CALGARY, Alberta, Canada, – Galvanic Applied Sciences, Inc. reveals an innovative new control strategy for sulfur recovery units: DOUBLE AIR DEMAND (DAD).

DAD is designed to overcome the limitations of traditional SRU control strategies. Tail gas analysis is inherently insufficient due to long process lag time. Feed forward analysis is prone to interferences and becomes expensive when monitoring multiple acid gas streams.

DAD incorporates two measurements, one at the usual location at the end of the catalytic stage (tail gas), with an additional analyzer located at the outlet of the first condenser. External programmed logic synchronizes the DAD output signals with the acid gas and air flow ratio control. The benefit of using two analyzers is that if one fails or is down for scheduled maintenance, the plant is still controlled automatically.

“The DAD control strategy results in a more accurate and faster response to changes in feed gas composition,” comments Parisa Akhshi, senior portfolio manager. “This minimizes SO2 emissions and optimizes sulfur recovery.”

SRU upsets are easily handled using DAD thanks to the rapid response time. For example, selective oxidation tail gas treating units (TGTU) are bypassed if H2S exceeds limits. Regenerative TGTUs are bypassed if increased SO2 levels are detected from reduction reactor breakthroughs. This leads to plugging, corrosion, and damage throughout the TGTU. Recovering from sour water stripper excursions is even more complicated and requires extensive cleaning and repair activities. Excessive downtime forces reduced upstream capacity in hydrocarbon processing units.

Implementing DAD requires an air demand analyzer to handle the difficult upstream conditions present at the outlet of the first condenser. Sulfur vapor is five times higher and the sample temperature is significantly greater compared to the tail gas. In order to successfully operate at this location, robust sample handling is critical. The following factors greatly contribute to the success of an installation after the first condenser. 

  • Close-Coupled Mounting: Minimizes sample transport time to prevent plugging associated with extractive installations.
  • In-Line Condensing: Sulfur handling within the process avoids plugging issues associated with an externally condensed sulfur method.
  • Sample Probe Cooling: Instantly adjusting the cooling medium according to changing conditions to maintain a consistent, and efficient sulfur knockout temperature.
  • Electric Oven: Ensures the oven temperature remains above sulfur dew point without the need for medium or high-pressure steam.
  • Back-Purge: Clears out the sample path and vent path for rapid recovery from any excursion to avoid downtime.

There is only one model of tail gas analyzers that meets these criteria: Brimstone™. “DAD is only possible thanks to the robust sample system of our Brimstone™ tail gas analyzer,” comments platform manager, Dennis Hnidan. “The analyzer’s sealed fiber gland and purged enclosure also helps protect against corrosion from high sulfur vapor.”

Brimstone™ performs a broadband UV analysis covering 530 pixels from 200 to 400 nm. This ensures effective interference compensation when measuring H2S, SO2, COS, and CS2. Monitoring COS and CS2 provides operators with trending for catalyst condition and conversion efficiency.

“Galvanic has been supporting the process gas industry for over 40 years. The DAD control strategy provides measurement certainty by offering the best response time to SRU operators,” comments David Haydt, director of research & development.

Keywords: DAD, Double Air Demand, Air Demand, Tail Gas, SRU, Sulfur Recovery Unit, Brimstone

Applications: Refinery, Natural Gas Processing, Sulfur Recovery

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David Haydt

When it comes to solving complex applications challenges for customers, David Haydt has built his stellar reputation as the “go-to guy” over his 28-year career at Galvanic. Dave joined the company in 1993 as an applications technician at Galvanic’s Calgary headquarters. From 1999 to early 2006, he served as a field-service technician based out of Houston, Texas, providing start-up assistance, field repair service, and training to Galvanic’s natural gas transmission, petrochemical and refining industry customers. In 2006, he was promoted to production manager for Galvanic’s gas-analysis products, overseeing all aspects – from design and development of tailored systems to meet the customer’s specific application needs to ensuring on-time delivery of products. In 2015 Dave assumed the role of R&D/applications manager, where he became responsible for Galvanic’s entire line of gas- and liquid-analysis products. In 2021 Dave was promoted to Vice President of Product Innovation. Dave is accountable for the evolution of Galvanic’s entire product portfolio.

Dave started his career as a laboratory analyst for Norwest Laboratories in Alberta, Canada. He holds a bachelor of science degree in chemistry from the University of Calgary.

Steve Aasen

An operations-focused executive with 20+ years of experience driving financial performance in technology-based multi-national companies, Steve Aasen joined Galvanic in late 2014 as director of finance. He came to Galvanic from General Dynamics Canada, Ltd, one of Canada’s largest and most-established defence system integrators, where he served for eight years as director of finance. Earlier, Steve was at Telvent North America, a leading Calgary-based IT and industrial-automation provider for pipeline and energy-utility companies. He started as divisional controller and ultimately served as the company’s chief financial officer. Steve received a bachelor of commerce degree in accounting from the University of Saskatchewan, in Saskatoon, Saskatchewan, Canada. He also earned a CMA Designation from the Society of Management Accountants.

Rene Aldana

A senior business executive with more than 20 years of management experience in the global oil & gas industry, Rene Aldana joined Galvanic as its CEO in June, 2018. Rene has extensive experience in strategic leadership, process automation, talent development, and M&A integration that will benefit the next chapter of Galvanic’s growth and progress. Before coming to Galvanic, Rene was the chief operating officer for ZCL Composites Inc., a TSX-listed composites manufacturing company serving the petroleum, water, and waste water industries. Previously, he was the managing director for Yokogawa Canada, a world leader in industrial process measurement and automation solutions. For 18 years prior, he served in a series of high-profile positions at Telvent, starting in customer service, followed by engineering project management, and culminating as vice president of its International Oil & Gas division. He has a bachelor’s of science in computer science from the Simon Fraser University in Canada, an executive MBA from the IE Business School in Spain, and an ICD.D designation from Canada’s Institute of Corporate Directors. Rene is fluent in English, Spanish (native), and Portuguese.