Molecular Sieves for Water Removal - Refinery Dryers| Pall Corporation

What Is a Molecular Sieve and How Does It Remove Water?

Molecular sieves, also known as adsorbents, are used for hydrocarbon drying to remove dissolved water from hydrocarbon gases and liquids. Refiners use molecular sieve dryers in a variety of dissolved water removal applications, including drying hydrocarbon gases for cryogenic separation, protecting water-sensitive catalysts and achieving final product water quality specifications.

Reliable molecular sieve dehydration is critical to maintaining process efficiency and supporting downstream refinery operations. High-efficiency filtration and separation technologies help protect molecular sieve systems from contamination while supporting dehydrator efficiency, capacity and desiccant bed campaign length.

When Is Molecular Sieve Water Removal Used?

Molecular sieve dryers are commonly used when refiners need to:

Remove dissolved water from hydrocarbon gases and liquids
Prevent ice and hydrate formation in cryogenic separation processes
Protect water-sensitive catalysts

Meet product water quality specifications
Support reliable refinery LPG production
Maintain desiccant bed performance and campaign length

Desiccant Protection from Free Water:

Desiccants must be protected from free water and liquid hydrocarbon contamination to maintain their effectiveness in gas drying applications. Free water causes long-term fracturing and dusting of the desiccant granules, while hydrocarbons burn onto the granules during the regeneration phase, progressively reducing moisture removal capability.

A premium solution is critical to achieving refinery LPG production reliability and scheduled campaign lengths through reliable treatment of wet gases.

High-efficiency SepraSol™ Plus Liquid/Gas Coalescers and Medallion™ HP Liquid/Gas Coalescers provide 99.999% liquid aerosol removal at 0.3 microns per the DOP test and 1 ppb downstream per the modified ANSI/CAGI-400-1999 test procedure.

Protecting Molecular Sieve Beds from Free Water Contamination

Learn how liquid/gas coalescers help remove water and hydrocarbon aerosols before molecular sieve drying.

For maximum protection against bed damage caused by liquid water ingestion, the SepraSol™ Plus liquid/gas coalescer assembly uses a dual-stage separation process combining knockout sump pretreatment with media coalescence.

The oleophobically and hydrophobically treated coalescers recover quickly from liquid slugs while minimising pressure drop across the assembly. By removing micron and sub-micron water and hydrocarbon droplets, the system helps maintain dehydrator efficiency and capacity while supporting desiccant life and minimising bed pressure drop increases.

Video explaining how liquid/gas coalescers remove water and hydrocarbon aerosols to protect molecular sieve dehydration systems

How Does Molecular Sieve Water Removal Work?

Molecular sieve systems rely on effective contamination control throughout the dehydration process.

Wet hydrocarbon gas or liquid enters the treatment system.
Coalescers remove liquid water and hydrocarbon aerosols.
Molecular sieve dryers remove dissolved water from the process stream.

Particulate filtration captures desiccant fines released during operation.
Dry product moves to downstream refinery processes.

Molecular Sieves for Dissolved Water Removal from Hydrocarbon liquids

When removing dissolved water from hydrocarbon liquids, liquid water is a damaging contaminant that can reduce desiccant life by causing long-term fracturing and dusting of the desiccant. The AquaSep® XS and AquaSep® EL liquid/liquid coalescers offer high-efficiency water removal to protect the desiccant, protecting the downstream catalyst beds, and ensuring the campaign life of the molecular sieve beds is achieved.

AquaSep® XS Coalescers

Pall's AquaSep® XS liquid/liquid coalescer system is a lower-cost solution for separating emulsions compared with cartridge coalescers, sand beds and electrostatic precipitators (ESPs). The system delivers cost-effective performance by enabling each coalescer element to process higher flow rates while maintaining superior effluent quality.

AquaSep® XS liquid/liquid coalescer for removing free water from hydrocarbon liquids

Learn how liquid/liquid coalescers protect molecular sieve systems by removing free water before dehydration.

Liquid/Liquid Coalescers - Liquid Separation and Particle Removal

Video demonstrating how liquid/liquid coalescers remove free water from hydrocarbon liquids before molecular sieve dehydration

Why Is Downstream Protection Important?

As molecular sieves age, they release desiccant fines that can damage downstream equipment and instrumentation. High-efficiency particulate filtration helps prevent these fines from passing downstream.

Gas Dehydration Applications
Liquid Dehydration Applications

A DGF Dry Gas Particulate Filter prevents damage to downstream process equipment due to entrainment of desiccant fines in the dry gas stream. A few styles are available for consideration.

MCC1401 Filter Cartridges use a pleated design with a steel core and are available with either Ultipor® or Epocel® media.

Ultipor® media provides high dirt-holding capacity, low clean pressure drop, long service life and low cost per gallon of gas processed.
Epocel® media uses resin-impregnated cellulose and is compatible with a variety of fluids.

Profile® Coreless Filter Elements eliminate the core to ensure a high-quality, high flow rate at a low cost. The Profile Coreless filter element fits over a 316L stainless steel core retained inside the filter housing.

At changeout, the element is simply removed from the core, which is then ready to accept the replacement element. Retaining the metallic core reduces the amount of waste, providing a lower cost, more environmentally friendly option.

Ultipleat High Flow filters effectively capture released molecular sieve fines. The Ultipleat® High Flow Filter System uses a large-diameter, coreless, single open-ended pleated cartridge with an inside-to-outside flow pattern.

Its crescent-shaped pleat geometry, combined with a 152.4 mm (6 inch) diameter and Pall filter media options, allows the use of fewer filters and smaller housings in high-flow applications.

Key Benefits

Up to 40 times fewer elements compared with 2.5" O.D. commodity filter elements
Flow rates up to 1900 lpm (500 gpm) per cartridge
Coreless all-plastic construction to minimise waste disposal

Absolute rated filter media for reproducible performance
In-to-out flow configuration that keeps debris contained within the filter
Easy element changeout and long filter service life

Pall filters help ensure gas dehydration results in both reliably meeting daily quotas and the need to protect downstream equipment. Not only do Pall filters save money, but their effective design and efficient filtering reduce waste and thus help protect the environment.

Pall SepraSol™ Plus Liquid/Gas Coalescers, MCC1401 Filter Cartridges, and Profile® Coreless Filter Elements maintain high quality at high capacity for a longer service life for natural gas dehydration. For more information on how this system works and can be installed, fill out the form on this page to talk to a Pall expert.

Which Pall Solutions Support Molecular Sieve Water Removal?

Applications	Pall Solutions
Protection from free water and hydrocarbon aerosols	SepraSol™ Plus Liquid/Gas Coalescers
High-efficiency liquid/liquid separation	AquaSep® XS Coalescers
Hydrocarbon liquid dehydration protection	AquaSep® EL Coalescers
Dry gas particulate removal	MCC1401 Filter Cartridges
Desiccant fines removal	Profile® Coreless Filter Elements
High-flow liquid filtration	Ultipleat® High Flow Filter System

Could Pall Molecular Sieve Protection Solutions Help Your Operation?

Discuss your application with a Pall specialist if you are looking to improve molecular sieve protection, extend desiccant life or support reliable dehydration performance.