A method and system for preparing calcined petroleum coke by delayed coking process

Abstract

The present invention belongs to the fields of metallurgy, materials and chemical industry, and relates to a method and system for preparing calcined petroleum coke by a delayed coking process. The method for preparing calcined petroleum coke comprises the following steps: rapidly heating the residual oil to 600-800°C, introducing a reducing gas for desulfurization reaction; then sending it to a calcining device for high-temperature reaction, cooling to obtain calcined petroleum coke and an oil-gas mixture; the oil-gas mixture is fractionated to obtain gasoline, diesel and wax oil. The present invention first calcines and desulfurizes the residual oil in a heating furnace at high temperature in a reducing gas, effectively removes sulfides in the oil and gas, and enhances the mechanical strength of the intermediate product. Subsequently, a high-temperature reaction occurs in the calcining device, and a pyrolysis polycondensation reaction and a structural strengthening reaction occur simultaneously, and the structure is continuously rearranged, gradually tending to be ordered and densified, and a low-sulfur calcined petroleum coke with high particle stability, low coke powder amount, high true density and high degree of graphitization is obtained to meet the needs of subsequent applications.

Description

Technical Field

[0001] The invention belongs to the fields of metallurgy, materials and chemical industry, and relates to a method and system for preparing calcined petroleum coke by a delayed coking process. Background Art

[0002] Petroleum coke is a byproduct produced during the refining of crude oil, and is generally produced by the delayed coking process. The indicators for measuring the quality of petroleum coke include volatile matter, ash content, sulfur content, and true density after calcination at 1300°C. Sulfur content is one of the important indicators for measuring the quality of petroleum coke, and the sulfur content mainly depends on the quality of crude oil. The sulfur in petroleum coke can be divided into organic sulfur and inorganic sulfur. Organic sulfur includes mercaptans, sulfides, sulfides, etc., and inorganic sulfur includes iron sulfide and sulfate. Most of the petroleum coke is organic sulfur, which can be removed at a lower calcination temperature, while inorganic sulfur needs to be decomposed and volatilized at a high temperature of graphitization. According to its sulfur content, it can be divided into high-sulfur petroleum coke (>4wt.%), medium-sulfur petroleum coke (2-4wt.%), and low-sulfur petroleum coke (<2wt.%). Petroleum coke with different sulfur contents will also be used in different fields. High-sulfur coke is mostly used as fuel for thermal power plants and cement plants, and low-sulfur coke is generally used for carbon materials such as prebaked anodes and graphite electrodes for aluminum and steelmaking.

[0003] When raw coke is used for graphite electrodes for steelmaking or anode paste (molten electrode) for aluminum and magnesium production, the raw coke must be calcined to make the petroleum coke (raw coke) meet the requirements. Calcined petroleum coke is the product of high-temperature calcination of petroleum coke. Petroleum coke calcination is an important process in the carbon production process. It is a high-temperature calcination treatment under air-tight conditions. Its purpose is to remove volatiles, moisture and part of the sulfur in the petroleum coke, increase the true density, resistivity and strength of the raw materials, and improve the chemical stability of the raw materials. During the calcination process, as the volatiles in the petroleum coke escape, the macroscopic structure and microstructure of the petroleum coke will undergo significant changes, which is specifically manifested in the improvement of the physical and chemical properties of the calcined petroleum coke.

[0004] Prior art CN201010136023.7 discloses a calcination process of petroleum coke, wherein the calcination of the petroleum coke is carried out in a pot calciner, wherein the pot body of the pot calciner is sequentially arranged as a preheating zone and 6 to 8 calcination zones from top to bottom, wherein the calcination temperature of the first calcination zone at the top is controlled within the maximum calcination temperature range of 1280 to 1300°C allowed by petroleum coke, and the calcination temperature of the second calcination zone located downstream of the first calcination zone is maintained within the maximum calcination temperature range but not higher than the calcination temperature of the first calcination zone, and starting from the third calcination zone, the calcination temperature of each calcination zone gradually decreases relative to the calcination temperature of the calcination zone at the adjacent upstream position, and the calcination temperature is reduced to the discharge temperature of 1000 to 1050°C in the most downstream calcination zone. However, the calcined petroleum coke calcined with green coke in this way has the problems of high sulfur content, excessive amount of powdered coke, and low strength. Moreover, the forged petroleum coke produced in this way is extremely unstable in the production of graphite electrodes, carbon paste products, metallurgical industry and calcium carbide, especially when used in prebaked anodes for aluminum electrolysis, which will cause excessive and deep cracks on its surface. In addition, with the consumption of anodes and electrode reactions during the electrolysis process, the excess sulfur remaining in the forged petroleum coke produced in this way will combine with oxygen to produce a large amount of sulfur dioxide, thereby reducing the conductivity of the prebaked anode and causing power consumption. Summary of the invention

