AU2012288216B2 - Production method of coal gas and methane - Google Patents

Abstract

A method for producing coal gas that includes hydrogen gas and carbon monoxide gas, using a coal gasification reactor (4) provided with a lower reaction vessel (11) and an upper reaction vessel (13), wherein the method is provided with: a step for supplying first coal, hydrogen, and water vapor to the lower reaction vessel (11), in order to cause high-temperature gas to be generated by a partial oxidation reaction; a step for supplying second coal while also introducing the high-temperature gas to the upper reaction vessel (13), in order to pyrolize the second coal; and a step for adjusting an increase or reduction in the amount of the second coal supplied to the upper reaction vessel (13), in order to control to 1,000°C or higher the temperature of coal gas flowing out from an outlet of the upper reaction vessel (13).

Description

I PRODUCTION METHOD OF COAL GAS AND METHANE Technical Field [0001] 5 The present invention relates to a method for producing combustible gases by gasifying coal using an oxidizer such as oxygen and steam, and in particular, relates to a production method of coal gas including hydrogen gas and carbon monoxide gas and a production method of methane. Priority is claimed on Japanese Patent Application No. 2011-162102, filed July 10 25, 2011, the contents of which are incorporated herein by reference. Background Art [0002] Conventionally, in order to produce effectively combustion gases and the like by 15 gasifying coal, various configurations of a gasification reactor such as one having a fixed bed, a moving bed or a fluidized bed (entrained bed) are studied. The fluidized bed type of the gasification reactor which is the one of these types has become the major one of the gasification reactor in recent years by the reason of which high capacity is easy to achieve and load following capability is high, or the like, when the gasification reactor is 20 considered for the use of a power generation specifically. [0003] In the gasification reactor having the fluidized bed, a high temperature gas of 1300 to 1800'C having hydrogen and carbon monoxide as a major component is produced by the partial oxidation reaction of coal using an oxidizer such as oxygen, air, 25 or the like, and the sensible heat of this high temperature gas is recovered using steam or 2 the like generally. As the gasification reactor producing more gas, tar, BTX (benzene, toluene and xylene), and char by using the sensible heat of this high temperature gas to a thermal cracking reaction of coal, there is a proposal of a thermal cracking gasification reactor of coal having two-step and double structure such that a partial oxidation reaction of coal is performed at the lower chamber of the gasification reactor and a thermal cracking reaction is performed at the upper chamber of the gasification reactor (refer to Patent Document 1). [0004] In the gasification reactor described in the Patent Document 1, in the upper chamber of the gasification reactor, hydrogen gas and coal are mixed with a high temperature partial oxidation gas of coal produced at the lower chamber of the gasification reactor, and a thermal cracking reaction of coal is taken place. By this thermal cracking reaction of coal, a thermal cracking gas including hydrogen, carbon monoxide, methane, and the like; tar, BTX, and char are produced. In addition, by the reaction between tar and hydrogen gas, tar is reformed and BTX is further produced. Patent Documents [0005] [Patent Document 1] Japanese Patent No. 4088363 [0006] In the gasification reactor described in Patent Document 1, there is a problem as described later, because a large amount of tar is produced by the thermal cracking reaction of coal. In the method described in Patent Document 1, in order to lighten the produced tar, a facility to recycle part of product gas as hydrogen gas is required. In addition, part of the 3 product gas is recycled, and thus, the amount of the final product is reduced. In addition, when the product gas is prepared, tar is separated from the thermal cracking gas by a cooler, and thus, a facility to recover the tar is required. Furthermore, cooling is performed when the tar is separated from the thermal cracking gas, and thus, a loss of heat of the thermal cracking gas occurs and the sensible heat of the produced gas is not utilized effectively, and the production efficiency is reduced. Object of the Invention [0007] It is the object of the present invention to substantially overcome or at least ameliorate one or more of the foregoing disadvantages. Summary of the Invention [0008] The present invention provides a production method of a coal gas including a hydrogen gas and a carbon monoxide gas using a coal gasification reactor provided with a lower part reactor vessel having a housing space therein, and an upper part reactor vessel provided on the lower part reactor vessel, wherein the upper part reactor vessel has a penetration hole communicating the housing space of the lower part reactor vessel to the upper part reactor vessel and extending in a vertical direction, the method comprises the steps of: