JP2000249470A - Treating method of composite waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat composite waste perfectly and efficiently through melting treatment without disassembling and classifying the same by a method wherein the upper end level of a coke bed is set between an upper end tuyere and a lower end tuyere while ordinary temperature and oxygen-enriched air is blown through the lower end tuyere into the coke bed. SOLUTION: The upper end level of a coke bed 13 is set between a lower end tuyere 9a and an upper end tuyere 9b. In this case, the char of waste under a condition that the composite waste is charged and distillated in a preheating process contains much amount of iron content other than C. Accordingly, when C in the char of the waste is burnt by oxygen-enriched air, an effect in operation is big. Further, ordinary temperature and oxygen-enriched air, containing 2% or more amount of enriching oxygen, is blown from the lower end tuyere 9a. The reason why the oxygen enriching amount of the ordinary temperature oxygen-enriched air is specified to be 2% or more is that the maintenance of coke bed temperature under the ordinary temperature air is difficult if it is less than 2%, and it becomes an obstacle to the combustion of char of waste and the temperature rise of slag and metal after melting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of melting and treating a complex waste such as waste home appliances containing metals and plastics by a multifunctional melting furnace, and more particularly to a method of melting the same with a total iron content of 1%.
0% <TotalFe (hereinafter referred to as “T.Fe”)
The present invention relates to a method for treating a composite waste capable of melting and processing 80% of the composite waste.

[0002]

2. Description of the Related Art Waste home appliances such as used washing machines, refrigerators and air conditioners are complex wastes containing metals, plastics, rubber and the like. Conventionally, such a composite waste, despite containing valuable metal materials such as iron, aluminum, and copper, has been disintegrated and crushed into small pieces as a whole and landfilled at a final disposal site.

[0003] However, due to the shortage of the final disposal site and the enactment of a new recycling law, a recycling demonstration plant and the like have been constructed, and attempts have been made to separate complex wastes to collect useful metal materials. . That is, the composite waste is classified according to the product type such as a washing machine and a refrigerator,
After extracting dangerous substances such as a cooling medium and a lubricating oil, the components are disassembled for each component and member, and the disassembled pieces are separated for each raw material such as metal or plastic, and a process according to the raw material is performed. For example, the separated metal waste is charged into a melting furnace together with coke and the like to be melted, and the separated plastic is crushed and landfilled.

[0004] Such a separation treatment method is an effective means in that valuable metal materials can be recovered and crushed pieces to be landfilled can be reduced. But,
The dismantling and sorting of complex waste requires a great deal of labor, and the increase in man-hours has led to high costs, which has been a hindrance to forming a recycling-based society. In particular, the trend has become remarkable in today's diversified home appliances.

[0005] In recent years, attention has been paid to the development of a method of recovering a valuable metal material by directly charging a composite waste into a vertical melting furnace without separating the composite waste, and performing a melting treatment. As a technique related to this, for example, in Japanese Patent Application Laid-Open No. Hei 5-222424, an invention relating to "a disposal method for protecting the environment of organic and inorganic non-metal accompanying substances of used vehicles or used equipment" has been proposed. I have.

[0006] The present invention is based on the concept of "adding incidental substances together with steel scrap of a used vehicle or used equipment to a furnace,
Ancillary substances are chemically reacted with iron oxides contained in steel scrap or iron ore, and the entrained incidental substances are used as a flux for chemically reducing and forming slag, such as coke, oil or gas. It supplements at least in part conventional fluxes for this purpose. And to dispose of the environment-friendly disposal of organic and inorganic non-metallic accompanying substances of used vehicles or other mass-produced products such as washing machines and refrigerators.

[0007]

By the way, complex waste contains a large amount of plastics. Even when plastics are contained, the garbage melting furnace does not generate harmful substances. It can be processed safely. However, since the temperature of the waste gradually rises as it descends in the furnace, the plastics are thermally decomposed and gasified before arriving at the lower part of the furnace. Is not effectively utilized during high-temperature melting.

Further, the invention relating to the disposal method disclosed in Japanese Patent Application Laid-Open No. 5-222424 discloses a disposal method for crushed metal scraps or partially dismantled used vehicles or used equipment. In addition, there is no attempt to melt the composite waste without dismantling it.

Further, in this waste treatment method, means for controlling a preheating zone, a combustion zone, and a melting zone in a vertical furnace, a balance of gas, slag, and hot metal as products, and whether combustion exhaust gas is complete combustion or partial combustion. , Combustion space required, charging method (necessity of gas flow control), peripheral flow formation, central flow formation, air blowing conditions for multi-stage blowing, main tuyere upper tuyere or lower tuyere No specific processing conditions such as are considered.

In view of the above problems, it is an object of the present invention to effectively utilize the high calorific value of plastics at the time of high-temperature melting and the ability as a reducing agent, and to set specific processing conditions to form a composite. It is an object of the present invention to provide a composite waste treatment method capable of safely and efficiently melting a waste without dismantling and separating the waste.

[0011]

In order to achieve the above object,
According to the present invention, a composite waste containing at least a metal and a plastic is charged together with coke into a multifunctional melting furnace having a multi-stage tuyere and dried, thermally decomposed, burned, and melted to melt the composite waste. At the same time, the composite waste is charged together with dust agglomerate as a raw material, the upper end level of the coke bed is set between the upper tuyere and the lower tuyere, and oxygen at room temperature is fed from the lower tuyere to the coke bed. It blows enriched air.

