JP2009270814A - Combustion equipment, and method for operating the combustion equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide combustion equipment suppressing generation of clinker and enabling stable combustion in a fluidized bed combustion chamber. <P>SOLUTION: A boiler equipment 1 comprises a fluidized bed combustion tower 5 using coal containing FeS<SB>2</SB>as its fuel, a magnetic discriminator 13 for discriminating magnetic powder Am containing FeS<SB>1-x</SB>(x=0 to 0.2) from ash Ba discharged from the combustion tower 5, and a powder returning line 17 for returning nonmagnetic ash An from which the FeS<SB>1-x</SB>(x=0 to 0.2) is separated by the magnetic discriminator 13 to the combustion tower 5. As a result, the FeS<SB>1-x</SB>(x=0 to 0.2) which might produce highly-viscous clinker can be actively recovered from the combustion tower 5, and generation of the clinker can be suppressed, which enables the stable combustion in the fluidized bed combustion tower 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a combustion facility having a fluidized bed combustion chamber using sulfide-containing coal as a fuel, and a method for operating the combustion facility.

  Conventionally, combustion equipment such as boiler equipment equipped with a fluidized bed incinerator is known. For example, in Patent Document 1, a granular material containing fuel is introduced into a furnace section that is a combustion chamber to form a fluidized bed, and the fluidized bed is fluidized by passing air through the fluidized bed. A fluidized bed combustor is described that facilitates combustion of fuel at relatively low temperatures by forming a bed.

Various fuels are required to be used as fuel applied to combustion equipment such as boiler equipment, and in particular, it is desired to use low-grade coal instead of conventional coal. Among low-grade coals, there are coals rich in sulfides, for example, iron disulfide (FeS ₂ ). Such low-grade coal is thermally decomposed into FeS _(1-x) in the furnace section, and then sulfur (S) in FeS _(1-x) is further thermally decomposed to form sulfur oxide (SO _x ). It becomes. It is necessary to suppress the release of sulfur oxide (SO _x ) into the atmosphere as much as possible in consideration of the environment. For this purpose, an adsorbent such as limestone is introduced into the furnace section.

JP-A-4-227403

In a conventional combustion facility, sulfide contained in coal is thermally decomposed to sulfur oxide. For example, in the case of iron disulfide (FeS ₂ ), it is converted to FeS _(1-x) by thermal decomposition, and is further thermally decomposed to sulfur oxide (SO _x ). Here, in order to thermally decompose FeS _(1-x) to sulfur oxide (SO _x ), it is necessary to hold it in a furnace (combustion chamber) for a long time while maintaining a high temperature of about 900 ° C. However, FeS _(1-x) has a lower melting point than iron or the like, and if it stays in the combustion chamber for a long time, it may become a viscous clinker and may make fluidized bed fluidization unstable. There was a possibility of destabilizing the combustion.

  The present invention aims to solve the above problems, and provides a combustion facility that suppresses the generation of clinker due to sulfides in coal and enables stable combustion in a fluidized bed combustion chamber. The purpose is to do.

  The present invention relates to a combustion facility having a fluidized bed combustion chamber that uses sulfide-containing coal as a fuel, and magnetic separation means that separates magnetic materials by magnetic separation from the ash discharged from the combustion chamber, and magnetic separation means. And a return line for returning the non-magnetic material from which the magnetic material has been separated to the combustion chamber.

In the present invention, among the ash produced in the combustion chamber, the metal sulfide is separated by magnetic separation by the magnetic separation means, and only the non-magnetic material is returned to the combustion chamber. Since the non-magnetic material is reused as a fluidized material that forms a fluidized bed, it is possible to suppress the additional input amount of fluidized material for maintaining the fluidized bed. As a result, while preventing the fluidized bed from becoming unstable due to the reduction of the fluidized material, without waiting for the metal sulfides such as FeS _(1-x) to be thermally decomposed to sulfur oxide (SO _X ), The metal can be actively discharged from the combustion chamber as ash. As a result, it is possible to positively collect metal sulfides that may generate a highly viscous clinker from the combustion chamber, suppress the generation of clinker, and enable stable combustion in a fluidized bed combustion chamber.

