What is the working principle of the deodorization tower
Information summary：Deodorization tower is the core equipment in the refining process of edible oils and fats. Its working principle is based on the physical separation mechanism of steam distillation (stripping)+high temperature and high vacuum. By utilizing the large difference in volatility between small molecule odor substances (aldehydes, ketones, alcohols, free fatty acids, solvent residues, sulfides, etc.) in
Deodorization tower is the core equipment in the refining process of edible oils and fats. Its working principle is based on the physical separation mechanism of steam distillation (stripping)+high temperature and high vacuum. By utilizing the large difference in volatility between small molecule odor substances (aldehydes, ketones, alcohols, free fatty acids, solvent residues, sulfides, etc.) in oils and fats and triglycerides, the odor substances are preferentially evaporated in high temperature and high negative pressure environments. Then, through superheated steam stripping+vacuum extraction, the purpose of odor removal, flavor improvement, and stability enhancement is achieved.
1、 Core principle
Under high vacuum (0.27-0.40 kPa) and high temperature (230-270 ℃) conditions:
Vacuum significantly reduces the boiling point of odorous substances, making them much lower than the decomposition temperature of oils and fats, making them more prone to volatilization.
Inject superheated dry steam into the oil, and the steam serves as a stripping medium. When passing through the oil layer, it fully contacts and saturates with the volatile odor components, forming "odor steam".
Using the principle of partial pressure, odorous substances escape from the oil phase with steam and are continuously extracted and condensed for recovery by the vacuum system.
Triglycerides have low volatility and are almost non-volatile under these conditions, achieving efficient separation without odor or oil.
2、 Typical working process (combination deodorization tower, mainstream in the industry)
The combined deodorization tower is divided into an upper packing section and a lower plate section for continuous operation:
Oil distribution: After decolorization, the hot oil enters from the top of the tower and is evenly distributed on the surface of the packing through the oil separator, forming a very thin oil film (about 10 μ m), greatly expanding the mass transfer area.
Packing section stripping (pre deodorization/deacidification): The oil film is in reverse contact with superheated steam from bottom to top, rapidly removing most of the free fatty acids, low molecular weight odors, and residual solvents, which are then evacuated by vacuum.
Deep deodorization and thermal decolorization in the plate section: Oil flows into the lower plate section, and direct steam bubbling is introduced into each tray to enhance stripping; Stay under high temperature and high vacuum for a certain period of time (about 30 minutes) to further remove trace odors, while completing thermal decolorization to improve color and oxidation stability.
Oil extraction and heat exchange: The qualified deodorized oil is discharged from the bottom of the tower and preheated by the waste heat recovery heat exchanger before entering the tower for cold oil, reducing energy consumption; Cool down to a safe temperature and proceed to the next process.
3、 Key process conditions
Working temperature: 230-270 ℃ (adjusted according to the type of oil to avoid overheating and oxidation)
Operating pressure: 0.27-0.40 kPa (absolute pressure), high vacuum is the core of low boiling point volatilization
Steam extraction: superheated, dry, oxygen free; Dosage: 0.5% -1.5% for packed tower, 1.5% -3% for plate tower, 5% -8% for intermittent tower (for oil weight)
Deodorization time: 20-40 minutes for continuous tower to ensure sufficient odor removal and thermal decolorization effect
4、 Main functions and effects
Remove odors such as free fatty acids, solvent residues, burnt, green, fishy, metallic, etc
Reduce acid value, improve color, enhance oxidation stability and smoke point
Physically refined, without adding chemical reagents, retaining the natural nutrition and flavor of the oil
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