In this treatment method, the total iron content of the composite waste is 10% <T. Suitable when Fe <80%.

Further, it is preferable that the oxygen-enriched amount of the oxygen-enriched air at room temperature is 2% or more.

Further, it is preferable to cool the upper part in the furnace by blowing steam from the upper tuyere.

Further, it is preferable that the tuyere blowing amount is set such that the upper tuyere blowing amount> the lower tuyere blowing amount.

Further, it is preferable to blow the waste plastic together with the oxygen-enriched air at room temperature from the lower tuyere.

It is preferable to change the stock level of the charge to control the rate of temperature rise of the raw fuel in the furnace.

In addition, a large-diameter composite waste which is not dismantled in the center of the furnace and a composite waste having a high metal content among the crushed composite wastes are mixed with the large-diameter coke and charged. Of the composite waste after crushing, those with low metal content,
It is preferable that the dust agglomerate be mixed with small-diameter coke and charged into the periphery.

Further, it is preferable to charge a composite waste as a raw material together with dust agglomerate and iron scrap.

Then, a large-diameter composite waste which is not dismantled, a composite waste having a high metal content among crushed composite wastes, and iron scrap mixed with a large-diameter coke are charged into the furnace. It is preferable to charge the mixed waste having a small metal content and the dust agglomerate with the small-diameter coke in the peripheral portion.

According to the present invention, the composite waste such as waste home appliances is charged together with the dust agglomerate as a raw material when the composite waste is melted. Dust agglomerate is charged because the heat surplus is used for the reduction endotherm of the dust agglomerate and is used as a slag basicity adjusting material.

The upper end level of the coke bed is set between the upper tuyere and the lower tuyere, and the room temperature oxygen-enriched air is blown into the coke bed from the lower tuyere. This is for the following reason. That is, the waste in a state after the composite waste is charged and carbonized in the preheating process (hereinafter, referred to as “composite waste”).
Called "waste char". ) Contains a large amount of iron in addition to C. Therefore, C in this waste char
Is burned with oxygen-enriched air, which has a large operational effect. For that purpose, it is necessary to set the upper level of the coke bed between the upper tuyere and the lower tuyere.

The conventional treatment method has a total iron content of about 50%.
<T. Although the composite waste which is Fe is targeted, the treatment method of the present invention is 10% <T. Fe <80%, suitable for treating a wide range of complex waste. In the present invention, the lower limit of the total iron content of the composite waste is 10% <T. Fe was selected because 10% or less is treated as normal combustible waste. The reason for setting Fe <80% is that 80%
The above is a result of adding pre-treatment such as crushing and sorting of composite waste, and is treated as general iron scrap.

The reason why the oxygen-enriched amount of the oxygen-enriched air at room temperature is set to 2% or more is that if it is less than 2%, it is difficult to maintain the temperature of the coke bed under blowing at room temperature, and the waste char after combustion and melting This is because it hinders the temperature rise of slag and metal.

Further, the reason why steam is blown from the upper tuyere is to prevent excess heat by cooling the upper part in the furnace.

Further, the tuyere blowing amount is set so that the upper tuyere blowing amount> the lower tuyere blowing amount is that if the blowing amount of the upper tuyere is increased, the combustion ratio of the waste char increases and the coke ratio decreases. It is because it contributes to.

Further, the use of waste plastic blowing together with oxygen-enriched air at room temperature from the lower tuyere
This is to achieve low coke by using the combustion gas of waste plastic as a heat source.

The reason for controlling the rate of temperature rise of the raw fuel in the furnace by changing the stock level of the charge is the exhaust gas η.
This is for appropriately controlling CO.

Further, large-diameter composite waste which is not dismantled in the center of the furnace, crushed composite waste having a large metal content, and large-diameter coke are crushed to the periphery of the furnace. Among them, those with low metal content, dust agglomerates,
Separating and charging small-diameter coke is performed by performing melting treatment in the central part of the furnace, performing reduction treatment in the peripheral part of the furnace, and further forming a gas flow in the central part of the furnace to form a multi-functional melting furnace. This is to ensure stable operation.

Further, in addition to the composite waste and dust agglomerate as the raw material, iron scrap is also charged, because the excess heat accompanying the combustion of the composite waste is increased by increasing the temperature of the iron scrap.
This is because it is used for melting, and is used as a means for adjusting the production amount and controlling ηCO.

Then, the large-diameter composite waste which is not dismantled in the center of the furnace, the composite waste having a high metal content among the crushed composite waste, iron scrap, and large-diameter coke are crushed into the furnace peripheral portion. Separate charging of complex waste with low metal content, dust agglomerate, and small-diameter coke involves melting at the center of the furnace and reduction at the periphery of the furnace. Further, a gas flow is formed in the central portion of the furnace to stably operate the multifunctional melting furnace.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method for disposing of composite waste according to the present invention will be described below in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. FIG. 1A is a schematic view showing a multifunctional melting furnace used in the method for disposing of composite waste of the present invention. As shown in the figure, a charging device 2 is provided on the furnace top of the multifunctional melting furnace 1. The charging device 2 includes a bucket 3, a bell 4, a movable armor 5, and a charging guide 6, and is configured as a device capable of charging a raw material and a fuel in a radial direction.

