Preparation system and preparation method for producing needle coke pre-calcined coke from pure ethylene tar

Abstract

The invention belongs to the field of oil-based needle coke preparation, and particularly relates to a preparation system and a preparation method for producing pre-calcined needle coke from pure ethylene tar. In the preparation process for producing the pre-calcined needle coke, the optimal pre-calcined coke process parameters are determined by adopting a thermogravimetric analysis means on the pure ethylene tar; a heating furnace coil and a conveying pipeline are prevented from being blocked by the pure ethylene tar in the pre-calcined coke process, continuous feeding of raw materials is achieved, and the oil-based needle coke with ash content, volatile components, true density, sulfur and nitrogen meeting the pre-calcined coke standard of the oil-based needle coke is prepared; and the coker gasoline, the coker diesel oil and the coker gas oil which are byproducts obtained in the preparation process all meet related standards, so that the economic benefit is improved, and the use requirements of all stages are met.

Description

Technical Field

[0001] The invention belongs to the field of oil-based needle coke preparation, in particular to a system and a method for preparing needle coke pre-calcined coke using pure ethylene tar. Background Art

[0002] Needle coke is a carbon material with a special structure. Ultra-high power graphite electrodes produced with needle coke have the advantages of low resistivity, small thermal expansion coefficient, and good thermal shock resistance. They are used in high-power or ultra-high-power electric furnace steelmaking, which can greatly shorten the smelting time and save electricity. Ethylene tar is composed of hundreds of compounds composed of C, H elements and very small amounts of S, N, and O elements, mainly composed of C9-C90 fractions, with a wide distillation range and extremely complex material structure. However, needle coke prepared from ethylene tar is very easy to clog heating furnace coils and large oil and gas pipelines. Therefore, the present application proposes a method for producing needle coke pre-calcined coke using pure ethylene tar to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to provide a system and method for preparing needle coke pre-calcined coke from pure ethylene tar. By adopting a thermogravimetric analysis method to the pure ethylene tar, the optimal pre-calcined coke process parameters of the present invention are strictly controlled to prevent the pure ethylene tar from clogging the heating furnace coil and the conveying pipeline during the pre-calcined coke process, so as to achieve continuous feeding of raw materials, prepare oil-based needle coke whose ash content, volatile matter, true density, sulfur and nitrogen all meet the pre-calcined coke standards of oil-based needle coke, and the by-products coking gasoline, coking diesel and coking wax oil obtained in the preparation process all meet the relevant standards, thereby improving the economic benefits and meeting the use requirements of various stages.

[0004] In order to solve the above technical problems, the present invention provides a preparation system for producing needle coke calcined coke from pure ethylene tar, comprising a heating furnace and a coking tower, wherein a heat exchange tube bundle is penetrated in the heating furnace, a feed pipe is externally connected to the feed end of the heat exchange tube bundle, and a discharge end is connected to the bottom feed port of the coking tower through a feeding pipe, and the feed pipe is respectively connected to a water injection system and an oil feeding system, wherein the water injection system comprises at least one water injection tank and a steam regenerator, wherein the water injection tank is connected to the feed end of the steam regenerator through a conveying pipe, and the discharge end of the steam regenerator is connected to the feed pipe, and the oil feeding system comprises at least one oil tank, and each of the oil tanks is connected to the feed pipe through an oil feeding pipe.

[0005] Preferably, the coking tower is connected to a distillation tower, a flash tower one and a flash tower two in sequence through pipelines, the bottom discharge port of the distillation tower is connected to several heavy oil tanks, the bottom discharge port of the flash tower one is connected to several light oil tanks, the bottom discharge port of the flash tower two is connected to several light oil tanks, and the top gas outlet of the flash tower two is connected to an exhaust gas treatment device.

