A high-QI needle coke feedstock processing distillation apparatus

Abstract

This invention discloses a distillation apparatus for processing high-QI needle coke feedstock, relating to the field of high-QI needle coke feedstock processing technology. It includes a heating furnace, a vacuum distillation column, and a fractionation column. The heating furnace is connected to the lower end of the vacuum distillation column. The top of the vacuum distillation column is a waste oil discharge end, the middle section is a mid-section oil collection system, and the lower end is a heavy phase pitch collection end. The waste oil discharge end is connected to a top vacuum pump. The mid-section oil collection system is connected to the lower end of the fractionation column. The fractionation column, from top to bottom, consists of a first fraction collection system, a second fraction collection system, and a third fraction collection system. This invention pre-treats needle coke feedstock by combining vacuum distillation and fractionation, significantly increasing the yield of needle coke feedstock.

Description

Technical Field

[0001] This invention relates to the field of high QI needle coke feedstock processing technology, specifically a high QI needle coke feedstock processing distillation apparatus. Background Technology

[0002] Needle coke is a high-quality carbon material. After being pulverized, it forms a slender, needle-like structure with excellent orientation, electrical conductivity, and thermal conductivity. It is a primary raw material for producing ultra-high-power electrodes for steelmaking and is considered a novel material. Needle coke is divided into two categories: petroleum-based and coal-based. Petroleum-based needle coke was first invented by Great Lakes Carbon in the United States and industrialized in 1968. Coal-based needle coke was extensively developed by Mitsubishi Chemical Industries in Japan in 1970. my country's development of needle coke started relatively late. Due to insufficient domestic production capacity and inconsistent quality, some factories and enterprises currently rely on imports for their needle coke needs.

[0003] The production process of needle coke includes three stages: raw material pretreatment, delayed coking, and calcination. Raw materials used to produce oil-based needle coke have low impurity content, so pretreatment is relatively simple. Coal-based needle coke contains higher levels of quinoline insolubles (QI) and other impurities. During needle coke production, mesophase microspheres are formed. These microspheres need to grow and coalesce to form the finished needle coke. However, QI and other impurities adhere to the vicinity of the mesophase, hindering the growth and coalescing of the microspheres, thus preventing the formation of a needle coke with a well-defined fibrous structure. Therefore, in actual production, the content of quinoline insolubles in the raw materials must be strictly controlled to be below 0.1%. Currently, vacuum distillation is commonly used to remove QI from the raw materials. This method is simple to operate and has low cost, but the yield of the raw materials is low. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-QI needle coke feedstock processing distillation apparatus that pre-treats the needle coke feedstock by combining vacuum distillation and fractionation, thereby significantly improving the yield of the needle coke feedstock.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-QI needle coke feedstock processing distillation apparatus includes a heating furnace, a vacuum distillation column, and a fractionation column;

[0007] The heating furnace is connected to the lower end of the vacuum distillation tower. The top of the vacuum distillation tower is the sludge discharge end, the middle end is the mid-section oil collection system, and the lower end is the heavy phase asphalt collection end. The sludge discharge end is connected to the top vacuum pump. The mid-section oil collection system is connected to the lower end of the fractionation tower. The fractionation tower consists of a first fraction collection system, a second fraction collection system, and a third fraction collection system from top to bottom.

[0008] Both the vacuum distillation tower and the fractionation tower have an insulation layer on their outer walls. Both the vacuum distillation tower and the fractionation tower have a stirrer at their lower ends to agitate the raw materials inside. A heating layer is provided on the inner side of the lower end of the tower wall of both the vacuum distillation tower and the fractionation tower to continuously provide heat to the raw materials inside the tower.

[0009] Furthermore, the sludge discharge end is connected to a sludge condenser, and 2 to 4 sludge condensers are provided.

[0010] Furthermore, the heavy phase asphalt collection end is sequentially connected to a tower bottom pump and an asphalt condenser, and the asphalt condenser is connected to an external heavy phase asphalt storage tank.

[0011] Furthermore, the first fraction collection system includes a first condenser, a first oil pump, and a first fraction storage tank; the second fraction collection system includes a second condenser, a second oil pump, and a second fraction storage tank; the third fraction collection system includes a third condenser, a third oil pump, and a third fraction storage tank; and each of the asphalt condenser, the first condenser, the second condenser, and the third condenser is provided with 2 to 4 units.

[0012] Furthermore, the stirrer includes a stirring shaft, with side stirring bars perpendicular to the stirring shaft on both sides, and the stirring shaft is driven by a motor.