An exhaust gas pipe 8 for exhausting countercurrent gas in the furnace is provided above the furnace body 7 of the multifunctional melting furnace 1. An exhaust gas system connected to the exhaust gas pipe 8 is used for a refuse melting furnace.

On the other hand, a tuyere 9 for blowing air to the lower part in the furnace is provided below the furnace body 7. Tuyere 9 is furnace body 7
In the present embodiment, it is formed as a two-stage tuyere of a lower tuyere 9a and an upper tuyere 9b. In addition, these tuyeres 9a and 9b are
Are arranged at appropriate intervals in the circumferential direction.

The blowing conditions are such that oxygen-enriched air having an oxygen enrichment of 8% or more at room temperature is blown from the lower tuyere 9a, and steam is blown from the upper tuyere 9b. In addition, the tuyeres 9a and 9b are configured so that the tuyere diameter and the projecting position in the furnace can be changed in consideration of forming a raceway when a powdery iron source or waste plastic is blown.

In the present embodiment, the multi-stage tuyere 9 provided in the height direction of the side wall of the furnace body 7 is formed as a two-stage tuyere consisting of a lower tuyere 9a and an upper tuyere 9b. At least if the oxygen-enriched air is blown from the tuyere at the bottom,
Three or more tuyeres may be provided. For example, in the case of three stages, forming a raceway at the tuyere located at the middle stage is one means. In this case, the tuyere at the middle stage forms a raceway and blows waste plastic into small diameter coke. The third tuyere is used to maintain the combustion efficiency in the furnace.

Further, the raw material and the fuel can be charged separately in the furnace central portion 11 and the furnace peripheral portion 12.
As described above, the furnace top has the charging device 2 that can be separately charged in the radial direction (FIGS. 1B and 1C).
When charging the complex waste such as waste home appliances into the furnace center 11 without dismantling it, the charging device 2 is retracted, and a charging device (not shown) for large-diameter objects is disposed. is there.

As shown in FIG. 2, the coke bed 13 in the lower part of the furnace is formed by adjusting the height so that the upper end level is located between the lower tuyere 9a and the upper tuyere 9b. Therefore, the oxygen-enriched air is blown into the coke bed 13 from the lower tuyere 9a.

The multi-function melting furnace 1 is a melting furnace for performing an intermediate treatment between a cupola and a refuse melting furnace. In other words, complex wastes such as waste home appliances are carbonized in the heating process after charging the furnace top, and oil such as tar and carbonized gas are scattered from the furnace top. Absent. Also, because of its high iron content, it is not a treatment of combustible waste like a refuse melting furnace. Usually, combustible waste is T. Fe <
10%, not much iron.

Although the refuse melting furnace and the cupola are common in that oxygen-containing gas is blown into a vertical furnace having a coke packed bed, there are the following differences. That is, the refuse melting furnace dry-distills and preheats municipal waste and the like containing a large amount of combustibles, and melts the residue. In addition, the main component is combustion, and a large amount of gas is generated. In addition, dust collection, treatment of harmful gases, exhaust gas purification equipment and methods, dezincing and detinning processes, and solutions for lowering P, S, and mixing with Cu are necessary. is there. Incombustibles are melted and discharged as slag.

The multifunctional melting furnace 1 melts iron scrap, dust and the like to produce hot metal. Mainly iron melting,
Waste plastic is used as fuel. The generated gas is mainly used as fuel gas (partial combustion).

Next, a method for treating a composite waste according to the present invention, which is carried out using the above-mentioned multifunctional melting furnace 1, will be described. The raw materials to be charged from the furnace top are mainly composite waste such as waste home appliances (as they are not dismantled), composite waste after crushing, and dust agglomerate, and mix iron scrap as necessary. . The fuel is mainly coke, and waste plastics are used as needed.

The treatment method of the present invention has a total iron content of 10
% <T. Suitable for treating complex waste with Fe <80%. In the present invention, the lower limit of the total iron content of the composite waste is 10% <T. Fe was selected because 10% or less is treated as normal combustible waste. Fe
The reason why the ratio is set to <80% is that 80% or more has been subjected to a preliminary treatment such as a crushing treatment and a sorting treatment of the composite waste and is generally treated as iron scrap. In general, waste home appliances contain about 37% of iron (T.Fe) and about 37% of waste plastics.
e) is contained 70-80%.

The charging method includes a normal charging method in which the coke is charged to form a coke bed and then the raw fuel is completely mixed or layered, and a charging method in which the raw fuel is radially divided and charged. And how to adopt. As shown in FIG.
Sorting method is as follows: large-diameter composite waste as it is,
The mixed waste with high metal content among the crushed wastes is mixed with large-diameter coke and charged into the center of the furnace, and the crushed composite wastes with low metal content and dust The agglomerate ore is mixed with small-diameter coke and charged into the surrounding area, thereby aiming for operation with high reaction efficiency. The mixed charging of dust agglomerate around the furnace improves the reducibility of the dust agglomerate, and as a result, reduces the amount of slag melt during melting and contributes to avoiding hanging on the shelf Because you do.

Alternatively, as shown in FIG. 4, large-diameter composite waste as it is, crushed composite waste having a large metal content, and iron scrap mixed with large-diameter coke to form a furnace. It is charged into the inner central part, and mixed waste having a small metal content among the crushed wastes is mixed with small-diameter coke and charged into the peripheral part. The purpose of mixing and charging iron scrap in the center of the furnace is to facilitate the control of the height of the coke bed in the center of the furnace, to secure the center gas flow, and to aim for low fuel ratio operation.

