JP3914677B2 - Operation method of dust reduction furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention controls the upper level of a coke bed by blowing waste plastic from a primary tuyere when melting and reducing iron scraps and dust agglomerates in a dust reduction treatment furnace having a multistage blow tuyere. In addition, the present invention relates to a method for operating a dust reduction treatment furnace in which waste plastic is blown from a secondary tuyere and processed.
[0002]
[Prior art]
In general, waste is separated and collected into combustibles and noncombustibles, but incombustibles actually include combustible plastic products. Therefore, the waste plastic is collected as an incombustible material and then landfilled at the final disposal site. Disposable thinking is still established as the aftermath of the booming economy, but with the increase in the amount of waste in recent years, the disposal method of waste plastics has become a problem.
[0003]
In addition, waste home appliances such as used washing machines, refrigerators, and air conditioners are composite waste containing plastic, rubber, and the like in addition to metal. Conventionally, such composite waste has been disassembled and crushed into small pieces and landfilled at the final disposal site, despite containing useful metal materials such as iron, aluminum and copper.
[0004]
However, due to the shortage of final disposal sites and the enactment of new recycling laws, a recycling demonstration plant has been constructed, and attempts have been made to separate the composite waste and recover useful metal materials. In other words, composite waste is classified according to the type of product such as washing machines, refrigerators, etc., after extracting dangerous substances such as cooling media and lubricating oil, it is disassembled for each component and member, and the dismantled piece is made of metal or plastic Each raw material is sorted and processed according to the raw material. For example, the separated metal scrap is charged into a melting furnace together with coke and melted, and the waste plastic after separation is crushed and landfilled.
[0005]
Such a separation processing method is an effective means in that useful metal materials can be collected and the amount of crushed pieces to be landfilled can be reduced. However, waste plastic is still being landfilled.
Therefore, attempts have been made to insert waste plastic into a shaft furnace such as a blast furnace or cupola and incinerate it.
[0006]
[Problems to be solved by the invention]
In such a shaft furnace, it is possible to safely process waste plastic without generating harmful substances. However, the blast furnace and cupola tuyere are usually configured as a single stage, and waste plastic is blown into a melting furnace having two or more stages, such as a dust reduction furnace, to control the reaction in the furnace. The specific conditions for doing so have not been elucidated at all.
[0007]
In view of the above problems, the object of the present invention is to set specific conditions for injecting waste plastic into a dust reduction treatment furnace having a multistage blower tuyere and to change the upper end level of the coke bed located in the lower part of the furnace. It is an object of the present invention to provide a method for operating a dust reduction treatment furnace capable of efficiently incinerating waste plastics while maintaining stable operation of the dust reduction treatment furnace.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the method of operating the dust reduction treatment furnace of the present invention is a melting / reduction treatment by charging iron dust, dust agglomerate and coke into a dust reduction treatment furnace having a multi-stage ventilation tuyere. When doing so, blow air that does not form a raceway from the primary tuyere to the coke bed, blow in granular waste plastic, and control so that the upper end level of the coke bed does not change. Blowing without forming a raceway is performed on the packed bed at the top of the bed, and granular waste plastic is blown in for treatment.
[0009]
In the operation method of the dust reduction furnace, it is preferable to blow in the granular waste plastic from the primary tuyere under normal temperature oxygen-enriched air. It is preferable that the oxygen enrichment amount of this room temperature ventilation is 2% or more.
[0010]
Moreover, it is preferable to blow and process a granular waste plastic from the secondary tuyere under hot air blowing at 700 degrees C or less.
[0011]
Furthermore, it is preferable to adjust the amount of waste plastic blown from the primary tuyere so that the lowering speed of the raw fuel becomes constant.
[0012]
And it is preferable to set the waste plastic blowing position from the secondary tuyere in the area above the coke bed.
[0013]
In addition, the amount of waste plastic blown is 0.2 kg / Nm.^ThreeIt is preferable to set the following.
[0014]
Furthermore, it is preferable that iron scrap is mixed with large-diameter coke and charged into the furnace center, and dust agglomerate is mixed with small-diameter coke and charged into the furnace periphery.
