Versatile gas analyzer meets refinery application requirements

Density, specific gravity and percent concentration are important gas measurements throughout the crude oil refining process. Conoco-Phillips’ Roxanna and BP’s Texas City are among the refineries using Yokogawa’s GD402 gas analyzer .

Using the tuning fork principle, the GD402’s detector directs a continuous gas sample through a chamber containing a resonating tube. Different sample gas densities allow the resonating tube to vibrate faster or slower, thus gas density is determined by the frequency of the resonating tube.

The vibrating element type, gas measurement does not require reference air, is not effected by the temperature of the sample gas or ambient temperature, is resistant to the common problem of oil misting, and is fast and accurate.

Conoco-Phillips’ Roxanna refinery’s technical analyzer specialist, David Crocket, says, ”The GD402s work better than the products we were using and the specific gravity output provides a good backup measurement to our gas chromatograph BTU measurements.”

BP’s Texas City refinery replaced mechanical gravitometers, which use purely mechanical means to make the measurement, with GD402s. ”The old instrument was a nightmare to maintain, it had too many veins, the belts broke and we were uncertain of the accuracy. The GD402 is believable, and has temperature and pressure compensation,” says BP, Texas City analyzer supervisor Neil McDuffy.

—Dave Harrold, Senior Editor, Control Engineering, dharrold@reedbusiness.com

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