Alternatively, as shown in FIG. 5, large-diameter composite waste as it is, crushed composite waste having a large metal content, and iron scrap mixed with large-diameter coke to form a furnace. The mixed waste after crushing, which has a low metal content, and dust agglomerate are mixed with small-diameter coke and charged into the periphery. The mixing and charging of dust agglomerate around the furnace and the charging of iron scrap at the center of the furnace are aimed at the synergistic effect of charging the dust agglomerate and charging iron scrap. . By carrying out such separate charging of the raw material and the fuel, the gas flow in the central part of the furnace is promoted, and the high ηCO condition can be maintained.

The operation of the multifunctional melting furnace is controlled by adjusting the height of the upper end level of the coke bed, the stock level position, the sorting charging method according to the size of the raw fuel, the upper tuyere projecting position, and the like. In the present invention, as described above, the height of the upper end level of the coke bed 13 is set to the lower tuyere 9a and the upper tuyere 9
b. This is for the following reason. That is, the waste char in the state after the composite waste is charged and carbonized in the preheating process contains a large amount of iron in addition to C. Therefore, burning C in the waste char with the oxygen-enriched air has a large operational effect. For this purpose, the upper end level of the coke bed 13 is set between the lower tuyere 9a and the upper tuyere 9b. Because it is necessary to In the coke bed, the combustion reaction of coke and the solution loss reaction after combustion progress, and the reaction speed of both reactions is adjusted by the fuel particle size, gas flow rate, blast temperature and the like.

In particular, the processing method of the present invention is applied to the lower tuyere 9a
At the same time, oxygen-enriched air at room temperature with an oxygen-enriched amount of 2% or more is blown, and steam is blown from the upper tuyere 9b.
The reason why the oxygen-enriched amount of the oxygen-enriched air at room temperature is set to 2% or more is that if it is less than 2%, it is difficult to maintain the coke bed temperature under normal-temperature blast, and the slag after combustion and melting of waste char,
This is because it hinders the temperature rise of the metal. The reason why steam is blown from the upper tuyere is to prevent excess heat by cooling the upper part in the furnace. Further, since the lower tuyere 9a is directed to operation at a low fuel ratio, the main blast is performed without forming a raceway, and the combustion rate is increased to achieve a high ηCO condition. On the other hand, when injecting waste plastic from the lower tuyere 9a, it is necessary to determine the presence or absence of a raceway according to the amount of waste plastic injected, but basically, waste plastic is used as a coke substitute fuel, Aim for low coke.

Next, the outline of the control flow of ηCO in the furnace of the present invention will be described. The control of the present invention is summarized as follows. The average metal content (average M.Fe / T.
Fe). If more efficient operation is to be carried out, separate charging in the radial direction is to be carried out.However, if this charging method is applied, the average metal content of the composite waste to be charged in the central part and peripheral part shall be respectively Ask for.

From the average metal content (average M.Fe / T.Fe) of the charged waste and the C content in the composite waste, an ηCO level range suitable for the operation is specified. When the radial division charging method is applied, an appropriate ηCO is specified for each of the central portion and the peripheral portion.

Since the average gas flow rate in the furnace (Nm / s) is determined by the operating conditions of the melting furnace (standard of tapping amount), the height of the coke bed from the lower tuyere is set according to the particle size of the fuel used.

For the stock level, the target ηCO
And the stock level (the height of the charging surface from the lower tuyere) H (m) corresponding to. When the radial charging method is used, it is preferable to set the stock level separately for the central portion and the peripheral portion.

Regarding the fuel ratio, in addition to the operating conditions including the furnace body heat dissipation (kcal / h) which is a characteristic of the furnace, the target tapping rate (t / d), the type and quality of the composite waste, etc. Once the target ηCO is determined, the fuel ratio (kg / t) level can be determined from the heat / substance balance, and finally, fine adjustment of the lower tuyere airflow and fine adjustment of the stock level are performed. Operate so as to maintain the target ηCO level. When the radial charging method is used, the fuel ratio is set separately for the central portion and the peripheral portion before charging.

Next, it will be described that changing the charging height (stock level) of the charged material composed of the composite waste and the fuel in the melting furnace is effective for the ηCO control. Regarding the stock level, for example, in a cupola operation in which a large-diameter casting coke is used to dissolve iron and casting waste, usually, the height from the lower tuyere to the stock level (H) / furnace diameter (D) ) = 4-5, but there is no study on the stock level of the multifunctional melting furnace using small diameter coke such as coke for blast furnace and using waste plastic as fuel. Therefore, a stock level change test was performed under the condition of using a large amount of composite waste, and the relationship with the exhaust gas ηCO was arranged in FIG.

According to the test results using a multifunctional melting furnace having a hearth diameter D = 1.4 m, by setting H / D ≦ 3, the exhaust gas ηCO can be maintained as high as 50% and the stock level can be increased. By doing so, it has been found that the exhaust gas ηCO can be reduced. This is because, when the stock level is increased, the heat transfer from the gas to the raw fuel becomes better, and the preheating and heating of the fuel proceed from the upper part, so that the solution loss reaction region of the following equation (1) expands to the upper part of the furnace. This suggests that as a result, the consumption of C increases and ηCO decreases. C + CO ₂ = 2CO (1) As described above, the change of the stock level has a role of controlling the rate of temperature rise of the raw fuel in the furnace, and serves as control means of the exhaust gas ηCO.

