RU2786225C1 - Petroleum needle coke plant - Google Patents

Abstract

FIELD: oil refining.

SUBSTANCE: invention relates to the field of oil refining, in particular to a plant for the production of petroleum needle coke. The proposed plant includes a feedstock heating furnace, a light feedstock evaporator, heat exchange equipment, a light feedstock separator, a thermocondensation reactor, a distillation column, a secondary feedstock heating furnace, and coking chambers. In the unit, the feedstock feed line is sent through the feedstock heating furnace to the evaporator, where the feedstock is separated into light and heavy streams, while the heavy stream is sent to the distillation column through the feedstock heating furnace, and the light component, mixing with recirculating middle distillates from the distillation column after the removal of the gas fraction in the light feedstock separator, it is sent through the feedstock heating furnace to the thermal condensation reactor. In the thermal condensation reactor, it is maintained at a temperature of 500-570°C and a pressure of 0.9 to 2.5 MPa, after which it is sent to a distillation column, from the cube of which the secondary raw material is sent for coking through the secondary raw material heating furnace to the coke chambers, which operate in turn. Wherein, coking gas oil is returned to the distillation column, from which gasoline fraction vapors and gaseous products are removed, and middle distillates are sent for recycling.

EFFECT: creation of a simplified installation for the production of needle coke.

7 cl, 1 dwg

Description

The invention relates to the field of oil refining, in particular, to a method for producing highly anisotropic petroleum needle coke by delayed coking. The invention can be used for the preparation of raw materials and the subsequent production of needle (anisotropic) coke, for the production of graphite products (steel-smelting electrodes, etc.).

Needle coke is a high-margin and much more environmentally friendly product compared to other types of petroleum coke. Anisotropic (needle) coke has a pronounced orderly directed fiber structure, is characterized by a low content of heteroimpurities (sulfur, nitrogen, metals), high specific density and good graphitization (the ability to take on a crystalline, layered structure of graphite at high temperatures of about 3000°C). Needle coke is a demanded raw material for the production of graphite products operated under harsh conditions of 3000°C or more (electrodes for metallurgy, structural materials, etc.).

From the prior art there are many solutions aimed at obtaining petroleum coke, in particular needle coke.

An established technological solution is the use of distillation columns to ensure the formation of raw materials for subsequent coking from the heaviest fractions. Along with this, traditionally in the technological process, heating of raw materials is practiced before being fed to coking. In confirmation of this, we can consider the technological scheme known from the prior art [Reference. Processes of oil refining. Supplement to the journal "Oil and Gas Technologies / Oil and Gas Technologies, No. 2 February 2009 / M: Fuel and Energy / 2009 / 108 s], in which the raw material is fed directly into the distillation column, where it is combined with the recirculating coking product, and then it is sent with preheating for coking. Or a more complex variation of the technology, close to real production conditions, replicated by ABB Lummus Global [Malik Ram, Gary and Hamilton, "Delayed coker design considerations and project execution", NPRA 2002 Annual Meeting, March 17-19, 2002], where raw materials, heated in the heat exchanger enters the bottom of the distillation column, where it mixes with the condensed recirculation product. The mixture is pumped through the oven, in which it is heated to a predetermined temperature, and sent for coking.

A known method for producing petroleum coke [RU 2209826, published 10.08.2003]. This invention presents a method for producing petroleum coke by delayed coking, including heating the primary raw material, separating it into light fractions and a heavy residue in an evaporator, fractionating light fractions in a distillation column together with vapor-liquid coking products, mixing a heavy residue from an evaporator with a bottom residue of a distillation column with the formation of secondary raw materials, its subsequent coking with the production of coke and the supply of steam-gas coking products to the bottom of the distillation column. The quality and quantity of heavy coking gas oil and bottoms are controlled by changing the amount of heavy gas oil supplied as reflux to the mass transfer devices at the bottom of the distillation column.

[EP 0191207, published 08/20/1986] describes a delayed coking process in which the feedstock for the coking oven does not contain the usual heavy recycle. Removal of this stream from the coke oven feed results in an increase in the amount of liquid and a decrease in the amount of coke, depending on the amount of fresh feed to the process. The coker feedstock is first mixed with a diluent hydrocarbon fraction having a lower boiling range than conventional coker heavy recycle and then fed to the coker.

