AU2011241502A1

AU2011241502A1 - Method for thermally decomposing and gasifying coal and apparatus for thermally decomposing and gasifying coal

Info

Publication number: AU2011241502A1
Application number: AU2011241502A
Authority: AU
Inventors: Masumi Itonaga; Masato Kageyama; Katsushi Kosuge; Hiroyuki Kozuru; Yasuki Namiki; Suguru Takeda; Hideaki Yabe
Original assignee: Nippon Steel and Sumikin Engineering Co Ltd
Current assignee: Nippon Steel Engineering Co Ltd
Priority date: 2010-04-16
Filing date: 2011-04-15
Publication date: 2012-12-06
Anticipated expiration: 2031-04-15
Also published as: JP5450800B2; JPWO2011129434A1; CN102939361B; AU2011241502B2; WO2011129434A1; CN102939361A

Abstract

Disclosed is a thermal decomposition coal gasification method using an upper/lower chamber two-level gas current layer reactor (20) comprising an upper level with a cylindrical gasification furnace and a lower level with a cylindrical reforming furnace (1) connected by an enlarged diameter portion throat (3) therebetween, wherein at least coal and an oxygen-containing gas are introduced into the gasification furnace, gasified gas is generated by partial oxidisation of the coal, the gasified gas is introduced into the reforming furnace (1), at least coal is input into the reforming furnace (1), the coal added to the reforming furnace is thermally decomposed by the sensible heat of the gasified gas and so generates a generated gas containing at least hydrogen gas and carbon monoxide gas. The coal input into the gasification furnace is input conveyed by air currents in a circumferential direction so as to create a rotational flow inside the gasification furnace, and the coal input into the reforming furnace (1) is input conveyed by air currents in a circumferential direction opposite to the direction of rotational flow in the gasification furnace.

Description

Il DESCRIPTION METHOD FOR THERMALLY DECOMPOSING AND GASIFYING COAL AND APPARATUS FOR THERMALLY DECOMPOSING AND GASIFYING COAL 5 TECHNICAL FIELD [0001] The present invention relates to a method for thermally decomposing and gasifying coal and an apparatus for thermally decomposing and gasifying coal in which 10 coal is rapidly gasified and thermally decomposed in an entrained flow to produce a product gas containing at least hydrogen gas and carbon monoxide gas. The present application claims priority on Japanese Patent Application No. 2010-95495 filed on April 16, 2010, the content of which is incorporated herein by reference. 15 BACKGROUND ART [0002] There have been so far proposed several processes for thermally decomposing coal in which coal is heated at high temperatures and is thermally decomposed to directly 20 produce a fuel gas containing hydrocarbon gas such as methane and oil such as benzene, toluene and xylene (BTX). [0003] A method for thermally decomposing coal is disclosed in Patent Document I described below. In the method for thermally decomposing coal, a high-temperature gas 25 is produced during gasification of coal and a carbonaceous material by using oxygen, and 2 coal is blown into the high-temperature gas; and thereby, the coal is subjected to rapid heating and thermal decomposition reaction in an entrained flow. In particular, BTX can be obtained at a high efficiency by this method for thermally decomposing coal. Furthermore, with regard to the method for thermally decomposing coal, the initial cost of 5 equipment can be reduced. Furthermore, the method for thermally decomposing coal eliminates a need for supplying heat and has excellent heat efficiency. The heat efficiency can be calculated by using the formula (1) described below. Heat efficiency = (heat value of product gas + heat value of product oil) / (heat value of supplied coal - heat value of produced char) ... (1) 10 [0004] In addition, a coal hydro-pyrolysis method is disclosed in Patent Document 2 described below. In the coal hydro-pyrolysis method, a high-temperature gas is produced during gasification of coal and a carbonaceous material by using oxygen, and coal and hydrogen are blown into the high-temperature gas; and thereby, the coal is 15 subjected to rapid heating and hydro-pyrolysis reaction in an entrained flow. Light oil and a fuel gas such as methane can be obtained at a high efficiency by this method for thermally decomposing coal. PRIOR ART DOCUMENT 20 Patent Document [0005] Patent Document 1: Japanese Unexamined Patent Application, First Publication No. H5-295371 Patent Document 2: Japanese Unexamined Patent Application, First Publication 25 No. 2004-217868 3 Patent Document 3: Japanese Unexamined Patent Application, First Publication No. S61-246287 DISCLOSURE OF THE INVENTION 5 Problems to be Solved by the Invention [0006] In the processes proposed in Patent Documents I and 2, an apparatus is used which includes a reactor having two tiers of upper and lower chambers. In a gasification furnace which is a lower chamber of the reactor, it is desired to lengthen the particle 10 retention time inside the furnace in order to increase the reaction rate of coal to be supplied and char (coal residue not yet gasified and thermally decomposed residue). Thus, burners of supplying coal are installed on the gasification furnace at a certain angle so that the coal to be supplied and the char form a rotational flow inside the furnace. [0007] 15 However, the rotational flow formed in the gasification furnace also flows in a reforming furnace which is an upper chamber of the reactor while keeping the rotational flow. Therefore, when coal is blown into the reforming furnace, the supplied coal particles flow in the vicinity of a furnace wall together with the rotational flow. As a result, the coal particles adhere on the furnace wall of the reforming furnace. This may 20 result in operation troubles. Furthermore, since the rotational flow is kept even in the reforming furnace as described above, a variation occurs in the particle concentration of the coal supplied into the reforming furnace. Therefore, the temperature rise of the particles becomes non-uniform at portions in which the particle concentration is high. As a result, reactions 25 may proceed in a non-uniform manner.

4 In Patent Document 2, it is thought that coal is supplied so as to rotate in the same direction as the rotational flow in the gasification furnace, for the purpose of lengthening the retention time of coal particles which are supplied into the reforming furnace. Furthermore, in Patent Document 3 described above, an entrained-bed coal 5 gasification furnace is disclosed in which the rotational diameter of a two-tiered fuel supplying unit is changed. In the invention of Patent Document 3, the gasification of coal is conducted not by a reforming furnace which carries out thermal decomposition but by a gasification furnace. Therefore, the invention of Patent Document 1 is different from the invention of Patent Document 2 in its reactions inside the reactor. That is, since 10 thermal decomposition of coal is carried out by using no oxygen, coal tar is generated together with gases such as hydrogen, carbon monoxide, methane, and the like. Therefore, in the inventions of Patent Documents I and 2, carbonaceous substances derived from coal tar will easily adhere inside the reactor. On the other hand, in the invention of Patent Document 3, since coal is decomposed into carbon monoxide and the 15 like by using oxygen, no coal tar will occur. Thus, a problem of adhesion of carbonaceous substances is not found. [0008] The present invention aims to provide a method for thermally decomposing and gasifying coal and an apparatus for thermally decomposing and gasifying coal which are 20 capable of suppressing operation troubles and non-uniform reactions inside a reforming furnace. Means for Solving the Problems [0009] 25 A method for thermally decomposing and gasifying coal of the present invention 5 includes: using an entrained flow reactor having two tiers of upper and lower chambers which includes a cylindrical gasification furnace as the lower chamber, a cylindrical reforming furnace as the upper chamber, and a throat which is an enlarged diameter portion connecting the furnaces; supplying at least coal and an oxygen-containing gas into 5 the gasification furnace; partially oxidizing the coal so as to produce a gasified gas; introducing the gasified gas into the reforming furnace; supplying at least coal into the reforming furnace; and thermally decomposing the coal which has been supplied into the reforming furnace by using sensible heat of the gasified gas, thereby producing a product gas which contains at least hydrogen gas and carbon monoxide gas. The coal to be 10 supplied into the gasification furnace is supplied by pneumatic conveyance so as to form a rotational flow in a circumferential direction inside the gasification furnace. The coal to be supplied into the reforming furnace is supplied by pneumatic conveyance in a circumferential direction which is opposite to the rotational flow of the coal to be supplied into the gasification furnace. 15 That is, the method for thermally decomposing and gasifying coal includes: a step in which coal is supplied together with an oxygen-containing gas into the gasification furnace so that a gas which transfers the coal forms a rotational flow in a circumferential direction inside the gasification furnace; a step in which the coal supplied into the gasification furnace is partially oxidized so as to produce a gasified gas; a step in which 20 coal is supplied into a reforming furnace communicatively connected to the gasification furnace so that a gas which transfers the coal flows inside the reforming furnace in a direction opposite to the flow of the gas inside the gasification furnace; and a step in which the coal supplied into the reforming furnace is thermally decomposed by the gasified gas which flows into the reforming furnace from the gasification furnace so as to 25 produce a gas which contains hydrogen gas and carbon monoxide gas.

6 [0010] Two or more sites may be provided at which the coal is supplied in the reforming furnace and all of angles of supplying the coal from the two or more sites with respect to a furnace wall of the reforming furnace may be set to be a same angle. 5 [0011] The two or more sites of supplying the coal in the reforming furnace may be positioned so as to be equally spaced with each other in a circumferential direction on the furnace wall of the reforming furnace. [0012] 10 Apart from the two or more sites of supplying the coal in the reforming furnace, other two or more sites may be further provided at which the coal is supplied into the reforming furnace by pneumatic conveyance in a circumferential direction opposite to the rotational flow of the coal to be supplied into the gasification furnace, and all of angles of supplying the coal from the other two or more sites with respect to the furnace wall of the 15 reforming furnace may be set to be a same angle, and the angle may be different from the angle of supplying the coal from the two or more sites. That is, apart from the two or more sites of supplying the coal in the reforming furnace, other two or more sites may be further provided, and coal may be supplied into the reforming furnace from the other two or more sites of supplying the coal by pneumatic 20 conveyance in a circumferential direction which is opposite to the rotational flow of the coal to be supplied into the gasification furnace. All of angles of supplying the coal from the other two or more sites with respect to the furnace wall of the reforming furnace may be set to be a same angle, and the angle may be different from the angle of supplying the coal from the two or more sites. 25 [0013] 7 The two or more sites of supplying the coal and the other two or more sites of supplying the coal in the reforming furnace may be alternately positioned in a circumferential direction. [0014] 5 An apparatus for thermally decomposing and gasifying coal of the present invention is an apparatus used in the method for thermally decomposing and gasifying coal. The apparatus includes an entrained flow reactor having two tiers of upper and lower chambers which includes a cylindrical gasification furnace as the lower chamber, and a cylindrical reforming furnace as the upper chamber. The gasification furnace 10 includes nozzles of supplying at least coal into the gasification furnace by pneumatic conveyance, and nozzles of supplying an oxygen-containing gas into the gasification furnace. The nozzles of supplying at least the coal into the gasification furnace by pneumatic conveyance are arranged so that the coal to be supplied into the gasification furnace forms a rotational flow in a circumferential direction inside the gasification 15 furnace. The reforming furnace includes nozzles of supplying coal into the reforming furnace by pneumatic conveyance. The nozzles of supplying the coal into the reforming furnace by pneumatic conveyance are arranged so that the coal is supplied in a circumferential direction opposite to the rotational flow of the coal to be supplied into the gasification furnace. 20 Effects of the Invention [0015] According to the method for thermally decomposing and gasifying coal and the apparatus for thermally decomposing and gasifying coal in the present invention, it is 25 possible to enhance the dispersity of the supplied coal inside the reforming furnace and to 8 suppress operation troubles and non-uniform reactions inside the reforming furnace. BRIEF DESCRIPTION OF THE DRAWINGS [0016] 5 Fig. 1 is a schematic diagram which shows an apparatus for thermally decomposing and gasifying coal according to one embodiment of the present invention. Fig. 2 is a cross-sectional schematic diagram which shows a reforming furnace of an entrained flow reactor in the apparatus for thermally decomposing and gasifying coal shown in Fig. 1. 10 Fig. 3 is a cross-sectional schematic diagram of the reforming furnace which shows an example of installing nozzles of blowing reformed-coal having two types of angles. Fig. 4 is a cross-sectional schematic diagram of the reforming furnace which shows a configuration of installing nozzles of blowing reformed-coal in Comparative 15 Example 1. BEST MODE FOR CARRYING OUT THE INVENTION [0017] Hereinafter, an explanation will be made for the apparatus for thermally 20 decomposing and gasifying coal according to one embodiment of the present invention while referring to the drawings. As shown in Fig. 1, an apparatus for thermally decomposing and gasifying coal 20 includes an entrained flow reactor 21 (hereinafter referred to as an entrained flow reactor 21 or simply referred to as a reactor 21) including a gasification furnace 2 on the upstream 25 side and a reforming furnace I on the downstream side.