Next, it will be explained that adjusting the height of the coke bed in the lower part of the furnace of the multi-function melting furnace, and further, that the change of the blown air amount, the tuyere diameter and the tuyere protrusion position are effective for the ηCO control. . FIG. 7 shows an experimental result obtained by an off-line simulator in which the coke bed height from the tuyere and the transition of ηCO at that portion were investigated by changing the coke particle size. According to FIG. 7, oxygen and enriched oxygen in the air blown from the tuyere burn with coke by the reaction of the following formula (2) to generate CO ₂ , and complete combustion occurs at a portion where O ₂ has disappeared. Reach. This portion has the highest gas temperature. Above this portion, the solution reaction of the formula (1), which is an endothermic reaction, proceeds, so that ηCO decreases and the gas temperature also decreases. C + O ₂ → CO ₂・ ・ ・ (2)

When the coke particle size becomes smaller, the combustion speed of the equation (2) becomes faster, and the portion having the highest gas temperature (O ₂ = 0% and ηCO = 100%) becomes closer to the tuyere. Also,
When the blowing rate is increased and the gas flow rate is increased, the flow rate of oxygen blown from the tuyere in the furnace increases, and the contact time with C near the tuyere becomes shorter. Spreads over the furnace. Therefore, when the flow rate is increased with the same coke particle size, as shown in FIG. 8, ηCO in the furnace becomes higher as a whole as compared with the case where the flow rate is low. Protruding the upper tuyere into the furnace or reducing the tuyere diameter and increasing the tuyere wind speed is equivalent to shortening the contact time between the blown oxygen and C, and has the same effect as increasing the furnace flow velocity. There is.
As described above, changing the height of the coke bed in the lower part of the melting furnace, and further, changing the blowing amount, tuyere diameter, and tuyere protrusion position are effective means for controlling the in-furnace ηCO.

Next, the composite waste treatment method employing the radial charging method is effective for the operation stability and low fuel ratio operation, and the efficiency of the waste is independent of the type and particle size of the composite waste. A description will be given of an operation method for directing an efficient operation according to the fact that a good operation can be directed, and according to the properties of the composite waste and the fuel. Regarding the radial charging method, there is an appropriate charging method depending on the type of composite waste. One is an example of increasing the ηCO in the furnace and aiming for efficient operation. Fe / T. One is a fractionation method using Fe, and the other is a fractionation method according to the particle size of the composite waste.

First, it will be described that the fractionation method based on the metal content (M.Fe / T.Fe) of the composite waste contributes to the stabilization of the operation and the efficient operation can be directed.
There are several types of composite waste, Fe / T. When it can be separated by the size of Fe, preferably, a composite waste having a high metal content, for example, a composite waste using a large amount of a metal material, such as some washing machines, is charged into the center of the furnace, and the metal is discharged. A composite waste having a low content, for example, plastic parts / members after disassembly / crushing is charged into the periphery of the furnace. The reason why low-metal-content composite waste is charged around the furnace and high-metal-content composite waste is charged at the center of the furnace is that the height of the coke bed in the center of the furnace is easily controlled. The main objective is to secure the center gas flow and to aim for low fuel ratio operation.

In order to perform this operation, the upper tuyere has a structure in which the tuyere tip protrudes into the furnace from the furnace wall. Ideally, it is provided at the boundary of the part. When importance is placed on making the gas flow the central flow, the peripheral fuel preferably has a small diameter, and the central fuel has a large diameter.

The reason for setting the upper tuyere at the boundary between the center and the peripheral part of the furnace is that the air from the upper tuyere is not used for burning the fuel existing in the peripheral part. This is to make it work for CO gas combustion. The center of the furnace promotes the melting function, so ηCO of the center of the furnace> 90%
It is most efficient if the operation of the furnace is directed at the center of the furnace, and the fuel in the center of the furnace can be reduced to about the carburized content which is the lowest fuel ratio. Therefore, a sudden change in the height of the coke bed can be suppressed, and the coke with the particle size maintained becomes the coke bed, so that a low fuel ratio operation that ensures ventilation and liquid permeability can be performed.

In this operation, the appropriate air flow rate of the upper tuyere is determined by the height of the coke bed. As described above, the coke bed height varies depending on the coke particle size, the gas flow rate in the furnace, and the like. However, when the upper end level of the coke bed is set at the optimum position (ηCO> 90%), the blowing from the upper tuyere It becomes unnecessary. When the ηCO at the upper end level of the coke bed is 90% or less, it is possible to set ηCO> 90% by blowing air from the upper tuyere,
Ideal operation is possible for the furnace center.

Next, a description will be given of the fact that the charging method of mixing the dust agglomerate and the composite waste having a low metal content with the fuel when charging the waste around the furnace is efficient. If an operation with a high ηCO can be aimed at, an operation with a low fuel ratio will be possible. However, an experiment was conducted to reduce dust agglomerate under conditions of ηCO> 30%. No, causing smelting reduction that adversely affects operations in high temperature areas. On the other hand, it was clarified in the results of the offline simulator study that when the dust agglomerate was mixed with coke and charged, the reduction rate was improved by at least 20% as compared with the case where the coke was not mixed with coke.

