JP6331149B2 - Waste gasification and melting apparatus and waste gasification and melting method - Google Patents

Description

  The present invention relates to a waste gasification and melting apparatus and a waste gasification and melting method for pyrolyzing, gasifying, and burning waste and melting residual ash.

  Waste melting treatment using a waste gasification melting furnace that processes waste such as municipal waste and shredder dust by pyrolyzing, gasifying, and burning the waste to melt the remaining ash into slag It has been known.

  This treatment method can recover the amount of heat by pyrolyzing and gasifying waste, and reducing the amount that should be finally disposed of in landfills after melting the ash and discharging it as slag. Has the advantage that can be. 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 and melting furnace, for example, burns coke deposited in the lower part of the furnace, throws the waste on this high-temperature coke bed, pyrolyzes and gasifies it, and removes residual ash It is a furnace that performs a process of melting into slag (see Patent Document 1).

  In the shaft furnace type waste gasification and melting furnace of Patent Document 1, the functions of the vertical cylindrical furnace body are roughly divided into three regions in the vertical (vertical) 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 waste gasification and 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 lower part of the furnace, and oxygen-enriched air is blown into the furnace through an air pipe connected to the main tuyere, and the coke deposited and deposited in the high-temperature combustion zone The coke in the floor burns and serves as a heat source for melting ash. In addition, the waste layer is provided with a sub tuyere, air is blown in, and the waste deposited and flowed gently, and the waste is thermally decomposed, partially oxidized and gasified. In addition, the free board part is provided with a three-stage tuyere, air is blown in, and a part of the pyrolysis gas (combustible gas) generated by pyrolyzing the waste is partially burned to bring the inside to a predetermined temperature. maintain.

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 and gasified to produce gas and ash. Coke on the coke floor is combusted by blowing oxygen-enriched air from the main tuyere to form a high-temperature combustion zone, and the ash content 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 pyrolyzed and gasified by blowing air from the sub tuyere. The gas containing the combustible gas generated by this pyrolysis rises in the waste layer, and is discharged to the secondary combustion chamber outside the furnace through the free board portion and the discharge port provided in the upper part of the furnace. . 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. The gas discharged from the boiler removes relatively coarse dust with a cyclone,
Further, the gas is cooled by a temperature reducing device, the harmful gas is removed by reaction with the harmful substance removing agent, exhaust gas treatment such as dust removal treatment by a dust collector, and then emitted 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 ash. There is a need to reduce emissions.

  Therefore, it is considered to use fuel gas such as natural gas, propane gas, and combustible gas generated by thermal decomposition in a waste gasification and melting furnace as an alternative to coke. It has been proposed to inject fuel gas along with oxygen-enriched air from the tuyere.

JP 09-060830 A JP 2001-090923 A

  In order to reduce the amount of carbon dioxide emitted, in order to reduce the amount of coke used in a waste gasification and melting furnace, when fuel gas is blown into the furnace from the main tuyere as an alternative to part of coke as in Patent Document 2 Then, several problems arise under the following circumstances.

  When fuel gas is supplied from the main tuyere of the waste gasification melting furnace and burned, a mixture of fuel gas and oxygen-enriched air mixed in advance outside the furnace is used at the tip of the feed pipe at a speed exceeding the flame propagation speed. From the following points, premixed combustion is preferably performed by supplying the fuel into the furnace.

  In waste gasification and melting furnaces, powder such as ash, dust, and pulverized fuel may be supplied from the main tuyere through the air pipe, but the diameter is large to prevent clogging of the powder in the air pipe. It is desirable to convey the powder with a high flow rate gas using this pipe. For this purpose, a premixed combustion system in which a mixed gas in which the total amount of gas is premixed is supplied to the main tuyere with an air pipe formed by a single pipe is suitable.

  In the case of performing premixed combustion, the mixed gas is blown into the furnace from the tuyere at a speed exceeding the flame propagation speed of the mixed gas, preferably 5 times or more the flame propagation speed. By doing so, the fuel gas is not ignited in the air supply pipe into which the mixed gas is blown, and the fuel gas blown in from the air supply pipe is ignited in the furnace. It has been found that ignition may occur and vibration combustion may occur in the air pipe.