supplying a first coal, oxygen and steam into the lower part reactor vessel so as to produce a high temperature gas by a partial oxidation reaction; supplying a second coal into the upper part reactor vessel while introducing the high temperature gas so as to perform a thermal cracking of the second coal; and adjusting the increase or decrease in a supply amount of the second coal supplying into the upper part reactor vessel so that the temperature of the coal gas discharged from the 4 discharging port of the upper part reactor vessel is controlled at 1000 to 1200'C, wherein the temperature of the coal gas is controlled by supplying the second coal to the upper part reactor vessel and cooling, by endothermic reaction, the high temperature gas which has moved upward from the lower part reactor vessel. [0009] In addition, a production method of methane in another aspect of the present invention performs methanation of the coal gas produced by the production method of a coal gas described above. [0010] According to the production method of coal gas in an embodiment of the present invention, a coal gas containing a small amount of tar can be produced. According to the production method of methane in an embodiment of the present invention, the above coal gas containing a small amount of tar is adopted into a methane producing process; thereby methane can be produced in more high efficiency than a conventional method. BRIEF DESCRIPTION OF THE DRAWINGS [0011] FIG. 1 is a block diagram showing one embodiment of a coal gasification system using a production method of a coal gas of the present invention. FIG. 2 is a vertical sectional view showing one embodiment of a coal gasification reactor of the present invention. FIG. 3 is a graph showing the relationship of the temperature ('C) of a coal gas 5 discharged from a discharging port of thermal cracking part to a conversion rate (% by mass) of carbon in coal which have been converted to tar, in the coal gasification reactor. FIG. 4 is a diagram showing a calculation result of comparison with the production method of the present invention and the conventional production method with respect to a production efficiency when methane is produced from coal. 10 EMBODIMENTS OF THE INVENTION [0012] <Production method of coal gas> The production method of a coal gas of the present invention uses a certain coal 15 gasification reactor provided with a lower part of reactor vessel and an upper part of reactor vessel, and produces a high temperature gas by an partial oxidation reaction by supplying a coal (first coal), oxygen and steam into the lower part of reactor vessel. In addition, an additional coal (second coal) is supplied into the upper part of reactor vessel while introducing the high temperature gas into the upper part of reactor vessel, and the 20 additional coal which has been supplied is subjected to a thermal cracking. According to the above, the present invention discloses a production method of a coal gas including hydrogen gas and carbon monoxide gas. Such production method has a feature in adjusting the increase or decrease in a supply amount of second coal supplying into the upper part reactor vessel in order to 25 control the temperature of the coal gas, which is discharged from the discharging port of the upper part reactor vessel, at I 000 0 C or more, and for the other configurations of the present invention, the configuration used in the conventional production method can be arbitrarily applied. Hereinafter, the production method of a coal gas of the present invention is 5 explained with the reference to the FIG I and FIG 2. [0013] FIG 1 is a block diagram showing one embodiment of a coal gasification system using a production method of a coal gas of the present invention. A coal gasification system 1 of the present embodiment is a plant facility 10 configured to use a coal gasification reactor 4, produce a coal gas containing hydrogen gas and carbon monoxide as the major components from coal as the raw material, and produce products such as methane, methanol, or ammonia eventually from this coal gas. The coal gasification system 1 is provided with a coal crushing and drying unit 2, a coal supplying unit 3, the coal gasification reactor 4, a heat recovering unit 5, a char 15 recovering unit 6, a shift reaction unit 7, a gas refinery unit 8, a chemical synthesis unit 9, and an air separation unit 10. [0014] Generally, coal has a non-uniformed outer diameter and may include more moisture than the desirable amount in accordance with the type of coal. 20 Thus, first, in the coal crushing and drying unit 2, coal is crushed so as to be in a granular shape having 0.01 to 0.15 mm outer diameter, for example. Furthermore, after being dried so as to have predetermined moisture content, the crushed coal is further supplied to the coal supplying unit 3. In addition, after the coal crushing and drying unit 2 until the coal gasification 25 reactor 4, the crushed coal move through the sealed space so that the moisture content of the dried coal is not changed. Subsequently, the coal are pressurized to a predetermined pressure by a carrier gas inside the coal supplying unit 3 in order to achieve a state of the coal capable to supply to the inside of the coal gasification reactor 4, and then, the coal are transferred to 5 the coal gasification reactor 4. In addition, the air separation unit 10 compresses and liquefies air. Using the difference in boiling point, dried oxygen gas, nitrogen gas or the like are separated from the liquefied air. The oxygen gas separated by the air separation unit 10 is supplied to the coal gasification reactor 4. 