JP2019039644A - Incineration plant - Google Patents

Abstract

To provide an incineration plant which prevents incomplete combustion of waste and reduces production quantity of clinker while suppressing the generation of nitrogen oxide preferably in the incineration plant which circulates a part of exhaust gas from an incineration furnace into the incineration furnace as circulation exhaust gas.SOLUTION: An incineration plant includes: an incineration furnace composed of a furnace chamber, a re-combustion chamber, a plurality of stokers and an intermediate partition wall which partitions an upper space of the furnace chamber and an upper space of the re-combustion chamber and is arranged so as to be separated from upper surfaces of the plurality of stokers; a circulation path which circulates a part of exhaust gas as circulation exhaust gas; an injection nozzle which is provided on a position corresponding to the intermediate partition wall and injects the circulation exhaust gas passing through the circulation path into the furnace chamber; and a control device. Therein, the control device controls the injection nozzle so as to inject the circulation exhaust gas from the injection nozzle from the downstream side toward the upstream side in the transport direction and, thereby, inverts the circulation exhaust gas from the furnace chamber toward the intermediate partition wall and an inversion flow of gas which passes through the lower side of the intermediate partition wall and proceeds to the re-combustion chamber is formed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an incineration plant for processing waste such as garbage.

  An incineration plant equipped with an incinerator is known as a waste treatment facility. As a form of the incinerator, for example, a stoker type that burns waste and combustion gas (combustible gas) while conveying waste by a plurality of stokers can be mentioned.

  As an incineration plant, for example, as disclosed in Patent Document 1, a part of exhaust gas from an incinerator is circulated in an incinerator as circulating exhaust (EGR) gas, so that the combustion temperature of waste is excessively increased. In order to prevent this, the generation of nitrogen oxides (NOx) is known.

Japanese Patent Laid-Open No. 2006-75415

  When circulating exhaust gas is circulated in the incinerator, generation of nitrogen oxides is suppressed, but incomplete combustion where the combustion gas temperature in the incinerator decreases and solid unburned waste remains, or incinerator Incomplete combustion may occur in which carbon monoxide (CO) is generated due to insufficient oxygen concentration.

  In the incineration plant, clinker is generated by the combustion ash of the waste and adheres to the furnace wall of the incinerator, which may impede the flow of waste and gas in the incinerator. For this reason, although it is calculated | required to remove a clinker from the furnace wall of an incinerator, the burden of a maintenance operation increases.

  Accordingly, the present invention provides an incineration plant that circulates a part of the exhaust gas from the incinerator as a circulating exhaust gas in the incinerator, while preventing generation of nitrogen oxides and preventing incomplete combustion of waste and clinker. The purpose is to reduce the amount of generation.

  In order to solve the above problems, an incineration plant according to one aspect of the present invention includes a furnace chamber for burning waste, a recombustion chamber for burning combustion gas generated by combustion of waste in the furnace chamber, and the furnace A plurality of stalkers disposed below the chamber and the recombustion chamber and configured to convey waste in a predetermined transport direction, and separates the upper space of the furnace chamber and the upper space of the recombustion chamber and has a lower end An incinerator having an intermediate partition wall spaced apart from the upper surfaces of the plurality of stokers, a circulation path for circulating a part of the exhaust gas discharged from the incinerator as a circulating exhaust gas, and the intermediate partition wall An injection nozzle that injects the circulating exhaust gas that has passed through the circulation path into the furnace chamber, and a control device that controls the injection nozzle, and the control device is downstream in the transport direction. From the side Inverted from the furnace chamber toward the intermediate partition wall by controlling the injection nozzle so as to inject circulating exhaust gas from the injection nozzle into the furnace chamber toward the flow side, and below the intermediate partition wall A reversal flow of gas is formed through the recombustion chamber.

  According to the above configuration, the combustion exhaust gas flowing in the same direction as the waste and the circulation exhaust gas are efficiently mixed by injecting the circulation exhaust gas from the injection nozzle into the furnace chamber from the downstream side to the upstream side in the transport direction. it can. Further, the circulating exhaust gas is injected into the furnace chamber from an injection nozzle provided at a position corresponding to the intermediate partition wall, reversed from the furnace chamber toward the intermediate partition wall, and passed through the lower part of the intermediate partition wall to the recombustion chamber. By forming the reversal flow of the gas to go to, it is possible to easily reduce the combustion gas temperature uniformly in the furnace chamber and the recombustion chamber. Therefore, it is possible to prevent the combustion temperature of the waste from rising excessively locally in the incinerator and to satisfactorily suppress the generation of nitrogen oxides.

  In addition, since the above-described gas reversal flow is formed, combustion of the combustion gas generated along with the combustion of the waste in the furnace chamber and the recombustion chamber becomes slow, and a flame is generated between the furnace chamber and the recombustion chamber. Because of this flame, the solid unburned matter contained in the waste during combustion is burned by the radiant heat of the combustion gas, etc., and discarded due to the remaining solid unburned matter. Incomplete combustion of objects can be prevented.

In addition, since the circulating exhaust gas having a lower oxygen (O ₂ ) concentration than air or the like is injected into the furnace chamber from the injection nozzle provided at a position corresponding to the intermediate partition wall, the intermediate partition wall from which the circulating exhaust gas is injected In the vicinity, the combustion gas temperature decreases, and the amount of clinker generated by the combustion ash can be reduced.

  The injection nozzle is arranged at a position separated from the furnace wall of the incinerator in a horizontal direction perpendicular to the conveying direction, and obliquely toward the upstream side from the intermediate partition wall. You may arrange | position so that circulating exhaust gas can be injected below.

  According to the above configuration, the injection nozzle injects the circulating exhaust gas from the position separated from the furnace wall inside the incinerator in the horizontal direction perpendicular to the conveyance direction. Compared with the case where it is arranged on the furnace wall (side wall) in a direction perpendicular to the vertical axis, the temperature of the high-temperature gas in the incinerator is reduced in the vicinity of the furnace wall by the circulating exhaust gas injected from the injection nozzle. Therefore, it is possible to prevent clinker from being generated by the combustion ash in the vicinity of the furnace wall and adhering to and growing on the furnace wall.

