阅读说明：本技术 一种改善针状焦耐压强度的生产工艺 (Production process for improving compressive strength of needle coke ) 是由 亓雁飞 商宝光 许胜军 李兴涛 于 2021-08-31 设计创作，主要内容包括：本发明为一种改善针状焦耐压强度的生产工艺,属于针状焦生产工艺技术领域,其特征在于所述生产工艺包括：原料预处理阶段；大循环升降温阶段、降压升温拉焦阶段和冷却降温阶段,本发明的有益效果是：采用柴油作为拉焦介质代替了传统的蒸汽或惰性气体,避免了废水废气的产生,并且直馏柴油为企业自产,在汽提阶段只进行汽化并未参与反应,且可以冷凝回收利用,真正做到了低成本零污染；本发明创造性的采用柴油作为拉焦介质,大循环升降温生焦工艺和降压升温拉焦的结合,实现了针状焦具有独特的均一性光学性能具有低CTE值的同时具备优越的耐压强度,适合应用于大规格超高功率石墨电极。(The invention relates to a production process for improving the compressive strength of needle coke, which belongs to the technical field of needle coke production processes and is characterized by comprising the following steps: a raw material pretreatment stage; the invention has the beneficial effects that the method comprises a large-cycle temperature rising and falling stage, a pressure and temperature lowering and coke pulling stage and a cooling and temperature lowering stage: the diesel oil is adopted as the coke drawing medium to replace the traditional steam or inert gas, thereby avoiding the generation of waste water and waste gas, and the straight-run diesel oil is produced by enterprises, is vaporized only in the steam stripping stage and does not participate in the reaction, and can be condensed and recycled, thereby really achieving low cost and zero pollution; the invention creatively adopts diesel oil as a coke drawing medium, combines a large-cycle temperature rise and fall coke production process and a pressure reduction temperature rise coke drawing process, realizes that needle coke has unique uniform optical performance, has a low CTE value and excellent compressive strength, and is suitable for being applied to large-scale ultrahigh-power graphite electrodes.)

1. A production process for improving the compressive strength of needle coke is characterized by comprising the following steps:

firstly, a raw material pretreatment stage:

adding the catalytic slurry oil coking raw material subjected to vacuum fractionation, extraction and hydrodesulfurization pretreatment into a raw oil tank;

a large-cycle temperature rise and fall stage:

step three, pressure reduction and temperature rise coke pulling stage:

cooling:

and after the steam stripping is finished, reducing the temperature of each heating point, and reducing the temperature and the pressure of the device.

2. The production process for improving the compressive strength of needle coke according to claim 1, wherein the coke-drawing medium is diesel oil, and a small amount of nitrogen is fed to push the diesel oil to flow in the furnace tube.

3. The process for producing needle coke with improved compressive strength according to claim 2, wherein the temperature raising and lowering phase of the large cycle comprises:

preheating the circulating oil at 450 ℃ by a heating furnace according to the circulation ratio of (3-5):1, then feeding the oil into a coke tower, gradually heating the coke tower to 480-: 1, the mixture is uniformly mixed in two paths in front of a heating furnace and enters a coke tower, the temperature of the coke tower is quickly adjusted to 430-470 ℃, and the pressure is maintained at 8-15kg/cm²And starting to generate coke for 24 h.

4. The production process for improving the compressive strength of needle coke according to claim 1, wherein the step of reducing and raising the temperature and the coke drawing stage comprises:

after the feeding is stopped, the temperature of the heating furnace and the coke tower is increased, the coke drawing medium is fed for coke drawing, and the decompression rate is 2kg/cm²H, gradually reducing the pressure of the coke tower to 6kg/cm²Raising the temperature of the coke tower to 490-510 ℃ at a temperature raising speed of 15 ℃/h; stopping feeding, starting to feed the coke-drawing medium to draw coke, and carrying out coke-drawing for 24 hours.

5. The process according to claim 3, wherein the amount of said cycle oil is 1.5kg/cm of raw oil for coking²And the distillate oil of the coke tower at 430-480 ℃ is light wax oil.