  When vibration combustion occurs in the air pipe, the combustion speed fluctuates remarkably in time, the combustion pressure fluctuates greatly and pulsation occurs, so that the combustion is not stable and the air pipe may be damaged.

  The tip of the air pipe is installed in the water-cooled main tuyere, but the air pipe is for supplying preheated gas. From this point of view, active cooling is not performed. . Under normal air supply in which no oscillating combustion occurs, the preheating temperature of the mixed gas is lower than the ignition temperature, so that the air supply pipe is cooled by the flow of the mixed gas.

However, due to worsening of the furnace conditions (for example, stagnant decline of waste and uneven ventilation of oxygen-enriched air and combustion gas in the furnace), good combustion at the tuyere It cannot be maintained, and molten slag may not be able to flow well. High-viscosity slag that is not sufficiently heated forms a blockage with surrounding solids.If flame or red-hot coke or molten slag approaches or comes into contact with the tip of the air pipe, the air pipe tip is heated and the ignition temperature is reached. The fuel gas is ignited at the tip of the air pipe, and the flame formed at the tip of the air pipe heats the inner wall of the air pipe around the tip to raise the temperature to the ignition temperature, toward the upstream side of the air pipe. When the ignition position moves on the inner wall of the air supply pipe and the fuel gas burns in the air supply pipe, vibration combustion occurs. When vibration combustion occurs in the air supply pipe, there arises a problem that the combustion of the fuel gas in the furnace cannot be stably performed and a problem that the air supply pipe is damaged.

  In view of such circumstances, the present invention can stably burn in a furnace without causing ignition in the air pipe even if the fuel gas is mixed with oxygen-enriched air and blown into the main tuyere. It is an object of the present invention to provide a waste gasification and melting apparatus and a waste gasification and melting method.

  According to the present invention, the waste gasification and melting apparatus and the waste gasification and melting method are configured as follows.

<Waste gasification and melting equipment>
A shaft furnace type waste gasification and melting furnace which receives waste input, pyrolyzes, gasifies and burns the waste, and melts the remaining ash, and a mixed gas in which fuel gas is mixed with oxygen-enriched air In a waste gasification and melting apparatus comprising a mixed gas blowing device for blowing from the main tuyere provided at the lower part of the waste gasification and melting furnace, the mixed gas blowing apparatus is connected to the main tuyere and the mixed gas is fed into the furnace A waste gasification and melting apparatus, comprising: an air supply pipe to be fed to the inside of the furnace, and a cooling portion for cooling an end portion of the air supply pipe inside the furnace.

<Waste gasification and melting method>
The waste gas is put into a shaft furnace type waste gasification melting furnace, the waste is pyrolyzed, gasified, burned, the remaining ash is melted, and the mixed gas in which oxygen-enriched air and fuel gas are mixed is In a waste gasification and melting method having a mixed gas blowing process for blowing from a main tuyere provided at the lower part of a waste gasification and melting furnace, the mixed gas blowing process is connected to the main tuyere and the mixed gas is fed into the furnace A waste gasification and melting method comprising a cooling step of cooling an inner end portion of an air feeding pipe to be sent.

  According to the waste gasification and melting apparatus and method of the present invention having such a configuration, the end portion inside the furnace of the air supply pipe is cooled by the cooling section. Therefore, the end of the air pipe inside the furnace is kept lower than the ignition temperature of the mixed gas of oxygen-enriched air and fuel gas, and as a result, there is no ignition of the mixed gas at the end of the air pipe. Also, vibration combustion does not occur.

  In the present invention, the cooling of the air supply pipe by the cooling section is preferably performed by cooling the end of the air supply pipe inside the furnace within a range of 20 to 100 mm from the tip.

  In the present invention, the cooling of the air pipe by the cooling section is preferably performed by cooling the end of the air pipe inside the furnace to a temperature lower than the ignition temperature of the mixed gas by 50 ° C. or lower or 300 ° C. or lower.