[0005] The object of the present invention is to provide a method and system for preparing calcined petroleum coke by delayed coking process, so as to obtain high-quality calcined petroleum coke with less coke powder and less sulfur content at low cost and high efficiency.

[0006] In order to achieve the above technical objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing calcined petroleum coke by delayed coking process comprises the following steps:

[0008] The residual oil is quickly heated to 600-800℃, and reducing gas is introduced to carry out desulfurization reaction; it is then sent to a calcination device for high-temperature reaction, and after cooling, calcined petroleum coke and oil-gas mixture are obtained; the oil-gas mixture is fractionated to obtain gasoline, diesel and wax oil.

[0009] The temperature of conventional residual oil reduction desulfurization is below 300-500°C. However, at low temperatures, a large amount of catalyst needs to be added, and on the one hand, the catalyst is polluted, and on the other hand, the desulfurization time needs to be relatively long to reach a low concentration. The present invention heats the residual oil to 600-800°C without adding a catalyst. At this temperature, the sulfides in the form of simple sulfides, mercaptans and sulfones in the residual oil are easily reduced with reducing gases to generate hydrogen sulfide gas and removed, which has a very good desulfurization effect. Prevent sulfur from enriching in calcined petroleum coke and converting it into more complex thiophene sulfur embedded with aromatic carbon at high temperatures. Thiophene sulfur is difficult to remove and is harmful to subsequent applications. And at this temperature, the intermediate product after desulfurization becomes harder after high temperature, which helps to improve the hardness of calcined petroleum coke.

[0010] Preferably, the calcining device is a high-temperature pot-type calcining furnace.

[0011] The lining material of the high-temperature pot-type calcining furnace is a special alloy steel material, and the heating method is direct heating. The equipment can heat the material to a high temperature of 1300°C and facilitate coking.

[0012] Preferably, the reducing gas is H2 or ammonia, preferably hydrogen.

[0013] Hydrogen is cleaner and has better reducing properties than other reducing gases, and can be recycled repeatedly. Hydrogen reacts with sulfur to produce hydrogen sulfide gas, which can be easily decomposed to produce sulfur and hydrogen. Hydrogen can be returned to the desulfurization process for recycling.

[0014] Preferably, the reducing gas has a flow rate of 5-15 L / h and an introduction time of 10-30 min.

[0015] The role of introducing hydrogen is to remove organic sulfur in the residual oil. Hydrogen reacts with organic sulfur such as thiophene to generate hydrogen sulfide gas, so that organic sulfur is removed from the residual oil. At the same time, the introduction of hydrogen can also cause catalytic cracking reaction in the residual oil, thereby increasing the yield of light components in the residual oil. Too small a gas flow rate will lead to incomplete reaction, and too large a gas flow rate will cause the hydrogen to be unable to be quickly preheated to a temperature close to the heating temperature due to the high dehydrogenation temperature of the present invention, resulting in poor desulfurization effect. It will also affect the heating temperature, resulting in uneven temperature in the equipment, affecting the desulfurization effect.

[0016] If the reducing gas is introduced for too short a time, the desulfurization effect will be poor; if it is introduced for too long, energy consumption will be increased and there will be no obvious effect.

[0017] Preferably, the high temperature reaction temperature in the calcination equipment is 1150-1300°C.

