Molecular sieves are hard, granular substances manufactured from materials such as potassium aluminosilicates. They often have a spherical or cylindrical shape and their internal pores allow access to free volumes within their microcrystalline structure. As such, they are capable of trapping gases and liquids which have smaller molecular diameters. Others are thin membranes that perform a solution-diffusion separation process where components dissolve into the membrane surface and diffuse through it.
Application: Molecular sieves are commonly used for drying and removing CO2 from natural gas, LPG, inert or atmospheric gases.
Challenges: The high number of open/close cycles, the presence of corrosive sour gases and the extreme temperatures are among the many hurdles valves face within molecular sieve applications. Emerson has acquired over the years the know-how to manufacture an exceptionally reliable product that customers can trust for this critical application. For instance, Vanessa Series 30,000 valves have often been adopted by end users to replace rising stem tilting ball valves for CO2 membrane systems with open/close cycles as frequent as every 2-4 hours. They have also replaced High Performance butterfly valves which has proven extremely subject to wear. Thanks to their ability to operate without complications at temperatures of up to 600°F for a period of one to three hours, Vanessa Series 30,000 valves have been prescribed to handle such severe service conditions.