  In the present invention, the main tuyere is in contact with the outer peripheral surface of the air supply tube and holds the inner end of the air supply tube in the furnace, and the main tuyere is in contact with the outer peripheral surface of the tuyere main body and A holding body attached to the furnace wall in a state of holding the mouth body, the tuyere body is formed as a cooling part with a hollow channel for the flow of the cooling medium, and the tip of the air feeding pipe is connected to the air feeding pipe. In the axial direction, it is immersed behind the tip position of the tuyere body and is located in the axial range of the cooling unit, and the inner diameter surface of the tuyere body forms an exposed surface ahead of the tip position of the air supply tube. Can be. In this case, it is preferable that the tuyere body has a tapered surface whose inner diameter surface is further forward than the tip position of the air supply tube.

  In the present invention, when the air supply pipe is provided with a dust supply port for supplying dust in the exhaust gas from the waste gasification melting furnace into the air supply pipe, the tapered surface of the tuyere body is resistant to dust. It is preferable that a wear-resistant layer of a material having wear properties is formed.

  In the present invention, the taper angle of the taper surface is preferably 20 ° to 40 °.

According to the waste gasification and melting apparatus and the gasification and melting method of the present invention, the main wing provided in the lower part of the waste gasification and melting furnace is a mixed gas obtained by mixing oxygen-enriched air and fuel gas. The mixed gas blowing device blown from the mouth has an air supply pipe connected to the main tuyere to send the mixed gas into the furnace, and a cooling section for cooling the inner end of the air supply pipe. Since the inner end is cooled to a temperature lower than the ignition temperature of the mixed gas, it can be prevented that the mixed gas ignites in the air supply pipe and vibration combustion occurs, and the mixed gas is used as an ignition source such as coke in the furnace. It can be ignited and burned stably in the furnace.

  In this way, the fuel gas can be stably burned without causing vibration combustion in the air supply pipe, so that the fuel gas can be used as a substitute for a part of coke and the combustion heat can be stably used as a melting heat source. Therefore, 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. It is an expanded sectional view about the main tuyere applicable to the device of Drawing 1 as other embodiments.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The waste gasification and melting apparatus of the present embodiment includes a shaft furnace type waste gasification and melting furnace 1 that receives supply of coke and fuel gas as fuel, pyrolyzes and gasifies waste, and melts remaining ash. A mixed gas in which a mixed gas in which oxygen-enriched air, fuel gas, and dust discharged from the waste gasification melting furnace are mixed is blown into the lower part of the waste gasification melting furnace 1 from the main tuyere Although it has the blowing apparatus 20, it is characterized before having demonstrated, The outline structure of this shaft furnace type waste gasification melting furnace 1 is demonstrated based on FIG. 1 before description about these characteristics.

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

  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 fed into the furnace through the charging port 2 at the top of the furnace.

  A secondary combustion chamber 10 is connected to the gas discharge port 3 and burns combustible gas generated by pyrolyzing and gasifying waste. The secondary combustion chamber 10 is provided with an air blowing port 11 for blowing air for secondary combustion. 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.

  The shaft furnace type waste gasification and melting furnace 1 has an internal space of the waste gasification and melting furnace 1 divided into four regions in the vertical direction, and from below, a coke packed bed A, a moving bed B, A gasification layer C and a free board portion D are formed.

  In such a waste gasification and melting furnace 1, tuyere is provided in each of the coke packed bed A and the gasification bed C, and oxygen-containing gas is blown into the furnace.

  A main tuyere 5 is provided in the coke packed bed A in the lower part of the furnace, and oxygen-enriched air is blown into the main tuyere. The gasification layer C is provided with a sub tuyere 6 and air is blown in.

  In the lower part of the secondary combustion chamber 10 and the boiler 12, the dust is fed back to the dust storage tank 16 when the exhaust gas is contained in the exhaust gas when passing through the secondary combustion chamber 10 and the boiler 12. A pipe forming a path 15 is connected, and the dust storage tank 16 is connected to a mixed gas blowing device 20 described later via a rotary valve 16A provided at a lower outlet of the dust storage tank.

  The dust contained in the exhaust gas and falling in the secondary combustion chamber 10 and the boiler 12 is discharged from the secondary combustion chamber 10 and the boiler 12, and together with the dust collected by the dust collector, the aforementioned dust return path. 15, a dust supply pipe provided in an air supply pipe 22 which forms a part of a mixed gas blowing device 20 described later attached to the main tuyere 5 through a rotary valve 16 </ b> A after being brought to the dust storage tank 16. The dust is fed back to the furnace.