These technical solutions can be considered basic, but they do not provide the proper efficiency of the process, which can be provided by more modern installations and technological solutions.

It should be noted that the evolution of the technological process for obtaining needle coke includes the processes of weighting the raw materials, referred to as thermal condensation or thermopolycondensation.

From the prior art, a method for producing petroleum needle coke [RU 2717815, published on March 25, 2020] is known, including heating decantoil as a feedstock, mixing it in a column for the formation of secondary raw materials equipped with mass transfer devices, with recirculation to form secondary raw materials, heating secondary raw materials to coking temperatures and coking in coke ovens to produce needle coke and coking distillate, which is fed to the bottom of the distillation column for fractionation to produce hydrocarbon gas, gasoline, light and heavy coking gas oils and bottoms, coke steaming with steam and water cooling, product supply steaming and cooling into an absorber equipped with mass transfer devices to absorb high-boiling oil products and separate the products of steaming and cooling in the absorber into vapor and liquid phases, while low-boiling hydrocarbons from the upper part of the column for the formation of secondary raw materials are sent to the absorber sorber.

A known method for producing petroleum needle coke [RU 2618820, published on May 11, 2017], including mixing in an intermediate tank of heavy catalytic cracking gas oil with recirculation to form secondary raw materials, heating secondary raw materials, feeding it into the coking chamber at a coking temperature and coking to obtain coke and coking distillate, which is fed into the lower part of the distillation column for fractionation. At the same time, the extract of furfural purification of oil production is mixed with heavy catalytic cracking gas oil in the amount of 20-30% of the mixture, light or heavy coking gas oil is used as recirculation, while the recirculation ratio is 1.5-2.0. After the supply of secondary raw materials is stopped, a coolant is supplied to the coking chamber in the amount of 10-20 t/h at a temperature of 500-530°C for 6-8 hours, which can be used as light or heavy coking gas oil.

The closest technical solution is the method for obtaining petroleum needle coke [RU 2729191, published on 08/05/2020], in which the feedstock is obtained by mixing heavy pyrolysis tar (HTP) and heavy catalytic cracking gas oil (THCC), while preliminarily, the mixture of TSP and THCC is heated up to 260-340°C at a pressure of 0.2 to 0.4 MPa and are divided into light and heavy parts. Then separately heavy and separately light parts are subjected to heat treatment under different conditions. After that, the resulting heat treatment products are jointly sent to the evaporator, where the heat-treated prepared raw material is formed in the form of a heavy residue, which is sent to the column for the formation of secondary raw materials, where it undergoes rectification in a mixture with coking products and mixes with coking gas oil at the outlet of the column. The resulting mixture is sent to the coking oven and the coking chamber, in which the coking process is carried out by means of three reactors operating in parallel with alternate loading of raw materials, coking and unloading of needle coke. Gasoline fraction vapors and gaseous heat treatment products of the feedstock obtained in the distillation column are condensed and collected in a collection tank. Further, part of the gasoline fraction is fed to irrigate the upper plate of the distillation column and to recycle for mixing with light raw materials, and the other part - the balance excess is removed from the installation, while the gases from the collection tank are sent to the standard amine purification unit.

It should be noted the excessive complexity in a large number of technological apparatuses, as well as the non-optimal wiring of technological pipelines for the movement of raw materials in the specified prototype.

The technical result of the invention is the creation of a simplified installation for the production of needle coke.

The achievement of the result is ensured by the installation, which includes a feedstock heating furnace, a light feedstock evaporator, heat exchange equipment, a light feedstock separator, a thermal condensation reactor, a distillation column, a secondary feedstock heating furnace and coking chambers. The feedstock feed line is sent through the feedstock heating furnace to the evaporator, where the feedstock is separated into a light and heavy stream, while the heavy stream is sent to the distillation column through the feedstock heating furnace, and the light component, mixing with the recirculating middle distillates from the distillation column after diverting the gas fraction in the light feedstock separator is sent through the feedstock heating furnace to the thermal condensation reactor, where it is maintained at a temperature of 500-570°C and a pressure of 0.9 to 2.5 MPa, after which it is sent to a distillation column, from the cube of which the secondary feedstock is sent for coking through a furnace for heating secondary raw materials into coke chambers operating in turn. The coking gas oil is returned to the distillation column, from which the vapors of the gasoline fraction and gaseous products are removed, and the middle distillates are recycled.