[0013] The present invention also provides a method for processing high-QI needle coke feedstock using the above-described distillation apparatus, comprising the following steps:

[0014] S1: Distill the raw material to remove water under normal pressure, and heat the dehydrated raw material to 450°C in a heating furnace;

[0015] S2: The heated raw material is fed into a vacuum distillation column for vacuum distillation, separating the bottom heavy phase pitch, the middle section oil, and the top sludge oil; the pressure at the top of the distillation column is 10~15 kPa, the temperature at the top of the column is 230~250℃, and the temperature at the bottom of the distillation column is 400~420℃.

[0016] S3: The oil from the middle section of S2 is fed into the fractionation tower, and after passing through the condenser and oil pump, the upper first fraction, the middle second fraction, and the lower third fraction are obtained.

[0017] S4: The first, second, and third fractions of S3 are blended in a weight ratio of (0.5~1):(1.2~1.8):(4~5.8) to obtain the raw material for producing needle coke;

[0018] S5: The top sludge oil obtained in step S2 enters the sludge oil treatment center, and the bottom heavy phase oil enters the storage center.

[0019] Furthermore, the raw material is low-temperature coal tar pitch.

[0020] Furthermore, in step S2, the distillation temperature of the mid-section oil is 260~390℃.

[0021] Furthermore, in step S3, the boiling point range of the first fraction is 260~300℃ and the pressure is 12~25kPa; the boiling point range of the second fraction is 310~350℃ and the pressure is 28~35kPa; and the boiling point range of the third fraction is 360~390℃ and the pressure is 38~43kPa.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The distillation apparatus provided by the present invention includes a vacuum distillation tower and a fractionation tower. In the vacuum distillation tower, the middle section oil is first separated. In order to better improve the yield of needle coke feedstock, the distillation range can be set slightly larger during vacuum distillation. Most of the quinoline insolubles (QI) exist in the heavy phase pitch at the bottom of the vacuum distillation tower, and a small part exists in the middle section oil. The middle section oil is then divided into three sections in the fractionation tower, namely the first fraction, the second fraction and the third fraction. The first fraction has the lowest QI content, and the third fraction has a relatively high QI content. Through experiments, the first fraction, the second fraction and the third fraction can be blended in a certain proportion to obtain needle coke feedstock that meets the requirements (QI content is less than 0.1%).

[0024] (2) In this invention, a stirrer is provided at the bottom of both the vacuum distillation tower and the fractionation tower, which can stir the raw material at the bottom of the tower and speed up the distillation.

[0025] (3) The present invention provides an insulation layer on the outer layer of the vacuum distillation tower and the fractionation tower, which can stabilize the temperature inside the tower and avoid changes in the composition of the distillate due to temperature fluctuations, thereby obtaining needle coke raw material that does not meet the requirements; a heating layer is provided at the lower end of the vacuum distillation tower and the fractionation tower, which can heat the raw material at the bottom of the tower to reach the temperature required for distillation. Traditional raw material heating usually uses a heating furnace to circulate the raw material components or uses a heat exchanger, which requires a conveying pipeline to circulate the raw material and also requires the addition of heat exchange pipelines, thereby increasing costs. In addition, heat energy is lost during the transmission process; the present invention achieves uniform heating of the raw material at the bottom of the tower through the combined action of the heating layer and the stirrer, without the need to add heat exchange pipelines, which not only saves costs but also reduces heat energy loss. Attached Figure Description

[0026] Figure 1 This is a structural diagram of the distillation apparatus of the present invention;

[0027] Figure 2 This is a structural diagram of the stirrer in this invention.

[0028] The corresponding names of the attached figures are as follows: 1-Heating furnace, 2-Vacuum distillation column, 3-Fracturing column, 4-Motor, 5-Side stirring rod, 6-Sludge oil condenser, 7-Top vacuum pump, 8-First condenser, 9-First oil pump, 10-First fraction storage tank, 11-Second condenser, 12-Second oil pump, 13-Second fraction storage tank, 14-Third condenser, 15-Third oil pump, 16-Third fraction storage tank, 17-Bottom pump, 18-Asphalt condenser, 19-Stirring shaft. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments.

