Measuring H₂S/H₂ in a Tail Gas Treatment Units (TGTU)

Introduction

The purpose of a tail gas treatment unit (TGTU) is to maximize the conversion of sulfur compounds to H₂S. With an efficiently run TGTU, sulfur recovery efficiency can be increased up to 99.99%.

A Sulfur Recovery Unit (SRU) is responsible for converting most of the sulfur-containing compounds into elemental sulfur, but after the SRU up to 5% of sulfur-containing compounds may remain. The stream that leaves the SRU is known as “tail gas”, and is the feed stream for the TGTU. The sulfur compounds that are still contained within the tail gas are converted by the TGTU into H₂S using a catalytic hydrogenation reduction stage and an amine absorber. The treated gas is then directed to an incinerator, and the rich amine may be directed back to the SRU.

The purpose of making the H₂S & H₂ measurement is to validate the reduction reaction. In addition, the H₂S measurement is also used to identify the sulfur load heading to the amine absorber. The OMA-300 Process Analyzer continuously outputs both H₂S and H₂ readings, providing new measurements approximately every 5 seconds.

System Benefits

• Continuously measures H₂S and H₂ level in TGTU using UV-Vis spectrophotometer
• Totally solid-state build with no moving parts — modern design for low maintenance
• Ultra-safe fiber optic design eliminates the need to bring sample fluid inside analyzer unit
• One-time calibration at factory or site. No need for re-calibration

Diagram of a Typical Tail Gas Treatment Process

In the diagram below, the tail gas treatment units analysis point is identified by AT8.

H₂S and H₂ are measured at AT8 in the stream leaving the TGTU, before being sent to the amine absorber.

Installation and Product Photos

Further Reading