De-ethanizer Column Manufacturing: How Should This Product Work?

October 7, 2019

De-ethanizer columns shape the skylines of chemical processing plants. That's how large these towering metal structures can become, so a chosen manufacturing partner must be equipped to handle this kind of large-scale fabrication work. Functionally, the pressure vessels that fall under this fractionation category are designed to separate ethane from hydrocarbon-rich natural gas streams. In reality, there's more to the process than a simple separation mechanism.

Deconstructing a De-ethanizer Column

Immense pressures and high fluid boiling temperatures tear at the insides of these hollow pillars. Often several storeys tall, no square centimetre of the construct can present a single weld weakness or material flaw. That's an intimidating project specification, one that can't be properly understood until we take a peek inside the column to see how the inner workings of a de-ethanizer operate in real-time. Splitting the associated gasses into their component streams, the process begins after NGL (Natural Gas Liquid) is piped into the vessel. Perforated plates and trays are welded inside this unit, so it's obviously packed with a number of geometrically intricate features. As the fractionation operation commences, a heat exchanger delivers heat to the bottom of the vessel. The heat rises, carrying the evaporated ethane upwards, where it exits an outlet as a purified ethane condensate.

Fabricating Performance-Oriented Fractionation Vessels

There's normally at least two of these tall columns grouped together. They work in series as high-technology NGL processors. The de-ethanizer comes first. Stripped of ethane, the remaining hydrocarbons continue on to a de-propanizer, then on again to a de-butanizer.
That's how the equipment looks from the outside, like the giant wickets of a massive game of cricket. From the inside, things are a little more complicated. Split into its constituent parts, the manufacturing vendor has installed all the perforated plates and trays. They've been welded and exhaustively checked so that they'll contain the heat-evaporated ethane fraction. Otherwise, some small quantity of this hydrocarbon would continue on towards the other fractionation columns. Without fabrication quality management, without a quality control and inspection program monitoring those welded seams and vessel wall geometries, the purity of the fractionated fuels would be in question.

This is a three-way process, one that works in series to reduce natural gas liquids into their associated gasses and fuels. With de-ethanizer columns located at the front of this array of columns, the welded interior elements cannot exhibit any material discontinuities or dimensional inconsistencies. That's a quality control matter that guarantees pure ethane and pure butane or propane. If the heat exchanger vapours condense on the wrong levels or if those welded levels are found wanting, then purity issues will inevitably arise.

Contact Details

Fusion - Weld Engineering Pty Ltd
ABN 98 068 987619

1865 Frankston Flinders Road,
Hastings, VIC 3915

Ph: (03) 5909 8218

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