JP5783078B2 - Waste gasification melting furnace clinker destruction and suppression device - Google Patents

Description

The present invention relates to a clinker destruction / occurrence suppression device for a vertical waste gasification melting furnace that thermally decomposes and gasifies waste and melts the thermal decomposition residue.

  As a technology for treating waste such as municipal waste and shredder dust, gasification melting processing is known in which waste is pyrolyzed and gasified to generate flammable gas, and the pyrolysis residue is melted and discharged as slag. Yes.

  In this treatment method, the heat of combustion can be recovered by pyrolyzing and gasifying the waste, and after the residue is melted and discharged as slag, the amount to be finally disposed of in landfill disposal etc. It has the advantage that the volume can be reduced. There are several types of melting furnaces for performing such treatment, and one of them is a shaft type waste gasification melting furnace having a vertical shape.

  This shaft-type waste gasification and melting furnace, for example, combusts coke deposited on the bottom of the furnace, throws the waste on this high-temperature coke, pyrolyzes and partially oxidizes it, gasifies it, and generates residues. It is a furnace of a system that performs a process of melting into slag (see Patent Document 1).

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

  In such a melting furnace, oxygen-containing gas is blown into the furnace in each of the three regions. In order to blow this oxygen-containing gas, the main tuyere is provided in the high-temperature combustion zone, and the coke in the coke bed deposited and burned is burned to melt the pyrolysis residue of the waste Of oxygen-enriched air. In addition, the waste layer is provided with a sub tuyere, and the waste deposited and flowed gently, and air is blown in to thermally decompose and partially oxidize the waste. In addition, the freeboard section is provided with a third stage tuyere, for partially burning part of the pyrolysis gas (combustible gas) generated by pyrolyzing waste and maintaining the inside at a predetermined temperature Air is blown.

  As described above, the shaft-type waste gasification and melting furnace is a facility capable of performing both pyrolysis gasification treatment and melting treatment in a single furnace as the waste falls in the furnace. The input waste is pyrolyzed and separated into gas and residue. Waste from the main and sub tuyere is pyrolyzed, and the gas generated in the furnace due to this pyrolysis rises in the waste layer from the bottom of the furnace or around the coke bed, passes through the free board, and passes through the furnace. It is discharged to the secondary combustion chamber outside the furnace from the exhaust flue provided in the upper part. The gas contains a large amount of combustible gas and is combusted in the secondary combustion chamber, and heat is recovered by the boiler to generate steam, which is used for power generation and the like. The gas discharged from the boiler is treated with exhaust gas such as relatively coarse dust is removed with a cyclone, further cooled with a temperature reducing device, harmful gas is removed by reaction with a hazardous substance remover, and dust is removed with a dust collector. After that, it is dissipated from the chimney to the atmosphere. Further, the pyrolysis residue moves downward in the furnace, is melted in a high-temperature combustion zone at the lower part of the furnace, and is discharged as slag and metal.

  In such a melting furnace, air is blown from the sub tuyere to the waste layer formed on the high-temperature combustion zone having the coke bed so that the thermal decomposition and gasification of the waste can be stably performed. In operation, the amount of waste that is thermally decomposed per unit time is maintained at a predetermined value by adjusting the amount of air blown from the sub tuyere, etc., and the waste layer height is stabilized within a predetermined range. Stabilization is performed by suppressing fluctuations in the amount of gas. At that time, the temperature in the furnace around the auxiliary tuyere installation part is set to a range of approximately 650 ° C to 900 ° C.

  However, in actual operation, if there is a change in the properties of the waste introduced from the upper part of the furnace or a fluctuation in the supply amount, the height of the waste layer temporarily becomes higher than the predetermined range, and the position of the sub tuyere However, the upper waste layer thickness may increase. In such a state, the periphery of the tip of the sub tuyere may be locally heated (overheated), and the formation of a high temperature region by this local heating melts waste and dust, and the furnace near the sub tuyere It adheres to the inner wall surface in a lump. This massive deposit is called clinker. On the inner wall surface of the furnace, the clinker adheres from the vicinity of the sub tuyere arranged at approximately equal intervals in the furnace circumferential direction, and gradually deposits are formed in a ring shape over the entire circumference in the furnace circumferential direction. The clinker adhering to the inner wall surface of the furnace hinders stable lowering of the waste thrown in from the upper portion, or causes a phenomenon in which waste and dust are accumulated and remain on the clinker.

