The volume of the gas decreases after sampling
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The company schedules weekly safety analyses at several fixed locations; one of these is a steam condenser from which hot gas emerges. Each time, a 100ML sample is collected using a glass syringe, and after the syringe cools down, its volume drops to around 30ML. Here’s the question: when calculating the result, it is sample peak area/standard sample peak area * concentration of the standard gas. For example, if the result is 9%, is it necessary to divide this value by (100/30)?
No, mass is conserved; the mass of gas and liquid is the same.
This sampling leads to such problems; it’s better when the composition is relatively simple. Often, the components in the sample are not uniform, which results in different percentages for various components. I think this one should be divided; since the volumes are different, the results will vary
It’s not necessary; the percentage is a relative value
It is necessary to consider how the reduced cooling volume is formed, and whether water vapor in the sample of the vapor condenser condenses into liquid water; if so, it is equivalent to increasing the sample concentration.
The volume of the gas used for analysis should be measured in standard liters.
Bro, figure out whether it’s a standard gas; take samples according to standard gases
This needs to be determined based on the requirements of the analysis and the actual sample conditions; it shouldn’t be such an easy decision to make. Since it is a sample with a high temperature and containing condensate, the analysis requirements need to take into account the reduction in volume caused by condensation; this volume reduction is significant. However, as the amount of condensate is small (70 milliliters of condensate, which is approximately 50 mg of water), this amount of condensate will adhere to the walls of the sampling container. At this point, if the components in the remaining gas are not dissolved into these condensates, their concentration increases by about three times. And if some components of the gas are dissolved in the condensate, it is also necessary to take into account the actual relationship between solubility and the condensate in order to calculate the volume that these soluble components would have occupied before condensation. If you are analyzing the condensate and the components dissolved in it, the sample amount you have may not be sufficient for a valid analysis. This is a very specific question, and it is necessary to judge based on factors such as how your analysis methods and indicators are defined.
This post was last edited by qugd on 2017-3-13 at 13:44. However, the units of concentration are sometimes related to volume; mass is conserved, but is volume also conserved? In particular, gases that can be compressed and gases that can be condensed.
Dear experts, I still don’t understand how to take samples from hot gas samples and how to analyze them