JPH0823018B2 - Liquefaction coal pretreatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for pretreatment of raw coal for direct liquefaction.

2. Description of the Related Art Liquefaction of coal is intended to produce a liquid fuel or a synthetic chemical raw material from solid coal which is a polymer carbonaceous compound, and many liquefaction methods have been proposed so far. These liquefaction methods are roughly classified into two, a direct liquefaction method and an indirect liquefaction method, according to their principles.

Of these, the direct liquefaction method generally stabilizes the thermal decomposition fragments of coal with gaseous hydrogen or a hydrogenated solvent under high temperature and high pressure.

In this case, since solid coal is quantitatively fed into the high-pressure reaction system, usually coal is first pulverized and slurried with a solvent. This coal slurry is fed into a high-temperature and high-pressure reactor through a preheater, reacted with hydrogen and liquefied. The reactor effluent is decompressed to remove gas components, then further liquefied insolubles and mineral components are removed as necessary, and finally fractionated into light oil, heavy oil, etc. in a distillation step.

In particular, problems in industrialization of such a liquefaction process include abrasion in the liquefaction process system due to the presence of mineral components contained in coal, clogging due to solid content deposition, and corrosion.

Coal generally contains about 5 to 40% of mineral components, although it depends on the endowment state and mining conditions.

Wear occurs remarkably before and after the reactor of the high pressure system, so that particular attention has been paid to the selection of materials for the high pressure slurry feed pump and the valve used for depressurization after the reaction. For solid deposits in the reactor (mainly thought to be due to the formation of carbon salts of Ca), the solid components are regularly extracted from the lower part of the reactor at some test plants in Japan. There is an example of dealing with it.

Regarding corrosion, there is a report of stress corrosion cracking due to chlorine in the distillation column at the US SRC test plant.

The problems caused by the presence of these mineral components differ depending on the type of coal used, but basically they will be considerably improved by reducing the mineral components before the liquefaction reaction.

On the other hand, in general, such a liquefaction reaction consumes 2 to 8% by weight of hydrogen based on the amount of coal supplied, and this hydrogen accounts for a major portion of the cost of the liquefaction product.

Therefore, the improvement of the oil yield / hydrogen consumption ratio becomes a big problem.

Histologically, vitrinite with high liquefaction reactivity
The content of the inertinit group, which is inferior in reactivity to the exgenit group, is extremely wide, ranging from a few% of the case of Japanese coal to 50% or more of the case of Australian coal.

Therefore, in order to improve the oil yield / hydrogen consumption ratio in the liquefaction process, it is considered effective to reduce the inertin group having low liquefaction reactivity.

Conventionally, coal with a high content of mineral components has been subjected to coal preparation treatment, but this coal preparation treatment is mainly performed for the purpose of removing the mineral components, and the clean coal that is prepared also generally contains 5 to 15% of mineral components. I'm out. Also, the inertinite group, which has low liquefaction reactivity, was not targeted for removal in the pretreatment of coke or combustion coal from the viewpoint of heat generation recovery.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The inventors of the present invention consider that the vitrinite and exgenit groups in which coal has high liquefaction reactivity and the inertinit group inferior in reactivity to them Focusing on the fact that it is composed, it is necessary to remove both the inertinite group and mineral components in order to improve the economic efficiency and operability of the liquefaction process. Specific gravity separation method, flotation method, pressure flotation method , Dewatering and deashing tests of liquefaction coal by various pretreatment methods such as underwater granulation method, and further liquefaction test of the obtained clean coal to improve the oil yield / hydrogen consumption ratio. We measured it and found that it has advantages and disadvantages.

For example, the specific gravity separation method can be used to reduce the contents of both the inertinite group and the mineral component, but when the removal rate is increased, the clean coal recovery rate is rapidly decreased.

Using Australian sub-bituminous coal as the raw material coal, the specific gravity separated products clean coal A and clean coal B using the heavy liquid agent whose specific gravity was adjusted to 1.39 and 1.33 by mixing water and fine magnetite of 325 mesh or less were used as the raw materials. Using 3 autoclaves, coal sample 200g, tetralin 600g, red mud 10g and sulfur 1g as catalyst, hydrogen initial pressure 70Kg / cm ² , temperature rising rate 5 ℃ / min, reaction temperature 450 ℃, reaction time 60 minutes The results of the liquefaction test after hydrogenation are shown in Table 1.