10 [0015] The coal gasification reactor 4 is an apparatus which is utilized by incorporating as part of the coal gasification system 1 and produces a coal gas including hydrogen gas and carbon monoxide gas as a major component by the partial oxidation reaction of the coal inside the reactor. 15 FIG. 2 is a vertical sectional view showing one embodiment of a coal gasification reactor of the present invention. The coal gasification reactor 4 of the present embodiment is provided with a partial oxidation part (lower part of reactor vessel) 11 formed a housing space 1 Ia therein, and a thermal cracking part (upper part of reactor vessel) 13 provided on (D1 in a 20 direction D) the lower part reactor vessel 11, and formed a penetration hole 12 communicating the housing space lla of the lower part of reactor vessel 11 to the thermal cracking part (upper part of reactor vessel) 13 and extending in a vertical direction D. The coal gasification reactor 4 is formed by heat-resistant bricks or the like. 25 In the coal gasification reactor 4, a pre-heating part 14 is provided under (D2 in the direction D) the partial oxidation part 11. The partial oxidation part 11 and the pre-heating part 14 are in communication in the vertical direction D. A connection part connecting the thermal cracking part 13 and the partial oxidation part 11, and a connection part connecting the partial oxidation part 11 and the pre-heating part 14 are 5 configured to be narrower than the diameters of the thermal cracking part 13, the partial oxidation part 11 and the pre-heating part 14. [0016] As shown in FIG 2, the partial oxidation part 11 is formed substantially in a cylindrical shape extending in vertical direction D. On the inner circumferential surface 10 of the partial oxidation part 11, a plurality of gasification burners 17 is formed in a cylindrical shape extending along a predetermined axis C1. The predetermined axis CI can be tilted downward with respect to the horizontal direction, as shown in FIG. 2. The gasification burners 17 are connected to the coal supplying unit 3, the air separation unit 10, and the heat recovering unit 5 producing steam in a manner to be 15 described later, and the gasification burners can supply coal, oxygen gas and steam (hereinafter, these are describes as "carbon, or the like,") to the partial oxidation part 11 in a predetermined ratio. The gasification burners 17 are arranged so that the height position of them is the same on the inner circumferential surface of the partial oxidation part 11. In addition, the orientation of the gasification burners 17 is arranged so as to be 20 in skew lines with respect to the central axis C2 of the partial oxidation part 11. Furthermore, the orientation of the gasification burners 17 can be tilted downward. In addition, in the outer circumferential surface of the partial oxidation part 11, a cooling device, which is not shown, is provided, and the cooling device can cool the wall surface of the partial oxidation part 11 heated by the partial oxidation reaction of coal. 25 [0017] The thermal cracking part 13 is formed substantially in cylindrical shape which extends in the vertical direction D. In the thermal cracking part 13, a plurality of coal nozzles 18 supplying coal to the thermal cracking part 13 is provided at the middle part of the vertical direction D. 5 The coal nozzles 18 are connected to the coal supplying unit 3. In addition, the number of coal nozzles 18 is not limited and can be any number. If necessary, for example, a steam nozzle supplying steam to the thermal cracking part 13 can be provided under (D2 side in the direction D) the coal nozzles 18. The steam nozzle can be provided by connecting to the heat recovering unit 5, for example. 10 [0018] An edge (discharging port) 12a, which is the upper side (D1 in the direction D) of the penetration hole 12 of the thermal cracking part 13, is connected to the heat recovering unit 5. At the edge 12a, a temperature measurement device 20 measuring the 15 temperature of the coal gas discharged from the edge 12a is provided. [0019] In the pre-heating part 14 of the present embodiment, a predetermined amount of water W is filled, and as described hereafter, the slag flowing down from the partial oxidation unit 11 can be cooled. 20 [0020] When the coal gasification reactor 4 configured as described above is operated, the carbon, or the like, in a granular shape is supplied into the partial oxidation part 11 from the gasification burners 17 in a predetermined flow velocity. Each gasification burner 17 is arranged as above, and thereby the carbon, or the like, supplied from each 25 gasification burner 17 revolve around the center axis C2 of the partial oxidation part 11.