[0030] like Figure 1 As shown, this invention provides a high-QI needle coke feedstock processing distillation apparatus, including a heating furnace 1, a vacuum distillation column 2, and a fractionation column 3. The heating furnace 1 is connected to the lower end of the vacuum distillation column 2, and the heating furnace 1 is used to heat the feedstock, which needs to be dehydrated before entering the heating furnace 1. The top of the vacuum distillation column 2 is a sludge discharge end, the middle is a mid-section oil collection system, and the bottom is a heavy phase pitch collection end. The sludge discharge end is sequentially connected to a sludge condenser 6 and a column top vacuum pump 7. The column top vacuum pump 7 can extract non-condensable gases from the distillation column, and the sludge condensed by the sludge condenser 6 is transferred to a sludge treatment center for centralized processing. The intermediate oil collection system is connected to the lower end of the fractionation tower 3. From top to bottom, the fractionation tower 3 consists of a first fraction collection system, a second fraction collection system, and a third fraction collection system. The first fraction collection system includes a first condenser 8, a first oil pump 9, and a first fraction storage tank 10. The second fraction collection system includes a second condenser 11, a second oil pump 12, and a second fraction storage tank 13. The third fraction collection system includes a third condenser 14, a third oil pump 15, and a third fraction storage tank 16. The intermediate oil is separated into three fractions by the fractionation tower 3, which then pass through the condenser and oil pump sequentially before being transported to the storage tank for storage. The heavy phase asphalt collection end is connected to a bottom pump 17 and an asphalt condenser 18. The asphalt condenser 18 is connected to an external heavy phase asphalt storage tank. After vacuum distillation, the QI in the feedstock is mainly present in the heavy phase asphalt, therefore, the intermediate oil is the raw material for preparing needle coke. In addition, reflux lines are provided in the first fraction collection system, the second fraction collection system, and the third fraction collection system to return the non-condensable gas after being processed by the condenser to the fractionation tower 3. A reflux line is also provided at the top of the fractionation tower 3 to return the non-condensable gas to the vacuum distillation tower 2.

[0031] To facilitate better condensation of the various gaseous components during distillation, 2 to 4 condensers are installed for each of the following: sludge condenser 6, asphalt condenser 18, first condenser 8, second condenser 11, and third condenser 14. Both the vacuum distillation column 2 and the fractionation column 3 have insulation layers on their outer walls. Distillation requires specific pressure and temperature control within the column; the insulation layers maintain a stable temperature. A heating layer is installed on the inner side of the lower wall of both the vacuum distillation column 2 and the fractionation column 3 to continuously provide heat to the feedstock, ensuring it reaches the required distillation temperature. To ensure uniform heating of the feedstock, both the vacuum distillation column 2 and the fractionation column 3 are equipped with agitators (such as stirrers) at their lower ends to agitate the feedstock. Figure 2 As shown, the stirrer includes a stirring shaft 19, with side stirring bars 5 perpendicular to the stirring shaft 19 on both sides. The stirring shaft 19 is driven by a motor 4. The stirrer can stir the raw material at the bottom of the column, which can both accelerate the distillation speed and ensure that the raw material is heated evenly.

[0032] This embodiment provides a method for processing high-QI needle coke feedstock using the above-described distillation apparatus, comprising the following steps:

[0033] S1: Distill the raw material to remove water under normal pressure, and then heat the dehydrated raw material to 450°C in a heating furnace.

[0034] S2: The heated raw material is fed into a vacuum distillation tower for vacuum distillation, separating the bottom heavy phase pitch, the middle section oil, and the top sludge oil; the pressure at the top of the distillation tower is 10~15 kPa, and the temperature at the top of the tower is 230~250℃; the temperature at the bottom of the distillation tower is 400~420℃; the distillation temperature of the middle section oil is 260~390℃.

[0035] S3: The oil from the middle section of S2 is fed into the fractionation tower, where it passes through a condenser and an oil pump to obtain the upper first fraction, the middle second fraction, and the lower third fraction. The boiling point range of the first fraction is 260~300℃, and the pressure is 12~25kPa; the boiling point range of the second fraction is 310~350℃, and the pressure is 28~35kPa; the boiling point range of the third fraction is 360~390℃, and the pressure is 38~43kPa. Non-condensable gases processed by the condenser during fractionation are returned to the fractionation tower via a reflux line, and finally refluxed back to the vacuum distillation tower via a reflux line at the top of the fractionation tower.

[0036] S4: The first, second, and third fractions from S3 are blended in a weight ratio of (0.5~1):(1.2~1.8):(4~5.8) to obtain the raw material for producing needle coke.

[0037] S5: The top sludge oil obtained in step S2 enters the sludge oil treatment center, and the bottom heavy phase oil enters the storage center.

[0038] The first, second, and third fractions were blended according to the weight ratios shown in the table below to obtain the raw materials for producing needle coke. The content of quinoline insolubles in each raw material was tested and is shown in the table below.

[0039]

[0040] After the above three sets of experiments, the three fractions were mixed in a certain proportion, and the QI content of each fraction was less than 0.1%, which met the requirements of actual production and processing.

