JPH07228872A - Method for selectively recovering desired pyrolytic component gas from coal - Google Patents

Abstract

PURPOSE:To selectively recover a desired component gas of pyrolytic gases generated from coal according to a relatively simple technique. CONSTITUTION:This method for selectively recovering a desired component gas comprises transferring coal into a pipe type pyrolizer (12), having plural pyrolytic zones (12a to 12e) at different temperatures and provided with a temperature gradient so as to advance the pyrolysis of the coal with the movement of the coal (11) in the interior thereof, carrying out the pyrolysis of the coal and selectively recovering the desired component gas from the pyrolytic zones (12c to 12e) corresponding to the temperature for producing the desired component gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively recovering a desired component gas of pyrolysis gas by utilizing the pyrolysis of coal.

[0002]

2. Description of the Related Art Coal produces various gases including high-calorie gas by thermal decomposition (carbonization). For example, in a coke oven, the main component of pyrolysis gas generated from coal with the progress of pyrolysis is coal tar, ethylene from gas liquid, higher hydrocarbons such as ethane, methane, carbon dioxide, carbon monoxide,
Change to hydrogen.

However, in the coke oven, all of the above component gases are collected in the same riser pipe, and the coke oven gas obtained is a mixture of these component gases. Therefore, when trying to obtain high-concentration hydrogen gas from this coke oven gas, which is used in the chemical industry, semiconductor industry, food industry, petroleum refining, etc. and is expected to be used as clean energy in the future, gas purification equipment for that purpose Is required separately.

Further, coke oven gas has the highest calorie of the by-product gas in the steel mill, but its lower calorific value is at most about 4,000 to 5,000 kcal / Nm ³ . Currently, in the steelworks, such coke oven gas is combined with blast furnace gas, converter gas and purchased fuel gas to meet various demands, but for future gas demands in the steelworks, It is said that it is difficult to deal with this alone, and higher calorie gas is desired.

By the way, against the background of effective utilization of coal resources, a technique of methanizing coke oven gas into higher calorie gas has been proposed (for example, Q. Yuan and BK). Huang, "Production of City Gas by Methanation under Normal Pressure" Proc. Pitts
burg Coal Conf. VOL. 6th, N
o. Vol. 12, pp 721-724, 1989).
However, when this methanation technology is carried out, a gas conversion facility such as a methanation reactor is required in addition to a coke oven, which causes a high cost. in addition,
According to this methanation technology, the carbon dioxide concentration in the obtained methanation gas becomes extremely high. Therefore, in order to put it into practical use, a separate decarbonation facility is required.

Further, in the time required from the charging of coal to the coke oven to the end of the carbonization, the high-calorie component gas having a high hydrocarbon content generated within the first 55 to 75% of the time, and the remaining gas A technique for separately recovering a component gas having a high hydrogen content generated within 45 to 25% of the time is disclosed in JP-A-57 / 57.
It is disclosed in Japanese Patent No. 3882. However, in the coke oven, the carbonization temperature differs between the furnace wall and the furnace center, and the components of the generated gas are not uniform in the furnace width direction. Therefore, mixing of hydrogen into the hydrocarbon component gas or mixing of hydrocarbon into the high-concentration hydrogen is unavoidable, and the target high calorie gas or hydrogen gas cannot be obtained in high concentration.

[0007]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to make use of the thermal decomposition of coal to obtain a desired component gas of the thermal decomposition gas generated from coal without the need for ancillary equipment, which is a relatively simple method. It is to provide a method of selectively recovering.

