JP2538563B2 - High-quality coke manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing high-quality coke, and more particularly to a method for producing high-quality needle coke having a low coefficient of thermal expansion.

(Prior Art) In recent years, artificial and graphite electrodes are required to have high mechanical strength and excellent thermal shock resistance as the electrode usage conditions become severer. Pitches and the like are required to manufacture such artificial graphite electrodes. Basically, it is necessary to use high-quality needle coke with a small coefficient of thermal expansion as an aggregate, not to mention the idea of the binder surface. In order to produce such a high-quality coke, many proposals have already been made regarding selection of raw material heavy oil, coking conditions, calcination conditions, etc. Among them, there are raw coke after coking or after coking. It is known that the volatile content in coke is one of the important factors, and various attempts to control it have been proposed. For example, the lower the volatile content of the raw coke to be subjected to the calcination step, the smaller the coefficient of thermal expansion of the product coke obtained after the calcination tends to be. Therefore, the volatile content of the raw coke remains constant. Efforts are underway to maintain below value.

(Problems to be solved by the invention) However, this tendency is not perfect, and a good product may be obtained even at a high volatile content close to 10 wt%.
Since a sufficient level of product cannot be obtained even at a low level of about 5 wt%, an index for more stable production of high-quality coke is desired.

(Means for Solving Problems) Then, in view of the above-mentioned circumstances, the present inventors have made diligent studies to find out a better index, and as a result, most of the conventional proposals are about the type of raw material heavy oil and caulking conditions. It was recognized that calcination was merely a process for removing volatile matter and did not significantly affect the quality of coke, but unexpectedly, the volatile matter content of the raw coke supplied to this calcination process was We have found that the thermal expansion characteristics of a graphite product can be stably improved by adjusting the particle size according to the requirements, and have completed the present invention.

That is, the gist of the present invention is that when raw coke having a volatile content of about 4 to 10 wt% obtained by laying a carbonaceous raw material is calcined, the volatile content (VM) of the raw coke is According to the following selection conditions, the raw coke from which the fine powder portion has been removed is calcined, and a method for producing high-quality coke is provided.

When VM <5wt%, the particle size is at least 0.8mm,
Fine particles with a diameter of 1.7 mm or less preferably 5 wt% ≤ VM ≤ 7 wt%
Fine particles of m or less, preferably 3.4 mm or less When VM> 7 wt%, at least the particle size is 3.4 mm or less,
The present invention will be described in detail below, preferably with a fine grain portion of 6.7 mm or less.

The carbonaceous raw material used in the method of the present invention is a heavy oil known as a usual delayed coker raw material oil such as coal tar, coal tar pitch, vacuum distillation residual oil, fluid catalytic cracking oil, and thermal cracking residual oil. Is called.

In addition, the coking conditions in the present invention are not particularly limited, and a usual delayed coking method may be used, but the temperature is preferably about 450 to 500 ° C. to obtain the raw coke to be treated in the present invention. Raw coke is obtained by cutting it out of a coke drum with high-pressure water, but it is normally destroyed during transfer or by flasher, and has a certain particle size composition.

Raw coke having such a particle size constitution and having a volatile content (hereinafter abbreviated as VM) of about 4 wt% or more and about 10 wt% or less is treated by the present invention. Generally, the delayed coking with VM of 4 wt% or less is not practical because it requires considerably severe operating conditions, but in some cases, the VM of up to 3 wt% may be used. Includes. On the other hand, if delayed coking is performed under mild operating conditions, it is possible to produce raw coke with a high VM of, for example, 15 wt% or more. However, such raw coke will be high no matter how calcination conditions are devised. It is difficult to make quality coke. However, the allowable range varies depending on the case and cannot be specified unconditionally, but it is usually around 11 to 12 wt%, and the present invention thus includes the range in which high quality coke can be produced by selecting the calcination conditions.

In the present invention, when calcining the raw coke having the VM value as described above, in case of VM <5 wt%, the particle size is 0.8 mm or less, more preferably 1.7 mm or less, the fine particle portion is VM
When ≦ 7wt%, the particle size is 1.7mm or less, more preferably 3.4m
Fine particles of m or less, or particle diameter of 3.4 mm when c VM> 7 wt%
Hereinafter, more preferably, the fine particle portion having a size of 6.7 mm or less is substantially removed. Of course, for some purpose, a particle size portion having a particle size equal to or larger than the particle size specified in the above selection conditions may be partially removed together with such a fine particle portion, but in the present invention, at least the above fine particle portion is substantially removed. Is desired. However, in the present invention, the particle size values under the above selection conditions a, b, and c should be understood as target values. For example, even if only the fine particle portions that are 10 to 20% lower than the particle size values are removed, the thermal expansion will be as such. In order to improve the characteristics, it is important to remove the fine particle portion corresponding to the target value as described above according to the VM of the raw coke.

