Process for production of anisotropic coke

Patent metadata

Field	Value
Publication number	US-10934494-B2
Application number	US-202016777031-A
Country	US
Kind code	B2
Filing date	Jan 30, 2020
Priority date	Apr 9, 2019
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

The present invention relates to a process for production of anisotropic coke from a hydrocarbon feedstock and a system for producing the same. More particularly, the present invention relates to a thermal cracking of heavy petroleum residue producing petroleum coke and lighter hydrocarbon products. The invented process utilizes a novel scheme for production of a premium quality coke from primarily, a clarified oil feedstock. Clarified oil from fluid catalytic cracking unit is routed through a process scheme comprising a separator column, hydrotreatment section and an aromatic extraction section to create an ad-mix of effluents which form the feedstock to a thermal cracking unit. Premium quality anisotropic coke is produced in the thermal cracker reactor drums under tailor made process conditions employing the said feedstock.

First claim

The invention claimed is:

1. A process for production of anisotropic coke from a hydrocarbon feedstock comprising:
(i) routing a first fraction of the hydrocarbon feedstock to a separator column and a second fraction of the hydrocarbon feedstock to an aromatic extractor unit;
(ii) separating the first fraction of the hydrocarbon feedstock in the separator column, in to a lighter material and a first heavy material;
(iii) desulfurizing the first heavy material in a hydrotreater reactor to obtain a second heavy material;
(iv) aromatic extracting the second fraction of the hydrocarbon feedstock in the aromatic extractor unit parallel to the separator column with a solvent to obtain an aromatic extract stream and a paraffinic raffinate stream;
(v) sending a combined feedstock comprising the lighter material, the second heavy material and the aromatic extract stream to a main fractionator column of a thermal cracker unit to obtain a secondary feedstock; and
(vi) heating the secondary feedstock in a furnace to obtain a hot secondary feedstock and thermally cracking the hot secondary feedstock in coke drums for producing the anisotropic coke and lighter hydrocarbon product.

2. The process as claimed in claim 1 , wherein the desulfurization comprises:
(a) heating the first heavy material in a furnace section along with a recycle hydrogen stream from a compressor to obtain a hot feed stream;
(b) desulfurizing the hot feed stream in the hydrotreater reactor for generating a desulfurized fraction; and
(c) routing the desulfurized fraction to a high pressure separator to separate a hydrogen gas from the desulfurized fraction and then to a low pressure separator to separate other gaseous product and the second heavy material.

3. The process as claimed in claim 1 , wherein the aromatic extraction comprises:
a. extracting the second part of the feedstock in the aromatic extractor with the solvent coming from solvent recovery sections to obtain the paraffinic raffinate stream and an initial aromatic extract stream;
b. sending the paraffinic raffinate stream to a first solvent recovery section to separate the solvent and to obtain a paraffinic raffinate and routing the paraffinic raffinate to other secondary processing units for further conversion; and
c. sending the initial aromatic extract stream to a second solvent recovery section to separate the solvent and to obtain the aromatic extract stream.

4. The process as claimed in claim 1 , wherein the thermal cracking comprises:
(a) heating the secondary feedstock in a heat furnace to obtain a hot secondary feedstock;
(b) thermal cracking the hot secondary feedstock in one of coking drums, which is in feed processing mode by providing an extended residence time to allow completion of coking reactions to obtain a product vapor and anisotropic coke;
(c) routing the product vapor to the main fractionator column to obtain gaseous products, naphtha, kerosene, light gas oil, heavy gas oil and fuel oil component; and
(d) removing the anisotropic coke by a decoking operation.

5. The process as claimed in claim 1 , wherein a weight ratio of the hydrocarbon feedstock is split into two fractions routed to the separator column and the aromatic extractor unit is in the range of 0.1 to 10.

6. The process as claimed in claim 1 , wherein the hydrocarbon feedstock is selected from the group consisting of clarified oil or slurry oil from fluid catalytic cracking unit, reduced fuel oil (RFO) from the bottom of delayed coker quench column, coker fuel oil, reduced crude oil, vacuum residue, vacuum gasoil, aromatic extracts, thermal tar, ethylene tar, unconverted oil from hydrocracker unit and a blend thereof.