[0015]
According to the present invention, in a dust reduction treatment furnace having a multi-stage ventilation tuyere, granular waste plastic is blown from the primary tuyere into the coke bed under a normal temperature oxygen-enriched blast. On the other hand, granular waste plastic is blown into the packed bed above the coke bed from the secondary tuyere under hot air. At that time, the reason why the raceway is not formed is that when the raceway space is formed, the combustion of the coke and the solution reaction proceed, and the efficiency of the dust reduction treatment furnace decreases.
[0016]
By blowing waste plastic from the primary tuyere into the coke bed, it is possible to control so that the upper end level of the coke bed does not change. The reason is CO in the coke bed₂In order to maintain a constant amount of reaction (solution loss reaction) between the coke and the coke.₂This is for the purpose of adjusting the amount of solution loss reaction that causes the fluctuation of the lowering speed of the raw fuel by blowing the waste plastic.
On the other hand, the waste plastic is efficiently incinerated by blowing the waste plastic from the secondary tuyere into the packed bed above the coke bed.
However, since the combustion product gas is large, the gas temperature is lowered, and in the process of metal dissolution such as iron scrap dissolution / dust reduction, it becomes a lack of heat. In order to make up for this lack of heat, normal temperature oxygen-enriched air is blown from the primary tuyere and hot air is blown at 700 ° C. or less from the secondary tuyere.
[0017]
The amount of oxygen enrichment of room temperature air blown from the primary tuyere is 2% or more. If it is 2% or less, the amount of gas in the furnace increases as the waste plastic is blown, resulting in a decrease in gas temperature and slag. This is because it will hinder the dissolution of metal.
[0018]
On the other hand, the temperature of the hot air blowing from the secondary tuyere was set to 700 ° C. or lower because when the blowing temperature exceeded 700 ° C., the combustion reaction and the solution loss reaction of coke were promoted and the coke ratio was not necessarily reduced. is there.
[0019]
Further, the amount of waste plastic blown from the primary tuyere is adjusted so that the lowering speed of the raw fuel is constant. In this way, the amount of waste plastic blown in based on the descent speed of the raw fuel is adjusted by the CO in the coke bed.₂In order to maintain a constant amount of reaction (solution loss reaction) between the coke and the coke.₂This is for the purpose of adjusting the amount of solution loss reaction that causes fluctuations in the lowering speed of the raw fuel by blowing waste plastic.
[0020]
Furthermore, since the reaction speed is faster than that of coke, the waste plastic blowing position from the secondary tuyere is set in the upper area of the coke bed.₂This is because the coke consumption is suppressed.
[0021]
And the amount of waste plastic blown is 0.2kg / Nm.^ThreeThe upper limit for the amount of waste plastic blown is 0.2 kg / Nm.^ThreeThis is because the waste plastic that exceeds the upper limit amount does not burn, so that it does not replace fuel with coke and is not used effectively.
[0022]
In addition, iron scrap and large diameter coke in the furnace center, and dust agglomerate and small diameter coke in the furnace periphery are charged separately in the center of the furnace. This is because the dust agglomerate is reduced in the periphery of the furnace, and a gas flow is formed in the center of the furnace for stable operation of the dust reduction furnace.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the embodiment in the operation method of the dust reduction processing furnace of the present invention is explained in full detail based on an accompanying drawing, the present invention is not limited to the following embodiment.
[0024]
Fig.1 (a) is the schematic which shows the dust reduction processing furnace used for the operating method of the dust reduction processing furnace of this invention. As shown in the figure, a charging device 2 is provided at the top of the dust reduction treatment 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 the raw material and fuel in a radial direction.
[0025]
An exhaust gas pipe 8 for exhausting counterflow gas in the furnace is provided on the upper part of the furnace body 7 of the dust reduction treatment furnace 1. As the exhaust gas system connected to the exhaust gas pipe 8, for example, a waste melting furnace is used.
