Gas Treatment & Drying

Natural Gas Dehydration

Removing water vapour from natural gas to prevent hydrates and corrosion and to meet pipeline dew-point specification, using molecular-sieve TSA adsorption.

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Quick Answer

Natural gas dehydration by adsorption removes water vapour by passing the gas through a packed bed of molecular sieve. Twin-tower temperature-swing adsorption (TSA) systems achieve outlet water dew points below −40 °C at pipeline pressure, meeting GPA 2140 and pipeline operator specifications.

Process Challenge

Produced gas is water-saturated at reservoir conditions. Liquid water and hydrates cause corrosion, pipeline blockage, and measurement error, and prevent the gas from meeting a sales-gas water dew-point specification of typically −10 °C to −40 °C at MAOP.

How Adsorption Dehydration Works

A bed of molecular sieve captures water by physisorption as wet gas passes through. When the bed approaches saturation it is regenerated by heating to 250–300 °C with a dry purge, then cooled before returning to adsorption. Twin or triple vessels give continuous duty.

Desiccant Selection

Molecular Sieve 3A is the standard choice for sales gas, minimising hydrocarbon co-adsorption; 4A is reserved for pure-methane maximum-capacity duty. Guard layers protect the main bed from bulk water.

FAQ

What dew point is achievable?

Below −40 °C, and below −70 °C in deep-bed designs — meeting pipeline and cryogenic-feed specifications.

How long is a typical cycle?

8–24 hours per adsorption half-cycle, depending on inlet water load, bed volume, and target dew point.

Selection Guidance

For sales gas containing C₂+ hydrocarbons, use Molecular Sieve 3A to avoid co-adsorption losses. For pure methane where maximum capacity matters, 4A may be used. Add an activated-alumina or silica-gel guard layer for high inlet water or liquid-carryover risk.