[0018] At high temperatures, the covalent bonds between aromatic rings will break and reorganize, resulting in the rearrangement of aromatic rings. This rearrangement causes the originally dispersed aromatic rings to gradually gather together to form larger structural units. In addition to the rearrangement of aromatic rings, carbon atoms will also reconnect, forming new structural units through covalent bonds between carbon atoms, making the structure of petroleum coke more stable, increasing the degree of graphitization, and improving the thermal expansion coefficient, particle stability, true density, and conductivity of calcined petroleum coke; it also significantly reduces the moisture content, volatile matter content, and powder coke content of calcined petroleum coke. Too high or too low a temperature will affect the physical and chemical properties of calcined petroleum coke.

[0019] Preferably, the high temperature reaction time in the calcination equipment is 2-6 hours.

[0020] If the calcination time is too short, the overall physical and chemical properties of the calcined petroleum coke are low and do not meet the requirements for reuse; if the calcination time is too long, the material burn loss will increase and the output will decrease.

[0021] Preferably, the sulfur content of the calcined petroleum coke is less than 1%, the amount of powdered coke is less than 30%, the particle stability is greater than 80%, and the thermal expansion coefficient is less than 1.40×10 -6 / ℃.

[0022] A system for preparing high-quality calcined petroleum coke by a delayed coking process, comprising:

[0023] Residue oil storage device: it is used to store residue oil;

[0024] Heating device: used to heat the residual oil and receive the reducing gas, so that the residual oil and the reducing gas react;

[0025] Calcination device: It is used to receive the reduced residual oil and make it react at high temperature;

[0026] Reducing gas storage device: used for storing reducing gas;

[0027] Tail gas treatment device: It is used to receive the tail gas after high-temperature reaction and separate the reducing gas;

[0028] The residual oil storage device is connected with the heating device, the calcining device and the tail gas treatment device in sequence; the reducing gas storage device is connected with the heating device; and the outlet of the tail gas treatment device is connected with the heating device.

[0029] The residual oil is transported from the residual oil storage device to the heating device, where it is heated to 600-800°C. At the same time, reducing gas is introduced for reduction reaction. The obtained solid is immediately sent to the calcining device for high-temperature reaction. The solid is cooled to obtain calcined petroleum coke. The tail gas is transported to the tail gas treatment device for separation. The reduced gas and other gases obtained by separation are returned to the heating device, and other gases are discharged after treatment. The reducing gas storage device stores the reducing gas and transports the reducing gas to the heating device through a pipeline.

[0030] Preferably, the heating device is a heating furnace.

[0031] Preferably, the calcining device is a high-temperature pot-type calcining furnace.

[0032] Preferably, the system for preparing calcined petroleum coke further comprises a fractionation device for fractionating the oil and gas generated by the heating device and the calcining device.

[0033] Preferably, the inlet of the fractionation equipment is connected to the heating device and the calcining device; and the outlet is connected to the heating device.

[0034] The gasoline, diesel and wax oil obtained after oil and gas distillation are collected separately, and the remaining fractions are transported to the heating device for reduction.

[0035] Preferably, the cooling temperature of the solid after the high temperature reaction is <50°C.

[0036] The present invention is further explained below:

[0037] The present invention adopts a two-stage heating process to prepare high-quality low-sulfur calcined petroleum coke. First, the residual oil in the heating furnace is calcined and desulfurized under a reducing gas (H2) at a high temperature, and the strong affinity of H atoms and S atoms is utilized to effectively remove sulfides (sulfides, mercaptans, sulfones and simple thiophenes) in the oil and gas, which has a great desulfurization effect and enhances the strength of the intermediate product. In addition, the H2S gas generated by the desulfurization reaction also has a desulfurization effect, which further promotes the removal of sulfur from the residual oil. Subsequently, a high-temperature reaction occurs in the calcining device, and a thermal decomposition polycondensation reaction and a structural strengthening reaction occur simultaneously. The structure is continuously rearranged, gradually tending to be ordered and densified, and accompanied by the removal of volatiles and the discharge of sulfur and hydrogen, a low-sulfur calcined petroleum coke with high particle stability, low thermal expansion coefficient, high true density and high degree of graphitization is obtained, which can meet the needs of subsequent applications.