The raw coke having the grain size adjusted as described above is then calcined, but the calcining operation can be carried out by a conventional method, for example, 1300 ~ using a calcining furnace such as a rotary kiln, a shaft furnace, or a rotary hearth furnace. It may be calcined at a temperature of about 1500 ° C.

The effect of the present invention is finally confirmed by manufacturing a graphite electrode using calcined coke obtained by calcining raw coke and binder pitch, and examining its thermal expansion coefficient and puffing property. However, it can be judged more simply by examining the state of the calcined coke, especially the presence or absence of sintering. This is because the volatile component that volatilizes when the raw coke is calcined is coke before it comes out between the coke grains due to the presence of the fine grain coke, and it is sintered, but
It also supports the finding that is the basis of the present invention that the higher the VM, the larger the grain size of the fine-grain coke, which causes such a sintering phenomenon and becomes an obstacle.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the idea is not exceeded. In addition, according to JIS method, 1 g of raw coke sample from which water was previously removed was placed in a crucible with a lid and heated at 900 ° C. for 7 minutes, and the mass reduction rate at that time was calculated and displayed as wt% according to JIS method. .

Example-1 VM obtained by delayed coking is 4 to 5 wt.
%, 5 to 7 wt%, 7 to 10 wt% of raw coke, 3 points each, and 12 wt% of raw coke, each having a particle size of more than 0.8 mm,
A total of 70 raw coke samples with particle size adjusted to be over 1.7 mm, over 3.4 mm, over 6.7 mm, over 25 mm, over 50 mm, over 100 mm
It was calcined at 1450 ° C by a conventional method using a rotary kiln. As a result of judging the presence or absence of sintering of the obtained calcined needle coke, the following tendencies were observed.

Example 2 A raw coke having a volatile content of 6.0% was calcined at 1450 ° C. in a rotary kiln except for fine particles having a particle size of 1.7 mm or less. This calcined needle coke is crushed and sieved to appropriately mix the particle size,
To 100 parts of this was added 32 parts of binder pitch. After kneading, extrusion molding is performed to make a test piece of 25 mmφ × 120 mmL. After firing, the temperature range of 1000 ° C or higher is raised to 2800 ° C at a heating rate of 20 ° C / min, and held at 2800 ° C for 30 minutes to obtain graphite. It changed. The diameter was measured before and after graphitization to calculate the puffing.

Furthermore, the test piece after graphitization was ground to 20 mmφ × 100 mmL, and the thermal expansion coefficient between 25 and 125 ° C. was measured using this. As a result, the coefficient of thermal expansion was 4, 4 × 10 ⁻⁷ / ° C. and the puffing was 0.8%.

Comparative Example When the raw coke in Example-2 was used in the same manner as in Example-2 except that the fine grain portion was not removed, the coefficient of thermal expansion of the graphitized test piece obtained was 5.4 × 1.
0 ^-7 / ° C., Patsufuingu is 1.0%, Patsufuingu is slightly higher than Example, the thermal expansion coefficient is very high Katsuta.

(Effect) As described in detail above, according to the present invention, it is possible to stably produce a high-quality coke by an extremely simple operation,
In particular, when this needle coke is used, a graphite product such as an electrode having a very low coefficient of thermal expansion and little consumption can be manufactured. Moreover, generally, a material or treatment that lowers the coefficient of thermal expansion of the graphite product tends to increase the puffing, but despite the fact that the high-grade coke according to the present invention improves the thermal expansion characteristics of the graphite product, the puffing hardly occurs. It does not change, but rather shows a very remarkable phenomenon of becoming slightly lower, and provides a very effective method for substantially improving the properties of graphite.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Noritaka Takao No. 1 state town in Sakaide City No. 1 in Sakaide factory of Mitsubishi Kasei Co., Ltd. (56) References JP-A-55-3461 (JP, A) JP-B 61- 11991 (JP, B1)

Claims (2)

(57) [Claims] 1. When calcining a raw coke having a volatile content of about 4 to 10 wt% obtained by laying a carbonaceous raw material, it depends on the volatile content (VM) of the raw coke. A method for producing high-quality coke, which comprises calcining raw coke from which fine particles have been removed under the following selection conditions. B When VM <5wt%, at least fine particles with a grain size of 0.8mm or less b When 5wt% ≤ VM ≤ 7wt%, grain size is at least 1.7m
Fine particles less than m If VM> 7wt%, fine particles with a particle size of at least 3.4mm 2. When the selection condition is VM <5 wt%, at least fine particles having a grain size of 1.7 mm or less (5 wt% VM <7 wt%), the grain size is at least 3.4 m.
Fine particle portion of m or less When VM> 7 wt%, the fine particle portion has a particle diameter of at least 6.7 mm or less. Claim (1)
Method for producing high-quality coke described in paragraph