Specific operation method for refining sesame seed oil

(1) Before the sesame seed oil is quickly pumped into the refining tank by the filter press crude oil pump, it is necessary to check whether the pipeline valves are normal. After each tank completes the oil delivery, the oil inlet valve should be immediately closed. For crude linseed oil to be refined in the oil tank, the foam on the oil surface must be removed first to make the oil surface smooth, and it should be left standing for an appropriate time (not less than 15min) to make the oil free of foam. Adjust the crude oil temperature to 25-35 ℃.

(2) Mix the specified amount of NaOH (purity must be verified first) into an appropriate amount of water and stir. Start the alkali pump and circulate the alkali solution to completely dissolve the NaOH. Lower the temperature of the alkaline solution to 25-30 ℃, let it stand for 20 minutes, measure the Baume degree of the alkaline solution with a Baume meter, and adjust it to 10-12 ° Be.

(3) Mix alkali until the crude oil surface is smooth and the temperature stabilizes at 25-35 ℃. Start the mixer and stir slowly (20r/min) for 1 minute, then switch to fast (40r/min). While stirring, open the alkali tank valve and add alkali solution. The usual time for adding alkali solution is about 15 minutes. After adding the alkali solution, continue to stir at a fast speed until the oil and soap particles are clearly separated. The stirring time is about 3-3.5 hours. When the oil and soap feet are clearly separated, change to slow stirring, open the heating steam valve (vapor pressure 1.4kgf/C ㎡), raise the temperature of the oil to 60 ℃ (the oil temperature should be kept at 1 ℃/min, and the highest temperature should not exceed 65 ℃), immediately stop stirring, and close the steam valve to allow it to cool and precipitate on its own (precipitation time is about 8 hours). After checking that the oil delivery valve pipeline is normal, pump the oil into the water washing tank. When the pump reaches the interface between the oil and the settled soap feet, it must be highly careful not to pump out the soap feet, and at the same time, the oil pump must be pumped out.

(4) Wash the oil pumped into the washing tank and heat it up. At the same time, start the mixer to add hot water at 75-80 ℃ to maintain the oil temperature at 80-85 ℃ (the temperature should not exceed 85 ℃). When the water is added (the amount of water added is 15% -20% of the oil amount, and the water addition time is 38-40 minutes), stop heating and continue stirring for 15 minutes, then stop stirring and settle for 2 hours (the first time). Open the drain valve at the bottom of the washing tank and release about 3/4 of the washing water (before releasing the washing water, top the oil stored in the pipeline into the oil-water separation tank for recovery). Then close the drain valve, open the valve leading to the oil-water separation tank, and slowly add the remaining oil-water mixture. When washing for the first time, all the viscous substances in the oil-water intermediate layer must be placed in the separation tank until good oil is seen, and then the valve should be closed.

Oil water separation must be controlled by a dedicated person. When separating in the separation tank, the heating coil inside the tank must be turned on to increase the temperature (not exceeding 80 ℃). After separation, the water should be released and the residual oil should be recovered.

Continue washing the oil machine with water according to the above method until the washing water is completely clear, and the sedimentation time for the second washing is 1.5 hours.

(5) Before dehydrating and transporting, check whether the relevant pipeline valves are normal. Then, pump the water washed bin into the vacuum dehydration tank, open the steam valve, start the vacuum pump and mixer, adjust the cooling water of the condenser, and start the circulating oil pump to accelerate the circulation of oil in the vacuum dehydration tank. The vacuum degree of the vacuum dehydration tank is maintained above 0.0867MPa. The dehydration time is about 3 hours. Starting from the delivery of oil from the dehydration tank, the dehydrated oil needs to be sampled and inspected by a quality inspector. When insufficient dehydration is found, dehydration must continue. The dehydration temperature is maintained at around 70 ℃.

Dehydration is complete, stop the vacuum pump, open the air valve, and slowly introduce air. Check if the pipeline valves are normal, and then transport the oil through the cooling pipe to cool to 25-30 ℃ before flowing into the settling tank for pressure filtration.

(6) Check if the pressure filter pipeline valve is normal. The oil temperature must be checked to be below 30 ℃. After the oil is filtered, stop the oil filter pump and close the valve. Gently open the filter plate to allow the internal oil to flow into the oil pan, and then remove the filter residue on the filter cloth. Check the usage of the filter cloth and prepare to replace or wash it. The residual oil in the filter cloth should be separated and recovered using a centrifuge.

(7) Residual oil recycling and utilization of oil-water separation tank, separating the recovered oil and refining it again. Filter cloth with residual oil, folded neatly and evenly, placed in a centrifuge, separated, and the residual oil collected for re refining. When operating a centrifuge, it is necessary to strictly control the speed of the centrifuge, gradually increasing from slow to fast during startup. If it is necessary to stop halfway during rotation, the motor should be stopped. However, if the centrifuge is not completely stationary, it is absolutely not allowed to close the switch and continue to operate.

The amount of caustic soda added and the concentration of alkaline solution depend on the acidity and impurity content of the filtered crude sesame seed oil. If the acid value is high, the amount of alkali required to neutralize free fatty acids should be high and the concentration should be high. If the acid value is low, the amount of alkali required should be small and the concentration should be low. When there are many impurities, there should be more excess alkali added. According to the impurity content of sesame seed oil, the excess alkali content is generally 0.1% -0.2%. However, the components contained in the crude oil are complex, such as acidity and impurities, which determine the amount and concentration of alkali used. Sometimes, this may not necessarily yield good results, so it is best to conduct a small cup test before refining. The temperature for adding alkali should not be too high. After neutralization with alkali, increase the oil temperature to break its emulsified state and completely separate the soap particles from the oil. The stirring speed during alkaline neutralization should be fast to ensure sufficient contact between the alkaline solution and the oil, and to quickly neutralize the free fatty acids in the oil. After the free fatty acids are completely neutralized, stirring should be slow during the heating period to prevent the formed soap particles from being broken into small particles that are difficult to sink. Then wash with water to remove trace soap particles and free bases dissolved in the oil. After washing with water, flaxseed oil has a high moisture content (0.3%), which can easily cause changes in quality during storage, so dehydration is necessary. The final refining process is cold cooling and pressure filtration to remove wax substances from the oil.