JP2006162109A - Waste incinerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste incinerator capable of excellently removing dust sticking to an inner surface of a gas nozzle, without using steam as a removing medium, in the waste incinerator for extracting and blowing a part of furnace inside gas or exhaust gas into the furnace inside gas in a furnace via the gas nozzle. <P>SOLUTION: The dust stuck in the gas nozzle 21 is removed by using a jetting nozzle 25 having a Laval nozzle part capable of jetting supplied pressurized air as nozzle jetting gas of a supersonic speed causing a shock wave, and a suction guiding part 32 for imparting a straightly advancing property to its nozzle jetting gas by sucking surrounding air from a suction hole. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a waste incinerator for incinerating waste such as municipal waste, and more particularly, to a waste incinerator for extracting a part of the furnace gas or exhaust gas and blowing it into the furnace. is there.

  Conventionally, proven stoker-type incinerators are frequently used as waste incinerators installed in waste treatment facilities.

  Further, a gas nozzle for extracting gas by extracting a part of the in-furnace gas above the post-burner stoker and ash discharge port of the stoker type incinerator or a part of the exhaust gas flowing downstream of the incinerator. The in-furnace gas in the incinerator is agitated and mixed, and oxygen in the blown-in furnace gas or exhaust gas is used for combustion to burn nitrogen oxides and the amount of exhaust gas. There is also a known technique for reducing the amount.

  However, according to this type of conventional technology, as the in-furnace gas or exhaust gas continues to be blown into the furnace, the dust contained in the in-furnace gas or exhaust gas adheres to and accumulates on the inner wall surface of the gas nozzle, There was a problem that the gas nozzle was blocked.

  Therefore, in Patent Document 1, a vapor nozzle for vapor injection is provided in the gas nozzle, and high pressure steam of 1.0 to 1.5 MPa is injected from the vapor nozzle into the gas nozzle, thereby adhering to the inner wall surface of the gas nozzle. Waste incinerators have been proposed that remove the generated dust and prevent clogging of the gas nozzles.

JP 2003-314814 A

  However, in the waste incinerator described in Patent Document 1, since steam is used as a nozzle removal medium, when dust removal is insufficient, moisture is contained in the dust remaining on the inner wall surface of the gas nozzle, As a result, there is a problem in that the residual dust is changed to one that is extremely difficult to remove. Further, since steam is blown into the incinerator, there is a problem that the combustion state may fluctuate greatly in the incinerator.

  The present invention has been made in order to solve such problems. In a refuse incinerator having a gas nozzle for blowing the extracted in-furnace gas or exhaust gas into the furnace, the present invention adheres to the inner wall surface of the gas nozzle. An object of the present invention is to provide a waste incinerator capable of satisfactorily removing removed dust.

In order to achieve the above object, a waste incinerator according to the first invention comprises:
In a waste incinerator equipped with a gas nozzle that extracts a portion of the furnace gas or exhaust gas and blows it into the furnace,
A deposit removing means for removing deposits attached to the inner wall surface of the gas nozzle;
The deposit removing means includes a nozzle for injecting a compressible fluid such as air into the gas nozzle. The nozzle is provided with a cylindrical fluid guide at the tip of a Laval nozzle, and the fluid guide is provided with the nozzle. The present invention is characterized in that an elongated opening is formed in the flow direction of the compressive fluid.

Next, the waste incinerator according to the second invention is:
In a waste incinerator equipped with a gas nozzle that extracts a portion of the furnace gas or exhaust gas and blows it into the furnace,
A deposit removing means for removing deposits attached to the inner wall surface of the gas nozzle;
The deposit removing means includes a shock wave generating electrode that generates a shock wave toward the gas nozzle when supplied with a pulse voltage.

