The process from crude palm oil to refined oil mainly includes the following steps:

Crude oil filtration:

The purchased crude palm oil first needs to be filtered to remove suspended particulate impurities and other visible impurities to provide relatively pure raw oil for the subsequent refining process, ensuring the smooth progress of the subsequent refining process and the quality of the refined oil.

Degumming:

Principle: Palm crude oil contains phospholipids, sugars, protein mixtures, trace metals and other impurities. The presence of these impurities will affect the quality and stability of the oil. Degumming is the process of removing these peptizing impurities.

Operation: usually add phosphoric acid to crude oil heated to 90 - 105°C, mix vigorously for about 3 minutes, and then use dilute alkali to neutralize part of the phosphoric acid. Then, all the fat is separated with a centrifuge, then the water is heated and left to stand, and centrifugation is performed using particularly high gravity acceleration. After this series of operations, the phospholipid content in the degummed oil can be reduced to less than 5×10⁻⁶.

Neutralization (deacidification):

Principle: Neutralization and deacidification are mainly to reduce the acidity in oil. There is a certain amount of free fatty acids in palm crude oil, which will affect the quality and stability of the oil. By adding alkali solution and neutralizing the free fatty acids, the free fatty acids are removed.

Action: Add caustic soda or soda ash to the oil to neutralize free fatty acids. Caustic soda can not only react with fatty acids to form soap stock, but also absorb some other impurities to improve the quality of grease. Soapstock is generally separated by centrifugation. However, the chemical neutralization method produces soap stock and wastewater, which requires subsequent treatment.

Depigmentation:

Principle: Use the adsorption effect of adsorbents (such as activated clay) to remove pigments in palm oil and other impurities dispersed in the oil as colloidal particles, thereby improving the color, flavor and oxidation stability of the oil, and further refining the oil. , hydrogenation and deodorization provide good conditions.

Operation: The grease is measured and preheated to 80 - 90°C, premixed with activated clay, and then sent to the decolorization tower for decolorization. The separation of oil and waste clay after decolorization adopts filtration method. In China, vertical blade filter and plate and frame filter are often used for continuous decolorization of oil.

Deodorization:

Principle: Inject high-temperature water vapor into palm oil under vacuum conditions to take away the odor substances in the oil and make the oil smell more pure.

Operation: The deodorization temperature is generally controlled at 230 - 250°C, and the residual vacuum pressure is 6 - 8 mmHg. In order to prevent oxidation, it must be degassed before entering the tower. Direct steam can be introduced to improve the deodorization effect. At the same time, heat energy can be recovered through heat exchange between cold oil and hot oil, reducing energy consumption.

Fractionation (optional):

This is a special processing step for palm oil. When palm oil is cooled to a certain temperature (usually a lower temperature) and maintained for a certain period of time, the components with high melting points will crystallize and precipitate. After secondary filtration, they can be "fractionated" into three products with different melting points, namely Palm stearin (melting point higher than 40°C), palm soft fat (melting point around 30°C) and liquid palm oil (melting point below 20°C).

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