Principles: in concentrated miscella direct steam after flowing a small amount, can reduce the boiling point of the solvent vaporization and vapor partial pressure. So that evaporation of the solvent mixture of oil residues, and was taken away along with the steam (stripping), has reached desolventizing purposes. Stripping unit: downstream rising film tube stripper; countercurrent falling film stripper disc; counterflow evaporative emergency flash, ramp down film and tower packing and so on. Which is used more often by the 10-18 group consisting of conical disc stacked stripper, high efficiency, high capacity, less consumption of steam.
Vacuum stripping of reasons:
Because of the high oil mixture into the stripping stage concentration (above 90%), at atmospheric pressure, even with direct steam to reduce the partial pressure of the gas phase, but still requires high desolvation temperature. General atmospheric vapor temperature of 110.5-142.8 ℃. Oil at a temperature above 135 ℃, it is easy oxidation, polymerization, decomposition of the peroxide and the thermal stability of many products.
General requirements for residual pressure in310-460mmHg (41.23-61.2kPa), vapor temperature controlled at 80-95 ℃. This ensures that affected the quality of crude oil in the phospholipids, facilitate the development of the use of phospholipid products.
1, the filter screen size: 100 mesh / in;
2, mixed oil temporary storage tank with a salt concentration of 5%; supernatant containing slag requirements <0.05%;
3, regular washing or recoil filter mesh, and promptly returned residue extractor; if found damaged timely repair or replacement;
4, evaporator, stripper should be cleaned regularly (2-3 months); the operation is found significantly worse effect, it must be stopped in time can only continue after inspection or cleaning; cleaning methods generally use direct steam erosion, if the wall the cumulative impact of grease or disc production, cooking with hot lye must 12-24h, and then use the direct steam clean.
Common faults and causes:
1, the evaporator is not oil, Miscella oil reserves because of insufficient tubing plug; Miscella oil trash content or more low vapor pressure, the amount of heat is not enough, the temperature can not go; separator produces flooding, separation unclear; condenser blockage;
2, resulting in flooding phenomenon, because the mixture of oil flow too overloaded; excessive waste impurities; vapor pressure fluctuations, temperature rises too fast, excessive mixing oil evaporation, vacuum is too high; Separator unclear or into the air caused by the internal pressure is too large;
3, evaporation is poor, because the sedimentation tank salt concentration is not enough;