On the other hand, a tuyere 9 for blowing air to the lower part in the furnace is provided at the lower part of the furnace body 7. The tuyere 9 is provided in multiple stages in the side wall height direction of the furnace body 7, and in FIG. 1 (a), there are a lower tuyere (primary tuyere) 9a and an upper tuyere (secondary tuyere) 9b. It is formed as a two-stage tuyere. Further, a plurality of these tuyere 9a, 9b are arranged at appropriate intervals in the circumferential direction of the furnace body 7.
[0026]
The air blowing condition is that the primary tuyere 9a is the main tuyere, oxygen-enriched air is blown from the main tuyere 9a, and the secondary tuyere 9b is hot air blown for observation of the upper end level of the coke bed. use. When performing oxygen-enriched ventilation at room temperature from the main tuyere 9a, the oxygen-enriched amount is set to 2% or more and the air is blown. On the other hand, when hot air is blown from the secondary tuyere 9b, it is blown at a temperature of 700 ° C. or lower. Further, the tuyere 9a, 9b is set so as not to form a raceway even when a powdered iron source or waste plastic is blown, and is configured to be able to change the tuyere diameter and the position of protrusion in the furnace.
[0027]
In the present embodiment, the multi-stage tuyere 9 provided in the side wall height direction of the furnace body 7 has two stages, a lower tuyere (primary tuyere) 9a and an upper tuyere (secondary tuyere) 9b. Although formed as tuyere, three or more tuyere may be provided. For example, in the case of three stages, the tuyere located on the side of the coke bed is the main tuyere, and waste plastic is blown in while main air is blown from the main tuyere to maintain the coke bed upper end level and combustion efficiency. At the same time, waste plastic is blown from the tuyere located above the coke bed.
[0028]
In addition, the raw material and fuel can be charged separately in the furnace center portion 11 and the furnace peripheral portion 12, and as described above, the charging that can be charged in the radial direction at the furnace top portion is possible. The apparatus 2 is included (FIGS. 1B and 1C).
[0029]
As shown in FIG. 2, the height of the coke bed 13 in the lower part of the furnace is adjusted by blowing waste plastic from the primary tuyere 9a so that the upper end level is substantially the same level as the secondary tuyere 9b. Formed. That is, with the primary tuyere 9a as the main tuyere, waste plastic is blown from the main tuyere 9a into the coke bed 13 under normal temperature oxygen-enriched blast, and from the secondary tuyere 9b to the upper part of the coke bed. Waste plastic is blown into the packed bed under hot air.
[0030]
Thus, unlike the shaft furnace such as a blast furnace or a cupola, the dust reduction treatment furnace 1 has a multistage blower tuyere and performs a melting treatment of iron scrap and a reduction treatment of dust agglomerated ore. It is a melting furnace.
[0031]
Next, an operation method of the dust reduction treatment furnace of the present invention that is performed using the dust reduction treatment furnace 1 will be described.
The raw materials charged from the top of the furnace are mainly iron scraps and dust agglomerates, and the fuel is mainly coke, and granular waste plastic is blown from the primary tuyere (main tuyere) 9a and secondary tuyere 9b. Process with.
[0032]
The charging method includes a normal charging method in which the raw fuel is completely mixed or layered after charging the coke to form a coke bed, and a method in which the raw fuel is divided in the radial direction and charged. Is adopted.
[0033]
As shown in FIG. 3, the sorting and charging method mixes iron scrap and large-diameter coke and charges them in the center of the furnace, mixes with dust agglomerate and small-diameter coke, and mixes them in the periphery of the furnace. By charging, it aims to operate with high reaction efficiency. Iron scrap is charged in the center of the furnace and dust agglomerate is charged in the periphery of the furnace. The iron scrap is dissolved in the center of the furnace and the dust agglomerate is reduced in the periphery of the furnace. This is to promote gas flow in the center of the furnace and continue high ηCO conditions.
[0034]
The operation of the dust reduction furnace is to maintain the coke bed top level at a constant level, according to the charging method according to the size of the raw fuel, air blowing conditions of the main tuyere (air blowing temperature, oxygen enrichment, feather It is controlled by the amount of waste plastic blown in based on the lowering speed of the raw fuel.
In the coke bed, the combustion reaction of coke and waste plastic and the solution loss reaction after combustion proceed. The reaction rate of both reactions is adjusted by the fuel particle size, gas flow rate, blowing temperature, and the like.
[0035]
In the present invention, in the dust reduction treatment furnace 1 having a multistage blower tuyere, the primary tuyere (main tuyere) 9a is passed from the primary tuyere 9a to the coke bed 13 without forming a raceway under a normal temperature oxygen-enriched blow. Of waste plastic. On the other hand, granular waste plastic is blown into the packed bed above the coke bed from the secondary tuyere without forming a raceway under hot air. The reason why the raceway is not formed in this way is that when the raceway space is formed, the combustion of the coke and the solution reaction proceed, and the efficiency of the dust reduction treatment furnace decreases.
[0036]
By blowing waste plastic directly into the coke bed, it is possible to maintain the upper end level of the coke bed 13 so that the waste plastic blown from the main tuyere has priority over coke. Oxygen and CO₂This is because the coke consumption in the coke bed can be suppressed, and the coke consumption in the coke bed can be controlled by adjusting the particle size and amount of the waste plastic to be blown.
[0037]
On the other hand, the waste plastic is efficiently incinerated by blowing the waste plastic from the secondary tuyere into the packed bed above the coke bed.
[0038]
However, since there are many combustion product gases, gas temperature falls and it becomes a heat shortage in the process which melt | dissolves metals like iron scrap dissolution / dust reduction. In order to make up for this lack of heat, in the present invention, air blowing at room temperature enriched with 2% or more oxygen from the primary tuyere and hot air blowing at 700 ° C. or less from the secondary tuyere are performed.
[0039]
When performing oxygen-enriched air blowing from the primary tuyere 9a at room temperature, the oxygen enrichment amount is set to 2% or more. If the oxygen enrichment amount is 2% or less, the amount of gas in the furnace increases as waste plastic is blown. This is because the gas temperature is lowered and hinders dissolution of slag and metal.
[0040]
On the other hand, the temperature of the hot air blowing from the secondary tuyere 9b is set to 700 ° C. or less because when the blowing temperature exceeds 700 ° C., the fuel reaction and the solution loss reaction of coke are promoted and the coke ratio is not necessarily reduced. It is.
[0041]
In the present embodiment, the properties of the waste plastic are not limited. However, when the waste plastic is blown from the primary tuyere 9a under normal temperature oxygen-enriched air, for example, waste plastic having a small particle size of 1 mm or less is used. To do. On the other hand, when waste plastic is blown in while blowing hot air from the secondary tuyere 9b, waste plastic having a large particle size of, for example, several millimeters can be used.
[0042]
Further, the amount of waste plastic blown from the primary tuyere 9a is adjusted so that the lowering speed of the raw fuel becomes constant. In this way, the amount of waste plastic blown in based on the descent speed of the raw fuel is adjusted by the CO in the coke bed.₂In order to maintain a constant amount of reaction (solution loss reaction) between the coke and the coke.₂This is for the purpose of adjusting the amount of solution loss reaction that causes the fluctuation of the lowering speed of the raw fuel by blowing the waste plastic.
[0043]
Furthermore, since the reaction speed is faster than that of coke, the waste plastic blowing position from the secondary tuyere 9b is set in the region above the coke bed.₂This is because the coke consumption can be suppressed.
[0044]
The amount of waste plastic blown is 0.2 kg / Nm.^ThreeSet as follows. The upper limit of the blowing rate is 0.2kg / Nm^ThreeThe waste plastic blowing rate is set to 0.2kg / Nm^ThreeThis is because the waste plastic that exceeds the upper limit amount does not burn, so that it does not replace fuel with coke and is not used effectively.
[0045]
Next, the treatment method adopting the radial sorting and charging method is effective for operation stability and low fuel ratio operation, and can be directed to efficient operation regardless of the type and particle size of the raw material. An operation method for directing efficient operation according to the properties of the fuel will be described.
There is an appropriate charging method depending on the type of raw material for the radial sorting charging method. One is an example of increasing the ηCO in the furnace and aiming for efficient operation, which is a fractionation method based on the metallization rate (M.Fe / T.Fe) of the raw material, and one depending on the particle size of the raw material This is a separate method.
