Rapeseed oil refining process

Rapeseed oil is a semi-dry oil containing erucic acid. Except for low erucic acid rapeseed oil, other varieties of rapeseed oil contain more erucic acid, which accounts for about 26.3%~57% of the fatty acid composition. High erucic acid rapeseed oil is not as nutritious as low erucic acid rapeseed oil, but it is especially suitable for making marine lubricants and industrial oils such as tires. During the oil making process, myrosinase is hydrolyzed by myrosinase to form some sulfur-containing compounds and other toxic components, which affect the quality of crude oil. The general rough refining process has a very low removal rate of sulfide, so edible rapeseed oil should be refined.

1. Crude rapeseed oil refining process

For the technical process and operating conditions of crude rapeseed oil, please refer to soybean oil crude refining.

2. Process flow of refined rapeseed salad oil refining (intermittent)

Alkaline rich oil soapstock-→salting out-→lean oil soapstock

↓ ↑

Filter rapeseed oil-→preheating-→neutralization-→stationary sedimentation-→separation-→washing←-soft water

↓

Filtration←-distillation deodorization←-filtration←-adsorption decolorization←-dehydration

↓ ↓ ↓ ↑ ↓

Refined vegetable oil Water vapor Waste clay Adsorbent Waste water

Operating conditions: initial operating temperature of alkali refining is 30~35°C, final temperature is 60~65°C, lye concentration is 16°Bé, excess alkali addition is 0.2%~0.25% of oil volume, plus 0.5% of oil volume The neutralization time is about 1 h, and the sedimentation separation time is not less than 6 h. Alkali refining washing temperature is 85~90℃, the first washing water is dilute saline alkaline water (0.4% lye concentration, 0.4% salt added to the oil), and the added amount is 15% of the oil. After that, wash it several times with hot water until the soap content in the alkali refining oil is not more than 50 ppm. When decoloring, first vacuum dehydrate for 30 minutes, the temperature is 90°C, and the operating absolute pressure is 4.0kPa, then add activated clay for decolorization, the amount of clay added is 2.5%~3% of the oil, the decolorization temperature is 90~95°C, and the decolorization time is 20 minutes, then Cool to below 70 ℃ and filter. The decolorized and filtered oil is sucked into the deodorization tank by the vacuum formed by the first and second stage steam jet pumps and heated to 100°C, and then the third and fourth stage steam jet pumps and the cooling water of the atmospheric condenser are turned on, and the deodorization temperature is not lower than 245°C. The absolute pressure is 260~650Pa, the water temperature of the atmospheric condenser is controlled at about 30°C, the direct steam pressure of the stripping is 0.2MPa, the feed rate is 8~16 kg/t h, the deodorization time is 3~6 h, and the deodorization is completed and cooled in time to Filter at 70°C.

2. Refining process of refined rapeseed salad oil (full continuous)

phosphoric acid lye

↓ ↓

Filtration of crude oil-→preheating-→mixing-→oil-alkaline ratio-→mixing reaction-→desoaping-→soap stock

↓

Filtration←-distillation deodorization←-filtration←-adsorption decolorization←-drying←-dehydration←-washing←-soft water

↓ ↓ ↓ ↑ ↓

rapeseed salad oil water vapor waste clay adsorbent waste water

Operating conditions: filtered crude oil contains no more than 0.2% impurities, lye concentration is 18~22°Bé, excess alkali addition is 10%~25% of theoretical alkali amount, and sometimes 0.05%~0.20% of oil amount is added first Phosphoric acid (concentration is 85%), the soap removal temperature is 70~82℃, the washing temperature is about 95℃, and the amount of soft water added is 10%~20% of the oil. Continuous vacuum drying and dehydration, the temperature is 90~95℃, and the operating absolute pressure is 2.5~4.0 kPa. The adsorption decolorization temperature is 105-100°C, the operating absolute pressure is 2.5-4.0 kPa, the operation time at the decolorization temperature is about 30 minutes, and the amount of activated clay added is 1%-4% of the oil volume. The filtration temperature when using the vertical blade filter to separate white clay is not lower than 100°C. P≤5 ppm, Fe≤0.1ppm, Cu≤0.01ppm in decolorized oil. The deodorization temperature is about 240~260℃, the operating absolute pressure is 260~650Pa, the stripping steam feed rate is 0.5%~2% of the oil volume, the deodorization time is 40~120min, and the citric acid (concentration 5%) is 0.02% of the oil volume. %~0.04%, the safe filtration temperature is not higher than 70°C.