RU2805662C1 - Method and plant for producing petroleum needle coke by delayed coking - Google Patents

Abstract

FIELD: oil refining.

SUBSTANCE: method for producing highly anisotropic petroleum needle coke by delayed coking with thermal condensation of the feedstock. A method for producing petroleum needle coke by delayed coking is disclosed, in which heavy secondary oil products of varying degrees of sulphur contamination are simultaneously involved in processing with regulation of the ratio of various feed streams. The primary feed is heated in a furnace and then fed into a thermal condensation reactor. The bottoms of the distillation column, as well as part of the hot total feed stream, are recycled to the overhead of the reactor to maintain thermal condensation temperature. The light components from the thermal condensation reactor are routed into the distillation column, where heavy coking gas oil is also routed. In this case, in the thermal polycondensation reactor, thermal condensation of the feed occurs at a pressure of 1.2-1.8 MPa, temperature 400-480°C, and residence time of at least 30-90 minutes. Then the resulting total feed is preheated and routed for coking and partially for recycling to the thermal condensation reactor. Also disclosed is a plant for producing petroleum needle coke by delayed coking.

EFFECT: production of needle coke with preliminary heat treatment of the mixed feed in a thermal condensation reactor.

16 cl, 1 dwg, 1 tbl, 20 ex

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 with thermal condensation of raw materials.

Traditionally, decant oils - heavy catalytic cracking gas oils freed from catalyst dust from modern FCC plants - are used as raw materials for the production of needle coke. Decantoil is characterized by high density, contains a large amount of aromatic hydrocarbons, low coking ability compared to straight-run residues and a fairly light fractional composition.

The low-boiling fractions contained in the decant oil practically do not participate in coke formation; entering the coke chambers, they evaporate and are removed in the vapor phase along with the coking distillate into the distillation column. This reduces the coke yield from the initial decantoil, even when coking is carried out with a high recirculation ratio.

In addition, low-boiling fractions, when evaporated, can disrupt the hydrodynamic situation in the coke chambers, which contributes to the formation of a highly anisotropic structure of needle cokes.

A method for producing petroleum needle coke [RU 2717815, publ.: 03/25/2020] is known from the prior art, including heating decantoil as a feedstock, mixing it in a secondary raw material formation column equipped with mass transfer devices, with recycle to form secondary raw materials, heating the secondary raw materials to the coking temperature and coking in coke chambers to produce needle coke and coking distillate, which is supplied to the lower part of the distillation column for fractionation to produce hydrocarbon gas, gasoline, light and heavy coking gas oils and bottoms, steaming the coke with water vapor and cooling with water, feeding steaming and cooling products into an absorber equipped with mass transfer devices for the absorption of high-boiling petroleum products and separating the steaming and cooling products in the absorber into vapor and liquid phases, while low-boiling hydrocarbons from the upper part of the secondary raw material formation column are sent to the absorber.

There is also a known method [US 2022089955, publ.: 03/24/2022] which produces high-quality graphite/acicular quality coke with a reduced level of impurities and an improved coefficient of thermal expansion using integrated hydrotreating, catalytic cracking and coking sections, using a combination of high-paraffin hydrotreated stream VGO and CLO aromatic stream, which is then processed in the delayed coker section.

The closest solution is the method of producing petroleum coke [RF Patent No. 2209826, IPC S10B 55/00, publ. 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 the evaporator, fractionating the light fractions in a distillation column together with vapor-liquid coking products, mixing the heavy residue from the evaporator with the bottom residue of the distillation column with the formation of secondary raw materials, its subsequent coking to produce coke and 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 of the lower part of the distillation column.

However, the technical solution described in the prototype, firstly, in terms of the quality of the resulting product does not correspond to the characteristics of needle coke, and, secondly, does not use the additional capabilities of preparing raw materials for coking using the thermal condensation process.

Of course, coking of weighted raw materials, both in terms of fractional composition and density, helps to improve the structure of the produced coke and allows us to consider the possibility of producing highly anisotropic needle coke. However, stringent requirements for the quality of raw materials, limited volume(s) of available raw materials, as well as the need to modify existing delayed coking technologies focused on processing sour oil residues, do not contribute to the decision to place petroleum needle coke production processes at existing oil refineries.

