The dewaxed oil-containing slurry may then be fed directly to wax filters without having to pass through scrapedsurface chillers and filter feed drum. Some of the propylene remains in the oil which serves to further dilute and reduce the viscosity of the slurry. Per minute with an average temperature drop across each stage of between about 2* and 20* F. 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 stagewise contact with liquid autorefrigerant preferably propylene, more » 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* to 20* F. A typical solvent extraction unit has been studied for enhancing quality and quantity of value-added products like lube base stock, wax, carbon black feed stock (CBFS) and bitumen.A continuous autorefrigerant solvent dewaxing process is disclosed wherein a waxy oil is prediluted with a nonautorefrigerative 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. 674) are replacing the traditional solvent refining processes, valuable products like wax, carbon black, and bitumen are available only from solvent refining processes.
Thermal and Catalytic Processes, : 674– 677. Hydroisomerisation of lube oils and medium fractions. Lubricant Base Oil & Wax Processing, : 81– 194. Though modern catalytic aromatic saturation and dewaxing ( Sequeira and Dekker, 1993a Sequeira, A. Finally this dewaxed oil is selectively hydrogenated to remove unwanted sulfur, nitrogen, and oxygen and also for improving color. In order for the pour point to be improved, selective removal of paraffin wax is carried out in a solvent dewaxing unit. 153) next to selectively dearomatize the distillates to yield high viscosity index (VI) oil. Solvent dewaxing & wax deoiling processes. Solvent refining of lubricating base oil stocks. Solvent extraction takes place ( Sequeira and Dekker, 1993c Sequeira, A. Highly viscous distillate is also recovered from the vacuum residue. In a typical lubricating base oil–producing refinery, viscous distillates from intermediate to heavy are available from such a unit. Reduced crude oil (RCO) from the atmospheric distillation unit is further distilled under a vacuum, yielding varieties of distillates like vacuum gas oil and light to heavy viscous distillates. In a refinery, crude petroleum oil is distilled in an atmospheric column to separate fuel gases and distillates.
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