Cold Trap Oil Measurement for Ultra-Trace Gas Contamination
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Solution Overview
Problem
Existing methods for measuring trace and ultra-trace oil content in gases, particularly in cryogenic engineering, suffer from narrow measurement ranges, inaccuracy due to varying oil compositions, and potential device contamination, leading to safety risks and operational issues in aerospace and cryogenic systems.
Innovation Solution
A measuring device and method utilizing a liquid nitrogen cold trap enrichment mode to extract oil components into a liquid phase, followed by infrared spectrophotometry for accurate measurement, enabling a wide range of 1500 ppmW to 1 ppbW detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photoelectric effect method is used to measure oil content in helium, then measurement can be performed, but the measurement range is narrow (0-250 ppb) and device contamination occurs when oil content exceeds this range
Solution Approach 1:
The patent changes the measurement parameter from direct gas-phase photoelectric detection to liquid-phase infrared spectrophotometry after cold trap enrichment. This parameter transformation enables measurement across a wide range from 1 ppb to 100 ppm, resolving the narrow measurement range limitation of the original photoelectric method while maintaining high accuracy through standardized liquid-phase analysis.
Solution Approach 2:
The patent introduces a liquid nitrogen cold trap as an intermediary enrichment device between the gas sample and the measurement system. This mediator concentrates trace oil components from large volumes of gas into small volumes of liquid extractant, enabling both ultra-trace detection and preventing overload of the measurement system, thus expanding the adaptable measurement range.
2Measurement precision
If concentration time is extended to detect low oil content, then measurement sensitivity improves, but oil mist overloads the filter screen and contaminates the device
Solution Approach 1:
The patent extracts oil components from the gas phase into a liquid extractant phase using the cold trap. This separation takes the harmful oil mist out of the gas stream before it can contaminate downstream devices, while simultaneously concentrating it into a manageable liquid form suitable for accurate measurement without causing overload.
Solution Approach 2:
The patent converts the harmful effect of oil mist accumulation into a beneficial concentration process. By allowing the cold trap to collect and concentrate oil components that would otherwise contaminate the system, the harmful substance becomes a concentrated sample that can be accurately measured and quantified without causing device damage.
3Measurement precision
If infrared spectrophotometry is used for oil analysis, then accurate quantitative analysis is achieved, but the method requires liquid phase sample preparation from gas phase
Solution Approach 1:
The patent utilizes phase transition as the core mechanism for sample preparation. Liquid nitrogen in the cold trap causes gas-phase oil components to condense and transfer into liquid extractant phase. This automatic phase transition simplifies the complex gas-to-liquid sample preparation process into a single-step physical transformation, maintaining measurement accuracy while reducing operational complexity.
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
Enables reliable and accurate measurement of trace and ultra-trace oil content, identifying pollution sources quickly and effectively, thereby preventing accidents in cryogenic systems and ensuring safety in aerospace applications.
Implementation Method 1
liquid nitrogen cold trap enrichment mode to extract oil components into a liquid phase
Implementation Method 2
liquid nitrogen cold trap enrichment mode
Implementation Method 3
infrared spectrophotometry method can respectively measure the characteristic absorption of methyl, methylene, and aromatic rings
Data Source
AI summary
The present disclosure relates to a measuring method and device for trace and ultra-trace oil content. The measuring device of the present disclosure includes a cryogenic enriching device, an extracting device and an infrared spectrometer; The cryogenic enriching device includes a Dewar container and a U-shaped pipe; The extracting device includes an extractant container, an input pipe, an outlet pipe and an extraction liquid quantitative pipe; A mass flowmeter is further disposed on the U-shaped pipe, the oil content in the gas is calculated according to the measured total mass of the gas and the oil concentration of the extraction liquid measured by the infrared spectrometer. The present disclosure further provides a measuring method, which converts the measurement of oil content in gas into the measurement of oil concentration in liquid extractant through effective extraction by liquid nitrogen cold trap enrichment mode, and adopts infrared spectrophotometry to accurately measure.