Rapeseed Oil Production Line

1. 🌾 Pre-treatment Section

The effectiveness of pretreatment directly affects the oil yield and oil quality. The core steps include:

• Cleaning: Use equipment such as magnetic separators, vibrating screens, and destoners to remove impurities such as mud, stones, and metal shavings from the rapeseed. The purpose is to protect downstream equipment, reduce wear, and prevent foreign matter from contaminating the oil.
• Rolling: Using equipment such as a double-roll mill, rapeseed is rolled into thin sheets, which greatly increases the surface area and completely destroys the cell structure of the oilseed, making the oil easier to extract in subsequent processes.
• Steaming and roasting: This is a key step in the hot pressing and pre-pressing extraction process. Layered steaming and roasting pans are commonly used for moistening and roasting. By adjusting the moisture content and temperature of the raw material, the purpose is to stimulate the aroma of rapeseed, denature proteins, coagulate oils, and adjust the raw material to a suitable state for pressing.

2. ⚙️ Pressing process

Pressing methods can be divided into hot pressing and cold pressing, depending on whether steaming or roasting is involved:

• Hot pressing process: The steamed and roasted raw material is fed into a screw press and pressed under high temperature and pressure. It is characterized by a high oil yield and rich oil aroma, but the high temperature may cause some nutrient loss.
• Cold pressing process: After cleaning, rapeseed is pressed directly by a screw oil press or a special cold press at a relatively low temperature (e.g., 60-70℃) without heat treatment or only after low-temperature conditioning. This process better preserves natural nutrients such as vitamin E, sterols, and polyphenols, resulting in a lighter-colored oil with a refreshing flavor.
• Filtration: The crude oil obtained by pressing needs to be filtered by equipment such as plate and frame filter press to remove solid cake residue.

3. 🔬 Leaching process

To achieve high oil yield, large-scale production often employs the "pre-pressing-extraction" method:

• Pre-pressing: The steamed and roasted raw material is first pre-pressed by a screw oil press to extract most of the oil, resulting in pre-pressed cake (with a residual oil content of about 12%-18%).
• Leaching: The pre-pressed cake is fed into an extractor (horizontal, ring, or drag chain type) and soaked in solvents such as n-hexane to dissolve residual oils.
• Solvent recovery: The oil-containing mixed oil is heated in an evaporator and stripping tower to separate the solvent and obtain crude oil. The solvent vapor is condensed and recycled. The wet meal is then desolventized by a solvent descrambling unit (DTDC) to obtain the finished meal.

Leaching system technical parameters:

• Residual oil content: ≤ 0.5% (extremely high extraction rate)
• Solvent consumption per ton: ≈ ​​1.5 kg/t (extremely low consumption, high economic efficiency)
• System recycling rate: ≥ 99.5% (safe and environmentally friendly)
• Thermal energy utilization rate: Increased by 10%–15% (energy saving and consumption reduction)

4. 🧪 Refining Section

Crude oils extracted by pressing or solvent extraction need to be refined before they can be consumed. Typical processes include:

• Degumming: After heating the crude oil, water or dilute acid is added to remove phospholipids and other colloidal impurities through hydration or acid refining.
• Deacidification: Add food-grade sodium hydroxide solution to the oil or neutralize and remove free fatty acids through physical distillation.
• Decolorization: Activated clay or activated carbon is added to the decolorization tower to adsorb pigments (such as chlorophyll), residual soap residue, and trace contaminants in the oil.
• Deodorization: Under high temperature and high vacuum conditions of 220-240℃, it efficiently removes odor substances and peroxides from oils, significantly improves the smoke point and oxidative stability of oils, and achieves the standards of "zero trans fatty acids" and "zero glycidyl esters".
• Winterization degreasing (optional): After cooling and crystallizing the oil, filter it to remove solid grease and improve the clarity and brightness of the appearance.

🎯 Process Comparison and Selection Recommendations

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