This indicates that in the operation of charging the dust agglomerate, the charging method of mixing with the fuel (small-diameter coke) reduces the reduction of the dust agglomerate compared to the operation without mixing with the fuel (small-diameter coke). This has the effect of improving the resiliency, and as a result, the amount of slag melt at the time of melting can be reduced, which also contributes to avoiding hanging on a shelf. Further, since the composite waste having a low metal content contains a large amount of C, it can be inserted into the peripheral portion and used as a substitute for coke.

Next, a control method for maintaining the coke bed height will be described. It is difficult to control the height of the coke bed because it is located in the lower center of the furnace, and if the coke ratio is not appropriate, the unreduced FeO melts and reduces at the lower part of the furnace and consumes the coke bed. This is because abnormal wear of the device is caused. In particular, if such abnormal consumption of coke occurs in the lower center portion of the furnace, it will not only hinder the dissolution of iron, but also may cause an operation failure due to solidification of the slag, which is a problem.

Therefore, as described above, at the center of the furnace,
By mainly charging complex waste with a high metal content and mixing iron scraps as necessary, operation that is unlikely to cause smelting reduction in the center of the furnace is performed, and abnormal consumption of the coke bed in the center of the furnace is reduced. Suppress. Also, in order to minimize the solution loss reaction of coke, the fuel to be charged into the center of the furnace is distinguished from the fuel to be charged around the furnace, and large-diameter coke is used. Thereby, abnormal wear of the coke bed in the central part of the furnace can be suppressed, and furthermore, an operation in which the combustion efficiency ηCO in the lower part of the furnace is enhanced can be performed. On the other hand, complex waste with a low metal content is mainly charged in the furnace periphery, and dust agglomerate is mixed and charged as necessary, so that smelting reduction occurs easily in the furnace periphery. .

The installation position of the upper tuyere has an appropriate position depending on the operation specifications such as the coke particle size and the air volume. However, basically, the ηCO level in the lower tuyere is 65% <η.
CO is about 90% or less.

As a simple method of controlling or monitoring the height of the coke bed, there are visual observation at the lower tuyere, judgment by a furnace pressure loss value, and the like. Observation at the lower tuyere can determine that at least the molten portion of the composite waste exists at the upper or lower part of the upper tuyere. Further, by detecting the pressure loss difference between the lower tuyere and the upper tuyere, it is possible to confirm the upper end position of the coke bed. According to the operation example, when the upper end level of the coke bed is below the upper tuyere, a large pressure drop difference between the lower tuyere and the upper tuyere is detected. This is because the presence of the melting portion increases the pressure loss value.

As a method of measuring the height of the coke bed with high accuracy, the height can be determined by measuring the descending behavior of a vertical sonde or iron wires charged from the upper part of the furnace. In the case of a vertical sonde, the temperature in the furnace rises sharply to 1200 ° C. or higher, and when iron wires are used, the point at which the descent speed stops corresponds to the upper end of the coke bed. In the present embodiment, the steam is blown from the upper tuyere 9b to perform the treatment, whereby the furnace top temperature is suppressed to 300 ° C. or less, and efficient operation becomes possible.

The boundary position between the furnace center and the furnace periphery referred to in the present invention moves somewhat in the furnace radial direction depending on the metal content of the composite waste and the coke particle size. The boundary position ri between the central part of the furnace and the peripheral part of the furnace can be obtained by the following equation (3) when the amounts of the composite waste and the fuel to be charged into each part are determined. ri ² = (Wm (c) / ρm (c) + Wc (c) / ρc (c)) / ｛(Wm (c) / ρm (c) + Wc (c) / ρc (c)) + (Wm ( p) / ρm (p) + Wc (p) / ρc (p))｝ (3) where ri: dimensionless boundary radius between the center and the periphery (−) Wm (c): at the center Weight of waste to be charged (kg / charge) Wc (c): Weight of fuel to be charged to the center (kg / charge) Wm (p): Weight of waste to be charged to the periphery (kg / charge) Wc ( p): Weight of fuel charged in the periphery (kg / charge) ρm (c): Bulk density of waste charged in the center (kg /
m ³ ) ρc (c): Bulk density (kg / m ³ ) of fuel charged in the center
) Ρm (p): Bulk density of waste to be charged in the surrounding area (kg /
m ³ ) ρc (p): Bulk density of fuel to be charged in the surrounding area (kg / m ³⁾
)

Note that this ri is represented by a dimensionless radius, and indicates a boundary position when the lowering speed of the charged material in the furnace center portion and the furnace peripheral portion is constant. Various charging methods for adjusting the boundary position indicated by ri can be considered, but even when a bell-type charging device is used, the armor is used, and the central charging and the peripheral charging are performed for each charging charge. By alternately repeating the charging, a partial mixed layer is generated, but a predetermined boundary can be set.

Further, the tuyere blowing amount is set such that the upper tuyere blowing amount> the lower tuyere blowing amount. This is because increasing the amount of air blown from the upper tuyere increases the combustion ratio of the waste char, thereby contributing to a reduction in the coke ratio.

Further, waste plastic is blown from the lower tuyere together with oxygen-enriched air at room temperature. The reason why the waste plastic is injected together is to achieve low coke by using the waste plastic as a fuel and using the combustion gas as a heat source.

