Dehazing a lubes product by integrating an air separation unit with the dehazing process

Abstract

A cryogenic air separation unit (ASU) is integrated into a lube oil dehazing process whereby waste nitrogen from the ASU is used to cool a lube oil base stock to promote the agglomeration and separation of haze-forming constituents in the base stock. Advantageously, the ASU may be part of a gas-to-liquid plant.

1 . An integrated air separation and a lube oil base stock dehazing process comprising:
 cryogenically separating an air stream in an ASU to provide an oxygen stream and two nitrogen streams, one being a nitrogen-enriched stream (utility nitrogen) and the other a nitrogen-reduced stream (waste nitrogen);   cooling a lube oil base stock with at least a part of the waste nitrogen stream to a temperature and for a time sufficient to promote the agglomeration and separation of haze-forming constituents in the base stock; and   separating the haze-forming constituent from the oil whereby a dehazed oil is obtained.   
     
     
         2 . The process of  claim 1  wherein the base stock is a heavy oil derived from a F-T wax. 
     
     
         3 . The process of  claim 2  wherein the base stock is at a temperature in the range of about 5° C. to about 125° C. 
     
     
         4 . The process of  claim 3  wherein the base stock is cooled at a rate of about 0.001° C./min. to about 10° C./min. 
     
     
         5 . The process of  claim 4  wherein the ASU includes an air prepurification absorber periodically requiring regeneration, the process including transferring a portion of the nitrogen used for cooling the base stock to the prepurification absorber during regeneration to reduce heater requirements for regeneration. 
     
     
         6 . The process of  claim 1  wherein the haze-forming constituents are separated by filtration on a filter medium. 
     
     
         7 . The process of  claim 6  including periodically regenerating the filter by purging the filter medium with a part of the waste nitrogen from the ASU. 
     
     
         8 . The process of  claim 1  including transferring the oxygen stream from the ASU to a syngas generator for use in conversion of a gaseous carbon-containing feed therein to syngas. 
     
     
         9 . The process of  claim 1  including using a portion of the waste nitrogen to provide cooling within the ASU. 
     
     
         10 . An integrated reaction system for forming dehazed lubricating base oils comprising:
 (a) an ASU for cryogenically separating air into an oxygen stream and two nitrogen streams, one being a nitrogen-enriched stream (utility nitrogen) and the other a nitrogen-reduced stream (waste nitrogen);   (b) a syngas generator in fluid communication with the ASU in which a gaseous hydrocarbon contacts at least a portion of the oxygen steam under conditions sufficient to convert the hydrocarbon to syngas;   (c) a hydrocarbon conversion unit in fluid communication with the syngas unit wherein syngas contacts catalyst composition under conditions sufficient to convert at least a portion of the syngas to waxy paraffinic hydrocarbons;   (d) an upgrading unit for converting the waxy paraffinic hydrocarbon to high boiling lube oil base stock;   (e) a haze incubation unit in fluid communication with the ASU in which at least a part of the waste nitrogen stream is passed in heat exchange relationship with the heavy lube oil base stock to cool the oil and promote the agglomeration and separation of haze-forming constituents in the base stock; and   (f) a haze removal unit in communication with the haze incubation unit for separating the dehazed base oil from the haze-forming constituents.   
     
     
         11 . The system of  claim 10  wherein the haze separation unit comprises a filter medium for collecting haze-forming constituents thereon, the system further comprising a conduit for periodically delivering a portion of the waste nitrogen from the ASU to purge the filter medium. 
     
     
         12 . The system of  claim 10  wherein the ASU includes an air prepurification absorber system that periodically requires heating for regeneration, the system further comprising a conduit for transferring waste nitrogen used in cooling the base stock in the haze incubation unit to a heater for regenerating the prepurification absorber thereby reducing heater requirements. 
     
     
         13 . The system of  claim 10  including fluid communication means for recycling a portion of the waste nitrogen to the ASU to provide cooling therein. 
     
     
         14 . The use of waste nitrogen from an ASU to cool a lube oil base stock to promote the agglomeration and separation of haze-forming constituents in the base stock. 
     
     
         15 . The use of  claim 14  wherein the lube oil base stock is derived from an F-T wax. 
     
     
         16 . The use of  claim 15  wherein a portion of the waste nitrogen is recycled to the ASU to provide cooling therein.