JPH059477A - Method of rapid thermal decomposition of coal - Google Patents

Abstract

PURPOSE:To thermally decompose coal economically by a simple and convenient operation at a high conversion into a hydrocarbon gas and tar. CONSTITUTION:A coal powder is thermally decomposed rapidly by keeping the powder in contact with the vapor of a hydrogen-donating solvent at 70-200 deg.C for 5-20min, heating the powder to 500-900 deg.C at a rate of temp. rise of 500 deg.C/sec or higher in an inert or hydrogen gas atmosphere, and keeping the powder at 500-900 deg.C in the atmosphere.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for rapidly pyrolyzing coal to efficiently produce useful gases and tars. In the present specification, "%" and "part"
The terms "wt%" and "parts by weight" respectively mean.

[0002]

2. Description of the Related Art Hydrocarbon gas obtained by decomposing coal, which is a solid fuel, and liquid products such as benzene, toluene, and xylene are more useful than coal. Conventionally, as a method for producing hydrocarbon gas and tar using coal as a raw material, a method of rapidly heating finely pulverized coal to 700 to 1000 ° C. and rapidly pyrolyzing the coal with a reaction time of several seconds to several tens of seconds Are known ("Fuel Association Magazine" Vol. 67, No. 1 (1988), pp. 14-27). However,
In this method, the subsequent pyrolysis is suppressed by the crosslinking of the pyrolysis fragments generated during the pyrolysis of coal at 400 to 500 ° C in the temperature rising process, and the conversion rate to hydrocarbon gas and tar is low.

As a method for increasing the conversion rate of coal to hydrocarbon gas and tar, there is a method of stabilizing the reaction by giving hydrogen to the pyrolysis fragments at a timely timing to prevent cross-linking (JP-A-2-151690). .. In this method, a liquid hydrogen-donating solvent is infiltrated into coal powder under high pressure to swell the coal and then rapidly decompose it to improve the conversion rate. However, this method uses a large amount of expensive liquid hydrogen-donating solvent, the operation is complicated, and the economical efficiency is poor.

[0004]

SUMMARY OF THE INVENTION The main object of the present invention is to provide a method for pyrolyzing coal which is simple in operation and excellent in economical efficiency and has a high conversion rate to hydrocarbon gas and tar. ..

[0005]

The present inventor has conducted various studies in view of the current state of the art as described above, and as a result, after contacting coal with a vapor of a hydrogen donating solvent under a specific temperature condition, In the case of rapid heating to the zone, molecules of the hydrogen-donating solvent penetrate into the micropores inside the coal, and during rapid heating, the hydrogen-donating solvent molecules that permeate into the inside of the coal transfer hydrogen to the pyrolysis fragment. It has been found that conversion of coal to hydrocarbon gas and tar can be increased because of the efficient feeding.

[0006] That is, the present invention provides the following method: "In a rapid thermal decomposition process of coal, the coal powder is contacted with vapor of a hydrogen donating solvent at 70 to 200 ° C for 5 to 20 minutes. After that, the coal powder is heated to 50 ° C./sec or more in an inert gas or hydrogen gas atmosphere at a heating rate of 50 ° C./sec.
A rapid thermal decomposition method for coal, which comprises heating to 0 to 900 ° C and holding it. "

The types of coal which are the subject of the method of the present invention include:
There are no restrictions on the place of origin. In order to increase reactivity, coal is preferably used in the form of powder having a particle size of about 100 mesh or less.

In the method of the present invention, first, as the first step, the coal is brought into contact with the vapor of the hydrogen donating solvent at 70 to 200 ° C. for about 5 to 20 minutes to allow the molecules of the hydrogen donating solvent to move inside the coal. Permeates the micropores and swells the coal. The vapor pressure of the hydrogen donating solvent is not particularly limited, but is usually normal pressure to about 0.5 MPa. The hydrogen donating solvent, tetralin, tetrahydroquinoline, dihydroanthracene, tetrahydroanthracene, dihydrophenanthrene, tetrahydrophenanthrene, dihydropyrene, tetrahydropyrene, dihydrochrysene,
Tetrahydrochrysene and the like are exemplified. If the temperature in the first stage is lower than 70 ° C, the swelling of coal is not sufficiently performed, and the desired effect cannot be obtained. On the other hand, 20
When the temperature is higher than 0 ° C, the coal swells well, but an excessive amount of solvent is added, which is economically disadvantageous. If the contact time is less than 5 minutes, the swelling of coal will be insufficient and the desired effect cannot be obtained. on the other hand,
If it exceeds 20 minutes, the swelling of coal is performed well, but an excessive amount of solvent is added, which is economically disadvantageous. The permeation amount of the hydrogen donating solvent into coal varies depending on the type of coal, the type of hydrogen donating solvent, etc., but is usually about 1 to 10% of the weight of coal. 50 to 50 in coal components
About 80% is in a non-covalent bond state, and these binding sites are decomposed at 400 to 500 ° C. and cross-linked to suppress further decomposition. The non-covalent bond is composed of van der Waals bonds, hydrogen bonds, etc., and has a low binding energy. Therefore, in the first step of the method of the present invention, hydrogen-donating solvent molecules are permeated at a low temperature of about 70 to 200 ° C. Even in these cases, it is speculated that these weak bonds loosen and that subsequent rapid heating readily decomposes the coal under the supply of hydrogen.