The technical field is as follows:

the invention belongs to the technical field of needle coke production processes, and particularly relates to a production process for improving the compressive strength of needle coke.

Background art:

needle coke, as a novel carbon material, has the characteristics of strong thermal shock resistance, high mechanical strength, good oxidation performance, less electrode consumption and the like, is a high-quality raw material for producing high-power and ultrahigh-power graphite electrodes, and the performance of the needle coke determines the properties of the ultrahigh-power graphite electrodes.

The needle coke has metallic luster in appearance, layered structure inside, good orientation and good electric and heat conductivity. The main application fields at present are ultra-high power electrodes and battery negative electrode materials. The mechanical strength is one of the most important indexes of the needle coke, and has important significance.

The needle coke is subjected to processes of kneading, extrusion forming and the like in the process of producing the ultrahigh-power graphite electrode, in the process, part of the needle coke is crushed to cause the characteristics of poor mechanical strength, high resistance, low oxidation resistance and the like of the ultrahigh-power graphite electrode, and the mechanical strength of the needle coke is generally expressed by compressive strength.

At present, a delayed coking process is mostly adopted for producing needle coke, the delayed coking process is mostly divided into two stages, coke is formed by feeding and is removed by blowing steam, steam is adopted as a medium in the traditional process, the coke is removed after 3-4 hours of steam blowing, and waste water generated by steam blowing is difficult to treat, so that the environmental protection pressure is higher.

In particular, needle coke prepared by adopting a traditional process with gas as a medium generally has the characteristic of nonuniform upper and lower parts of the needle coke, the upper sample and the middle sample are superior to the lower sample and correspond to CTE (coefficient of thermal expansion), and the key factor of pursuing the low CTE value of the needle coke on the sheet surface is often ignored, so that the CTE value of the needle coke is lower, but the compressive strength is not high, the mechanical strength is low, and the needle coke is not suitable for being applied to large-specification ultrahigh-power graphite electrodes.

The invention content is as follows:

in order to solve the problems and overcome the defects of the prior art, the invention provides the needle coke which has unique uniform optical performance, low CTE value and excellent compressive strength and is suitable for being applied to large-scale ultrahigh-power graphite electrodes.

The specific technical scheme for solving the technical problems comprises the following steps: the production process for improving the compressive strength of the needle coke is characterized by comprising the following steps:

firstly, a raw material pretreatment stage:

adding the catalytic slurry oil coking raw material subjected to vacuum fractionation, extraction and hydrodesulfurization pretreatment into a raw oil tank;

a large-cycle temperature rise and fall stage:

preheating the circulating oil at 450 ℃ by a heating furnace according to the circulation ratio of (3-5):1, then feeding the oil into a coke tower, gradually heating the coke tower to 480-: 1, the mixture is uniformly mixed in two paths in front of a heating furnace and enters a coke tower, the temperature of the coke tower is quickly adjusted to 430-470 ℃, and the pressure is maintained at 8-15kg/cm²Starting coke generation for 24 hours;

step three, pressure reduction and temperature rise coke pulling stage:

after the feeding is stopped, the temperature of the heating furnace and the coke tower is increased, the coke drawing medium is fed for coke drawing, and the decompression rate is 2kg/cm²H, gradually reducing the pressure of the coke tower to 6kg/cm²Raising the temperature of the coke tower to 490-510 ℃ at a temperature raising speed of 15 ℃/h; stopping feeding, starting to feed the coke-drawing medium to draw coke, and carrying out coke-drawing for 24 hours.

Cooling:

and after the steam stripping is finished, reducing the temperature of each heating point, and reducing the temperature and the pressure of the device.

The circulating oil is coked raw oil at 1.5kg/cm²And the distillate oil of the coke tower at 430-480 ℃ is light wax oil.

The coke-drawing medium adopts diesel oil, and a small amount of nitrogen is fed to push the diesel oil to flow in the furnace tube.