In FIG. 1 shows the installation diagram, where:

1 - furnace for heating the feedstock;

2 - evaporator of light raw materials;

3 - heat exchanger;

4 - refrigerator;

5 - separator of light raw materials;

6 - thermocondensation reactor;

7 - distillation column;

8 - air cooling battery;

9 - water cooling refrigerator;

10 - separator;

11 - furnace for heating secondary raw materials;

12 - coking chamber.

Installation for the implementation of the invention is arranged as follows:

The feedstock is obtained by mixing heavy pyrolysis tar (hereinafter HTP) and heavy catalytic cracking gas oil (hereinafter TGCC) with a content of heavy gas oil in the mixture from 10 to 85% of the mass. The mixture of TSP and THCC is heated to 260-340°C at a pressure of 0.2 to 0.4 MPa in the evaporator (2) and divided into light and heavy parts, while the light part is separately removed through the heat exchanger (3) and the refrigerator ( 4) in the separator (5) subjected to heat treatment in the thermal condensation chamber (6) at a temperature of 500-570 ° C and a pressure of 0.9 to 2.5 MPa, while the residence time in the heat affected zone for the light part is from 20 to 40 min. The gases are removed from the separator (5). Having close indicators, in particular, density, flows during pumping can be mixed directly in the pipeline or using a mixing valve or similar shut-off and control device in the design, which will provide intensification of mixing in the flow when moving during pumping. The heavy part, consisting mainly of hydrocarbons with a boiling point of more than 250°C, passes through the furnace (1), heating up to over 500°C. Thus, both the light and heavy components are ultimately sent to the main distillation column (7). The heaviest components from the cube of the column (7) are secondary raw materials, sent after heating in the furnace (11) for coking in one of the coke chambers (12), in which the secondary raw materials are heated to a temperature of 500 to 535 ° C, the operating pressure is from 2.8 to 4.8 MPa. The coking products are sent to the main distillation column (7) where they are separated into a secondary raw material component, coking gas oil, coking gasoline and coking gases. The gasoline fraction vapors obtained in the distillation column and the gaseous products of heat treatment of the feedstock are condensed and collected and separated in the separator (10) after being pre-cooled in air (8) and water cooling (9) apparatuses, then part of the gasoline fraction is fed to irrigate the upper plate of the distillation column and for recycling (mixing with light raw materials), the other part (balance excess) is removed from the plant, and the gases from the collection tank are sent to the standard amine treatment unit. And the middle distillates from the main distillation column (7) are fully recycled to the separated light component of the feedstock, which is sent for heat treatment to the thermal condensation reactor (6).

The coke chamber (7) filled with coke is first steamed with water vapor, then the coke chamber is cooled with water, after which the coke is extracted. During these processes, the feed of secondary raw materials is switched to a parallel coke chamber to ensure a continuous technological process. The number of coke chambers, which should be at least two, in particular versions of the technological installation, their number is determined by the cycles of their operation and coke extraction with associated services, their volume and the volume of secondary raw materials supplied.