  In the first invention or the second invention, the pressure detecting means for detecting the blowing pressure of the in-furnace gas or exhaust gas blown into the furnace through the gas nozzle, and the pressure detecting means increases the blowing pressure to a set value or more. When this is detected, the deposit removing means is activated, and when the blowing pressure is less than a predetermined value, the deposit removing means is controlled so that the deposit removing means is inactivated. Is preferably provided (third invention). The deposit removing means may be periodically operated by a timer (fourth invention).

  According to the first aspect of the present invention, the deposit removing means includes a nozzle having a Laval nozzle portion and a fluid guide portion, and an elongated opening formed in the fluid guide portion in the flow direction of the compressive fluid. Therefore, a supersonic fluid (compressive fluid such as air) with a straight shock wave can be injected into the gas nozzle for blowing the gas or exhaust gas into the furnace. The deposits adhered to the inner wall surface of the gas nozzle can be reliably removed, and the gas nozzle can be prevented from being blocked. Therefore, unlike the conventional one, it is not necessary to use a large amount of water vapor as a deposit removal medium, so that the deposit on the inner wall surface of the gas nozzle does not change to one that contains moisture and is difficult to remove.

  In addition, since the deposits can be removed efficiently, the injection amount of the compressive fluid at the time of deposit removal is small, so fluctuations in the combustion state in the furnace can be suppressed, and the exhaust gas treatment equipment on the downstream side It is possible to reduce the burden on the air inducer and to reduce the size of the fluid generation source.

  According to the second aspect, deposits on the inner wall surface of the gas nozzle can be reliably removed by a shock wave generated by electrical energy. In addition, since shock waves generated by electrical energy serve as a deposit removal medium, fluids such as air are not injected for the purpose of removing deposits. It is possible to prevent the occurrence of fluctuations in the combustion state.

  If the configuration of the third invention is adopted, the operation of the deposit removing means is controlled based on the judgment pressure of the gas or exhaust gas blown into the furnace, so the operation of the deposit removing means is the minimum necessary. It is possible to reduce the running cost for removing the deposits.

  Moreover, even when the configuration of the fourth invention is adopted, it is possible to reduce the running cost by suppressing the number of operations of the deposit removing means.

  Next, specific embodiments of the waste incinerator according to the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a schematic configuration diagram of a waste incineration facility according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a blowing device, and FIG. 3 is a cross-sectional view (a) and a diagram of a nozzle. XX sectional views of 3 (a) are shown.

  In this embodiment, the waste treatment facility 1 is provided with a stoker-type incinerator (garbage incinerator; hereinafter simply referred to as “incinerator”) 2 for incinerating waste. 2, in order to rapidly cool the exhaust gas after heat exchange to a required temperature, and heat exchange equipment such as a boiler 3 and an economizer 4 that perform heat exchange treatment of the exhaust gas discharged from the incinerator 2. The temperature reducing tower 5, the dust collector 6 for collecting the exhaust gas after the temperature reduction treatment, and the air attracting device 8 for discharging the exhaust gas after the dust collection from the chimney 7 are provided in order from the upstream side.

  The incinerator 2 is provided with a hopper 11 for storing waste, and a waste supply device 12 is provided below the hopper 11. A stepped stoker 13 including a dry stoker 13a, a combustion stoker 13b, and a post-combustion stage stoker 13c is provided downstream of the waste supply device 12 and below the incinerator 2, and the post-combustion stage stoker 13c On the downstream side, an ash discharge port 14 for discharging the incinerated ash on the post-combustion stage stoker 13c is provided.

  Further, a primary combustion region (indicated by symbol A in FIG. 1) is formed in the upper region of the stoker 13, and the furnace wall further above the primary combustion region A is placed in the furnace. A secondary combustion air supply port 15 is provided for forming a secondary combustion region (indicated by symbol B in FIG. 1) for completely burning the in-furnace gas after the primary combustion with the supplied secondary combustion air. It has been.