[0006] On the other hand, the present invention also provides a method for preparing needle coke calcined coke from pure ethylene tar, which is prepared by using any one of the above-mentioned systems for preparing needle coke calcined coke from pure ethylene tar. The method comprises the following steps:

[0007] S1. Feed

[0008] The water injection system is turned on, and the softened water in the water injection tank is converted into steam through the steam regenerator and then transported to the heating furnace through the feed pipeline;

[0009] Then the oil inlet system is turned on to transport the pure ethylene tar in the oil tank to the heating furnace through the oil delivery pipeline and the feed pipeline;

[0010] S2. Generation of needle coke before calcination

[0011] The mixed oil and water are heated in a heating furnace and transported to the coking tower from the bottom feed port through a feeding pipeline. The temperature in the coking tower is controlled at 380-480°C by thermogravimetric analysis of pure ethylene tar. Needle coke pre-calcined coke is formed through the conversion of the carbonaceous intermediate phase and airflow coke pulling.

[0012] Preferably, the feed rate of pure ethylene tar in step S1 is 4-8kg / h. Before starting the oil feed system, the water injection rate of the water injection system is controlled to be 5%-20% of the pure ethylene tar feed rate; after the oil feed in the heating furnace is stable, the water injection rate of the water injection system is controlled to be reduced to 3%-15% of the pure ethylene tar feed rate.

[0013] Preferably, the outlet temperature of the heating furnace in step S2 is 380-480°C.

[0014] Preferably, in step S2, the coking tower feeding time is controlled to be 24-48 hours.

[0015] Preferably, the pressure of the coking tower in step S2 is 0.1-0.7 MPa, and after coking, the coking tower is subjected to insulation treatment at a temperature of 420-505°C.

[0016] Preferably, the airflow coke pulling process in step S2 is divided into two conditions, one of which is a small steam blowing for 1-2 hours, and the water injection rate of the water injection system is controlled to be 3%-10% of the pure ethylene tar feed rate; the other is a large steam blowing for 1.5-4 hours, and the water injection rate of the water injection system is increased to 3%-20% of the pure ethylene tar feed rate, and the pressure is reduced to normal pressure at the same time.

[0017] Preferably, the preparation method further comprises step S3, in which the prepared pre-calcined coke is cleaned out from the coking tower, weighed and calculated, and subjected to decoking analysis, and the pre-calcined coke is respectively subjected to analysis of true density, sulfur, nitrogen, ash, volatile matter, and dry basis moisture.

[0018] Preferably, the preparation method further comprises step S4, in which the pre-calcined coke is calcined at a high temperature according to a procedure.

[0019] The beneficial effects of the present invention are:

[0020] The present invention can solve the problem that the heating furnace coil and the large oil and gas pipeline are very easy to be blocked at present. In the preparation process of producing the pre-calcined coke of the needle coke, pure ethylene tar is used as the raw material, and the optimal pre-calcined coke process parameters of the present invention are strictly controlled by adopting thermogravimetric analysis on the pure ethylene tar. By setting the outlet temperature of the heating furnace to 380-480 DEG C, and performing insulation treatment on the coking tower, the insulation temperature is 420-505 DEG C, the pressure of the coking tower is 0.30Mpa, and small blowing and large blowing operations are performed, the continuous feeding of pure ethylene tar can be realized, the stable production of the system and the continuous production without stopping are improved, and the oil-based needle coke whose ash content, volatile matter, true density, sulfur and nitrogen all meet the pre-calcined coke standards of the oil-based needle coke is prepared, and the by-products coking gasoline, coking diesel and coking wax oil obtained in the preparation process all meet the relevant standards, thereby greatly improving the economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a flow chart of a system and method for preparing needle coke calcined coke from pure ethylene tar of the present invention;

[0023] Figure 2 It is a thermogravimetric analysis data line chart of the system and method for preparing needle coke calcined coke from pure ethylene tar of the present invention;

