Effect of Increased Raffinate VI

Raffinate VI may be increased in extraction through more severe extraction. This increases wax concentration in the raffinate stream. These waxy molecules will come out of solution in the dewaxer at a higher temperature, resulting in the miscibility curve shifting to the left. This will require the manufacturer to add more prosolvent to avoid immiscible operation. 

8 Effect of Pour Point Giveaway on Product Quality and Dewaxed Oil Yield 

When a Basestock produces a dewaxed oil with a lower pour point than the specification, the plant is giving away this product quality. The economic penalty for pour point give away is lower filtration rate and lower throughput and decreased dewaxed oil yield. Lower pour point also means that more wax has been removed and this will lower the dewaxed oil VI. 

Base Stock Pour Point Typical VI Loss Typical Yield 

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