The technical result of the invention is the production of needle coke with preliminary heat treatment of the raw material mixture in a thermal condensation reactor.

The technical result is achieved by solving a production technical problem - the simultaneous involvement in processing of various raw materials, the basis of which is low-sulfur heavy gas oils from secondary oil refining processes, ensuring an effective thermal condensation process. The thermal condensation process (TC) is a technology for heat treatment of mixtures of heavy raw materials of oil refining, chemical, petrochemical and coke production. The main goal of the process is to produce a mixture of heavy hydrocarbons specific in composition and quality, used as raw materials for the delayed coking process, aimed at producing premium grades of coke with an anisotropic (acicular) structure. The TC process proceeds according to a radical chain mechanism in a certain time interval at high temperatures and pressures. The main apparatus of the process is the TK reactor, which is a hollow apparatus of ideal displacement of the required volume, which does not have internal devices. The objective of the TC process is to carry out a limited number of chemical reactions of condensation of aromatic hydrocarbons included in the raw material mixture. The occurrence of target chemical reactions, as well as the occurring reactions of cracking, dealkylation of alkyl aromatic hydrocarbons, dehydrogenation, dehydrocyclization and others determine the total thermal effect of the process, its material balance and the conversion of feedstock. In order to ensure maximum yield of the target product, it is envisaged to use a recirculation scheme, which allows the use of unconverted raw materials, including heavy coking fractions, along with fresh raw materials.

The technical result is achieved by solving the technical problem of simultaneously involving in the processing of heavy gas oils of varying degrees of sulfur contamination with regulating the ratio of various raw material flows, in which the primary raw material is heated in a technological furnace, after which it is fed into a thermal condensation reactor, into the upper part of which the bottoms are also supplied as recirculate the remainder from the distillation column, and also as a recycle hot stream of the total raw material to maintain the thermal condensation temperature, light components from the thermal condensation reactor are discharged into the distillation column, where heavy coking gas oil is also discharged, while in the thermal condensation reactor thermal condensation of the raw material occurs at a pressure of 1.2- 1.8 MPa, temperature 400-480 and holding for at least 30-90 minutes, after which the resulting total raw material with preheating is sent for coking and partially for recycling into the reaction-distillation column.

Also, to ensure a technical result, an installation is required that includes at least two supply lines of various feedstocks, a technological furnace, a distillation column, at least two parallel coke chambers, as well as a technological apparatus for the formation of total raw materials, representing a thermal condensation reactor operating at a pressure of 1 ,2-1.8 MPa, to which a recycle supply line from the distillation column bottom is connected to form the total raw material, as well as a recycle line for the total raw material after passing through the heating furnace before coking.

The invention is illustrated by the circuit diagram shown in FIG. 1, on which:

The installation works as follows.

The inlet technological pipelines for supplying raw materials for the formation of primary raw materials I, equipped with shut-off and control devices, are combined into a single technological line of primary raw materials, which, passing through the technological furnace (1), is connected to the thermal condensation reactor (2). The thermal condensation reactor (2) has outputs from the upper part - for the removal of lighter products and from the lower part - from where the total raw material that has undergone thermal condensation is removed. Technological line III for the total raw material that has undergone thermal condensation is supplied through the furnace (1) to the coke chambers (3). The technological line for removing lighter products from the thermal condensation reactor (2) is connected to a distillation column (4), which in turn has outputs for various fractionation products; at least from it, coking gases are removed via technological lines - V, coking gasoline VI ( naphtha), VII - light gas oil, VIII - heavy gas oil, as well as process line II, through which the bottoms are fed as recycle to the upper part of the thermal condensation reactor. The removal of gaseous products from the upper part of the distillation column (4) includes a sequential cooling device (5) and a separator (6) for separating flows V and VI, while the naphtha flow VI is partially returned to reflux the distillation column (4). Process line III has an outlet for partial recycle after heating furnace 2 into the thermal condensation reactor (2).