[0024] In the figure: 1-heating furnace, 2-coking tower, 3-feed pipe, 4-feeding pipe, 5-water injection tank, 6-steam regenerator, 7-transportation pipeline, 8-oil tank, 9-oil feeding pipeline, 10-distillation tower, 1-1-heat exchange tube bundle, 11-flash tower 1, 12-flash tower 2, 13-heavy oil tank, 14-light oil tank 1, 15-light oil tank 2, 16-tail gas treatment device. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] like Figure 1 As shown, a preparation system for producing needle coke calcined coke from pure ethylene tar comprises a heating furnace 1 and a coking tower 2. A heat exchange tube bundle 1-1 is provided in the heating furnace 1. A feed pipe 3 is externally connected to the feed end of the heat exchange tube bundle 1-1. The discharge end is connected to the bottom feed port of the coking tower 2 through a feeding pipe 4. The feed pipe 3 is respectively connected to a water injection system and an oil feeding system. The water injection system comprises a water injection tank 5 and a steam regenerator 6. The water injection tank 5 is connected to the feed end of the steam regenerator 6 through a conveying pipe 7. The discharge end of the steam regenerator 6 is connected to the feed pipe 3. The oil feeding system comprises two oil tanks 8. Each oil tank 8 is connected to the feed pipe 3 through an oil feeding pipe 9. Here, through the design of the steam regenerator 6, the steam dryness and flow rate can be increased, and the preparation efficiency of the entire system can be improved.

[0027] The coking tower 2 is connected to the fractionating tower 10, the flash tower 1 11 and the flash tower 2 12 in sequence through pipelines. A pressure gauge is installed on the connecting pipeline between the coking tower 2 and the fractionating tower 10. The bottom discharge port of the fractionating tower 10 is connected to several heavy oil tanks 13. The flash tower 1 11 and the flash tower 2 12 are interconnected. The bottom discharge port of the flash tower 1 1 is connected to two light oil tanks 14. The bottom discharge port of the flash tower 2 12 is connected to two light oil tanks 2 15. The top gas outlet of the flash tower 2 12 is connected to an exhaust gas treatment device 16. In this embodiment, the exhaust gas treatment device is a flare system. Among them, the gas phase fraction produced in the coking tower passes through the fractionating tower 10, and the heavy fraction is discharged. The fractionating tower 10 is used to separate the hydrogen fraction and the gas product. Here, the flash tower 1 1 and the flash tower 2 12 are common chemical equipment for realizing gas-liquid phase separation of materials in a chemical production process, so the working principle is not repeated.

[0028] On the other hand, the present invention also provides a method for preparing needle coke pre-calcined coke from pure ethylene tar, which is prepared by using the above-mentioned system for preparing needle coke pre-calcined coke from pure ethylene tar. The preparation method comprises the following steps:

[0029] S1. Feed

[0030] The water injection system is turned on, and the softened water in the water injection tank 5 is heat-exchanged into water vapor through the steam regenerator 6 and then transported to the heating furnace 1 through the feed pipe 3;

[0031] Then, the oil inlet system is turned on to transport the pure ethylene tar in the oil tank 8 through the oil delivery pipeline 9 and the feed pipeline 3 to the heating furnace 1;

[0032] The feed rate of pure ethylene tar is 4-8kg / h. Before starting the oil feed system, the water injection rate of the water injection system is controlled to be 5%-20% of the pure ethylene tar feed rate. After the oil feed in the heating furnace 1 is stable, the water injection rate of the water injection system is controlled to be reduced to 3%-15% of the pure ethylene tar feed rate.

[0033] S2. Generation of needle coke before calcination

[0034] The mixed oil and water are heated by a heating furnace 1 and transported to the coking tower 2 from the bottom feed port of the coking tower 2 through a feeding pipe 4. The pure ethylene tar is subjected to thermogravimetric analysis to control the temperature in the coking tower 2 to be 380-480° C. The needle coke calcined coke is formed by the conversion of the carbonaceous mesophase and the coking of the airflow.

[0035] The outlet temperature of the heating furnace 1 is controlled to be 380-480°C, the feeding time of the coking tower 2 is controlled to be 24-48h, the pressure of the coking tower 2 is controlled to be 0.1-0.7Mpa, and after coking, the coking tower 2 is subjected to insulation treatment at a temperature of 420-505°C.