Further, it is preferable to further include a roasting furnace that receives the magnetic material separated by the magnetic separation means, and a metal recovery unit that recovers the metal generated by heating the magnetic material in the roasting furnace. In the metal sulfide, sulfur (S) is thermally decomposed in a roasting furnace to produce sulfur oxide (SO _x ) and a metal, and the metal can be recovered by the metal recovery unit. In particular, coal as low-grade coal may contain indium, which is a rare metal in addition to iron, etc., and these metals can be efficiently recovered from the coal, enabling effective use of resources. Become.

It is preferable to further include an exhaust gas return line for returning the combustion exhaust gas discharged from the roasting furnace to the combustion chamber. By returning the combustion exhaust gas containing sulfur oxide (SO _X ) generated in the roasting furnace to the combustion chamber, the sulfur oxide can be treated efficiently.

  Furthermore, it is preferable to use a plasma torch as a heat source for the roasting furnace. When a plasma torch is used as a heat source for a roasting furnace, the oxygen concentration in the roasting furnace can be kept lower than that of a normal fuel combustion burner. As a result, the oxidation of the metal generated in the roasting furnace can be suppressed. Furthermore, the amount of exhaust gas can be reduced by using a plasma torch.

  Furthermore, it is preferable that a power generation means for generating power using heat obtained in the combustion chamber is further provided, and at least a part of the power generated by the power generation means is supplied to the plasma torch. Since at least part of the power generated by the power generation means can be used, it is not necessary to receive power from another power generation facility.

  Further, the present invention relates to a method for operating a combustion facility having a fluidized bed type combustion chamber using sulfide-containing coal as fuel, extracting ash discharged from the combustion chamber, and magnetic material from the ash is magnetically extracted. It is characterized by being separated and removed by sorting and returning the remaining non-magnetic material to the combustion chamber. According to the present invention, it is possible to positively recover only metal sulfides that are likely to generate in-furnace clinker, and to suppress the generation of in-furnace clinker and improve combustion efficiency. ADVANTAGE OF THE INVENTION According to this invention, the metal sulfide which has a possibility of producing | generating a highly viscous clinker can be actively collect | recovered from a combustion chamber, generation | occurrence | production of a clinker can be suppressed, and the stable combustion in a fluidized bed type combustion chamber is enabled.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the clinker resulting from the sulfide in coal is suppressed, and the stable combustion in a fluid bed type combustion chamber is enabled.

It is a figure showing roughly boiler equipment concerning a 1st embodiment of the present invention. It is sectional drawing which shows schematically the magnetic selector which concerns on this embodiment. It is sectional drawing which shows schematically the kiln rotary furnace which concerns on this embodiment. It is a graph showing the relationship between the temperature and the FeS and concentration of FeS ₂ in the combustion tower. It is a graph showing the relationship between the temperature and SO ₂ and O ₂ concentration in the combustion time elapsed and the combustion tower. It is a phase state diagram of Fe and FeS. It is a figure showing roughly boiler equipment concerning a 2nd embodiment of the present invention.

Hereinafter, a preferred embodiment of a combustion facility according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating a combustion facility according to the first embodiment, FIG. 2 is a diagram schematically illustrating a magnetic separator, and FIG. 3 is a diagram schematically illustrating a kiln rotary furnace.
(First embodiment)

  As shown in FIG. 1, a boiler facility 1 (combustion facility) is installed in a power generation facility or the like, and includes a combustion device 3 that uses coal, particularly low-grade coal containing a large amount of sulfide as fuel. The combustion apparatus 3 includes a combustion tower 5 that is a fluidized bed combustion chamber, a cyclone separator 7 that separates solids from the flue gas generated in the combustion tower 5, and a heat exchange unit that recovers heat from the flue gas. 9 and a bag filter 11 for removing dust in the exhaust gas discharged from the heat exchange unit 9. This type of boiler equipment 1 is also called a CFB boiler.

  In the combustion tower 5, coal C1 as fuel and limestone as an adsorbing material for removing sulfur (S) are charged. Air is supplied to the combustion tower 5 from below, and the solid matter containing coal C1 and limestone is fluidized to form a fluidized bed Fb made of a combustible material. By the formation of the fluidized bed Fb, the combustion of the coal C1 is promoted. The combustion gas generated as a result of the combustion rises in the combustion tower 5 with a part of the solid matter.