  If the clinker adhering to the inner wall of the furnace falls off and collapses, and the waste that remains on the clinker falls at once, the amount of waste combustion increases rapidly and the amount of gas generated from the furnace varies greatly. Will be allowed to. This fluctuation in the amount of generated gas causes a fluctuation in the internal pressure of the furnace, causing a problem in the stable operation of the gasification melting furnace. In addition, when combustible gas in the generated gas is burned in the secondary combustion chamber, it is possible to adjust the amount of combustion air blown supplied to the secondary combustion chamber by following the sudden fluctuation in the amount of generated gas. First, it causes problems such as an increase in the amount of carbon monoxide gas due to a shortage of combustion air, a problem in which exhaust gas components are disturbed, a fluctuation in the amount of steam generated due to heat recovery in a boiler, and a fluctuation in the amount of power generation. Also, in order to improve the followability of the combustion air blast volume in the secondary combustion chamber against fluctuations in the generated gas volume due to clinker dropping and collapse, the ratio (air ratio) of the air volume required for combustion of the generated gas is increased. However, if this is done, the surplus amount of combustion air will increase, and the heat recovery efficiency in the boiler will decrease, which will be a problem.

  In addition, if a thermometer is installed around the auxiliary tuyere installation section to measure the furnace temperature, and a thermometer is provided to adjust the air flow from the sub tuyere based on the measured value, the clinker will adhere. Due to the growth, the temperature measuring part of the thermometer is buried in the clinker, so that the temperature inside the furnace cannot be measured, and there is a problem that the amount of air blown from the sub tuyere cannot be adjusted.

  On the other hand, a pusher mechanism that reciprocates the pushing member toward the furnace so that the waste stays in the waste gasification and melting furnace, so-called bridging phenomenon, to break down and drop it. Document 2) has been proposed.

JP 09-060830 A JP-A-10-019221

  Even if the pusher mechanism described in Patent Document 2 for eliminating the bridging phenomenon of waste is applied to break down the clinker adhering to the inner wall surface of the gasification melting furnace, Because it is attached in a ring shape, even if it protrudes locally by the pushing member, even if the clinker can be removed at the position where this pushing member is provided, other parts that occupy a large range in the circumferential direction are destroyed. There is a problem that can not be.

The present invention has been made to solve the above-described problems, and the clinker adhering to the entire circumference in the circumferential direction of the inner wall surface of the gasification melting furnace is destroyed and dropped off, thereby preventing the occurrence of problems due to the clinker adhesion. An object of the present invention is to provide a clinker destruction / generation suppression device for a waste gasification and melting furnace that can be used.

The present invention discards the inner space of the furnace body, from below, the lower shaft portion to melt the thermal decomposition residue of the deposited coke by burning to form a high temperature combustion zone waste formed on the high-temperature combustion zone The main shaft for free decomposition of the waste in the material layer and the freeboard section are roughly divided, and the main tuyere that blows oxygen-enriched air into the lower shaft is provided. In a waste gasification and melting furnace equipped with a sub tuyere that blows air for decomposition, waste and dust are melted by the high-temperature area around the tip of the sub tuyere and the inner wall of the furnace near the sub tuyere The present invention relates to a clinker destruction / generation suppression device for a waste gasification and melting furnace that suppresses the generation of clinker while destroying and dropping the clinker generated by adhering to a lump .

In such a clinker destruction / occurrence suppression apparatus for waste gasification and melting furnace, the present invention provides a tangential component from a plurality of positions on the inner periphery of the furnace within a range from the height of the sub tuyere to a height of 1.5 m. A gas injection means for injecting a high-pressure gas of 0.5 MPa or more toward the inside of the furnace in a direction having a direction, and directing the injected gas in a direction along the inner wall surface of the furnace in the circumferential direction, the high-pressure gas being nitrogen or waste gas It is characterized in exhaust der Rukoto to be discharged is circulated from the reduction melting furnace.