  Here, in the present embodiment, a part of the in-furnace gas containing a large amount of oxygen above the after-burning stage stoker 13c and the ash outlet 14 in the incinerator 2 is extracted and subjected to necessary processing such as heat exchange processing. After that, a method is adopted in which the in-furnace gas is blown back into the incinerator 2 from a plurality of blowing devices 16 provided below the secondary combustion air supply port 15 (in FIGS. 1 and 2). Only one blowing device 16 is shown in the figure). In the following description, in order to avoid confusion with the in-furnace gas in the incinerator 2, the in-furnace gas partially extracted from the incinerator 2 and blown into the furnace through the blowing device 16 is “refluxed”. It will be referred to as “gas”.

  As shown in FIG. 2, the blowing device 16 is arranged so as to be orthogonal to the furnace wall of the incinerator 2, and the distal end portion is opened in the incinerator 2 and connected to the wall portion near the base end portion. A gas nozzle 21 is provided that blows and recirculates the in-furnace gas supplied through the supply pipe 20 into the incinerator 2 as a reflux gas from the opening of the tip. The gas nozzle 21 has a pressure detector 22 that detects the pressure of the recirculated gas blown into the incinerator 2 from the gas nozzle 21, and removes deposits adhering to the inner wall surface of the gas nozzle 21 as the recirculated gas is blown. A dust removing unit (attached matter removing means) 23 is provided.

  The dust removing unit 23 includes a pressurized air supply source (not shown), an air tank 24 for storing the pressurized air supplied from the pressurized air supply source, and a central portion of the body portion of the gas nozzle 21. An injection nozzle (nozzle) that is fixed to the end wall surface and is disposed along the axial direction of the gas nozzle 21 such that the tip end thereof (specifically, a fluid guide portion 32 described later) is positioned in the gas nozzle 21. 25, the pressurized air supply pipe 26 with an electromagnetic valve 26 'that connects the air tank 24 and the injection nozzle 25 and supplies the compressed air (compressible fluid) stored in the air tank 24 to the injection nozzle 25. It is configured with. In addition to air, compressive fluids such as nitrogen and clean gas after exhaust gas treatment can be used as the jet fluid from the jet nozzle 25.

  As shown in FIG. 3A, the injection nozzle 25 has a cylindrical outer tube 30 and a Laval nozzle portion 31 that is mounted on the inner end side of the outer tube 30. The Laval nozzle portion 31 has a distal end portion that is slightly smaller in diameter than the inner diameter of the outer tube 30, and a proximal end portion that is substantially the same diameter as the inner diameter of the outer tube 30. The Laval nozzle portion 31 is inserted from the base end side of the outer tube 30 and is welded to the outer tube 30 at the base end portion, thereby being supported by the outer tube 30. Note that one end of the pressurized air supply pipe 26 is fixed to the base end portion of the injection nozzle 25 (illustration is omitted in FIG. 3A), and at the base end portion of the Laval nozzle portion 31, Pressurized air from the air tank 24 can be supplied.

  Here, the Laval nozzle refers to a medium-thinned nozzle whose middle part is squeezed into a throat. According to such a Laval nozzle, when the air pressure on the base end side is made higher than the air pressure on the tip end side, and the fluid velocity at the throat becomes the sonic velocity, air accompanied by a supersonic shock wave from the tip portion. It is known to be jetted.

  In the present embodiment, the velocity of the air at the throat S of the Laval nozzle portion 31 becomes the sonic velocity, that is, the supersonic nozzle injection gas (the additive gas after being injected from the Laval nozzle portion 31 from the tip portion of the Laval nozzle portion 31). Compressed air (indicated by reference symbol “a” in FIG. 3A), the diameter of the throat S, the distance from the base end portion of the Laval nozzle portion 31 to the throat S, and the tip portion of the Laval nozzle portion 31 from the throat S , The diameter of the opening of the proximal end and the opening of the distal end of the Laval nozzle portion 31, the air pressure of the pressurized air supplied to the proximal end of the Laval nozzle portion 31, and the like are appropriately adjusted.