  The cyclone separator 7 is disposed adjacent to the combustion tower 5 and receives the flue gas discharged from the combustion tower 5 and the particulate solid accompanying the flue gas, and is separated from the flue gas by a centrifugal separation action. The particulate solid is separated, the particulate solid is returned to the combustion tower 5, and the flue gas is sent to the heat exchange unit 9.

  In the heat exchange part 9, the heat from the flue gas is recovered by steam or the like. Part of the sulfur in the dust accompanying the flue gas burns in the heat exchange unit 9. Moreover, the bag filter 11 captures soot and dust in the exhaust gas discharged from the heat exchange unit 9, and the exhaust gas that has passed through the bag filter 11 is sent to another processing facility or released to the atmosphere.

  In addition, the boiler equipment 1 includes a magnetic separator 13 (magnetic separator) that receives the ash Ba discharged from the combustion tower 5 and a vibration sieve 15 that selects nonmagnetic substances magnetically selected by the magnetic separator 13 by a sieving action. A powder return line 17 (return line) for returning the fine ash having a particle size selected by the vibration sieve 15 to the combustion tower 5, and a kiln rotary furnace for again burning the magnetic material selected by the magnetic separator 13 19, a residue recovery unit 21 that recovers the residue Rf discharged from the kiln rotary furnace 19, and an exhaust gas return line 23 that returns the combustion exhaust gas from the kiln rotary furnace 19 to the combustion tower 5 and the heat exchange unit 9. ing.

Coal (low-grade coal) C1 charged into the combustion tower 5 contains a large amount of sulfides such as iron disulfide (FeS ₂ ), and in the combustion tower 5 simultaneously with combustion of combustibles, FeS ₂ and FeS _{(1-x) and the} like are thermally decomposed into sulfur oxide (SO _x ). Here, the substance produced by the combustion in the combustion tower 5 and the influence on the fluidized bed Fb will be described with reference to FIGS. FIG. 4 is a graph showing the relationship between the temperature in the combustion tower 5 and changes in the concentrations of FeS ₂ and FeS. FIG. 5 is a graph showing the relationship between the elapsed combustion time, the temperature in the combustion tower 5 (furnace temperature), and the change in the concentration of SO ₂ and O ₂ at the upper end outlet (furnace outlet) of the combustion tower 5. FIG. 6 is a phase diagram of Fe and FeS.

As shown in FIG. 4, iron disulfide coal C1 (low rank coal) containing a large amount of (FeS _2), when heated to above about 500 ° C iron disulfide (FeS ₂₎ is thermally decomposed Thus, FeS _1-x (x = 0 to 0.2) is generated. As shown in FIG. 5, for example, the sulfur oxide (SOx) generated at this stage rapidly increases the SO ₂ concentration in the combustion tower 5 to a peak, and then rapidly decreases.

In order to thermally decompose FeS _1-x (x = 0 to 0.2) until it becomes sulfur oxide (SOx), it is necessary to keep the state heated to about 900 ° C. for a long time. As shown in FIG. 6, FeS _1-x (x = 0 to 0.2) has a low melting point, and FeS _1-x (x = 0 to 0.2) stays in the combustion tower 5 over a long period of time. Then, a clinker is produced | generated by FeS1 _-x (x = 0-0.2) and another ash content. The clinker has a high viscosity, and if it adheres to the solids forming the fluidized bed Fb, it becomes a factor that hinders fluidization, and there is a possibility that the combustion in the combustion tower 5 becomes unstable. Therefore, in the boiler equipment 1 according to the present embodiment, the ash (bottom ash) Ba in the combustion tower 5 is extracted early and sent to the magnetic separator 13 in order to suppress the generation of clinker.

  A discharge part 5a for discharging ash Ba is provided at the bottom of the combustion tower 5, and a powder transfer line 25 communicating with the magnetic separator 13 is connected to the discharge part 5a. In the powder transfer line 25, powder transfer means such as a screw conveyor is arranged.

Ash Ba containing FeS _1-x (x = 0 to 0.2) is fed into the magnetic separator 13. FeS _1-x (x = 0 to 0.2) is magnetized, and a magnetic substance containing FeS _1-x (x = 0 to 0.2) and a non-magnetic substance mainly composed of ash are magnetic. Magnetic sorting is performed by the sorter 13.