According to the present invention configured as described above, even if the clinker starts to extend in the circumferential direction on the inner wall surface of the furnace at the tuyere position, the range from the tuyere height position to a height of 1.5 m above the tuyere at an appropriate time. By injecting nitrogen or exhaust gas exhausted from the waste gasification and melting furnace and circulated as a high-pressure gas of 0.5 MPa or more toward the furnace in a direction having a tangential component from a plurality of positions on the inner periphery of the furnace The clinker is effectively crushed and blown away by directing the jet gas in the circumferential direction along the inner wall surface of the furnace. Thus, the clinker is removed from the furnace inner wall surface in a wide range in the circumferential direction. In addition, by injecting gas at an appropriate time, it is possible to prevent waste and dust melts from adhering to the furnace inner wall, and to suppress the generation of clinker.

In the present invention, the gas injection means comprises a gas injection tube having a gas injection port, Ri interval 0.1~1.5m der in the horizontal plane of the gas injection port of the adjacent gas injection pipe, the gas injection port to Rukoto injection form of injection gas radially or cone is preferable. By carrying out like this, the injection gas from the said gas injection port will spread over the wide range in the circumferential direction of a furnace inner wall, and will expand the crushable range of a clinker.

As described above, according to the present invention, the clinker adhering to the entire circumference in the circumferential direction of the inner wall surface of the gasification melting furnace is destroyed and dropped, and the generation of the clinker is suppressed, so that the problem caused by the clinker adhering It is possible to provide a clinker destruction / generation suppression device for waste gasification and melting furnace that can prevent generation.

  That is, since the clinker adhesion growth on the inner wall surface of the gasification melting furnace can be prevented and the generation of clinker can be suppressed, the following effects can be obtained.

  -The clinker adhering to the inner wall of the furnace prevents the waste thrown in from the top from being stably lowered in the furnace, and waste and dust do not accumulate and remain on the clinker. The waste can be pyrolyzed and gasified smoothly, and the pyrolysis residue can be melted to improve the stability of the furnace operation.

  ・ The clinker attached to the inner wall of the furnace falls off and collapses, and the waste that remains on the clinker falls at once. Therefore, it is possible to prevent the amount of gas to be greatly changed, thereby causing fluctuations in the furnace pressure and preventing the stable operation of the gasification melting furnace from being hindered.

  ・ When combustible gas in the generated gas is burned in the secondary combustion chamber, the amount of combustion air supplied to the secondary combustion chamber cannot be adjusted to the fluctuation of the generated gas, and combustion is not possible. It becomes unstable and there is no problem of trouble in exhaust gas treatment caused by disturbance of exhaust gas components, and the amount of steam generated by heat recovery in the boiler is stabilized, and the power generation amount is stabilized.

  ・ In order to improve the followability of the amount of combustion air blown in the secondary combustion chamber against fluctuations in the amount of gas generated due to clinker dropping and collapse, the ratio (air ratio) of the amount of air necessary for combustion of the generated gas is increased. Therefore, it is possible to operate at a low air ratio, reduce the ratio of surplus combustion air, and improve boiler steam generation efficiency and power generation efficiency.

  ・ In the case of a furnace that installs a thermometer around the auxiliary tuyere installation area, measures the temperature in the furnace, and adjusts the amount of air blown from the sub tuyere based on the measured value, the temperature-sensing part is the clinker. Since it is not buried, accurate temperature measurement can be performed, and the amount of air blown from the sub tuyere can be accurately adjusted.

  ・ In the case of a furnace that measures the height of the waste layer and controls the blast volume, waste supply amount, coke supply amount, etc. of each tuyere, the measurement of the layer height is obstructed by the clinker Therefore, the measurement accuracy is improved. As a result, the controllability of these can be improved, and it is possible to surely stabilize the layer height and stabilize the operation.

It is a longitudinal cross-sectional view which shows the principal part of one Embodiment apparatus of this invention. It is a cross-sectional view of the apparatus of FIG. 1 at the height position of the gas injection means.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In this embodiment, the vertical waste gasification melting furnace is characterized by providing gas injection means, but prior to the description of these characteristics, the waste gasification melting furnace provided with these means The outline structure of will be described.

  The waste gasification and melting furnace of one embodiment of the present invention shown in FIG. 1 is a shaft-type waste gasification and melting furnace having a vertical shape, in which waste, auxiliary fuel, and slag are disposed in the upper part of the furnace body 1. An inlet (not shown) for introducing the component adjusting material of the furnace into the furnace is provided, and an exhaust gas outlet (not shown) for discharging the exhaust gas in the furnace to the outside of the furnace on the upper side. Is provided. In addition, an outlet 2 for discharging molten slag and molten metal is provided at the furnace bottom of the furnace body 1.

