US 2007/0181462 A2Published application

A process for the production of needle coke

AssigneeIndian Oil Corporation Limited

InventorsDebasis Bhattacharyya, Satheesh Kumaran, Bandaru Prasad Gupta, Pramod Kumar, Asit Das, Gadari Saidulu, Satyen Das, Gurpreet Kapur, Veena Bansal, Venkatachalam Krishnan, Satish Makhija, Sobhan Ghosh, Niranjan Raje

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Abstract

A process is disclosed for producing needle coke from heavy atmospheric distillation residues having sulfur no more than 0.7 wt %, which process involves the steps of heating the feedstock to a temperature in the range of 440 to 520° C. for thermal cracking in a soaking column under pressure in the range of 1 to 10 kg/cm2 to separate the easily cokable material, separating the cracked products in a quench column and a distillation column and then subjecting the hydrocarbon fraction from the bottom of the quench column and a hydrocarbon fraction having a boiling point in the range of 380 to 480° C. from the distillation column and/or any other suitable heavier hydrocarbon streams in a definite ratio depending on certain characteristic parameters to thermal cracking in a second soaking column at a temperature of 460 to 540° C., pressure in the range of 2 to 20 kg/cm2 in presence of added quantity of steam for formation of a mesophase carbonaceous structure which on steam stripping and cooling forms a solid crystalline coke suitable for manufacturing of graphite electrode of large diameter having co-efficient of thermal expansion lower than 1.1×10−6/° C. measured on graphite artifact in the temperature range of 25 to 525° C.

Claims16

Dependent claims

A process for preparing crystalline or semi-crystalline petroleum coke having needle like structure suitable for manufacturing high temperature graphite electrodes from atmospheric residue obtained from bottom of atmospheric crude distillation column, said process comprising the steps:

(a) preheating the atmospheric residue to a temperature in the range of 440° to 520° C.;
(b) carrying out a first thermal cracking of the heated atmospheric residue obtained in step (a) and subjecting the cracked hydrocarbon product to a first delayed coking step in a first coking column to form cracked hydrocarbon vapors and easily cokable material and separating the easily cokable material from the cracked hydrocarbon vapors as solid coke;
(c) adding quench stream to the cracked hydrocarbon vapors obtained in step (b) in a quench column to obtain a condensate containing heavier hydrocarbon fraction and vapors containing lighter hydrocarbon fractions;
(d) separating the vapor containing lighter hydrocarbon fractions into at least a gas component and a hydrocarbon fraction having true boiling point in the range of 380° C.-480° C. in a distillation column;
(e) mixing the condensate obtained in the step (c), the hydrocarbon fraction having boiling point in the range of 380-480° C. thus obtained in step (d) and optionally clarified oil (CLO) obtained from FCC process and/or thermal tars and/or aromatic extract and heating the mixture in a pre-heater to a temperature in the range of 460 to 540° C., and
(f) passing steam through the heated mixture of step (e) for carrying out a second thermal cracking and subjecting the cracked hydrocarbon product thus obtained to a second delayed coking step in a second coking column thereby obtaining crystalline petroleum coke having needle structure and a cracked hydrocarbon product mixture and separating the crystalline petroleum coke having needle structures.

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Dependencies are inferred from the claim text.