Applied Analytics TLG-837 Tail Gas / Air Demand Analyzer

Overview

The Applied Analytics TLG-837 is a continuous UV-Vis tail gas and air demand analyzer purpose-built for the Claus sulfur recovery unit (SRU) of a refinery or gas plant, simultaneously measuring hydrogen sulfide (H2S), sulfur dioxide (SO2), carbonyl sulfide (COS), and carbon disulfide (CS2) in the tail gas stream to keep the Claus reaction stoichiometry on target. Rather than drawing a hot, corrosive, and potentially explosive sample gas into the analyzer electronics, the TLG-837 uses a patented in-situ DEMISTER probe and fiber-optic light transmission to take the measurement directly at the process, feeding back an accurate air demand signal that lets the SRU control loop hold the optimal 2:1 H2S-to-SO2 ratio and maximize sulfur recovery efficiency.

Working closely with plant engineers in the region, Seven Star LLC proudly supplies the TLG-837 to refineries and gas processing plants across the Sultanate of Oman and the wider GCC. Every unit supplied through Seven Star LLC comes with manufacturer calibration documentation and access to regional technical support.

Operating Principle

The Applied Analytics TLG-837 identifies and quantifies tail gas composition using dispersive ultraviolet-visible (UV-Vis) absorbance spectrophotometry. A pulsed xenon light source with an approximate five-year service life transmits light through fiber optic cables – standard length 4 meters, extendable up to 6 meters – to the in-situ probe head, where the sampled tail gas interacts with the light according to its current chemical composition before the signal returns to a nova II diode array spectrophotometer covering the 200–800nm spectral range. Because H2S, SO2, COS, and CS2 each produce a distinctive absorbance curve, a deconvolution algorithm separates the total sample absorbance into individual analyte concentrations by solving a regression matrix built from hundreds of calibration data points, rather than relying on a single fixed wavelength or a mechanical filter wheel.

The patented DEMISTER probe design uses low-pressure steam to control probe temperature and selectively condense sulfur vapor out of the sample path, while an aspirator creates a Venturi effect that continuously circulates fresh tail gas across the optical flow cell. Because light – not the hazardous sample – travels to the analyzer enclosure, no toxic or explosive process gas ever enters the electronics housing, allowing the TLG-837 to operate outdoors without a shelter and without sample lines, heat tracing, or moving parts of any kind. The practical result is a 1-to-5-second response time, a repeatability of ±0.4%, and an off-ratio measurement range spanning 100:1 to 1:20 H2S/SO2 – wide enough to track an SRU through upset conditions as well as steady-state operation.

Engineering Design of the Applied Analytics TLG-837

The TLG-837 analyzer enclosure measures 610 × 508 × 203mm and weighs 15kg, built from NEMA 4X (IP66-rated) stainless steel to withstand the outdoor, corrosive environment surrounding an SRU tail gas line. The companion probe assembly measures 914 × 305mm and weighs 13kg, with wetted materials of 316/316L stainless steel and Kalrez selected specifically for resistance to sulfur compounds and Claus process conditions. Fiber optic cables carry the xenon light signal between the analyzer housing and the probe head, physically separating the electronics from the hazardous sample point by several meters.

Because SRU tail gas lines frequently sit within a classified hazardous area, Applied Analytics offers the TLG-837 platform in certified configurations built on the same optical bench and DEMISTER probe technology as the standard unit. The TLG-837-ATEX configuration adds ATEX flameproof (Ex d) hazardous-area certification for European and GCC-aligned installations, while the TLG-837-ATEX-IECEx-EXP-H configuration layers IECEx certification onto the same Ex d flameproof enclosure design for operators who require both ATEX and IECEx approval on a single unit – EAC, PESO, and JPN certifications are also available by inquiry. Because all three configurations share the identical measurement principle, probe design, and wetted-parts specification, they are ordered as certification options against the same Applied Analytics TLG-837 base platform rather than as separate analyzer families, and Seven Star LLC’s instrumentation division confirms the exact certification code required for a given hazardous-area classification before quoting.

Key Features

The Applied Analytics TLG-837 delivers refinery-grade tail gas analysis with a safety-first optical design. Its principal capabilities include:

• The Applied Analytics TLG-837 simultaneously measures H2S, SO2, COS, and CS2 in Claus process tail gas using dispersive UV-Vis absorbance spectrophotometry.
• A patented in-situ DEMISTER probe removes sulfur vapor from the sample path using steam-controlled condensation, eliminating the need for external sample conditioning.
• Fiber-optic light transmission keeps toxic and explosive tail gas entirely outside the analyzer electronics enclosure, allowing safe outdoor installation without a shelter.
• The totally solid-state design has no moving parts, sample lines, or heat tracing, minimizing maintenance and eliminating common failure points of legacy tail gas analyzers.
• A wide off-ratio measurement range of 100:1 to 1:20 H2S/SO2 with 1-to-5-second response time tracks the SRU through both steady-state and upset conditions.
• NEMA 4X (IP66) stainless steel analyzer housing and 316/316L stainless steel and Kalrez wetted probe materials withstand harsh, corrosive outdoor refinery environments.
• The Applied Analytics TLG-837 is available in ATEX Ex d and combined ATEX-IECEx certified configurations on the same platform for installation directly within a classified hazardous area.
• Standard 4-20mA analog and digital relay outputs are supplemented by optional Modbus TCP/IP, RS-232/RS-485, Fieldbus, and HART connectivity for direct DCS integration.

Industrial Applications

Refineries and gas processing plants across Oman rely on the Applied Analytics TLG-837 to hold Claus process sulfur recovery units at their target H2S/SO2 stoichiometric ratio, calculating the air demand control signal – derived from the formula (2[SO2] – H2S) × scaling factor – that keeps the reaction furnace and catalytic converter stages operating at maximum sulfur recovery efficiency. Beyond the primary tail gas measurement point, process engineers also deploy the Applied Analytics TLG-837 platform for sulfur pit headspace monitoring, tracking H2S evolution from molten sulfur storage to protect personnel and meet environmental permit limits, and for custom monitoring points identified during a refinery’s own hazard and operability review.

With fast quotation turnaround and technical support, Seven Star LLC supplies the Applied Analytics TLG-837 – including its ATEX and ATEX-IECEx certified configurations – to refineries and gas plants throughout Muscat, the Sohar Refinery and Petrochemical Complex, the Salalah Free Zone, and processing hubs across the wider GCC. Regional maintenance teams depend on Seven Star LLC not only for the initial analyzer supply but for spare DEMISTER probes, fiber optic assemblies, and factory-backed calibration support that keep an SRU’s tail gas control loop running reliably across a multi-unit refinery in Oman and neighboring GCC states.

Technical Specifications

The table below summarizes the principal specifications of the Applied Analytics TLG-837 tail gas / air demand analyzer.

Request a Quote for Applied Analytics TLG-837 Tail Gas / Air Demand Analyzer

Refinery and SRU process engineers evaluating the Applied Analytics TLG-837 – in standard, ATEX, or combined ATEX-IECEx hazardous-area configuration – are invited to submit a formal RFQ through Seven Star LLC’s instrumentation division. With engineering support in Muscat, Seven Star LLC sources spare probes and fiber assemblies for customers in Oman and the GCC, provides full technical datasheets on request, and coordinates calibration and certification support directly with the manufacturer. Contact the Seven Star LLC instrumentation team today to confirm the correct certification code for your hazardous-area classification, request the complete Applied Analytics TLG-837 datasheet, and request a quotation for supply across Muscat, Sohar, Salalah, and the wider GCC region.

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