Removal can be carried out, in particular, with a design in which additional devices are installed at each outlet to ensure the purity of certain products. For example, these could be stripping sections. In this case, the withdrawn fractionation products are sent for sale or further processing, or are involved in other oil refining processes.

To compensate for the parameters, given that the pressure in the thermal condensation reactor (2) and in the distillation column (4) are significantly different, a regulating compensation device, for example a throttling device, is provided.

In addition to what was described above, the process plant must have a system for preparing the raw material mixture, including storage tanks, piping, dynamic equipment, etc.; at least two parallel coke chambers, providing the possibility of alternate filling, steaming, cooling and servicing of devices; other auxiliary systems (not the subject of the invention).

The technological heating furnace is designed in such a way that it simultaneously heats parallel flows directed through different technological pipelines - the flow of a mixture of different types of raw materials before feeding into the thermal condensation reactor (2), and the flow of the total raw materials before feeding into the coke chambers (3). The difference in temperature of different streams is determined by different areas of contact with the heating medium, provided through the lengths of sections of process pipelines inside furnace 1.

The method is carried out as follows.

Primary raw materials (I) - a composition-balanced raw material mixture is heated in a technological furnace (1) and enters a thermal condensation reactor (2), consisting of a feed zone (the area of direct input of raw materials), a reaction zone (lower - bottom part) and a rectification zone ( the upper part, equipped with contact devices and subject to irrigation with petroleum products). Thermal gas oil is the bottom product of a thermal condensation reactor, is heated in a technological furnace to 520-530°C and, as the total coking raw material (III), enters unheated coke chambers (3), part of the thermal gas oil is separately heated in the furnace and returned to the thermal condensation reactor, providing the required thermal condensation process mode. The resulting light petroleum products leave the reaction zone in the vapor phase, are combined with vapors of light components of the primary raw material in the feed zone of the thermal condensation reactor, pass through the fractionation zone together and enter the distillation column. As irrigation, secondary coking raw materials (II) from the bottom part of the distillation column are supplied to the fractionation zone into the thermal condensation reactor.

Coking vapors from the coke chambers (3) enter the feed section of the distillation column (4). Most of the coking products entering the column during the rectification process condense and form secondary coking raw materials, part of the flow is returned to the fractionation column as reflux, and part is supplied to the rectification zone of the thermal condensation reactor.

The remaining, non-condensed steam-gas coking products are subjected to fractionation in a distillation column. The upper product is cooled in a refrigerator (5) and separated in a separator (6). Coking gases (V) and coking gasoline (VI) are subject to further stabilization and processing (not the subject of the invention and are not considered in this work), light coking gas oil (VII) and heavy coking gas oil (VIII) after cooling are removed from the installation as components of diesel fuel. and liquid fuels, respectively.

Thus, according to the invention, the simultaneous involvement in processing of various raw materials is realized, which implies an increase in the raw material base in the production of anisotropic needle coke. The primary feedstock stream is formed as a mixture, in particular, of heavy catalytic cracking gas oils - hydrotreated and without hydrotreating, or other heavy petroleum products from secondary processes of oil refining and petrochemical production. To avoid the entry of undesirable components (mechanical contaminants) into technological devices, raw material flows undergo mechanical purification and (or) settling, and are accumulated in storage tanks. The number and weight and dimensions of coking chambers are determined by technological feasibility, the weight and dimensions of the remaining devices are determined in accordance with the productivity of the installation for processed raw materials and technological calculations.

The coke chamber filled with coke is first steamed with water steam, then the coke chamber is cooled with water, after which the coke is extracted. During these processes, the supply of total raw materials is switched to a parallel coke chamber to ensure a continuous technological process. The number of coke chambers, which at least must be at least two, in particular versions of the process plant is determined by the cycles of their operation and coke extraction with associated services, their volume and the volume of total raw materials supplied.

