CN1872963A - Method of treating raw material for producing acerate coke - Google Patents

Abstract

A raw material pretreatment method for producing needle coke. The raw material oil is firstly subjected to vacuum distillation to remove non-ideal components, and the remaining ideal components are contacted with hydrogen and a hydrogenation catalyst, and the hydrogenation reactant stream is separated to produce needle coke. Burnt ingredients. Through the combination of two processes, this method can remove light and heavy non-ideal components in raw oil, make more reasonable use of hydrogen, save investment, keep ideal components to the greatest extent, and the treated raw oil meets the production requirements. Coke raw material requirements.

Description

A raw material pretreatment method for producing needle coke

                      

The invention belongs to a multi-step process method for distilling hydrocarbon oil and refining hydrocarbon oil with hydrogen, more specifically, it is a raw material pretreatment method for producing needle coke.

technical background

Needle coke has the advantages of low coefficient of thermal expansion (CTE), high degree of crystallization, and high electrical conductivity. The pores in the coke block are uniformly oriented and elongated and elliptical. Needle coke can be used as an important raw material for the production of ultra-high-power and high-power graphite electrodes, and has a wide range of uses in industry, national defense, medical and aerospace fields. At present, the output of needle coke (raw coke) in my country is about 15,000 tons, which cannot meet the demand, and about 45,000 tons of needle coke (cooked coke) still needs to be imported. Although it is a product of the delayed coking process, compared with the production of general coke, it has special requirements for raw materials and processes. First of all, the production technology of needle coke is the formation mechanism of mesophase small spheres. Colloids and asphaltenes are macromolecular condensed ring compounds with long side chains, which will hinder the formation of needle coke with fine fibrous structure; secondly, the sulfur content in needle coke It must be low, because the operating temperature of the graphitization furnace is extremely high, and the typical graphitization temperature is about 2800 ° C. Therefore, during the graphitization process, along with the escape of sulfur, crystal expansion occurs, and finally the strength of the graphite electrode is seriously damaged.

According to the nature and formation mechanism of needle coke, raw materials with low sulfur, low asphaltenes, low colloids and low ash content should be selected. Generally, catalytic cracking clarified oil and thermal cracking residue are used. However, most of these raw materials have various problems, such as high impurity content such as asphaltene, colloid and ash, and high sulfur content. If these problems cannot be dealt with in a timely and effective manner, the raw materials for producing needle coke will be greatly limited, so large-scale industrial production cannot be satisfied, and qualified needle coke cannot be produced. Therefore, how to obtain qualified raw materials for the production of needle coke has always been a subject of research.

US4178229 discloses a method for producing high-quality petroleum coke from straight-run vacuum residue. First, the vacuum residue is converted into distillate oil and asphalt, and then the asphalt and hydrogen donor are further cracked to produce high-quality coke raw materials.

US4235703 discloses a method for producing high-quality coke from residual oil. In this method, the raw material is subjected to hydrodesulfurization and demetallization, and then a delayed coking process is performed to produce high-power electrode coke.

US4894144 discloses a method for simultaneously preparing needle coke and high-sulfur petroleum coke. It adopts a hydrotreating process to pretreat straight-run heavy oil. The hydrogenated residue is divided into two parts, which are coked and then calcined to obtain needle coke State coke and high sulfur petroleum coke.

US5286371 also discloses a hydrogenation treatment process for straight-run residual oil. The hydrogenation reaction temperature is 379-480°C and the reaction pressure is 6.8MPa-34.4MPa. The stream after asphalt is used as the raw material of needle coke.

CN1325938A discloses a method for producing needle-shaped petroleum coke with sulfur-containing atmospheric residue. In this method, the raw materials are sequentially subjected to hydrorefining, hydrodemetallization, and hydrodesulfurization, and the hydrogenated oil obtained by separating hydrogenation to generate oil Hydrogen heavy distillate oil enters the delayed coking unit, and needle coke is obtained under the conditions of needle coke production. Hydrogenation is carried out at a reaction temperature of 350-420°C, a hydrogen partial pressure of 5.0-22.0MPa, and a hydrogen-oil ratio of ^500-1200Nm3 / ^m3 react under conditions.

The main problem in the above-mentioned prior art is that the non-ideal components such as asphaltenes and colloids in the raw oil are not removed but participate in the hydrogenation process, the hydrogen is not effectively utilized, and because the severity of the hydrogenation is relatively High, resulting in the loss of aromatics, the ideal components in the feedstock.

Contents of invention

The purpose of the present invention is to provide a raw material pretreatment method for producing needle coke on the basis of the prior art, to remove the non-ideal components in the raw material oil, while keeping the aromatic content of the ideal components from being reduced, so that the treated The raw material oil meets the requirements for producing needle coke raw materials.

The raw material pretreatment method for producing needle coke provided by the present invention comprises:

The raw material oil is firstly decompressed to remove the non-ideal components, and the remaining ideal components are contacted with hydrogen and hydrogenation catalyst, and the hydrogenation reactant stream is separated to obtain the raw material for producing needle coke.