The invention has the beneficial effects that:

the diesel oil is adopted as the coke drawing medium to replace the traditional steam or inert gas, thereby avoiding the generation of waste water and waste gas, and the straight-run diesel oil is produced by enterprises, is vaporized only in the steam stripping stage and does not participate in the reaction, and can be condensed and recycled, thereby really achieving low cost and zero pollution;

the invention creatively adopts diesel oil as the coke drawing medium, avoids the generation of waste water and waste gas, achieves low cost and zero pollution, and simultaneously unexpectedly discovers that the needle coke prepared by the method has unique uniform optical performance and low CTE value;

the invention creatively adopts diesel oil as a coke drawing medium, combines a large-cycle temperature rise and fall coke production process and a pressure reduction temperature rise coke drawing process, realizes that needle coke has unique uniform optical performance, has a low CTE value and excellent compressive strength, and is suitable for being applied to large-scale ultrahigh-power graphite electrodes.

Description of the drawings:

FIG. 1 is a schematic diagram of an optical image and CTE curve of a needle coke produced according to the present invention;

FIG. 2 is a graph showing an optical image and a CTE curve of a needle coke prepared in comparative example III;

FIG. 3 is a graph showing an optical picture and CTE curve for a needle coke prepared in comparative example four;

FIG. 4 is a graph showing an optical picture and CTE curve for needle coke prepared in comparative example V; in the drawings:

the specific implementation mode is as follows:

in the description of the invention, specific details are given only to enable a full understanding of the embodiments of the invention, but it should be understood by those skilled in the art that the invention is not limited to these details for the implementation. In other instances, well-known structures and functions have not been described or shown in detail to avoid obscuring the points of the embodiments of the invention. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The specific implementation mode of the invention is as follows: in order to more intuitively show the advantages of the diesel oil coke-drawing process, the production process for improving the compressive strength of the needle coke is compared with the same process by adopting an equivalent replacement method,

comparative example one:

the preparation method is the same as the invention, except that: in the preparation process of the comparative example, the coke-drawing medium in the coke-drawing process is replaced by diesel oil into steam;

comparative example two:

the preparation method is the same as the invention, except that: in the preparation process of the comparative example, the coke-drawing medium in the coke-drawing process is replaced by the nitrogen gas from the diesel oil;

table 1: different coke-drawing medium waste gas and waste liquid and cost comparison data

	Coke drawing medium	Exhaust gas	Waste liquid	Cost of
					Example two	Diesel oil	Chinese character shao (a Chinese character of 'shao')	Is free of	Is lower than
Comparative example 1	Steam of water	Chinese character shao (a Chinese character of 'shao')	Multiple purpose	In
					Comparative example No. two	Nitrogen gas	Multiple purpose	Is free of	Height of

The above table data analysis shows that: the diesel oil is used as a coking medium to replace the traditional steam or inert gas, so that the generation of waste water and waste gas is avoided, the straight-run diesel oil is produced by enterprises, only vaporization is carried out in a stripping stage, the reaction is not participated, and the diesel oil can be condensed and recycled, so that the low cost and zero pollution are really realized.

In order to more intuitively show the technological advantages of the optical performance and the compressive strength of the needle coke, the production technology for improving the compressive strength of the needle coke is compared with the same technology by adopting an equivalent replacement method,

comparative example three:

the preparation method is the same as the invention, except that: in the preparation process of the comparative example, the coke forming process in the large-circulation temperature rise and fall stage is replaced by a constant-temperature coke forming process with a low circulation ratio: namely, it is

The raw oil and the circulating oil are divided into two paths according to a preset circulation ratio and are uniformly mixed in front of a heating furnace, the preset circulation ratio is 1.2, the raw oil and the circulating oil enter a coke tower through preheating of the heating furnace to react for coke formation, and the conditions of the coke formation process are that the temperature of the coke tower is controlled to be 400-550 ℃, and the pressure is controlled to be 5-15kg/cm²；

