Method and apparatus for producing a needle coke with a mixed feedstock oil

Abstract

A method for producing a needle coke includes the following steps: (1) hydrotreating a mixture of a first feedstock oil and a second feedstock oil to obtain a hydrogenated product; (2) cracking the hydrogenated product to obtain a cracked product; and (3) producing the needle coke with the cracked product as a starting material. The first feedstock oil has an aromatic carbon ratio of greater than 65 mol %, the second feedstock oil has an aromatic carbon ratio of greater than 60 mol %, the first feedstock oil has a coking starting temperature lower than that of the second feedstock oil by 10-140° C. The apparatus for carrying out the method is also provided.

1 . A method for producing a needle coke, comprising the following steps:
 (1) hydrotreating a mixture of a first feedstock oil and a second feedstock oil to obtain a hydrogenated product;   (2) cracking the hydrogenated product to obtain a cracked product;   (3) producing the needle coke with the cracked product as a starting material,   wherein the first feedstock oil has an aromatic carbon ratio of greater than 65 mol % (preferably 70 mol %-95 mol %), the second feedstock oil has an aromatic carbon ratio of greater than 60 mol % (preferably 70 mol %-90 mol %), and the first feedstock oil has a coking starting temperature lower than that of the second feedstock oil by 10-140° C., preferably by 35-105° C.   
     
     
         2 . The method according to  claim 1 , wherein the weight ratio of said second feedstock oil to said first feedstock oil is 1:1-1:0.001 (preferably 1:0.2-1:0.01). 
     
     
         3 . The method according to  claim 1 , wherein said first feedstock oil has a coking starting temperature of 350° C.-420° C., preferably 380° C.-415° C., said second feedstock oil has a coking starting temperature of 430° C.-490° C., preferably 450° C.-485° C. 
     
     
         4 . The method according to  claim 1 , wherein said second feedstock oil is a catalytic slurry oil, said first feedstock oil is an ethylene tar extract. 
     
     
         5 . The method according to  claim 1 , wherein said second feedstock oil has an ash content of not higher than 0.01 wt %, preferably not higher than 0.005 wt %, and a sulfur content of higher than 0.5 wt %, preferably 0.8 wt %-1.5 wt %, and said first feedstock oil has an ash content of not higher than 0.01 wt %, preferably not higher than 0.005 wt %, and a sulfur content of not higher than 0.1 wt %, preferably not higher than 0.03 wt %. 
     
     
         6 . The method according to  claim 1 , wherein said first feedstock oil is prepared according to the following steps:
 (i) extracting an ethylene tar with a solvent to obtain an extract phase and a raffinate phase;   (ii) removing the solvent from the extract phase to obtain an aromatics-enriched oil, and then separating said aromatics-enriched oil to obtain a first lighter oil and said first feedstock oil (i.e. a first heavier oil).   
     
     
         7 . The method according to  claim 6 , wherein said solvent is selected from C3-C12 normal alkanes or cycloalkanes, preferably from C5-C12 normal alkanes, and/or, the mass ratio of said ethylene tar to said solvent is 1:0.5-1:5, preferably 1:1-1:2. 
     
     
         8 . The method according to  claim 6 , wherein said extraction is performed at a temperature of 30° C.-110° C., preferably 40° C.-80° C. 
     
     
         9 . The method according to  claim 6 , wherein said first heavier oil has a 5% distillation temperature of 300° C.-400° C., preferably 340° C.-380° C. 
     
     
         10 . The method according to  claim 6 , wherein said first lighter oil has a 95% distillation temperature of 280° C.-400° C. (preferably 335° C.-380° C.), and/or, said first lighter oil is subjected to a condensation reaction to produce a condensation product, then said condensation product is used to produce a petroleum coke. 
     
     
         11 . The method according to  claim 10 , wherein the operation conditions of the condensation reaction comprise: a reaction temperature of 350° C.-530° C., preferably 380° C.-450° C., a reaction pressure of 0.01 MPa-5 MPa, preferably 1 MPa-3 MPa, a residual time of 0.1 h-15 h, preferably 0.5 h-6 h. 
     
     
         12 . The method according to  claim 1 , wherein before the cracking, the hydrogenated product is separated to obtain a lighter component (such as gas, naphtha) and a hydrogenated tail oil, and then the hydrogenated tail oil is cracked to obtain the cracked product. 
     
     
         13 . The method according to  claim 1 , wherein the operation conditions for said hydrotreating comprise: a reaction temperature of 310° C.-450° C., preferably 340° C.-390° C., a reaction pressure of 2 MPa-20 MPa, preferably 4 MPa-8 MPa, a hydrogen/oil volume ratio of 100-2500, preferably 800-1800, an LHSV by volume of 0.1 h −1 -2.0 h −1 , preferably 0.6 h −1 -1.2 h −1 . 
     
     
         14 . The method according to  claim 12 , wherein said hydrogenated tail oil has a 5% distillation temperature of 160° C.-250° C., preferably 180° C.-210° C., and/or, said hydrogenated tail oil has a sulfur content of not higher than 0.4 wt % (preferably not higher than 0.35 wt %). 
     
