JP6098804B2 - Mixed gas blowing device, waste gasification and melting furnace having the same, mixed gas blowing method, and waste gasification and melting method using the same - Google Patents

Description

  The present invention relates to a mixed gas blowing apparatus, a waste gasification melting furnace having the same, a mixed gas blowing method, and a mixed gas blowing method for a waste gasification and melting furnace for thermally decomposing and burning waste and melting a pyrolysis residue. The present invention relates to a waste gasification and melting method using the above.

  As a technology for treating waste such as municipal waste and shredder dust, waste melting treatment is known in which waste is pyrolyzed and burned to melt the pyrolysis residue into slag and discharge it.

  This treatment method can recover the heat of combustion by pyrolyzing and gasifying waste, and it should be disposed of in landfills after melting the pyrolysis residue and discharging it as slag. It has the advantage that the volume can be reduced. There are several methods for such melting treatment, and one of them is a method using a shaft furnace type waste gasification melting furnace having a vertical shape.

  This shaft furnace type waste gasification melting furnace, for example, burns coke deposited in the lower part of the furnace, throws the waste on this high temperature coke, pyrolyzes and partially oxidizes it, and gasifies it as residue Is a furnace that performs a process of melting slag into slag (see Patent Document 1).

  In the shaft furnace type waste gasification and melting furnace of Patent Document 1, the functions of a vertical cylindrical furnace body are roughly divided into three regions in the vertical (up and down) direction. That is, a high-temperature combustion zone having a coke bed with coke deposited at the lower part of the furnace is formed, a waste layer is formed on the high-temperature combustion zone, and a large space above the waste layer at the upper part of the furnace body. The free board part is made.

  In such a gasification melting furnace, oxygen-containing gas is blown into the furnace in each of the three regions. A main tuyere is provided in the high-temperature combustion zone at the bottom of the furnace, and oxygen is enriched to obtain a melting heat source that burns the coke of the coke bed deposited and deposited to melt the pyrolysis residue of waste Air is blown. In addition, the waste layer is provided with a sub tuyere, and air is blown in order to gently flow the waste deposited and deposited, and to thermally decompose and partially oxidize the waste. In addition, the free board part is provided with a third stage tuyere to partially burn part of the pyrolysis gas (combustible gas) generated by pyrolyzing waste and maintaining the inside at a predetermined temperature Air is blown.

  As described above, the shaft furnace type waste gasification and melting furnace is a facility capable of performing both pyrolysis gasification treatment and melting treatment in one furnace as the waste falls in the furnace. The input waste is pyrolyzed to produce gas and residue. The coke in the coke floor is combusted by blowing oxygen-enriched air from the main tuyere to form a high-temperature combustion zone, and the pyrolysis residue of the waste is melted and discharged as slag and metal. The coke floor is a gap created between cokes, and it functions as a high-temperature grate that allows oxygen-enriched air from the main tuyere and high-temperature gas generated by coke combustion to flow, and also allows molten slag and metal to flow. ing. The high-temperature gas generated by coke combustion in the high-temperature combustion zone heats the waste in the waste layer formed on the high-temperature combustion zone, and the waste is thermally decomposed by blowing air from the sub tuyere. The gas containing the combustible gas generated by the gas rises in the waste layer, and is discharged to the secondary combustion chamber outside the furnace from the exhaust flue provided in the upper part of the furnace through the free board part. The gas contains a large amount of combustible gas and is combusted in the secondary combustion chamber, and heat is recovered by the boiler to generate steam, which is used for power generation and the like. Exhaust gas treatment, such as removing relatively coarse dust with a cyclone, cooling with a temperature reducing device, removing harmful gas by reaction with a hazardous substance remover, and removing dust with a dust collector And then released from the chimney to the atmosphere.

  In such a waste gasification melting furnace, a coke bed in which coke is deposited at the bottom of the furnace is formed, and the coke burns to become a heat source for melting pyrolysis residues. There is a demand for reducing carbon dioxide emissions by reducing the amount used.

  Therefore, it has been studied to use fuel gas such as LNG, LPG, and combustible gas generated by thermal decomposition in a waste gasification and melting furnace as an alternative to coal coke. It has been proposed to blow fuel gas together with oxygen-enriched air from the mouth (fan tuyere).

  In Patent Document 2, the tip (opening) of the main tuyere (blower tuyere) that feeds oxygen-enriched air into the furnace enters the furnace and enters the coke floor to be positioned. A main tuyere is provided. The fuel gas is supplied into the main tuyere at the tip position of the tuyere and blown out from the tip of the main tuyere with oxygen-enriched air. Therefore, the fuel gas blown out from the tip of the main tuyere and the oxygen-enriched air are not mixed in the main tuyere but mixed between the coke grains in the coke bed after being blown into the coke bed. .

JP 09-060830 A JP 2001-090923 A

  In order to reduce carbon dioxide emissions, even if fuel gas is blown in as a substitute for a part of coke as in Patent Document 2 in order to reduce the amount of coke used in a waste gasification and melting furnace, the following problems occur: There is. That is, in Patent Document 2, the tip of the main tuyere where the fuel gas and oxygen-enriched air are blown out is located in the coke floor and faces the coke deposit layer. The gas cannot be mixed with oxygen-enriched air and burned efficiently. In other words, the space for mixing oxygen-enriched air and fuel gas from the main tuyere into the melting furnace is blocked by unmelted slag or low-temperature coke in the coke bed and is not formed. Therefore, there is a problem that stable combustion may not be performed in a sufficiently mixed state in the coke bed.

