Analysis of liquefied gases
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Our company wants to analyze the composition and content of heavy hydrocarbons in the heavy hydrocarbon tank, but we’re not sure how to take samples and conduct the analysis I’d like to ask everyone! Thank you!
It depends on how heavy your heavy hydrocarbons are. If it is liquefied gas, then the question arises of whether to analyze the gas phase or the liquid phase This also relates to the issues of sampling methods and sampling equipment. Because such medium containers are all under pressure. If it is an oil with low volatility, it is sufficient to simply use the liquid-phase sample.
Reply to 2# qugd: Should the layering phenomenon be taken into account when taking liquid samples from heavy hydrocarbon tanks, and how can it be avoided? Thank you!
This is a rather tricky issue; our laboratory uses gas analysis methods for such tests. In my opinion, 1) sampling from the steel cylinder ensures that the sample is complete, with no loss or evaporation of any substances. 2. Perform chromatographic analysis to determine the content of recombined components in the gas sample. 3. After the steel cylinder comes to rest, release the gas sample and measure the remaining amount of recombined components using weighing. 4. Calculate the total amount.
This analysis is quite complex; it involves two steps, gas phase and liquid phase – it’s tricky to learn.
Reply to 3# yix2321: Hydrocarbon mixtures are miscible; there is no such thing as separation into layers. Unless there is an insoluble phase in the tank from which the sample was taken, and your sampling location happens to be at the layer boundary. To obtain samples from the stratified layers requires a very high level of skill.
Reply to 6# qugd: I conducted repeated sampling analyses and found that by taking only the gas phase, the analysis results for ethane and propane were high. After extracting the liquid phase and performing vaporization analysis, the levels of ethane and propane are much lower; I’m not sure why
In this device, the gas phase is used for safety monitoring and analysis, while the liquid phase is used for quality data. The sampling tank should take the liquid phase.
Reply to 7# yix2321: This is a normal analysis result. If it does not follow this pattern, it indicates that there must be an issue with the analysis or sampling. For liquefied gas, it is a fundamental principle of physics that the gas phase contains a high proportion of light components, while the liquid phase contains a high proportion of heavy components.
Reply to 9# qugd: Thank you. I’m new to LPG analysis and need to learn more!*
Reply to 7# yix2321: At room temperature, ethane and propane have high vapor pressures; ethane generally does not liquefy, and a large portion of propane also does not liquefy. Therefore, the gas phase has a high content of ethane and propane.