Compressed Air & Gas Dryers

CO₂ Dryer

Beverage-grade dry CO₂ from your recovery plant, with the gas used for drying returned to your process, not vented.

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A twin-tower CO₂ adsorption dryer in stainless steel on a skid, with its valves, pipework and control panels

Product overview

Dry CO₂ your liquefier and your customers can rely on

Our CO₂ dryer takes the water-saturated gas in your recovery plant, typically at 15–20 bar g, and adsorbs its water on a solid desiccant until only a few ppm v/v remain. That keeps your liquefier free of ice and your product within its moisture specification.

Two towers of 3A molecular sieve share the work: one dries while the other is regenerated with heated dry CO₂, and they change roles on a cycle of several hours, so drying never stops. The regeneration gas is cooled, its water drained, and returned to your compressor suction, so the CO₂ used for regeneration is recovered rather than vented.

At 18 bar g and 25 °C, saturated CO₂ carries about 1,670 ppm v/v of water. Reaching the ISBT beverage-grade limit of 20 ppm v/v means removing about 98.8 % of it, a frost point of about −30 °C at line pressure.

A twin-tower CO₂ adsorption dryer in stainless steel on a skid, with its valves, pipework and control panels
  • 20 ppm v/vISBT beverage-grade water limit
  • 98.8 %Of the water removed, from saturation at 18 bar g and 25 °C
  • About −30 °CFrost point at line pressure
  • ZeroCO₂ lost in regeneration

Benefits

The problems it solves

Every recovery route leaves your CO₂ saturated with water. Here is what that water does, and how the dryer stops it.

  • Ice in the liquefier

    The problem

    Water reaching the condenser at liquefaction temperatures freezes as ice and CO₂ hydrate, cutting capacity until the plant stops to defrost.

    How it solves it

    Gas with a −30 °C frost point at line pressure cannot deposit ice at the −21 °C condensing temperature, so your refrigeration plant runs without defrost stops.

  • Failing the beverage specification

    The problem

    Beverage producers audit their CO₂ against the ISBT limit of 20 ppm v/v water, and gas that cannot show a compliant level cannot be supplied for carbonation.

    How it solves it

    Molecular sieve beds routinely deliver well below 20 ppm v/v, and continuous outlet moisture measurement gives you the records your quality audits ask for.

  • Product lost to regeneration

    The problem

    The CO₂ is your product, and every kilogram vented during regeneration must be recovered again or bought in.

    How it solves it

    The regeneration gas returns to your compressor suction. The only material leaving the loop is liquid water.

  • Carbonic acid corrosion

    The problem

    At 19 bar CO₂ partial pressure, condensate reaches about pH 3.3 and attacks carbon steel pipework, storage tanks and valve bodies.

    How it solves it

    Without liquid water, CO₂ cannot form carbonic acid, so your downstream equipment is protected and no dissolved iron reaches the product.

  • Ice in storage and distribution

    The problem

    Water entering the storage tank freezes as ice crystals that block level gauges, safety valves, pump suctions and vaporiser inlets.

    How it solves it

    Dry gas keeps your liquid CO₂ storage and distribution free of ice.

  • Product held in the bed

    The problem

    Many zeolites adsorb CO₂ strongly, loading the bed with product gas and competing with water for sites.

    How it solves it

    3A sieve pores, about 3 Å across, admit water at 2.65 Å and largely exclude CO₂ at 3.3 Å, so little product is held and the gas leaves unchanged apart from its water.

Where it’s used

Wherever CO₂ is recovered, dried and liquefied

From fermentation tanks to synthesis gas, recovered CO₂ has to be dry before it can be liquefied, stored and sold.

  • Wine bottles moving along a bottling line

    Breweries and soft drinks

    Fermentation CO₂ recovered for carbonation, bottle and keg purging and tank counter-pressure, and certified to beverage grade for bottlers.

  • Test tubes of coloured chemicals in a laboratory rack

    Ammonia and hydrogen plants

    CO₂ removed from synthesis gas, purified and dried for urea production, merchant liquid CO₂ and dry ice.

  • Yellow tablets spilling from a medicine bottle

    Pharmaceuticals and extraction

    CO₂ within the European Pharmacopoeia water limit of 67 ppm v/v, and recirculating CO₂ for supercritical extraction of hops, coffee and botanical oils.

Also wineries and distilleries, bioethanol plants, natural gas processing and biogas upgrading, carbon capture, utilisation and storage, industrial gas producers, food processing and dry ice, greenhouse CO₂ enrichment and water treatment.

How it works

Adsorb, heat, recover, cool

Two towers take turns. While one dries your CO₂, the other is heated to drive off its water, then cooled and made ready for its next turn.

How a CO₂ dryer works: wet CO₂ flows down through Tower A, where molecular sieve adsorbs its water, and dry CO₂ leaves through an after-filter to the liquefier. Meanwhile a side stream of dry CO₂ is heated and flows up through Tower B to drive off its water, then passes through a cooler and separator, where the water drains, and returns to the compressor suction. The towers change roles on a cycle of several hours. Wet CO₂ inSaturated · 18 bar g Tower Adrying Tower Bregenerating 200–300 °C After-filterDry CO₂ outbelow 20 ppm v/v HeaterFlow control Regeneration cooler SeparatorBack to compressorsuctionCondensate out 12345Wet CO₂Dry CO₂Hot regeneration CO₂CondensateWater held in the sieveValve closed

  1. 1. AdsorbWet CO₂ flows down through Tower A. The 3A molecular sieve holds its water, and dry CO₂ leaves at the bottom, through the after-filter, to your liquefier.

  2. 2. HeatA side stream of dry CO₂ is heated and flows up through Tower B, against the drying direction, taking the sieve to typically 200–300 °C. A temperature front climbs through the bed and drives the water off.

  3. 3. RecoverThe hot, wet regeneration gas passes through a cooler, where most of its water condenses, and a separator drains it away. The CO₂ returns to your compressor suction, so none is vented.

  4. 4. CoolThe heater switches off, and unheated dry CO₂ carries the stored heat out of Tower B until it is close to process temperature. The tower returns to line pressure and waits, fully regenerated.

  5. 5. Change overWhen Tower A reaches the end of its adsorption phase, typically after several hours, the valves switch and the towers change roles, so drying carries on without interruption.

Typical figures for saturated CO₂ at 18 bar g and 25 °C.

Get the full details

Our brochure covers it in detail, and our questionnaire tells us what we need to recommend the right one for your plant.

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