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Natural Gas Dehydration using Desiccant and Sizing (Bonus Free Spreadsheet)

In this post, I want to share you about natural gas dehydration using desiccant using adsorption principle and how to size it.

In common commercial use, desiccant can be classified into three categories, which are gels (alumina or silica gels), alumina, and molecular sieves.

When used for natural gas dehydration, silica gel will give outlet dewpoints of approximately -70o to -80oF. As for alumina, outlet dewpoint is appoximately -100oF. Molecular sieves produced the lowest water dewpoints, as low as -150oF. For gas going into cryogenic processing, the only adsorbent that can obtain the required dehydration is a molecular sieve.

Table below shows characteristics of several type of desiccants [1]. Read More

Several Natural Gas Dehydration Methods and Range of Application

In almost every gas processing plant, there will be natural gas dehydration unit. Sometimes, it is called dehydration unit (DHU) or dehydrator. When, I was working in Tripatra and involving in Senoro Gas Development Project, the facilities consisted of dehydration unit as one of them.

Natural gas dehydration unit is an important facilities in onshore and offshore gas processing plant. Its function are:

  • To mitigate risk of water condensation, which leads to flow capacity issues (pipeline clogging and blocking)
  • To prevent hydrate formation or to minimize corrosion
  • To ensure smooth operation in downstream facilities. For example, gas pipeline is usually required 4-7 lb/MMSCF water content (87.2-152.6 ppm). For cryogenic unit (to produce LNG), water content in gas shall be less than 1 ppm. For CNG plant, before entering compressor unit, water content shall be reduced to maximum 3 lb/MMSCF to meet product specification.

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