Abstract: 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 stagewise contact with liquid autorefrigerant 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.degree. to 20.degree. F. per minute with an average temperature drop across each stage of between about 2.degree. and 20.degree. F.
Abstract: A continuous, combination ketone-autorefrigerant solvent dewaxing process is disclosed wherein a waxy oil is partially solvent dewaxed to within from about 30.degree. to 110.degree. F. of the final wax filtration temperature in a first chilling zone, preferably comprising a plurality of agitated stages in the presence of a ketone dewaxing solvent to form a slurry containing solid wax particles, partially dewaxed oil and solvent. This ketone-containing slurry is passed to a second chilling zone, which is an autorefrigerant chilling zone, preferably employing liquid propylene operates on a continuous basis, and comprises a vertical, multi-staged tower, operating at constant pressure, wherein additional wax is precipitated from the slurry. In the second chilling zone the slurry is chilled down to the wax filtration temperature by stagewise contact with liquid 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.
Abstract: 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.
December 27, 1978
Date of Patent:
June 17, 1980
Exxon Research & Engineering Co.
John H. Blume, James D. Bushnell, Milton D. Leighton
Abstract: A process for the combined hydrodesulfurization and hydroconversion of certain heavy hydrocarbon feedstocks is disclosed. Specifically, asphaltene-containing feedstocks, such as residua feedstocks, are initially contacted with a hydrodesulfurization catalyst which selectively avoids the conversion of the asphaltene agglomerates and metal-containing compounds therein, so that said feedstock is at least partially desulfurized, and then is contacted with an alkali metal in a conversion zone at elevated temperatures and in the presence of added hydrogen so that said feedstock is both further desulfurized and hydroconverted, preferably so that at least about 50 percent of the 1050.degree.F+ portion of the feedstock is converted to lower boiling products.