  In addition, circulating exhaust gas is injected obliquely downward from the intermediate partition wall toward the upstream side in the transport direction, so that the circulating exhaust gas is guided to the furnace wall upstream of the furnace chamber in the transport direction and the ceiling of the furnace chamber. The reverse flow of the gas that reverses toward the partition wall and passes through the lower part of the intermediate partition wall toward the recombustion chamber is easily formed. Therefore, the local temperature rise in an incinerator is suppressed and it can reduce favorably that the combustion temperature of a waste rises excessively.

  The control device may inject the circulating exhaust gas from the injection nozzle into the furnace chamber so that the amount of the circulating exhaust gas in the incinerator becomes a value in the range of 10% to 80% of the theoretical air amount. Alternatively, a supply path for supplying primary air from below the furnace chamber to the furnace chamber is further provided, and the control device is configured such that the amount of circulating exhaust gas in the incinerator is 10% or more of the primary air amount in the incinerator 80 The circulating exhaust gas may be injected from the injection nozzle into the furnace chamber so as to be a value in the range of% or less. Thereby, in an incinerator, waste can be burned in the atmosphere of appropriate oxygen concentration, and it can reduce that the combustion temperature of waste rises excessively.

  A carbon monoxide concentration meter for measuring the carbon monoxide concentration of the exhaust gas is further provided, and when the controller detects that the carbon monoxide concentration of the exhaust gas is 10 ppm or more, Compared to the case where the carbon monoxide concentration meter detects that the carbon oxide concentration is less than 10 ppm, the amount of circulating exhaust gas injected from the injection nozzle into the furnace chamber may be reduced.

  As a result, while appropriately reducing the amount of carbon monoxide emitted from the incineration plant, it is possible to prevent incomplete combustion of the waste due to lack of oxygen or a decrease in the temperature of the combustion gas and appropriately burn the waste. it can.

  An oxygen concentration meter that measures the oxygen concentration in the incinerator is further provided, and the control device detects that the oxygen concentration in the incinerator is 3% or less by the oxygen concentration meter. The amount of circulating exhaust gas injected from the injection nozzle into the furnace chamber may be reduced as compared with the case where the oxygen concentration is detected to be greater than 3%.

  In this way, the control device controls the injection amount of the injection nozzle based on the oxygen concentration in the incinerator, thereby reducing the generation of nitrogen oxides due to excessive increase in the combustion temperature of the waste and oxygen shortage It is possible to prevent incomplete combustion of the waste due to, and to burn the waste well.

  The control device has a gas amount ratio V1 / (V1 + V2) of 0.15 or more and 0.40 or less when the amount of circulating exhaust gas injected into the furnace chamber is V1 and the amount of exhaust gas discharged from the incinerator is V2. Circulating exhaust gas may be injected from the injection nozzle into the furnace chamber so as to have a value in the range.

  In this manner, the control device controls the injection nozzle based on the predetermined gas amount ratio, thereby reducing generation of nitrogen oxides due to excessive increase in the combustion temperature of waste, and Incomplete combustion can be prevented and waste can be burned appropriately.

  A nitrogen oxide concentration meter for measuring the nitrogen oxide concentration of the exhaust gas is further provided, and the control device detects the nitrogen oxide concentration of the exhaust gas when the nitrogen oxide concentration meter detects that the nitrogen oxide concentration of the exhaust gas is 30 ppm or more. Compared with the case where the nitrogen oxide concentration meter detects that the oxide concentration is less than 30 ppm, the injection amount of the circulating exhaust gas from the injection nozzle into the furnace chamber may be increased.

  In this way, the control device controls the injection amount of the injection nozzle based on the nitrogen oxide concentration of the exhaust gas, so that the oxygen concentration in the incinerator is appropriately reduced by the circulating exhaust gas, and the combustion temperature of the waste is excessive. The rise can be suppressed and generation of nitrogen oxides can be reduced, and incomplete combustion of the waste due to lack of oxygen can be prevented, and the waste can be burned appropriately.

  A gas thermometer for measuring a gas temperature at the outlet of the furnace chamber, and the control device detects the gas temperature at the outlet of the furnace chamber to be 900 ° C. or less by the gas thermometer; Compared with the case where the gas thermometer detects that the gas temperature at the outlet of the chamber is higher than 900 ° C., the injection amount of the circulating exhaust gas from the injection nozzle into the furnace chamber may be reduced.

  In this way, the control device controls the injection amount of the injection nozzle based on the gas temperature at the outlet of the furnace chamber, thereby reducing the combustion gas temperature by injecting the circulating exhaust gas while the combustion temperature of the waste is reduced. It is possible to prevent the incomplete combustion of the waste due to the above, and to stably burn the waste.

  A pressure gauge for detecting an internal pressure of the incinerator; and the control device detects that the internal pressure of the incinerator is equal to or higher than a reference value. The amount of circulating exhaust gas injected from the injection nozzle into the furnace chamber may be reduced as compared with the case where the pressure gauge detects that the pressure is less than the pressure gauge.

  In this way, the control device controls the injection amount of the injection nozzle based on the internal pressure of the incinerator, so that the amount of combustion in the incinerator temporarily increases, and the internal pressure of the incinerator rises above the reference value. While reducing the generation of nitrogen oxides due to excessive rise in the combustion temperature of the waste, it is possible to prevent the incomplete combustion of the waste due to a decrease in the combustion gas temperature and to properly burn the waste .

  The plurality of stokers include a dry stoker disposed on the upstream side of the furnace chamber, a combustion stoker disposed on the downstream side of the dry stoker, and a post-combustion stoker disposed on the downstream side of the combustion stoker. And a flame generated by the combustion of the waste may be positioned over the combustion stoker and over the post-combustion stoker.

  According to the above configuration, since the flame generated by the combustion of the waste is positioned over the combustion stoker and the post-combustion stoker, the waste is sufficiently burned while being conveyed. While reducing the generation of oxides, it is possible to prevent incomplete combustion of waste due to lack of oxygen or a decrease in combustion gas temperature.