  In addition, in order to melt the dust discharged and recovered from the waste gasification melting furnace and to blow it into the coke floor from the main tuyere, Patent Document 2 discloses oxygen enrichment. An appropriate mechanism for blowing air, dust and fuel gas is not disclosed, and there is a problem also in this respect.

  In view of such circumstances, the present invention provides a mixed gas blowing apparatus and method for thoroughly mixing fuel gas with oxygen and air and blowing the mixed gas into the tuyere, and a waste gasification and melting apparatus and method using the mixed gas blowing apparatus and method. Is an issue.

  According to the present invention, the above-described problems can be solved by configuring the apparatus and method as follows. As a device for injecting a mixed gas into a waste melting furnace for combustion, a mixed gas blowing device and a waste gasification melting furnace having the mixed gas, and further as a method, a mixed gas blowing method and a waste gasification melting using the same The method is configured as follows.

<Mixed gas blowing device>
The mixed gas blowing apparatus according to the present invention is a waste gasification melting furnace that thermally decomposes waste in a furnace having a coke bed and melts the residue, into the coke bed of oxygen, air, fuel gas, and waste A mixed gas obtained by mixing dust collected and discharged from the gasification melting furnace is blown from a tuyere provided in the furnace body of the waste gasification melting furnace.

  In the mixed gas blowing apparatus, in the present invention, the mixed gas blowing device includes an air supply pipe that is connected to the tuyere and sends the mixed gas into the furnace body, and the air supply pipe is located upstream of the outer pipe and the tip opening of the outer pipe. A double tube structure having an inner tube in which a tip opening is located, air is supplied to the inner tube and oxygen is supplied to the outer tube, and the inner tube has two different positions in the axial direction. At least one branch port is formed in the outer peripheral surface of the inner pipe, and the branch port located upstream of the two positions supplies dust to the air flowing in the inner pipe. A branch port located on the downstream side is formed as a fuel gas inlet for feeding fuel gas into the air, and the inner pipe is formed in the inner pipe. Air, fuel gas and dust are mixed up to the position of the tip opening After being, and oxygen of the outer tube at the distal end region of the outer tube are mixed thereto characterized in that is adapted to the mixed gas is formed.

  According to such a mixed gas blowing device, dust is supplied into the air feed pipe from the upstream side of two different positions in the axial direction with respect to the air fed in the axial direction toward the tuyere with the inner pipe, and downstream. Fuel gas is supplied from the side position. Therefore, air, dust, and fuel gas are mixed in the inner pipe up to the position of the tip opening of the inner pipe. Further, in the distal end region in the outer tube, oxygen in the outer tube is mixed with this to form a mixed gas. In this way, the gas mixture is formed at the tip region of the outer tube, so there is no obstacle to gas mixing, and the gas mixture is sufficiently mixed until it reaches the tuyere. In this state, it is blown from the tuyere into the coke floor in the furnace. Therefore, the fuel gas burns well in the coke bed.

  In the present invention, the outer pipe of the air supply pipe has branch ports formed at a plurality of positions in the circumferential direction, and these branch ports are formed as oxygen inlets for sending oxygen into the outer pipe. The air supply pipe may have a jacket that forms an annular space that communicates and covers these oxygen inlets.

  In the present invention, when oxygen is supplied through the jacket, the oxygen flows through the annular space in the jacket and is almost uniformly dispersed in the circumferential direction, and then supplied from the plurality of oxygen inlets to the outer tube. Gas formation is promoted. Even if only one supply pipe for supplying oxygen to the jacket is connected to the jacket in the circumferential direction, the fuel gas is dispersed in the jacket in the circumferential direction, so that the number of supply pipes is minimized. It can be a book and the apparatus is simplified.

  Further, in the mixed gas blowing apparatus, in the present invention, the mixed gas blowing device has an air feeding pipe connected to the tuyere and sending the mixed gas into the furnace body, and the gas feeding pipe is upstream of the outer pipe and the distal end opening of the outer pipe. A double pipe structure having an inner pipe with a tip opening located on the side, air is supplied to the inner pipe and fuel gas is supplied to the outer pipe, and the inner pipe is different in the axial direction. At least one branch port is formed in each of the two positions by opening in the outer peripheral surface of the inner tube, and the branch port located on the upstream side of the two positions is used for air flowing in the inner tube. A branch port that is formed as a dust supply port for supplying dust and is located on the downstream side is formed as an oxygen inlet for supplying oxygen to the air, and the inner tube is formed in the inner tube. Air, oxygen and dust are mixed up to the tip opening position of After it may also be characterized in that the fuel gas of the outer tube at the distal end region of the outer tube is mixed thereto so that the above mixed gas is formed.

  According to such a mixed gas blowing device, dust is supplied into the air feed pipe from the upstream side of two different positions in the axial direction with respect to the air fed in the axial direction toward the tuyere with the inner pipe, and downstream. Oxygen is supplied from the side position. Therefore, air, dust, and oxygen are mixed in the inner pipe up to the position of the tip opening of the inner pipe. Further, in the tip region in the outer pipe, the fuel gas in the outer pipe is mixed with the outer pipe to form a mixed gas. In this way, the gas mixture is formed at the tip region of the outer tube, so there is no obstacle to gas mixing, and the gas mixture is sufficiently mixed until it reaches the tuyere. In this state, it is blown from the tuyere into the coke floor in the furnace. Therefore, the fuel gas burns well in the coke bed.