<Mixed gas blowing device>
As shown in FIG. 2, the mixed gas blowing device 20 includes an air supply pipe 22 connected to the main tuyere 5 so as to send the mixed gas in which the oxygen-enriched air, fuel gas, and dust are mixed into the furnace, A cooling unit 30 in which a cooling medium for cooling the end of the air supply tube 22 inside the furnace flows is provided.

  As described above, the mixed gas blowing device 20 has an air supply pipe 22 that is connected to the main tuyere 5 and sends the mixed gas into the furnace body. The air supply pipe has an oxygen enrichment in the axial direction of the air supply pipe 22. An oxygen-enriched air supply pipe 26 for feeding the conditioned air is connected, and at least one branch port at each of two different positions in the axial direction of the air supply pipe 22 is the outer peripheral surface of the air supply pipe 22. A branch port located on the upstream side of the two positions is a dust for supplying dust from the dust supply pipe 23 to the oxygen-enriched air flowing in the air supply pipe 22. The branch port formed as the supply port 23A and located on the downstream side is formed as a fuel gas inlet port 24A for feeding the fuel gas from the fuel gas inlet tube 24 into the oxygen-enriched air.

  A dust supply pipe 23 that forms part of the dust return path 15 (see FIG. 1) and supplies dust to the air supply pipe 22 is connected to the dust supply port 23A. The fuel gas inlet 24A is connected to a fuel gas inlet 24 for feeding a fuel gas such as natural gas into the inlet 22.

  In the pipe space in the range between the fuel gas inlet 24A and the main tuyere 5 in the axial direction, oxygen-enriched air, fuel gas, and dust are mixed to form the mixed gas. ing. Thus, a mixed gas obtained by mixing oxygen-enriched air, fuel gas, and dust discharged from the waste gasification melting furnace 1 and provided in the lower part of the waste gasification melting furnace 1 is provided. It is blown from the tuyere 5. Since the end portion (tip portion) inside the furnace of the air supply tube 22 is cooled to a temperature lower than the ignition temperature of the mixed gas by the cooling unit 30, the mixed gas is blown into the air supply tube 22 when the mixed gas is blown into the furnace. It is possible to prevent the occurrence of vibration combustion by igniting in the interior, and the mixed gas can be ignited by using coke in the furnace as an ignition source and stably combusted in the furnace.

  The main tuyere 5 provided in the lower part of the furnace wall 1A of the waste gasification melting furnace 1 has a conical shape attached to a stepped taper through hole 1B formed in the furnace wall 1A as seen in FIG. It has a cap-shaped holding body 18 having an outer peripheral surface, and the holding body 18 holds the tuyere body 21 with its inner diameter. The tuyere body 21 is connected to the air supply tube 22 of the mixed gas blowing device 20 and holds the tip of the air supply tube 22 and functions to blow the mixed gas into the furnace.

  The tuyere body 21 has an outer diameter surface 21A tapered and a cylindrical through hole 21B. The holding body 18 that holds the tuyere body 21 has a conical hook shape as described above, and a holding hole 18A is formed at the small diameter side end portion (right end portion in the drawing). The holding hole 18A forms a tapered hole that matches the large-diameter end side portion of the outer diameter surface 21A of the tuyere body 21, and is in contact with the outer diameter surface 21A of the tuyere body 21 through this tapered hole. The tuyere body 21 is held. Thus, the tuyere body 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 tuyere body 21 has a small outer diameter tip. Located in the rush. The tuyere main body 21 that is held by the holding body 18 and holds the tip of the air supply pipe 22 has a cooling structure through which a cooling medium circulates. Omitted. Here, the air supply tube 22 is held by the water-cooled tuyere body 21, but the conventional configuration to which the present invention is applied does not require cooling of the air supply tube, so that the air supply tube 22 has a minimum contact. In some cases, the temperature of the inner wall of the tip of 22 rose to 500 ° C or higher.

  A cooling unit 30 through which water as a cooling medium flows is formed around the inner end of the air supply tube 22. The cooling part 30 has an annular part surrounding the outer peripheral surface of the inner end of the air feeding tube 22 and cools the end of the inner side of the air feeding pipe 22 by circulating cooling water therein. Yes. The cooling unit 30 is preferably a water-cooled system, but other fluid may be used as a refrigerant.