As the ash removal rate increases, the inertinite content also decreases, and the oil yield / hydrogen consumption ratio when the clean coal is liquefied improves, but when the ash removal rate increases, the clean coal recovery rate decreases rapidly. There are difficulties.

A similar tendency was observed in the flotation method and the pressure flotation method.

Next, Table 2 shows the results of similar tests performed using the underwater granulation method.

For clean coal C and clean coal D in Table 2, coal liquefaction solvent was used as an additive oil for granulation, and 40% by weight of this was added to the dry raw coal, and the concentration of the dry raw coal in water was 20% by weight. It was obtained at a granulation stirring speed of 1600 times per minute and a granulation time of 15 minutes and 120 minutes.

When the underwater granulation method is used, the ash removal rate is increased and the clean coal recovery rate is gradually lowered, but when the clean coal is liquefied, the oil yield / hydrogen consumption ratio is improved at all. I can't.

As described above, the known pretreatment method has merits and demerits, and is not satisfactory as a pretreatment method for liquefaction raw material coal having a high effect of improving the economical efficiency and operability of the liquefaction plant.

Structure of the Invention Means for Solving Problems The pretreatment method for liquefying coal according to the present invention comprises sequentially treating raw material coal by a gravity separation method and then by an underwater granulation method.

One embodiment of the present invention will be described in detail below with reference to FIG.

Coking coal is supplied from line 20 to crusher 1 and after crushing 5
The viscous sieve 2 of 10 mm is used for sieving, the coal on the sieve is circulated to the crusher 1 by the line 21, the coal under sieve is supplied to the vibrating sieve 3 of 0.3 to 0.7 mm, and the pulverized coal under sieve is lined. The coal discharged on the sieve 23 is supplied to the heavy liquid cyclone (specific gravity separator) 4 from the line 24, and the heavy liquid agent sent from the heavy liquid reservoir 7 to the line 25 causes the floating coal of low specific gravity and the high specific gravity It is separated into slippery.

Coal contains inactive inertinite components and ash in addition to active components such as vitrinite and ecdinite, but active components such as vitrinite and ecdinite are concentrated on the levitation coal side with low specific gravity, and the inert inert component And ash have high specific gravity Concentrated to the side.

The levitation coal / heavy liquid mixture having a low specific gravity is sent to the drainage washing sieve 5 through a line 26, where it is washed with water supplied from a line 28, and the separated heavy liquid agent is sent to a heavy liquid reservoir 7 through a line 30.

High specific gravity Is sent to the drainage washing screen 6 through a line 27, washed with water supplied from a line 28, and the drained heavy liquid agent is sent to a heavy liquid reservoir 7 through a line 33.

The heavy liquid diluted with the washing water on the drainage washing sieves 5 and 6 is passed through the magnetizer 8 via the line 31 to the concentrator 9 respectively.
Send to The heavy liquid concentrated in the concentrator 9 is sent to the magnetic ore separator 10 and separated into a heavy liquid agent and pulverized coal / mineral substances. The separated heavy liquid agent is sent to the densifier 11 to remove excess water, and then sent to the heavy liquid reservoir 7 through the demagnetizer 12.

As the heavy liquid agent, an iron-based slurry such as magnetite, pyrite slag, red mud, and iron sulfate is preferable, and its specific gravity is 1.5 or less.
It is preferable to use those of 1.4 or less.

In this way, since levitation coal in which the vitrinite and ecdinite components are concentrated can be obtained from the line 29, it is finely pulverized by the fine pulverizer 13 together with the undersize carbon from the line 23,
It is sent to the granulator 14 and granulated using an appropriate binder. FIG. 1 shows the case where the heavy oil obtained in the liquefaction process of coal supplied from the line 34 is used as a binder.

The granulated product is sent to the liquefaction process after separating the water content and the mineral substances attached by the dewatering sieve 15.

While from line 32 The laboratory sends it to the gasification reactor 16, burns it with an oxygen-rich gas, converts CO into hydrogen in the aqueous glass reactor 17, and sends it to the liquefaction process for use in the hydrogenation reaction.

Example 1 Australian sub-bituminous coal was crushed to a diameter of 0.5 to 5 mm, treated with a heavy liquid agent to separate the specific gravity, and then combined with about 0.5% sieved coal which cannot be treated by the specific gravity separation of about 10% generated by the pulverization. It was finely pulverized, and further, the heavy oil from the liquefaction process was granulated in water using the binder as a binder to separate the attached water and mineral substances. Using clean coals E and F obtained by changing the operating conditions as a raw material, using 3 autoclaves, coal sample 200g, tetralin 600g, red mud 10g and sulfur 1g as catalyst, hydrogen initial pressure 70Kg / cm ² , temperature rising rate Table 3 shows the results of a liquefaction test conducted by adding hydrogen under the conditions of 5 ° C./min, reaction temperature of 450 ° C., and reaction time of 60 minutes.

