Oil degumming separator: removing hydrated gums from crude vegetable oil to a residual-phosphorus target
The separator that takes the hydrated gums out of crude vegetable oil · residual phosphorus by degumming route, the gums-versus-oil trade-off in the bowl, two separators with gum recycle, and the feed temperature that decides how much will hydrate
In a seed-oil refinery, degumming means hydrating the phosphatides in crude oil with water or acid and then pulling the swollen gum phase out on a centrifugal separator. The separator decides two numbers at once: how much phosphorus stays in the oil, and how much oil leaves with the gums. In one refiner's patent tests, every setting that improved one worsened the other, and the feed — its temperature, the water dose, the contact time — fixes how much of the gum phase exists to separate in the first place. This page sets out the published targets, the measured trade-off and the feed conditions for this one duty.
Centrifugal separators used to remove the hydrated gum phase in water, acid and special (deep) degumming of crude vegetable oils and other triglyceride oils, with the hydration steps directly ahead of them. Disc stack separators as a machine class, equivalent settling area (sigma) sizing and cell-culture clarification are covered on the Disc stacks and disc stack separators page. Alkali neutralisation separators, soapstock splitting, bleaching and deodorising equipment, and enzymatic degumming chemistry are outside this page.
CNFX editorial research · Sources checked October 12, 2026 · 4 sources
Residual phosphorus each degumming route asks the separator to reach
Alfa Laval's review of degumming technologies gives target results after the separator for each route. The phosphorus figure is what a refinery buys the separator to deliver; the AI (acetone-insoluble) content of the dried gums shows how much of the gum phase is phosphatide rather than entrained oil. [1]
The same review lists what the next refining step will accept: physical refining of seed oils needs phosphorus below 5 ppm (below 2 desired), chemical refining accepts below 1200 ppm with below 200 desired. [1] It also lists the starting load: crude soya 400–1200 ppm phosphorus, rapeseed 200–1400 ppm, sunflower 200–500 ppm, cottonseed 400–1000 ppm, corn 250–800 ppm and palm 15–30 ppm. [1]
Editorial calculation: for a soybean crude at 800 ppm phosphorus (inside the 400–1200 ppm range above), a water-degummed oil at 200 ppm means 75% of the phosphorus has left with the gums; a special-degummed oil at 30 ppm means about 96%. A palm oil at 15–30 ppm already sits at the special-degumming target before any separator, so the duty and the case for a gum separator differ by oil.
Route (Alfa Laval)
Conditions before the separator
Phosphorus in oil
AI in dried gums
Moisture in dried oil
Water degumming
Heat to 60–70 °C, add water, hydration mixing 30 minutes [1]
Fewer gums in the oil or less oil in the gums: what centripetal pump, outlet pressure and top disc did on one separator
Vandemoortele's patent EP 0349718 measured this trade-off on acid-conditioned, water-degummed soybean oil of about 200 ppm phosphorus, with each first-stage separator followed by two water-washing centrifuges. Every change that removed more gums put more oil into the gum phase, and every change that dried the gums left more gums in the oil — which then showed up as refining loss in the wash water and residual phosphorus. [2]
All rows from the patent's Example 1 summary table. [2] The patent's conclusion is that the equipment tested could not deliver low oil in the gums and low residual gums in the oil at the same time. [2]
Editorial calculation: on a line processing 13,500 kg/h of oil (the plant rate in the Lisbon study below), the difference between 0.27% and 0.04% refining loss is about 31 kg/h of oil, or roughly 745 kg a day of continuous running. [2][3]
First separator and setting
Gum removal
Oil in gums (dry basis)
Refining loss in washing
P after two washes
Self-cleaning disc centrifuge, standard centripetal pump
88%
20%
0.20%
11.1 ppm
Same, optimised centripetal pump, normal outlet pressure
93%
22%
0.18%
8.0 ppm
Same, optimised pump, low oil outlet pressure
88%
16%
0.27%
12.3 ppm
Same, optimised pump, high oil outlet pressure
96%
65%
0.04%
6.0 ppm
Decanter, long nozzles (77 mm)
96%
70%
0.17%
5.1 ppm
Decanter, short nozzles (70 mm)
85%
32%
0.35%
14.2 ppm
Solid-bowl disc centrifuge, standard top disc
94%
85%
0.15%
8.1 ppm
Same, modified top disc
87%
40%
0.23%
12.6 ppm
When comparing quotations, ask each supplier to state gum removal (or residual phosphorus) and oil content of the gums at the same throughput and feed, since the patent data show a separator can be set to look good on either one alone.