  The air supply pipe is formed by opening a branch port as a fuel gas inlet on the outer peripheral surface of the outer pipe, and the fuel gas from the fuel gas inlet is seen in the axial direction of the air pipe. The feeding direction is deviated from the axis of the outer pipe, and the fuel gas fed from the fuel gas inlet to the tangential direction of the outer pipe generates a swirling flow in the outer pipe. Is preferred.

  In the present invention, when the fuel gas is supplied into the outer pipe so as to generate a swirling flow in the air supply pipe, the fuel gas is rapidly mixed with air, dust and oxygen. Can be made smaller.

  Further, the air supply pipe may have a jacket in which fuel gas inlets are formed at a plurality of positions in the circumferential direction, and an annular space is formed so as to communicate and cover these fuel gas inlets. it can. In the present invention, when the fuel gas is supplied through the jacket, the fuel gas flows through the annular space in the jacket and is substantially uniformly distributed in the circumferential direction, and then supplied from the plurality of fuel gas inlets to the outer pipe. Therefore, the formation of the mixed gas is promoted. Further, even if only one supply pipe for supplying fuel gas to the jacket is connected to the jacket in the circumferential direction, the fuel gas is dispersed in the jacket in the circumferential direction, so that the number of supply pipes is minimized. It can be single, and the apparatus is simplified.

<Waste gasification melting furnace>
The waste gasification and melting furnace is configured by providing the furnace body with the above-described mixed gas blowing apparatus of the present invention.

<Mixed gas injection method>
In the mixed gas blowing method according to the present invention, oxygen, air, fuel gas, and waste are supplied to the coke bed of a waste gasification melting furnace that thermally decomposes waste in a furnace having a coke bed and melts the residue. A mixed gas obtained by mixing dust collected and discharged from the gasification melting furnace is blown from a tuyere provided in the furnace body of the waste gasification melting furnace.

  In this mixed gas blowing method, in the present invention, an air supply pipe connected to the tuyere and sending the mixed gas into the furnace body is connected, and the air supply pipe is upstream of the outer tube and the front end opening of the outer tube. A double tube structure having an inner tube with a tip opening located on the side, supplying air to the inner tube and oxygen to the outer tube, and the inner tube has two different axial directions. At least one branch port is formed in each position at the outer peripheral surface of the inner tube, and the branch port located upstream of the two positions is used as a dust supply port. Dust is supplied to the flowing air from the dust supply port, a branch port located on the downstream side is used as a fuel gas inlet, and fuel gas is supplied to the air from the fuel gas inlet, and the inside of the inner pipe Air, fuel gas and so on up to the position of the opening of the inner pipe After mixing the strike, and characterized by forming the mixed gas is mixed to the oxygen of the outer tube at the distal end region of the outer tube.

  In the present invention, the outer pipe of the air supply pipe has branch ports formed at a plurality of positions in the circumferential direction, and these branch ports are formed as oxygen inlets for sending oxygen into the outer pipe. The air supply pipe has a jacket that forms an annular space that communicates and covers these oxygen inlets, and oxygen is supplied from each oxygen inlet into the outer pipe through the annular space. be able to.

Further, in this mixed gas blowing method, in the present invention, an air supply pipe connected to the tuyere and sending the mixed gas into the furnace body is connected, and the air supply pipe is formed from an outer tube and a front end opening of the outer tube. A double pipe structure having an inner pipe with a tip opening located upstream, supplying air to the inner pipe and fuel gas to the outer pipe, and further, the inner pipe in the axial direction. At least one branch port is formed in each of the two different positions, and the branch port located upstream of the two positions is used as a dust supply port. the dust on the air flowing through the inner tube is supplied from the dust inlet, as inlet feed oxygen branched port located on the downstream side, the oxygen in the air fed from the oxygen inlet port, said at the inner tube Air, oxygen and dust up to the position of the opening of the inner pipe After mixing, by mixing thereto a fuel gas of the outer tube at the distal end region of the outer tube it may also be characterized in that to form the mixed gas.
At that time, the air supply pipe is formed by opening a branch port as a fuel gas inlet on the outer peripheral surface of the outer pipe, and the fuel gas from the fuel gas inlet is seen in the axial direction of the air pipe. The feeding direction is deviated with respect to the axis of the outer pipe, and the fuel gas is fed from the fuel gas inlet to the tangential direction of the outer pipe to generate a swirling flow in the outer pipe. Preferably it is.
The air supply pipe has fuel gas inlets formed at a plurality of positions in the circumferential direction, and has a jacket that forms an annular space that communicates and covers these fuel gas inlets. The fuel gas can be sent into the outer pipe from each fuel gas inlet.

<Waste gasification and melting method>
In the present invention, the waste gasification and melting method is configured to inject a mixed gas into the melting furnace by the above-described mixed gas blowing method, and to the coke bed of the waste gasification and melting furnace by the above-described mixed gas blowing method. It is characterized in that a mixed gas is blown into the furnace body and the waste is pyrolyzed to melt the residue.

  As described above, the present invention comprises a double-pipe structure having an outer tube and an inner tube whose tip opening is located on the upstream side of the tip opening of the outer tube. As the gas mixture forms in the zone, the air, oxygen, fuel gas and dust are in a fully mixed gas state before being blown out of the tuyere into the furnace, resulting in fuel in the coke bed. Gas combustion is performed well. In this way, it is possible to efficiently use the fuel gas as a substitute for a part of coke and use the combustion heat as a melting heat source, so the amount of coke used can be reduced and the amount of carbon dioxide emissions can be reduced.

