Sampling analysis is a very critical part in petrochemical and other industries. Obtaining correct analysis results requires operators to carry out standardized operations step by step according to the standard operation process of the sampling system, and more fundamentally, and more importantly, the design of the sampling system requires to ensure that representative samples are obtained.
At present, the main off-line sampling method is to set up a branch sampling line on the process line to direct the medium into the sampling container, then bring the container to the analysis laboratory, and connect the analyzer for qualitative and quantitative analysis of medium components. As far as we know, many enterprises still use open sampling methods, as shown in Figure 1 below. The structure of open sampling is simple; just open the sampling valve to get the sample. But the drawbacks are also very obvious, such as the medium residues inevitably remain at the end of the sampling line, and the medium may react with the air or some components volatilize (which may be toxic and harmful), it is difficult to clean up after long-term sampling and pollutes the environment. Therefore, representative samples cannot be obtained, and the analysis results cannot represent the actual medium situation in the current line.