  According to each aspect of the present invention described above, incomplete incineration of waste in an incineration plant that circulates a part of the exhaust gas from the incinerator as a circulating exhaust gas in the incinerator while favorably suppressing the generation of nitrogen oxides. Combustion can be prevented and the amount of clinker generated can be reduced.

It is a schematic structure figure of an incineration plant concerning an embodiment. It is a schematic diagram which shows the shape of the flame formed in the incinerator of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the “conveying direction” refers to the conveying direction of the waste W in the incinerator 4.

  Drawing 1 is a figure showing the composition of incineration plant 1 concerning an embodiment. FIG. 2 is a schematic diagram showing the shape of a flame formed in the incinerator 4 of FIG. As shown in FIG. 1, the incineration plant 1 includes a hopper 2, a dust feeder 3, an incinerator 4, a boiler 5, a dust collector 6, a chimney 7, a turbine 8, a generator 9, a control device 10, blowers B1 and B2, and a supply A path R1, a discharge path R2, a circulation path R3, and a flow path R4 are provided.

  The hopper 2 is provided on the upstream side in the transport direction of the furnace chamber 11 in the incinerator 4 and communicates with the inside of the incinerator 4. Waste W is charged into the hopper 2. The dust feeder 3 supplies the waste W supplied from the hopper 2 to the incinerator 4 into the furnace chamber 11 in a predetermined conveyance direction.

  The incinerator 4 incinerates the waste W supplied from the outside. The incinerator 4 of the present embodiment is a parallel flow stoker-type incinerator in which the flow direction of the gas generated by the combustion of the waste W and the waste W is parallel, the furnace chamber 11, the recombustion chamber 12, the intermediate chamber 13, and It has a plurality of stokers (dry stoker 15, combustion stoker 16, and post-combustion stoker 17).

  In the furnace chamber 11, the waste W supplied from the hopper 2 is dried by the heat from the burning waste W and burned. The recombustion chamber 12 is disposed downstream of the furnace chamber 11 in the transport direction. The recombustion chamber 12 burns the combustion gas generated by the combustion of the waste W in the furnace chamber 11.

  The intermediate chamber 13 is disposed between the upper side of the furnace chamber 11 and the upper side of the recombustion chamber 12. The intermediate chamber 13 is partitioned from the furnace chamber 11 and the recombustion chamber 12 by an intermediate partition wall 26 extending downward from the upper portion of the incinerator 4.

  The intermediate partition wall 26 divides the upper space of the furnace chamber 11 and the upper space of the recombustion chamber 12, and the lower ends thereof are arranged separately from the upper surfaces of the plurality of stokers 15 to 17. Although the intermediate partition wall 26 of the present embodiment is located above the combustion stoker 16 and on the downstream side in the transport direction from the upstream end of the combustion stoker 16 in the transport direction, the present invention is not limited to this.

  A pipe 27 extending in the horizontal direction perpendicular to the transport direction (direction perpendicular to the paper surface of FIG. 1) is disposed in the intermediate chamber 13. One or a plurality (here, a plurality) of injection nozzles 14 are provided on the peripheral surface of the pipe 27.

  The injection nozzle 14 is provided at a position corresponding to the intermediate partition wall 26. The injection nozzle 14 injects circulating exhaust gas (EGR gas), which is part of the exhaust gas discharged from the incinerator 4, through the discharge path R 2, the circulation path R 3, and the pipe 27 into the furnace chamber 11. As an example, the injection nozzle 14 of this embodiment injects only the circulating exhaust gas, not the mixed gas of the circulating exhaust gas and other gas (air or the like). The injection nozzle 14 is disposed below the highest position on the ceiling of the furnace chamber 11. At a position corresponding to the injection nozzle 14 of the intermediate partition wall 26, an outlet 26 a for exposing the tip of the injection nozzle 14 into the furnace chamber 11 is provided.

  The injection nozzle 14 of this embodiment is arrange | positioned in the position spaced apart inside the incinerator 4 rather than the furnace wall of the incinerator 4 in the horizontal direction perpendicular | vertical to a conveyance direction. The injection direction of the injection nozzle 14 can be set as appropriate.

  The injection nozzle 14 of the present embodiment is disposed so as to be able to inject circulating exhaust gas obliquely downward from the intermediate partition wall 26 toward the upstream side in the transport direction. Thereby, the circulating exhaust gas is injected from the injection nozzle 14 in a direction opposite to the flow direction of the waste W and the combustion gas in the incinerator 4. As an example, the injection nozzle 14 is arranged so as to be able to inject the circulating exhaust gas toward the surface of the waste W on the upstream end portion in the transport direction of the dry stoker 15, thereby causing a gas reverse flow (see FIG. 2) described later. It can be easily formed.

  The temperature of the circulating exhaust gas injected from the injection nozzle 14 is lower than the maximum temperature during combustion of the waste W combusted in the incinerator 4. For example, the temperature of the circulating exhaust gas at the outlet of the boiler 5 can be set to a value in the range of 150 ° C. to 300 ° C., and the combustion temperature of the waste W can be set to a value in the range of 850 ° C. to 1200 ° C. For this reason, the excessive temperature rise of the waste W during combustion is suppressed by injecting the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11. Moreover, the excessive temperature rise of the gas which distribute | circulates the upper space of the stokers 16 and 17 is also suppressed.

  If the temperature of the circulating exhaust gas is too low, the combustion temperature of the waste W may be lowered too much. If the temperature of the circulating exhaust gas is too high, the combustion temperature of the waste W and the space above the stokers 16 and 17 are circulated. Note that the effect of lowering the temperature of the gas is reduced.

  Here, the injection nozzle 14 is provided so as to inject the circulating exhaust gas from directly above either the main combustion region located on the combustion stoker 16 or the rear combustion region located on the rear combustion stoker 17. Is desirable. Thereby, circulating exhaust gas can be effectively injected with respect to the area | region where the temperature rises most in the incinerator 4 in operation. Further, by using the circulating exhaust gas, it is possible to reduce the oxygen concentration in the main combustion region and the post-combustion region, slow down the combustion, and easily extend the combustion time.

