Crude Palm Oil Mill Process
Palm oil (also known as dendê oil, from Portuguese) is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of the oil palms, primarily the African oil palm Elaeis guineensis, and to a lesser extent from the American oil palm Elaeis oleifera and the maripa palm Attalea maripa.
Palm oil is naturally reddish in color because of a high beta-carotene content. It is not to be confused with palm kernel oil derived from the kernel of the same fruit, or coconut oil derived from the kernel of the coconut palm (Cocos Nucifera).
The differences are in color (raw palm kernel oil lacks carotenoids and is not red), and in saturated fat content : palm mesocarp oil is 41% saturated, while palm kernel oil and coconut oil are 81% and 86% saturated fats, respectively.
Palm oil mill process is quite diffferent from other oil seeds processing, such as the soybean , peanut etc. Palm fruits consists a lot of fatty acid enzyme, which would hydrolyze palm oil. That's the reason why palm fruit must be sent into processing in 24 hours.
At the mill, the main products that are produced from FFB are Crude Palm Oil (CPO) and Palm Kernels.
Mill Process
By products are generated at the palm oil extraction mill, in which crude palm oil (CPO) and kernels are produced from the Fresh Fruit Bunches (FFB). At the extraction mill, the upstream production process consists of a number of process steps for production of CPO and kernel (Corley et al., 2003 ) :
Bunch sterilization with the aid of steam: this loosens the oil-containing fruit from the bunch and inactivates lipid-degrading enzymes as well as micro-organisms that naturally occur in FFB.
Bunch stripping, which separates the fruit from the bunch stalk and spikelets. In this process, the byproduct Empty Fruit Bunch (EFB) is produced.
Fruit digestion to crush and disrupt the mesocarp (pulp), with the aid of steam.
Pressing of the digested fruit to extract the oil from the mesocarp fibre. In this process, two fractions are produced: raw oil and a residue, containing palm oil fibres and nuts.
Separating, clarifying and drying the CPO.
Separating the nuts from the oil palm fibres. In this process step, the byproduct Oil Palm Mesocarp Fibres are produced, or fibres for short.
Drying, grading, and cracking of the nuts, producing Palm Oil Kernels and shells.
Separating Kernels from the shells. In this process step, the by-product Oil Palm Kernel Shells, or Shells for short, is produced.
Kernel drying and storage
A palm oil mill produces crude palm oil and kernels as primary products and biomass as secondary product. A typical mill has many operational units as shown in Figure 2. This comprises of sterilization, stripping, digestion and pressing, clarification, purification, drying and storage. For the kernel line, there are steps such as nut/fiber separation, nut conditioning and cracking, cracked mixture separation, and kernel drying and storage. The dried kernels are often sold to palm kernel crushers for extraction of crude palm kernel oil. In some integrated plants, kernel crushing facilities exist side by side in the same complex.
Collecting the ripe fresh cluster from the orchard and convey by trucks, then pour the fluster into the discharge door after weighed by ground weigher . The discharge door has discharging channels, the upper and lower switches of the iron gate are controlled by pneumatic, Pneumatic control system consists of air compressor and pneumatic control devices. Start the control valve to open the gate of the discharge door, then the palm fruits will fall into the fruit basket car or conveyor.
Sterilization deactivates the lipases in the fruits, and prevents build-up of free fatty acids (FFA). Vertical sterilizers are also available, which are much cleaner and easier to operate than conventional sterilizers. Fresh palm fruit bunch are airtight sterilized in sterilizer, injecting direct steam (the pressure is 300KPa) to heat 60mins. The purpose is to prevent enzymes broken down, avoiding FFA content in oil further increase.
Two cage tippers are used with the individual Sterilized Bunch Conveyor that feeds two main Threshers. Empty bunches will be recycled by the conveyor to bunch Crushers before being fed to a third thresher for recovery of unstripped fruitlets. With this system, oil and kernel extraction will be enhanced. The purpose of threshing is to separate the palm fruit from the FFB. The drum type thresher is the usual machine to separate the fruit. The separated oil palm fruit is sent into the pressing section. Empty fruit bunch be ejected to the yard from the other side of the revolving drum, or shipped out from the plant as palm orchards slipcover to recycling use, or burning in the locale as fertilizer for agricultural land.
Fruitlets are passed to a pressing Station for recovery of oil from the mesocarp. There is also the steam heater in masher. The purpose of mashing is to separate the pulp and nut and crush the palm pulp. At the same time, the steam is used to cook the palm fruit and broke the cell of pulp. Because of cooking, sterilizing, threshing and mashing made the pulp soft and damage pulp cell structure, the palm pulp becomes soft and cell is broken. Then it is sent to continuous screw press. After pressing, oil palm fruit is divided into two parts: the mixture of oil, water and solid impurities, and the press cake (fiber and nut). Crude oil is collected in a Crude Oil Tank and pumped to the Clarification Station. The digested mesh is conveyed to the Depricarping Station for the recovery of nuts and fiber used as boiler fuel.
The oil clarification process uses a Static Vertical Clarifier and three phase Decanters, Oil purifiers and an Oil Vacuum Dryer. The use of the Vertical Clarifier will ensure efficient sludge and oil separation whereas the decanter will ensure solid removal for efficient effluent treatment. Machine-pressed crude oil first diluted with water washing, through settlement and filtration, the fiber material removed from the oil, and then carry out continuous settlement, the whole divided into two parts: oil and sediment. Oil by centrifugal separation and through vacuum drying pumped into the storage tank for storing; oil sediment by filtration and dirt oil separation, oil process second settlement, dirt oil mixture process clarification separation, Skim oil then carry out a second settlement, sewage pumps to sewage treatment pond for dealing with.
Palm oil mill process of palm kernel recovery : Press cake broken by breaking screw conveyor and then transported into the fiber separation air net and fiber polishing roller for fiber separating. The separated fiber material is sent to the boiler room as fuel; the separated stone is transported to stone warehouse by pneumatic conveying system for temporary storage.The kernel recovery process will utilize efficient ripple mills for nut cracking and a combination of two stages -- cracked mixture winnowing followed by wet separation by Clay bath for efficient kernel recovery.
Products from oil mill process (Lorestani 2006)
Simple Material Balance
Potential Products that Palm Oil Mill Waste Can Be Converted Into
The figure shows that palm oil mill waste may no longer be regarded as waste! Instead, it may be a source of wealth with the right technology, investment and proper management. In fact, all of the products shown above are not based on pipe dreams or the results of pilot projects, but are viable products from the palm oil industry.
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