Within the framework of this invention, the quantitative characteristics of the total coking raw material (III) are provided by the supply of secondary raw materials (II) and primary raw materials (I) in the ratio III/II/I as 1.00/0.55…0.70/0.35… 0.50. The qualitative characteristics of the total coking raw material are achieved through the selection of the primary raw material recipe, as well as the technological regime of thermal condensation, carried out at a temperature of 400-480°C, a pressure of 1.2-1.8 MPa and a time of 0.5-1.5 hours. The coking process takes place at a temperature of 450-500°C, a pressure of 0.3-0.5 MPa and a time of 36-48 hours.

In relation to the prototype, the implementation of the proposed method makes it possible to obtain highly anisotropic coke of a needle-like structure with predetermined characteristics in terms of structure and proportion of heteroelements, which is achieved by compounding the initial raw material mixture, a highly efficient method of heat treatment immediately before the coking process itself, as well as due to temperature and time conditions coking process.

As an option, it is possible to implement the invention, 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 of the lower part of the distillation column.

As an option, it is possible to implement the invention in which the recycle is a bottoms residue mixed with heavy gas oil, separately removed through the stripping section from the distillation column, followed by mixing in the process pipeline before being fed into the upper part of the thermal condensation reactor.

The implementation of the invention is illustrated by a number of examples.

The flow ratio, according to the invention, during the experiments was selected with a recirculation coefficient III/I of 1.8...3.0 (the flow ratio before feeding to coking, taking into account the recycle from the distillation column and the recycle of the weighted raw material after heating after thermal condensation). In order for the volume of recirculate to be carried out from the distillation column, its supply to the thermal condensation reactor in relation to the primary raw material is carried out within the range of 1/0.4...0.8. Raw material flows A, B, C at the entrance to the installation were used as feedstock, respectively: decantoil cat. cracking, heavy gas oils from secondary processes, residual (contaminated) oil refining feedstock.

The quality of coke was assessed in points according to the standard method for assessing the microstructure [Interstate standard GOST 26132-84 Petroleum and pitch cokes. Microstructure assessment method].

Examples 1-6 show the characteristics of the resulting coke using various feed ratios, but without recirculation. The resulting product yield and coke grade can then be compared with the results that were achieved when implementing the method and installation layout according to the invention. The coking parameters were kept the same: temperature 480°C, pressure 2.03 MPa.

The data from the experiments carried out are grouped in table. 1.

Example 1.

Ratio of raw material flows A/B/C=100/0/0 (the highest quality and rarest raw materials are involved, without additional raw material flows).

Thermal condensation temperature is 450°C.

Thermal condensation pressure is 2.03 MPa.

Thermal condensation time - 60 min.

As a result, the coke yield is 35%, the coke quality is 5.4 points.

Examples 2-6.

They were carried out under similar operating parameters of the process equipment, but with the involvement of additional raw material flows. At the same time, there was a decrease in coke quality to 5.1...5.3 points, as well as in yield - to 31...34%. In addition, with this approach to implementation, it was necessary to ensure forced maintenance of the thermal condensation temperature in the reactor.

According to all the experiments given below, it was possible not only to increase the yield of the product, but also to obtain Super Premium quality coke, with a grade above 5.5, namely about 5.7.

Example 7.

Ratio of raw material flows A/B/C=60/30/10.

Thermal condensation temperature is 400°C.

Thermal condensation pressure is 1.4 MPa.

Thermal condensation time - 60 min.

Recirculation coefficient III/I=2.5.

Coking parameters: temperature 250°C, pressure 0.4 MPa, time 2520 min.

As a result, the coke yield is 34.7%.

Examples 8-20 were carried out with similar parameters, but with minor deviations, noted below and given in table. 1. During their implementation, a coke yield of 34-35% was ensured.

Example 8 - similar, with the only difference that the thermal condensation temperature was 480°C.

Example 9 - similar, with the only difference that the thermal condensation pressure was 1.2 MPa.

In examples 10-20, the thermal condensation temperature was maintained at 440°C.

Example 10 - similar, with the only difference that the thermal condensation pressure was 1.8 MPa.

Example 11 - similar, with the only difference that the thermal condensation time was 30 minutes.

Example 12 - similar, with the only difference that the thermal condensation time was 90 minutes.

Example 13 - similar, with the only difference that the recirculation coefficient was 1.8.