  When a plurality of injection nozzles 14 are provided, the interval between adjacent injection nozzles 14 may be uniform or non-uniform. When a plurality of injection nozzles 14 are provided, the injection directions of the injection nozzles 14 as viewed from the conveyance direction or a direction perpendicular to the conveyance direction (hereinafter also simply referred to as a vertical direction) may be parallel or intersect. Also good.

  Further, when the injection directions of the injection nozzles 14 intersect with each other when viewed from the transport direction, the injection directions of the injection nozzles 14 may be directed to the same position on the stalker 16 or 17, or on the stalker 16 or 17. May be directed to a plurality of positions. Further, the injection direction of each injection nozzle 14 may be directed to the inside of the incinerator 4 in a direction perpendicular to the conveyance direction on the waste W.

  When the injection direction of the injection nozzle 14 includes a component in the direction from the downstream side to the upstream side in the transport direction, the injection nozzle 14 reverses from the furnace chamber 11 toward the intermediate partition wall 26 and passes again below the intermediate partition wall 26. A reverse flow of gas toward the combustion chamber 12 is formed.

  Specifically, as shown in FIG. 2, when viewed in the vertical direction, the circulating exhaust gas injected from the injection nozzle 14 rises upward from the lower side of the furnace wall on the upstream side in the conveying direction of the furnace chamber 11, The gas is guided toward the ceiling of the furnace chamber 11 and moves toward the intermediate partition wall 26, and then a gas reversal flow is formed through the lower portion of the intermediate partition wall 26 toward the recombustion chamber 12.

  By forming such a gas reversal flow, the high-temperature gas generated in the main combustion region can be circulated through the drying region located above the drying stoker 15 to increase the temperature above the drying region, and the furnace chamber The space in 11 can be used effectively to make the temperature distribution uniform. Further, it is possible to prevent a local excessive temperature rise in the furnace chamber 11 and the recombustion chamber 12 and reduce the load on the incinerator 4 while suppressing the generation of nitrogen oxides.

  Further, a boiler panel or the like may be installed on the furnace wall (side wall) in a direction perpendicular to the conveying direction of the furnace chamber 11. Thereby, since heat recovery can be efficiently performed from the high-temperature gas flowing in the furnace chamber 11, the operating cost of the incineration plant 1 can be reduced.

  The blowing flow rate at the time of injecting the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 can be set as appropriate. However, if the blowing flow rate is too low (the blowing amount is too small), the effect is small and the blowing flow rate is low. If it is too high (too much blown amount), combustion of the combustion gas may be caused and clinker may adhere to and grow on the intermediate partition wall 26. Therefore, it is desirable to set the flow rate of circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 appropriately, and as an example, it can be set to a value in the range of 20 m / s to 100 m / s.

  Note that not only the circulating exhaust gas but also the oxidizing gas such as air may be injected into the furnace chamber 11 from the injection nozzle 14 together with the circulating exhaust gas. Further, the circulating exhaust gas is not only from the injection nozzle 14 provided in the pipe 27 in the intermediate chamber 13 but also, for example, another injection nozzle provided on the furnace wall (side wall) in the direction perpendicular to the conveying direction of the furnace chamber 11. May be injected into the furnace chamber 11.

  Each stalker 15-17 is arrange | positioned under the furnace chamber 11 and the recombustion chamber 12, and conveys the waste W in a conveyance direction. Each stalker 15-17 has a plurality of grate arranged in the conveying direction. This grate includes a fixed grate provided at a fixed position and a movable grate that reciprocates within a certain range in the transport direction. By this fixed grate and the movable grate, the waste W placed on each of the stalkers 15 to 17 is conveyed in the conveyance direction.

  The dry stoker 15 is disposed below the furnace chamber 11 and upstream in the transport direction. The combustion stoker 16 is disposed below the furnace chamber 11 and downstream of the drying stoker 15 in the transport direction. The tip of the injection nozzle 14 (the air outlet 26a) is located immediately above the combustion stoker 16 of the present embodiment.

  The post-combustion stoker 17 is disposed below the recombustion chamber 12 and downstream of the combustion stoker 16 in the transport direction. The upper surface of the post-combustion stoker 17 is positioned below the upper surface of the combustion stoker 16. A discharge port 28 for discharging the combustion ash of the waste W is disposed on the downstream side in the transport direction from the post-combustion stoker 17 of the incinerator 4.

  Below the incinerator 4, wind boxes 18 to 20 are provided. The air box 18 is disposed below the dry stoker 15. The wind box 19 is disposed below the combustion stoker 16. The wind box 20 is disposed below the post-combustion stoker 17. The wind boxes 18 to 20 are individually connected to the supply path R1.

  The supply path R <b> 1 supplies primary air into the furnace chamber 11 from below the furnace chamber 11. Air is used to burn the waste W. The primary air that has circulated through the supply path R <b> 1 is supplied into the furnace chamber 11 through the wind boxes 18 to 20. The primary air amount supplied from the supply path R1 to the wind boxes 18 to 20 can be individually adjusted for each of the wind boxes 18 to 20. Although not shown in FIG. 1, in this embodiment, secondary air is supplied from the position of the ceiling of the furnace chamber 11 into the furnace chamber 11. The supply position of the secondary air is not limited to this. The primary air amount and the secondary air amount supplied into the furnace chamber 11 are controlled by the control device 10 using an air amount measuring meter.

  The boiler 5 recovers heat from the combustion gas and exhaust gas generated in the incinerator 4. The boiler 5 has a radiation chamber 21, a first flue 22, and a second flue 23. The radiation chamber 21 communicates with the upper portion of the recombustion chamber 12 and extends in the vertical direction, and guides the exhaust gas from below to above.

  Outside the radiation chamber 21, a flow path R4 through which water vapor flows is provided. The flow path R4 extends in the vertical direction. The high-temperature exhaust gas flowing through the radiation chamber 21 is heat-exchanged with the water vapor flowing through the flow passage R4. Thereby, the turbine 8 is rotated by the steam whose temperature has increased. The generator 9 generates power using the rotational driving force of the turbine 8.

