Hydrocarbon Extraction Processes Utilizing a Cleansing Bed

Abstract

Hydrocarbon extraction processes utilizing a cleansing bed to cleanse at least a portion of a lean-solvent stream are disclosed. The cleansing bed can preferentially include abed of activated carbon, abed of alumina, and/or a bed of an ion-exchange resin. The extraction process can use a liquid/liquid extraction column or an extraction distillation column. The process can be particularly advantageous for removing C10-C20 contaminants, among others, from the lean-solvent stream.

1 . A process for extracting aromatic hydrocarbons from a mixture feed comprising aromatic hydrocarbons and non-aromatic hydrocarbons, the process comprising:
 (A-1) feeding the mixture feed into an extraction column;   (A-2) providing a first lean-solvent stream comprising a polar solvent at a concentration of c(ps) wt %, and heavy components at a total concentration of c(hcom) wt %, based on the total weight of the lean-solvent stream, where 75≤c(ps)≤99.99;   (A-3) obtaining a cleansed first lean-solvent stream by (A3-a) contacting the first lean-solvent stream with a first cleansing bed comprising activated carbon; and   (A-4) feeding at least a portion of the cleansed first lean-solvent stream into the extraction column.   
     
     
         2 . The process of  claim 1 , wherein c(hcom) wt %≤c(sat) wt %, where c(sat) wt % is the saturation concentration of the heavy components in the polar solvent at the temperature of the first lean-solvent stream provided in step (A-2), expressed as weight percentage of the heavy components on the basis of the total weight of the heavy components and the polar solvent; preferably c(hcom) wt %<c(sat) wt %; preferably c(hcom) wt %≤0.8 c(sat) wt %; preferably c(hcom) wt %≤0.6 c(sat) wt %; preferably c(hcom) wt %≤0.5 c(sat) wt %. 
     
     
         3 . The process of  claim 1 , wherein step (A-3) further comprises (A-3b) contacting the first lean-solvent stream with a second cleansing bed comprising an ion exchange resin and/or alumina. 
     
     
         4 . The process of  claim 1 , wherein 0.01≤c(hcom)≤20; preferably 0.1≤c(hcom)≤15; preferably 0.5≤c(hcom)≤10; preferably 1≤c(hcom)≤5. 
     
     
         5 . The process of  claim 1 , wherein the activated carbon has a specific surface area from 1,000 to 1.500 m2/g, as measured using BET. 
     
     
         6 . The process of  claim 1 , wherein:
 the extraction column is an extractive distillation column or a liquid-liquid extraction column.   
     
     
         7 . The process of  claim 1 , wherein:
 the polar solvent is selected from tetraethylene glycol, triethylene glycol, diethylene glycol, ethylene glycol, methoxy triglycol ether, diglycolamine, dipropylene glycol, N-formyl morpholine, N-methyl pyrrolidone, 2,3,4,5-tetrahydrothiophene-1,1-dioxide (“sulfolane”), 3-methylsulfolane and dimethyl sulfoxide, tetramethylenesulfone, mixtures thereof, and/or admixtures with water thereof.   
     
     
         8 . The process of  claim 1 , wherein:
 the first lean-solvent stream has a temperature in a range from 25 to 80° C. when contacting the first cleansing bed; and/or   the first lean-solvent stream has a temperature in a range from 25 to 80° C. when contacting the second cleansing bed.   
     
     
         9 . The process of  claim 1 , further comprising:
 (A-5) feeding a second lean-solvent stream comprising the polar solvent into the extraction column;   wherein in a given time period, the first lean-solvent stream comprises the polar solvent at a total weight of W1, the second lean-solvent stream comprises the polar solvent at a total weight of W2, and 0.5%≤W1/(W1+W2)*100%≤10%; preferably 0.5%≤W1/(W1+W2)*100%≤8%; preferably 0.5%≤W1/(W1+W2)*100%≤5%; more preferably 1%≤W1/(W1+W2)*100%≤5%; still more preferably 1%≤W1/(W1+W2)*100%≤3%.   
     
     
         10 . The process of  claim 9 , wherein the first lean-solvent stream and the second lean-solvent stream are derived from a common lean-solvent stream. 
     
     
         11 . The process of  claim 1 , further comprising:
 (A-6) obtaining a bottoms stream from the extraction column, wherein the bottoms stream is rich in aromatic hydrocarbons and the polar solvent relative to the mixture feed;   (A-7) separating at least a portion of the bottoms stream in a solvent recovery column to obtain an upper stream rich in aromatic hydrocarbons and depleted in the polar solvent relative to the bottoms stream, and a third lean-solvent lower stream depleted in aromatic hydrocarbons relative to the bottoms stream; and   (A-8) deriving at least one of the first lean-solvent stream, the second lean-solvent stream, and the common lean-solvent stream from the third lean-solvent lower stream.   
     
     
         12 . The process of  claim 11 , further comprising:
 (A-9) deriving a fourth lean-solvent stream from the third lean-solvent stream;   (A-10) regenerating the fourth lean-solvent stream in a steam stripping regenerator and/or a vacuum regenerator to obtain a regenerated lean-solvent stream comprising steam and a bottoms heavy stream; and   (A-11) feeding the regenerated lean-solvent stream into one or both of the solvent recovery column and the extraction column.   
     
