A method for producing needle coke for a joint

Abstract

This invention relates to the field of needle coke production technology, and particularly to a method for producing needle coke for connectors. The method comprises the following steps: Step 1: Distilling and fractionating the oil used as needle coke feedstock to obtain an oil fraction with a tetracyclic aromatic hydrocarbon content of 30% or higher; blending this oil with the original needle coke feedstock; Step 2: Producing needle coke using the feedstock from Step 1, injecting water at a ratio of 5%-25% of the feed amount for coking operation 2-10 hours before the end of the delayed coking process; Step 3: Continuing water injection for 6-36 hours after the delayed coking process in Step 2 to perform coke drying operation; Step 4: Removing coke after coke drying to obtain the needle coke product. This invention achieves higher quality needle coke products, reaching the level of needle coke for connectors, without changing the source of the raw materials, by extracting key components from the raw materials themselves to strengthen and improve the raw materials, and by combining appropriate coking and coke drying processes.

Description

Technical fields:

[0001] This invention relates to the field of needle coke production technology, and in particular to a method for producing needle coke for connectors. Background technology:

[0002] Needle coke, a type of high-quality petroleum coke, possesses a series of advantages, including a low coefficient of thermal expansion, low porosity, low sulfur content, low ash content, low metal content, high electrical conductivity, and ease of graphitization. Needle coke production is generally based on a delayed coking process, requiring the selection of suitable raw materials, as not all high-aromatic feedstocks can be successfully converted into needle coke. The main industrial sources of raw materials for needle coke production include: catalytic cracking clarified oil (FCCDO), naphtha, and ethylene tar (ET) obtained from the steam cracking of crude diesel to produce ethylene, cracking tar (TR) from thermal cracking, and coal tar (CR) produced from coal coking or gasification. Needle coke is a primary raw material for producing high-power and ultra-high-power graphite electrodes. Whether oil-based or coal-based needle coke, the production process consists of three parts: raw material pretreatment, delayed coking, and calcination.

[0003] Graphite electrodes consist of two parts: the electrode body and the electrode connector. Depending on the power and current used, graphite electrodes can be classified into ordinary power graphite electrodes, high-power graphite electrodes, and ultra-high-power graphite electrodes. They primarily use petroleum coke and needle coke as raw materials. The key parameters, raw materials, and application fields differ for graphite electrodes of different power ratings. The requirements for needle coke used in the connector are the highest; the standard for connector coke is a calcined needle coke CTE ≤ 1.0 and a true density ≥ 2.14 g / cm³. 3 Tap density ≥ 1.0 g / cm³ 3 However, the general needle coke production process cannot meet the above requirements.

[0004] Existing solutions for improving the quality of needle coke mainly include two aspects:

[0005] 1. Improve feedstock. Existing solutions for expanding needle coke feedstock include two main approaches: One involves pretreatment, such as hydrogenation and extraction. These methods require the introduction of external streams like hydrogenation catalysts, hydrogen, and extraction solvents, and necessitate equipment such as hydrogenation reactors, extraction towers, and solvent recovery towers, resulting in high pretreatment costs. Another approach involves introducing other oil products besides catalytic cracking slurry, such as ethylene tar and vacuum residue. However, due to the complex composition of these feedstocks, their impact on needle coke quality is difficult to predict, and they cannot guarantee compliance with standards for needle coke used in joints.

[0006] 2. Improve the process. Existing needle coke usually adopts the coke pulling process, but most steam coke pulling processes do not set optimal process conditions for the timing and duration of intervention.

[0007] Given that existing needle coke products are unable to meet the standards for needle coke used in connectors, there is an urgent need to provide a feasible process method that can produce needle coke products that meet the standards for needle coke used in connectors. Summary of the Invention:

[0008] The technical problem to be solved by the present invention is to provide a method for producing needle coke for connectors. This method achieves the goal of improving the raw materials by cutting out key components from the raw materials themselves without changing the source of the raw materials, and then combining it with appropriate coking and drying processes to obtain higher quality needle coke products, reaching the level of needle coke for connectors.

[0009] The technical solution adopted in this invention is: a method for producing needle coke for connectors, the steps of which are as follows:

[0010] Step 1: Distill the oil used as needle coke feedstock to obtain oil fractions with a tetracyclic aromatic hydrocarbon content of more than 30%; blend this oil with the original needle coke feedstock in a ratio of 1:9 to 5:5.

[0011] Step 2: Using the raw materials mixed in Step 1 to produce needle coke, water is injected at a ratio of 5%-25% of the feed amount 2-10 hours before the end of the delayed coking process to carry out the coke pulling operation.

[0012] Step 3: After the delayed coking process in Step 2 is completed, continue to inject water for 6-36 hours to carry out the coking operation;

[0013] Step 4: After the coking process is completed, remove the coke to obtain needle coke product.

[0014] Furthermore, in step one, the distillation fraction cutting temperature is selected as 420℃-460℃.

[0015] Furthermore, in step one, the mixing ratio is preferably 20%-40%.

[0016] Furthermore, in step two, water is injected 4-8 hours before the end of the delayed coking process to perform a coke pulling operation.

[0017] Furthermore, in step two, water is injected at a ratio of 10%-25% of the feed amount to perform the coking operation.

[0018] Furthermore, in step three, the continuous water injection is preferably carried out for 8-24 hours.

[0019] The beneficial effects of this invention are:

[0020] 1. Cutting needle coke raw materials into product components at key temperature ranges and then adding them back into the raw materials can improve the raw materials and enhance product quality.

