An edible oil refinery is a steam plant with a hygiene finish
An edible oil refinery takes crude oil and removes the things that make it dark, smelly or unstable. Degumming uses water and acid, neutralisation uses caustic, bleaching uses clay, and deodorising uses high temperature under vacuum.
Each of those steps brings something to the building: heat, vacuum, aggressive chemistry, or a fine powder that goes everywhere.
The deodoriser is tall and hot
Deodorisation runs at high temperature under deep vacuum in a tall column with a packed section. The column needs headroom, the vacuum system needs a place to stand, and the whole assembly radiates heat into the room.
As with any tall vessel, the eave height comes from the elevation and the pipework above it, and the removal route has to be considered while the roof is still open.
Caustic and acid reach the floor, not the roof
Neutralisation produces a soapstock stream and uses caustic. Degumming uses phosphoric or citric acid. Both find their way to the floor through drips, sampling points and washdown.
The roof of an oil refinery is usually the least affected part of the envelope. The floor, the column bases and the first metre of wall are where the building ages. Specifying a heavy coating on the roof while leaving the base detail as a bare steel plate is a common misallocation.
Bleaching clay is a dust that never fully leaves
Bleaching earth arrives as a fine powder, is dosed into the oil, and is filtered out afterwards. The dosing and filter areas are dusty, and the dust is abrasive as well as being a nuisance.
It settles on purlins, on equipment tops and in every roof profile. Combined with any moisture at all it forms a layer that holds water against steel. Smooth, cleanable surfaces in the filter area are worth more than a heavier frame.
The plant is a tank farm with a building attached
Crude storage, intermediate storage and finished storage usually account for more volume than the process itself. Those tanks are outside, and the building is threaded between them.
That arrangement makes the bunds, the pipe bridges and the fire separation of the tank farm the dominant site decisions. The process building then has to fit between fixed tank positions, which constrains its grid before any process equipment is placed.
What I want before drawings
- The process flow with the vessels, their heights and their support arrangements.
- The chemicals used, their concentrations and how they are handled.
- Where the tank farm is, and what separation is required between it and the building.
- The washdown regime and the floor drainage concept.
- Whether the vacuum system and heating are inside the building.
- The wind speed for the site in km/h from the applicable local code, not a round number.
Refineries are usually expansions of an existing crush plant, which means the building has to fit a site that was laid out for something else. Finding that constraint at the start is much cheaper than meeting it during erection.
Written by Johnny Joe, who advises owners and project managers in Africa and South America on steel buildings. If this decision is live on a project, send the layout and the constraint that worries you and I will tell you what it changes.
Related: the press hall upstream · vessel loads and cleaning in place · corrosion class as a selection input · heat and caustic in one room
