Distillates leaving the vacuum distillation unit contain such significant quantities of wax that they are solid at room temperature. Removal of the wax from the lubricating base oil is necessary for the base stocks to have the required low temperature properties. The BHTS solvent dewaxing process uses a mixture of MEK and toluene to aid in the crystallization and filtration of wax from the lube oil stocks.
Figure 6: Solvent Dewaxing Process

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|
Investment (basis: 7,000 pbsd, 2012 US Gulf Coast |
|
| US $/bpsd | 16,500 |
| Typical Utility Consumption (per bbl feed) | |
| Fuel, absorbed 103 Btu | 280 |
| Electricity, kWh | 46 |
| Steam, lb | 60 |
| Water, cooling (25oF termperature rise), gal | 1,500 |
| Solvent Makeup, lb | 0.6 |
Several recent developments have led to improved filtration rates, energy efficiency, water management, and operability of solvent dewaxing units. These include: