JP5538771B2 - Waste melting treatment method - Google Patents

Description

  The present invention relates to a method for melting a waste using a massive carbon-based combustible material such as coke.

  As a method for treating waste such as general waste and industrial waste, for example, there is a method of melting waste using coke as a combustion agent. The processing method by melting can recycle incinerated ash and non-combustible waste, which have been finally disposed of by landfill, into slag.

  As a melting treatment of waste, there is a method of incineration in an incinerator and heating and melting the incinerated ash and incombustible components in a melting furnace. However, in recent years, attention has been focused on gasification and melting furnaces capable of performing combustion and gasification of combustible components in waste and heating and melting of ash in waste in one furnace.

  If the types of waste, such as general waste and industrial waste, differ, the ratio of components such as moisture, combustible content, and ash content will differ. Furthermore, even in the same type, the component ratio varies depending on the location and timing of collecting the waste. For this reason, depending on the component ratio in the waste, the ventilation resistance of the packing layer formed in the furnace (that is, the input such as waste or the deposition layer of the product in the furnace (such as carbonization residue)) increases, and the furnace In some cases, the operation status of the plant becomes worse, and the processing cost increases.

  For example, shredder dust generated during dismantling of discarded automobiles and home appliances, for example, is finer particles such as earth and sand and glass than general waste such as municipal waste as exemplified in Patent Document 1. Since there is much content, it contains a lot of ash, and it may be finely cut by a shredder device, which tends to increase the air flow resistance of the filler layer. In this case, the air blown from the tuyere at the bottom of the furnace or the oxygen-enriched air is difficult to diffuse around the tuyere to gasify and melt the waste, and the combustion gas is formed in the layer with few voids in the packing layer. Concentrate and increase ventilation resistance. In some cases, a channeling phenomenon may occur.

  Such poor ventilation of the packed bed lowers the heat exchange rate in the lower part of the furnace and hinders the molten metal from the bottom of the furnace. Furthermore, in order to compensate for a decrease in the heat exchange rate at the lower part of the furnace, an operation is required in which the amount of coke that is a combustion agent is increased to 250 to 350 kg per ton of waste. As a result, waste disposal costs have risen.

  On the other hand, in Patent Document 2, in order to prevent the in-furnace air permeability from deteriorating due to the fallen refractory material sprayed to repair the furnace wall, a clearance is secured on the stock level surface prior to repair work. It is disclosed to charge the material. However, the method of Patent Document 2 can only prevent temporary deterioration of air permeability during re-operation after repair work, and cannot prevent poor ventilation that occurs in the furnace during operation.

Japanese Patent No. 3984484 JP 2005-23392 A

  That is, the present invention has been made to solve the above-mentioned problem given as an example, and its purpose is to prevent a poor ventilation from occurring in the packing layer formed in the furnace during the melting process. An object of the present invention is to provide a waste melting treatment method that can be prevented.

  Another object of the present invention is to provide a waste melting treatment method that can reduce the cost of waste treatment by reducing the amount of massive carbon-based combustible material such as coke.

The waste melting treatment method according to the present invention is a waste melting treatment method in which waste and a massive carbon-based combustible material are charged into a furnace, and ash content in the waste melted in the furnace is discharged from the bottom of the furnace. The material contains fine particles that impede the breathability in the furnace, and put a ventilation ensuring material mainly composed of incombustible materials that reach the heating and melting region at the bottom of the furnace without being gasified into the furnace, By ensuring a gap for ventilation in the packing layer formed in the furnace, it is possible to suppress a decrease in the air permeability in the furnace due to fine particles. small cans, beverage cans, beverage bottles, and features that you have mainly the incombustible material drums.