[0038] The beneficial effects of the present invention are:

[0039] 1. The method for preparing low-sulfur calcined petroleum coke of the present invention is to subject the coking raw material (residue oil) fed into the heating furnace to a desulfurization reaction under hydrogenation conditions. The reaction is carried out in existing equipment for delayed coking process. The reaction process does not involve catalyst treatment and the obtained calcined petroleum coke does not require additional petroleum coke desulfurization treatment when used in other industries. The process is simple and has high operability.

[0040] 2. The traditional high-temperature calcination desulfurization method without a catalyst requires a temperature of ≥1400°C; while the desulfurization temperature of the present invention is 800°C, which reduces the desulfurization temperature and significantly reduces the energy consumption of the desulfurization process. In addition, the present invention can directly produce calcined petroleum coke that can be used for steelmaking and aluminum smelting.

[0041] 3. The method for preparing low-sulfur calcined petroleum coke by a two-stage heating process of the present invention, the residual oil undergoes a thermal decomposition and polycondensation reaction under high temperature conditions, namely, reconnection between carbon atoms and rearrangement between aromatic rings, thereby obtaining low-sulfur, high-quality calcined petroleum coke with high particle stability (strength), low thermal expansion coefficient, and high degree of graphitization, which greatly reduces the amount of powdered petroleum coke produced.

[0042] 4. In the method for preparing calcined petroleum coke of the present invention, the H2 obtained after the tail gas produced by the desulfurization reaction is treated is circulated in the desulfurization process, thereby improving resource utilization.

[0043] 5. The method for preparing calcined petroleum coke of the present invention has a desulfurization rate of up to 99%, and obtains calcined petroleum coke with low volatile matter, low ash content, low sulfur content, high particle stability and low thermal expansion coefficient, which has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0045] Figure 1 This is a diagram of the equipment for preparing calcined petroleum coke by the delayed coking process of the present invention;

[0046] Among them, 1-residue oil storage tank, 2-heating furnace, 3-hydrogen storage cylinder, 4-high temperature tank calcining furnace, 5-vertically arranged tube furnace, 6-distillation tower;

[0047] Figure 2 A flow chart of the delayed coking process for preparing calcined petroleum coke according to the present invention;

[0048] Figure 3 This is a picture of the calcined petroleum coke sample prepared in the present invention. DETAILED DESCRIPTION

[0049] The following is further described in conjunction with specific implementation cases, but the present invention is not limited thereto. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0050] like Figure 1 As shown, a system for preparing calcined petroleum coke by delayed coking process comprises:

[0051] Residue oil storage device: it is used to store residue oil;

[0052] Heating device: used to heat the residual oil and receive the reducing gas, so that the residual oil and the reducing gas react;

[0053] Calcination device: It is used to receive the reduced residual oil and make it react at high temperature;

[0054] Reducing gas storage device: used for transmitting reducing gas;

[0055] Tail gas treatment device: It is used to receive the tail gas after high-temperature reaction and separate the reducing gas;

[0056] A fractionation device, which is used to fractionate the oil and gas generated by the heating device and the calcining device;

[0057] The residual oil storage device is connected with the heating device, the calcining device and the tail gas treatment device in sequence; the reducing gas storage device is connected with the heating device, and the gas outlet of the tail gas treatment device is connected with the heating device. The inlet of the fractionation equipment is connected with the heating device and the calcining device; and the outlet is connected with the heating device.

[0058] The residual oil is transported from the residual oil storage device to the heating device, where it is quickly heated to 600-800°C. At the same time, reducing gas is introduced for reduction reaction. The obtained solid is immediately sent to the calcining device for high-temperature reaction. The solid is cooled to obtain calcined petroleum coke. The tail gas is transported to the tail gas treatment device for separation. The reduced gas and other gases obtained by separation are transported to the heating device through a pipeline, and other gases are discharged after treatment. The reducing gas storage device transports the reducing gas to the heating device. The gasoline, diesel and wax oil obtained after oil and gas fractionation are collected separately, and the remaining fractions are transported to the heating device for reduction again.

[0059] The heating device is a heating furnace, the calcining device is a high-temperature tank-type calcining furnace, the fractionation equipment is a fractionation tower, and the reducing gas storage device is a hydrogen storage cylinder. The reducing gas is hydrogen.