IU In addition, the gasification burners 17 are tilted downward, and thereby the carbon, or the like, supplied from each gasification burner 17 can promote convection of the carbon, or the like, at the lower part of the partial oxidation part 11. By this convection, the carbon, or the like, is not stagnant inside the partial oxidation part 11, and the partial 5 oxidation reaction proceeds well. At this time, inside the partial oxidation part 11 is in high temperature and high pressure. The temperature and pressure inside the partial oxidation part 11 are preferably set to 1300 to 1600 'C and more preferably set to 1300 to 1400 'C, and preferably set to 2 to 4 MPa and more preferably set to 2 to 3 MPa, because the partial 10 oxidation reaction proceeds satisfactorily in these conditions. Coal becomes in high temperature in this environment, and as shown in the chemical equations (1) to (3) below, carbon monoxide gas, carbon dioxide gas, hydrogen gas and slag (ash component) are produced by the thermal cracking, a separation of char from a volatile gas including tar, steam and the like, and a combustion (partial oxidation 15 reaction) of coal. [0021] 2C+0 2 - 2CO (1) C+0 2 - Co 2 (2)

C+H

2 0 - CO+H 2 (3) 20 [0022] The slag produced inside the partial oxidation part 11 is in a molten state, however, some slag adheres to the inner circumferential surface of the partial oxidation part 11 by cooling using the cooling device described above, and the other slag is recovered by flowing down into water W inside the pre-heating part 14 arranged under 25 the partial oxidation part 11 and cooling.

In addition, the high temperature gas (carbon monoxide gas, carbon dioxide gas, hydrogen gas, steam and the like) produced inside the partial oxidation part 11, tar, char or the like, move upward inside the partial oxidation part 11 while swirling, are transferred to the thermal cracking part 13 from the partial oxidation part 11, and move 5 upward inside the thermal cracking part 13. [0023] In the thermal cracking part 13, an additional coal is supplied into the high temperature gas, which moves upward from the partial oxidation part 11, from the coal nozzle 18, and the thermal cracking gas, tar, char and the like are produced by the 10 thermal cracking reaction of this additional coal. Part of the carbon, which is contained in the additional coal supplied to the thermal cracking part 13, reacts with carbon dioxide inside the thermal cracking part 13, and becomes carbon monoxide by the chemical equation (4) shown below. The above described thermal cracking reaction of coal and a gasifying reaction 15 of carbon using carbon dioxide gas are an endothermic reaction, and thus, the high temperature gas moving upward from the partial oxidation part 11 is cooled. [0024] C+C0 2 -- 2CO (4) [0025] 20 At this time, in the present invention, the increase or decrease in supply amount of the additional coal supplying into the thermal cracking part 13 is adjusted, and the temperature of the coal gas discharged from the edge 12a is controlled at 1000'C or more. The temperature of the coal gas discharged from the edge 12a is controlled to be 1200 'C or less as the upper limit value preferably, and is controlled within 1050 to 1150 'C 25 particularly preferably.

