What causes inaccurate measurements by online analyzers?
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As the title suggests, what factors can affect the accuracy of measurements?
Inaccuracies can occur if syngas sampling is done through the lines of online analyzers; a high solid content in the syngas or improper instrument settings can also lead to inaccurate measurements
So what if, for some reason, the system experiences pressure fluctuations?
The effects caused by fluctuations in the system should not be considered as measurement inaccuracies. In online analysis, the gas to be analyzed passes through the chromatography column of the analyzer, and measurements are taken based on the retention time of different gas components; retention time is therefore a factor that plays a role here. If the system experiences frequent fluctuations, I think the results of online analysis are not very meaningful
The sampling tube is blocked; replace the carrier gas, etc
Can fluctuations in the system cause errors in measurements? Online analysis of vaporization is done using mass spectrometry, right? Our instrumentation technicians say that any fluctuations in system pressure can cause discrepancies between the measured values and the actual values; when such fluctuations occur, it’s necessary to have the instrumentation technicians handle the issue.
There are many reasons why gas analyzers may give inaccurate readings. First, the impurities present in the gas sample being analyzed can affect the analyzer; therefore, preprocessing is required to remove these impurities, such as water, temperature, pressure, dust, and other factors. II. Online gas analyzers tend to experience drift over time; it is generally recommended to calibrate them every 3 months (using standard gas). III. Factors such as the accuracy of the analyzer’s sensors, etc~~~
Currently, online analysis in domestic gasification units is generally carried out using infrared spectroscopy (with the exception of Guotai). Such instruments measure a certain volume flow rate during testing, and this flow rate is usually controlled by a pressure reducing valve that is adjusted manually. When the system pressure changes, it causes variations in the amount of gas entering the analyzer, leading to analysis errors. Therefore, when pressure fluctuates frequently, the data from online analysis is practically meaningless
In fact, after the installation of the online analyzer, fluctuations in system pressure have almost no effect on the analysis; multiple stages of pressure reduction are carried out before sampling, and pressure stabilizing valves are installed before the sampling point. As a result, when system pressure fluctuates, the pressure at the inlet of the online analyzer remains largely unaffected. As for the situation mentioned on the second floor, it is because the analysis sampling points are located at the inlet of the online analyzer; when sampling takes place, the volume of gas entering the online analyzer decreases, which leads to sampling fluctuations and significantly affects the measurement of component concentrations. A small suggestion for the original poster: it’s better to present your main question in a more complete form, rather than throwing out one after another.
Process gas containing water leads to water in the sampling pipeline, which results in inaccurate analysis; this is a common issue, especially in winter
This post was last edited by shanxg on 2010-7-5 at 17:38. 1. Clogging or leakage in the sampling tube results in too small a sample volume. 2. Fluctuations in the sample gas or changes in actual operating conditions. 3. If chromatography is used, it is necessary to check the carrier gas pressure and flow rate. 4. Zero drift occurs over time due to prolonged use. 5. Severe water content in the sample gas. I’m not very familiar with mass spectrometers, so I hope to learn more about them as well