DEHYDRATION AND TREATING : PROCESS DRYERS

PROCESS DRYERS 2018-09-19T05:53:01+00:00

Gas Dryers and Treaters

GPE can design and execute gas dryers and treaters for almost all process gases using both temperature swing adsorption and pressure swing adsorption.

Chlorine Tatoray Off Gas Methylene Chloride
Hydrogen Ammonia Propane
Oxygen Carbon Dioxide Propylene
Nitrogen Carbon Monoxide Sulphur Dioxide
Argon Butadiene Helium
Acetylene Ethane Mixed Hydrocarbon
Butane Ethylene Natural Gas
Ethers Methane Mixed Gases
Oxy Purge Bio Gas Synthesis Gas

Common impurities that can be removed from a gas stream include water, carbon dioxide, carbon monoxide, mercaptan, ammonia, methyl alcohol, ethyl alcohol, hydrogen sulphide, oxygenates, acetylenes, nitrous oxide, nitrogen dioxide, propyne, and butyne. Some of these can be removed with the same adsorbent used for dehydration. For some, a separate adsorbent that can be regenerated is filled in the same bed. Some of the impurities cannot be removed by regenerable adsorbents. Here a separate bed with “sacrificial” adsorbent is used (Guard Bed) and operated up to complete equilibrium.

With a two bed system, the entire wet gas flows through the adsorption bed. Simultaneously, the bed in regeneration is being reactivated by flowing hot gases from various sources for a specific period of time. This is followed by a cooling phase. Depending on the flow rate, multiple beds are also used to keep adsorber size within manufacturing limits. The flow for adsorption is divided into two or more beds and one bed is regenerated. A single bed is taken into adsorption after regeneration and the time for adsorption per bed is determined by the regeneration time and the total number of installed beds.

In temperature swing adsorption the following standard regeneration possibilities can be offered.

  • Heat of compression- wet gas heating / dry gas cooling – closed loop
  • Split flow – wet gas heating / dry gas cooling – closed loop
  • Open loop external dry gas heating and cooling
  • Open loop nitrogen heating and cooling
  • Closed loop / semi-closed loop nitrogen heating and cooling
  • Closed loop dry gas heating and cooling
  • Single stream regeneration for multiple dehydration streams

Liquid Dryers & Treaters

GPE can design and execute liquid dryers and treaters for almost all process liquids using temperature swing adsorption.

Acetone Cyclohexane Propylene
Xylene Propane Heptane
Ethanol Butane Isobutane
Methanol Isopentane Pentane
Toluene Hexane Tetra Hydro Furan
Isopropanol Ethylene Ortho Dichlorobenzene
Benzene Naphthalene Ortho Chloro Aniline
Trichloroethylene Kerosene LPG

Common impurities that can be removed from a liquid include water, carbon dioxide, carbon monoxide, hydrogen sulphide, methyl alcohol, ethyl alcohol, olefins, di-olefins, chlorine, iodine, acetone, and carbonyls.

In liquid systems, the superficial velocity will be about 0.6 m/min because the mass transfer rate of molecules from the liquid (process) to solid (desiccant) is very slow. Moreover, while designing a liquid system, we provide higher contact times as the dynamic adsorption capacity of desiccants is much lower, typically 50% to 75% of that for gases. However liquid products can hold only about 15 to 20 % as much water as gases, so load imposed per unit of liquid is lower. The beds for liquid dryers and treaters require a more ‘square’ (larger diameter, smaller TL to TL length) design, are smaller in size and have increased cycle times as compared to gas dryer beds.

Standard regeneration possibilities offered are:

  • Open loop dry nitrogen heating and cooling
  • Closed loop dry nitrogen heating and cooling
  • Dry gas heating and cooling
  • Vaporised dry liquid heating and cooling
  • Vaporised dry liquid heating and dry liquid cooling