As shown in FIG. 2, the magnetic force sorter _{13, FeS 1-x (x =} 0~0.2) receiving ash Ba _{containing, FeS 1-x (x =} 0~0.2 by and vibrating screen ) 13a is peeled off from other ash. Further, the magnetic separator 13 is magnetically coupled with a pair of left and right magnetic drums 13b that adsorb FeS _1-x (x = 0 to 0.2) flowing down from the hopper 13a and a peripheral surface of the magnetic drum 13b. A pair of left and right scrapers 13c for collecting particulate FeS _1-x (x = 0 to 0.2) adsorbed on the peripheral surface of the drum 13b. Note that FeS _1-x (x = 0 to 0.2) is concentrated in powder (hereinafter referred to as “magnetic powder”) Am as a magnetic material scraped off by the scraper 13c, and this magnetic powder Am Is transferred to the kiln rotary furnace 19 by a transfer device such as a conveyor.

  Ash content (hereinafter referred to as “non-magnetic ash”) An that flows from between the magnetic drums 13 b as non-magnetic material is put into the vibration sieve 15. In the vibration sieve 15, the nonmagnetic ash An is sorted by the particle size, and the nonmagnetic ash An having a large particle size on the sieve is transferred to another processing facility or disposed of as a non-magnetic ash having a small particle size. An is returned to the combustion tower 5 by the powder return line 17. Transfer means such as a screw conveyor is arranged in the powder return line 17.

The nonmagnetic ash An returned to the combustion tower 5 becomes a fluidized material (also referred to as “bed material”) that forms the fluidized bed Fb. By returning the non-magnetic ash An, it is possible to suppress a new additional input amount of the fluid material. In particular, since the non-magnetic ash An has FeS _1-x (x = 0 to 0.2) removed. It is effective in suppressing the generation of clinker.

  As shown in FIG. 3, the kiln rotary furnace 19 includes a vertical kiln, but a horizontal kiln is employed in this embodiment. The kiln rotary furnace 19 includes a cylindrical roasting furnace 27 for roasting magnetic powder Am, and a secondary combustion chamber 29 for secondary combustion of combustion exhaust gas discharged from the roasting furnace 27.

  A gear 27a is provided on the outer periphery of the roasting furnace 27, and the roasting furnace 27 is rotated around the axis L by a motor (not shown). The roasting furnace 27 is inclined downward from the receiving side Us toward the discharging side Ds so that the magnetic powder Am can be moved from the receiving side Us to the discharging side Ds. The roasting furnace 27 and the secondary combustion chamber 29 are joined so that the roasting furnace 27 can rotate and the airtightness of the joint is maintained. The residue Rf and the combustion exhaust gas after oxidizing and roasting the magnetic powder Am are introduced into the secondary combustion chamber 29 from the discharge port of the roasting furnace 27, the residue Rf falls, and the combustion exhaust gas rises. The combustion exhaust gas is subjected to secondary combustion in the secondary combustion chamber 29 and then returned to the combustion tower 5 and the heat exchange unit 9 (see FIG. 1) via an exhaust gas return line 23 having a return pipe.

  A receiving wall 27 c connected to the fixed quantity supply device 33 is formed in the front wall 27 b which is an end surface on the receiving side Us of the roasting furnace 27. In addition, a burner 31 as a heating means is disposed through the front wall 27b. The burner 31 emits a flame from the front wall 27 b toward the discharge side Ds of the roasting furnace 27. Fuel such as heavy oil is supplied to the burner 31 from a fuel tank by a fuel pump (not shown). Combustion air is supplied to the burner 31 through a blower (not shown).

  The fixed amount supply device 33 includes a cylinder part 33a connected to the receiving port 27c of the front wall 27b, a pushing part 33b that reciprocates within the cylinder part 33a, a feeder 33c that drives and controls the reciprocating movement of the pushing part 33b, A hopper 33d communicating with the cylinder portion 33a is provided. The magnetic powder Am from the magnetic separator 13 is put into the hopper 33d. A fixed amount of the magnetic powder Am deposited in the hopper 33d is supplied into the roasting furnace 27 by the reciprocating motion of the pushing portion 33b. The fixed amount supply device 33 may be a device that supplies the magnetic powder Am into the roasting furnace 27 by a screw conveyor or the like.