It is a figure which shows schematic structure of the waste gasification melting apparatus as one Embodiment of this invention. It is an expanded sectional view about the main tuyere in the FIG. 1 apparatus. The main part of the mixed gas blowing apparatus connected to the main tuyere of FIG. 2 is shown, (A) is sectional drawing in the surface containing the axis line of an air supply pipe, (B) is BB sectional drawing in (A), (C) is CC sectional drawing in (A). The principal part of the mixed gas blowing apparatus as other embodiment of this invention is shown, (A) is sectional drawing in the surface containing the axis line of an air supply pipe, (B) is BB sectional drawing in (A), ( (C) is CC sectional drawing in (A).

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the present embodiment, coke and fuel gas are supplied as fuel to the shaft furnace type waste gasification and melting furnace, and the waste is thermally decomposed in the furnace body, and oxygen, air, and fuel gas are supplied to the coke bed where the residue is melted. And a mixed gas blowing device for blowing a mixed gas obtained by mixing dust collected and discharged from the waste gasification and melting furnace from the tuyere. Prior to explanation of these features, FIG. Based on this, the general configuration of this shaft furnace type waste gasification melting furnace will be described.

  A shaft furnace type waste gasification and melting furnace employed in an embodiment of the present invention shown in FIG. 1 includes waste as a processing object and coke as fuel in the upper part of the gasification and melting furnace 1. An inlet 2 for introducing limestone as a slag component adjusting material into the furnace is provided, and a gas outlet 3 for exhausting the gas in the furnace to the outside of the furnace is provided on the upper side. ing. In addition, an outlet 4 for discharging molten slag and molten metal is provided at the bottom of the gasification melting furnace 1.

  In the shaft furnace type waste gasification and melting furnace, the internal space of the gasification and melting furnace 1 is roughly divided into three regions in the vertical direction. This is a region having a middle shaft portion II located at the top and a free board portion III formed at the top. Each of these parts I, II, and III is an area having the following functions. That is, the lower shaft portion I forms a deposited coke bed and burns the coke to form a high-temperature combustion zone, and the middle shaft portion II is formed by the accumulation of wastes put on the high-temperature combustion zone. The region where the waste in the formed waste layer is thermally decomposed, the free board part III, is a region where the generated combustible gas is partially combusted.

  Above the waste gasification and melting furnace 1, a supply device (not shown) for supplying waste such as municipal waste, coke, and limestone used as a component adjusting material for slag to be generated is disposed. Waste, coke, and limestone supplied from this supply device are transported by a transport conveyor (not shown) and charged into the furnace through the charging port 2 at the top of the furnace.

  A tuyere for blowing oxygen-containing gas is provided on the furnace wall for each of the lower shaft portion I, the middle shaft portion II, and the freeboard portion III formed in the waste gasification melting furnace. That is, the lower shaft portion I is provided with a main tuyere 5 that burns the deposited coke to form a high-temperature combustion zone and blows a gas mixture for melting the pyrolysis residue, and the middle shaft portion II In addition, a sub tuyere 6 is provided to blow in air for causing thermal decomposition and combustion while causing the waste deposited and deposited to partially burn and slowly flow the waste. A three-stage tuyere 7 for blowing air for partially burning the combustible gas generated by pyrolysis and maintaining the inside of the furnace at a predetermined temperature is provided.

  A secondary combustion chamber 10 is connected to the gas discharge port 3 and burns combustible gas generated by pyrolyzing waste. An air blowing port 11 for blowing air for secondary combustion is provided. Further, the secondary combustion chamber 10 is provided with a boiler 12 adjacent to which heat is recovered from the combustion gas obtained by burning the combustible gas in the secondary combustion chamber 10.

  Exhaust gas from the boiler 12 is exhausted through an exhaust pipe 13 and is detoxified through a temperature reducing device, a dust collector, and an exhaust gas treatment device (both not shown) provided on the downstream side. To be released.

  The dust contained in the exhaust gas and falling in the secondary combustion chamber 10 and the boiler 12 is dropped and discharged from the secondary combustion chamber 10 and the boiler 12, and together with the dust collected by the dust collector, the dust return path 15 And is attached to the main tuyere 5 via a rotary valve 16A provided at the lower outlet of the dust storage tank 16 after being brought to the dust storage tank 16 provided at a position above the side of the gasification melting furnace 1 It is connected to a dust supply pipe 23 described later provided in the air supply pipe 22 described later, so that the dust is fed back to the furnace. This supply of dust to the main tuyere 5 will be described later again.

  The main tuyere 5 provided in the lower part of the furnace wall 1A of the gasification melting furnace 1 has a conical outer peripheral surface attached to a stepped taper through hole 1B formed in the furnace wall 1A as seen in FIG. It has a base-like holding body 18 having The holding body 18 holds a tip attachment portion 21 attached to the tip of an air supply tube 22 of the mixed gas blowing device 20 described below.

  The tip mounting portion 21 has an outer diameter surface 21A tapered and a cylindrical through hole 21B. A wear-resistant material layer 21C is provided on the inner diameter surface of the through hole 21B. The through hole 21B has a locking portion 21B-1 having a large inner diameter in a step shape on the large outer diameter end side. The holding body 18 that holds the tip mounting portion 21 has a conical bowl shape as described above, and a holding hole 18A is formed at the bottom (right end in the drawing). The holding hole 18A forms a tapered hole that matches the large-diameter end portion of the outer diameter surface of the tip mounting portion 21, and the tapered hole comes into contact with the outer diameter surface of the tip mounting portion 21 to attach the tip mounting portion. The part 21 is held. As described above, the tip mounting portion 21 held by the holding body 18 is held by the holding body 18 attached to the furnace wall 1A of the furnace body, and the tip of the tip mounting portion 21 has a small outer diameter end side tip. Located in the furnace. At least the holding body 18 of the holding body 18 and the tip mounting portion 21 is water-cooled, but since its type is known, the description of the form for water cooling is omitted here.

