Operations Of On-line Chromatographs

Author: Charlie CookDownload File

Since the early eighties it has become common in the United States, and elsewhere in the world, for natural gas to be bought and sold based on the amount of energy delivered. The quantity of energy delivered is calculated by multiplying the gas volume per unit time by the heating value (BTU) per unit volume. Gas chromatography is normally employed for the calculation of the heating value. However, when the gas chromatograph runs an analysis we not only get the heating value, but other valuable information; such as gas composition and relative density. This additional information is used in the gas volume calculations. Gas Chromatographs (G.C.s) have been widely used in hydrocarbon processing facilities when high quality product specifications are required, or when rigid custody transfer standards are needed for natural gas trading. Gas chromatography is a scientific method in which a gas sample is separated into its component parts for measurement. The gas chromatograph consists of subsystems that inject the sample, separate the sample, detect the components, integrate the peaks, and report the results. The injection, separation, and detection all occur in the heart of the GC known as the GC oven. The integration and calculation of results are done in the controller which can be considered the brains of the system