Bunch steriliser
Steam treatment of bunches: the operation that sets the acidity of the entire production.
What this machine does
The steriliser decides oil quality long before the press. The mesocarp of the palm fruit contains an endogenous lipase which, as soon as the fruit is bruised or detached, hydrolyses the triglycerides and releases free fatty acids: oil acidity rises hour by hour. Saturated steam at high temperature denatures that enzyme and halts the process. A bunch treated on the day it is cut gives markedly less acidic oil than the same bunch treated two days later.
Sterilisation performs three other functions at the same time: it eases the detachment of fruit from the stalk, softens the mesocarp and prepares the rupture of the oil-bearing cells, and conditions the nuts for the kernel line. Its conduct rests on a technical point that is often neglected: the successive air purges. A pocket of air trapped in the vessel is a cold zone where the real temperature stays below the set point — and where the lipase survives, whatever the pressure gauge shows.
See the sector Oil palmAt a glance
- ReferencePAL-STE
- SectorOil palm
- PurposeSteam treatment of bunches: the operation that sets the acidity of the entire production.
A detailed PDF data sheet will be available in the document centre once produced.
The parts that do the work
Pressure vessel
Horizontal or vertical body receiving bunches in baskets or cages.
Purge cycle
Sequence of admissions and purges removing residual air, the condition of uniform temperature.
Pressure-time control
Holding of the sterilisation plateau with monitoring and, where possible, recording of the cycle.
Safety devices
Set safety valves, door interlock and devices preventing opening under pressure.
Technical data and configurations
| Characteristic | Indicative value |
|---|---|
| Batch capacity | 0.5 to 5 t of bunches depending on model |
| Working pressure | 2.5 to 3 bar (saturated steam) |
| Plateau duration | 60 to 90 min depending on load |
| Purges | successive air-removal cycles |
| Steam supply | dedicated boiler sized on the cycle |
| Loading | baskets or cages |
| Safety | relief valve, door interlock, inspected gauge |
| Regulations | pressure equipment subject to periodic inspection |
These are usual design ranges for this type of machine, intended to guide early thinking. The contractual characteristics of the equipment actually manufactured — throughputs measured at acceptance, absorbed power, real footprint and weight — are established by the SOTIC design office and stated in the technical offer.
Available configurations
- Horizontal cage configuration or vertical basket configuration according to site layout.
- Capacity matched to the daily tonnage of bunches received.
- Recording of the pressure-time cycle for traceability.
Installation requirements
- Concrete block sized for the mass of the loaded vessel.
- Lagged steam network with traps, from a boiler sized on the cycle and not on the hourly average.
- Clear manoeuvring area in front of the door, with marked cage circulation.
- Organised drainage of condensate and purge effluent.
Maintenance and safety at the workstation
A machine lasts as long as its maintenance does. The points below appear in the preventive maintenance plan handed over at acceptance and are covered during operator training.
Preventive maintenance
- Statutory periodic inspection of the pressure vessel, non-negotiable.
- Check door gaskets and the interlock system every campaign.
- Check the steam traps: a blocked trap distorts the whole cycle with no visible sign.
- Calibrate the pressure gauge and the temperature probes.
Safety
- Opening is strictly forbidden until the pressure is zero: the interlock must never be defeated.
- Steam burn risk at purging: the area must be marked out.
- Mandatory training of the operator in pressure equipment operation.
Before ordering this machine
This is the most widespread false economy in palm oil milling. Shortening the plateau leaves part of the load insufficiently treated: the lipase survives in the coolest zones, oil acidity rises and fruit detachment stays incomplete, which also lowers yield. To increase capacity you add sterilisation capacity; you do not shorten the cycle.
It is sized on the steam demand of the sterilisation cycle, which is a short, heavy call, and not on the mill's average consumption. Press fibre and kernel shells are fuels available on site and cover a significant share of the demand, provided the boiler is designed for them and storage is under cover.
Request a quote: Bunch steriliser
Tell us the throughput you are aiming for, the material to be processed and the energy available on your site: we come back with a reasoned configuration and a price, rather than a catalogue rate.
- Technical answer: we first check that this machine genuinely matches your need.
- Tailored configuration: size, drive, options and wear parts defined with you.
- Complete pricing: equipment, transport, erection, commissioning and training.
- Next steps: civil works, connections and maintenance where required.
First reply target: 48 working hours.
Other machines in the Oil palm
Bunch stripper
Separates fruit from empty bunches after sterilisation, in a rotating barred drum.
Palm fruit digester
Heated mixing that breaks down the mesocarp and ruptures the oil-bearing cells.
Palm oil press
Mechanical extraction by reducing-pitch screw, with counter-pressure adjustable while running.
Oil filter
Clarifies crude oil by filtration, before storage or refining.