03
Two separators in series with the oily gums recycled to the first
The patent's answer is to stop asking one machine for both results: set the first separator for low-oil gums, set a second one for low-gum oil, and send the second separator's oily gum stream back into the feed of the first. [2]
In Example 2, a solid-bowl disc centrifuge alone removed 85% of the gums at 38% oil in the gums, and washing the oil cost an extra 0.21% refining loss. Adding a self-cleaning disc centrifuge with nozzles for continuous gum discharge, recycling its gums to the crude oil supply tank, brought the refining loss to 0.05% and the washed oil to 4.6 ppm phosphorus. [2] The recycled gums carry above 90% oil on a dry basis, the recycle amounts to 5 to 20% of the gums originally present, and the patent reports it reached a steady state with no accumulation. [2] In that example the second separator's nozzles occasionally blocked and were cleared by feeding water to it. [2]
In Example 3, a single self-cleaning separator gave 94% gum removal, 26% oil in the gums, 0.16% washing loss and 7.0 ppm phosphorus; feeding its oil to a second self-cleaning separator discharging every 1 to 4 minutes brought washing loss to 0.09% and phosphorus to 5.4 ppm, before nozzles and recycle replaced the discharges. With recycle, net throughput fell to about 85%. [2]
04
Feed temperature and water dose: how much of the gum phase exists before the separator
A study of the water-degumming step at Iberol's Alhandra plant (Instituto Superior Técnico, Lisbon) found the oil entering hydration at 98 °C instead of about 75 °C. The authors note that higher temperature raises phosphatide solubility in oil, and measured degumming efficiencies between 57.0 and 82.4% against roughly 90% hydratable phosphatides in soybean oil. [3]
The authors concluded that cooling the oil to 75 °C raises degumming efficiency by 8.6% and modelled an efficiency of 89.6% against 81.0% currently, with degummed-oil loss rising from 1.63% to 1.84% but neutralisation oil loss falling from 0.90% to 0.57%. [3] They preferred shell and tube coolers to a rebuilt plate exchanger because crude oil's dissolved solids can damage plates and rebuilt plates may leak. [3]
Vandemoortele's patent describes the conventional water-degumming feed as about 3% water or steam added to crude soybean oil at around 70 °C, with the hydrated phase removed on disc centrifuges. [2] Editorial calculation: the Lisbon plant's 350–550 kg/h of water on 13,500 kg/h of oil is 2.6–4.1% of the oil flow. [3]
Efficiency 79.5–82.2%; total loss 4.03–4.49%; oil loss 1.63–2.01% [3]
05
Bottom feed, interface control and discharge volume on a current degumming separator
Alfa Laval's case story on the XSEED 80 at a Brazilian soybean processor (Camera Agroindustrial) states what it changed against the separator it replaced: 20% more processing capacity, oil losses reduced by 0.5%, residual phospholipid in the degummed oil below 10 ppm, and on average 25% less water. [4] These are supplier-reported results from one site.
Interface position and discharge volume are the same levers the Vandemoortele data show moving gum removal against oil in the gums, so a buyer can ask any supplier how each is set and held during the discharge cycle. [2][4]
Feature named in the case story
What Alfa Laval says it does
Hermetic inlet
Product enters through a hollow spindle at the bottom of the bowl and flows directly into the disc stack; less pulverisation of the heavy phase [4]
Moves the interface before discharge so the heavy phase is pushed toward the centre, avoiding loss of the liquid seal and reducing oil losses [4]
Operating Water Module
Pneumatic piston with compressed-air buffer; discharge volume adjusted proportionally [4]
Variable speed
Every 10% reduction in bowl speed saves up to 20% of energy consumption [4]
Bowl materials
High-performance stainless steel bowl for corrosion resistance in some degumming methods; hard chromium plating of bowl and discharge liners for wear [4]
06
Data for a degumming separator enquiry
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Oil: [type; crude phosphorus ppm; FFA %; throughput t/day]
Route: [water, acid or special degumming; acid type and dose; holding time]
Feed: [hydration temperature; water dose % of oil]
Targets: [phosphorus ppm in oil; oil content of gums, dry basis; moisture after drying]
Downstream: [physical or chemical refining; washing stage]
Separator: [one or two in series; gum discharge by centripetal pump, nozzles or intermittent discharge; bowl material]
Gums: [lecithin, meal or other outlet]
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What residual phosphorus should a degumming separator reach?
Alfa Laval targets 50–200 ppm max. after water degumming, 20–50 ppm after acid degumming and 20–30 ppm after its special degumming, 8–10 ppm with a water wash. [1]
Why does more gum removal raise oil losses in the gums?
In Vandemoortele's tests, raising oil outlet pressure lifted gum removal to 96% but raised oil in the gums to 65% (dry basis); lowering it gave 16% oil but only 88% removal. [2]
Does feed temperature matter for water degumming?
In the Lisbon study, soybean crude hydrated at 75 °C gave 108 ppm P against 153 ppm at 98 °C. [3]
Why use two separators in series?
Vandemoortele sets the first for low-oil gums and the second for low-gum oil, recycling the second's gums; refining loss fell from 0.21% to 0.05% and phosphorus to 4.6 ppm. [2]
Sources and what still needs a direct check
Sources checked 2026-10-12. Degumming routes and targets come from an Alfa Laval review presented at an SCI oils and fats meeting; separator trade-off and two-stage data from Vandemoortele's European patent application; feed temperature and plant data from an Instituto Superior Técnico study at Iberol; current separator features from an Alfa Laval case story.