  A fluid guide portion 32 is provided at the front end portion of the Laval nozzle portion 31 at the distal end portion of the outer tube 30. In the fluid guide portion 32, a plurality of elongated suction holes (openings) 33 are formed at an equal pitch in the circumferential direction of the outer tube 30 in the axial direction of the injection nozzle 25. When the nozzle injection gas a is injected from the Laval nozzle portion 31, these suction holes 33 suck air from the side of the injection nozzle 30 and surround the nozzle injection gas a (FIG. 3 ( a) (indicated by a middle symbol b) is formed, and the nozzle injection gas a is prevented from diffusing and imparts straightness to the nozzle injection gas a.

  The pressure detector 22 is electrically connected to an electromagnetic valve 26 ′ of a pressurized air supply pipe 26, and opens and closes the electromagnetic valve 26 ′ based on the blowing pressure of the reflux gas acquired as detection data. It has a function to perform control.

  In the present embodiment configured as described above, the reflux gas extracted from the upper region of the afterburner stage stoker 13c and the ash discharge port 14 of the incinerator 2 and subjected to necessary processing such as heat exchange processing is supplied to the supply pipe. After being supplied to the gas nozzle 21 via 20, the gas nozzle 21 is blown into the in-furnace gas in the incinerator 2 from the opening of the tip of the gas nozzle 21. As a result, the in-furnace gas in the incinerator 2 is agitated and mixed, and the residual oxygen in the blown-in reflux gas is used for combustion in the incinerator 2 to suppress nitrogen oxides (NOx) and the amount of exhaust gas. Reduction and the like.

  If the recirculation gas is continuously blown as described above, dust contained in the recirculation gas adheres and accumulates on the inner surface of the gas nozzle 21, which may hinder the flow of the recirculation gas. Therefore, dust adhering to the inner wall surface of the gas nozzle 21 is removed as follows.

  As dust in the reflux gas adheres and accumulates on the inner wall surface of the gas nozzle 21 and the thickness of the dust increases, the flow path of the reflux gas becomes narrower, and the blowing pressure of the reflux gas inevitably increases. When the pressure detector 22 detects the recirculation gas blowing pressure of a predetermined value or more, the control means (not shown) determines that “the dust on the inner wall surface of the gas nozzle 21 needs to be removed”, and the electromagnetic The valve 26 ′ is automatically opened, and pressurized air is supplied to the injection nozzle 25. Then, a supersonic nozzle injection gas a excellent in straightness accompanied by a shock wave is injected into the gas nozzle 21 from the tip of the injection nozzle 25, and dust adhered to the gas nozzle due to the combined action of the nozzle injection gas a and the shock wave. Blowed away.

  When dust in the gas nozzle 21 is removed by the injection of the nozzle injection gas a, the flow path of the recirculation gas widens, and as a result, the recirculation gas blowing pressure detected by the pressure detector 22 decreases. . When the blowing pressure drops below a predetermined value, the control means determines that “the dust on the inner wall surface of the gas dust does not need to be removed”, and the electromagnetic valve 26 ′ is automatically closed. Thereby, the injection of the nozzle injection gas a is stopped.

  In the present embodiment, since the supersonic nozzle injection gas a excellent in linearity with a shock wave is injected from the injection nozzle 25 having the Laval nozzle portion 31 and the fluid guide portion 32 into the gas nozzle 21, Dust adhering to the inner wall surface can be reliably removed. Therefore, there is no need to use water vapor as a dust removal medium unlike conventional ones, and there is no problem that the dust that has not been removed contains moisture and changes extremely difficult to remove.

