The fundamental chilled mirror technique relies on a process of cooling a mirrored surface in contact with gas stream. In the case of HCDP in natural gas, the heaviest molecular weight trace components in the composition condense to form a liquid film when the gas is cooled. The term dew point is most applied to the temperature at which water vapour condenses when atmospheric air is cooled dew or frost forms and becomes visible at this temperature.
Fundamental chilled mirror (manual chilled mirror instruments): Techniques or methods that are widely accepted to measure hydrocarbon dew point (HCDP) or hydrocarbon liquid drop-out. What techniques are used to measure hydrocarbon dew point, and which is ideal?Īs stated above, fundamental chilled mirror analysis, and equation of state calculation from composition using a process gas chromatograph (often used in labs), are the commonly used In conclusion, the measured dew point is dependent on the analytical method, and it is suggested that any reported dew point should therefore be appended with the information on the analytical method used. Other factors such as cooling rate, trigger point, and cell construction directly related to the operation of MCMI and ACMI could also affect HCDP measurement. However, the study claimed that the results from the samples could have been influenced by factors such as the complex nature of the real mixtures which actual state is difficult to be determined by gasĬhromatography. It is suggested that hydrocarbon species (components) could be under-measured, not detected, or misidentified, which has a significant effect on the calculated hydrocarbon dew point. The ACMI samples are greater than those from process GCs. The study found that the dew point measured by the ACMI is greater than that measured by the MCMI. When compared with process gas chromatograph, the study also found that the dew points measured by
Dew point definition manual#
Results for the study were obtained from six samples using one automatic chilled mirror instrument (ACMI), one manual chilled mirror instrument (MCMI), two laboratory gasĬhromatographs (GCs), and two process gas chromatographs (GCs). The report outlined the results of a study that compared the conduct of direct and indirect methods forĭetermining the hydrocarbon dew point of real and synthetic natural gases. That a true value of hydrocarbon dew point is difficult to measure and define.Ī report by the National Physical Laboratory compares several methods for measuring hydrocarbon dew point of natural gas to determine whether gas can be transported safely through nationalĪnd international pipelines in the UK to ensure the final product meet quality standards.
While some techniques have proven to be more efficient than others, the final approach to be used for the measurement of HCDP may be dependent on the application as results in most methods have shown There might not be an ideal way to measure Hydrocarbon dew point as it is not an easy parameter to accurately determine due to several factors that may affect the measurement process.ĭirect measurement by fundamental chilled mirror analysis, and equation of state calculation from gas composition using a process gas chromatograph, are techniques that areĬommonly used across different applications to measure Hydrocarbon dew point (HCDP).
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