Selection of an appropriate and cost effective Tail Gas Treatment process to follow existing Claus plants is a challenge facing refiners and natural gas plant owners around the world. New emission regulations, interest in increasing sulfur recovery and processing of higher sulfur crudes are the main drivers. The most common approach is to install an amine-based Tail Gas Treatment Unit (TGTU), however, lower installed cost and higher reliability can be achieved by combining two well established processes, Jacobs’ SUPERCLAUS® process and MECS’ DynaWave® wet gas scrubber technology. This combination costs less to install, is less expensive to operate and to maintain, requires a smaller footprint, greatly simplifies overall operation and has a greater on-stream reliability when compared to an amine-based
By combining the SUPERCLAUS® and DynaWave® technologies, the overall system can achieve greater than 99.9% sulfur removal at compelling capital and operating costs. Approximately 99.0% of the H2S is captured and recovered as elemental sulfur by the SUPERCLAUS® and the remaining sulfur is scrubbed and converted to Na2SO4 by the DynaWave®. The residual SO2 content in the flue gas is typically less than 50 ppmv.
The SUPERCLAUS® process consists of a thermal stage followed by minimum three catalytic reaction stages with sulfur removed between stages by condensers. The first two or three reactors are filled with standard Claus catalyst while the final reactor is filled with selective oxidation catalyst. In the thermal stage, the acid gas is burned with a substoichiometric amount of controlled combustion air such that the tail gas leaving the last Claus reactor contains typically 0.8 to 1.0 vol.% of H2S. The SUPERCLAUS® catalyst in the final reactor oxidizes the H2S to sulfur at an efficiency of more than 85%.
Depending on feed gas conditions and unit layout, a sulfur recovery up to 99.2% can be achieved. The resulting SUPERCLAUS® tail gas is routed to an incinerator, in which all sulfur compounds are converted to SO2. In the downstream DynaWave® Reverse Jet Scrubber, scrubbing liquid is injected through a non-restrictive reverse jet nozzle, countercurrent to the incinerator flue gas. Liquid collides with down flowing gas to create a ‘froth zone’, a region with extreme turbulence, with a high rate of mass transfer. Quenching of the incinerator flue gas and SO2 removal from the gas occur in the froth zone, therewith creating sulfite salts. The clean, water saturated gas is then passed on to atmosphere through mist removal devices. The liquid reverses to the vessel sump for recycle back to the reverse jet nozzle. In the vessel sump, oxidation air is used to convert the sulfites to sulfates, that can be routed to waste water treatment.
- Application in both new and existing plants.
- Overall sulfur removal over 99.9%, also in case of bypassing the SUPERCLAUS® reactor stage.
- Capability to combust heavy hydrocarbon and aromatics.
- Long catalyst lifetime.
- Simple continuous operation.
- Low (additional) investment costs
- NH3 destruction.
- High turndown.
- High reliability - less than 1% unscheduled shutdown time.
- Small footprint, limited amount of equipment compared to amine based TGTU.
- In situ oxidation of the scrubbing effluent.