9 [0018] The gasification furnace 2 gasifies gasified coal 9 to be supplied by using oxygen 12 as an oxidizing agent (gasifying agent) so as to produce a gasified gas 14 which mainly includes carbon monoxide, carbon dioxide, hydrogen and steam. Here, in the 5 gasification furnace 2, it is necessary to melt ash contained in the gasified coal 9 and to remove the ash from the gasification furnace 2. Therefore, a temperature inside the gasification furnace 2 is required to be higher than the melting point of the ash. As a result, a temperature of the gasified gas 14 introduced into the reforming furnace 1 from the gasification furnace 2 is also high. Thus, reformed coal 10 is supplied into the 10 gasified gas 14 in the reforming furnace 1; and thereby, a temperature of the reformed coal 10 is raised, and thermal decomposition reactions occur. As a result, it is possible to obtain a product 16 including a product gas which contains at least hydrogen gas and carbon monoxide gas. [0019] 15 The above-described entrained flow reactor 21 has two tiers of upper and lower chambers which includes the gasification furnace 2 as the lower chamber and the reforming furnace I as the upper chamber. Furthermore, the entrained flow reactor 21 has a so-called throat structure in which the gasification furnace 2 and the reforming furnace I are connected via a throat 3 that is enlarged in diameter from the gasification 20 furnace 2 smaller in diameter to the reforming furnace 1. As described above, since the entrained flow reactor has two tiers of upper and lower chambers, it is possible to completely separate the gasification furnace 2 from the reforming furnace 1, and the gasification furnace 2 is a part where coal is gasified, and the reforming furnace 1 is a part where thermal decomposition is carried out. Thereby, it is possible to freely set 25 operation conditions of individual parts.

10 That is, in the entrained flow reactor 21, such a structure is provided that the throat 3 gradually enlarged in diameter after once being narrowed is placed into a gas flowing channel so as to increase a flow rate partially. Thereby, coal particles (reformed coal 10) and the like which are supplied into the reforming furnace I (the upper chamber) 5 are prevented from falling down into the gasification furnace 2 (the lower chamber). As a result, it is possible to set reaction conditions at each chamber independently. Each of the gasification furnace 2, the reforming furnace 1 and the throat 3 has a cylindrical structure, and the horizontal cross section of which is circular. [0020] 10 Here, the gasified coal 9 inside the gasification furnace 2 is partially oxidized; and thereby, the temperature of the gasified coal 9 becomes high. As a result, ash contained in the gasified coal 9 turns into a melted slag 15. Therefore, it is preferable that a slag tap 6 of discharging the slag 15 and a water tank 8 for catching the slag 15 are installed at a lower part of the gasification furnace 2. 15 It is also preferable that a boiler pipe 17 is used on a furnace wall of the gasification furnace 2 so that the melted slag 15 is adhered on the furnace wall to protect the wall surface. [0021] Furthermore, one or more of gasification burners 5 which supply the gasified coal 20 9 together with an oxygen-containing gas 11 as an oxidizing agent for partially oxidizing the gasified coal 9 are installed in the gasification furnace 2. As the oxygen-containing gas 11, oxygen 12 or a mixture of the oxygen 12 and steam 13 may be adopted. Then, the gasified coal 9 and the oxygen-containing gas 11 are blown into the gasification furnace 2 by using the gasification burner 5 and rapidly mixed with each 25 other.