Example 14 - similar, with the only difference that the recirculation coefficient was 3.0.

Examples 15-20 were implemented with changing coking parameters, namely: at a temperature of 450°C and 500°C, at a pressure of 0.3 and 0.5 MPa, with an increase in coking time to 2880 minutes and a decrease to 2160 minutes.

Claims (16)

1. A method for producing petroleum needle coke by delayed coking, in which heavy secondary oil products of varying degrees of sulfur contamination are simultaneously involved in processing with regulation of the ratio of various raw material flows, in which the primary raw material is heated in a furnace, and then fed into a thermal condensation reactor, in the upper part of which the bottom residue from the distillation column is also supplied as recycle, and also part of the hot flow of the total raw material is supplied as recycle - to maintain the thermal condensation temperature, light components from the thermal condensation reactor are discharged into the rectification column, where heavy coking gas oil is also discharged, while in the thermopolycondensation reactor thermal condensation of the raw material occurs at a pressure of 1.2-1.8 MPa, a temperature of 400-480 ° C and holding for at least 30-90 minutes, after which the resulting total raw material with preheating is sent for coking and partially for recycling into the reactor thermal condensation. 2. The method according to claim 1, in which heavy gas oil streams are subjected to purification from mechanical impurities and settling. 3. The method according to claim 1, in which the temperatures of different flows are determined by different areas of contact with the heating medium, provided through the lengths of sections of process pipelines for the movement of various raw materials inside the process furnace. 4. The method according to claim 1, in which the stream of primary raw materials is formed from catalytic cracking gas oils - hydrotreated and without hydrotreating and other heavy petroleum products of secondary processes of oil refining and petrochemical production. 5. The method according to claim 1 in which the volume of recirculate from the distillation column is supplied to the thermal condensation reactor in relation to the primary raw material in the range of 1/0.4...0.8. 6. The method according to claim 1 in which the total raw material is sent for coking, which takes place at a temperature of 450-500°C, a pressure of 0.3-0.5 MPa for 36-48 hours. 7. The method according to claim 1 in which the yield of needle coke is 34-35%. 8. The method according to claim 1, in which the products removed from the top of the distillation column are cooled in a refrigerator and separated in a separator. 9. The method according to claim 1, in which the number and weight and dimensions of the coking chambers are determined by technological feasibility, the weight and dimensions of the remaining devices are determined in accordance with the productivity of the installation for the processed raw materials. 10. The method according to claim 1, in which the number of coke chambers, which at least must be at least two. 11. The method according to claim 1, in which the coke chamber filled with coke is first steamed with water steam, then the coke chamber is cooled with water, after which the coke is extracted. 12. The method according to claim 1, in which the quantitative characteristics of the total coking raw materials are provided by the supply of secondary raw materials, which is a recycle from the distillation column bottom, a recycle of thermally condensed additionally heated total raw materials and primary raw materials in the ratio total coking raw materials / recycle from the distillation column bottom / primary raw materials in the ratio 1.00/0.55…0.70/0.35…0.50. 13. The method according to claim 1, in which the amount of heavy coking gas oil and bottoms residue during the formation of recirculate is controlled by changing the amount of heavy gas oil supplied as irrigation to the mass transfer devices of the lower part of the distillation column. 14. The method according to claim 1, in which the recycle is a bottoms residue mixed with heavy gas oil, separately removed through the stripping section from the distillation column, followed by mixing in the process pipeline before being fed into the upper part of the thermal condensation reactor. 15. The method according to claim 1 in which the ratio of total raw materials and primary raw materials is implemented with a recycling coefficient of 1.8...3.0. 16. Installation for producing petroleum needle coke by delayed coking with thermopolycondensation of raw materials, which includes at least two supply lines of various feedstocks, a heating furnace, a distillation column, at least two parallel coke chambers, as well as a technological apparatus for the formation of total raw materials, representing a reactor thermopolycondensation, operating at a pressure of 1.2-1.8 MPa, to which, to form the total raw material, a recycle supply line from the distillation column bottom is connected, as well as a recycle line from the supply line for coking of the total raw material after passing through the heating furnace.

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