[0060] Example 1

[0061] Such as process flow Figure 2As shown, atmospheric residue oil is pumped into the heating furnace, the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 600°C, hydrogen is introduced into the heating furnace, the hydrogen introduction flow rate is 5L / h, the introduction time is 10min, after the desulfurization reaction is completed, it is quickly sent to the high-temperature pot calcining furnace for calcination, the calcination temperature is 1150°C, the calcination time is 3h, after the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke, as shown Figure 3 After testing, the ash content is 0.49%, the sulfur content is 0.88%, the volatile content is 1.13%, the coke volume 0-8mm is 28.79%, the particle stability is 80.23%, and the thermal expansion coefficient is 1.38×10 -6 / ℃.

[0062] Example 2

[0063] Such as process flow Figure 2 As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 1000°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 5L / h, and the introduction time is 10min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.71%, the sulfur content is 1.12%, the volatile content is 1.18%, the powder coke amount 0-8mm is 28.43%, the particle stability is 79.56%, and the thermal expansion coefficient is 1.43×10 -6 / ℃.

[0064] Example 3

[0065] Such as process flow Figure 2 As shown, the atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 700°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 1L / h, and the introduction time is 10min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination. The calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.75%, the sulfur content is 1.67%, the volatile content is 1.56%, the powder coke amount 0-8mm is 32.98%, the particle stability is 76.78%, and the thermal expansion coefficient is 1.89×10 -6 / ℃.

[0066] Example 4

[0067] Such as process flow Figure 2As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 700°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 20L / h, and the introduction time is 10min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.45%, the sulfur content is 0.53%, the volatile content is 1.08%, the powder coke amount 0-8mm is 26.49%, the particle stability is 83.05%, and the thermal expansion coefficient is 1.34×10 -6 / ℃.

[0068] Example 5

[0069] Such as process flow Figure 2 As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 700°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 10min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.42%, the sulfur content is 0.55%, the volatile content is 1.07%, the powder coke amount 0-8mm is 26.56%, the particle stability is 82.99%, and the thermal expansion coefficient is 1.33×10 -6 / ℃.

[0070] Example 6

[0071] Such as process flow Figure 2 As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 700°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 2min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.67%, the sulfur content is 1.78%, the volatile content is 1.41%, the powder coke amount 0-8mm is 31.79%, the particle stability is 75.12%, and the thermal expansion coefficient is 1.76×10 -6 / ℃.

[0072] Example 7

[0073] Such as process flow Figure 2As shown, the atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 700°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 40min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination. The calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.39%, the sulfur content is 0.35%, the volatile content is 0.97%, the powder coke amount 0-8mm is 27.01%, the particle stability is 83.87%, and the thermal expansion coefficient is 1.25×10 -6 / ℃.

[0074] Example 8

[0075] Such as process flow Figure 2 As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 800°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C and the calcination time is 3h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.37%, the sulfur content is 0.38%, the volatile content is 0.89%, the powder coke amount 0-8mm is 26.35%, the particle stability is 83.14%, and the thermal expansion coefficient is 1.26×10 -6 / ℃.

[0076] Example 9

[0077] Such as process flow Figure 2 As shown, the atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 800°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1150°C, and the calcination time is 30min. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.51%, the sulfur content is 0.37%, the volatile content is 1.01%, the powder coke amount 0-8mm is 36.21%, the particle stability is 77.21%, and the thermal expansion coefficient is 1.71×10 -6 / ℃.

[0078] Example 10

[0079] Such as process flow Figure 2As shown, atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 800°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination, and the calcination temperature is 1400°C and the calcination time is 10h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.22%, the sulfur content is 0.41%, the volatile content is 0.52%, the powder coke amount 0-8mm is 22.36%, the particle stability is 90.56%, and the thermal expansion coefficient is 1.13×10 -6 / ℃.