As another aspect, the waste melting treatment method according to the present invention is a waste melting method in which waste and a massive carbon-based combustible material are charged into a furnace, and ash in the waste melted in the furnace is discharged from the bottom of the furnace. In the treatment method, the waste contains fine particles that impede air permeability in the furnace, and the airflow securing material mainly composed of incombustible material that reaches without being gasified to the heating and melting region in the lower part of the furnace. By introducing 0.03m ³ to 0.5m ³ per ton of waste input into the furnace and ensuring a void for ventilation in the packing layer formed in the furnace, It is characterized by suppressing a decrease in air permeability in the furnace . In addition, it is preferable to introduce the air flow securing material so as to be scattered in the height direction of the packing layer in order to ensure the ventilation of the packing layer formed in the furnace during operation.

  The kind of waste is not limited, and shredder dust can be input instead of the waste or together with the waste. Based on the viewpoint of saving the manufacturing cost, it is preferable that the amount of the massive carbon-based combustible material introduced into the furnace as the combustion agent is 150 kg or less per ton of waste input. Moreover, as a ventilation ensuring material, for example, a steel empty can can be semi-crushed or completely crushed. Further, it is preferable that the ventilation ensuring material is introduced while air or oxygen-enriched air is blown into the furnace.

  According to the waste melting treatment method according to the present invention, the waste material and the ventilation ensuring material are charged, and the voids for ventilation are secured in the packing layer formed in the furnace. It is possible to prevent the occurrence of poor ventilation in the filler layer during the execution of.

  Furthermore, if the aeration state of the packing layer is good, the molten metal is quickly discharged, so that it is possible to prevent a reduction in the amount of waste treated in the furnace. In addition, since heat conduction to the lower part of the furnace becomes good, the amount of wasted coke input can be reduced. As a result, waste disposal costs can be saved.

1 is a longitudinal sectional view of a melting furnace to which a waste melting method according to a preferred embodiment of the present invention is applied. It is a characteristic view which shows the relationship between the input amount of the ventilation ensuring material according to the said embodiment, a coke mixing ratio, and a lower stage blowing pressure. It is a characteristic view which shows the relationship between the input of the ventilation ensuring material according to the said embodiment, and a furnace top temperature. It is a schematic diagram for demonstrating the state of the filler layer formed in the said melting furnace. It is a characteristic view which shows the time-dependent change of the lower stage blowing pressure and the amount of hot water for the melting furnace.

  Hereinafter, a waste melting method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the technical scope of the present invention is not construed as being limited by the embodiments described below.

  FIG. 1 shows a longitudinal sectional view of a shaft type gasification melting furnace (hereinafter simply referred to as “melting furnace”) used for carrying out the waste melting treatment method according to the present embodiment. The melting furnace 1 has a furnace body 2 formed in a cylindrical shape, for example, for melting waste gas in a low oxygen state to gasify and melt ash and incombustible components. The furnace main body 2 has a charging port 21 for charging auxiliary materials such as waste and coke, a ventilation ensuring material, and the like at the top of the furnace, and a tapping port 22 for taking out the melt at the bottom of the furnace. An exhaust port 23 for discharging the gas generated from the waste or the gas blown into the furnace is provided at the top. The hot water outlet 22 can be opened and closed by an opening and closing mechanism (not shown), for example, and the melt can be taken out intermittently. Further, a melt tank 24 is provided at the bottom of the furnace for supplying the melt taken out from the tap 22 to the granulated pit 3. Although the detailed illustration is omitted, the granulated pit 3 takes out a casing for storing cooling water for cooling and solidifying the melt and a melt (that is, slag and metal) cooled and solidified in the casing. A scraper conveyor is provided.

