Exxon Research and Engineering Company

John H Blume

James D Bushnell

Milton D Leighton

An improved process for removing H.sub.2 S from a hydrofiner tail gas wherein said tail gas is passed into a scrubbing zone wherein it is contacted with liquid NMP to remove most of the H.sub.2 S from the gas to form an H.sub.2 S-rich NMP solution and the H.sub.2 S-rich NMP solution is heated and passed into a stripping zone to remove most of the H.sub.2 S from the NMP to form an H.sub.2 S-lean NMP solution, extracting a hydrocarbon oil with an NMP solution, recovering hot liquid, NMP from said extracted oil and combining it with said H.sub.2 S-lean NMP solution and wherein said combined solution comprises at least a portion of said NMP solution used to extract said oil, wherein the improvement comprises heating the H.sub.2 S-rich NMP solution to the required stripping temperature by indirectly contacting same, in heat exchange relationship, with at least a portion of said combined NMP solution. This process is especially useful for scrubbing H.sub.2 S from hydrofiner tail gas for use as once-through stripping gas in the solvent recovery section of a lube oil extraction process employing NMP as the extraction solvent, and in a preferred embodiment, the spent stripping gas from the lube oil solvent recovery is used as the stripping gas in the stripping zone of this invention.

Removing H.sub.2 S from gas with recycled NMP extraction solvent

Autorefrigerative and ketone solvents are separated and recovered from dewaxed oil and wax through the use of high and low pressure flashes followed by steam stripping. Water buildup in the recovered solvent is prevented by the use of a decanter and deketonizer wherein the overheads from the strippers are sent directly to the deketonizer and the overhead therefrom sent to the decanter, thereby substantially reducing the size of the deketonizer required. Water is removed from the recovered solvent in the deketonizer and may be sent to sewerage.

Growing community of inventors

Chester, NJ, United States of America

John H Blume