[0041] This invention uses low-temperature coal tar pitch as the raw material. During vacuum distillation, a distillation range larger than conventional methods is selected to obtain top sludge oil, a mid-range oil with a large distillation range, and bottom heavy phase pitch. Quinoline insolubles (QI) are mostly present in the heavy phase pitch, with a small portion in the mid-range oil. The mid-range oil is then fractionated into three sections in a fractionating column: the first fraction, the second fraction, and the third fraction. The first fraction has the lowest QI content, while the third fraction has a relatively high QI content, even exceeding 0.1%. By blending the first, second, and third fractions in a certain proportion, a needle coke feedstock that meets the requirements (QI content below 0.1%) can be obtained. This method can effectively improve the yield of needle coke feedstock.

[0042] The above embodiments are merely one of the preferred embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Any modifications or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but solve the same technical problem as the present invention, should be included within the scope of protection of the present invention.

Claims

1. A method for processing high-QI needle coke feedstock, characterized in that, Includes the following steps: S1: Distill the raw material to remove water under normal pressure, and heat the dehydrated raw material to 450°C in a heating furnace; S2: The heated raw material is fed into a vacuum distillation column for vacuum distillation, separating the bottom heavy phase pitch, the middle section oil, and the top sludge oil; the pressure at the top of the distillation column is 10~15 kPa, the temperature at the top of the column is 230~250℃, and the temperature at the bottom of the distillation column is 400~420℃. S3: The oil from the middle section of S2 is fed into the fractionation tower, and after passing through a condenser and an oil pump, the upper first fraction, the middle second fraction, and the lower third fraction are obtained. The boiling point of the first fraction is 260~300℃ and the pressure is 12~25kPa; the boiling point of the second fraction is 310~350℃ and the pressure is 28~35kPa; and the boiling point of the third fraction is 360~390℃ and the pressure is 38~43kPa. S4: The first, second, and third fractions from S3 are blended in a weight ratio of 0.5~1:1.2~1.8:4~5.8 to obtain the raw material for producing needle coke; S5: The top sludge oil obtained in step S2 enters the sludge oil treatment center, and the bottom heavy phase oil enters the storage center; The apparatus used to implement the above method includes a heating furnace (1), a vacuum distillation column (2), and a fractionation column (3); the heating furnace (1) is connected to the lower end of the vacuum distillation column (2), the top of the vacuum distillation column (2) is the sludge discharge end, the middle end is the middle section oil collection system, and the lower end is the heavy phase asphalt collection end; the sludge discharge end is connected to the top vacuum pump (7), the middle section oil collection system is connected to the lower end of the fractionation column (3), and the fractionation column (3) consists of a first fraction collection system, a second fraction collection system, and a third fraction collection system from top to bottom; The outer walls of the vacuum distillation tower (2) and the fractionation tower (3) are provided with heat insulation layers. At the lower end of the vacuum distillation tower (2) and the fractionation tower (3), a stirrer is provided to stir the internal raw materials. A heating layer is provided on the inner side of the lower end tower wall of the vacuum distillation tower (2) and the fractionation tower (3) to continuously provide heat to the raw materials in the tower.

2. The method for processing high-QI needle coke raw material according to claim 1, characterized in that, The sludge discharge end is connected to a sludge condenser (6), and there are 2 to 4 sludge condensers (6).

3. The method for processing high-QI needle coke raw material according to claim 2, characterized in that, The heavy phase asphalt collection end is connected in sequence to a tower bottom pump (17) and an asphalt condenser (18), and the asphalt condenser (18) is connected to an external heavy phase asphalt storage tank.

4. The method for processing high-QI needle coke raw material according to claim 3, characterized in that, The first fraction collection system includes a first condenser (8), a first oil pump (9), and a first fraction storage tank (10); the second fraction collection system includes a second condenser (11), a second oil pump (12), and a second fraction storage tank (13); the third fraction collection system includes a third condenser (14), a third oil pump (15), and a third fraction storage tank (16); the asphalt condenser (18), the first condenser (8), the second condenser (11), and the third condenser (14) are each provided in 2 to 4 units.

5. The method for processing high-QI needle coke raw material according to claim 1, characterized in that, The stirrer includes a stirring shaft (19), and side stirring rods (5) perpendicular to the stirring shaft (19) are provided on both sides of the stirring shaft (19). The stirring shaft (19) is driven by a motor (4).

6. The method for processing high-QI needle coke raw material according to claim 1, characterized in that, The raw material is low-temperature coal tar pitch.

7. The method for processing high-QI needle coke raw material according to claim 6, characterized in that, The distillation temperature of the mid-section oil in step S2 is 260~390℃.

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