  The flue 22, 23 circulates the exhaust gas flowing out from the recombustion chamber 12. The first flue 22 is disposed adjacent to the radiation chamber 21, communicates with the upper portion of the radiation chamber 21, extends in the vertical direction, and guides the exhaust gas from above to below.

  The second flue 23 is disposed adjacent to the first flue 22, communicates with the lower portion of the first flue 22, extends in the vertical direction, and guides the exhaust gas from below to above. A superheater 24 is disposed in the middle of the second flue 23. The superheater 24 recovers heat from the exhaust gas flowing through the second flue 23.

  An upstream end portion of the discharge path R2 is connected to the rear portion of the boiler 5. The downstream end of the discharge path R2 is connected to the chimney 7. The discharge path R <b> 2 guides the exhaust gas discharged from the second flue 23 toward the chimney 7.

  A dust collector 6 and a blower B1 are provided in the middle of the discharge path R2. The dust collector 6 is provided with a bag filter and collects dust from the exhaust gas. The exhaust gas that has passed through the dust collector 6 is attracted by the blower B1, circulates through the chimney 7, and is discharged into the atmosphere.

  The upstream end of the circulation path R3 is connected between the dust collector 6 and the blower B1 in the discharge path R2. The downstream end of the circulation path R3 is connected to the pipe 27. The circulation path R3 circulates a part of the exhaust gas discharged from the incinerator 4 as a circulating exhaust gas. The circulation path R3 of the present embodiment circulates a part of the exhaust gas that has passed through the incinerator 4 and the boiler 5 to the furnace chamber 11 as a circulating exhaust gas.

  A blower B2 is provided in the middle of the circulation path R3. The circulating exhaust gas flowing through the circulation path R3 is attracted by the blower B2 and is injected into the furnace chamber 11 from the injection nozzle 14 provided in the pipe 27.

  The upstream end of the circulation path R3 may be connected to a portion upstream of the dust collector 6 in the discharge path R2 in the flow direction of the exhaust gas, or upstream of the boiler 5 of the incinerator 4 in the flow direction of the exhaust gas. It may be connected to the side part.

  The control device 10 controls the injection nozzle 14. The control device 10 is a computer incorporating a CPU, RAM, and ROM therein, and controls the injection amount of the injection nozzle 14 by adjusting the flow rate of a valve (not shown) provided in the pipe 27 by a predetermined control program. To do. The control device 10 of the present embodiment controls the injection nozzle 14 so as to inject the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 from the downstream side to the upstream side in the transport direction.

  The incineration plant 1 includes an air amount meter 30 for measuring the amount of primary air supplied into the incinerator 4, a carbon monoxide concentration meter 31 for measuring the carbon monoxide concentration of exhaust gas, and nitrogen in the exhaust gas. Nitrogen oxide concentration meter 32 for measuring oxide concentration, gas thermometer 33 for measuring gas temperature at the outlet of furnace chamber 11, and oxygen concentration meter for measuring oxygen concentration in incinerator 4 34 and a pressure gauge 35 for measuring the internal pressure of the incinerator 4 is further provided. These meters 30 to 35 are connected to the control device 10, and each measured value is monitored by the control device 10. The control apparatus 10 of this embodiment performs the specific control shown to the following items (a)-(i) based on a control program.

  (A) From the injection nozzle 14 such that the amount of the exhaust gas circulated becomes a value in the range of 10% to 80% of the theoretical air amount obtained from the incineration amount of the waste and the evaporation amount of the boiler provided in the incineration plant 1. Circulating exhaust gas is injected into the furnace chamber 11.

  (B) Based on the measurement value of the air amount meter 30, the circulating exhaust gas is discharged from the injection nozzle 14 into the furnace chamber 11 so that the circulating exhaust gas amount is in the range of 10% to 80% of the primary air amount. Let spray.

  (C) When the carbon monoxide concentration meter 31 detects that the carbon monoxide concentration of the exhaust gas is 10 ppm or more, and when the carbon monoxide concentration meter 31 detects that the carbon monoxide concentration of the exhaust gas is less than 10 ppm Compared to the above, the injection amount of the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 is reduced.

  (D) When the oxygen concentration meter 34 detects that the oxygen concentration in the incinerator 4 is 3% or less, or when the oxygen concentration meter 34 detects that the oxygen concentration in the incinerator 4 is greater than 3%. In comparison, the amount of circulating exhaust gas injected from the injection nozzle 14 into the furnace chamber 11 is reduced.

  Here, the oxygen concentration meter 34 can be attached to, for example, the outlet of the incinerator 4 or the outlet of the bag filter provided in the dust collector 6. In the example shown in FIG. 1, the oximeter 34 is attached to the outlet of the incinerator 4.

  (E) The gas amount ratio V1 / (V1 + V2) is 0.15 or more and 0.40 or less when the amount of the circulating exhaust gas injected into the furnace chamber 11 is V1 and the amount of the exhaust gas discharged from the incinerator 4 is V2. Circulating exhaust gas is injected from the injection nozzle 14 into the furnace chamber 11 so as to be within the range.

  (F) When the nitrogen oxide concentration meter 32 detects that the nitrogen oxide concentration of the exhaust gas is 30 ppm or more, and when the nitrogen oxide concentration meter 32 detects that the nitrogen oxide concentration of the exhaust gas is less than 30 ppm As compared with the above, the injection amount of the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 is increased.

  (G) When the gas thermometer 33 detects that the gas temperature at the outlet of the furnace chamber 11 is 900 ° C. or less, the gas thermometer 33 detects that the gas temperature at the outlet of the furnace chamber 11 is higher than 900 ° C. Compared to the case, the injection amount of the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 is reduced.

  (H) When the pressure gauge 35 detects that the internal pressure of the incinerator 4 is equal to or higher than the reference value, the injection nozzle is compared with the case where the pressure gauge 35 detects that the internal pressure of the incinerator 4 is less than the reference value. The injection amount of the circulating exhaust gas from 14 into the furnace chamber 11 is reduced.