In the method of the present invention, then, as a second step, the coal which has been subjected to the first step treatment is directly cooled in an atmosphere of an inert gas such as nitrogen gas or helium gas and / or hydrogen gas without cooling. Temperature increase up to a temperature range of about 900 ° C. (more preferably up to a temperature range of 700 to 800 ° C.) at a temperature increase rate of 500 ° C./second or more (more preferably at a temperature increase rate of 1000 ° C./second or more) At the same temperature for about 1 to 60 seconds (more preferably 5 to 1
Hold for about 5 seconds, perform thermal decomposition, and then rapidly cool. The pressure of the inert gas and / or hydrogen gas is not particularly limited, but is usually normal pressure to 10.0 MPa. If the rate of temperature rise is too low, an insufficient effect due to the gradual temperature rise will be obtained, and the yield of tar + organic gas + inorganic gas will be low. The thermal decomposition temperature and time must be selected so that secondary reaction such as decomposition of the reaction product or polymerization reaction does not occur. The thermal decomposition may be carried out under a pressure of from normal pressure to about 10 MPa. The reason for quenching after the thermal decomposition reaction is also to suppress the secondary reaction of the products (hydrocarbon gas and tars).

[0010]

According to the method of the present invention, the following remarkable effects are achieved. (1) Since it is not necessary to use a large amount of expensive hydrogen donating solvent, it is excellent in economic efficiency. (2) Complicated operations when using the hydrogen donating solvent in a liquid form can be omitted. (3) The conversion rate from coal to hydrocarbon gas and tar is high.

[0011]

EXAMPLES Examples will be shown below to further clarify the features of the present invention.

Example 1 and Comparative Example 1 As a first step, Pacific charcoal powder crushed to 200 mesh or less was treated with tetralin vapor at a temperature of 100 ° C. under normal pressure.
It was contacted for 0 minutes and swollen. The amount of tetralin permeated into the coal was 8%. Then, the coal powder sample that has completed the first step is subjected to high-frequency heating in a nitrogen stream to 50
650 ° C, 750 ° C and 850 at a heating rate of 0 ° C / sec.
Rapidly heat each to ℃, hold at the same temperature for 2 seconds,
The second stage of the invention was carried out. Then, the product was rapidly cooled by He gas at room temperature introduced into the reaction tube, and tar was collected on the reaction tube wall and the quartz wool filled in the reaction tube. Figure 1 shows the results of heat treatment (tar yield and conversion).
Shown in. In addition, as a comparative example, the results obtained when only the second step is performed without the above first step are also shown in FIG. In FIG. 1, each curve shows the following results. l ... Tar yield according to Example 1 ll ... Conversion rate according to Example 1 (tar + hydrocarbon gas +
Inorganic gas yield) lll ... Tar yield according to Comparative Example 1 lV ... Conversion rate according to Comparative Example 1 (tar + hydrocarbon gas +
Inorganic Gas Yield) As is clear from the results shown in FIG. 1, after the coal is treated with the vapor of the hydrogen donating solvent, rapid pyrolysis is performed at 700 to 900 ° C., whereby the tar yield and the conversion rate are increased. Significantly improved.

Example 2 and Comparative Example 2 As the first step, Moell coal powder pulverized to pass through 200 mesh or less was contacted with tetralin vapor at a temperature of 100 ° C. under normal pressure to swell. Then, the coal powder sample that has completed the first step is subjected to high-frequency heating in a nitrogen stream to 500
The second step of the present invention was carried out by rapidly heating to 750 ° C. at a temperature rising rate of ° C./sec and maintaining the same temperature for 2 seconds. FIG. 2 shows the relationship between the amount of tetralin impregnated and the amount of volatile matter increase per 1 g of tetralin. Also, as a comparative example, 2 in the first stage
Moell charcoal powder 100 crushed to less than 00 mesh
And 50 parts of tetralin were heated in an autoclave under a high-pressure N ₂ gas atmosphere of 1 MPa at 250 ° C. for a predetermined time to swell, and then the second step was carried out in the same manner as in Example 2 above. The results are also shown in FIG. According to the method of the present invention, the amount of volatile matter produced per unit weight of tetralin is high although the amount of impregnated tetralin is as small as about 3 to 8%. On the other hand, in the case of the comparative example method in which tetralin is impregnated into coal under high pressure, the amount of volatile matter produced per unit weight of tetralin is low, although the amount of tetralin impregnated is extremely large. According to the method of the present invention, such a difference is caused because tetralin is permeated as a molecule even inside the coal, whereas in the comparative example method tetralin is not sufficiently permeated inside the coal. Conceivable.

[Brief description of drawings]

FIG. 1 is a graph showing the effect on the tar yield and conversion rate by the first-stage treatment of the method of the present invention.

FIG. 2 is a graph showing the effect of increasing volatile components per unit weight of tetralin by the first-stage treatment of the method of the present invention.

Claims (1)

Claim: What is claimed is: 1. In a rapid thermal decomposition method for coal, after the coal powder is contacted with steam of a hydrogen donating solvent at 70 to 200 ° C for 5 to 20 minutes, the coal powder is inactivated. 500 at a heating rate of 500 ° C / sec or more in a gas or hydrogen atmosphere
A method for rapid thermal decomposition of coal, characterized by heating to ~ 900 ° C and holding.