     
         13 . The process of  claim 1 , wherein the extraction column is a liquid/liquid extraction column, and the process does not include regenerating a portion of the polar solvent using a steam regenerator or a vacuum regenerator. 
     
     
         14 . The process of  claim 1 , further comprising:
 (A-12) interrupting or reducing supply of the mixture feed fed into the extraction column; and   (A-13) maintaining a temperature in the extraction column in proximity to temperature thereof before the interrupting or reducing supply of the mixture feed in step (A-12).   
     
     
         15 . A process for extracting aromatic hydrocarbons from a mixture feed comprising aromatic hydrocarbons and non-aromatic hydrocarbons, the process comprising:
 (B-1) feeding the mixture feed into an extractive distillation column;   (B-2) providing a first lean-solvent stream comprising a polar solvent at a concentration of c(ps) wt %, and heavy components at a total concentration of c(hcom) wt %, based on the total weight of the lean-solvent stream, where 75≤c(ps)≤99.99;   (B-3) obtaining a cleansed first lean-solvent stream by (B3-a) contacting the first lean-solvent stream with an primary cleansing bed comprising an ion exchange resin; and   (B-4) feeding at least a portion of the cleansed first lean-solvent stream into the extraction column.   
     
     
         16 . The process of  claim 15 , wherein c(hcom) wt %≤c(sat) wt %, where c(sat) wt % is the saturation concentration of the heavy components M the polar solvent at the temperature of the first lean-solvent stream provided in step (B-2), expressed as weight percentage of the heavy components on the basis of the total weight of the heavy components and the polar solvent; preferably c(hcom) wt %<c(sat) wt %; preferably c(hcom) wt %≤0.8 c(sat) wt %; preferably c(hcom) wt %≤0.6 c(sat) wt %; preferably c(hcom) wt %≤0.5 c(sat) wt %. 
     
     
         17 . The process of  claim 15 , wherein step (B-3) further comprises (B-3b) contacting the first lean-solvent stream with a secondary cleansing bed comprising activated carbon. 
     
     
         18 . The process of  claim 17 , wherein in step (B-3b), the primary cleansing bed comprises a basic ion exchange resin. 
     
     
         19 . The process of  claim 15 , wherein 0.01≤c(hcom)≤20; preferably 0.1≤c(hcom)≤15; preferably 0.5≤c(hcom)≤10; preferably 1 c(hcom)≤5. 
     
     
         20 . The process of  claim 15 , wherein the activated carbon has a specific surface area from 1,000 to 1,500 m2/g, as measured using BET. 
     
     
         21 . The process of  claim 15 , wherein:
 the first lean-solvent stream has a temperature in a range from 25 to 80° C. (preferably 25 to 65° C.) when contacting, the primary cleansing bed; and/or   the first lean-solvent stream has a temperature in a range from 25 to 80° C. (preferably 25 to 65° C.) when contacting the secondary cleansing bed.   
     
     
         22 . The process of  claim 15 , further comprising:
 (B-5) feeding a second lean-solvent stream comprising the polar solvent into the extraction column; wherein in a given time period, the first lean-solvent stream comprises the polar solvent at a total weight of W1, the second lean-solvent stream comprises the polar solvent at a total weight of W2, and 0.5%≤W1/(W1+W2)*100%≤10%; preferably 0.5%≤W1/(W1+W2)*100%≤8%, preferably 0.5%≤W1/(W1+W2)*100%≤5%, more preferably 1%≤W1/(W1+W2)*100%≤5%, still more preferably 1%≤W1/(W1+W2)*100%≤3%.   
     
     
         23 . The process of  claim 15 , further comprising:
 (B-6) obtaining a bottoms stream from the extraction column, wherein the bottoms stream is rich in aromatic hydrocarbons and the polar solvent relative to the mixture feed;   (B-7) separating at least a portion of the bottoms stream in a solvent recovery column to obtain an upper stream rich in aromatic hydrocarbons and depleted in the polar solvent relative to the bottoms stream, and a third lean-solvent lower stream depleted in aromatic hydrocarbons relative to the bottoms stream; and   (B-8) deriving at least one of the first lean-solvent stream, the second lean-solvent stream, and the common lean-solvent stream from the third lean-solvent stream.   
     
     
         24 . The process of  claim 23 , further comprising:
 (B-9) deriving a fourth lean-solvent stream from the third lean-solvent stream;   (B-10) regenerating the fourth lean-solvent stream in a steam stripping regenerator and/or a vacuum regenerator to obtain a regenerated lean-solvent stream comprising steam and a bottoms heavy stream; and   (B-11) feeding the regenerated lean-solvent stream into one or both of the solvent recovery column and the extraction column.   
     
     
         25 . The process of  claim 15 , further comprising:
 (B-12) interrupting or reducing supply of the mixture feed fed into the extraction column; and   (B-13) maintaining a temperature in the extraction column in proximity to temperature thereof before the interrupting or reducing supply of the mixture feed in step (A-12).