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

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

Poor operation can easily end up with emission violations, SRU shutdown, or costly constraints for upstream plant operation.

As a catalyst manufacturer and 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 times variation, generated by significant changes in the flowrate.

On-line analyzers are recommended for tail gas and acid gas, in order to permit 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