Oil expellers ( also known as mechanical screw presses) are generally used for the purpose of extracting oil from various oil seeds, beans, nuts etc. The term oil expeller encompasses full press extraction expellers as well as pre press extraction expellers, with the full press ones being generally used by small and medium capacity oil mill plants and pre press ones being commonly used by large capacity plants. It would suffice to say that oil expellers are the central part of any
oil extraction plant, with important parameters such as production
capacity, quality of the produce depending solely on the expellers.
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| Oil Expeller |
Working Principle
The major parts of an oil expeller are the helical screw, cashing and the linings. During the functioning of the expeller, the helical screw moves the material, thus compressing it and producing the cake. The volume of oil keeps reducing while the transition takes place through the barrel of the cashing. This causes further compression of the cake which results in the production of oil. The produced oil then comes out through the linings in the expeller, while the de-oiled cake is discharged. An oil expeller can generally be operated through the use of electric motor, diesel and also a human powered flywheel.
Salient Features of Oil Expellers
The major parts of an oil expeller are the helical screw, cashing and the linings. During the functioning of the expeller, the helical screw moves the material, thus compressing it and producing the cake. The volume of oil keeps reducing while the transition takes place through the barrel of the cashing. This causes further compression of the cake which results in the production of oil. The produced oil then comes out through the linings in the expeller, while the de-oiled cake is discharged. An oil expeller can generally be operated through the use of electric motor, diesel and also a human powered flywheel.
Salient Features of Oil Expellers
- These have a simple construction and are easy to operate, with the requisite safety features for the operator present
- Most oil expellers are very power efficient, thus providing incremental cost benefits in the long run
- These are resistant to weathering, i.e. – can operate flawlessly in all weather conditions
- These are also resistant to corrosion, abrasion, moisture and UV rays
- Oil expellers are generally portable, i.e. – these can be moved from one facility to another
- These have a long functional life and require minimal maintenance
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| Oil Expellers |
Preparation of Raw Materials for Use in Oil Expellers
- Raw materials such as oil seeds, nuts should always be properly cleaned and dried before to prevent contamination. Moreover, some raw materials such as palm kernels require to be grinded in mills before being used in oil expellers
- Afterwards, all raw materials should be very carefully sorted so as to remove stones and sand particles
- If storage is required, it should always be done in weatherproof and ventilated rooms.
- Apart from all of the above, some husk is also added to the expellers so as to allow oil to escape more freely from them
Modes of Operation of Oil Expellers
Primarily there are two major modes of operation of oil expellers. To elaborate,
Primarily there are two major modes of operation of oil expellers. To elaborate,
- Cold press mode – The distinguishing feature of this mode is that the incoming seed is fed without preheating it to the expeller. In this mode, the cake produced is of very good quality but it has a negative effect on the oil yield of the seed, thus compromising it.
- Hot press mode – In this mode, the incoming seed is first preheated and then fed to the expeller. Unlike in the cold press mode, the quality of the cake produced is not that good but there is a marked increase in oil yield of the seed
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