  The cooling unit 30 preferably cools the axial range from 20 to 100 mm from the tip inside the furnace of the air supply tube 22. If the range to be cooled is shorter than 20 mm from the tip inside the furnace, it is difficult to sufficiently cool the tip inside the furnace of the air supply tube 22, and there is a possibility that ignition of the mixed gas occurs in the air supply tube 22. When the range to be cooled is longer than 100 mm from the tip inside the furnace, the mixed gas is excessively cooled from the inner surface of the air supply tube 22, the temperature of the mixed gas is lowered, and it is impossible to quickly ignite in the furnace Occurs.

  In addition, the cooling unit 30 preferably cools the end of the air pipe 22 inside the furnace to a temperature lower than the ignition temperature of the mixed gas by 50 ° C. or lower, or 300 ° C. or lower. If the temperature at which the end of the air pipe 22 inside the furnace is cooled is higher than a temperature lower by 50 ° C. than the ignition temperature of the mixed gas, or higher than 300 ° C., depending on the part of the end of the air pipe 22 inside the furnace. There are places where the temperature becomes equal to or higher than the ignition temperature of the mixed gas, and the mixed gas may be ignited in the air supply pipe 22.

  In the present embodiment configured as described above, waste gasification and melting treatment of waste is performed in the following manner.

<Gas melting method in waste gasification melting furnace>
Waste, coke, and limestone from the supply device are respectively charged into the furnace by a predetermined amount through the inlet 2 provided in the upper part of the waste gasification melting furnace 1, from the main tuyere 5 and the sub tuyere 6. , Oxygen-enriched air and air are blown into the furnace, respectively. In particular, from the main tuyere 5, as described above, a mixed gas obtained by mixing oxygen-enriched air, fuel gas, and dust in the air supply pipe 22 of the mixed gas blowing device 20 is blown into the furnace.

  Waste introduced from the inlet 2 accumulates in the furnace to form a gasification layer C of waste, and from the high temperature combustion gas and the sub tuyere 6 rising from the moving bed B at the lower part of the furnace. It is heated by the combustion gas from the blown air, dried and then pyrolyzed. Combustion gas containing combustible gas generated by pyrolysis rises, a part of the combustible gas is combusted in freeboard part D, maintains the inside of the furnace at a predetermined temperature, and harmful substances and tar generated by pyrolysis Processing to decompose the minutes is performed. The gas that has passed through the free board part D is discharged from the discharge port provided in the upper part of the furnace to the secondary combustion chamber 10 outside the furnace. The gas contains a large amount of combustible gas, and air is blown into the secondary combustion chamber 10 through the air blowing port 11 and burned, and heat is recovered from the combustion gas in the boiler 12 to generate steam, which is used for power generation and the like. It is done. The gas discharged from the boiler 12 has relatively coarse dust removed by a cyclone (not shown), further cooled by a temperature reducing device (not shown), and removed by reaction with a hazardous substance remover. Then, after exhaust gas treatment such as dust removal with a dust collector (not shown), it is emitted from the chimney (not shown) to the atmosphere.

The waste is thermally decomposed in the gasification layer C to generate gas, and the fixed carbon and ash generated by the thermal decomposition descend together with the coke and limestone to form the moving layer B. In the moving bed B, the solids that are lowered by the high-temperature gas rising from the coke packed bed A are heated, and at the same time, the fixed carbon generated by the pyrolysis of the waste by the high-temperature CO ₂ gas is gas. It becomes. In the coke packed bed A, the oxygen-enriched air blown from the main tuyere 5 burns coke and fuel gas and the remaining fixed carbon of the waste that is not gasified, and the combustion heat melts the ash content of the waste. Molten slag and molten metal are produced. Limestone works as a conditioner that makes the slag melted with ash preferable. Further, the generated high-temperature combustion gas rises and becomes a heat source for heating for thermal decomposition of the waste.

