Process for synergistic co-conversion of used oils to value added products

Abstract

Used Lubricating Oil (ULO) and Used Cooking Oil (UCO) are waste oils generated from Automotive Machines/Heavy Machinery, and Cooking/Frying respectively. These oils, unless recycled or refined using conventional methods, can no longer be used for their respective purposes. The present disclosure provides a process wherein synergistic co-conversion of ULO and UCO is done in a reactor vessel to reduce the impurity content of the ULO+UCO mixture and co-processing the heavier fraction of ULO+UCO mixture with residue feedstock in Delayed Coker Unit (DCU) to produce value added products while utilizing the lighter cut of ULO+UCO mixture in steam cracker to produce olefins and aromatics.

We claim: 
     
         1 . A process for synergistic co-conversion of used oils to value added products, the process comprising:
 (i) mixing a Used Lubricating Oil (ULO) comprising metal and phosphorus impurities with a Used Cooking Oil (UCO) comprising acid impurities in a reactor, wherein the ULO is reacted with the UCO to produce a reaction mixture;   (ii) fractionating the reaction mixture in a pre-fractionator column into a lighter fraction and a heavier fraction;   (iii) sending the lighter fraction and a straight run naphtha stream from Atmospheric Distillation Unit (ADU) to a hydrotreating unit to obtain a low sulfur stream;   (iv) routing the low sulfur stream to a steam cracker unit to produce high value petrochemicals;   (v) mixing the heavier fraction and a residue feed in a surge drum to obtain a feed mixture, and pumping the feed mixture using a surge drum pump as a primary feed stream to a bottom of a main fractionator (MF);   (vi) mixing the primary feed stream with an internal recycle in the main fractionator to obtain a secondary feed stream and pumping the secondary feed stream using a fractionator bottom pump through a coker furnace;   (vii) heating the secondary feed stream inside the coker furnace to obtain a coker furnace effluent; and   (viii) thermally cracking the coker furnace effluent inside a plurality of coke drums to obtain a coke drum effluent and routing the coke drum effluent to the main fractionator for fractionating a product and solid petroleum coke, wherein the solid petroleum coke is removed after completion of a coking cycle.   
     
     
         2 . The process as claimed in  claim 1 , wherein the ULO and the UCO are mixed in a ratio ranging from 0.1 to 10 by weight. 
     
     
         3 . The process as claimed in  claim 1 , wherein the lighter fraction of the reaction mixture has lower phosphorus, calcium and zinc compared to the ULO. 
     
     
         4 . The process as claimed in  claim 1 , wherein the reactor is operated at a temperature in a range of 25-200° C., at a pressure in a range of 1-5 bar and at a residence time in a range of 5-120 minutes. 
     
     
         5 . The process as claimed in  claim 1 , wherein the reactor is a continuous stirred tank reactor, a plug flow reactor, a batch reactor or a fluidized bed reactor. 
     
     
         6 . The process as claimed in  claim 1 , wherein the reaction mixture has a lower Total Acid Number (TAN) compared to the mixture of ULO and UCO. 
     
     
         7 . The process as claimed in  claim 1 , wherein the lighter fraction has a boiling point below 200° C., and the heavier fraction has a boiling point above 200° C. 
     
     
         8 . The process as claimed in  claim 1 , wherein the steam cracker unit is operated at a temperature in a range of 750-950° C., at a pressure in a range of 0.5-2.0 bar, at a residence time in a range of 0.1-1.0 seconds, and wherein the steam to the low sulfur stream ratio is in a range of 0.2-1.4. 
     
     
         9 . The process as claimed in  claim 1 , wherein the plurality of coke drums is operated at a temperature in a range of 460-520° C., at a pressure in a range of 1-5 bar, and at the coking cycle of 10-36 hours. 
     
     
         10 . The process as claimed in  claim 1 , wherein the plurality of coke drums is operated in parallel to complete the coking cycle one after another, and the coke drum effluents is systematically passed into each of the plurality of coke drums through a switch valve to facilitate the coking cycle in each of the plurality of coke drums. 
     
     
         11 . A process for synergistic co-conversion of used oils to value added products, the process comprising:
 (i) fractionating a Used Lubricating Oil (ULO) comprising metal and phosphorus impurities in a pre-fractionator column into a lighter fraction and a heavier fraction;   (ii) subjecting the lighter fraction and a straight run naphtha stream from Atmospheric Distillation Unit (ADU) to a hydrotreating unit to obtain a low sulfur stream;   (iii) routing the low sulfur stream to a steam cracker unit to produce high value petrochemicals;   (iv) reacting the heavier fraction with Used Cooking Oil (UCO) comprising acid impurities in a reactor to produce a reaction mixture;   (v) sending the reaction mixture and a residue feed to a surge drum to obtain a feed mixture, and pumping the feed mixture using a surge drum pump as a primary feed stream to a bottom of a main fractionator;   (vi) mixing the primary feed stream with an internal recycle in the main fractionator to obtain a secondary feed stream and pumping the secondary feed stream using a fractionator bottom pump through a coker furnace;   (vii) heating the secondary feed stream inside the coker furnac to obtain a coker furnace effluent; and   (viii) thermally cracking the coker furnace effluent inside a plurality of coke drums to obtain a coke drum effluent and routing the coke drum effluent to the main fractionator for fractionating a product and solid petroleum coke, wherein the solid petroleum coke is removed after completion of a coking cycle.   
     
     
         12 . The process as claimed in  claim 11 , wherein the heavier fraction of ULO and the UCO are mixed in a ratio ranging from 0.1 to 10 by weight. 
     
     
         13 . The process as claimed in  claim 11 , wherein the reactor is operated at a temperature in a range of 25-200° C., at a pressure in a range of 1-5 bar and at a residence time in a range of 5-120 minutes. 
     
     
         14 . The process as claimed in  claim 11 , wherein the reactor is a continuous stirred tank reactor, a plug flow reactor, a batch reactor or a fluidized bed reactor. 
     
     
         15 . The process as claimed in  claim 11 , wherein the steam cracker unit is operated at a temperature in a range of 750-950° C., at a pressure in a range of 0.5-2.0 bar, at a residence time in a range of 0.1-1.0 seconds, and wherein the steam to the low sulfur stream ratio is in a range of 0.2-1.4. 
     
     
         16 . The process as claimed in  claim 11 , wherein the plurality of coke drums is operated at a temperature in a range of 460-520° C., at a pressure in a range of 1-5 bar, and at the coking cycle of 10-36 hours. 
     
     
         17 . The process as claimed in  claim 11 , wherein the plurality of coke drums is operated in parallel to complete the coking cycle one after another, and the coke drum effluents is systematically passed into each of the plurality of coke drums through a switch valve to facilitate the coking cycle in each of the plurality of coke drums. 
     
     
         18 . The process as claimed in  claim 11 , further comprising fractionating the ULO into a middle fraction. 
     
     
         19 . The process as claimed in  claim 18 , wherein the lighter fraction has a boiling point below 200° C., the middle fraction has a boiling point in a range of 200-370° C., and the heavier fraction has a boiling point above 370° C. 
     
     
         20 . The process as claimed in  claim 18 , wherein the middle fraction is used as a quenching stream for quenching the coke drum effluent.