[0036] The process of airflow coke pulling is divided into two conditions, one of which is a small steam blowing for 1-2 hours, and the water injection rate of the water injection system is controlled to be 3%-10% of the pure ethylene tar feed rate; the other is a large steam blowing for 1.5-4 hours, and the water injection rate of the water injection system is increased to 3%-20% of the pure ethylene tar feed rate, and the pressure is reduced to normal pressure at the same time;

[0037] S3, cleaning the prepared pre-calcined coke from the coking tower 2, weighing and calculating, conducting decoking tests, and conducting tests and analyses on the true density, sulfur, nitrogen, ash, volatile matter, and dry basis moisture of the pre-calcined coke;

[0038] S4. calcining the pre-calcined coke at a high temperature according to the procedure.

[0039] The present invention uses pure ethylene tar as raw material and uses thermogravimetric analysis to analyze the pure ethylene tar. Figure 2 As shown, pure ethylene tar has begun to coke at 380°C and is carbonized at 480°C. Therefore, in order to prevent the coil in the heating furnace from being coked and blocked, the outlet temperature of the heating furnace is set to 380-480°C, and the coking tower is insulated at a temperature of 420-505°C. The coking tower pressure is 0.30Mpa, and small and large air blowing operations are performed. Through the preparation method of the present invention, pure ethylene tar can be continuously fed to maintain stable production of the system, and oil-based needle coke whose ash, volatile matter, true density, sulfur and nitrogen all meet the standards of oil-based needle coke before calcination is prepared, and the by-products of coking gasoline, coking diesel and coking wax oil obtained in the preparation process all meet the relevant standards.

[0040] The following is about the application using pure ethylene tar as raw material. Figure 1 Preparation system for producing needle coke from pure ethylene tar:

[0041] The physical and chemical properties of pure ethylene tar raw material oil are as follows:

[0042] Table 1 Physical and chemical properties of ethylene tar

[0043]

[0044] Table 2 Ethylene tar distillation data

[0045]

[0046] Example 1

[0047] A method for preparing needle coke calcined coke from pure ethylene tar is prepared by using the above-mentioned system for preparing needle coke calcined coke from pure ethylene tar. The method comprises the following steps:

[0048] S1. Feed

[0049] The water injection system is turned on, and the softened water in the water injection tank 5 is heat-exchanged into water vapor through the steam regenerator 6 and then transported to the heating furnace 1 through the feed pipe 3;

[0050] Then, the oil inlet system is turned on to transport the pure ethylene tar in the oil tank 8 through the oil delivery pipeline 9 and the feed pipeline 3 to the heating furnace 1;

[0051] Among them, the feed rate of pure ethylene tar is 6kg / h. Before starting the oil inlet system, the water injection rate of the water injection system is controlled to be 960g / h; after the oil inlet in the heating furnace 1 is stable, the water injection rate of the water injection system is controlled to be reduced to 760g / h;

[0052] S2. Generation of needle coke before calcination

[0053] The mixed oil and water are heated by the heating furnace 1, and then transported to the coking tower 2 from the bottom feed port of the coking tower 2 through the feeding pipe 4. The pure ethylene tar is subjected to thermogravimetric analysis, and the outlet temperature of the heating furnace 1 is controlled to be 380-480°C, the temperature in the coking tower 2 is controlled to be 380-480°C, the pressure of the coking tower 2 is maintained at 0.3Mpa, the feeding time is 24h, and the needle coke calcined coke is formed by the conversion of the carbonaceous mesophase and the coking by airflow. The coking tower 2 is subjected to heat preservation treatment, and the heat preservation temperature is 420-505°C;

[0054] Among them, the process of airflow coke pulling is divided into two conditions, one of which is small steam blowing for 2 hours, water injection of 600g / h, large steam blowing for 1.5 hours, increasing water injection to 1200g / h, and using variable pressure operation mode to reduce the pressure to 0.01MPa for decoking. The yield of pre-calcined coke is calculated to be 11.59%, and the total output accounts for 99.13%. Its material balance is shown in Table 5. Sampling and testing, ash, volatile matter, true density, sulfur, nitrogen all meet the standards of oil-based needle coke pre-calcined coke. The results are shown in Table 3. Its by-products coking gasoline, coking diesel and coking wax oil all meet the relevant standards. The specific data are shown in Table 6, Table 7, Table 8. The raw coke is calcined and the physical and chemical indicators of cooked coke are shown in Table 4.