  The magnetic powder Am supplied into the roasting furnace 27 is heated by the burner 31 from the beginning of supply. In the roasting furnace 27, the magnetic powder Am is heated to about 900 ° C. while being stirred, and moves from the receiving side Us to the discharging side Ds. An air supply line (not shown) is connected to the receiving side Us of the roasting furnace 27, and the direction in which the magnetic powder Am moves in the roasting furnace 27 and the air introduced into the roasting furnace 27 are in parallel. . The kiln rotary furnace 19 having such a gas flow is called a parallel flow type. In addition, although this embodiment is a parallel flow type, the counterflow type kiln rotary furnace 19 with which the moving direction of magnetic powder Am and the air introduced into the roasting furnace 27 oppose may be sufficient.

In FeS _1-x (x = 0 to 0.2) contained in the magnetic powder Am in the roasting furnace 27, sulfur (S) is thermally decomposed to become sulfur oxide (SO _X ), and in the residue Rf Remains iron as Fe or FeO. The combustion exhaust gas containing sulfur oxide (SO _X ) and the residue Rf are discharged from the roasting furnace 27 to the secondary combustion chamber 29. The secondary combustion chamber 29 is provided with a bifurcated first discharge port 29a and a second discharge port 29b for separating the residue Rf and the flying dust. The first discharge port 29 a serving as the outlet for the residue Rf is provided on the roasting furnace 27 side, and the second discharge port 29 b serving as the outlet for the flying dust is provided on the inclined side surface side of the secondary combustion chamber 29. . The residue Rf reaches the first discharge port 29a and is discharged from the first discharge port 29a. On the other hand, the flying dust drops at a lower flow velocity in the secondary combustion chamber 29 and is discharged from the second discharge port 29b. The flying dust contains a large amount of unburned matter, and by providing the bifurcated first and second discharge ports 29b, only the flying dust can be recovered, and the flying dust is again recovered from the roasting furnace 27 and the combustion tower. 5 can also be used.

  A screw conveyor (powder transfer unit) 35 connected to the residue collection unit 21 is connected to the first discharge port 29a. The inlet of the screw conveyor 35 is connected to the first discharge port 29 a, and the outlet is connected to the residue recovery unit 21. The residue Rf containing the iron raw material (Fe or FeO) is recovered by the residue recovery unit 21. The residue Rf is mainly composed of iron, and can be effectively used by an electric furnace refining maker as a high-purity iron material. Further, the residue Rf may contain a trace amount of rare metal (for example, indium), and such a rare metal can be efficiently recovered. The residue collection unit 21 corresponds to the metal collection unit of the present invention.

Next, the operation method of the boiler equipment 1 will be described. Coal C1 and limestone, which are low-grade coal, are charged into the combustion tower 5 of the boiler facility 1 and heated to about 900 ° C. to burn the coal C1. Iron sulfide (FeS ₂ ) in the coal C ₁ is decomposed into FeS _1-x (x = 0 to 0.2) in the combustion tower 5, and as a result, the SO ₂ concentration in the combustion tower 5 rapidly increases. When the peak is reached, it decreases rapidly (see FIG. 5). In order to suppress the generation of clinker by FeS _1-x (x = 0 to 0.2), the ash Ba (bottom ash) in the combustion tower 5 is extracted after a predetermined time has elapsed. This predetermined time is, for example, the time until the SO ₂ concentration decreases beyond the peak and is assumed to rise again thereafter, or the content of FeS _1-x in the extracted ash Ba is analyzed and investigated. The time estimated from the concentration, for example, about 30 to 80 minutes, or can be appropriately determined.

Next, the ash Ba extracted from the combustion tower 5 is put into the magnetic separator 13, and the magnetic separator 13 contains the magnetic powder Am containing FeS1 _-x (x = 0 to 0.2) and the non-ash containing ash. Separated into magnetic ash An. Furthermore, the particle size of the nonmagnetic ash An is adjusted by the vibration sieve 15 and only the fine particles are returned to the combustion tower 5.

On the other hand, the magnetic powder Am enriched with FeS _1-x (x = 0 to 0.2) is charged into the roasting furnace 27 of the kiln rotary furnace 19. In the roasting furnace 27, the magnetic powder Am is heated to about 900 ° C., and FeS _1-x (x = 0 to 0.2) is thermally decomposed into sulfur oxide (SO _X ) and iron. Here, iron remains in the residue Rf as Fe or iron oxide (FeO). The combustion exhaust gas containing SO _X is returned to the combustion tower 5 and the heat exchange unit 9, and the residue Rf containing the iron raw material (Fe or FeO) is recovered by the residue recovery unit 21. By recovering the solid residue Rf mainly composed of Fe discharged from the roasting furnace 27, it can be effectively used by an electric furnace refining maker as a high-purity iron material.