I / By controlling the temperature of the coal gas at 1000 'C or more, the coal gas containing a small amount of tar can be produced. When the temperature of the coal gas is controlled at 1200 'C or less, the coal gasification reactor 4 is less likely to damage, and a durability of the coal gasification reactor 4 can be improved. 5 [0026] The temperature of the coal gas discharged from the edge 12a is controlled by adjusting the increase or decrease in supply amount of the additional coal supplying into the thermal cracking part 13. The thermal cracking of coal in the thermal cracking part 13 is an endothermic reaction, and thus, by increasing the amount of supplying the coal, 10 the temperature of the coal gas discharged from the edge 12a can be reduced, and by decreasing the amount of supplying the coal, the temperature of the coal gas discharged from the edge 12a can be increased. [0027] In addition, the pressure and the gas residence time in the thermal cracking part 15 13 is preferably set to be 2 to 4 MPa and is more preferably set to 2 to 3 MPa in pressure, and is preferably set to be 1 to 5 seconds and is more preferably set to 2 to 3 seconds in gas residence time. Therefore, the tar contained in the coal gas can be reduced more. [0028] As shown in FIG 1, the coal gas in high temperature including hydrogen gas and 20 carbon monoxide is transferred to the heat recovering unit 5 from the discharging port of the thermal cracking part 13 together with char, and is supplied to the heat recovering unit 5. In the heat recovering unit 5, steam is produced by exchanging heat between the coal gas transferred from the thermal cracking part 13 and water. This steam is supplied 25 as a raw material, or the like, which is used in the coal crushing and drying unit 2 and the 1.J shift reaction unit 7. The coal gas cooled by the heat recovering unit 5 is supplied to the char recovering unit 6 from the heat recovering unit 5, and the char included in the coal gas is recovered by the char recovering unit 6. 5 The coal gas passed through the char recovering unit 6 is supplied to the shift reaction unit 7. In order to increase the ratio of the hydrogen gas with respect to the carbon monoxide gas in the coal gas to a predetermined value, steam is supplied into the shift reaction unit 7. According to the chemical equation (5) shown below, the carbon monoxide gas in the coal gas is utilized and the hydrogen gas is produced in lieu of the 10 carbon monoxide gas. [0029] CO + H 2 0 - C02 + H 2 (5) [0030] The coal gas adjusted its content ratio of gas components by the shift reaction 15 unit 7 is supplied to the gas refinery unit 8, and the gases including carbon dioxide in the coal gas, or sulfur are recovered. The coal gas refined by the gas refinery unit 8 is supplied to the chemical synthesis unit 9, and methane and methanol, and the like, are produced by a various chemical reactions and the like. 20 [0031] As explained above, according to the production method of the coal gas of the present invention, only a small amount of tar is produced, and there is an effect that the coal gas containing a small amount of tar (for example, a syngas including H 2 , CO and

