The refining process of complete palm oil is: degumming, deacidification, decolorization, deodorization. Among them, deacidification is an important step in the palm oil refining process, and it is also an indispensable step. The quality of deacidification effect directly affects the quality and selling price of palm oil. So how can we do a good job in the deacidification section? What are the factors affecting palm oil alkali deacidification?
1. Alkali and its dosage
The base includes NaOH, KOH, Ca(OH)2, Na2CO3 and the like.
The total alkali consumption during alkali refining: the theoretical amount of alkali to neutralize free fatty acids; the excess alkali added to meet the process requirements.
2. Alkaline concentration
The choice of lye concentration is based on:
Acid value of crude oil (high acid value concentration, and vice versa);
Neutral oil saponification loss;
the consistency of the soapstock;
Operating temperature (high temperature light alkali, low temperature concentrated alkali);
Degree of decolorization of crude oil.
3. Operating temperature
Initial temperature: low temperature when adding alkali to avoid saponification of neutral oil.
Final temperature: Higher temperature during the oil-soap particle separation after the reaction can accelerate the coagulation of soap particles to release neutral oil and facilitate the separation of oil-soap particles.
The centrifuge operates continuously, and the separation temperature is generally 80-90°C. The mixing temperature of alkali addition is generally about 50°C.
4. Operating time
The influence of operating time on the effect of alkali refining is mainly reflected in the loss of saponification of neutral oil and the effect of comprehensive impurity removal. The longer the contact time between oil and alkali, the greater the probability of saponification of neutral oil; but it is beneficial to the removal of other impurities and the improvement of oil color.
5. Mixing and Stirring
When adding alkali, the intensity of mixing or stirring should be strong, so that the alkali solution is highly dispersed in the oil phase. When flocculating the soap particles, the mixing and agitation intensity should be gentle.
6. The influence of impurities
Such as peptizing impurities can promote alkali refining to produce lasting emulsification; such as gossypol and other pigments increase the amount of alkali used.
Soft water should be used to prepare alkaline solution.
The oil-soap separation effect depends on the flocculation of soapstock, soapstock consistency, separation temperature and settling time, etc. Continuous centrifugal separation is also affected by separator performance, material flow rate, feed pressure and light phase (oil) outlet pressure.
8. Washing and drying
Reduction of residual soap and free alkali in alkaline refining by hot water washing.
The washing operation temperature is generally about 85°C, and the amount of water added is 10% to 15% of the oil amount. The water for one wash can use a mixed dilute solution of salt and alkali, and reduce the stirring speed. To prevent emulsification.