[0008]

Means and Actions for Solving the Problems The present inventors have
In the thermal decomposition process of coal, we paid attention to the fact that the components of gas generated differ depending on the thermal decomposition temperature. That is, in general, when coal is thermally decomposed, the coal exhibits thermal softening property at around 350 to 400 ° C., and coal tar and gas liquid are generated.
At around 450-500 ° C, the functional groups and side chains in the polymer that constitutes coal are decomposed to release higher hydrocarbons such as ethylene and ethane, methane, carbon monoxide, carbon dioxide, etc., while shrinking due to solidification. Indicates. When the temperature becomes higher, a large amount of hydrogen is released due to the decomposition of the periphery of the aromatic condensed ring, and at 700 ° C or higher, the main component of the pyrolysis gas becomes hydrogen, and finally residual carbon (char or coke) is generated. To do.

Therefore, if the component gas generated at each thermal decomposition temperature is extracted in the generation region, a desired component gas (for example, high calorie component gas, high concentration hydrogen gas) can be selectively obtained. As a result of further research on this point, the inventors of the present invention used a pipe-type device as a thermal decomposition device for coal and provided a temperature gradient to the thermal decomposition device so that thermal decomposition proceeded as the coal moved inside the device. It has been found that the above problem can be solved by recovering the desired component gas from the thermal decomposition zone corresponding to the generation temperature of the component gas.

That is, according to the present invention, there is provided a method for selectively recovering a desired component gas of the pyrolysis gas from coal, which has a plurality of pyrolysis zones at different temperatures, and the inside of the coal Is subjected to thermal decomposition by transferring the coal into a pipe-type thermal decomposition apparatus provided with a temperature gradient so that the thermal decomposition of coal proceeds as it moves, from the thermal decomposition region corresponding to the production temperature of the desired component gas. Provided is a method characterized by selectively recovering the desired component gas.

The present invention will be described in more detail below with reference to the drawings. FIG. 1 is a flowchart showing an example of the method of the present invention. As shown in FIG. 1, coal 11
The simple substance is supplied to the pipe-type thermal decomposition apparatus 12 of the present invention, which will be described in detail below, and the inside thereof is sequentially transferred by a pressure feeding means (not shown) for thermal decomposition. The coal used in the present invention is not particularly limited, and various coals such as peat, lignite, sub-bituminous coal, and bituminous coal can be used in a lump, granular or powder form.

The thermal decomposition apparatus 12 is provided with a temperature gradient (for example, from 100 ° C. to 1,000 ° C.) so that the thermal decomposition of coal proceeds from the coal supply side toward the outlet side. . Then, the pipe-type thermal decomposition apparatus 12 has a plurality of thermal decomposition zones at different temperatures along the temperature gradient (see FIG. 1).
Then, 5 areas 12a to 12e are set,
Each thermal decomposition zone is heated to its temperature by a heating means (not shown).

The thermal decomposition areas 12b to 12e are provided with recovery means 13 to 16 for recovering the thermal decomposition products generated in the respective areas to the outside of the apparatus. As described above, the thermal decomposition zones 12a to 12e are set to temperatures corresponding to the generation temperatures of the desired thermal decomposition products to be recovered, and the temperature gradient formed by the temperature of each thermal decomposition zone is A step gradient is preferable to a slope gradient. For example, the thermal decomposition zone 12a is set to a temperature of 100 ° C. to 300 ° C. to be a thermal decomposition preparation zone, and the next thermal decomposition zone 12b is set to 400 ° C.
The thermal decomposition zone 12c is set to a temperature of 450 ° C., and the high-calorie component gas mainly containing ethylene and ethane is recovered from the recovery means 13 and 14, and the thermal decomposition zone 12d is heated to 500 ° C.
The high-calorie component gas composed of a mixed gas of methane as a main component and carbon monoxide and carbon dioxide is recovered from the recovery means 15, and the thermal decomposition region 12e is set to a temperature of 700 ° C. or higher to hydrogen. The component gas containing as a main component can be recovered from the recovery means 16.

The moving speed of the coal in the apparatus 12 is set so that the coal can stay in each of the thermal decomposition zones 12b to 12e so that the generation of each of the thermal decomposition products is sufficiently completed in each of the thermal decomposition zones 12b to 12e. Speed is desirable.