Comparative example four:

the preparation method is the same as the invention, except that: in the preparation process of the comparative example, the coke-drawing process in the pressure-reducing and temperature-raising coke-drawing stage is replaced by pressure-reducing and constant-temperature coke-drawing:

the coke drawing medium adopts diesel oil, a small amount of nitrogen is fed to push the diesel oil to flow in the furnace tube, the coke drawing temperature is controlled at 420-600 ℃, pressure reduction operation is adopted, and the pressure of a coke tower is controlled from 5-15kg/cm²Uniformly reducing the concentration to 4-12kg/cm²The coke-pulling period is 12 hours;

comparative example five:

the preparation method is the same as the invention, except that: in the preparation process of the comparative example, the coke forming process in the large-circulation temperature rise and fall stage is replaced by a constant-temperature coke forming process with a low circulation ratio: namely, it is

The raw oil and the circulating oil are divided into two paths according to a preset circulating ratio and are uniformly mixed in front of a heating furnace for circulationThe ratio is 1.2, the coke enters a coke tower through the preheating of a heating furnace to react for coke formation, and the conditions of the coke tower temperature is controlled to be 400-550 ℃, and the pressure is controlled to be 5-15kg/cm²；

And the coke-pulling process in the pressure-reducing and temperature-raising coke-pulling stage is replaced by pressure-reducing and constant-temperature coke-pulling:

the coke drawing medium adopts diesel oil, a small amount of nitrogen is fed to push the diesel oil to flow in the furnace tube, the coke drawing temperature is controlled at 420-600 ℃, pressure reduction operation is adopted, and the pressure of a coke tower is controlled from 5-15kg/cm²Uniformly reducing the concentration to 4-12kg/cm²The coke-pulling period is 12 hours;

table 2: comparison of data for optical Properties and compressive Strength under different Process conditions

From the data in Table 2, and with reference to the optical images and CTE curves of FIG. 1, it can be seen that: the needle coke prepared by the method has good fiber structures in the upper sample, the middle sample and the lower sample, the fiber orientations are consistent, the compressive strength and the CTE are tested, the CTE values are less than 1.1, the requirements of ultrahigh power graphite electrodes are met, and the compressive strength is higher than 37.

From the data in Table 2, and with reference to the optical pictures and CTE curves of FIG. 2, it can be seen that:

the needle coke prepared in the third comparative example shows disordered optical performance in the loading sample, the middle sample and the unloading sample, the mesophase shows inconsistent performance, and the compressive strength and the CTE test are carried out, wherein the CTE of the three samples is higher than 1.3, and the compressive strength is higher than 30.

From the data in Table 2, and with reference to the optical pictures and CTE curves of FIG. 3, it can be seen that:

the needle coke prepared in comparative example four has a good fiber structure in the loading and middle samples, but the fibers in the loading and middle samples are scattered and have different fiber orientations, and the compression strength and CTE tests are carried out, wherein the CTE of the loading and middle samples is lower than 1.1, the CTE of the loading and middle samples is 1.39, and the compression strength of the loading and middle samples is lower than 30.

From the data in Table 2, and with reference to the optical pictures and CTE curves of FIG. 4, it can be seen that:

the needle coke prepared by the fifth comparative example has uniform upper sample, middle sample and lower sample, small difference, obvious mesophase structure, fiber extending towards one direction, uniform mesophase structure, compressive strength and CTE test, wherein the CTE of the upper sample, the CTE of the middle sample and the CTE of the lower sample are all lower than 1.1, but the compressive strength of the upper sample, the CTE of the middle sample and the compressive strength of the lower sample are all lower than 30.

In summary, the following steps: the diesel oil is adopted as the coke drawing medium to replace the traditional steam or inert gas, thereby avoiding the generation of waste water and waste gas, and the straight-run diesel oil is produced by enterprises, is vaporized only in the steam stripping stage and does not participate in the reaction, and can be condensed and recycled, thereby really achieving low cost and zero pollution;

the invention creatively adopts diesel oil as the coke drawing medium, avoids the generation of waste water and waste gas, achieves low cost and zero pollution, and simultaneously unexpectedly discovers that the needle coke prepared by the method has unique uniform optical performance and low CTE value;

the invention creatively adopts diesel oil as a coke drawing medium, combines a large-cycle temperature rise and fall coke production process and a pressure reduction temperature rise coke drawing process, realizes that needle coke has unique uniform optical performance, has a low CTE value and excellent compressive strength, and is suitable for being applied to large-scale ultrahigh-power graphite electrodes.