The method of the present invention can remove the light and heavy non-ideal components in the raw material oil through the combination of the two processes, utilize hydrogen more rationally, save investment, keep the ideal components to the greatest extent, and the treated raw material oil meets the requirements of Raw material requirements for the production of needle coke.

Description of drawings

The accompanying drawing is a schematic diagram of the raw material pretreatment method for producing needle coke provided by the present invention.

Detailed ways

Method provided by the invention is implemented like this:

The raw material oil is firstly removed by filtration and vacuum distillation to remove heavy non-ideal components such as asphaltene, colloid and part of ash, and light non-ideal components such as diesel fraction, wherein the light non-ideal components are removed from the top of the vacuum tower The heavy non-ideal components are extracted from the bottom of the tower, and the remaining ideal components are extracted from the tower to contact with hydrogen and hydrogenation catalysts, and the hydrogenation reactants are separated to obtain the raw materials for producing needle coke.

The feed oil of the present invention is selected from one or more of heavy distillate oil, catalytic cracking oil slurry or clarified oil, steam cracking residue, and thermal cracking residue, wherein the heavy distillate is a wax oil fraction with a distillation range of 270 ~500°C. The sulfur content of the raw oil is greater than 0.6% by weight, and the higher the sulfur content in the raw oil involved in the present invention, the more the technical advantages of the present invention are displayed. If the raw oil is catalytic cracking oil slurry or clarified oil, it must be filtered first to remove catalyst powder and reduce ash; if the raw oil is heavy distillate oil, steam cracking residue, thermal cracking residue, it is not necessary to filter it first .

The filtration conditions of the present invention are pressure of 0.2-5.0 MPa and temperature of 40-350°C.

The vacuum distillation in the present invention is one-stage or multi-stage distillation, and the operating conditions are a pressure of 5mmHg-100mmHg and a temperature of 300-450°C. The ideal component boiling range obtained by distillation under reduced pressure is: 5% not less than 380°C, 95% not greater than 485°C. Among them, heavy non-ideal fractions, light non-ideal components and ideal components account for 10-15%, 0-5%, and 80%-90% of the raw oil, respectively.

The hydrogenation reaction desulfurization of the present invention is characterized by high temperature and low pressure, and the purpose is to remove sulfur while maintaining its aromatic content. The reactor adopts a fixed bed, and the active components of the hydrogenation catalyst are metals, metal oxides, and metal sulfides of VIB, VIIB, and VIIIB group elements, wherein the VIB group elements are Mo and W, the VIIB group elements are Mn, and the VIIIB group elements are Ni, Co, Fe. The reaction temperature is 300-420°C, the reaction pressure is 1.5-5.0MPa, the hydrogen-oil ratio is 50-500Nm ³ /m ³ , and the volume space velocity is 0.5-5h ^-1 . The desulfurization rate of raw oil reaches 30-70%.

At the bottom of the vacuum tower, the temperature of the bottom of the tower is reduced by adding supercooled residue to prevent coking and reduce the viscosity of the bottom material. The product is withdrawn as raw material for the production of ordinary coke.

The present invention utilizes the combination process of filtration system, vacuum distillation and mild hydrogenation to realize the pretreatment of needle coke raw materials. First, the ash is removed through the filtration system, and then the heavy non-ideal components such as asphaltenes, colloids and some ash and light non-ideal components such as diesel light fractions are removed through the vacuum distillation process. Due to the rich short side chains, Polycyclic aromatic hydrocarbons with 3 to 4 rings are good raw materials for producing needle coke, so set the minus line to extract lighter components. 80% to 90% of the raw oil is extracted from the middle, and then hydrogenated gently, and the hydrogenation depth does not need to reach the depth of residual oil hydrogenation. The present invention can remove the light and heavy non-ideal components in the raw oil through the combination of the two processes, which is more reasonable to use hydrogen than the combined process of hydrogenation first and then solvent deasphalting, saving investment, purification and maximum retention Ideal component.

Below in conjunction with accompanying drawing the method provided by the present invention is further described, and underpressure distillation in the inventive method is one-stage distillation, but is not limited to one-stage distillation, and multi-stage distillation is also applicable to the present invention.

The accompanying drawing is a schematic diagram of the raw material pretreatment method for needle coke production provided by the present invention, in which many necessary equipment such as pumps are omitted.