  (I) In a state where a thermometer capable of measuring the temperature in the incinerator 4 is provided at the outlet of the boiler 5 or above the drying region located on the drying stoker 15 of the furnace chamber 11, the temperature is a predetermined reference When the thermometer detects that the temperature is lower than the temperature, the amount of circulating exhaust gas injected from the injection nozzle 14 into the furnace chamber 11 is smaller than when the thermometer detects that the temperature is equal to or higher than a predetermined reference temperature. Reduce.

  In consideration of the state of the waste W in the incinerator 4 and the like, the control device 10 may perform any one of the controls of the items (a) to (i) alone or combine two or more. You may go. When the control device 10 controls the items (a) to (i), for example, the operator confirms the shape of the flame on the monitor or the like so that the shape of the flame in the incinerator 4 becomes the shape shown in FIG. However, the control device 10 may be adjusted. Further, the degree of “reduction” in the control of the items (c), (d), (g), (h), and (i) can be adjusted as appropriate, and the injection of the circulating exhaust gas from the injection nozzle 14 is complete. Including stoppage.

  When the control device 10 controls the injection nozzle 14 as described above, in the incineration plant 1, as shown in FIG. 2, the furnace chamber 11 is reversed toward the intermediate partition wall 26, and the lower part of the intermediate partition wall 26 is moved below. A reversal flow of gas is formed that passes through the recombustion chamber 12. In addition, the flame generated by the combustion of the waste W is positioned over the furnace chamber 11 and the recombustion chamber 12. The flame may extend upward of the waste W in both the main combustion region on the combustion stoker 16 and the post-combustion region on the post-combustion stoker 17.

  As described above, in the incineration plant 1, the combustion exhaust gas flowing in the same direction as the waste is generated by injecting the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 from the downstream side to the upstream side in the transport direction. The circulating exhaust gas can be mixed efficiently. Further, the circulating exhaust gas is injected into the furnace chamber 11 from the injection nozzle 14 provided at a position corresponding to the intermediate partition wall 26 to form the reverse flow of the gas described above, whereby the inside of the furnace chamber 11 and the recombustion chamber 12 are formed. Inside, the combustion gas temperature can be easily reduced uniformly. Therefore, it is possible to prevent the combustion temperature of the waste W from rising excessively locally in the incinerator 4 and to satisfactorily suppress the generation of nitrogen oxides. In this embodiment, by injecting circulating exhaust gas into the furnace chamber 11 from the injection nozzle 14, the combustion temperature of the combustion gas at the outlet of the furnace chamber 11 is adjusted to 1000 ° C. or less, and generation of nitrogen oxides occurs. Effectively suppressed.

  In addition, since the above-described gas reversal flow is formed, combustion of the combustion gas caused by the combustion of the waste W in the furnace chamber 11 and the recombustion chamber 12 becomes slow, and the flame becomes the furnace chamber. 11 and the inside of the recombustion chamber 12 are positioned lower and lower than before, so that this flame causes unburned matter (particularly, accumulated in the post-combustion region) contained in the waste W during combustion. The unburned waste contained in the waste W) is burned by radiant heat of the combustion gas, etc., and incomplete combustion of the waste W due to the residual solid unburned matter can be prevented.

  Further, since the circulating exhaust gas having a lower oxygen concentration than air or the like is injected into the furnace chamber 11 from the injection nozzle 14 provided at a position corresponding to the intermediate partition wall 26, the intermediate partition wall from which the circulating exhaust gas is injected. In the vicinity of 26, the combustion gas temperature decreases, and the amount of clinker generated by the combustion ash can be reduced.

  Here, when the heat generation amount of the waste W is low, it may take time to dry the waste W, and ignition of the waste W may be delayed. On the other hand, in the present embodiment, high-temperature gas is circulated from the main combustion region to the drying region by injecting the circulating exhaust gas into the furnace chamber 11 from the injection nozzle 14 provided at a position corresponding to the intermediate partition wall 26. The drying effect of the waste W can be improved by raising the temperature of the drying region. As a result, the waste W supplied to the incinerator 4 can be ignited at an early stage, and the waste W is efficiently burned in the main combustion region and the post-combustion region. Incomplete combustion can be prevented.

  Further, in the temperature distribution during operation of the conventional incinerator, the main combustion region is usually the highest temperature and the drying region is relatively low. In the incinerator 4 of the present embodiment, since the temperature of the drying region can be increased as described above, when the boiler water wall pipe is disposed on the furnace wall of the drying region of the incinerator, the amount of absorbed heat is increased and more than the drying region. The heat transfer area of the boiler 5 arranged on the downstream side in the transport direction can be reduced. Thereby, equipment miniaturization of the incineration plant 1 can be achieved, and the heat recovery rate of the incineration plant 1 can be increased.

  Further, in a conventional incinerator during operation, the temperature of the main combustion region may rise excessively and nitrogen oxides may be easily generated. On the other hand, in the incinerator 4 of the present embodiment, the circulating exhaust gas is injected into the furnace chamber 11 from the injection nozzle 14 provided at a position corresponding to the intermediate partition wall 26, so that the excessive temperature in the main combustion region is exceeded. Since the increase is suppressed, generation of nitrogen oxides can be effectively prevented. Moreover, since the temperature rise of the part corresponding to a main combustion area | region is suppressed among the furnace walls (side wall) of a direction perpendicular | vertical to the conveyance direction of the incinerator 4, it can prevent that a clinker adheres to the said furnace wall part. .

  Further, the circulating exhaust gas injected into the furnace chamber 11 from the injection nozzle 14 provided at a position corresponding to the intermediate partition wall 26 rises upward from the lower side of the furnace wall on the upstream side in the conveying direction of the furnace chamber 11. Then, the gas is guided toward the ceiling of the furnace chamber 11 and moves toward the intermediate partition wall 26, and then a reverse flow of gas is formed through the lower portion of the intermediate partition wall 26 toward the recombustion chamber 12 (see FIG. 2) The gas reversal mixing stirring effect in the intermediate partition wall 26 can be enhanced. As a result, the temperature distribution in the furnace chamber 11 is made uniform, and the amount of carbon monoxide is reduced by reducing the air ratio, while incomplete combustion of the waste W due to oxygen deficiency or solid unburnt residue remains. Can be prevented.

