Decarbonisation Technology August 2022 issue

Activated alumina


Heat of regeneration



Acid resistant



Lifetime Bed size

~3 yrs

5-10 yrs

Up to 4x larger bed sizes to match lifetime High Capex and Opex

Smallest bed sizes (high capacity material) Lowest Capex and Opex


Table 1 Comparison of activated alumina and Sorbead aluminosilicate properties

an aluminosilicate provides stability in CO₂ streams, it makes it susceptible to instability in the presence of basic contaminants, such as ammonia, amines, and olefins. However, if these impurities are present in low concentrations, they can be easily accounted for in the design of the CO₂ dehydration unit. If such contaminants are present in higher quantities, many upstream treatment methods are available. There are also many references of Sorbead units successfully operating downstream of acid gas removal units (AGRUs), where amine carryover could be a concern. Overall, the benefits of Sorbead stability in the presence of the primary, acidic CO₂ streams outweigh any instability in the presence of minor, basic impurities. Another significant benefit of Sorbead, particularly in CCS application, is its low heat of regeneration at 170°C. This lowers the overall energy duty of the dehydration unit and often allows for further cost reduction through the elimination of a regeneration heater. The

regeneration temperature for the aluminosilicate can often be attained through the utilisation of compressor waste heat or waste heat with the addition of a trim heater, further reducing the carbon footprint of the process. A standard Sorbead CO₂ dehydration unit utilising a trim heater to supplement compressor waste heat is shown in Figure 2 . BASF designs that employ counter-current heating and co- current cooling with wet gas and can easily reach CO₂ specifications of 30 ppmv H₂O. The design of these systems is also very flexible, allowing for both lower and higher specification ranges to be met with only small changes in design and cost (higher and lower, respectively). For example, even lower specifications of 10 ppmv H₂O can be reached by simply applying treated gas for regeneration. With this design, a regeneration compressor will be necessary. This demonstrates the reliability and flexibility of Sorbead for CO₂ dehydration. In an example study of a plant producing ~2.5

Heating Cooling

Trim heater (optional)

Balance valve

CO compressor

Dryer (regen)


Dryer (adsorption)

Regen gas separator

Inlet coalescer (optional)


Compressor aftercooler

Dry CO

Regen gas cooler

Dust lters

Sorbead dryer unit


Figure 2 Example CO₂ dehydration unit design that allows for CO₂ specifications as low as 30 ppmv H₂O


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