The coal thus pyrolyzed is discharged from the device 12 as residual carbon. FIG. 2 shows a specific example of the pipe-type thermal decomposition apparatus 12 of the present invention described with reference to FIG.

The pyrolysis apparatus 12 shown in FIG. 2 has a double tube structure including a cylindrical inner tube 21 and a cylindrical outer tube 22 which is concentrically arranged apart from the inner tube 21. Inner tube 21 and outer tube 2
2 can be formed of, for example, SUS stainless steel. The inside of the inner pipe 21 defines a thermal decomposition region 23 of coal. The gap between the inner tube 21 and the outer tube 22 defines an annular heating area 24 for heating the pyrolysis area.

The heating region 24 is partitioned by donut-shaped disk-shaped heat insulating plates 25a to 25d, and the individual heating chambers 24a to 24 are separated.
It is divided into e. Each of the heating chambers 24a to 24e heats a corresponding portion (pyrolysis area) of the pyrolysis area 23 to a predetermined temperature. Corresponding to this heating, the pyrolysis area 23 has been described with reference to FIG. Pyrolysis area 12a ~
12e. That is, the heating chamber 24a is supplied with, for example, water vapor or low-level exhaust heat generated in the steel mill to set the temperature of the thermal decomposition region 12a to 100 to 300 ° C. In the heating chambers 24b to 24e, fuel gas and air are supplied from the respective supply sources 26 and 27 to the lines L1 and L.
2 is supplied as a mixture from each confluence line L3, and is burned in each burner B inside each heating chamber 24b to 24e to heat the thermal decomposition zones 12b to 12e to, for example, the temperatures illustrated with reference to FIG. The flow rate of the fuel gas is such that the fuel gas and the air are heated in the heating chambers 24b to 24b at a ratio according to the target temperature.
It is adjusted by each flow rate adjusting valve V in the preceding stage of the merging line L3 so as to be burned in 24e. The number of burners B in each heating chamber 24b to 24e can be appropriately determined according to the volume of the heating chamber.

Inside the inner pipe 21, a screw feeder type extruder 28 is installed as a means for feeding the coal 11. By the rotational driving of the extruder 28, the thermal decomposition area 23
The coal 11 supplied from the hopper 29 is transferred to the thermal decomposition region 23 with a sufficient residence time in each of the thermal decomposition regions 12b to 12e. For example, the coal 11 is transferred from the supply unit to the outlet at a low speed for several hours to about 24 hours depending on the volume of the pyrolysis region 23. Heating chambers 24a-24e
Has an annular shape and is transferred while undergoing thermal decomposition while being driven by the extruder 28 to rotate in the thermal decomposition area 23.
The degree of thermal decomposition in each of the thermal decomposition regions 12b to 12e becomes uniform.

The thermal decomposition products of coal in the thermal decomposition zones 12b to 12e are collected by the recovery means 13 to 1 described with reference to FIG.
6 corresponding to the recovery pipes 13a to 13e, 14a to 14c,
Recovered from 15a-15d and 16a-16b.
The recovery pipes 13a to 13e, 14a to 14c, 15a
.About.15d and 16a to 16b are respectively connected to a common recovery pipe (not shown), and each thermal decomposition product is collected.

The coal thus pyrolyzed is recovered in the container 31 as residual carbon 30 from the device 12. In addition,
The thermal decomposition zones are not limited to the five shown in the above example, but can be set appropriately according to the desired generation temperature of the component gas, the type of coal, and the like.

[0021]

EXAMPLES Examples of the present invention will be described below. Example 1
The thermal decomposition apparatus 12 shown in FIG.
The temperature at 12e and the residence time of the coal were set as follows.

Pyrolysis zone Temperature (° C.) Residence time (hours) 12a 400 3 12b 450 2 12c 500 1 12d 700 1 12e 800 1 Prima charcoal (made in Indonesia) as coal 11 from hopper (ash content 4.6%, volatile matter) 43.7%) about 30 kg
It was supplied at a rate of / hour. The screw feeder type extruder 28 was rotated at a low speed, and the time required from the supply of coal 11 to the discharge was about 9 hours.

