Moisture measurement in natural gas is very much essential. Natural gas is a gaseous fossil fuel found in oil fields underneath the earth. It mainly consists of methane along with Helium, some heavier gaseous hydrocarbons such as ethane, propane and butane, as well as other sulphur containing gases, in varying amounts. Natural gas is refined and processed to remove impurities like sand, hydrogen sulphide, water, heavier hydrocarbons and other gases before it is being transmitted via network pipelines.

The measurement of moisture content in natural gas is extremely important, from a technical perspective and in order to ensure conformance to contractual specifications. Typically, this measurement is one of the most difficult to perform successfully – natural gas sources are generally dirty, corrosive, heavily moisture laden and at high pressure. Moisture removal is a key stage of natural gas processing prior to sale and its efficiency is important in order to satisfy fiscal contractual obligations, to ensure that the gas is safe to transport and has the right properties for subsequent use. The key applications of moisture measurement are at: TEG Dehydration stations (Triethylene glycol is used to remove water from natural gas), Transmission pipelines, and Cryogenic gas plants.

Moisture in Natural Gas causes the following problems:

  • Freezing of control valves, regulators etc.
  • Accelerated pipeline corrosion
  • High moisture content also leads to formation of hydrates of liquid hydrocarbons present which will reduce the flow through the pipeline
  • Moisture reduces the BTU value of the gas
  • Specified moisture content for custody transfer (7lbs/MMSCF i.e. – 38 Deg. Td at 1 atmosphere)
  • Condensation at compressor stations

Advantages of having Moisture Monitoring for natural gas:

  • Less material & maintenance/labour cost for replacement of corroded pipe line, frozen valves, pressure regulators, compressor stations etc.
  • Hydrate formation is prevented and ensures a good flow
  • BTU content is maintained
  • Avoid penalties for failure to meet the custody transfer requirements