[0055] Table 3 Indices of needle coke before calcination prepared from ethylene tar

[0056]

[0057] Table 4 Index of ripe coke produced from needle coke prepared from ethylene tar

[0058]

[0059] Table 5 Material balance of ethylene tar before calcination

[0060]

[0061]

[0062] Table 6 Coking gasoline product indicators

[0063]

[0064] Table 7 Coking diesel product indicators

[0065]

[0066] Table 8 Wax oil product indicators

[0067]

[0068] Example 2

[0069] A method for preparing needle coke calcined coke from pure ethylene tar is prepared by using the above-mentioned system for preparing needle coke calcined coke from pure ethylene tar. The method comprises the following steps:

[0070] S1. Feed

[0071] The water injection system is turned on, and the softened water in the water injection tank 5 is heat-exchanged into water vapor through the steam regenerator 6 and then transported to the heating furnace 1 through the feed pipe 3;

[0072] Then, the oil inlet system is turned on to transport the pure ethylene tar in the oil tank 8 through the oil delivery pipeline 9 and the feed pipeline 3 to the heating furnace 1;

[0073] Among them, the feed rate of pure ethylene tar is 6kg / h. Before starting the oil inlet system, the water injection rate of the water injection system is controlled to be 960g / h; after the oil inlet in the heating furnace 1 is stable, the water injection rate of the water injection system is controlled to be reduced to 760g / h;

[0074] S2. Generation of needle coke before calcination

[0075] The mixed oil and water are heated by the heating furnace 1, and then transported to the coking tower 2 from the bottom feed port of the coking tower 2 through the feeding pipe 4. The pure ethylene tar is subjected to thermogravimetric analysis, and the outlet temperature of the heating furnace 1 is controlled to be 380-480°C, the temperature in the coking tower 2 is controlled to be 380-480°C, the pressure of the coking tower 2 is maintained at 0.3Mpa, the feeding time is 36h, and the needle coke calcined coke is formed by the conversion of the carbonaceous mesophase and the coking by airflow. The coking tower 2 is subjected to heat preservation treatment, and the heat preservation temperature is 420-505°C;

[0076] Among them, the airflow coke pulling process is divided into two conditions, one of which is small steam blowing for 2 hours, water injection of 600g / h, large steam blowing for 1.5 hours, increasing water injection to 1200g / h, and the total output accounts for 97.17%. Its material balance is shown in Table 11, and sampling and testing, ash, volatile matter, true density, sulfur, nitrogen all meet the standards of oil-based needle coke before calcination, the results are shown in Table 9, and its by-products coking gasoline, coking diesel and coking wax oil all meet the relevant standards, specific data are shown in Table 11, Table 12, Table 13. The raw coke is calcined, and the physical and chemical indicators of cooked coke are shown in Table 10.

[0077] Table 9 Indices of needle coke before calcination prepared from ethylene tar

[0078]

[0079] Table 10 Index of ripe coke in needle coke prepared from ethylene tar

[0080]

[0081] Table 11 Material balance of ethylene tar before calcination

[0082]

[0083] Table 12 Coking gasoline product indicators

[0084]

[0085] Table 13 Coking diesel product indicators

[0086]

[0087] Table 14 Wax oil product indicators

[0088]