  As shown in FIG. 3 (A), the mixed gas blowing device 20 having the air feed tube 22 provided with the tip attachment portion 21 at the tip is a double tube in which an inner tube 27 is concentrically arranged in the outer tube 26. The front end opening of the inner tube 27 is located on the left side (upstream side) before the front end opening of the outer tube 26. The outer pipe 26 is provided with an end wall 28 at the upstream end, and the inner pipe 27 extends through the end wall 28 to the upstream side (left side). The inner pipe 27 has two positions that are different from each other in the axial direction serving as the center line of the air supply pipe 22 in the portion extending upstream from the end wall 28, in the illustrated example, a position having a distance from the tip mounting portion 21; A branch port is formed at a position further away from the branch port. The branch port located on the upstream side (left side in the figure) is the dust supply port 23A, and the branch port located on the downstream side is the fuel gas. Used as the inlet 24A. As can be seen in FIG. 3B, which shows a cross section in a plane perpendicular to the axis of the air supply pipe 22 (which is also the axis of the outer pipe 26 and the inner pipe 27), the dust supply port 23A has a circumferential direction. It is formed at the upper surface position of the inner tube 27 at one place. The fuel gas inlet 24A is also formed at the upper surface position of the inner tube 27 at one place in the circumferential direction, like the dust supply port 23A.

  Connected to the dust supply port 23A is a dust supply pipe 23 that forms part of the dust return path 15 and supplies dust to the inner pipe 27. In addition, a fuel gas inlet pipe 24 that supplies fuel gas to the inner pipe 27 is connected to the fuel gas inlet 24A. Air flows downstream in the inner pipe 27 to which the dust supply pipe 23 and the fuel gas inlet pipe 24 are connected.

  As described above, dust is supplied to the inner pipe 27 from the dust supply port 23A, so that the inner wall of the pipe 27 is not damaged by abrasion or the like due to dust flowing toward the downstream side. The inner wall surface of the pipe has a wear-resistant material layer 27A coated with a wear-resistant material in a range downstream of the dust supply port 23A. The wear-resistant material layer 27A extends to the downstream end of the inner tube 27, and the wear-resistant material layer 21C (formed on the inner diameter surface of the conical tip mounting portion 21 attached to the distal end of the inner tube 27 ( In addition, the inner wall is prevented from being damaged by dust. Such wear-resistant material layers 21C and 27A can be formed of, for example, ceramic or wear-resistant clad steel. As the ceramic, for example, at least one of silicon nitride, zirconia, and alumina is used. The wear-resistant material layer can be formed by coating the inner diameter surface of each tube, or can be formed by inserting a sleeve having a thickness of about 10 mm of the wear-resistant material into each tube. In particular, in the case of wear-resistant clad steel, the entire tube may be made of the wear-resistant clad steel. When the wear resistant material sleeve is used, the wear resistant material sleeve can be fixed to the inner diameter surface of the tube by mortar or the like in the outer tube 26.

  The outer pipe 26 is used as an oxygen supply pipe, and a branch port is formed at an upstream position in the axial direction serving as the center line of the air feed pipe 22. The branch port serves as an oxygen inlet 29A. It is used. As can also be seen in FIG. 3C, which shows a cross section in a plane perpendicular to the axis of the air supply tube 22, the oxygen inlet 29A is formed at the upper surface position of the outer tube 26 at one place in the circumferential direction. Yes. An oxygen inlet pipe 29 for supplying oxygen to the outer pipe 26 is connected to the fuel oxygen inlet 29A, and oxygen received from the oxygen inlet pipe 29 flows in the outer pipe 26 toward the downstream side.

  In such an air supply pipe 22, air is sent to the inner pipe 27 toward the downstream end. During the flow, dust is first supplied to the air from the dust supply port 23A, and at the downstream position, the fuel gas is supplied from the fuel gas inlet 24A. Therefore, dust and fuel gas are mixed with the air, and the degree of mixing is increased as the flow progresses until reaching the position of the opening of the inner tube 27. On the other hand, oxygen from an oxygen supply source is pressure-fed into the outer pipe 26 used as an oxygen supply pipe from an oxygen inlet 29A. The air, dust, and fuel gas mixed in the inner pipe 27 are in a range from the front end opening of the inner pipe 27 to the front end opening of the outer pipe 26 in the front end region in the outer pipe 26, that is, in the axial direction of the air supply pipe 22. Is sufficiently mixed with oxygen in the outer tube 26 to form a mixed gas. This mixed gas is blown into the furnace from the tip of the through hole 21B (see FIG. 2) of the tip mounting portion 21.

  The tip attachment portion 21 attached to the tip of the air supply pipe 22 has a tip opening in the furnace and faces the coke bed in the high temperature combustion zone. Even though it can circulate between the grains, it will receive a large ventilation resistance from the coke grains, and it is not in a situation where mixing can be sufficiently performed in the furnace. In this respect, in this embodiment, since the mixed gas is formed in the tip region in the outer tube 26 before being blown into the furnace, there is nothing that hinders gas mixing, and the mixed gas Is blown from the main tuyere 5 into the coke floor in the furnace in a sufficiently mixed state up to the main tuyere 5. Therefore, the fuel gas burns well in the coke bed.

  In the present embodiment configured as described above, the waste gasification and melting treatment is performed as follows.