  In the lower part of the furnace below the main tuyere 5, coke packed bed A is formed in a state in which coke which is high in temperature but not burned out is filled while maintaining a gap between the coke lumps. Molten slag and molten metal Drops the gap between coke lumps and reaches the bottom of the furnace. The molten slag and molten metal are homogenized by the time they reach the bottom of the furnace, their properties are stabilized, discharged from the tap 4 provided at the bottom of the furnace, and supplied to a water granulator (not shown) provided outside the furnace. The supplied granulated slag and granulated metal are recovered by cooling and solidifying. Oxygen-enriched air blown from the main tuyere 5 and high-temperature combustion gas generated by the combustion of coke, fuel gas, and fixed carbon rise from the coke packed bed A to the gasified bed C through the moving bed B Then, the waste is heated, and the waste of the gasification layer C is partially oxidized, pyrolyzed, and gasified by the air supplied from the sub tuyere 6. In the coke packed bed A, coke and fuel gas are burned to become a heat source for ash melting and waste pyrolysis, and the coke keeps the gaps between the lumps and ventilates the oxygen-enriched air and the high-temperature combustion gas to melt It has the function of a high-temperature grate that allows slag and molten metal to flow.

  When the dust in the mixed gas blown from the main tuyere reaches the coke packed bed A from the main tuyere 5, it melts and drops the coke packed bed together with the waste ash melt, and the outlet 4 at the bottom of the furnace. Extracted as molten slag. As described above, the volume of the landfill can be reduced by melting the dust, and the amount of landfill disposal can be greatly reduced as compared with the case of landfill disposal with dust.

  In the present embodiment, the oxygen-enriched air, the fuel gas, and the dust are sufficiently mixed in the furnace by the mixed gas blowing device 20 in the space on the downstream side of the fuel gas inlet 24 </ b> A in the air supply pipe 22. To be blown into. Therefore, the fuel gas is in a mixed gas state that is sufficiently mixed with the oxygen-enriched air before being blown out from the main tuyere 5 into the furnace, and the combustion of the fuel gas in the coke packed bed A is performed well. Is called.

  In the present embodiment, the mixed gas blowing device 20 further includes a cooling unit 30 that cools the end portion of the air supply tube 22 inside the furnace, and the end portion of the air supply tube 22 inside the furnace is ignited with the ignition temperature of the mixed gas. Since the mixture gas is cooled to a lower temperature, it is possible to prevent the mixed gas from being ignited in the air supply pipe 22 and causing vibration combustion, and the mixed gas can be ignited by using coke in the furnace as an ignition source and stably combusted.

  In this way, the fuel gas can be stably combusted without causing vibration combustion, so the fuel gas can be used as a substitute for a part of coke and the combustion heat can be stably used as a melting heat source. The amount of carbon dioxide emissions can be reduced by reducing the amount used.

  In the present invention, the flow rate of oxygen-enriched air when flowing from the oxygen-enriched air supply pipe 26 into the air supply pipe 22 is set to 70 to 120 m / sec, and the fuel gas when flowing into the air supply pipe 22 from the fuel gas inlet 24A. The flow rate is preferably 50 to 200 m / sec. By setting the flow rate in such a range, the oxygen-enriched air and the fuel gas can be mixed efficiently, and the mixed gas can reach the preferred range of the moving bed in the furnace from the tuyere. The fuel gas combustion can be performed satisfactorily.

<Main tuyere applied as another embodiment>
Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment of FIG. 3, the main tuyere 5 is in contact with the outer peripheral surface of the air supply tube 27 and holds the end portion inside the furnace of the air supply tube 27, and the outer surface of the tuyere main body 28. And a holding body 29 attached to the furnace wall in a state of holding the tuyere body 28 in contact with the surface. The tuyere main body 28 is formed with a hollow flow path for the flow of the cooling medium as the cooling unit 30, and the tip of the air supply pipe 27 is behind the tip position of the tuyere main body 28 in the axis X direction of the air supply pipe 27. It is immersed and is located in the range of the cooling unit 30 in the axis X direction, the inner diameter surface of the tuyere body 28 forms an exposed surface ahead of the tip position of the air supply tube 27, and the tip of the air supply tube 27 A tapered surface 28A is formed toward the front of the position.