  The furnace body 2 forms a straight body part (so-called shaft part) 25, an inverted conical part (so-called morning glory part) 26, and a furnace bottom part 27 from the furnace upper part toward the furnace bottom part. Although not limited, the upper side of the straight body part 25 mainly constitutes a drying region where waste is dried and preheated, and the upper side of the inverted conical part 26 from the lower side of the straight body part 25 is mainly used. The combustible component in the waste constitutes a gasification region where pyrolysis gasification is performed, and the lower part of the furnace in which the coke bed is formed constitutes a heating and melting region in which mainly ash, dry distillation residue and the like are melted. Furthermore, the furnace bottom 27 constitutes a liquid pool for storing the melt. The temperature in the drying region is, for example, 500 to 700 ° C, desirably 450 to 650 ° C. Moreover, the temperature of a heat-melting area | region is 1600-2000 degreeC, for example.

  In the lower part of the furnace, coke constituting the coke bed and air for burning combustible carbonization residue (fixed carbon) or oxygen-enriched air (hereinafter simply referred to as “air etc.”) are supplied into the furnace. A plurality of ventilation tuyere (lower tuyere) 4 are arranged in the circumferential direction. The air blown from the lower tuyere 4 is preferably set so that the blowing pressure is within the range of 10 to 25 kPa, for example. The oxygen-enriched air is air whose oxygen concentration has been increased by mixing oxygen from the oxygen generator 41, for example. Further, a plurality of blower tuyere (upper tuyere) 42 for supplying air or the like for burning waste into the furnace is arranged on the side wall of the straight body part 25 and / or the inverted conical part 26 in the circumferential direction. FIG. 1 shows an example of arrangement in the straight body portion 25. In addition, the height which arrange | positions the upper tuyere 42 and the lower tuyere 4 is not limited to the height shown in FIG. 1, and can be changed suitably. Further, an auxiliary tuyere may be added to promote combustion of waste that descends on the furnace wall side of the straight body portion 25.

  Air blown into the furnace through the lower tuyere 4, the upper tuyere 42 and the auxiliary tuyere can be supplied using a blower 43. When blowing oxygen-enriched air, an oxygen generator 41 is connected to the air flow path from the blower 43. FIG. 1 illustrates a configuration in which air enriched with oxygen from the lower tuyere 4 and air from the upper tuyere 42 are blown.

  The type of waste to be treated in the melting furnace 1 is not particularly limited, and may be any waste such as shredder dust, excavated waste, incinerated ash, or the like, or a mixture of these and combustible waste. May be. Carbonized waste may be input. FIG. 1 illustrates, as an example, a configuration in which general waste such as shredder dust (ASR) and municipal waste is mixed. The shredder dust and the general waste thrown into the respective hoppers 5, 51 are conveyed to the upper part of the furnace by, for example, the conveyor 51, and put into the furnace through the inlet 21. Shredder dust and general waste may be separately put into a furnace for treatment, or both are put into the furnace, for example, so that the weight ratio of shredder dust in the furnace is 35 to 80%. May be processed. At this time, auxiliary materials such as coke and limestone and a ventilation ensuring material are also introduced into the furnace together with the waste. These auxiliary raw materials and ventilation ensuring materials can also be put into the furnace using a conveyor.

  In this embodiment, the input amount of coke is preferably 150 kg or less, and particularly preferably 60 kg or less, per ton of waste input to be charged into the furnace. However, these are target values at the time of steady operation, and do not limit input of more.

  Furthermore, in this embodiment, in order to ensure the space | gap for ventilation | gas_flowing in a filler layer, a ventilation ensuring material is supplied in a furnace with a waste material. The material and shape of the ventilation ensuring material are not particularly limited. However, if gasification occurs before reaching the lower part of the furnace where poor ventilation occurs, the filler layer cannot be sufficiently ventilated, so that flammable materials such as wood and plastic are ineligible. Therefore, it is preferably an incombustible material that can reach the heating and melting region at the lower part of the furnace without being gasified. However, it is not necessary to be formed of only non-combustible material, and a part of combustible part may be included.