  Waste, coke, and limestone from the supply device are respectively introduced into the furnace by a predetermined amount through the inlet 2 provided in the upper portion of the gasification melting furnace 1, and main tuyere 5, sub tuyere 6, and three From the stage tuyere 7, air is blown into the furnace. In particular, from the main tuyere 5, as described above, a mixed gas obtained by mixing air, fuel gas, dust, and oxygen in the air supply pipe 22 of the mixed gas blowing device 20 is blown into the furnace. The waste introduced from the inlet 2 is deposited on the middle shaft part II in the furnace to form a waste layer, and from the high temperature gas and sub tuyere rising from the high temperature combustion zone of the lower shaft part I. It is dried by blown air and then partially burned and pyrolyzed. The combustible gas generated by pyrolysis is partly combusted by the air blown from the three-stage tuyere 7 in the free board part III, and the free board part III is kept in a high-temperature reducing atmosphere of 850 ° C. or higher. A process for decomposing toxic gas and tar content is performed, and a gas containing a combustible gas is sent to a secondary combustion chamber 10 provided outside the furnace and subjected to secondary combustion, and heat is recovered from the combustion gas in a boiler 12. .

  The coke descends to the lower shaft portion I to form a high temperature combustion zone (coke bed). The residue resulting from the thermal decomposition of the waste in the waste layer descends and reaches the coke floor of the lower shaft portion I. Pyrolysis residue (ash content, incombustible material) is heated by the combustion of coke and fuel gas in the coke bed and melts into molten slag and molten metal. The molten slag and molten metal are discharged from the tap 4 and supplied to a water granulating device provided outside the furnace, cooled and solidified, and the cooled and solidified granulated slag and granulated metal are recovered. On the other hand, when the dust in the mixed gas blown from the main tuyere reaches the high temperature combustion zone from the main tuyere 5, it is melted and extracted from the outlet 4 at the bottom of the furnace together with the molten pyrolysis residue. In this way, the volume of the landfill is reduced by melting the dust, thereby greatly reducing the amount of landfill disposal.

  In the present embodiment, air, fuel gas, and dust are mixed in the inner tube 27 in a space downstream of the fuel gas inlet 24 </ b> A, and oxygen in the inner tube 26 in the tip region of the outer tube 26. It is blown into the furnace in a mixed state. Therefore, the fuel gas is in a mixed gas state that is sufficiently mixed with oxygen, air, and dust before being blown out from the tuyere into the furnace, and the fuel gas is burned well in the coke bed. In this way, it is possible to efficiently use the fuel gas as a substitute for a part of coke and use the combustion heat as a melting heat source, so the amount of coke used can be reduced and the amount of carbon dioxide emissions can be reduced.

    In the form of FIG. 3, it is preferable that the flow rate of air in the inner pipe 27 is 70 to 120 m / sec, and the flow rate of sending fuel gas from the fuel gas inlet 24A to the inner pipe 27 is 50 to 200 m / sec. By setting the flow velocity in such a range, oxygen, air, and fuel gas can be mixed efficiently, and the mixed gas can reach the preferred range of the coke bed in the furnace from the tuyere, in the coke bed. Fuel gas combustion can be performed satisfactorily.

  In the present invention, the mixed gas blowing device 20 is not limited to the form shown in FIG. 3, and various modifications are possible. For example, in FIG. 3A, one oxygen inlet pipe 29 is attached to the outer pipe 26. For example, oxygen inlets 29A are provided at a plurality of positions in the circumferential direction of the outer pipe 26 to surround them. In this manner, a jacket that forms an annular space may be attached to the outer tube 26, and the oxygen inlet tube 29 may be connected to one place in the circumferential direction of the jacket. This simplifies the pipe system for supplying fuel gas. Oxygen fed from one oxygen feed pipe 29 is dispersed in the jacket, and evenly enters the outer pipe 26 from the plurality of oxygen feed inlets 29A and travels in the circumferential direction. Thus, the pipe system for supplying oxygen is simplified by adopting the form of the mixed gas blowing device having the jacket. Moreover, in the form of the mixed gas blowing apparatus in which the oxygen inlet pipe forms a separate pipe system, the number of oxygen inlets is limited in order to avoid interference between the pipe systems, but the mixed gas blowing apparatus having a jacket Thus, more oxygen inlets can be provided, mixing can be performed more efficiently, and the length of the air supply tube can be shortened and made compact. In addition, it is preferable to provide a jacket in the outer pipe 26 and provide one fuel gas inlet 24A in the outer pipe 26 because the pipe system for supplying fuel gas can be simplified and made compact.

  Further, in the form of FIG. 3, the fuel gas is fed into the inner tube and the oxygen is fed into the outer tube. For example, as shown in FIG. 4, oxygen is fed into the inner tube and fuel gas is fed into the outer tube. Also good. Specifically, as can be seen by comparing FIG. 4A with FIG. 3A, the branch port formed in the inner pipe 27 and forming the fuel gas inlet 24A in FIG. As shown in FIG. 4A, the branch port formed in the outer tube 26 and forming the oxygen inlet 29A is used as the oxygen inlet 24A ′ as shown in FIG. It is used as the entrance 29A ′. Further, as shown in FIG. 4, an oxygen inlet pipe 24 'is connected to the oxygen inlet 24A', and a fuel gas inlet pipe 29A 'is connected to the fuel gas inlet 29A'.