As a result of studying the reduction of the amount of coke used, it was found from the following that the position of blowing the waste plastic greatly affects the role played by the waste plastic. FIG. 9 shows ηCO in a coke bed when waste plastic was blown into a normal coke bed.
It is a figure showing an example of a change. There are two types of consumption of C in coke or waste plastic. C + O ₂ → CO ₂ (4) C + CO ₂ → 2 CO (5)

In the reaction of the formula (4), C in coke is effectively used in the exothermic reaction, but in the reaction of the formula (5), C is not effectively used in the endothermic reaction. Thus, although the coke has to be as much as possible (4) reaction of formula, O ₂
When there is no CO2, contact with high temperature CO ₂ causes solution loss of coke by the reaction of equation (5), and coke is wasted.

Since waste plastic has a higher combustion rate than coke, blowing waste plastic into the coke bed lowers the O ₂ disappearing position as compared to the case where no waste plastic is blown. Therefore, even if waste plastic is inadvertently blown into the coke bed under the condition that waste plastic is not blown, coke exists above the O ₂ disappearance position, and the coke consumption of the formula (4) is reduced. Even if it is possible, coke consumption will increase in equation (5),
As a result, the injection of waste plastic cannot contribute to the reduction of coke consumption.

The following two methods are effective for avoiding such a situation and performing coke replacement by blowing waste plastic. That is, the reaction of the formula (5) is not performed in the coke bed, or the C in the coke reacting in the formula (5) is replaced with the C in the waste plastic so that the solution loss of the coke does not occur. It is to be.

In the first method, the upper end level of the coke bed is set to a height at which O ₂ blown from the lower tuyere disappears in consideration of waste plastic, and coke is present in an area where O ₂ does not exist. In this method, waste plastic is blown between the lower tuyere level and the upper end of the coke bed. In this case, the blowing position of the waste plastic may be any position including the lower tuyere as long as it is between the lower tuyere level and the upper end level of the coke bed, and may be one stage or multiple stages.

The second method is to set the upper end level of the coke bed higher than the height at which the O ₂ blown from the lower tuyere disappears in consideration of the waste plastic. with blown between the tuyere level and coke bed upper level, a method of blowing plastic waste for causing solution loss and replaced with coke to nonexistent coke bed upper region of O _2. In this case, the lower waste plastic injection position may be any position including the lower tuyere as long as it is between the lower tuyere level and the O ₂ vanishing point level, and may be one or more stages. Also, the upper part of the waste plastic injection position may be any position as long as it is between the O ₂ vanishing point level and the upper end level of the coke bed, and may be a single stage or a plurality of stages. According to this method, it is possible to increase the amount of waste plastic blown by the amount blown upward.

[0080]

FIG. 10 is a schematic diagram showing the structure of an apparatus for carrying out the method for treating composite waste according to this embodiment. As shown in the figure, in the multi-function melting furnace 1, complex wastes such as waste home appliances are charged by a charging device (not shown), and a dust agglomerate having a carbon content of 3.8% and iron scrap. Is charged. In this embodiment, the composite waste is dismantled and partially treated, or is treated without being dismantled.
The operating conditions of the multifunctional melting furnace 1 are shown in Table 1 below. Slag and metal are discharged from the lower part of the multi-function melting furnace 1, and the exhaust gas is burned and cooled by an exhaust gas treatment device 15 via a cyclone 14 and discharged from a chimney 16.

[0081]

[Table 1] As shown in Table 1, this embodiment shows a case where ηCO is controlled to 45%. The waste home electric appliances are charged by 1000 kg each, and CR represents the coke ratio of each embodiment. In Examples 1-4, 1400 kg of iron scrap was charged together with the waste home appliances, in Examples 5-9, 1000 kg of dust agglomerate was charged, and in Examples 10-13, 500 kg.
And 500 kg of iron scrap were charged together with 1000 kg of dust agglomerate in Examples 14 to 17.

Oxygen-enriched air having an oxygen-enriched amount of 2% or more is blown into the coke bed from the lower tuyere, and steam is blown from the upper tuyere. The tuyere blowing amount is set such that the upper tuyere blowing amount (secondary tuyere blowing amount)> the lower tuyere blowing amount (primary tuyere blowing amount). The amount of steam blown from the upper tuyere was 3 g / Nm in Examples 1-4 and 6-15.
³ , Example 5 was 123 g / Nm ³ , Example 16 was 3
0 g / Nm ³ , and Example 17 is 50 g / Nm ³ .

In the treatment of composite waste, tar and the like are discharged. Therefore, it is preferable to operate the furnace while controlling the temperature of the furnace top gas to 300 ° C. or more as much as possible, and more preferably, to 300 ° C.
Preferably it is in the range of 450 ° C. Therefore, the conditions of Examples 1, 5, 6, 10, and 14 are particularly preferable, and Examples 2, 7, 11, and 15 also exhibit close values and are suitable.

In Examples 1 to 17, during the melting treatment of the composite waste, the dust agglomerate and iron scrap were mixed and charged, and the upper end level of the coke bed was set between the lower tuyere and the upper tuyere. By blowing oxygen-enriched air at room temperature with an oxygen-enriched amount of 8% or more from the lower tuyere into the coke bed and steam from the upper tuyere, the plastic contained in complex waste such as waste home appliances can be used as a fuel component. As a result, stable operation of the multifunctional melting furnace could be performed even if the amount of coke used was reduced.