[0022] It is preferable that carbon and hydrogen components in hydrocarbon contained in the gasified coal 9 to be supplied are converted to CO and H 2 as much as possible to increase a gasification conversion rate in the gasification furnace 2. Therefore, before 5 volatile components occurring from the gasified coal 9 turn into soot, the gasified coal 9 is required to be quickly mixed with the oxygen-containing gas I I so as to react the volatile components with the oxygen-containing gas 11. Thus, it is preferable that, for example, a double pipe structure or the like is used as the gasification burner 5 to supply the gasified coal 9 and the oxygen-containing gas 11 from the same position. 10 [0023] In the case where the double pipe structure is not used to supply the oxygen-containing gas 11, the oxygen-containing gas 11 is preferably blown into a site (portion) inside the gasification furnace 2 where the concentration of coal particles is high. Therefore, it is preferable that a supply nozzle of supplying the oxygen-containing gas 11 15 is positioned at the same height as a supply nozzle of supplying the gasified coal 9 so as to supply the oxygen-containing gas 11 and the gasified coal 9 at the same level. As a result, it is possible to prevent the gasification conversion rate of the gasified coal 9 from being reduced in even in the case where a coal supply port is different from an oxygen-containing gas supply port. 20 Furthermore, the gasified coal 9 is transferred by using a carrier gas which is different from the oxygen-containing gas 11; and thereby, the gasified coal 9 is supplied into the gasification furnace 2. As the carrier gas, a non-oxidizing gas such as nitrogen gas or a gas generated in a process may be used; however, the carrier gas is not restricted thereto. 25 [0024] 12 In the present embodiment, the gasification burner 5 is installed inside the gasification furnace 2 at an angle so that a rotational flow of the gasified coal 9 is formed in a circumferential direction. Thereby, it is possible to secure retention time of the gasified coal 9 inside the gasification furnace 2; and as a result, it is possible increase the 5 gasification conversion rate. It is preferable that two or more gasification burners 5 are installed so as to form a stable rotational flow inside the gasification furnace 2. It is also preferable that the gasification burner 5 is positioned at a lower portion of the gasification furnace 2 in order to stably discharge the slag 15 generated in the gasification furnace 2. Furthermore, it is 10 preferable that, in order to stably discharge the slag 15 generated in the gasification furnace 2, the gasification burner 5 faces a tangential direction of a virtual circle which has a diameter of 1/10 to 2/3 of the diameter of the gasification furnace 2 (which has the same central axis as the gasification furnace 2). [0025] 15 Pressure and temperature during operation of the gasification furnace 2 are kept, for example, in a range of 0.1 MPa to 20 MPa and in a range of 1300"C to 1700*C, respectively. The pressure is adjusted in accordance with the pressure of the reforming furnace 1. As described above, the gasified gas 14 generated in the gasification furnace 2 is 20 fed to the reforming furnace I via the throat 3. [0026] In the reforming furnace 1, the reformed coal 10 is supplied to cause thermal decomposition reactions of the coal. Due to the thermal decomposition reactions which occur, a product gas, char, coal tar, and the like are produced as products 16 from the coal. 25 The product gas can be used as a fuel or a chemical material, the char can be used as a 13 solid fuel, and the coal tar can be used as a chemical material or a fuel, respectively. The reformed coal 10 is supplied into the reforming furnace 1, while being transferred by using a carrier gas. At this time, it is possible to produce the products 16 by subjecting the reformed coal 10 to thermal decomposition reactions even in the case 5 where only the reformed coal 10 is supplied into the reforming furnace I while being transferred by using the carrier gas. Furthermore, it is possible to change properties and quantities of the product gas and the coal tar to be produced by supplying one or more of hydrogen, steam, and oxygen together with the reformed coal 10. [0027] 10 Pressure and temperature during operation of the reforming furnace I are kept in a range of 0.1 MPa to 20 MPa and in a range of 500'C to 1200 0 C, respectively. Since the reforming furnace I is connected to the gasification furnace 2 vertically via the throat 3, the pressures of both of the furnaces are substantially equal during operation. The pressure of the reforming furnace 1 during operation is preferably in a range 15 of I MPa to 3 MPa depending on application of the productgas. That is, in the case where the pressure of the reforming furnace I during operation is excessively low, it is necessary to increase a furnace volume for securing gas retention time inside the gasification furnace 2. As a result, since a surface area inside the gasification furnace 2 is increased, a quantity of heat dissipation is increased. Thus, an excessively low 20 pressure of the reforming furnace 1 during operation is not preferable. Furthermore, in the case where a pressure of the reforming furnace 1 during operation is excessively high, the cost of manufacturing equipment becomes high. In the case where operation is done on the high pressure side, that is, the pressure of the reforming furnace 1 during operation is high, gasification and hydrogenation can also be proceeded by supplying steam together 25 with the reformed coal 10 into the reforming furnace 1.

