APC - Sulfur Removal

A tailored application for Sulfur Removal Units

The SRU advanced control package uses Axens' latest generation multivariable controller MVAC.

It is designed to achieve optimum operation of the SRU, often a difficult to control process, in an environment with frequent composition and flowrate variations of the multi-component feed.

Poor operation can easily result in emission violations, SRU shutdown or costly constraints for upstream plant operations.

As a catalyst manufacturer and an advanced control technology supplier, Axens combines all the necessary expertise for successful SRU APC projects.

A four-step control strategy

• Tail gas ratio control: H2S / SO2, by adjustment of air flow for optimal conversion
• Catalytic reactor inlet temperature control, to monitor hot spots, control catalyst bed dew-point and prevent sulfur laydown on the catalyst
• Thermal reactor temperature control, by adjustment of the feed split, to promote complete oxidation of amine compounds in the acid gas feed
• Compensation for dead time variation, generated by significant changes in the flowrate.

On-line analyzers are recommended for tail gas and acid gas in order to allow feed-back and feed-forward actions.

Axens' inferential technology is used for on-line estimation of main fractionator product qualities.

Benefits

• Reduction of sulfur compounds emissions (meet emissions limits)
• Reduction of operating problems (sulfur blockage,…)
• Reduction of unscheduled downtime (constraints for upstream units)
• Increase of sulfur recovery ( + 2%)
• Extended catalyst bed life
• Reduction of energy consumption