  In the form of FIG. 4, as is often seen in FIG. 4C, the plurality of fuel gas inlets 29 </ b> A ′ (two in the illustrated example) are seen in the feeding direction when viewed in the axial direction of the air feeding pipe. The fuel gas inlet pipe 29 ′ is connected to each fuel gas inlet 29 A ′ so as to be tangential to the outer pipe 26 so as to be offset from the axis of the outer pipe 26. By doing so, the fuel gas produces a swirling flow in the outer tube 26, and the degree of mixing with air, oxygen and dust in the tip region of the outer tube 26 is increased.

  Further, in the form of FIG. 4, it is not essential to generate a swirling flow in the outer tube 26. When such a swirling flow is not particularly necessary, the fuel gas inlet 29A 'may be provided at a position that does not deviate from the axis of the outer pipe 26, similarly to the oxygen inlet 29A in the form of FIG. In this case, it is also possible to provide the fuel gas inlets 29A 'at a plurality of positions in the circumferential direction of the outer tube 26.

  In addition, when a plurality of fuel gas inlets 29A ′ are provided regardless of whether or not a swirl flow is generated, the fuel gas inlets 29A ′ are surrounded so as to be the same as described with reference to the embodiment of FIG. Alternatively, a jacket that forms an annular space may be attached to the outer pipe 26, and the fuel gas inlet pipe may be connected to one place in the circumferential direction of the jacket. By providing such a jacket, the fuel gas fed from one fuel gas inlet pipe is dispersed in the jacket and uniformly enters the outer pipe 26 from the plurality of fuel gas inlets 29A ′. Go around in the circumferential direction. By adopting a mixed gas blowing device having a jacket in this manner, the pipe system for supplying fuel gas is simplified.

  In the form of FIG. 4, it is preferable that the flow rate of air in the inner pipe 27 is 70 to 120 m / sec, and the flow speed at which oxygen is fed from the oxygen feed inlet 24A ′ to the inner pipe 27 is 50 to 200 m / sec. By setting the flow velocity in such a range, oxygen, air, and fuel gas can be mixed efficiently, and the mixed gas can reach the preferred range of the coke bed in the furnace from the tuyere, in the coke bed. Fuel gas combustion can be performed satisfactorily.

DESCRIPTION OF SYMBOLS 1 Waste gasification melting furnace 5 (Main) tuyere 20 Mixed gas blowing apparatus 22 Air supply pipe 23A Dust supply port 24A Fuel gas inlet 24A 'Oxygen inlet 29A Oxygen inlet 29A' Fuel gas inlet 26 Outer pipe 27 In tube

Claims (12)