  The cooling unit 30 extends in the direction of the axis X to the range of the tapered surface 28A. Therefore, the tapered surface 28A exposed to the high temperature gas in the furnace and exposed to the high temperature atmosphere is the cooling medium of the cooling unit 30 from the inside. It will be cooled by. The tip of the air supply tube 27 is immersed behind the tip position of the tuyere main body 28 in the direction of the axis X of the air supply tube 27 so as not to contact the high temperature gas in the furnace, and the tapered surface 28A is cooled. Therefore, the mixed gas blown into the furnace along the tapered surface 28A from the inside of the air supply pipe 27 does not reach the ignition temperature, and the mixed gas is prevented from being ignited in the air supply pipe 22 to generate vibration combustion. In addition, the mixed gas can be ignited using coke in the furnace as an ignition source, and can be combusted stably.

  The distal end of the air supply tube 27 is immersed in the direction of the axis X of the air supply tube 27 by 20 to 100 mm, more preferably 40 to 70 mm behind the tip position of the tuyere body 28, so that the distal end of the air supply tube 27 is in the furnace. It is possible to avoid exposure to a high temperature gas in the inside, exposure to a high temperature atmosphere, heating by radiant heat, and heating due to contact with a high temperature solid or melt, and an increase in the temperature of the inner wall near the tip of the air supply pipe 27. And the temperature of the mixed gas can be kept below the ignition temperature. If the tip position of the air supply tube 27 is shorter than 20 mm from the tip position of the tuyere body 28, it is difficult to suppress the rise in the inner wall temperature near the tip of the air supply tube 27, and the mixed gas is ignited in the air supply tube 22. If the tip position of the air supply tube 27 is longer than 100 mm from the tip position of the tuyere body 28, the mixed gas is excessively cooled from the inner diameter surface of the tuyere body 28, and the temperature of the mixed gas Decreases, and it is impossible to ignite quickly in the furnace.

  The taper angle θ of the tapered surface 28A is preferably 20 ° to 40 °, and more preferably about 30 °. When the taper angle θ is smaller than 20 °, the blown dust particles collide with the tapered surface 28A and wear occurs. When the taper angle θ is larger than 40 °, the high-temperature gas in the furnace is drawn into the feed pipe side by the circulating flow generated in the tapered portion. It is unsuitable because it becomes.

  Further, a portion of the cooling unit 30 of the tuyere body 28 that is in contact with the tip of the air supply tube 27 is projected radially inward so as to cover the end surface of the air supply tube 27 to protect the end surface of the tip of the air supply tube 27. By doing so, the end face can be prevented from being heated by radiation from the inside of the furnace, and the temperature rise at the tip of the air supply tube 27 can be further prevented.

  The tapered surface 28 </ b> A is preferably formed with a wear-resistant layer made of a material that is resistant to dust contained in the mixed gas blown out from the air supply pipe 27. The wear-resistant layer can be obtained, for example, by spraying WC (tungsten carbide) or CrC (chromium carbide) together with a binder metal to form a film having a thickness of about 100 to 500 μm.

  The cooling part 30 formed as a hollow flow path for the refrigerant flow inside the tuyere body 28 extends to the vicinity of both ends of the tuyere body 28 in the axis X direction. Two holes are formed in the closing wall at the left end in the axis X direction. The upper hole is used as the refrigerant inlet 31A, and the lower hole is used as the outlet 31B. The hollow channel is divided into upper and lower spaces by a partition wall (not shown) extending in a direction orthogonal to the paper surface in FIG. 3, and the partition wall has a nonexistence area or a through hole at the right end. Therefore, the refrigerant flowing in from the inlet 31A flows through the upper space in the right end (tip) direction, then reaches the lower space at the right end, flows to the left, and flows from the outlet 31B. The structure of the refrigerant flow path of the cooling unit 30 is not limited to this, and any structure that can effectively cool the tuyere body 28. In Fig. 3, a pipe that guides the refrigerant to the inlet 31A. Illustration of the conduit leading out of the holding body 29 from the passage and outflow port 31B is omitted.

  Thus, in the present embodiment, the tip of the air supply tube 27 is immersed behind the tip position of the tuyere body 28 so as not to come into contact with the high-temperature gas, solid or melt in the furnace, and the tapered surface 28A is cooled. As a result, the mixed gas does not reach the ignition temperature, and it can be prevented that the mixed gas ignites in the air supply pipe 22 and vibration combustion occurs, and the mixed gas is used as an ignition source such as coke in the furnace. Ignite and burn stably.