  The waste gasification and melting furnace has an internal space of the furnace body 1 divided into three regions in the vertical direction. From the lower side, a lower shaft part I formed in the lower part of the furnace, and a middle shaft located on the lower shaft part I Part II is an area having a free board part III formed at the top. Each of these parts I, II, and III is an area having the following functions. That is, the lower shaft portion I is a region where the deposited coke is burned to form a high-temperature combustion zone, and the middle shaft portion II is a waste layer formed by the accumulation of waste put on the high-temperature combustion zone. The area where the waste is pyrolyzed, the free board part III, is an area where the generated combustible gas is partially combusted.

  Above the furnace body 1 of the waste gasification and melting furnace, a supply device (not shown) for supplying waste such as municipal waste, coke used as auxiliary fuel, and limestone used as a component adjusting material for the generated slag ), Waste, coke, and limestone supplied from this supply device are conveyed by a conveyor (not shown) and charged into the furnace through the inlet at the top of the furnace.

  A tuyere for blowing oxygen-containing gas is provided on the furnace wall for each of the lower shaft portion I, the middle shaft portion II, and the freeboard portion III formed in the waste gasification melting furnace. That is, the lower shaft portion I is provided with a main tuyere 3 that burns the deposited coke to form a high-temperature combustion zone and blows in oxygen-enriched air for melting the pyrolysis residue, and the middle shaft portion II Is provided with a sub tuyere 4 that blows air for causing thermal decomposition while partially burning the waste that has been thrown in and deposited, and in the freeboard section III, A three-stage tuyere (not shown) for blowing air for partially burning the combustible gas generated by pyrolysis and maintaining the inside at a predetermined temperature is provided.

  In this embodiment, the furnace body 1 that forms the three regions of the lower shaft portion I, the middle shaft portion II, and the free board portion III in the internal space is provided with gas injection means on the furnace wall in this embodiment.

  FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 at the height position of the gas injection means. As shown in FIGS. 1 and 2, the gas injection pipe 5 as the gas injection means is a furnace in a range from the height position of the sub tuyere 4 of the furnace wall of the furnace body 1 to a height of 1.5 m above. A gas is injected from a plurality of positions on the inner periphery toward the furnace in a direction having a tangential component, and a plurality of gas injection ports 5 </ b> A are provided at the furnace inner end of the gas injection tube 5. Here, the direction having a tangential direction component means other directions excluding a pure radial direction, and includes not only the horizontal plane but also the direction inclined with respect to the horizontal plane and the vertical direction. In the example of FIG.1 and FIG.2, the case where it injects in the tangent direction in a horizontal surface and an up-down direction is shown. It is preferable that the space | interval in the horizontal plane of the gas injection port of the said adjacent gas injection pipe is 0.1-1.5m.

  The reason why the gas injection pipe 5 is provided at a height of 1 to 1.5 m above the sub tuyere 4 is the range from the height position of the sub tuyere 4 of the furnace wall of the furnace body 1 to a height of 1.5 m above. Then, the upper part from the tip of the auxiliary tuyere is locally heated (overheated), and waste and dust melt and adhere to the inner wall of the furnace due to the formation of a high temperature region by this local heating. This is because it corresponds to the range in the height direction in which the clinker 20 is generated. Further, the waste 21 remains above the clinker 20.

  The reason why the interval in the horizontal plane of the gas injection ports of the adjacent gas injection pipes is preferably 0.1 to 1.5 m is that if the interval is smaller than 0.1 m, the air flow between the injected gases interferes. This is because the clinker adhering to the inner wall surface of the furnace does not hit effectively, and if the interval is larger than 1.5 m, there is a portion of the inner periphery of the furnace where the jet air current does not hit.

  The gas injection pipe 5 can be supplied with a high-pressure gas from the outside and inject it from the gas injection port 5A.

  As the high-pressure gas to be injected into the furnace, it is desirable to use nitrogen so as not to affect the thermal decomposition reaction of waste in the furnace, and it is preferable to inject at a pressure of 0.5 MPa or more. . The exhaust gas may be circulated as a high pressure gas.

  If the gas injection port 5A is an injection port in which the injection shape of the injected gas is radial or cone-shaped, gas can be injected over a wide range.