7. The process as claimed in claim 1 , wherein the separator column operates at a pressure of 0.1 to 3 Kg/cm 2 (g) with a bottom temperature in the range of 350 to 380° C.

8. The process as claimed in claim 1 , wherein the hydrotreater reactor operates at a temperature ranging from 330 to 380° C. and pressure ranging from 40 to 50 Bar.

9. The process as claimed in claim 1 , wherein the aromatic extractor unit is operated at a temperature ranging from 30 to 150° C. with the solvent/hydrocarbon feedstock weight ratio ranging from 1:1 to 3:1 (wt/wt).

10. The process as claimed in claim 1 , wherein the solvent is selected from the group consisting of N-methyl pyrrolidone (NMP), diethylene glycol, sulpholane, dimethyl sulfoxide, monomethyl formamide, tetraethylene glycol and furfural.

11. The process as claimed in claim 1 , wherein the thermal cracker unit producing the anisotropic coke is operated at a temperature ranging from 470 to 510° C., pressure ranging from 0.5 to 15 Kg/cm 2 (g) and residence time ranging from 10 to 30 hrs.

12. A system for production of anisotropic coke from a hydrocarbon feedstock comprising:
(i) a separator column to receive a first fraction of the hydrocarbon feedstock and separating it in to a lighter material and first heavy material;
(ii) an aromatic extractor unit parallel to the separator column for extracting a second fraction of the hydrocarbon feedstock with a solvent to obtain an aromatic extract stream;
(iii) a hydrotreater reactor in connection with the separator column for desulfurizing the first heavy material to obtain a second heavy material; and
(iv) a thermal cracker unit having a main fractionator column, furnace and coke drums for thermally cracking a combined feedstock consisting of the lighter material, aromatic extract stream and the second heavy material for producing the anisotropic coke and lighter hydrocarbon product.

13. The system as claimed in claim 12 , wherein the system comprises:
(a) a furnace section in connection and prior to the hydrotreater reactor for heating the first heavy material along with a recycle hydrogen stream to obtain a hot feed stream;
(b) a compressor in connection with the furnace section for providing the recycle hydrogen stream;
(c) the hydrotreater reactor for desulfurizing the hot feed stream for generating a desulfurized fraction; and
(d) a high pressure separator for separating the desulfurized fraction into a hydrogen gas and a low pressure separator to separate other gaseous product and the second heavy material.

14. The system as claimed in claim 12 , wherein the system comprises:
a. the aromatic extractor unit parallel to the separator column for extracting the second part of the feedstock with the solvent streams to obtain a paraffinic raffinate stream and an initial aromatic extract stream;
b. a first solvent recovery section to receive the paraffinic raffinate stream and to separate the solvent to obtain a paraffinic raffinate and recovered solvent; and
c. a second solvent recovery section to receive the initial aromatic extract stream and to separate the solvent and to obtain the aromatic extract stream.

15. The system as claimed in claim 12 , wherein the system comprises:
a. the main fractionator column which receives a combined feed stream from the separator column, aromatic extraction section and hydrotreatment section to prepare a secondary feedstock and also for fractionating the product vapor from coke drums to obtain a gaseous product, kerosene, light gas oil, heavy gas oil and fuel oil component;
b. a furnace for heating the secondary feedstock from the main fractionator column and to obtain a hot secondary feedstock; and
c. coking drums for coking through thermal cracking of the hot secondary feedstock in feed processing mode by providing an extended residence time to allow completion of coking reactions to obtain a product vapor and the anisotropic coke.

Assignees

• Indian Oil Corp Ltd

Inventors

• Prasad Terapalli Hari Venkata Devi
• Pradeep Ponoly Ramachandran
• Das Satyen Kumar
• Kumar Kamal
• Karumanchi Ramesh
• Sau Madhusudan
• Bhattacharyya Debasis
• Mazumdar Sanjiv Kumar
• RAMAKUMAR Sankara Sri Venkata

Classifications

• B01J19/245

  placed in series · CPC title

• C10G69/06 Primary

  including at least one step of thermal cracking in the absence of hydrogen · CPC title

• C10B57/045 Primary

  containing mineral oils, bitumen, tar or the like or mixtures thereof · CPC title

• C10G55/04

  including at least one thermal cracking step · CPC title

• B01J2219/0004

  Processes in series · CPC title