     
         15 . The method according to  claim 1 , wherein before being used to produce the needle coke, said cracked product is separated to produce a second lighter oil, an intermediate distillate oil and a second heavier oil, and then said intermediate distillate oil is used as a starting material to produce the needle coke. 
     
     
         16 . The method according to  claim 15 , wherein the operation conditions of said cracking include: a reaction temperature of 380° C.-520° C., preferably 420° C.-490° C., a reaction pressure of 0.1 MPa-5 MPa, preferably 0.2 MPa-1.0 MPa, a residual time of 0.01 h-30 h, preferably 0.1 h-3 h, an oil-to-steam mass ratio of 100:0.1-100:20, preferably 100:1-100:8. 
     
     
         17 . The method according to  claim 15 , wherein said intermediate distillate oil has a distillation range of 330° C.-530° C. (preferably 350° C.-500° C.). 
     
     
         18 . The method according to  claim 15 , wherein said second lighter oil has a 95% distillation temperature of 300° C.-400° C. (preferably 320° C.-380° C.), said second heavier oil has a 5% distillation temperature of 460° C.-550° C. (preferably 485° C.-510° C.). 
     
     
         19 . The method according to  claim 15 , wherein at least a part of said second lighter oil is recycled back to said hydrotreating; or at least a part of said second lighter oil is subjected to a condensation reaction to produce a condensation product, then said condensation product is used to produce a petroleum coke; or a part of said second lighter oil is recycled back to said hydrotreating, and the other part is subjected to the condensation reaction. 
     
     
         20 . The method according to  claim 6 , wherein said raffinate phase and said second heavier oil are mixed, and then the resulting mixture is used to produce a petroleum coke, and/or, the mass ratio of said raffinate phase to said second heavier oil is 1:1-0.01:1 (preferably 0.5:1-0.1:1). 
     
     
         21 . The method according to  claim 10 , wherein the operation conditions for producing the petroleum coke comprise: a heating furnace outlet temperature of 440° C.-550° C., preferably 490° C.-510° C., a coke drum top pressure of 0.01 MPa-2.5 MPa, preferably 0.1 MPa-0.5 MPa, and a reaction duration of 10 h-48 h, preferably 18 h-30 h. 
     
     
         22 . The method according to  claim 1 , wherein the operation conditions for producing said needle coke: a heating furnace outlet temperature of 420° C.-560° C., preferably 440° C.-530° C., a coke drum top pressure of 0.01 MPa-2.5 MPa, preferably 0.2 MPa-1.3 MPa, and a reaction duration of 10 h-72 h, preferably 32 h-54 h. 
     
     
         23 . An apparatus for producing a needle coke, comprises the following units:
 a feedstock oil supplying unit, which is configured for providing a first feedstock oil and a second feedstock oil;   a hydrogenation unit, which is configured for hydrotreating a mixture of the first feedstock oil and the second feedstock oil, to obtain a hydrogenated product;   a cracking unit, which is configured for cracking the hydrogenated product to obtain a cracked product;   a needle coke production unit, which is configured for producing the needle coke with the cracked product as a starting material,   wherein the first feedstock oil has an aromatic carbon ratio of greater than 65 mol % (preferably 70 mol %-95 mol %), the second feedstock oil has an aromatic carbon ratio of greater than 60 mol % (preferably 70 mol %-90 mol %), and the first feedstock oil has a coking starting temperature lower than that of the second feedstock oil by 10-140° C., preferably by 35-105° C.   
     
     
         24 . The apparatus according to  claim 23 , comprises the following units:
 an extraction unit, which is configured for receiving an ethylene tar and a solvent and then treating same to produce an extract phase and a raffinate phase;   a solvent recovery unit, which is configured for receiving the extract phase from the extraction unit, and then separating same to produce a regenerated solvent and an aromatics-enriched oil;   a first separation unit, which is configured for receiving the aromatics-enriched oil from the solvent recovery unit, and then cutting same to produce a first lighter oil and a first heavier oil (corresponding to said first feedstock oil);   a hydrogenation reaction unit, which is configured for receiving said first feedstock oil and a catalytic slurry oil (corresponding to said second feedstock oil), and then subjecting same to a hydrogenation reaction in the presence of hydrogen gas and a hydrogenation catalyst;   a hydrogenation separation unit, which is configured for receiving a hydrogenated product from the hydrogenation reaction unit, and then separating same to produce gas, naphtha, and a hydrogenated tail oil;   a cracking reaction unit, which is configured for receiving the hydrogenated tail oil from the hydrogenation separation unit, and then subjecting same to a cracking reaction in the presence of a carrier gas,   a second separation unit, which is configured for receiving a cracked product from the cracking reaction unit, and then separating same to produce a second lighter oil, an intermediate distillate oil and a second heavier oil; and   a needle coke production unit, which is configured for receiving said intermediate distillate oil, and then subjecting same to a reaction to produce the needle coke.