[0089] The above disclosures are merely two preferred embodiments of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A system for preparing needle coke calcined coke from pure ethylene tar, characterized in that: The invention comprises a heating furnace (1) and a coking tower (2). A heat exchange tube bundle (1-1) is provided in the heating furnace (1). The feed end of the heat exchange tube bundle (1-1) is externally connected to a feed pipe (3). The discharge end is connected to a bottom feed port of the coking tower (2) via a feeding pipe (4). The feed pipe (3) is respectively connected to a water injection system and an oil supply system. The water injection system comprises at least one water injection tank (5) and a steam regenerator (6). The water injection tank (5) is connected to the feed end of the steam regenerator (6) via a conveying pipe (7). The discharge end of the steam regenerator (6) is connected to the feed pipe (3). The oil supply system comprises at least one oil tank (8). Each of the oil tanks (8) is connected to the feed pipe (3) via an oil supply pipe (9).

2. The system for preparing needle coke calcined coke from pure ethylene tar according to claim 1, characterized in that: The coking tower (2) is connected to a fractionation tower (10), a flash tower 1 (11) and a flash tower 2 (12) in sequence through pipelines; the bottom discharge port of the fractionation tower (10) is connected to a plurality of heavy oil tanks (13); the bottom discharge port of the flash tower 1 (11) is connected to a plurality of light oil tank 1s (14); the bottom discharge port of the flash tower 2 (12) is connected to a plurality of light oil tank 2s (15); and the top gas outlet of the flash tower 2 (12) is connected to an exhaust gas treatment device (16).

3. A method for preparing needle coke calcined coke from pure ethylene tar, characterized in that: The method is prepared by using a system for producing needle coke calcined coke from pure ethylene tar as claimed in any one of claims 1 to 2, wherein the preparation method comprises the following steps: S1. Feed The water injection system is turned on, and the softened water in the water injection tank (5) is heat-exchanged into water vapor through the steam regenerator (6) and then transported to the heating furnace (1) through the feed pipe (3); Then, the oil inlet system is turned on to transport the pure ethylene tar in the oil tank (8) through the oil delivery pipeline (9) and the feed pipeline (3) to the heating furnace (1); S2. Generation of needle coke before calcination The mixed oil and water are heated by a heating furnace (1) and transported to the coking tower (2) from the bottom feed port of the coking tower (2) through a feeding pipe (4). The pure ethylene tar is subjected to thermogravimetric analysis to control the temperature in the coking tower (2) to be 380-480° C. The needle coke pre-calcined coke is formed by the conversion of the carbonaceous intermediate phase and the coking by air flow.

4. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: In step S1, the feed rate of pure ethylene tar is 4-8 kg / h. Before starting the oil feed system, the water injection rate of the water injection system is controlled to be 5%-20% of the pure ethylene tar feed rate. After the oil feed in the heating furnace (1) is stabilized, the water injection rate of the water injection system is controlled to be reduced to 3%-15% of the pure ethylene tar feed rate.

5. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: The outlet temperature of the heating furnace (1) in step S2 is 380-480°C.

6. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: In step S2, the feeding time of the coking tower (2) is controlled to be 24-48 hours.

7. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: In step S2, the pressure of the coking tower (2) is 0.1-0.7 MPa. After coking, the coking tower (2) is subjected to heat preservation treatment at a temperature of 420-505°C.

8. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: The airflow coke pulling process in step S2 is divided into two conditions, one of which is a small steam blowing for 1-2 hours, and the water injection rate of the water injection system is controlled to be 3%-10% of the pure ethylene tar feed rate; the other is a large steam blowing for 1.5-4 hours, and the water injection rate of the water injection system is increased to 3%-20% of the pure ethylene tar feed rate, and the pressure is reduced to normal pressure at the same time.

9. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 3, characterized in that: The preparation method further comprises step S3, in which the prepared pre-calcined coke is cleaned out from the coking tower (2), weighed and calculated, and subjected to decoking analysis, and the pre-calcined coke is subjected to analysis of true density, sulfur, nitrogen, ash, volatile matter, and dry basis moisture.

10. The method for preparing needle coke calcined coke from pure ethylene tar according to claim 9, characterized in that: The preparation method further comprises step S4, in which the pre-calcined coke is calcined at a high temperature according to a procedure.

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