a refrigerant, and are not well-suited for intermittent demand scenarios.
Innovation Solution
A liquefaction apparatus with a heat exchanger that includes adjustable cooling and condensing areas, controlled by differential pressure gauges and valves, allows for stable temperature control of liquefied products using liquefied nitrogen, and incorporates bypass lines to adjust temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oxygen gas is cooled with liquefied nitrogen in a heat exchanger, then oxygen can be liquefied, but the liquefied oxygen may be overcooled due to differences in physical properties between the two substances
Solution Approach 1:
The heat exchanger is divided into two distinct sections: a cooling and condensing area (1a) and a subcooling area (1b). This segmentation allows independent control of cooling intensity in different zones, preventing overcooling by limiting the subcooling area's exposure to the coldest refrigerant while still achieving adequate cooling in the condensing area.
Solution Approach 2:
Different sections of the heat exchanger are assigned different functions with different thermal characteristics. The cooling and condensing area (1a) is positioned to receive warmer refrigerant for gentle cooling, while the subcooling area (1b) receives colder refrigerant for additional cooling only if needed. This local differentiation of thermal quality prevents uniform overcooling throughout the entire heat exchanger.
2Device complexity
If a single heat exchanger is used to cool and condense oxygen gas, then the equipment configuration is simple, but it is difficult to control the cooling, condensation, and subcooling processes stably
Solution Approach 1:
The single heat exchanger is functionally segmented into a cooling and condensing area (1a) and a subcooling area (1b), allowing independent control of each process stage. This functional segmentation within a single physical unit maintains equipment simplicity while enabling stable control of different thermal processes through separate flow path management.
Solution Approach 2:
The system dynamically adjusts the flow distribution between the cooling and condensing area and the subcooling area based on real-time process conditions. By making the heat exchanger's functional allocation dynamic rather than fixed, the system can adapt to varying oxygen flow rates and maintain stable cooling, condensation, and subcooling processes even with simple equipment.
3Adaptability or versatility
If oxygen gas flow rate is not stable (as with by-product oxygen), then liquefaction can proceed with available equipment, but temperature and pressure control becomes difficult
Solution Approach 1:
The heat exchanger system dynamically reallocates its cooling capacity between the cooling and condensing area (1a) and the subcooling area (1b) in response to varying oxygen flow rates. When flow rate increases, more refrigerant is directed to the condensing area; when flow rate decreases, subcooling capacity is reduced. This dynamic adaptation maintains temperature and pressure control precision despite variable input conditions.
Solution Approach 2:
The system changes operational parameters (refrigerant flow distribution, heat transfer area utilization) in response to varying oxygen flow rates. By adjusting which heat transfer area is actively used and at what intensity, the system maintains optimal temperature and pressure control across a range of flow conditions without requiring complex additional equipment.
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 apparatus efficiently produces liquefied oxygen and argon at stable temperatures, reducing thermal energy waste and pressure fluctuations, thus improving the efficiency and cost-effectiveness of the liquefaction process.
Implementation Method 1
a heat exchanger (1) whereby a gas (oxygen gas or argon gas) can be cooled and condensed with a refrigerant (such as liquefied nitrogen)
Implementation Method 2
a differential pressure gauge (102) for measuring the difference in pressure between the hot and cold ends of a path through which flows the gas to be liquefied
Data Source
AI summary
An oxygen liquefaction apparatus may include a heat exchanger that allows oxygen gas to be cooled and condensed with liquid nitrogen. The oxygen liquefaction apparatus may include: a differential pressure gauge that measures the difference in pressure between the hot and cold ends of an oxygen flow path; and an oxygen control unit that calculates the level of oxygen inside the heat exchanger based on the differential pressure gauge reading, that controls an oxygen control valve to adjust the level, and that controls the heat transfer area to control the condensation of the oxygen.