  Here, in a conventional incinerator, when circulating exhaust gas is injected into the furnace chamber from the furnace wall of the incinerator around the main combustion region, high-temperature gas around the main combustion region is retained near the furnace wall. A gas flow is formed, and the clinker generated by the combustion ash of the waste W may adhere to and grow on the furnace wall.

  On the other hand, in the incinerator 4 of the present embodiment, the injection nozzle 14 is disposed at a position separated inside the incinerator 4 from the furnace wall of the incinerator 4 in the horizontal direction perpendicular to the conveying direction. The circulating exhaust gas is disposed so as to be able to be injected obliquely downward from the intermediate partition wall 26 toward the upstream side in the conveying direction.

  As a result, the injection nozzle 14 injects the circulating exhaust gas from a position separated inward of the incinerator 4 from the furnace wall in the horizontal direction perpendicular to the transfer direction, so that the injection nozzle 14 is in the transfer direction of the incinerator. Compared with the case where it is arranged on the furnace wall (side wall) in a direction perpendicular to the temperature, the temperature of the high-temperature gas in the incinerator is reduced in the vicinity of the furnace wall by the circulating exhaust gas injected from the injection nozzle 14. Therefore, it is possible to prevent clinker from being generated by the combustion ash in the vicinity of the furnace wall and adhering to and growing on the furnace wall.

  In addition, in the vicinity of the intermediate partition wall 26 by injecting circulating exhaust gas obliquely downward from the intermediate partition wall 26 toward the upstream side in the transport direction at a position separated from the furnace wall of the incinerator 4 to the inside of the incinerator 4. In addition, the temperature decrease of the high-temperature gas as described above is prevented. This prevents the clinker from adhering to and growing on the intermediate partition wall 26.

  Further, the circulating exhaust gas is injected obliquely downward from the intermediate partition wall 26 toward the upstream side in the transport direction, so that the circulating exhaust gas is guided to the furnace wall upstream of the furnace chamber 11 in the transport direction and the ceiling of the furnace chamber 11. Therefore, a reverse flow of the gas that is reversed toward the intermediate partition wall 26 and passes through the lower portion of the intermediate partition wall 26 toward the recombustion chamber 12 is easily formed. Therefore, the local temperature rise in the incinerator 4 is suppressed, and it is possible to satisfactorily reduce the excessive increase in the combustion temperature of the waste W.

  Further, the control device 10 injects the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 so that the circulating exhaust gas amount in the incinerator 4 is in the range of 10% to 80% of the theoretical air amount. Alternatively, the control device 10 may circulate the exhaust gas from the injection nozzle 14 into the furnace chamber 11 so that the amount of the exhaust gas in the incinerator 4 is in the range of 10% to 80% of the primary air amount in the incinerator 4. To spray. Thereby, in the incinerator 4, waste can be burned in an atmosphere with an appropriate oxygen concentration, and the combustion temperature of the waste W can be reduced from excessively rising.

  Moreover, the control apparatus 10 is the amount of injection of the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 when the carbon monoxide concentration of the exhaust gas is 10 ppm or more, compared with the case where the carbon monoxide concentration of the exhaust gas is less than 10 ppm. Therefore, while appropriately reducing the amount of carbon monoxide emitted from the incineration plant 1, the waste W is appropriately prevented by preventing incomplete combustion of the waste W due to insufficient oxygen or a decrease in combustion gas temperature. Can be burned.

  Further, the control device 10 circulates exhaust gas from the injection nozzle 14 into the furnace chamber 11 when the oxygen concentration in the incinerator 4 is 3% or less, compared to when the oxygen concentration in the incinerator 4 is higher than 3%. Reduce the amount of injection.

  In this way, the control device 10 controls the injection amount of the injection nozzle 14 based on the oxygen concentration in the incinerator 4, thereby reducing the generation of nitrogen oxides due to an excessive increase in the combustion temperature of the waste W. At the same time, incomplete combustion of the waste W due to lack of oxygen can be prevented, and the waste W can be burned well.

  Further, since the exhaust gas is injected into the furnace chamber 11 from the injection nozzle 14 so that the gas amount ratio V1 / (V1 + V2) is in the range of 0.15 or more and 0.40 or less, the control device 10 has the gas amount. By controlling the injection nozzle 14 based on the ratio V1 / (V1 + V2), the generation of nitrogen oxides due to an excessive increase in the combustion temperature of the waste W is reduced, and incomplete combustion of the waste W due to lack of oxygen is prevented. Therefore, the waste W can be appropriately burned.

  Further, the control device 10 injects the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 when the nitrogen oxide concentration of the exhaust gas is 30 ppm or more, compared to when the nitrogen oxide concentration of the exhaust gas is less than 30 ppm. Increase the amount.

  In this way, the control device 10 controls the injection amount of the injection nozzle 14 based on the nitrogen oxide concentration of the exhaust gas, thereby appropriately reducing the oxygen concentration in the incinerator 4 with the circulating exhaust gas, and burning the waste W An excessive increase in temperature can be suppressed to reduce generation of nitrogen oxides, and incomplete combustion of the waste W due to lack of oxygen can be prevented, and the waste W can be burned appropriately.

  Moreover, the control apparatus 10 is the case where the gas temperature in the exit of the furnace chamber 11 is 900 degrees C or less, compared with the case where the gas temperature in the exit of the furnace chamber 11 is higher than 900 degreeC, from the injection nozzle 14 in the furnace chamber 11 Reduce the amount of circulating exhaust gas injection.

  In this way, the control device 10 controls the injection amount of the injection nozzle 14 based on the gas temperature at the outlet of the furnace chamber 11, so that the combustion is performed by injecting the circulating exhaust gas while the combustion temperature of the waste W is lowered. By preventing incomplete combustion of the waste W due to a decrease in gas temperature, the waste W can be stably burned.

  In addition, the control device 10, when the internal pressure of the incinerator 4 is equal to or higher than the reference value, injects the circulating exhaust gas from the injection nozzle 14 into the furnace chamber 11 as compared with the case where the internal pressure of the incinerator 4 is less than the reference value. Reduce.