[0085]

As described above, according to the present invention,
By setting the specific treatment conditions of the multi-function melting furnace, complex waste such as waste home appliances can be safely and efficiently melted without dismantling and separating, and waste plastic processing can be performed. It has an excellent effect that the melting furnace can be operated stably by reducing the amount used.

[Brief description of the drawings]

FIG. 1 is a multifunctional melting furnace used in the method for disposing of composite waste according to the present invention, wherein (a) is a schematic diagram showing the entire configuration,
(B) is a schematic diagram showing a state of charging the charging device into the furnace center, and (c) is a schematic diagram showing a state of charging the charging device around the furnace.

FIG. 2 is a schematic diagram showing an upper end level of a coke bed.

FIG. 3 is a schematic view showing a charging state in a furnace in a radial direction when a composite waste and dust agglomerate are employed as raw materials.

FIG. 4 is a schematic view showing a charging state in a furnace in a radial direction when a composite waste and iron scrap are used as raw materials.

FIG. 5 is a schematic diagram showing a charging state in a furnace in a radial direction in a case where composite waste, dust agglomerate, and iron scrap are used as raw materials.

FIG. 6: Exhaust gas ηCO in stock level change test
FIG. 4 is an explanatory diagram showing a relationship with the above.

FIG. 7 is an explanatory diagram showing an experimental result of a transition of coke bed height and ηCO by an offline simulator.

FIG. 8 shows the η when the flow velocity is changed at the same coke particle size.
It is explanatory drawing which shows the change of CO.

FIG. 9 is an explanatory diagram showing a change in ηCO when waste plastic is blown.

FIG. 10 is a schematic diagram showing the configuration of an apparatus for performing the method for treating composite waste according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multifunctional melting furnace 2 Charging device 3 Bucket 4 Bell 5 Movable armor 6 Charging guide 7 Furnace body 8 Exhaust gas pipe 9 Tuyere 9a Lower tuyere 9b Upper tuyere 11 Furnace center part 12 Furnace peripheral part 14 Cyclone 15 Exhaust gas treatment Device 16 chimney

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22B 7/00 B09B 3/00 303E (72) Inventor Fura Masuda 20-1 Shintomi, Futtsu-shi, Chiba Prefecture Made in New Japan 4D004 AA07 AA22 AB03 BA03 CA04 CA24 CA29 CA37 CA42 CB13 CB50 CC02 CC11 DA03 DA10 4F301 AB02 BA17 BA21 BE08 BE21 BE31 BF12 BF31 4K001 AA02 AA09 AA10 BA22 BA24 DA01 GB01 GA14 HA10 HA12 JA01 4K012 CB02 CB05 CB07 4K045 AA01 AA02 BA02 BA03 BA10 DA02 DA04 DA09 GB07 GB10 GB12 GB13 GB20 GC01

Claims (10)

[Claims] 1. A multifunctional melting furnace having a multi-stage tuyere is charged with a composite waste containing at least metal and plastic together with coke, and dried, pyrolyzed, burned,
When melting and processing the composite waste, the composite waste is charged as a raw material together with dust agglomerate ore and / or iron scrap, and the upper level of the coke bed is placed between the upper and lower tuyeres. A method for treating a complex waste, comprising setting and blowing oxygen-enriched air at normal temperature from a lower tuyere to a coke bed. 2. The composite waste has a total iron content of 10% or less.
The method according to claim 1, wherein Total Fe <80%. 3. The oxygen-enriched amount of oxygen-enriched air at room temperature is 2%.
The method for treating a composite waste according to claim 1 or 2, wherein: 4. The method for treating a composite waste according to claim 1, wherein steam is blown in from an upper tuyere to cool an upper part in the furnace. 5. The method for treating composite waste according to claim 1, wherein the tuyere blowing amount is set such that the upper tuyere blowing amount> the lower tuyere blowing amount. 6. The method for treating composite waste according to claim 1, wherein waste plastic is blown from the lower tuyere together with oxygen-enriched air at room temperature. 7. The method for treating a composite waste according to claim 1, wherein the stock raising level of the charge is changed to control a heating rate of the raw fuel in the furnace. . 8. A large-diameter composite waste which is not dismantled in the center of the furnace, and a composite waste having a high metal content among crushed composite wastes are mixed and charged with a large-diameter coke and charged around the furnace. The composite waste according to any one of claims 1 to 7, wherein the mixed waste having a small metal content and the dust agglomerate mixed with the small-diameter coke are charged after the crushing. Processing method. 9. A large-diameter composite waste that is not dismantled at the center of the furnace, a composite waste having a high metal content among crushed composite wastes, and iron scrap mixed with large-diameter coke and charged. The method for treating a composite waste according to any one of claims 1 to 7, wherein, of the composite waste after the crushing, one having a small metal content is mixed with small-diameter coke and charged in the peripheral portion. . 10. A large-diameter composite waste that is not dismantled in the center of the furnace, a composite waste having a high metal content among crushed composite wastes, and iron scrap mixed with large-diameter coke and charged. The composite waste according to any one of claims 1 to 7, wherein the waste having a low metal content and dust agglomerate mixed with small-diameter coke are charged into the peripheral portion after the crushing. How to treat complex waste.