JPH02145688A - Production of needle coke - Google Patents

Abstract

PURPOSE:To obtain needle coke containing reduced puffing by slowly calcining raw coke with controlling temperature rising rate and quickly rising temperature without cooling. CONSTITUTION:Raw needle coke obtained by delayed coking of carbonaceous raw material at 450-500 deg.C is slowly heated with <=20 deg.C/min average heating speed, calcined at 500-900 deg.C and successively quickly heated from said calcining temperature to 1200-1500 deg.C of final calcining temperature with 25-200 deg.C/min average heating speed without cooling to afford calcined needle coke.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing needle coke, and more particularly to a method for improving the calcination method and reducing buffing.

(Prior art) Needle coke is generally produced by using raw coke containing 5 to 12% volatile matter and a calcining furnace such as a rotary kiln to remove volatile matter and increase the carbonization degree to 1100 to 150%.
Manufactured by calcination in a temperature range of 0°C.

However, there are not many proposals to successfully utilize this calcination process to obtain low-puffing needle coke. Two-stage calcination (Japanese Patent Publication No. 14111/1986), long-time calcination (
JP-A-58-183789) and high-temperature calcination (JP-A-60-208392).

(Problems to be Solved by the Invention) However, most of the above proposals do not bring about significant effects in terms of economy and quality.

For example, calcination in an oxidizing gas atmosphere is intended to burn coke and increase the number of holes to suppress buffing, and the calcination yield drops significantly.

Prolonged calcination is undesirable as it reduces production. In addition, high-temperature calcination (Japanese Patent Laid-Open No. 60-208392
Although the buffing is reduced, the "wetting" with the binder pitch becomes poor and the density becomes low, which is not suitable for the purpose of eliminating buffing.

Two-stage calcination reduces grain strength, generates a large amount of powder, and is difficult to be economical because it requires calcination twice.

[Means to solve the problem]

Therefore, in view of the above-mentioned circumstances, the inventors of the present invention have determined that it is necessary to find a further improved method.
We have found and completed a calcination method that can reduce buffing by slowly calcination at 00 to 900°C and then rapidly raising the temperature without cooling.

For details, see the temperature increase rate of 25℃ when calcining raw coke.
/min or more to reduce buffing by creating fine cracks in the calcined coke, but this operation causes the volatile matter in the raw coke to turn into coke around the coke, and heat The disadvantage is that the expansion coefficient deteriorates. Therefore, raw coke is exposed to a temperature of 500 to 900 degrees Celsius by slowly raising the temperature in advance.
Remove the volatile matter in the raw coke and then heat at 25°C/min.
The purpose is to raise the temperature to the final calcination temperature at the above rate and obtain coke with low buffing without deteriorating the coefficient of thermal expansion.

That is, the gist of the present invention is that when calcining raw needle coke obtained by delayed loking of carbonaceous raw materials at 450 to 500 °C,
500℃ by increasing the temperature at an average rate of 0℃/min or less
The method of producing needle coke includes calcination at ~900°C, and then raising the temperature from the calcination temperature to a final calcination temperature of 1,200 to 1,500°C for 25~b without cooling.

The present invention will be explained in detail below.

The carbonaceous raw materials used in the method of the present invention refer to heavy oils known as ordinary delayed coker feedstocks such as coal cool, coal tar pitch, vacuum distillation residue oil, fluid catalytic cracking oil, and thermal cracking residue oil. do. Further, the coking conditions in the present invention are not particularly limited, and a normal delayed caulking method may be used. Raw coke is obtained by cutting coke from a coke drum using high-pressure water, or it has a certain particle size structure that has been broken during transportation or broken by a crusher or the like.

This raw coke is heated to 1200 to 1500°C in a calcining furnace such as a rotary kiln to remove volatile matter and increase the degree of carbonization.
It is calcined in the final temperature range of 20℃/mi during this period.
Raise the temperature at an average rate of n3 or less, preferably 5 °C/min or less, and reduce the volatile content to 2% at a temperature within the range of 500 to 900 °C.
Thereafter, it is preferably calcined for a time to substantially 0%. 5
At temperatures below 00°C, removal of volatile matter is impossible, and at temperatures above 900°C, buffing is insufficiently reduced.

Next, without cooling once, heating is continued to a calcination temperature of 1,200 to 1,500°C at a heating rate of 25°C/min or more, but if the heating rate is increased too much, the grain strength of the coke produced will decrease. Temperature rate is 25℃/min-10
Selected from 0''C/min, preferably 30~50℃
/min. Examples of methods for maintaining this temperature increase rate include a method of increasing the rotational speed of a rotary kiln, a method of installing two rotary kilns, and the like.

The atmosphere for the above-mentioned calcination is not particularly limited, but an inert atmosphere is preferable.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the Examples described later.

Example 1 Coal tar pitch with 0% quinoline solubility at 480°C
A raw needle coke with a volatile content of 6% was obtained by delayed loking. The coke was calcined at 700°C for 1 hour in an inert atmosphere at a heating temperature of 4°C/min, and then heated to 1300°C at a heating rate of 30'C/min to obtain calcined coke.

This calcined needle coke was crushed and sieved, the particle size was appropriately mixed, and 32 parts of binder pitch was added to 100 parts of this coke.

After mixing, extrusion molding is performed to form 25Mφ x 12Omm.
Make the last piece of L and bake it at 1000℃ and then heat it to 20℃/
The temperature was raised to 2800°C at a heating rate of 'min' and held for 30 minutes. Buffing was calculated by measuring the diameter before and after graphitization. Furthermore, the test piece after graphitization was 20a.
Cut to nφ x 100 and use this to heat at 25 to 125℃
The coefficient of thermal expansion between As a result, the coefficient of thermal expansion is 3
X 10-'/''C, buffing was 1.0%.

Comparative Example 1 In Example 1, raw coke was heated at a rate of 4° C./min and calcined at 1300° C., and the same evaluation as in Example 1 was performed.

Coefficient of thermal expansion 3. OX 10-'/''C buffing was 2.0%.

Comparative Example 2 In Example 1, the heating rate of raw coke was 30"C/m.
The temperature was raised all at once at a rate of in and calcined at 1300°C.

The same evaluation as in Example 1 was performed.

Thermal expansion coefficient was 5 x 10-'/'C buffing 1.0%.

[Effects of the Invention] The present invention can achieve low buffing by a very simple method of controlling the temperature increase rate during calcination, and the effect is extremely large.

Claims (1)

[Claims] (1) When calcining raw needle coke obtained by delayed loking of carbonaceous raw materials at 450 to 500°C, the temperature is raised at an average rate of 20°C/min or less to 500°C.
It is characterized by calcination at ~900°C, and then increasing the temperature from the calcination temperature to the final calcination temperature of 1,200 to 1,500°C at an average rate of 25 to 200°C/min without cooling. A method for producing needle coke.