Oxygen, air, fuel gas, and waste gasification and melting furnace were discharged and recovered to the coke floor of the waste gasification and melting furnace, where the waste is pyrolyzed and the residue is melted in the furnace with a coke bed In the mixed gas blowing device for blowing the mixed gas mixed with dust from the tuyere provided in the furnace body of the waste gasification melting furnace,
An air supply pipe connected to the tuyere and sending the mixed gas into the furnace body, and the air supply pipe has an outer pipe and an inner pipe having a tip opening located upstream of the tip opening of the outer pipe. The inner pipe is supplied with air and the outer pipe is supplied with oxygen, and the inner pipe has at least one branch port at each of two different axial positions. A branch port located on the upstream side of the two positions is formed as a dust supply port for supplying dust to the air flowing in the inner tube, and is formed on the outer peripheral surface of the tube. The branch port located on the side is formed as a fuel gas inlet for sending fuel gas into the air, and the air and fuel are reached by the end of the inner pipe until the position of the tip opening of the inner pipe. After the gas and dust are mixed, the oxygen in the outer tube is reduced at the tip region in the outer tube. Are mixed in Les mixed gas blowing apparatus characterized by being adapted to the mixed gas is formed.   The outer pipe of the air supply pipe has branch ports formed at a plurality of positions in the circumferential direction, and these branch ports are formed as oxygen inlet ports for sending oxygen into the outer pipe. 2. The mixed gas blowing device according to claim 1, wherein the air supply pipe has a jacket that forms an annular space that communicates and covers these oxygen inlets. Oxygen, air, fuel gas, and waste gasification and melting furnace were discharged and recovered to the coke floor of the waste gasification and melting furnace, where the waste is pyrolyzed and the residue is melted in the furnace with a coke bed In the mixed gas blowing device for blowing the mixed gas mixed with dust from the tuyere provided in the furnace body of the waste gasification melting furnace,
It has an air supply pipe for sending the above mixed gas into the furnace body, its tip attachment part is provided at the tip of the air supply pipe for attachment to the tuyere, and the tip attachment part is in the through hole of the tuyere formed in the furnace wall A base-like holding body is attached to hold the tip mounting portion with the inner peripheral surface of the furnace inner end contacting the outer peripheral surface of the furnace outer end of the tip mounting portion. The mounting portion is formed with a cylindrical through hole, and the inner peripheral surface of the outer end portion of the cylindrical through hole is in contact with the outer peripheral surface of the inner end portion of the air supply tube to hold and hold the air supply tube. At least the holding body of the body and the tip mounting part is water-cooled,
The air supply pipe has a double pipe structure having an outer pipe and an inner pipe whose tip opening is located upstream of the tip opening of the outer pipe. Air is supplied to the inner pipe and fuel gas is supplied to the outer pipe. Furthermore, the inner pipe is formed with at least one branch port opened in the outer peripheral surface of the inner pipe at each of two different positions in the axial direction, The branch port located on the upstream side is formed as a dust supply port for supplying dust to the air flowing in the inner pipe, and the branch port located on the downstream side is for sending oxygen into the air. Each position is formed such that the distance from the oxygen inlet to the inner tube tip opening in the axial direction of the air pipe is longer than the distance from the inner tube tip opening to the outer tube tip opening. defined, leading to the position of the distal end opening of the inner tube at the inner tube or Air in the space range of, after the oxygen and dust are mixed, in a space ranging from the distal end opening of the inner tube of the outer tube to the furnace inner end of the cylindrical penetration of the tip mounting portion, the outflow from the inner tube A mixed gas blowing device characterized in that fuel gas is mixed with mixed air, oxygen and dust to form the mixed gas.   The air supply pipe is formed by opening a branch port as a fuel gas inlet on the outer peripheral surface of the outer pipe, and the fuel gas is supplied from the fuel gas inlet when viewed in the axial direction of the air pipe. The direction is deviated with respect to the axis of the outer pipe, and the fuel gas fed in the tangential direction of the outer pipe from the fuel gas inlet is configured to generate a swirling flow in the outer pipe. The mixed gas blowing device according to claim 3.   4. The air supply pipe according to claim 3, wherein fuel gas inlets are formed at a plurality of positions in the circumferential direction, and have a jacket that forms an annular space that communicates and covers these fuel gas inlets. The mixed gas blowing device according to claim 4.   A waste gasification and melting furnace comprising the mixed gas blowing device according to any one of claims 1 to 5. Oxygen, air, fuel gas, and waste gasification and melting furnace were discharged and recovered to the coke floor of the waste gasification and melting furnace, where the waste is pyrolyzed and the residue is melted in the furnace with a coke bed In the mixed gas blowing method of blowing the mixed gas mixed with dust from the tuyere provided in the furnace body of the waste gasification melting furnace,
An air supply pipe that is connected to the tuyere and sends the mixed gas into the furnace body is connected, and the air supply pipe includes an outer pipe and an inner pipe having a tip opening located upstream of the tip opening of the outer pipe. The inner tube is supplied with air and the outer tube is supplied with oxygen, and the inner tube has at least one branch port at each of two different axial positions. It is formed by opening in the outer peripheral surface of the inner pipe, and the branch port located upstream of the two positions is used as a dust supply port, and dust is supplied to the air flowing in the inner tube from the dust supply port. The branch port located on the downstream side is used as a fuel gas inlet, and the fuel gas is sent into the air from the fuel gas inlet, and the inner pipe reaches the position of the tip opening of the inner pipe. After mixing air, fuel gas, and dust, the outer end of the outer pipe Mixed gas blowing method by mixing of oxygen thereto and forming the mixed gas.   The outer pipe of the air supply pipe has branch ports formed at a plurality of positions in the circumferential direction, and these branch ports are formed as oxygen inlet ports for sending oxygen into the outer pipe. The air supply pipe has a jacket that forms an annular space that communicates and covers these oxygen inlets, and oxygen is supplied from each oxygen inlet into the outer pipe through the annular space. The mixed gas blowing method described. Oxygen, air, fuel gas, and waste gasification and melting furnace were discharged and recovered to the coke floor of the waste gasification and melting furnace, where the waste is pyrolyzed and the residue is melted in the furnace with a coke bed In the mixed gas blowing method of blowing the mixed gas mixed with dust from the tuyere provided in the furnace body of the waste gasification melting furnace,
Connected to the tuyere and connected to the air feed pipe that sends the mixed gas into the furnace, and attached to the tip of the air feed pipe for attachment to the tuyere and the through hole of the tuyere Among the holding bodies that hold the tip mounting portion, at least the holding body is water-cooled, and the air supply pipe has an outer pipe and an inner pipe whose tip opening is located upstream of the tip opening of the outer pipe. It has a double pipe structure and supplies air to the inner pipe and fuel gas to the outer pipe. Further, the inner pipe has at least one branch port at each of two different positions in the axial direction. An opening is formed in the outer peripheral surface of the inner pipe, and a branch port located upstream of the two positions is used as a dust supply port, and dust is supplied from the dust supply port to the air flowing in the inner tube. The branch port located on the downstream side is used as the oxygen inlet to the air. The iodine was fed from the inlet feed the oxygen, feeding oxygen inlet port in the axial direction of the trachea distance to the inner tube distal end opening, the inner tube from the distal end opening outer tube distal end opening until the longer becomes as in the respective than the distance After mixing air, oxygen, and dust in a space in the inner pipe where the position is determined, up to the position of the tip opening of the inner pipe , Fuel gas is mixed with the mixed air, oxygen, and dust flowing out from the inner pipe in the space up to the furnace inner end of the cylindrical through hole to form the mixed gas, and the air velocity in the inner pipe Is fed at 70 to 120 m / sec, and the flow rate of oxygen from the oxygen inlet to the inner tube is 50 to 200 m / sec .   The air supply pipe is formed by opening a branch port as a fuel gas inlet on the outer peripheral surface of the outer pipe, and the fuel gas is supplied from the fuel gas inlet when viewed in the axial direction of the air pipe. The direction is deviated with respect to the axis of the outer pipe, and the fuel gas is fed in the tangential direction of the outer pipe from the fuel gas inlet to generate a swirling flow in the outer pipe. The mixed gas blowing method described.   The air supply pipe has fuel gas inlets formed at a plurality of positions in the circumferential direction, and has a jacket that forms an annular space that communicates and covers these fuel gas inlets. The mixed gas blowing method according to claim 9 or 10, wherein the gas is fed into each outer gas pipe from each fuel gas inlet.   The mixed gas blowing method according to any one of claims 7 to 11, wherein the mixed gas is blown into the furnace body toward the coke bed of the waste gasification and melting furnace, and the waste is thermally decomposed to melt the residue. A waste gasification melting method characterized by the above.

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