  The ventilation ensuring material may be any non-combustible material, but it is not suitable if it does not gasify but almost melts before reaching the lower part of the furnace. Preferable aeration securing materials include cans (for example, ˜18 liters), pail cans (for example, ˜20 liters), round cans, beverage cans (including canned foods), beverage bottles, drums (eg, 18 to 200 Liters) and other non-combustible materials. These air flow securing materials are finally melted to become slag or metal, so it is not economical to newly manufacture or purchase them, and are selected from general waste and industrial waste Is preferably used. In this case, the original shape may be left as it is, or it may be crushed to some extent (half crushed or fully crushed). Moreover, the contents which the contents remained may be sufficient and it may be empty. Steel cans are collected as metal, and aluminum cans and bottles are collected as slag. Therefore, the steel can is preferable because of its high recycling value. In addition to this, non-combustible materials such as glass fiber-based molded heat insulating materials, slate, pots and kettles can also be used as a ventilation ensuring material.

Vent securing member is preferably inserted from the waste charged per ton 0.03 m ³ to be within a range of 0.5 m ^3. In addition, the volume of a ventilation ensuring material shows the volume containing a space | gap. When the input amount of the air flow securing material is less than 0.03 m ³ , although the air gap for the air flow is formed in the filler layer, the effect of improving the air flow and the coke input amount is small. On the other hand, if the amount of the ventilation securing material is more than 0.5 m ³ , the effect of improving ventilation and coke charging will reach its peak, and the top temperature rises due to excessive ventilation. A problem occurs.

Table 1 below shows an example of the data of the blowing pressure of the lower tuyere 4, the amount of coke input, the top temperature of the furnace, and the amount of waste disposal obtained by introducing the ventilation ensuring material into the actual melting furnace 1. . 2 and 3 are graphs of the results shown in Table 1. In addition, although Table 1 has shown as an example what processed the waste which uses shredder dust in the ratio of 50 to 60% using a funnel can as a ventilation ensuring material, the ventilation ensuring materials other than a funnel can are used. The same tendency was observed when used or when the ratio of shredder dust was changed.

As can be seen from FIG. 2, the amount of coke and the blowing pressure are rapidly improved by introducing a material for ensuring ventilation, but the effect can be stably obtained when the amount of input is 0.03 m ³ . It is from around. After that, the improvement effect obtained by increasing the input amount of the ventilation ensuring material increases, but it reaches a peak when the input amount exceeds 0.5 m ³ . Therefore, it is not economical to increase the input amount of the air flow securing material. In addition, when shredder dust is included, there is a concern that the copper concentration in the metal is diluted and the resource value for copper refining is lowered if too much iron-based ventilation ensuring material is added.

On the other hand, as can be seen from FIG. 3, the furnace top temperature (that is, the gas temperature discharged from the melting furnace) increases as the amount of the aeration securing material increases. The reason for the rise in the furnace top temperature is that the gas flow through the packing layer is improved and the contact between the hot gas generated in the lower part of the furnace and the packing in the furnace and heat transfer are suppressed. It is. As a result of the suppression of heat transfer, the temperature rise of the waste is delayed, and the waste treatment speed is reduced as shown in FIG. As described above, the temperature of the drying region is, for example, 500 to 700 ° C. When the temperature is higher than that, low boiling point compounds (for example, CaCl ₂ ) included in the dust accompanying the gas discharged from the melting furnace tend to be in a semi-molten state. Such a semi-molten product of dust adheres to and grows on the inner wall of the pipe, and when it finally becomes blocked, the operation of the furnace must be stopped and removed. Therefore, in combination with the results shown in FIG. 2, it is preferable that the input amount of the ventilation ensuring material is 0.5 m ³ or less per ton of waste.