While the coal 11 was transferred in the pyrolysis zones 12a-12e set to the above-mentioned temperature, the pyrolysis gas produced from the recovery pipes 13-16 provided in each pyrolysis zone was recovered. . The composition of the obtained gas, the lower heating value and the gas generation amount are summarized in Table 1. Further, while the coal 11 was transferred in the pyrolysis zones 12a to 12c for about 6 hours, tar and gas liquid were recovered together with the pyrolysis gas at 4.8 kg / hour.

Example 2 In the thermal decomposition apparatus 12 shown in FIG. 2, only the thermal decomposition zones 12a and 12b were used, and the respective temperatures and residence times were set as follows.

Pyrolysis zone Temperature (° C) Residence time (hour) 12a 300 2 12b 400 5 About 30 kg of prima charcoal (produced in Indonesia) (ash content 4.6%, volatile content 43.7%) from the hopper as coal 11
It was supplied at a rate of / hour. The screw feeder type extruder 28 was rotated at a low speed, and the time required from the supply of coal 11 to the discharge was about 8 hours.

While the coal 11 was transferred in the pyrolysis zones 12a and 12b set to the above-mentioned temperature, the pyrolysis gas produced from the recovery pipes 13 and 14 provided in the respective pyrolysis zones was recovered. . The composition of the obtained gas, the lower heating value and the gas generation amount are summarized in Table 1. Further, while the coal 11 is transferred in the pyrolysis zones 12a and 12b for about 7 hours, the tar and the gas liquid are 4.1 kg together with the pyrolysis gas.
/ Hour recovered.

Example 3 In the thermal decomposition apparatus 12 shown in FIG. 2, thermal decomposition zones 12a-1
Only 2d was used and the temperature and coal residence time in each pyrolysis zone were set as follows.

Pyrolysis zone Temperature (° C.) Residence time (hours) 12a 300 2 12b 400 3 12c 500 2.5 12d 800 2 Prima coal (produced from Indonesia) as coal 11 from hopper (ash content 4.6%, volatile content 43 0.7%) about 30 kg
It was supplied at a rate of / hour. The screw feeder type extruder 28 was rotated at a low speed, and the time required from the supply of coal 11 to the discharge was about 10.5 hours.

While the coal 11 was transferred in the pyrolysis zones 12a to 12d set to the above-mentioned temperature, the pyrolysis gas produced from the recovery pipes 13 to 15 provided in each pyrolysis zone was recovered. . The composition of the obtained gas, the lower heating value and the gas generation amount are summarized in Table 1. Further, while the coal 11 is transferred in the pyrolysis zones 12a to 12c for about 7.5 hours, the tar and the gas liquid are 5.1 kg together with the pyrolysis gas.
/ Hour recovered.

Example 4 In the thermal decomposition apparatus 12 shown in FIG. 2, only the thermal decomposition zones 12a and 12b were used, and the respective temperatures and residence times were set as follows.

Pyrolysis zone Temperature (° C.) Residence time (hours) 12a 300 1 12b 500 1.5 Prima charcoal (produced in Indonesia) (ash content 4.6%, volatile content 43.7%) from the hopper as coal 11 30 kg
It was supplied at a rate of / hour. The screw feeder type extruder 28 was rotated at a low speed, and the time required from the supply of coal 11 to the discharge was about 2.5 hours.

While the coal 11 was transferred in the pyrolysis zones 12a and 12b set to the above-mentioned temperature, the pyrolysis gas produced from the recovery pipes 13 and 14 provided in each pyrolysis zone was recovered. . The composition of the obtained gas, the lower heating value and the gas generation amount are summarized in Table 1. Further, while the coal 11 is transferred in the pyrolysis zones 12a and 12b for about 2 hours, tar and gas liquid are 3.9 kg together with the pyrolysis gas.
/ Hour recovered.