[0021] 2. By adopting appropriate coking and drying processes based on the improved raw materials, product quality can be further improved and needle coke for joints can be obtained. Detailed implementation method:

[0022] Example 1

[0023] A certain raw material is used to produce needle coke using a delayed coking process. The coke is then distilled and fractionated to obtain an oil product with a tetracyclic aromatic hydrocarbon content of over 30% in the 420℃ to 500℃ fraction. This oil product is blended with the original needle coke feedstock at a ratio of 1:9. Two hours before the end of the delayed coking process, water is injected at a rate of 5% of the feed volume to induce coke pulling. After the delayed coking process is completed, water injection continues for 6 hours to induce coke drying.

[0024] The CTE of the calcined needle coke was 0.95, and its true density was 2.141 g / cm³. 3 The tap density is 1.02 g / cm³. 3 .

[0025] Example 2

[0026] A certain raw material is processed using a delayed coking process to produce needle coke. The resulting distillate fraction, obtained at temperatures between 420°C and 500°C, contains over 30% tetracyclic aromatic hydrocarbons. This oil is then blended with the original needle coke feedstock at a ratio of 2:8. Four hours before the end of the delayed coking process, water is injected at a rate of 10% of the feed volume to induce coke pulling. After the delayed coking process is completed, water injection continues for 12 hours to induce coke drying.

[0027] The CTE of the calcined needle coke was 0.90, and its true density was 2.143 g / cm³. 3 The tap density is 1.03 g / cm³. 3 .

[0028] Example 3

[0029] Needle coke is produced from a certain raw material using a delayed coking process. The distillation fraction is then cut to obtain an oil product with a tetracyclic aromatic hydrocarbon content of over 30% in the 420℃ to 500℃ fraction. This oil product is blended with the original needle coke feedstock at a ratio of 3:7. Four hours before the end of the delayed coking process, water is injected at a rate of 15% of the feed volume to initiate a coke pulling operation. After the delayed coking process is completed, water injection continues for 18 hours to perform a coke drying operation.

[0030] The CTE of the calcined needle coke was 0.92, and its true density was 2.145 g / cm³. 3 The tap density is 1.05 g / cm³. 3 .

[0031] Example 4

[0032] Needle coke is produced from a certain raw material using a delayed coking process. The resulting distillate fraction, at a temperature between 420°C and 460°C, yields an oil product with a tetracyclic aromatic hydrocarbon content exceeding 30%. This oil product is then blended with the original needle coke feedstock at a ratio of 3:7. Six hours before the end of the delayed coking process, water is injected at a rate of 20% of the feed volume to induce coke pulling. After the delayed coking process concludes, water injection continues for 24 hours to induce coke drying.

[0033] The CTE of the calcined needle coke was 0.89, and its true density was 2.150 g / cm³. 3 The tap density is 1.08 g / cm³. 3 .

[0034] Example 5

[0035] Needle coke is produced from a certain raw material using a delayed coking process. The distillation fraction is then cut to obtain an oil product with a tetracyclic aromatic hydrocarbon content of over 30% in the 420℃ to 500℃ fraction. This oil product is blended with the original needle coke feedstock at a ratio of 5:5. Six hours before the end of the delayed coking process, water is injected at a rate of 25% of the feed volume to initiate a coke pulling operation. After the delayed coking process is completed, water injection continues for 36 hours to perform a coke drying operation.

[0036] The CTE of the calcined needle coke was 0.98, and its true density was 2.142 g / cm³. 3 The tap density is 1.01 g / cm³. 3 .

[0037] Comparative Example 1

[0038] A certain raw material was used to produce needle coke using a delayed coking process. The calcined needle coke product had a CTE of 1.25 and a true density of 2.137 g / cm³. 3 The tap density is 0.87 g / cm³. 3 .

[0039] As shown in Examples 1-5 and Comparative Example 1, the embodiments of the present invention, without changing the source of raw materials, rely on the raw materials themselves to cut out key components to strengthen and improve the raw materials, and then combine with appropriate coking and drying processes to obtain higher quality needle coke products, reaching the level of needle coke for connectors.

[0040] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A method for producing needle coke for connectors, characterized in that: The steps of this method are as follows: Step 1: Distill the oil used as needle coke feedstock to obtain oil fractions with a tetracyclic aromatic hydrocarbon content of more than 30%; blend this oil with the original needle coke feedstock in a ratio of 1:9 to 5:

5. Step 2: Using the raw materials mixed in Step 1 to produce needle coke, water is injected at a ratio of 5%-25% of the feed amount 2-10 hours before the end of the delayed coking process to carry out the coke pulling operation. Step 3: After the delayed coking process in Step 2 is completed, continue to inject water for 6-36 hours to carry out the coking operation; Step 4: After the coking process is completed, remove the coke to obtain needle coke product.

2. The method for producing needle coke for connectors according to claim 1, characterized in that: In step one, the distillation fraction cutting temperature is selected as 420℃-460℃.

3. The method for producing needle coke for connectors according to claim 1, characterized in that: In step one, the preferred mixing ratio is 20%-40%.

4. The method for producing needle coke for connectors according to claim 1, characterized in that: In step two, water is injected 4-8 hours before the end of the delayed coking process to perform coke pulling.

5. The method for producing needle coke for connectors according to claim 1, characterized in that: In step two, water is injected at a ratio of 10%-25% of the feed amount to perform the coking operation.

6. The method for producing needle coke for connectors according to claim 1, characterized in that: In step three, the water injection is preferably carried out for 8-24 hours.