  The ventilation ensuring material can be put into the furnace by supplying it to the conveyor 51 at point P in FIG. However, the present invention is not limited to this, and it may be directly fed to the upper part of the furnace. Furthermore, it is not always necessary to mix and throw in waste, and the waste or coke may be fed separately by using another conveyor or using a crane or the like. However, in order to ensure the ventilation of the packed bed that is fluidly formed in the furnace during operation, it is necessary to introduce a ventilation ensuring material during the operation. There is no point in just putting it on top. In other words, it is preferable to add the air flow securing material so as to be scattered in the height direction of the filler layer. It should be noted that it is preferable to always supply the ventilation ensuring material during operation. However, based on the economical viewpoint and the resource value for copper refining described above, it can also be supplied only when the ventilation in the furnace deteriorates. . Whether or not the ventilation in the furnace has deteriorated is determined by, for example, an increase in the blowing pressure, a decrease in the amount of hot water discharged from the melt.

  When the waste is melted in the melting furnace, the waste thrown into the furnace together with a predetermined amount of coke is dried and pyrolyzed by the high-temperature gas flowing in the opposite direction as it descends the furnace. The amount of waste input can be determined by the capacity of the furnace. The heat sources for drying and pyrolysis of waste are the heat of combustion of waste by air blown from the upper tuyere 42 and the heat of combustion of coke by air blown from the lower tuyere 4 or oxygen-enriched air. used.

  The combustion gas of the combustible carbonization residue of coke and waste reaches the maximum temperature at the upper end of the coke bed formed in the lower part of the furnace, the ash is melted in this region, and the melt drops in the coke bed voids. The dripped melt is temporarily stored in a liquid pool at the bottom of the furnace, and is taken out intermittently by opening the hot water outlet 24.

  FIG. 4 is a diagram schematically showing a change in the state of the packing layer when the ventilation ensuring material is introduced into the furnace in which the ventilation has deteriorated. As schematically shown in FIG. 4 (a), if no airflow securing material is used, depending on the components of the waste, some incombustibles such as earth and sand, glass, etc. in the shredder dust may be deposited on the morning glory part 26 or the lower part of the furnace. Fine particles such as dry distillation residue accumulate, voids are reduced, and the airflow resistance of the packing layer tends to increase. In this case, air or the like blown from the lower tuyere 4 is difficult to diffuse around the tuyere, and a low temperature part is generated in the lower part of the furnace. Further, since the combustion gas is concentrated in a small gap, the gas flow rate is locally increased, the ventilation resistance is increased, and a channeling phenomenon may occur.

  Therefore, if the ventilation ensuring material is introduced in accordance with the present embodiment, as schematically shown in FIG. 4 (b), the ventilation ensuring material descends in a state where the shape is maintained to the lower part of the furnace. A void for forced ventilation is formed in the packing layer on the lower side of the furnace. As a result, air or the like from the lower tuyere 4 starts to diffuse around the tuyere, and the low temperature part at the lower part of the furnace is eliminated. And combustion gas diffuses uniformly in a furnace bottom part or a furnace bottom part, therefore, ventilation resistance becomes small and channeling does not occur. Accordingly, heat conduction at the bottom of the furnace and at the bottom of the furnace is activated. As a result, the temperature of the melt rises and the voids in the packed bed increase, so that the hot water is quickly discharged out of the furnace. This reduces the amount of oxygen lances and the like that are hot water aids.

  As described above, when the heat conduction at the bottom of the furnace and the bottom of the furnace is activated, the amount of coke that is a combusting agent can be reduced, and the processing cost can be reduced by reducing the amount of input. . As described above, in the past, the operation in which the input amount per ton of waste was increased to 250 to 350 kg was forced, but according to the present embodiment, the input amount per ton of waste is reduced to 150 kg or less. And its economic value is extremely large.

  In addition, the occurrence of channeling can be prevented by improving the ventilation of the filler layer. As a result, it is possible to suppress a phenomenon in which a large amount of residue such as char is blown up in a short time. Furthermore, since the temperature fluctuation of the combustion chamber installed in the latter stage is stabilized, it is possible to suppress the occurrence of clinker (ash semi-melt) in the combustion chamber.