The achievement of the technical result is due to the following factors: unlike the prototype, a separate process heat exchanger is not used to heat the feedstock streams. The assignment of the prototype to the pre-mixing apparatus of the heating function is impractical, since in the industrial version the next furnace in the line, designed to heat three streams, will be a large enough process apparatus to provide the contact area necessary to reach a temperature of 180-250°C. At the same time, the function of simultaneous cooling of the partially withdrawn coking gas oil distillate in the inventive device is not needed, since the entire volume of medium fractions from the distillation column is returned to the recycle. An apparatus for thermal preparation of a lighter part isolated from a mixture of feedstock, as well as a prototype, is present in the scheme. However, a similar apparatus for the heavy part was abolished, since it is redundant, since the part of the raw material removed from the bottom of the separation apparatus (evaporator) can be sent to the column without additional preparation. A similar situation is with the apparatus that performs the separation of middle distillates at the outlet of the distillation column. The prototype scheme uses a solution known to the authors of the prototype from the prior art thanks to the research of the Omsk refinery, which is the previous generation in the framework of the consideration of the present invention, since it is possible to ensure the maximum involvement of middle distillates to extract from them all possible components of raw materials suitable for coking, by complete recirculation at the beginning of the cycle. It should also be noted that the Omsk plant, being one of the few serial industrial producers of needle coke in the Russian Federation, has developed more optimized solutions, which was reflected in the construction of additional and reconstruction of the existing coker units. Similarly, the claimed scheme does not need an evaporator, which is present in the prototype after separate heat treatment of the light and heavy parts of the feedstock, which are sent to the evaporator, where the gaseous heat treatment products and the liquid part are separated. In such an evaporator, according to the prototype, gaseous separation products are sent to an additional fractionating column located after the main distillation column at the outlet of middle distillates, as a volatilizing agent. However, in the case when the installation layout excludes additional separation of middle distillates, the need for an additional evaporator before the main distillation column also disappears. It must be recognized that in the present invention the main distillation column is significantly larger than in the prototype, however, the increase in the volume of the main column can be considered an insignificant factor along with the exclusion of several devices at once compared to the prototype. Thus, the technical result can be achieved, and the installation scheme is greatly simplified, which will greatly optimize both the building area and capital costs.

The invention provides the output of the product on the raw material, not below the parameters presented in the prototype:

- when the content of THCC in the mixture (THCC + TSP) is 10% - more than 22.5% wt.,

- when the content of TGCA in the mixture (TGCC + TSP) 85% - more than 25.2% of the mass.

In this case, the obtained needle coke is characterized by a score of at least 5, the quality of the coke was assessed in points according to the standard method for assessing the microstructure [Interstate standard GOST 26132-84 Petroleum and pitch cokes. Method for assessing the microstructure].

Claims (7)

1. Installation for the production of petroleum needle coke, including a feedstock heating furnace, a light feedstock evaporator, heat exchange equipment, a light feedstock separator, a thermal condensation reactor, a distillation column, a secondary feedstock heating furnace and a coking chamber, in which the feedstock supply line is guided through the feedstock heating furnace raw materials into the evaporator, where the raw materials are separated into light and heavy streams, while the heavy stream is sent to the distillation column through the feedstock heating furnace, and the light component, mixing with the recirculating middle distillates from the distillation column after the gas fraction is removed in the light feedstock separator through the heating furnace feedstock is sent to the thermal condensation reactor, where it is maintained at a temperature of 500-570°C and a pressure of 0.9 to 2.5 MPa, after which it is sent to a distillation column, from the cube of which the secondary raw material is sent for coking through the furnace for heating secondary raw materials into coke ka measures operating in turn, while coking gas oil is returned to the distillation column, from which gasoline fraction vapors and gaseous products are removed, and middle distillates are sent for recycling. 2. The petroleum needle coke production plant according to claim 1, wherein the residence time in the thermal condensation chamber of the light component of the feedstock is from 20 to 40 minutes. 3. The installation for the production of petroleum needle coke according to claim 1, in which the feedstock is obtained by mixing heavy pyrolysis tar and heavy catalytic cracking gas oil with a content of heavy gas oil in the mixture from 10 to 85% of the mass. 4. The plant for the production of petroleum needle coke according to claim 1, in which the streams of raw materials during pumping can be mixed directly in the pipeline or using a mixing valve or similar shut-off and control device in the design, which will provide intensification of mixing in the stream while moving during pumping . 5. Installation for the production of petroleum needle coke according to claim 1, in which, during coking, the raw material is heated to a temperature of from 500 to 535 ° C, the operating pressure is from 2.8 to 4.8 MPa. 6. The installation for the production of petroleum needle coke according to claim 1, in which the vapors of the gasoline fraction and gaseous products from the distillation column are collected and separated in the separator, after being cooled in air and water coolers, then part of the gasoline fraction is fed to irrigate the upper plate of the distillation column and for recycling, the other part is removed from the plant, and the gases from the collection tank are sent to the standard amine treatment unit. 7. Installation for the production of petroleum needle coke according to claim 1, in which the number of coke chambers must be at least two, and in particular versions of the technological installation, their number is due to the cycles of their operation and extraction of coke.

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