TopClaus® sulfur recovery – combining the best of two proven technologies
The TopClaus® sulfur recovery solution combines
- the industry-standard Claus gas desulfurizing process and
- the Topsoe wet gas sulfuric acid process (WSA)
to achieve 99.9+% sulfur removal efficiency (SRE) from acid gases – at significantly lower cost of ownership. You get the best of two thoroughly proven sulfur recovery technologies – combined for even greater benefits.
The Claus part of the TopClaus® solution is identical to the Claus technology that you know.
How it works
TopClaus® integrates the well-known, well-proven Claus and WSA processes. Acid gases are treated in the Claus unit of the TopClaus® plant, resulting in recovery of elemental sulfur. The tail gases from the Claus unit are treated in the WSA unit, where the remaining sulfur compounds are converted to sulfuric acid. The sulfuric acid is then returned directly to the Claus reaction furnace for reprocessing to elemental sulfur, with no sulfuric acid left as by-product. However, it is entirely up to the plant operator to draw off some of the sulfuric acid for specific uses or for sale, if desired.
Oxygen enrichment by sulfuric acid
Sulfuric acid (H2SO4) is a particularly efficient oxygen carrier, reducing the volume flow through the Claus unit just like with conventional oxygen enrichment, but without the high-temperature issues of the latter.
In the WSA unit all combustibles in the Claus tail gas like H2, CO, SX, CS2, COS and H2S are converted into H2O, CO2 and SO2, and the SO2 is further processed to sulfuric acid. Thereby final incineration of the tail gas becomes redundant, thus reducing fuel consumption and cutting back on your CO2 emissions.
Lower CAPEX and OPEX
Using a WSA unit as a TGTU in the TopClaus® process also brings you other benefits. When oxidizing the sulfur components to sulfuric acid, the WSA unit recovers as much as 90% of the heat generated, in the form of valuable superheated high-pressure steam that you can use in other key refinery processes, or use to generate electricity. This is in contrast to the large amount of steam that would be required to regenerate the amine in a conventional TGTU unit, and results in big reductions in your plant’s operating costs and CO2 footprint.
50% lower operating costs, combined with a reduction in capital expenditure of up to 40% compared to any conventional amine-based technology, provides you with a financially attractive, efficient and environmentally responsible solution for SRU design, be it a grassroot project or a revamp.
In addition, the TopClaus® configuration gives refineries operating a sour water stripper (SWS) greater flexibility and SRU reliability because the SWS gas can be by-passed around the Claus unit to the WSA unit, allowing a lower operation temperature in the Claus reaction furnace and preventing ammonia from causing problems in the Claus unit.
Eliminate bottlenecks and boost capacity
Oxygen enrichment by using sulfuric acid in the Claus reaction furnace provides you with excellent opportunities for boosting the sulfur recovery capacity and/or the SRE of an existing Claus plant.
The TopClaus® payoffs
Combining the capabilities and benefits of Claus and WSA technologies makes it possible to shift the benchmarks for reliability and costs.
- SRE >99.9%, with all sulfur compounds in the acid gas feed converted into elemental sulfur and/or commercial-grade sulfuric acid (if desired)
- Up to 40% CAPEX reductions
- Up to 50% lower OPEX
- More attractive net present value
TopClaus® sulfur recovery benefits
A TopClaus® installation can easily cope with virtually any acid gas feedstock (even those with a significant ammonia and hydrocarbon content) and any Claus tail gas composition you may have to deal with.
- Simple, robust and efficient plant
- Combines and integrates proven technologies – the efficient features of WSA with the industry-standard sulfur-producing Claus process
- Ideal for debottlenecking existing acid gas treatment plants, providing more uptime, increased capacity and/or lower emissions
- Equally suitable for greenfield projects and revamps
- H2SO4 is an efficient oxygen carrier, allowing higher throughput of the Claus unit
- You can export high-pressure steam – often superheated – that your plant can use elsewhere, instead of importing steam for amine regeneration
- Ammonia-related operational problems avoided because SWS gas treatment in the WSA unit makes sure ammonia is effectively burnt off
The TopClaus® technology has been developed by Haldor Topsoe and Comprimo, the leading licensor in gas treating and sulfur recovery technology.
The performance catalysts we supply for this application are listed below.
- CatalystsVK-WD is optimized for lean SO2+SO3 gases, such as in a SNOX™ plant or in the bed(s) after the intermediate condenser in a WSA-DC plant.
- CatalystsVK-WH is a cesium-promoted catalyst designed for continuous operation down to 370°C/700°F in medium- to high-strength SO2+SO3 gasses. A top-layer of VK-WH can significantly improve operating flexibility by widening the bed temperature control window, especially in plants struggling with fluctuating...
- CatalystsVK-WL is a cesium-promoted catalyst designed for continuous operation down to 370°C/700°F in lean SO2+SO3 gasses (less than approximately 2 mole%). At these conditions, VK-WL offers unmatched high activity throughout the entire operating temperature range. The very high activity provides the...
- CatalystsThe VK-WSA formulation offers excellent activity over a wide range of operating conditions and can be used in any bed of a WSA or WSA-DC converter. VK-WSA is available in the 12 mm Daisy shape and as a dust-protection catalyst in the large 25 mm Daisy shape. 12 mm Daisy: improved energy efficiency...
- CatalystsThe VK-WSX formulation was developed to offer higher activity in SO2 gasses that are more than 90% converted. Typically VK-WSX is used in the last bed of a WSA converter. For this service, VK-WSX is more active than VK-WSA and even more active than cesium-promoted VK-WH catalyst. The high activity...
The proprietary equipment we supply for this application are listed below.
- EquipmentThe ISAC is a small, packed column placed underneath the WSA condensers in WSA and SNOX™ plants. The purpose is to boost the acid concentration from what can be produced in the WSA condenser, e.g. 98%, to e.g. 98.5%. For special applications of sulfuric acid, a very high acid concentration is...
- EquipmentThe SOLVE filter is a special acid mist filter with an injection of hydrogen peroxide solution that oxidizes residual SO2 to SO3. The SO3 then immediately reacts with water vapor in the gas to form sulfuric acid that is captured in the low-velocity mist filter. SOLVE filters are supplied only in...
- EquipmentThe WSA condenser in WSA and SNOX™ plants cools the process gas with atmospheric air, typically from 280°C to 100°C. This first makes the SO3 in the process gas react with water vapor to form the sulfuric acid vapor, and secondly, the sulfuric acid vapor condenses to form the sulfuric acid liquid...
- EquipmentThe acid cooling system of WSA and SNOX™ The acid cooling system of WSA and SNOX™ plants performs a two-step cooling of the hot product sulfuric acid from the WSA condenser. First, the hot acid is quenched with cold acid, before going to a pump reservoir. Then the acid is pumped through the acid...