14 [0028] It is preferable that the reforming furnace 1 is operated under the following temperature conditions. That is, in the case where, among the products 16, substances to be recovered are mainly a product gas and coal tar, relatively low temperature conditions 5 in a range of 500'C to 800 C are preferable. Furthermore, in the case where the recovered substance is mainly a product gas, relatively high temperature conditions in a range of 800'C to 1200'C are preferable. Furthermore, in the case where the recovered substance is mainly a product gas, it is preferable that a modifying agent such as steam or hydrogen is added to the reforming 10 furnace I and a modifying agent such as steam is added to the gasification furnace 2, so as to accelerate gasification reactions inside the reforming furnace 1. It is also preferable that char generated in the reforming furnace I is supplied as a fuel of the gasification furnace 2 together with the gasified coal 9 so as to recycle the char. [0029] 15 Here, a rotational flow formed in the gasification furnace 2 flows and ascends in the reforming furnace 1 while maintaining the rotation. Therefore, in the case where the reformed coal 10 is simply supplied into the reforming furnace 1 in a direction perpendicular to a furnace wall la, and in the case where the reformed coal 10 is supplied in the same direction as the rotational flow, particles of the reformed coal 10 flow in the 20 rotational flow; and thereby, a region exists where the coal concentration is partially high. In this case, a temperature of the reformed coal 10 rises in a non-uniform manner; and thereby, thermally decomposed products can not be obtained stably. Furthermore, since the regions where the concentration of particles of the reformed coal 10 is high exist at or in the vicinity of the furnace wall la of the reforming furnace 1, there is a fear that 25 particles of which the temperature is not raised sufficiently may adhere on the furnace 15 wall I a to form adhesions. [0030] Therefore, as shown in Fig. 2, nozzles 4 of blowing the reformed coal are installed at a supply (input) angle so as to oppose the rotational flow (arrow F indicated in Fig. 2) in 5 the gasification furnace 2. Thereby, inventors have found that it is possible to achieve the uniformity in the concentration of particles in a radial direction of the reforming furnace I inside the reforming furnace 1, that is, the concentration of particles at each position along the radial direction of the reforming furnace 1. That is, in the reforming furnace 1, the nozzles 4 are installed at a supply angle 10 such that the reformed coal 10 is supplied into the reforming furnace 1 by pneumatic conveyance in a circumferential direction which is opposite to the rotational flow of the gasified gas 14 introduced from the gasification furnace 2 via the throat 3. [0031] Here, when the reforming furnace I is observed from above, the supply angle 15 means a horizontal angle (angle a indicated in Fig. 2) between a nozzle axis line 22 of the nozzle 4 and a virtual line 23. The nozzle axis line 22 of the nozzle 4 extends along a direction at which the reformed coal 10 is supplied from the nozzle 4 of blowing the reformed coal, and the virtual line 23 is drawn from a position of the furnace wall la of the reforming furnace I at which the nozzle is installed to the central axis 0 of the 20 reforming furnace. [0032] Regarding the number of the nozzles 4 and the supply angle, it is preferable that two or more nozzles 4 are installed at a symmetrical position at the same angle so that coal will not flow in a non-uniform manner inside the reforming furnace 1. That is, it is 25 preferable that a plurality of nozzles 4 are arranged on the furnace wall I a of the reforming 16 furnace I with an equal space kept in a circumferential direction. Furthermore, it is preferable that horizontal angles of the nozzles 4 are the same and the nozzle axis line 22 of each of the nozzles 4 is along in a tangential direction of the same virtual circle 24 having the same central axis as the central axis 0 of the reforming 5 furnace. In the case where the horizontal angle is excessively small, the effect becomes small. In the case where the horizontal angle is excessively large, there is a fear that the reformed coal 10 of which the temperature is not raised yet collides against the furnace wall I a of the reforming furnace 1. Therefore, the horizontal angle is preferably at a degree such that the diameter of the virtual circle 24 is 1/5 to 2/3 of the inner diameter of 10 the reforming furnace 1. A perpendicular angle which is an angle with respect to a horizontal plane of the nozzle axis line 22 of the nozzle 4 of blowing the reformed coal may also be equal in all the nozzles 4. [0033] 15 In the case where a flow rate of blowing the reformed coal 10 is excessively large, it is necessary to decrease the diameter of the nozzle 4 of blowing the reformed coal when a pressure during operation becomes high. Therefore, there is a fear that the nozzle 4 may be easily clogged. Accordingly, it is not preferable to blow the reformed coal 10 at an excessively high flow rate. Thus, it is preferable that the flow rate is set to be 20 substantially equal to a flow rate at which the gasified coal 9 is pneumatically transferred in the gasification furnace 2, that is, in a range of several meters/sec to 20 meters/sec. [0034] As described above, according to the method for thermally decomposing and gasifying coal and the apparatus for thermally decomposing and gasifying coal 20 in the 25 present embodiment, the reformed coal 10 is supplied by pneumatic conveyance in a 17 circumferential direction which is opposite to a rotational flow of the gasified coal 9 to be supplied into the gasification furnace 2. Thus, the rotational flow of the gasified gas 14 introduced from the gasification furnace 2 is offset inside the reforming furnace 1. Therefore, it is possible to prevent the reformed coal 10 from flowing in the vicinity of the 5 furnace wall la of the reforming furnace 1 in the rotational flow inside the reforming furnace 1. Thereby, the variation of the concentration of the reformed coal 10 is less likely to occur inside the reforming furnace 1, and the dispersity of the reformed coal 10 can be increased. As described above, it is possible to suppress adhesion of coal particles on the 10 furnace wall Ia of the reforming furnace 1; and thereby, operation troubles can be prevented. It is also possible to secure uniformity of reactions inside the reforming furnace 1. [0035] The concentration of particles to be supplied into the reforming furnace 1 at a 15 higher pressure during operation of the reforming furnace I becomes higher than that at a lower pressure during operation. Therefore, since the rotational flow in the gasification furnace 2 affects, it is more likely that regions are formed in which the concentration of particles is higher in the reforming furnace 1. Thus, when the pressure during operation is higher, more apparent effects are provided in the present invention. 20 In the case where the size of the reactor 21 is increased, the diameter of the reforming furnace I is increased. Thus, the reformed coal 10 which is blown into is poorly mixed with the gasified gas 14, and the concentration of particles is more likely to be non-uniform. Therefore, the effects of the present invention are more apparent in the reactor 21 larger in size and greater in processing quantity. 25 [0036] 18 The technical scope of the present invention shall not be restricted to the above embodiment and may be modified in various ways within a scope not departing from the features of the present invention. [0037] 5 For example, as shown in Fig. 3, two or more supply angles a, P of the nozzles 4A, 4B of blowing the reformed coal may be set in the reforming furnace 1. That is, in the reforming furnace I shown in Fig. 3, among the nozzles 4A and 4B of blowing the reformed coal, all of supply angles of a plurality of the first nozzles 4A are set to be the same supply angle a. Among the nozzles 4A and 4B of blowing the reformed coal, all of 10 supply angles of a plurality of the second nozzles 4B are set to be the same supply angle p, and the supply angle p is different from the supply angle a. As a result, virtual circles 24A and 24B to which the respective nozzle axis lines 22A and 22B of the plurality of the first nozzles 4A and the plurality of the second nozzles 4B correspond are different in diameter. In this case, the dispersity of the reformed coal 10 can be further improved 15 inside the reforming furnace 1. Therefore, as shown in Fig. 3, installation of the nozzles 4A, 4B is in particular preferable, for example, in the case where the diameter of the reforming furnace 1 is large. [0038] In the reforming furnace I shown in Fig. 3, the first nozzles 4A and the second 20 nozzles 4B are alternately installed in a circumferential direction. Thereby, the reformed coal 10 is prevented from flowing in a non-uniform manner inside the reforming furnace 1; and as a result, the dsiperisty of the reformed coal 10 can be further improved inside the reforming furnace 1. In the illustrated example, for example, a supply rate of the reformed coal 10 from the first nozzles 4A may be set to a value different from a supply 25 rate of the reformed coal 10 from the second nozzles 4B.