  By providing the gas injection means in this way, even if the clinker starts to extend in the circumferential direction around the sub tuyere position so as to extend in the circumferential direction, the height of 1.5 m above the height of the sub tuyere is appropriately set. The clinker is crushed and blown away by the injected gas by injecting the gas from the plurality of positions on the inner periphery of the furnace in the range up to this point toward the furnace in a direction having a tangential component. Thus, the clinker is removed from the furnace inner wall surface in a wide range in the circumferential direction. In addition, by injecting gas at an appropriate time, it is possible to prevent waste and dust melts from adhering to the furnace inner wall, and to suppress the generation of clinker.

  Moreover, if the space | interval in the horizontal surface of the gas injection port of an adjacent gas injection pipe shall be 0.1-1.5 m, the injection gas from the said gas injection port will cover the wide range in the circumferential direction of a furnace inner wall. As a result, the clinker crushable range or the clinker generation suppression range is expanded.

  The operation of the waste gasification melting furnace in the present embodiment configured as described above is performed as follows.

  Waste, coke, and limestone from the supply device are respectively charged into the furnace by a predetermined amount through an inlet (not shown) provided in the upper part of the furnace body 1, and the main tuyere 3, the sub tuyere 4, And from the three stage tuyere (not shown), oxygen-enriched air or air is blown into the furnace, respectively. Waste introduced from the inlet is deposited on the middle shaft portion II in the furnace to form a waste layer, and from the hot gas rising from the high temperature combustion zone of the lower shaft portion I and the sub tuyere 4 It is dried by blown air and then pyrolyzed. The combustible gas generated by pyrolysis is combusted by the air blown from the three-stage tuyere (not shown) in the free board part III and maintained at a temperature of 850 ° C. or higher, and decomposes harmful gas and tar content. After the treatment to be performed, the fuel is sent to a secondary combustion furnace provided outside the furnace, and the combustion gas is heat recovered by a boiler, a gas turbine, or the like. The residue resulting from the thermal decomposition of the waste in the waste layer of the middle shaft part II descends, reaches the lower shaft part I where the high temperature combustion zone where the coke is burned is formed, and remains in the lower shaft part I The fixed carbon that burns burns, and the incombustible material melts into molten slag and molten metal. Molten slag and molten metal are discharged from the tap 2 and supplied to a water granulator provided outside the furnace to be cooled and solidified, and the cooled and solidified granulated slag and granulated metal are recovered.

  In the present embodiment, gas is injected from the gas injection port 5A at an appropriate time when the clinker 20 is considered to have adhered to the inner wall surface of the furnace. By doing so, the clinker 20 is crushed and dropped to be removed. In addition, by injecting gas at an appropriate time, it is possible to prevent waste and dust melts from adhering to the furnace inner wall, and to suppress the generation of clinker.

4 Sub tuyere 5 Gas injection means (gas injection pipe)
5A Gas injection port 20 Clinker

Claims (2)

The internal space of the furnace body, from the bottom, burns the deposited coke to form a high-temperature combustion zone and melts the pyrolysis residue of the waste, and discards the waste layer formed on the high-temperature combustion zone The main shaft for freely decomposing materials is divided into a freeboard section, and a main tuyere that blows oxygen-enriched air into the lower shaft section is provided, and the middle shaft section is used for partial combustion and pyrolysis of waste. In a waste gasification and melting furnace equipped with a secondary tuyere that blows air, waste and dust are melted by the high temperature region around the tip of the secondary tuyere and adhere to the inner wall of the furnace near the sub tuyere. A clinker destruction / generation suppression device for a waste gasification and melting furnace that suppresses the generation of clinker while destroying and dropping the generated clinker ,
From a range in a furnace a plurality of positions in the circumferential from the height position of the sub tuyere to a height of 1.5m above, by injecting high pressure gas above 0.5MPa towards the furnace in a direction having a tangential component, injection comprising a gas injection means for directing in the direction along the gas into the furnace wall surface in the circumferential direction, waste gas, wherein the exhaust gas der Rukoto that the high-pressure gas is discharged circulating nitrogen or waste gasification melting furnace Crinker destruction / generation suppression device for chemical melting furnaces. Gas injection means comprises a gas injection tube having a gas injection opening, Ri interval 0.1~1.5m der in the horizontal plane of the gas injection port of the adjacent gas injection pipe, the injection gas injection port of the injection gas destruction generation control apparatus clinker waste gasification melting furnace according to claim 1, to Rukoto shape in radial or conical.

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