CH

4 as a major component) can be produced. 25 Tar is produced by the initial thermal cracking reaction of coal that reacts I '-t instantly, is cracked by H 2 , H20, C0 2 , or the like, in the atmosphere gas, and disappears. Therefore, the content of tar in the coal gas is determined by the balance between the production and the disappearance due to cracking. The components of the atmosphere gas, and in addition of this, the temperature affecting the reaction rate can be provided as 5 the factors affecting the disappearance due to the cracking reaction. In addition, in the production of the coal gas using the coal gasification reactor, the producing amount of tar depends on the amount of coal used as a raw material. According to the above, the inventors of the present invention found that by adjusting the increase and decrease in the supply amount of coal supplied into the upper 10 part of reactor vessel when producing the coal gas using the coal gasification reactor, the produced amount of tar is controlled and the temperature of the coal gas discharged from the discharging port of the upper part of reactor vessel can be controlled at 1000 'C or more that only a small amount of tar is produced, and this has led to the completion of the present invention. 15 [0032] In addition, since the production method of the present invention can produce the coal gas containing a small amount of tar, a unit for lightening the produced tar and a unit for recovering tar described in the method in Patent Document 1 are not required. In addition, the production method of the present invention has no decrease in the 20 producing amount of the final product caused by the use of the product gas, and has excellent production efficiency due to the absence of the loss of heat by the cooling of the thermal cracking gas. [0033] <Production method of methane> 25 The production method of methane is a method performing methanation using the coal gas produced by the production method of a coal gas according to the present invention described above. As an embodiment of this, in the coal gasification system 1 shown in FIG 1, the method including the combination of a shift reaction process and a methanation process is provided. 5 By performing methanation of the coal gas, which contains a small amount of tar and is produced by the production method of a coal gas described above, loss of the heat amount is reduced and methane can be produced in higher production efficiency than in the conventional. [0034] 10 The embodiment of the present invention was described in detail with the reference to the drawings, however, the specific configuration is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention. 15 Examples [0035] By using the coal gasification reactor of an embodiment of FIG. 2, methane was produced by a coal gasification system of an embodiment of FIG 1, but methanation was performed by the chemical synthesis unit. The explanation hereinafter uses the same 20 reference numerals shown in FIG 1 and FIG 2. In a coal gasification reactor 4, as shown in FIG 2, a temperature measurement device 20 measuring the temperature of the coal gas discharged from a discharging port (edge 12a) of a thermal cracking part 13 was provided at the edge 12a, and methane was produced. 25 [0036] I %U As a raw material, coal having a 0.15 mm or less outer diameter, containing 5% by mass of moisture content, and containing 70% by mass of carbon in dried coal was used. The coal, oxygen gas and steam supplied into the partial oxidation part 11 from 5 all the gasification burners 17 were supplied so that the supply rate of coal is at 500 (kg/h), the supply rate of oxygen gas is at 300 (Nm 3 /h), the supply rate of steam is supplied at 40 (kg/h), and they are supplied for 100 hours. The temperature and pressure in the partial oxidation part 11 were 1350 'C and 2.45 MPa, and the pressure in the thermal cracking part 13 was 2.45 MPa and the gas 10 residence time was 2 seconds. Furthermore, the processes described later were performed with respect to the coal supplied into the thermal cracking part 13 from all the coal nozzles 18. [0037] The content of tar contained in the coal gas discharged from the discharging port 15 (edge 12a) of the thermal cracking part 13 was measured. The content of tar was measured by extracting a predetermined amount of a part of the produced coal gas from a sampling nozzle disposed at the discharging port (edge 12a) of the thermal cracking part 13, absorbing the tar in an absorbing solution, and then, removing the absorbing solution. 20 By supplying 24 hours the coal supplied into the thermal cracking part 13 from all the coal nozzles 18 at 500 (kg/h), the temperature of the coal gas was controlled at 800 0 C. Similarly, by supplying 24 hours the coal at 200 (kg / h), the temperature of the coal gas was controlled at approximately 1050 'C. 25 Similarly, by supplying 24 hours the coal at 150 (kg / h), the temperature of the 1 / coal gas was controlled at approximately 150 'C. [0038] The methanation in the chemical synthesis unit 9 is performed by setting 3:1 or higher in volume ratio of hydrogen to carbon monoxide in the coal gas in the shift 5 reaction unit 7 and the gas refinery unit 8, which are the upstream process of the chemical synthesis unit 9, and carrying out the reaction described in the following chemical equation, and methane was produced. CO+3H 2 -> CH 4

+H

2 0 [0039] 10 FIG. 3 is a graph showing the relationship of the temperature ('C) of the coal gas discharged from a discharging port (edge 12a) of thermal cracking part 13 to a conversion rate (% by mass) of carbon in coal which have been converted to tar, in the coal gasification reactor 4. From the result of FIG. 3, the result shows that the conversion rate of which 15 carbon in the coal gas is converted to tar was reduced significantly to 0.3% by mass from 6.9% by mass, when the temperature of the coal gas is changed to 1150 'C from 800 'C. That is, according to the production method of the present invention, it was confirmed that a coal gas containing a small amount of tar can produced. [0040] 20 FIG. 4 is a diagram showing a calculation result of comparison with the production method of the present invention and the conventional production method (that is, the conventional production method performs only a partial oxidation reaction using a general gas flow bed type gasification reactor) with respect to a production efficiency when methane is produced from coal. 25 As a general gas flow bed type gasification reactor, by referring to the Shell 10 process having the highest coal-gasifying efficiency as the gas flow bed type gasification reactor, which is currently commercialized, the coal gasifying efficiency was calculated as 8 0 % (at heat amount basis). In the production method of the present invention, production of methane was 5 performed by controlling the temperature of the coal gas discharged from a discharging port (edge 12a) of a thermal cracking part 13 at 1100 'C. In FIG 4, the "thermal cracking gasification" includes both of the partial oxidation reaction in the partial oxidation part 11 of the coal gasification reactor 4 and the thermal cracking in the thermal cracking part 13. 10 The numbers shown below the compounds indicate the heating value, and when the heating value of the coal of the raw material is set to be 1.00, for example, the present invention shows that the reaction efficiency (q) of the thermal cracking gasification is 8 5 %, that is, 15% is the heat loss. In addition, 73% of the heating value is converted to

