Hydrogen Recycle Analysis


Application Summary

Analysis Point Analyte Typ. Range Suitable Analyzer
hydrogen H2S 0-10 ppm OMA H2S Analyzer

Measuring Hydrogen Sulfide in Hydrogen Recycle

In one part of the petroleum refining process, low-octane naphtha is converted to high-octane 'reformates,' which can then be used to increase the octane of fuel blends. This process occurs in the Catalytic Reforming Unit, where various reactions consume the naphtha feedstock and produce more complex hydrocarbons including aromatics.

These reactions remove hydrogen atoms from the hydrocarbon molecules, thus producing large amounts of H2 gas which gets stripped out of the reformates stream in a hydrogen separator. The recovered 'hydrogen recycle gas' is a valuable utility for many processes, including mixing back into the naphtha feedstock to the Catalytic Reforming Unit. (While hydrogen is a byproduct of the catalytic reforming reactions, it is also necessary in the feed to hydrocrack paraffins and protect the catalyst from polymer formation.)

Use of the H2 recycle gas is complicated by the formation of H2S in the reformer if the naphtha feedstock is not completely desulfurized. Catalysts are poisoned by exposure to H2S, especially the platinum- and rhenium-containing catalysts commonly used in the Catalytic Reforming Unit. To protect the catalysts and reduce reforming inefficiency, a method of monitoring the H2S in the hydrogen recycle gas is required.

The OMA H2S Analyzer uses a high-resolution UV-Vis spectrophotometer to measure real-time H2S concentration in the hydrogen recycle gas stream. This measurement is an ideal application for the OMA because the hydrogen background has no absorbance in the UV wavelength domain. Additionally, the OMA is built for direct measurement of the hot, high-pressure sample in the rugged optical flow cell, allowing for a simpler sample handling system.