In the operation method of the boiler equipment 1 and the boiler equipment 1 described above, the ash containing metal sulfide such as FeS _1-x (x = 0 to 0.2) generated by the combustion apparatus 3 including the fluidized bed type combustion tower 5 is used. Among the Ba, magnetic powder Am enriched with FeS _1-x (x = 0 to 0.2) is magnetically selected, and only the nonmagnetic ash An is returned to the combustion tower 5. Since the non-magnetic ash An is reused as the fluidized material that forms the fluidized bed Fb, the additional input amount of fluidized material for maintaining the fluidized bed Fb can be suppressed. As a result, metal sulfide such as FeS _(1-x) generated in the combustion tower 5 is thermally decomposed into sulfur oxide (SO _X ) while suppressing instability of the fluidized bed Fb due to reduction of the fluidized material. It can be actively discharged from the combustion tower 5 as ash Ba without waiting. As a result, it is possible to positively recover metal sulfides that are likely to generate a highly viscous clinker from the combustion tower 5, suppress the generation of clinker, and enable stable combustion in the fluidized bed type combustion tower 5.

Further, in the present embodiment, the metal sulfide Am such as FeS _(1-x) (x = 0 to 0.2) in the magnetic powder Am is oxidized by sulfur decomposition of sulfur (S) in the roasting furnace 27. object (SO _X), and the is residue Rf which include metal such as iron is produced, it is possible to recover the residue Rf in the residue recovery unit 21. In particular, the coal C1 as low-grade coal is likely to contain a rare metal such as indium in addition to iron. Therefore, according to this embodiment, further effective utilization of resources becomes possible by efficiently recovering these metals from the coal C1.

In addition, the sulfur oxide (SO _X ) -containing combustion exhaust gas generated in the roasting furnace 27 is returned to the combustion tower 5 and the heat exchange unit 9, so that the sulfur oxide (SO _X ) can be treated efficiently.
(Second Embodiment)

  Next, with reference to FIG. 7, the boiler equipment which concerns on 2nd Embodiment is demonstrated. FIG. 7 is a diagram schematically showing the boiler facility according to the second embodiment. In addition, about the boiler equipment which concerns on 2nd Embodiment, it demonstrates centering around difference with the boiler equipment which concerns on 1st Embodiment, and attaches | subjects the same code | symbol about the element and member similar to 1st Embodiment. Detailed description will be omitted.

  As shown in FIG. 1, a boiler facility (combustion facility) 1B includes a combustion device 3 that uses coal, particularly low-grade coal containing a large amount of sulfide as fuel. The combustion apparatus 3 includes a combustion tower 5 that is a fluidized bed combustion chamber, a cyclone separator 7 that separates solids from flue gas generated in the combustion tower 5, and saturated steam generated in the combustion tower 5 A steam superheater (steam superheating means) 51 that further heats by the heat from the flue gas to generate superheated steam, and a bag filter 11 that removes dust in the flue gas discharged from the steam superheater 51. I have. This type of boiler equipment 1B is also called a CFB boiler.

  Moreover, the boiler equipment 1B includes a turbine that rotates by receiving superheated steam generated by the steam superheater 51, and includes a power generation device (power generation means) 53 that generates power by the rotation of the turbine.

  The magnetic powder Am subjected to magnetic separation by the magnetic separator 13 is transferred to the kiln rotary furnace 19 by a transfer device such as a conveyor. In the kiln rotary furnace 19 according to the present embodiment, a plasma torch 55 is used instead of the burner 31 as a heat source of the roasting furnace 27, and the magnetic powder Am supplied into the roasting furnace 27 is a plasma torch. 55 is heated to about 900 ° C. while being stirred in the roasting furnace 27.