CO+H

2 , and the remaining 12% of the heating value is converted to CH 4 . 15 [0041] In FIG 4, in the production method of the present invention, when the thermal cracking gasification of coal is performed, in 85% of the reaction efficiency (i), CO+H 2 having a heat value of 0.73 and CH 4 having a heat value of 0.12 as the coal gas were produced from coal having a heat value of 1.00. 20 Then, when methanation of the coal gas is performed, in 74% of the reaction efficiency (q), CH 4 having a heat value of 0.54 was produced from CO+H 2 having a heat value of 0.73. By adding the CH 4 having a heat value of 0.12 obtained by performing the thermal cracking gasification, CH 4 having a heat value of 0.66 in total amount was produced from coal having a heat value of 1.00. 25 [0042] 17 In a conventional production method, when gasification (partial oxidation) of coal is performed, in 80% of the reaction efficiency (r), CO+H 2 having a heat value of 0.80 was produced from coal having a heat value of 1.00. Then, when methanation of the coal gas is performed, in 74% of the reaction 5 efficiency (q), CH 4 having a heat value of 0.60 was produced from CO+H 2 having a heat value of 0.80, and CH 4 having a heat value of 0.60 was produced from coal having a heat value of 1.00. [0043] From the comparison with the production method of the present invention and 10 the conventional production method (that is, the conventional production method performs only a partial oxidation reaction using a general gas flow bed type gasification reactor), by comparing the production method of the present invention to the conventional production method, the present invention shows that the loss of the heat amount is reduced and since methane produced by performing the thermal cracking 15 gasification is not subjected to loss of production in chemical synthesis, the efficiency of producing methane from coal is 10% higher than the conventional method (the present invention has a higher heating value than the production method of methane using a general gas flow bed type gasification reactor. There is a difference of 0.06 in heat value). That is, from the result of FIG. 4, according to the production method of the 20 present invention, it was confirmed that the present invention can produce methane in higher production efficiency than that of the production method of methane using a general gas flow bed type gasification reactor. Description of Reference Signs 25 [0044] 4: coal gasification reactor 11: partial oxidation part (lower part of reactor vessel) 12: penetration hole 12a: edge 5 13: thermal cracking part (upper part of reactor vessel) 17: gasification burner 18: coal nozzle 20: temperature measurement device

Claims (2)

1. A production method of a coal gas including a hydrogen gas and a carbon monoxide gas using a coal gasification reactor provided with a lower part reactor vessel having a housing space therein, and an upper part reactor vessel provided on the lower part reactor vessel, wherein the upper part reactor vessel has a penetration hole communicating the housing space of the lower part reactor vessel to the upper part reactor vessel and extending in a vertical direction, the method comprises the steps of: supplying a first coal, oxygen and steam into the lower part reactor vessel so as to produce a high temperature gas by a partial oxidation reaction; supplying a second coal into the upper part reactor vessel while introducing the high temperature gas so as to perform a thermal cracking of the second coal; and adjusting the increase or decrease in a supply amount of the second coal supplying into the upper part reactor vessel so that the temperature of the coal gas discharged from the discharging port of the upper part reactor vessel is controlled at 1000 to 1200'C, wherein the temperature of the coal gas is controlled by supplying the second coal to the upper part reactor vessel and cooling, by endothermic reaction, the high temperature gas which has moved upward from the lower part reactor vessel.

2. A production method of methane comprises the step of: performing methanation of the coal gas produced by the production method of a coal gas according to Claim 1. Nippon Steel & Sumikin Engineering Co., Ltd. Patent Attorneys for the Applicant SPRUSON & FERGUSON