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Equipment

NGL Fractionation Systems

Natural gas liquids is the general term for liquids extracted from the natural gas stream — ethane and heavier products. To extract the individual components from the NGL, fractionation is typically required.

NGL fractionation columns
Project reference

LPG Production Facility at Umutu Delta State, Nigeria 2009

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ScopeDe-ethaniser, de-propaniser and de-butaniser within a 100 tonne a day LPG production facility.

Application

Recovering the Light Hydrocarbons

The recovery of light hydrocarbons refers to removing ethane, propane, butane and heavier hydrocarbons from the gas stream. Depending on the requirement, hydrocarbon dew point control units or cryogenic plants extract the NGL; fractionation then separates it into products.

Process

Fractionation

Fractionation separates the bulk natural gas liquid into component products — ethane, propane, butane and natural gasoline (C5+), or any combination of these. A series of fractionation towers exploits the relative volatility of the individual products to achieve the separation.

Heat is introduced at the bottom of the tower, driving the more volatile components to the top of the vessel. At the same time, liquid reflux entering from the top drives the less volatile components to the bottom. Trays installed within the tower keep the vapour and liquid phases continuously in contact, which is what allows the separation to occur.

Each tower takes the most volatile of the remaining components off overhead — not 100% pure, but within acceptable limits. The first product removed is therefore ethane, the lightest, followed by propane, butane and finally natural gasoline. The fractionation train is configured to achieve the required product cuts and specifications.

System configuration

Major Equipment Within the System

System configuration varies with process duty, operating conditions and project requirements.

  • Trayed process column with access platforms, illustration

    Fractionation Towers

    De-ethaniser, de-propaniser and de-butaniser: trayed towers in series, each taking the lightest remaining product off overhead.

  • Skid-mounted reboiler, illustration

    Reboilers

    Introduce heat at the bottom of each tower, driving the more volatile components to the top.

  • Air-cooled exchanger, illustration

    De-ethaniser Overhead Condenser

    Condenses the overhead vapour leaving the de-ethaniser.

  • Horizontal pressure vessel on saddles, illustration

    Reflux Accumulators

    Collect the condensed overhead, which the reflux pump returns to the top of the tower.

Also in the scope of supply

  • Rotating equipment: reflux pump

Final equipment arrangement and delivery format depend on process duty, transport constraints and site requirements.

Specifications

Products in Order of Removal

Removal orderProduct
1Ethane
2Propane
3Butane
4Natural gasoline (C5+)

Tower count, tray count and reboiler duty are designed by SPEC engineers so the final products match your specification.

Process data

What We Need for a Quotation

  • NGL feed composition
  • Feed rate
  • Feed pressure and temperature
  • Products required
  • Product specifications
  • Available heating and cooling utilities
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Welders working on a pressure vessel at SPEC's Jebel Ali fabrication facility

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Send us your process data and operating conditions, and we will review the duty with you.

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