  The plasma torch 55 is, for example, a non-migrating DC plasma torch 55, and a hollow cylindrical anode part and a cathode part are arranged inside a cylindrical casing (shroud). An arc is generated between the two parts. A plasma gas such as air, argon or nitrogen is supplied between the anode part and the cathode part, and a plasma jet is generated to heat the inside of the roasting furnace 27. A gas supply device 57 that supplies plasma gas to the plasma torch 55 and a power generation device 53 that applies a predetermined potential to the plasma torch 23 are connected to the plasma torch 55.

Metal sulfides such as FeS _(1-x) (x = 0 to 0.2) in the magnetic powder Am are heated in the roasting furnace 27, so that sulfur (S) is thermally decomposed and sulfur oxides. (SO _X ) and a residue Rf containing a metal such as iron is generated, and the residue Rf can be recovered by the residue recovery unit 21. In particular, the coal C1 as low-grade coal is likely to contain a rare metal such as indium in addition to iron. Therefore, according to this embodiment, further effective utilization of resources becomes possible by efficiently recovering these metals from the coal C1.

  In particular, in the present embodiment, by using the plasma torch 55 as a heat source, the oxygen concentration in the roasting furnace 27 can be suppressed to be lower than that of the fuel combustion burner. By reducing the oxygen concentration in the roasting furnace 27, it is possible to prevent the metal, for example, iron in the residue Rf from being reoxidized as shown in the following formula (1). Further, the amount of exhaust gas can be reduced by using the plasma torch 55, and as a result, the processing burden for releasing the exhaust gas to the atmosphere is reduced.

2Fe + O ₂ = 2FeO (1)

  The power generation device 53 is connected to the plasma torch 55 so as to be able to supply power, and supplies at least a part of the generated power to the plasma torch 55. As a result, the boiler equipment 1B is economical because it is not necessary to receive power from another power generation facility in order to drive the plasma torch 55.

As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. For example, in the above embodiment, iron disulfide is exemplified as the sulfide, and FeS _1-x (x = 0 to 0.2) is exemplified as the metal sulfide. However, metals other than iron, such as cobalt, gallium, indium, It may be a compound of molybdenum, nickel, silver or tin and sulfur.

  In the second embodiment, the mode in which the plasma torch is attached to the furnace main body of the kiln rotary furnace has been described. However, a chamber different from the furnace main body is provided, and the plasma torch is attached to the chamber. The aspect which heats the inside of a roasting furnace by supplying the hot gas heated inside in the roasting furnace of a kiln rotary furnace may be sufficient. This aspect also uses a plasma torch as a heat source for the roasting furnace.

  DESCRIPTION OF SYMBOLS 1,1B ... Boiler equipment (combustion equipment), 5 ... Combustion tower (combustion chamber), 17 ... Powder return line (return line), 19 ... Magnetic separator (magnetic separation means), 21 ... Residue collection part (metal collection part) ), 23 ... exhaust gas return line, 27 ... roasting furnace, 55 ... plasma torch, 53 ... power generation device (power generation means), Am ... magnetic powder (magnetic material), An ... non-magnetic ash (non-magnetic material), Ba ... Ash, C1 ... coal, Rf ... fluidized bed.

Claims (6)

In a combustion facility equipped with a fluidized bed type combustion chamber using sulfide-containing coal as fuel,
Of the ash discharged from the combustion chamber, magnetic separation means for separating magnetic materials by magnetic separation,
A combustion facility, comprising: a return line for returning the non-magnetic material separated from the magnetic material by the magnetic separation means to the combustion chamber. A roasting furnace for receiving the magnetic material separated by the magnetic separation means;
The combustion facility according to claim 1, further comprising: a metal recovery unit that recovers a metal generated by heating the magnetic substance in the roasting furnace.   The combustion equipment according to claim 2, further comprising an exhaust gas return line for returning the combustion exhaust gas discharged from the roasting furnace to the combustion chamber.   The combustion facility according to claim 2 or 3, wherein a plasma torch is used as a heat source of the roasting furnace.   5. The power generation unit according to claim 4, further comprising a power generation unit configured to generate power using heat obtained in the combustion chamber, wherein at least a part of the power generated by the power generation unit is supplied to the plasma torch. Combustion equipment. In a method for operating a combustion facility equipped with a fluidized bed combustion chamber that uses sulfide-containing coal as fuel,
A method for operating a combustion facility, wherein the ash discharged from the combustion chamber is extracted, magnetic materials are separated and removed from the ash by magnetic separation, and the remaining non-magnetic materials are returned to the combustion chamber.

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