Example 5 In the thermal decomposition apparatus 12 shown in FIG. 2, only the thermal decomposition zones 12a and 12b were used, and the respective temperatures and residence times were set as follows.

Pyrolysis zone Temperature (° C) Residence time (hours) 12a 400 1 12b 500 1.5 Optimum coal (produced in South Africa) as coal 11 from hopper (ash content 10.5%, volatile content 32.9%) Was supplied at a rate of about 30 kg / hour. The screw feeder type extruder 28 was rotated at a low speed, and the time required from the supply of coal 11 to the discharge was about 2.5 hours.

While the coal 11 was transferred in the pyrolysis zones 12a and 12b set at the above-mentioned temperature, the pyrolysis gas produced from the recovery pipes 13 and 14 provided in each pyrolysis zone was recovered. . The composition of the obtained gas, the lower heating value and the gas generation amount are summarized in Table 1. Further, while the coal 11 is transferred in the pyrolysis zones 12a and 12b for about 2 hours, tar and gas liquid are 3.9 kg together with the pyrolysis gas.
/ Hour recovered.

[0036]

[Table 1]

Comparative Examples 1 and 2 The coke oven gas and the methanated coke oven gas obtained by the "production of city gas by methanation under normal pressure" are compared with the high calorie component gas obtained in Examples 1 to 5 above. It is also shown in Table 1.

As can be seen from the above results, according to the present invention, the desired pyrolysis component gas can be selectively recovered. The high-calorie gas obtained by the present invention has a high lower heating value (for example, the lower heating value of the component gas recovered from the 400 ° C. thermal decomposition zone 12a in Example 1 is 10,200 kcal / Nm ³ ). On the other hand, the carbon dioxide concentration and hydrogen concentration in the high-calorie gas were low. Further, the hydrogen content of the obtained high-concentration hydrogen gas was also high (for example, the thermal decomposition zone 1 of 800 in Example 1).
The hydrogen content of the component gas recovered from 2e is 89 vol.
Reach%).

[0039]

As described above, according to the present invention, a desired component gas of the pyrolysis gas generated from coal, such as a high calorie gas or hydrogen gas, is used as a relatively simple device without requiring any auxiliary equipment. It can be selectively collected by the method.

[Brief description of drawings]

FIG. 1 is a flowchart showing the method of the present invention.

FIG. 2 is a partial cross-sectional view showing a specific example of a thermal decomposition apparatus for carrying out the method of the present invention.

[Explanation of symbols]

11 ... Coal, 12 ... Pyrolysis device, 12a-12e ... Pyrolysis region, 13-16 ... Recovery means, 13a-16b ... Recovery pipe, 21 ... Inner pipe, 22 ... Outer pipe, 23 ... Pyrolysis region, 24
a to 24e ... Heating chamber, 28 ... Screw feeder type extruder.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C10J 3/02 Z // C10B 27/02 C10G 1/02 2115-4H (72) Inventor Takeshi Konishi Marunouchi 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Tsutomu Shikata Nihon Koube Co., Ltd. 1-21-2 Marunouchi, Chiyoda-ku, Tokyo Shinji Ishii Tokyo 1-2 1-2 Marunouchi, Chiyoda-ku Nihon Steel Pipe Co., Ltd.

Claims (1)

[Claims] 1. A method for selectively recovering a desired component gas of its pyrolysis gas from coal, comprising a plurality of pyrolysis zones of different temperatures, wherein the coal is treated as the coal moves inside. Coal is transferred into a pipe-type thermal decomposition apparatus provided with a temperature gradient so that thermal decomposition progresses and subjected to thermal decomposition, and the desired component gas is removed from the thermal decomposition zone corresponding to the generation temperature of the desired component gas. A method characterized by selectively collecting.