Crude oil with low sulfur content ("sweet crude") is coveted because it is more easily processed into usable gasoline. By contrast, sour crude contains a significant H2S concentration and requires more expensive processing. Online H2S analysis is required to determine how much processing a specific feed of crude oil will require and to differentiate crudes by their commercial value.
The composition of oil presents significant challenges to direct optical analysis. These challenges include aromatic hydrocarbons and/or phenols which absorb heavily in the UV range and act as spectroscopic interferents, particulates which scatter light, and the opacity of heavier crudes (too dark to transmit a light signal and will not allow optical analysis).
The OMA H2S in Crude Oil Analyzer combines a high resolution UV-Vis absorbance spectrophotometer with a sophisticated headspace sampling system for highly reliable H2S-in-crude monitoring. This field-proven solution provides extremely fast response in a low-maintenance package.
The system uses a 'headspace' sample conditioner to circumvent the opacity of crude oil and continuously measure H2S concentration in the stream with proven reliability. The operating principle of the system is Henry's Law: part of the liquid sample is evaporated into 'headspace gas'— a vapor-phase sample that is totally representative of the liquid composition and can be analyzed very easily using UV spectroscopy.
The archaic 'paper tape' method for measuring H2S in crude is rapidly being phased out at modern petroleum processing facilities: the lead acetate tape requires frequent replacement as well as special handling/disposal due to the toxicity of the tape. Additionally, tape saturation issues impose limitations on concentration range.
The OMA H2S in Crude Oil Analyzer does not use consumables or moving parts, thus providing a more automated and elegant analysis solution. This system delivers the reliability and fast response needed for tight control in crude oil processing.