  As described above, the control device 10 controls the injection amount of the injection nozzle 14 based on the internal pressure of the incinerator 4, so that the combustion amount in the incinerator 4 temporarily increases, and the internal pressure of the incinerator 4 is the reference value. The combustion temperature of the waste W is excessively increased and the generation of nitrogen oxides is reduced, and incomplete combustion of the waste W due to a decrease in the combustion gas temperature is prevented, thereby reducing the waste W. Can be properly burned.

  Further, since the flame generated by the combustion of the waste W is positioned over the combustion stoker 16 and the upper combustion stoker 17, the waste W is sufficiently burned while being conveyed. Incomplete combustion of the waste W due to lack of oxygen or a decrease in the temperature of the combustion gas can be prevented while reducing nitrogen oxides generated by the combustion of NO.

  The present invention is not limited to the above-described embodiment, and the configuration and method of the present invention can be changed, added, or deleted without departing from the spirit of the present invention.

R1 supply channel R3 circuit W waste 1 incineration plant 4 incinerator 10 control device 11 furnace chamber 12 recombustion chamber 14 injection nozzle 15 dry stoker (stoker)
16 Combustion stoker (stoker)
17 Post Combustion Stoker (Stoker)
26 Middle partition wall

Claims (11)

A furnace chamber for burning waste, a recombustion chamber for burning combustion gas generated by combustion of waste in the furnace chamber, and disposed below and in advance of the furnace chamber and the recombustion chamber A plurality of stokers for transporting waste in the transport direction; an intermediate partition wall that partitions the upper space of the furnace chamber and the upper space of the recombustion chamber and has a lower end spaced apart from the upper surfaces of the plurality of stokers; An incinerator having,
A circulation path for circulating a part of the exhaust gas discharged from the incinerator as a circulating exhaust gas;
An injection nozzle that is provided at a position corresponding to the intermediate partition wall and injects the circulating exhaust gas that has passed through the circulation path into the furnace chamber;
A control device for controlling the spray nozzle,
The control device controls the injection nozzle so as to inject the circulating exhaust gas from the injection nozzle into the furnace chamber from the downstream side to the upstream side in the transport direction, so that the intermediate partition wall from the furnace chamber An incineration plant in which a reverse flow of gas is formed that is reversed toward the re-combustion chamber through the lower part of the intermediate partition wall.   The injection nozzle is arranged at a position separated from the furnace wall of the incinerator in a horizontal direction perpendicular to the conveying direction, and obliquely toward the upstream side from the intermediate partition wall. The incineration plant of Claim 1 arrange | positioned so that circulating exhaust gas can be injected below.   The said control apparatus injects circulating exhaust gas from the said injection nozzle in the said furnace chamber so that the amount of circulating exhaust gas in the said incinerator may become the value of the range of 10% or more and 80% or less of theoretical air quantity. Or the incineration plant of 2. A supply path for supplying primary air from below the furnace chamber to the furnace chamber;
The control device injects the circulating exhaust gas from the injection nozzle into the furnace chamber so that the amount of the circulating exhaust gas in the incinerator becomes a value in the range of 10% to 80% of the primary air amount in the incinerator. The incineration plant according to any one of claims 1 to 3. A carbon monoxide concentration meter for measuring the carbon monoxide concentration of the exhaust gas;
When the carbon monoxide concentration meter detects that the carbon monoxide concentration of the exhaust gas is 10 ppm or more, the controller detects that the carbon monoxide concentration of the exhaust gas is less than 10 ppm by the carbon monoxide concentration meter. The incineration plant of any one of Claims 1-4 which reduces the injection amount of the circulation waste gas from the said injection nozzle into the said furnace chamber compared with the case where it did. An oxygen concentration meter for measuring the oxygen concentration in the incinerator;
When the oxygen concentration meter detects that the oxygen concentration in the incinerator is 3% or less, the controller detects that the oxygen concentration in the incinerator is higher than 3% by the oxygen concentration meter. The incineration plant of any one of Claims 1-5 which reduces the injection amount of the circulation waste gas from the said injection nozzle into the said furnace chamber compared with the case.   The control device has a gas amount ratio V1 / (V1 + V2) of 0.15 or more and 0.40 or less when the amount of circulating exhaust gas injected into the furnace chamber is V1 and the amount of exhaust gas discharged from the incinerator is V2. The incineration plant according to any one of claims 1 to 6, wherein circulating exhaust gas is injected from the injection nozzle into the furnace chamber so as to be a value in a range of. A nitrogen oxide concentration meter for measuring the nitrogen oxide concentration of the exhaust gas;
When the nitrogen oxide concentration meter detects that the nitrogen oxide concentration of the exhaust gas is 30 ppm or more, the control device detects that the nitrogen oxide concentration of the exhaust gas is less than 30 ppm by the nitrogen oxide concentration meter. The incineration plant of any one of Claims 1-7 which increases the injection amount of the circulation waste gas from the said injection nozzle into the said furnace chamber compared with the case where it did. A gas thermometer for measuring the gas temperature at the furnace chamber outlet;
When the gas thermometer detects that the gas temperature at the outlet of the furnace chamber is 900 ° C. or less, the control device indicates that the gas temperature at the outlet of the furnace chamber is higher than 900 ° C. The incineration plant of any one of Claims 1-8 which reduces the injection amount of the circulating exhaust gas from the said injection nozzle into the said furnace chamber compared with the case where it detects by. A pressure gauge for detecting the internal pressure of the incinerator;
When the control device detects that the internal pressure of the incinerator is equal to or higher than a reference value by the pressure gauge, compared to the case where the internal pressure of the incinerator is detected to be less than the reference value by the pressure gauge. The incineration plant according to any one of claims 1 to 9, wherein an injection amount of the circulating exhaust gas from the injection nozzle into the furnace chamber is reduced. The plurality of stokers include a dry stoker disposed on the upstream side of the furnace chamber, a combustion stoker disposed on the downstream side of the dry stoker, and a post-combustion stoker disposed on the downstream side of the combustion stoker. Including
The incineration plant according to any one of claims 1 to 10, wherein a flame generated by combustion of waste is located above the combustion stoker and above the post-combustion stoker.

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