  Furthermore, since the ventilation of the packed bed is improved, the combustion at the bottom of the furnace and the bottom of the furnace is made uniform, so that it is possible to suppress, for example, the temperature locally falling and the semi-dissolved material adhering to the tuyere. . That is, it is possible to prevent the luminance of the lower tuyere from being lowered.

  In addition, according to this embodiment, there is an advantage that the amount of dry distillation residue such as char is stabilized and temperature fluctuations in the combustion region are stabilized.

  FIG. 5 shows an example of the change over time of the blowing pressure and the amount of hot water of the melting furnace in which the ventilation ensuring material is actually added. As can be seen from the results of FIG. 5, the ventilation pressure is lowered and the amount of discharged hot water is increased by introducing the ventilation ensuring material. That is, it is clear that the ventilation in the furnace is improved by this embodiment.

  As described above, according to the waste melting method of the present embodiment, the waste and the ventilation ensuring material are put into the furnace, and a void for ventilation is secured in the packing layer formed in the furnace. By doing so, it is possible to prevent the occurrence of poor ventilation in the packing layer during operation when performing the melting process.

  Furthermore, if the aeration state of the packing layer is good, the molten metal is quickly discharged, so that it is possible to prevent a reduction in the amount of waste treated in the furnace. In addition, since heat conduction to the lower part of the furnace becomes good, the amount of wasted coke input can be reduced. As a result, waste disposal costs can be saved.

  In addition, although the shaft type gasification melting furnace is mentioned as an example in the above-mentioned embodiment, it may be a melting furnace using a massive carbon-based combustible material, and the type of the furnace is not limited. Other examples include a melting furnace exclusively for ASR and having only a morning glory part and a melting furnace mainly composed of incinerated ash without a shaft part. In addition, it can be applied to blast furnaces and cupola furnaces.

  Although the present invention has been described in detail with reference to specific embodiments, various substitutions, modifications, changes, etc. in form and detail are defined in the claims. It will be apparent to those skilled in the art that this can be done without departing from the spirit and scope. Therefore, the scope of the present invention should not be limited to the above-described embodiments and the accompanying drawings, but should be determined based on the description of the claims and equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Furnace main body 21 Input port 22 Hot water outlet 23 Exhaust port 4 Lower tuyere 42 Upper tuyere

Claims (5)

In a waste melting treatment method in which waste and a massive carbon-based combustible material are charged into a furnace, and ash content in the waste melted in the furnace is discharged from the bottom of the furnace.
The waste contains fine particles that impede breathability in the furnace,
A ventilation ensuring material mainly composed of incombustible materials that reach the heating and melting region at the bottom of the furnace without being gasified is introduced into the furnace, and a space for ventilation is secured in the filling layer formed in the furnace. By suppressing the decrease in the air permeability in the furnace due to the fine particles , the airflow securing material is mainly composed of non-combustible materials such as Ito, cans, round cans, beverage cans, beverage bottles, and drum cans. A waste melting method characterized by the above. In a waste melting treatment method in which waste and a massive carbon-based combustible material are charged into a furnace, and ash content in the waste melted in the furnace is discharged from the bottom of the furnace.
The waste contains fine particles that impede breathability in the furnace,
The vent securing material mainly composed of non-combustible material to reach without being gasified to the heating melting area of the furnace bottom to 0.5 m ³ charged from the waste charged per ton 0.03 m ³ into the furnace, the furnace A waste melting treatment method characterized in that a decrease in air permeability in the furnace due to the fine particles is suppressed by securing a space for ventilation in the packing layer formed in the above . Said vent securing material, waste melt processing method according to claim 1 or 2, characterized in that introducing such scattered in the height direction of the packing layer to be formed in the furnace. The waste melting method according to any one of claims 1 to 3 , wherein shredder dust is charged instead of or together with the waste. The waste melting method according to any one of claims 1 to 4 , wherein an input amount of the massive carbon-based combustible material is 150 kg or less per ton of waste input amount.