The raw material oil enters the buffer tank 4 through the pipeline 1, is pressurized by the pump and then enters the filter system through the pipeline 5, and the filtered raw material is heated in the radiation section of the heating furnace 6. Then the raw oil enters the decompression tower 8 through the pipeline 7, and the stripping steam required by the decompression tower 8 enters at the bottom of the tower. In order to prevent coking in the tower due to decomposition, condensation and other reactions of the residue at the bottom of the tower or cannot be discharged due to high viscosity, the supercooled vacuum residue is introduced from the bottom of the tower through pipeline 3 to reduce the temperature at the bottom of the tower and reduce the tendency of the residue to decompose and coke . The oil and gas at the top of the tower is led out through pipeline 9, and a circulating reflux system is installed on the upper part of the decompression tower. The stream is pumped out on the third tray, and returns to the top of the tower after being cooled by heat exchange. . The raw oil after vacuum distillation is pumped out and mixed with the circulating hydrogen from the pipeline 11, and then enters the heating furnace 16 through the pipeline 12. In the heating furnace 16, the raw oil is heated to a reaction temperature of 300-420°C, and then enters the hydrogenation reaction The device 13 performs gentle hydrodesulfurization, and the refined raw oil is cooled and separated into two phases of vapor and liquid in the high-pressure separation tank 17. The gas phase is compressed by the hydrogen compressor 20 and mixed with fresh hydrogen from the pipeline 19 for recycling. The needle coke raw material passes through the pipeline 18 to the needle coke production process.

The following examples will further illustrate the method, but the method is not limited thereby.

Utilize the method of the present invention to process the catalyzed clarified oil as shown in table 1, filter condition is pressure 1.0MPa (gauge pressure), temperature 250 ℃; Underpressure distillation operation condition is pressure 20mmHg, furnace outlet temperature 400 ℃, underpressure distillation material The distribution is shown in Table 2; the active components of the hydrogenation catalyst are Ni and W. The hydrogenation reaction temperature is 380°C, the reaction hydrogen partial pressure is 2.5MPa, the hydrogen-to-oil ratio is 300Nm ³ /m ³ , and the volume space velocity is 0.8h ^-1 .

The experimental results are shown in Table 1. Comparing the data in Table 1 and Table 3, it can be seen that after filtration, vacuum distillation, and mild hydrogenation, the catalytic clarified oil can meet the requirements of needle coke raw materials.

Table 1. Changes in properties of catalytic clarified oil before and after refining in the raw material pretreatment process Oil name Catalytic clarified oil Clarified oil after vacuum distillation Needle coke raw material Density (20℃), g/ ^cm3 1.0486 1.0384 1.0323 Kinematic viscosity (80℃), mm ² /s 159.32 78.23 78.24 Kinematic viscosity (100℃), mm ² /s 50.04 26.52 26.54 Carbon residue, m% 12.28 6.16 6.16 Ash content, m% 0.116 0.008 0.003 Elemental analysis, m% C 90.20 90.10 90.10 h 8.35 8.74 9.30 S 1.18 0.92 0.37 N 0.27 0.24 0.23 Hydrocarbon composition, m% saturated hydrocarbon 29.9 36.7 36.7 Aromatics 52.7 53.4 53.4 colloid 12.6 9.9 9.9 Asphaltenes 4.8 <0.1 <0.1 Distillation range, ℃ initial boiling point 276 358 335 5% 387 405 390 10% 427 424 418 30% 446 443 436 50% 463 456 447 70% 477 467 460 90% 499 478 472 95% 525 485 483

Table 2. Material distribution of catalytic clarified oil vacuum distillation Vacuum distillation Yield, w% Distillate oil (ideal component) 80.2 Minus line (light non-ideal components) 2.3 Residual oil (heavy non-ideal fraction) 17.5 total 100.0

Table 3. Raw material requirements for needle coke project index Density (20℃), g/ ^cm3 ≮1.03 Ash content, ppm ≯100 Aromatics, m% ≮45 Asphaltenes, m% ≯1 Sulfur content, m% ≯0.5

Claims (7)

1. A raw material pretreatment method for producing needle coke, characterized in that the raw material oil is first subjected to vacuum distillation to remove non-ideal components, and the remaining ideal components are contacted with hydrogen and hydrogenation catalyst, and the hydrogenation reactant flows through Raw materials for needle coke production are obtained by separation. 2. The method according to claim 1, characterized in that the raw oil is selected from one or more of heavy distillate oil, catalytic cracking oil slurry or clarified oil, steam cracking residue, and thermal cracking residue. 3. The method according to claim 1, characterized in that the feedstock oil is filtered before vacuum distillation, and the filtering conditions are pressure of 0.2-5.0 MPa and temperature of 40-350°C. 4. The method according to claim 1, characterized in that the vacuum distillation operation conditions are a pressure of 5 mmHg to 100 mmHg and a temperature of 300 to 450 °C. 5. The method according to claim 1, characterized in that the active components of the hydrogenation catalyst are metals, metal oxides, and metal sulfides of VIB, VIIB, and VIIIB group elements, wherein the VIB group elements are Mo, W, and VIIB group elements The element is Mn, and the group VIIIB elements are Ni, Co, and Fe. 6. The method according to claim 1, characterized in that the hydrogenation reaction temperature is 300-420°C, the reaction pressure is 1.5-5.0MPa, the hydrogen-oil ratio is 50-500Nm ³ /m ³ , and the volume space velocity is 0.5-5h ^-1 . 7. The method according to claim 1, characterized in that supercooled residual oil is added at the bottom of the vacuum tower, and the temperature of said supercooled residual oil is 100-350°C.