  Further, since the supersonic nozzle injection gas a excellent in straightness with a shock wave is used as a dust removal medium, the dust removal efficiency is good, so the injection amount of the nozzle injection gas a is small, and the injection It takes less time. Therefore, it is possible to prevent the combustion state in the incinerator 2 from fluctuating due to the injection of the nozzle injection gas a, and to reduce the size of the source of pressurized air (air tank 24, pressurized air supply source, etc.). The burden on the air attracting machine 8 can be reduced, and the running cost for dust removal can be reduced.

  In addition, since the configuration in which the nozzle injection gas a for dust removal is injected only when the recirculation gas blowing pressure detected by the pressure detection means 22 exceeds a predetermined value is employed, Thus, it is possible to omit the injection of the nozzle injection gas a, and it is possible to further reduce the running cost.

  Next, in order to confirm the performance of the dust removing unit 23 of the present embodiment, the dust removing unit to which a normal nozzle having neither the Laval nozzle 31 nor the fluid guide unit 32 is attached and the dust removing unit 23 of the present embodiment are provided. The dust removal operation of the gas nozzle 21 is performed for a predetermined period for each dust removing unit, the number of times of nozzle injection gas injection per day, the time of nozzle injection gas injection per day, and the amount of nozzle injection gas injection per time In addition, the injection amount of the nozzle injection gas per day was examined, and the results are summarized in Table 1.

  As is clear from Table 1, the dust removal unit 23 of the present embodiment using the injection nozzle 25 having the Laval nozzle unit 31 and the fluid guide unit 32 also has a nozzle injection gas injection amount per dust removal operation. Also, it was confirmed that the injection amount of the injection gas per day can be significantly reduced as compared with the case of using a normal nozzle.

  In the present embodiment, a method has been adopted in which a part of the furnace gas above the post-combustion stage stoker 13 c and the ash outlet 14 is extracted and refluxed and blown into the furnace from the gas nozzle 21. It is also possible to adopt a method in which a part of the exhaust gas flowing on the downstream side is extracted and refluxed, and this exhaust gas is blown into the furnace from the gas nozzle 21.

  Further, in the present embodiment, a configuration is adopted in which the injection of the nozzle injection gas a is controlled in the gas nozzle 21 based on the recirculation gas injection pressure. However, the nozzle injection gas is set at regular time intervals set by a timer. a may be injected into the gas nozzle 21. In such a case, the deposits in the gas nozzle 21 can be reliably removed while suppressing the number of injections of the nozzle injection gas a.

  In the present embodiment, the pressure detector 22, the electromagnetic valve 16 'inserted in the pressurized air supply pipe 16, and the like correspond to the control means.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to the drawings.

  FIG. 4 shows a schematic configuration diagram (upper half) of a probe according to the second embodiment and a circuit diagram (lower half) of a pulse voltage supply unit. In this embodiment, the configuration is basically the same as that of the first embodiment except that a probe and a pulse voltage supply unit are used instead of the dust removing unit 23 of the first embodiment. Only the probe and the pulse voltage supply unit will be described, and the description of other parts will be omitted.

  In this embodiment, a probe (shock wave generating electrode) 40 for generating a shock wave from the tip is fixed to the base end wall surface of the gas nozzle 21, and the probe 40 is connected to the outside of the gas nozzle 21. A pulse voltage supply unit 41 for supplying a pulse voltage is provided.

  As shown in FIG. 4, the pulse voltage supply unit 41 is arranged in parallel with an AC power source 42, a voltage-adjusting slidac 43, a transformer 44, a rectifier 45, a charging resistor 46, and a resistor 47. The amplitude and frequency of the pulse voltage output to the probe 40 are mainly adjusted by adjusting the resistance value of the resistor 47 and the electric capacity of the capacitors 48A and 48B. Can be adjusted appropriately. In FIG. 4, reference numeral 49 is a voltmeter, and reference numeral 50 is an ammeter.