DESCRIPTION OF SYMBOLS 1 Waste gasification melting furnace 5 Main tuyere 20 Mixed gas blowing apparatus 30 Cooling part 22 Air supply pipe 27 Air supply pipe
28 tuyere body
29 Holder
X axis
θ taper angle

Claims (6)

A shaft furnace type waste gasification and melting furnace which receives waste input, pyrolyzes, gasifies and burns the waste, and melts the remaining ash, and a mixed gas in which fuel gas is mixed with oxygen-enriched air In a waste gasification and melting apparatus comprising an air feed pipe that is fed into the furnace from the main tuyere provided at the lower part of the waste gasification and melting furnace,
The main tuyere, holding the tuyere body, the該羽port main body facing against the outer peripheral surface of the該羽port body facing against the outer peripheral surface of the feed pipe for holding the end of the furnace inside of the feed pipe A holding body attached to the furnace wall in a state of
The tuyere body has a cooling part in which a hollow channel for the circulation of the cooling medium is formed and cools the tuyere body and the inner end of the air pipe,
The air pipe has its tip immersed behind the furnace inner tip position of the tuyere body, and is located in the axial range of the cooling part of the tuyere body,
The inner diameter surface of the tuyere body has a tapered part exposed from the position inside the furnace inside the air pipe toward the tip of the tuyere body,
The upstream part of the tapered part at the tip of the tuyere body and the part in contact with the tip of the air pipe of the cooling part protrudes inward in the radial direction, and covers and protects the end face of the tip of the air pipe,
Flue is furnace range from inner end to 20~100mm is, 50 ° C. temperature lower than the ignition temperature of the mixed gas by cooling part or 300 ° C. waste gas, characterized that you have been cooled to a temperature below Melting equipment. The air supply pipe is provided with a dust supply port for supplying dust in the exhaust gas from the waste gasification melting furnace into the air supply pipe, and the taper angle of the tapered portion of the tuyere body is 20 ° to 40 °. The waste gasification and melting apparatus according to claim 1 . The waste gasification and melting apparatus according to claim 2 , wherein the tapered portion of the tuyere body is formed with a wear-resistant layer made of a material having wear resistance against dust. The waste gas is put into a shaft furnace type waste gasification melting furnace, the waste is pyrolyzed, gasified, burned, the remaining ash is melted, and the mixed gas in which oxygen-enriched air and fuel gas are mixed is In the waste gasification and melting method having a mixed gas blowing step for blowing from the main tuyere provided at the lower part of the waste gasification and melting furnace,
The inner peripheral surface of the tuyere body is in contact with the outer peripheral surface of the air supply tube, the end of the inner side of the air supply tube is held by the tuyere main body, and the inner peripheral surface of the holding body is on the outer peripheral surface of the tuyere main body. The main tuyere is formed by attaching to the furnace wall in a state where the tuyere body is held by the holding body,
Mixed gas blowing step is to have a cooling step of cooling the the tuyere body and the furnace inner end of the air pipe by circulating a cooling medium into the hollow channel formed as a cooling unit in the tuyere body,
In the cooling step, the tip of the air supply tube is immersed behind the position inside the furnace tip of the tuyere main body to be positioned in the axial range of the cooling part of the tuyere main body, and the inner diameter surface of the tuyere main body is set to The taper is exposed from the position inside the furnace toward the tip of the tuyere body, and the upstream part of the taper at the tip of the tuyere body that is in contact with the tip of the cooling pipe is projected radially inward. The end face of the tip of the air pipe is covered and protected, and the air pipe is within a range of 20 to 100 mm from the tip inside the furnace, a temperature not more than 50 ° C. lower than the ignition temperature of the mixed gas by the cooling section, or a temperature not more than 300 ° C. waste gasification melting method characterized that you cooling. The dust in the exhaust gas from the waste gasification and melting furnace is supplied into the air supply pipe from the dust supply port provided in the air supply pipe, and the taper angle of the tapered portion of the tuyere body is 20 ° to 40 °. The waste gasification melting method according to claim 4. 6. The waste gasification and melting method according to claim 5, wherein the tapered portion of the tuyere body is formed of a wear-resistant layer made of a material that is resistant to dust.

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