Introduction
Caustic refining is a process that chemically neutralizes crude vegetable oils and fats. It consists in mixing the oil with caustic soda, which saponifies the fatty acids present in the oil, and in removing this precipitate by centrifugal separation.
A preliminary step will allow the transformation of the non-hydratable phospholipids into hydratable form thanks to the action of a strong acid (usually phosphoric or citric). The phospholipids are then complexed by water present in the caustic soda solution and they will be separated from the oil together with the soapstock.
Remaining soaps are further reduced by washing the oil with hot process water (or by silica treatment).
This process is well suited to most edible oils and gives first class edible end products at the outlet of the refinery.
To obtain first quality oils, it is essential to make sure that the crude oils entering the deodoriser are free of impurities. Caustic neutralizing and bleaching are the necessary processes that yield such purified oil.
Chemical refining of unsaturated oils, like soybean oil, sunflower oil, corn oil, etc..., comprises 3 steps:
- Acid conditioning step
- Neutralization step
- Water washing (or silica treatment) step
Usually, only two separators are used, one for removing gums and soapstock and one for the washing step. It is largely enough for most oils and it reduces investment, effluents as well as maintenance.
Nano Neutralization™
Based on patented technology developed by CTi and exclusively brought to the oils and fats industry by Desmet, the Nano Neutralization™ process offers enhanced performance for the neutralization refining operation: improved oil refining yield, lower operating expenses, reduced environmental impact and excellent oil quality.
This revolutionary new oil neutralization process, which can be easily added to existing oil refineries, is commercially proven and will offer a quick return on investment.
Nano Neutralization™ is an add-on process to an existing oil refinery neutralization system, which has the potential to improve oil yield, save phosphoric acid, save caustic, save wash water (or silica) and perhaps save steam and bleaching earth.
CTi Nano® Reactor
A CTi Nano® Reactoris a static device with no moving parts. Its name is due to the creation of nanometer sized bubbles while the fluid is pumped through the CTi Nano® Reactor under high pressure. The CTi Nano® Reactor creates intense hydrodynamic cavitation with shockwaves that break the weak bonds of the Ca and Mg non-hydratable phospholipids in milliseconds.
Vegetable oil is pumped through a series of scientifically designed geometries. At each stage, there is a dramatic pressure drop. The water molecules in the oil vaporize and recompress to a liquid at each stage, creating shockwaves that break the weak metal bonds of non-hydratable phospholipids to make them more hydratable. In addition the CTi Nano® Reactor thoroughly mixes acid and caustic solutions that have been added to the crude vegetable oil.
Advantages
The main advantages of the Desmet Nano Neutralization™ process are as follows:
Oil yield can be improved via improved separation of the heavy phase from the light phase in the neutralizing centrifugal separator as a result of conditioning the oil in the CTi Nano® Reactor. Less neutral oil remains in the heavy phase, thus improving yield.
Phosphoric acid can be saved via conditioning the oil in the CTi Nano® Reactor which converts most of the non-hydratable phospholipids to a hydratable form. By accomplishing this task in Nano Neutralization™, the upstream phosphoric acid addition can be substantially reduced or totally eliminated.
Caustic can be saved because phosphoric acid is significantly reduced and a stoichiometric amount of caustic is used strictly to neutralize the phosphoric acid. Caustic can be further reduced due to improved mixing of the caustic-water solution into the oil inside the CTi Nano® Reactor.
Wash water (or silica) can be saved via improved separation of the heavy phase from the light phase in the neutralizing centrifugal separator as a result of conditioning the oil in the CTi Nano® Reactor. Less soap remains in the light phase, thus reducing the need for wash water (or silica) downstream to remove this residual soap. Less wash water (or silica) also directly results in less oil loss in the spent wash water (or spent silica).
Steam can be saved in those refineries that presently heat the oil above centrifugal separation temperature during the acid pre-treatment step to increase acid reactivity. With Nano Neutralization™ there is not a need to warm the oil above centrifugal separation temperature, thus saving steam.
Nano Neutralization™ there is not a need to warm the oil above centrifugal separation temperature, thus saving steam.