Gas Dryers, Filters, and Purifiers Information

Nitrogen membrane filterGas dryers remove liquid droplets, such as entrained water, within a gas stream; gas filters remove particles from a gas stream; and gas purifiers remove gaseous contaminants from a gas stream to levels as low as one part per trillion (ppt). They are important components to any gaseous process stream. 

Gas dryers, filters, and purifiers are commonly used in gas extraction and natural gas processing systems, gas streams that require the removal of moisture and oxygen to prevent corrosion, and to eliminate point-of-use impurities in gases such as helium, hydrogen, methane, nitrogen, or carbon dioxide. They are often used with hydrogen-cooled electrical power generators.

Types 

Gas dryers, filters, and purifier housings are commonly made of aluminum, plastic, steel, sNautral and synthetic fiber process filtertainless steel, and Teflon®. The filter medium can be made of a variety of materials and sometimes multiple materials. These materials include activated carbon, activated clay, diatomaceous earth (DE), cellulose, ceramic, cotton, glass fiber, ion exchange resin, metal, minerals and sand, nylon, paper, polyethersulfone (PES), polyester, polypropylene (PP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polysulfone (PSU), and synthetic fiber. 

Configurations 

There are two basic configurations for gas dryers, filters, and purifiers.

  • In-line filters are assemblies in which the inlet, outlet, and filter element axes are in a straight line.
  • Return line or closed loop filters catch all debris generated by the system’s components. They are designed to be the last component passed before returning to the system reservoir.

Specifications 

The follow specifications determine the functionality of gas dryers, filters, and purifiers. 

  • Filtration grade: filtration grade (micron rating, Beta ratio) describes the ability of a fluid filter to remove contaminants by particle size.
  • Maximum temperature: maximum media temperature the unit is designed to receive.
  • Maximum pressure: maximum pressure the unit is designed to operate at.

Features

These features provide additional utility or ease-of-use. 

  • FDA compliant: The filter meets requirements from the U.S. Food and Drug Administration (FDA) that allows it to be used for food and beverage or pharmaceutical applications.
  • Pressure drop or differential pressure indicator: If there is abnormally high differential pressure across the unit it may indicate a failure or clogged filter. An indicator allows for immediate action that can prevent damage to the unit and associated systems.
  • Reusable/cleanable elements: The elements used with the unit can be cleaned or refurbished to allow reuse in lieu of replacement.
  • Portable cart mounting: The unit is mounted on a cart designed to hold the weight of the unit, allowing portability and mobility.

Image credit:

Air Products | Shelco Filters