Note that the clean coal E and the clean coal F were subjected to specific gravity separation using a specific gravity agent having a specific gravity of 1.50 and 1.40, respectively, and the clean coal E was the same as the clean coal D and the clean coal F in Table 2 below. It is a product produced by underwater granulation under the conditions (addition amount of coal liquefied solvent 40% by weight, coal concentration 20% by weight, stirring speed 1600 times per minute, granulation time 15 minutes and 120 minutes).

In the gravity separation method, as shown in Table 1, the content of inertinite decreases as the ash removal rate increases, and the oil yield / hydrogen consumption ratio improves when the clean coal is liquefied, but the ash removal If the rate is increased, the clean coal recovery rate will decrease rapidly. Also, it is difficult to handle with a practical device −0.
About 10% of pulverized coal of 5 mm is also generated, and if the loss of this amount is also added, the recovery ratio of refined coal by the gravity separation method will be further reduced.

In the case of the underwater granulation method, there is no loss of pulverized coal as in the specific gravity separation method, and as shown in Table 2, the reduction of the clean coal recovery rate by increasing the ash removal rate is gradual. No improvement in the oil yield / hydrogen consumption ratio is observed when the charcoal is liquefied.

On the other hand, the method of the present invention in which the specific gravity separation method and the underwater granulation method are sequentially performed so that the ash levels are almost the same as those in the cases of the specific gravity separation method of Table 1 and the underwater granulation method of Table 2 respectively. As shown in Table 3, the reduction of the clean coal recovery rate by increasing the ash removal rate is small, and the oil yield / hydrogen consumption ratio is improved.

FIG. 2 shows the recovery rate of clean coal (shown on the horizontal axis) when various pretreatment methods for coal for liquefaction were used, and the oil yield / hydrogen consumption ratio when the clean coal was liquefied by hydrogenation ( (Shown on the vertical axis), where A and B are the data when only the specific gravity separation method is used as the pretreatment (see Table 1), and C and D are only the underwater granulation method as the pretreatment. Data when used (see Table 2), E and F are data when sequentially treated by the gravity separation method according to the present invention and then by the underwater granulation method (see Table 3).
Indicates. The symbol G is data when raw coal was directly liquefied.

From this figure, by performing a pretreatment combining the gravity separation method with an underwater granulation method that does not have the effect of improving the oil yield / hydrogen consumption ratio, when using coal with almost the same level of ash content, only the gravity separation method is used. It can be seen that the oil yield / hydrogen consumption ratio during liquefaction of clean coal can be improved with less loss of raw coal (that is, higher recovery rate of clean coal).

EFFECTS OF THE INVENTION When the coal pretreated according to the present invention is used as a raw material, the oil yield per unit hydrogen consumption is improved, and the content of mineral components is decreased. Blockage and corrosion due to deposits of

By carrying out the underwater granulation method in the subsequent step, the water content of the clean coal decreases. In other words, in the case of refined charcoal with specific gravity separation, the product is simply drained on a sieve, so its surface is covered with water and the water content is high. Since the surface is covered with oil and repels moisture, the moisture content is lower than that of coal after specific gravity separation, even if only draining with a sieve. Therefore, the underwater granulated coal is advantageous for liquefaction.

Since the oil yield is improved, the liquefaction device can be made compact.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a process flow for carrying out the method of the present invention, and FIG. 2 is a clean coal recovery rate in the case of using various liquefaction coal pretreatment methods and hydrogenation of the clean coal. It is a figure which shows the relationship of the oil yield / hydrogen consumption ratio at the time of liquefying.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Hideki, 3-290, Matsugaoka, Nagareyama-shi, Chiba (56) Reference JP-A-60-212484 (JP, A)

Claims (1)

[Claims] 1. A raw material coal crushed to a size of 10 mm or less has a specific gravity of 1.5.
A pretreatment method for liquefying coal, which comprises treating by a specific gravity separation method using the following heavy liquid agent, finely pulverizing the obtained levitation coal having a low specific gravity, and then successively treating it by an underwater granulation method.