| 摘要 |
A continuous autorefrigerant solvent dewaxing process is disclosed wherein a waxy oil is prediluted with a non-autorefrigerative solvent, such as ketone, preferably a mixture of MEK/MIBK, and then passed, at a temperature above its cloud point, to the top of a chilling zone, which is an autorefrigerant chilling zone operating on a continuous basis, and comprises a vertical, multi-staged tower, operating at constant pressure. In this chilling zone, wax is precipitated from the oil to form a waxy slurry and the so-formed slurry is further chilled down to the wax filtration temperature by stage-wise contact with liquid auto-refrigerating preferably propylene, which is injected into a plurality of said stages and evaporated therein so as to cool the waxy slurry at an average rate of between about 0.1 DEG to 20 DEG F. per minute with an average temperature drop across each stage of between about 2 DEG and 20 DEG F. Some of the propylene remains in the oil which serves to further dilute and reduce the viscosity of the slurry. The dewaxed oil-containing slurry may then be fed directly to wax filters without having to pass through scraped surface chillers and filter feed drum.
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