19 [0039] Furthermore, in the above-described embodiment, the reformed coal 10 is supplied into the reforming furnace I by pneumatic conveyance only in a circumferential direction which is opposite to the rotational flow of the gasified gas 14 introduced via the 5 throat 3 from the gasification furnace 2. However, the present invention shall not be restricted thereto. In the method for thermally decomposing and gasifying coal in the present invention, it is only necessary to supply the reformed coal 10 in a circumferential direction which is opposite to the rotational flow of the gasified gas 14. Thus, it is acceptable that the reformed coal 10 is further supplied, for example, in a circumferential 10 direction which is the same direction as the rotational flow. [0040] In addition, constituents of the embodiment may be replaced with known constituents, whenever necessary, within a scope not departing from the features of the present invention. In addition, the above-described modified examples may be combined 15 appropriately. EXAMPLES [0041] (Example 1) 20 Examples are shown below in which the apparatus described in Fig. I was used to carry out gasification and thermal decomposition. A gasification furnace 2 was operated at a pressure of 2.5 MPa and at a temperature of 1450 0 C, while a reforming furnace I was operated at a pressure of 2.5 MPa and at a temperature of II 00*C. 25 Gasified coal 9 ground to have the average particle size of 40 ptm was supplied 20 into the gasification furnace 2 by pneumatic conveyance with the use of nitrogen gas. A quantity of the gasified coal 9 was 500 kg/h (coal ash of 2.7%, volatile components of 45%, and moisture content of 5%). Furthermore, a quantity of steam 13 supplied into the gasification furnace 2 was 50 kg/h, and a supplied quantity of oxygen 12 was 310 Nm 3 /h. 5 In addition, reformed coal 10 was supplied at a quantity of 162 kg/h into the reforming furnace I by pneumatic conveyance with the use of nitrogen gas. Pneumatic conveyance was carried out at a rate of 10 m/sec. [0042] In the gasification furnace 2, the gasified coal 9 together with steam 13 and 10 oxygen 12 as an oxygen-containing gas 11 were supplied in four directions which were tangential directions of a virtual circle that had a diameter of 1/3 of a diameter of the gasification furnace; and thereby, a rotational flow was formed. The gasified coal 9, the steam 13 and the oxygen 12 were supplied by using double pipe burners. The gasified coal 9 and a carrier gas flowed inside the double pipe, that is, an inner tube of the double 15 pipe, while a mixture of the steam 13 and the oxygen 12 flowed outside the double pipe, that is, between the inner tube and an outer tube of the double pipe. In addition, in the reforming furnace 1, nozzles 4 of blowing the reformed coal as shown in Fig. 2 were used to supply the reformed coal 10 in four directions which were tangential directions of a virtual circle 24 that had a diameter of 1/2 of a diameter of the 20 reforming furnace; and thereby, a rotational flow was formed. [0043] As a result, a quantity of the gasified gas 14 at a throat 3, that is, an outlet of the gasification furnace 2, was 1134 Nm 3 /h, and a heat value of the gasified gas 14 was 1879 kcal/h. Furthermore, a quantity of product gas at an outlet 7 of the reforming furnace 25 was 1279 Nm 3 /h, and a heat value of the product gas was 2239 kcal/h. A produced 21 quantity of coal tar was extremely small. In addition, after 200 hours of operation, the reforming furnace 1 was opened to check the inside thereof. No adhesion was found on an inner surface of a furnace wall 1 a of the reforming furnace 1, and the furnace wall 1 a of the reforming furnace 1 was kept clean. 5 [0044] (Example 2) Example 2 was carried out by using an apparatus under reaction conditions which were substantially similar to the apparatus and the reaction conditions of Example 1. In Example 2, among nozzles 4A, 4B of blowing the reformed coal as shown in Fig. 3, each 10 of two first nozzles 4A was installed to face a tangential direction of a virtual circle 24A which had a diameter of 1/3 of a diameter of a reforming furnace 1. Furthermore, among nozzles 4A, 4B of blowing the reformed coal, each of two other second nozzles 4B was installed to face a tangential direction of a virtual circle 24B which had a diameter of 2/3 of a diameter of the reforming furnace 1. 15 [0045] As was the case with Example 1, gasified coal 9 ground to have the average particle size of 40 pm was supplied into a gasification furnace 2 by pneumatic conveyance with the use of nitrogen gas. A quantity of the gasified coal 9 was 500 k/h (coal ash of 2.7%, volatile components of 45%, and moisture content of 5%). Furthermore, a 20 quantity of steam 13 supplied into the gasification furnace 2 was 50 kg/h, and a supplied quantity of oxygen 12 was 310 Nm 3 /h. Furthermore, two first nozzles 4A and two second nozzles 4B were used to supply the reformed coal 10 at a total quantity of 160 kg/h into the reforming furnace 1 in four directions by pneumatic conveyance with the use of nitrogen gas. Pneumatic conveyance 25 was carried out at a rate of 10 m/sec.

