Walnut Oil Processing Plant

Alkali Refining Operation

Begin by warming the oil to approximately 60°C. Then, methodically add an alkali solution of 20-30Be (composed of 1kg caustic soda and 5kg water) over 5-10 minutes. Stir the mixture at 60 rotations per minute for another 5-10 minutes and watch for the formation of soap particles, indicating a successful reaction.

As these particles separate, gradually increase the temperature by about 1°C per minute. Once the temperature hits 65°C and the oil-soap separation is clear, cease stirring to allow the soap stock to settle, a process that typically takes 4-6 hours before the soap stock can be released.

Washing Operation

Post soap stock removal, elevate the oil temperature to 75°C and introduce hot water amounting to over 5% of the oil's weight for washing. Ensure the water is 5-10°C hotter than the oil to prevent emulsification.

After adding the water, continue stirring for 5 minutes, then let the mixture stand for 3-4 hours. Drain the soapy water and repeat the washing 1-2 times as needed, based on the clarity of the oil.

Decolorization Operation

Activate the vacuum pump to achieve a vacuum of at least 700 mmHg. Transfer the alkali-refined oil into the decolorization tank under vacuum conditions. Begin stirring and gradually increase the temperature. After reaching 100°C, maintain stirring for 10 minutes to reduce the oil's moisture content below 0.1%.

Then, introduce a small quantity of a decolorizing agent (either white clay or activated carbon), typically 2%-4% of the oil volume. Stir for 20 minutes, cool to around 90°C, disengage the vacuum, and filter the mixture to separate the oil from the decolorizing agent, yielding a decolorized oil.

Deodorization Operation

Draw the decolorized oil into the deodorization tank using a vacuum. Once the vacuum reaches 755mmHg and the temperature exceeds 150°C, initiate direct steam distillation for deodorization. The key parameters for this stage are:

1. 1. Deodorization time: 2-3 hours.
2. 2. Deodorization temperature: 220°C-240°C.
3. 3. Deodorization vacuum degree: Above 755mmHg.
4. 4. The deodorization process is conducted under direct steam.