[0080] Embodiment 11

[0081] Such as process flow Figure 2 As shown, the atmospheric residue oil is pumped into the heating furnace, and the residue oil flows at a high speed in the heating furnace tube and is quickly heated to 800°C. Hydrogen is introduced into the heating furnace, and the hydrogen introduction flow rate is 10L / h, and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to a high-temperature pot calcining furnace for calcination. The calcination temperature is 1300°C and the calcination time is 5h. After the coking reaction is completed, the residue in the high-temperature pot calcining furnace is cooled to <50°C and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.21%, the sulfur content is 0.32%, the volatile content is 0.56%, the powder coke amount 0-8mm is 18.78%, the particle stability is 91.43%, and the thermal expansion coefficient is 1.11×10 -6 / ℃.

[0082] Comparative Example 1

[0083] Atmospheric residue oil is pumped into the heating furnace. The residue oil flows at a high speed in the heating furnace tube and is heated to 800°C. Hydrogen is introduced into the heating furnace. The hydrogen introduction flow rate is 10L / h and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to the coking tower for coking reaction. The coking temperature is 500°C and the coking time is 28h. After the temperature in the coking tower is cooled to room temperature, the petroleum coke is taken out and tested. The ash content is 0.56%, the sulfur content is 1.34%, the volatile content is 9.89%, the powder coke amount is 60.56%, the particle stability is 64.32%, and the thermal expansion coefficient is 3.56×10 -6 / ℃.

[0084] Comparative Example 2

[0085] The catalytic oil slurry contacts the coking reaction effluent in the coking fractionation tower, and the purified oil and hydrogen mixed oil are sent to the hydrotreating system. The reaction temperature is 380℃, the reaction pressure is 7Mpa, the hydrogen-oil volume ratio is 800, and the liquid-air velocity is 0.6h -1The catalyst is Ni hydrogenation catalyst. After the desulfurization reaction is completed, it is quickly sent to the pot calciner for coking reaction. The calcination temperature is 1200℃ and the calcination time is 2h. After the coking reaction is completed, the residue in the pot calciner is cooled to <50℃ and then taken out to obtain calcined petroleum coke. After testing, the ash content is 0.78%, the sulfur content is 1.51%, the volatile content is 1.56%, the powder coke amount 0-8mm is 46.78%, the particle stability is 71.11%, and the thermal expansion coefficient is 2.56×10 -6 / ℃.

[0086] Comparative Example 3

[0087] Atmospheric residue oil is pumped into the heating furnace. The residue oil flows at high speed in the heating furnace tube and is heated to 800°C. Hydrogen is introduced into the heating furnace. The hydrogen flow rate is 10L / h and the introduction time is 30min. After the desulfurization reaction is completed, it is quickly sent to the high-temperature pot calciner for coking reaction. The coking temperature is 485°C and the coking time is 30h. After the coking reaction is completed, the residue in the high-temperature pot calciner is cooled to <50°C and then taken out, and then sent to the pot calciner. The calcination temperature is 1300°C and the reaction time is 30h to obtain calcined petroleum coke. After testing, the ash content is 0.81%, the sulfur content is 0.61%, the volatile content is 1.79%, the powder coke amount 0-8mm is 56.55%, the particle stability is 71.56%, and the thermal expansion coefficient is 3.21×10 -6 / ℃.

[0088] Table 1 Parameters of calcined petroleum coke in Examples 1-11 and Comparative Examples 1-3

[0089]