  The probe 40 has an inner conductor (conductive wire) 55 arranged in the axial direction of the probe 40 and a cylindrical outer conductor 56 arranged on the outer periphery of the inner conductor 55 at a predetermined interval at the central shaft portion thereof. The insulator 57 is interposed between the inner conductor 55 and the outer conductor 56 except for the tip of the probe 40. Here, the inner conductor 55 and the outer conductor 56 are respectively connected to the pulse voltage supply unit 41.

  According to the probe 40 configured in this way, by receiving the supply of the pulse voltage from the pulse voltage supply unit 41, the distal end portion 55 ′ of the inner conductor 55 without the insulator 57 interposed therebetween, and the distal end of the outer conductor 56 A discharge is generated between the portion 56 ′ and a shock wave SW is generated in the gas nozzle 21 by this discharge. The dust adhering to the gas nozzle 21 is given an impact by the shock wave SW, and is removed from the inner wall surface of the gas nozzle 21 and removed.

  According to the present embodiment, the dust adhering to the inner wall surface of the gas nozzle 21 is removed by the shock wave SW generated by the electric energy, so that water vapor is not used as a dust removal medium unlike the conventional one. . Therefore, unlike the conventional case, there is no problem that the dust that has not been removed contains moisture and changes to one that is extremely difficult to remove. Further, since air or other gas fluid is not supplied into the incinerator 2 as a dust removal medium, the combustion state in the incinerator 2 does not fluctuate and is installed downstream of the incinerator 2. The burden on the air attracting machine 8 and the like does not increase.

  In the second embodiment, as in the first embodiment, a method of blowing the in-furnace gas into the incinerator 2 or a method of blowing the exhaust gas into the incinerator 2 may be adopted. In addition, a control means is provided so that a pulse voltage is supplied to the probe 40 and a shock wave SW is generated only when the recirculation gas (in-furnace gas, exhaust gas) blowing pressure increases beyond a required value. In other words, a method of generating the shock wave SW can be adopted.

1 is an overall schematic configuration diagram of a waste treatment facility according to a first embodiment of the present invention. Schematic configuration diagram of blowing device XX sectional view of the nozzle cross-sectional view (a) and FIG. 3 (a) The schematic block diagram (upper half part) of the probe which concerns on 2nd Embodiment of this invention, and the circuit diagram of a pulse voltage supply part (lower half part)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Waste disposal equipment 2 Stoker type incinerator 16 Blowing device 21 Gas nozzle 22 Pressure detector 23 Dust removal part 25 Injection nozzle 26 Solenoid valve 31 Laval nozzle part 32 Fluid guide part 33 Suction hole 40 Probe 41 Pulse voltage supply part

Claims (4)

In a waste incinerator equipped with a gas nozzle that extracts a portion of the furnace gas or exhaust gas and blows it into the furnace,
A deposit removing means for removing deposits attached to the inner wall surface of the gas nozzle;
The deposit removing means includes a nozzle for injecting a compressible fluid such as air into the gas nozzle. The nozzle is provided with a cylindrical fluid guide at the tip of a Laval nozzle, and the fluid guide is provided with the nozzle. A refuse incinerator having a configuration in which an elongated opening is formed in a flow direction of a compressive fluid. In a waste incinerator equipped with a gas nozzle that extracts a portion of the furnace gas or exhaust gas and blows it into the furnace,
A deposit removing means for removing deposits attached to the inner wall surface of the gas nozzle;
A garbage incinerator characterized in that the deposit removing means includes a shock wave generating electrode for generating a shock wave toward the gas nozzle when supplied with a pulse voltage.   A pressure detecting means for detecting a blowing pressure of furnace gas or exhaust gas blown into the furnace through the gas nozzle, and when the pressure detecting means detects that the blowing pressure has increased to a set value or more, the deposit 3. A control means is provided for controlling the deposit removing means so that the deposit removing means is in an activated state and when the blowing pressure is less than a predetermined value, the deposit removing means is inactivated. Garbage incinerator.   The refuse incinerator according to claim 1 or 2, wherein the deposit removing means is periodically operated by a timer.

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