RU2560441C1 - Method of decelerated coking of oil residues - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention can be used in the oil industry. The method of decelerated coking of oil residues includes the treatment of a raw material for coking by mixing the input raw tar with heave gasoil of catalytic cracking with further heating of the raw mixture up to 280-320°C. The produced raw mixture is enriched at the bottom of the rectification tower with a recycle of heavy coker gasoil in the quantity of at least 40%. Downstream the rectification tower the produced raw mixture is mixed with light coker gasoil taken in the quantity of at least 10% of the input raw material, heated again up to coking distillates to the rectification tower.

EFFECT: invention allows an increase in run between repairs of the furnace, reduction in silicon content in the oil coke and power consumption.

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Description

The invention relates to methods for delayed coking of oil residues and can be used in the refining industry.

A known method of delayed coking to obtain low-sulfur petroleum coke, including aromatization of the feedstock - tar by mixing it with heavy catalytic cracking gas oil (THC), or heavy coking gas oil recycle (THC), or pyrolysis resin, or a mixture thereof in an amount of 4-15% on raw materials and further delayed coking of the obtained raw materials (Pat. RF №2206595, IPC 7 С10В 55/00, publ. 06/20/2003).

The disadvantage of this method is the low yield of coke to the coking feedstock.

The closest to the proposed method in terms of technical nature and the achieved result is a method for delayed coking of oil residues, including the preparation of coking raw materials by mixing the feedstock mixture of tar and visbreaking residue first with heavy catalytic cracking gas oil (THC), taken in an amount of at least 30% feedstock, followed by primary heating of the resulting feedstock to 280-320 ° C and enrichment at the bottom of the distillation column with heavy coking gas oil (THC) recycle in the amount of n less than 30%, the secondary raw material mixture obtained by heating to carbonization temperature, carbonization reactor with the output coker fractionator in the distillate products (Pat. Russian №2469067, IPC S10V 55/00, publ. 10.12.2012).

The disadvantage of this method is the significant involvement of heavy catalytic cracking gas oil and visbreaking residue in the coking feed, which leads to a deterioration in the quality of the obtained petroleum coke due to an increase in silicon therein. As well as mechanical impurities (catalyst dust) contained in the heavy gas oil of catalytic cracking, which are involved in coking feeds, lead to premature wear and clogging of equipment (heat exchangers, mass transfer devices and furnaces) and, as a result, to reduce the overhaul distance of the installation. In addition, the use of visbreaking residue in the coking feedstock also leads to a decrease in the overhaul run of furnaces.

The present invention is aimed at improving the quality of petroleum coke and increasing the overhaul mileage of the installation.

This is achieved by the fact that in the method of delayed coking of oil residues, including the preparation of coking feedstock by mixing the feedstock with heavy gas oil of catalytic cracking and heating the resulting feed mixture to 280-320 ° C, subsequent enrichment of the feed mixture at the bottom of the distillation column with recirculating heavy coking gas oil, secondary heating the resulting raw material mixture to a coking temperature and coking in a reactor with the output of distillate coking products into a distillation column according to the invention eniyu the resulting raw material mixture introduced into the rectification column at least 10% of light coker gas oil to the feedstock, wherein the amount of heavy coker gas oil recirculate the bottom of the rectification column is at least 40%.

The introduction of light coking gas oil into the feed mixture after a distillation column will reduce the amount of heavy catalytic cracking gas oil introduced into the coking feedstock and, therefore, reduce the content of mechanical impurities (silicon) in the resulting petroleum coke, while maintaining the overhaul range of the furnace.

An increase in the amount of heavy coking gas oil recirculate at the bottom of the distillation column up to 40% or more will allow maintaining the coke yield on the feedstock.

The method is as follows.

10-15% heavy gas oil of catalytic cracking is added to the coking feedstock - tar, the feedstock is then preheated in heat exchangers and in a convection oven to a temperature of 280-320 ° C and fed down to the distillation column, where it is as a result contact with the coking vapors coming from a working reactor with a temperature of 390-400 ° C, is heated to a temperature of 340-360 ° C, enriched with heavy fractions - recirculation of heavy coking gas oil in an amount of 40-50% for obtained with raw mix. The amount of recirculation of heavy coking gas oil introduced into the raw material mixture at the bottom of the distillation column is controlled by varying the temperature of the coking vapors entering the bottom of the distillation column from a working reactor, or by changing the place of introduction of the raw mixture into it. Light coking gas oil in the amount of 10-15% is added to the newly obtained raw material mixture — secondary raw materials, and the obtained raw material mixture is fed to the furnace for heating to the coking temperature of 485-505 ° C, and then to the coking reactor.

The following are specific examples of the implementation of the proposed method.

In the experiments, products with the following quality indicators were used:

- tar: density 994 kg / m ³ , coking ability 13.8%, sulfur content 0.92%, silicon content 30 ppm;

- natural recycle - heavy coking gas oil (THC): density 963 kg / m ³ , coking ability 0.55%;

- heavy catalytic cracking gas oil (THCK): density 1036 kg / m ³ , coking ability 3.46%;

- light coking gas oil (LTC): density 780 kg / m ³ .

The proposed method is illustrated by the following examples, which are given in the table. These tables were obtained experimentally on pilot coking units (cube) and thermal cracking (flowing) at a pressure of 0.1 MPa and a temperature of 495 ° C at the outlet of the furnace.

Table The performance of the method of delayed coking The composition of the raw materials and indicators of the delayed coking process Examples The composition of the coking feed The output of coke for feedstock,% Silicon content in coke, ppm Time to coking of the furnace coil, min Feedstock,% Diluent THCK,% of feedstock LGA,% of feedstock Recycle - THC,% Example 1 Tar-100 25 - thirty 27.0 340 fifteen Example 2 Tar-100 fifteen 10 40 27.0 300 twenty Example 3 Tar-100 10 fifteen fifty 27.0 260 25

The table shows that a decrease in the amount of diluent - heavy gas oil of catalytic cracking up to 10-15% for coking feedstock with a simultaneous increase in the number of heavy gas oil recirculates involved in the feed mixture up to 40-50% and the addition of light coking gas oil in the resulting raw material mixture in an amount of 10 -15% on the feedstock allows to reduce the silicon content in coke and increase the overhaul mileage of the furnace, while maintaining the yield of petroleum coke.

Thus, the proposed method allows to improve the quality of petroleum coke by reducing the silicon content in it - a limited indicator when producing coke for the aluminum industry (the lower its content in coke, the higher the category of its quality), and to increase the overhaul mileage of the furnace, while maintaining this is his exit to the feedstock.

Claims (1)

A method for delayed coking of oil residues, including the preparation of coking feedstock by mixing the feedstock with heavy gas oil of catalytic cracking, followed by primary heating of the obtained feedstock to 280-320 ° C and subsequent enrichment of the feed mixture at the bottom of the distillation column with recirculation of heavy coking gas oil, secondary heating of the obtained feed mixture to coking temperature and coking in the reactor with the output of distillate coking products in a distillation column, characterized in that in the floor after the distillation column, at least 10% of light coking gas oil is introduced into the feedstock, and the amount of heavy coking gas oil recycle at the bottom of the distillation column is at least 40%.