[0090] As can be seen from Table 1, in Example 2, the desulfurization temperature is higher than 1000°C, but a good desulfurization effect is not achieved, and the comprehensive performance of the calcined petroleum coke obtained is poor. This is because when the temperature is too high, the coking of the residual oil will be accelerated, and part of the residual oil will be solid after coking, resulting in a reduction in the contact surface between hydrogen and the residual oil, and the desulfurization effect is poor. In addition, the residual oil is easy to adhere to the heating furnace tube and pipeline after coking, which is easy to cause pipeline blockage, thereby affecting the calcination process. In Examples 3-4, the high or low flow rate of hydrogen introduced will affect the desulfurization effect, and it can be seen from Example 4 that when the hydrogen introduction flow rate is 20L / h, the sulfur content is only reduced by 0.02% (compared with Example 5), and the desulfurization effect is not significantly improved, but the hydrogen consumption is greatly increased, and the cost increases too much. Examples 6-7 are cases where the hydrogen introduction time is too short and too long, respectively. From Example 6, it can be concluded that the hydrogen introduction time is too short, and the amount of hydrogen required for residual oil desulfurization is not provided, resulting in insufficient desulfurization and a high sulfur content in the calcined petroleum coke. In Example 7, the hydrogen introduction time is long, but the sulfur content of the calcined petroleum coke is not further significantly reduced, but the hydrogen consumption is greatly increased, and the cost increases too much. In Example 9, the calcination time is too short, which is not enough to provide the energy required for its thermal decomposition and polycondensation, resulting in a large amount of powdered coke and poor particle stability. From the results of Example 10, it can be seen that too high a calcination temperature and a long calcination time will deteriorate the comprehensive performance of the calcined petroleum coke (compared with Example 11), and too high a calcination temperature shortens the equipment life and increases the production cost. Example 11 has the best effect. The sulfur content of the calcined petroleum coke obtained is low, the amount of powdered coke 0-8mm is 18.78%, the particle stability is as high as 91.43%, and the thermal expansion coefficient is as low as 1.11×10 -6 / ℃, indicating that hydrodesulfurization at 800℃ has a great desulfurization effect. Reconnection between carbon atoms and rearrangement between aromatic rings occur during high-temperature calcination, which greatly improves the particle stability and graphitization degree of calcined petroleum coke. The high particle stability indicates that the calcined petroleum coke has high strength and good mechanical properties. The process effect adopted in the comparative example is obviously lower than that of the process of the present invention, the effect of low-temperature hydrodesulfurization is slightly worse, and the calcined petroleum coke obtained by the staged coking process has a large amount of powdered coke and low particle stability, which does not meet the requirements of calcined petroleum coke as a carbon material for aluminum electrolysis.

[0091] In summary, the method of the present invention can be used to obtain high-quality calcined petroleum coke products with low sulfur content, small amount of petroleum coke powder, high particle stability and small thermal expansion coefficient, which provides a new path for the production of high-quality calcined petroleum coke.

Claims

1. A method for preparing calcined petroleum coke by delayed coking process, characterized in that: The method comprises the following steps: rapidly heating the residual oil to 600-800°C, introducing a reducing gas to carry out a desulfurization reaction; subsequently sending the residual oil to a calcining device for a high-temperature reaction to obtain calcined petroleum coke and an oil-gas mixture; fractionating the oil-gas mixture to obtain gasoline, diesel and wax oil; adding no catalyst during the desulfurization reaction; the high-temperature reaction temperature in the calcining device is 1150-1300°C; the high-temperature reaction time in the calcining device is 2-6h; the gas flow rate of the reducing gas is 5-15L / h, and the introduction time is 10-30min; the reducing gas is H2.

2. The method according to claim 1, characterized in that The sulfur content of the calcined petroleum coke is less than 1%, the amount of powdered coke is less than 30%, the particle stability is greater than 80%, and the thermal expansion coefficient is less than 1.40×10 -6 / ℃.

3. A system for preparing calcined petroleum coke by implementing the method for preparing calcined petroleum coke by delayed coking process according to claim 1 or 2, characterized in that: include: Residue oil storage device: it is used to store residue oil; Heating device: used to heat the residual oil and receive the reducing gas, so that the residual oil and the reducing gas react; Calcination device: It is used to receive the reduced residual oil and make it react at high temperature; Reducing gas storage device: used for storing reducing gas; Tail gas treatment device: It is used to receive the tail gas after high-temperature reaction and separate the reducing gas; The residual oil storage device is connected with the heating device, the calcining device and the tail gas treatment device in sequence; the reducing gas storage device is connected with the heating device; and the outlet of the tail gas treatment device is connected with the heating device.

4. The system according to claim 3, characterized in that The heating device is a heating furnace; the calcining device is a high-temperature pot-type calcining furnace.

5. The system according to claim 3, characterized in that The system for preparing calcined petroleum coke also includes a fractionation device, which is used to fractionate the oil and gas generated by the heating device and the calcining device.

6. The system according to claim 5, characterized in that The inlet of the fractionation equipment is connected with the heating device and the calcining device; and the outlet is connected with the heating device.

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