22 [0046] In the gasification furnace 2, the gasified coal 9 was blown in four directions which were tangential directions of a virtual circle that had a diameter of 1/3 of the diameter of the gasification furnace; and thereby, a rotational flow was formed. As was 5 the case with Example 1, the gasified coal 9, steam 13 and oxygen 12 were supplied by using double pipe burners. The gasified coal 9 and a carrier gas flowed inside the double pipe. A mixture of the steam 13 and the oxygen 12 flowed outside the double pipe. [0047] As a result, a quantity of the gasified gas 14 at a throat 3, that is, an outlet of the 10 gasification furnace 2, was 1134 Nm 3 /h, a heat value of the gasified gas 14 was 1879 kcal/h, and a temperature of the reforming furnace 1 was 1 100*C. Furthermore, a quantity of product gas at an outlet 7 of the reforming furnace was 1280 Nm 3 /h, and a heat value of the product gas was 2249 kcal/h. In Example 2, an increase in heat value was found as compared with Example 1. Furthermore, after 200 hours of operation, the 15 reforming furnace I was opened to check the inside thereof. No adhesion was found on an inner surface of a furnace wall la of the reforming furnace 1, and the furnace wall Ia of the reforming furnace I was kept clean. [0048] (Comparative Example 1) 20 Comparative Example 1 was carried out by using an apparatus under reaction conditions which were substantially similar to the apparatus and the reaction conditions of Example 1. In Comparative Example 1, as shown in Fig. 4, nozzles 4 of blowing reformed coal were installed to face four directions, and two of which were facing each other. 25 As was the case with Example 1, gasified coal 9 ground to have the average 23 particle size of 40 rn was supplied into a gasification furnace 2 by pneumatic conveyance. A quantity of the gasified coal 9 was 500 kg/h (coal ash of 2.7%, volatile components of 45%, and moisture content of 5%). Furthermore, a quantity of steam 13 supplied into the gasification furnace 2 was 50 kg/h, and a supplied quantity of oxygen 12 was 310 Nm 3 /h. 5 Furthermore, in a reforming furnace 1, reformed coal 10 was supplied in a total quantity of 160 kg/h in four directions to the central axis 0 of the reforming furnace from the reformed-coal blowing nozzles 4 by pneumatic conveyance. Pneumatic conveyance was carried out at a rate of 10 m/sec. [0049] 10 In the gasification furnace 2, the gasified coal 9 was blown in four directions which were tangential directions of a virtual circle that had a diameter of 1/3 of a diameter of the gasification furnace; and thereby, a rotational flow was formed. As was the case with Examples 1 and 2, the gasified coal 9, steam 13 and oxygen 12 were supplied by using double pipe burners. The gasified coal 9 and a carrier gas flowed inside the double 15 pipe, while a mixture of the steam 13 and the oxygen 12 flowed outside the double pipe. [0050] As a result, a quantity of the gasified gas 14 at a throat 3, that is, an outlet of the gasification furnace 2, was 1134 Nm 3 /h, a heat value of the gasified gas 14 was 1879 kcal/h, and a temperature of the reforming furnace 1 was I 100*C. Furthermore, a 20 quantity of product gas at an outlet 7 of the reforming furnace was 1274 Nm 3 /h, and a heat value of product gas was 2168 kcal/h. In Comparative Example 1, a remarkable decrease in heat value was found as compared with Examples 1 and 2. Furthermore, after 200 hours of operation, the reforming furnace 1 was opened to check the inside thereof. Carbonaceous substances seemingly derived from coal were found to adhere on an inner 25 surface of a furnace wall I a of the reforming furnace 1.

24 [0051] (Comparative Example 2) Comparative Example 2 was carried out by using an apparatus and under reaction conditions which were substantially similar to the apparatus and the reaction conditions of 5 Example 1. In Comparative Example 2, reformed coal 10 was supplied into a reforming furnace 1 by pneumatic conveyance in tangential directions of a virtual circle which had a diameter of 1/2 of a diameter of the reforming furnace in the same direction as a rotational flow of gasified coal 9 inside a gasification furnace 2. [0052] 10 As was the case with Example 1, the gasified coal 9 ground to have the average particle size of 40 tm was supplied into the gasification furnace 2 by pneumatic conveyance. A quantity of the gasified coal 9 was 500 kg/h (coal ash of 2.7%, volatile components of 45% and moisture content of 5%). Furthermore, a quantity of steam 13 supplied into the gasification furnace 2 was 50 kg/h, and a supplied quantity of oxygen 12 15 was 310 Nm 3 /h. Furthermore, in the reforming furnace 1, four nozzles 4 of blowing reformed coal were used to supply the reformed coal 10 in a total quantity of 160 kg/h in four directions by pneumatic conveyance. Pneumatic conveyance was carried out at a rate of 10 m/sec. [0053] 20 In the gasification furnace 2, the gasified coal 9 was blown in four directions which were tangential directions of a virtual circle that had a diameter of 1/3 of a diameter of the gasification furnace; and thereby, a rotational flow was formed. As was the case with Examples 1, 2 and Comparative Example 1, the gasified coal 9, steam 13 and oxygen 12 were supplied by using double pipe burnera. The gasified coal 9 and a carrier gas 25 flowed inside the double pipe. The steam 13 and oxygen 12 flowed outside the double 25 pipe. [0054] As a result, a quantity of the gasified gas 14 at a throat 3, that is, an outlet of the gasification furnace 2, was 1134 Nm 3 /h, a heat value of the gasified gas 14 was 1879 5 kcal/h, and a temperature of the reforming furnace 1 was I 100 C. Furthermore, a quantity of product gas at an outlet 7 of the reforming furnace was 1274 Nm 3 /h, and a heat value of the product gas was 2151 kcal/h. In Comparative Example 2, a remarkable decrease in heat value was found as compared with Examples 1, 2 and Comparative Example 1. Furthermore, after 200 hours of operation, the reforming furnace I was 10 opened to check the inside thereof. Carbonaceous substances seemingly derived from coal were found to adhere on an inner surface of a furnace wall Ia of the reforming furnace 1. Description of Symbols 15 [0055] 1: Reforming furnace la: Furnace wall of reforming furnace (furnace wall) 2: Gasification furnace 3: Throat 20 4, 4A, 4B: Nozzle of blowing reformed coal 5: Gasification burner 6: Slag tap 7: Outlet of reforming furnace 8: Water tank 25 9: Gasified coal 26 10: Reformed coal 11: Oxygen-containing gas 12: Oxygen 13: Steam 5 14: Gasified gas 15: Slag 16: Product 17: Boiler pipe 20: Apparatus for thermally decomposing and gasifying coal 10 21: Entrained flow reactor 22, 22A, 22B: Nozzle axis line 23: Virtual line 24, 24A, 24B: Virtual circle a, P: Supply angle 15 0: Central axis of reforming furnace

Claims

1. A method for thermally decomposing and gasifying coal, the method including: using an entrained flow reactor having two tiers of upper 5 and lower chambers which includes a cylindrical gasification furnace as the lower chamber, a cylindrical reforming furnace as the upper chamber, and a throat which is an enlarged diameter portion connecting the furnaces; supplying at least coal and an oxygen-containing gas into the gasification furnace, partially oxidizing the coal so as to produce a gasified gas, and introducing the gasified 10 gas into the reforming furnace; and supplying at least coal into the reforming furnace, and thermally decomposing the coal which has been supplied into the reforming furnace by using sensible heat of the gasified gas, thereby producing a product gas which contains at least hydrogen gas and carbon monoxide gas, 15 wherein the coal to be supplied into the gasification furnace is supplied by pneumatic conveyance so as to form a rotational flow in a circumferential direction inside the gasification furnace, and the coal to be supplied into the reforming furnace is supplied by pneumatic conveyance in a circumferential direction which is opposite to the rotational flow of the 20 coal to be supplied into the gasification furnace.

2. The method for thermally decomposing and gasifying coal according to Claim 1, wherein two or more sites are provided at which the coal is supplied in the reforming furnace, and 25 all of angles of supplying the coal from the two or more sites with respect to a 28 furnace wall of the reforming furnace are set to be a same angle.

3. The method for thermally decomposing and gasifying coal according to Claim 2, wherein the two or more sites of supplying the coal in the reforming furnace are 5 positioned so as to be equally spaced with each other in a circumferential direction on the furnace wall of the reforming furnace.

4. The method for thermally decomposing and gasifying coal according to Claim 2 or 3, wherein apart from the two or more sites of supplying the coal in the reforming 10 furnace, other two or more sites are further provided at which the coal is supplied into the reforming furnace by pneumatic conveyance in a circumferential direction opposite to the rotational flow of the coal to be supplied into the gasification furnace, and all of angles of supplying the coal from the other two or more sites with respect to the furnace wall of the reforming furnace are set to be a same angle, and the angle is 15 different from the angle of supplying the coal from the two or more sites.

5. The method for thermally decomposing and gasifying coal according to Claim 4, wherein the two or more sites of supplying the coal and the other two or more sites of supplying the coal in the reforming furnace are alternately positioned in a 20 circumferential direction.

6. An apparatus for thermally decomposing and gasifying coal which is used in the method for thermally decomposing and gasifying coal according to any one of Claims I to 5, 25 the apparatus including an entrained flow reactor having two tiers of upper and 29 lower chambers which includes a cylindrical gasification furnace as the lower chamber, and a cylindrical reforming furnace as the upper chamber, wherein the gasification furnace includes nozzles of supplying at least coal into the gasification furnace by pneumatic conveyance, and nozzles of supplying an 5 oxygen-containing gas into the gasification furnace, the nozzles of supplying at least the coal into the gasification furnace by pneumatic conveyance are arranged so that the coal to be supplied into the gasification furnace forms a rotational flow in a circumferential direction inside the gasification furnace, 10 the reforming furnace includes nozzles of supplying coal into the reforming furnace by pneumatic conveyance, and the nozzles of supplying the coal into the reforming furnace by pneumatic conveyance are arranged so that the coal is supplied in a circumferential direction opposite to the rotational flow of the coal to be supplied into the gasification furnace. 15