[0046]
First, it will be explained that the fractionation method based on the metallization rate (M.Fe / T.Fe) of the raw material contributes to the stabilization of the operation, and the efficient operation can be directed.
There are several types of raw materials. Fe / T. When separation is possible according to the size of Fe, it is preferable that raw materials with a high metallization rate, such as iron scrap, be charged into the furnace center, and raw materials with a low metallization rate, such as dust agglomerates, are loaded in the periphery of the furnace. Enter. The reason why the raw material with a low metallization rate is charged in the periphery of the furnace and the raw material with a high metallization rate is charged in the center of the furnace is to make it easy to control the height of the coke bed in the center of the furnace. This is to ensure the flow and to aim for low fuel ratio operation.
[0047]
When directing this operation, the main tuyere has a structure in which the tip of the tuyere protrudes into the furnace rather than the furnace wall. Basically, the tip of the main tuyere is located at the boundary between the furnace center and the furnace periphery. Ideally provided in Further, considering the gas flow as the central flow, the peripheral fuel preferably has a small diameter, and the central fuel preferably has a large diameter.
[0048]
The reason why the main tuyere is set at the boundary between the central part and the peripheral part of the furnace is that the air blown from the main tuyere is not used for the combustion of the fuel existing in the peripheral part. This is to make it work. Since the furnace center promotes the melting function, it is most efficient if the operation is directed to ηCO> 90% of the furnace center, and the fuel in the furnace center can be about carburized, which is the lowest fuel ratio. . Therefore, a rapid change in the coke bed height can be suppressed, and the coke having a maintained particle size becomes a coke bed, so that a low fuel ratio operation that ensures air permeability and liquid permeability becomes possible.
[0049]
In this operation, the appropriate air volume of the main tuyere is determined by the coke bed height. When ηCO at the upper end level of the coke bed is 60% or more, it is possible to set ηCO> 90% by blowing air from the main tuyere, and ideal operation is possible with respect to the furnace center.
[0050]
Next, it will be explained that when a raw material having a low metallization rate is charged into the periphery of the furnace, a charging method mixed with fuel is efficient.
If the operation with a high ηCO can be directed, an operation with a low fuel ratio can be realized. However, an experiment was conducted to reduce a raw material with a low metalization rate under the condition of ηCO> 30%. Does not proceed and causes smelting reduction which adversely affects the operation at high temperature. On the other hand, even if the raw material with a low metalization rate is mixed with coke and charged, compared with the case where it is not mixed with coke, the reduction rate improvement effect of at least 20% is clear from the examination results of the offline simulator. became.
[0051]
This means that in operations that charge raw materials with a low metalization rate, the charging method that mixes with fuel (small-diameter coke) improves the reduction of composite waste compared to the operation that does not mix with fuel (small-diameter coke). As a result, it is shown that the amount of slag melt at the time of melting can be reduced, and this contributes to avoiding shelf hanging.
[0052]
Next, in addition to the injection of waste plastic from the main tuyere into the coke bed, the point that the section charging method in the furnace radial direction contributes to maintaining the coke bed height will be described.
It is difficult to control the height of the coke bed. This is at the lower center of the furnace. This is because the abnormal consumption of this is caused. In particular, when such an abnormal consumption of coke occurs in the lower center of the furnace, it becomes a problem because it interferes with melting of iron and may become inoperable due to solidification of slag.
[0053]
Therefore, as described above, the furnace center is mainly charged with raw materials with a high metallization rate, for example, iron scrap, so that it is difficult to cause smelting reduction in the furnace center. Reduce abnormal consumption. Also, in order to suppress the coke solution loss reaction as much as possible, the fuel charged in the furnace center is distinguished from the fuel charged in the furnace periphery, and large-diameter coke is used. As a result, abnormal wear of the coke bed at the center of the furnace can be suppressed, and further, an operation with an increased combustion efficiency ηCO at the lower part of the furnace becomes possible.
On the other hand, a raw material having a low metallization rate, for example, a dust agglomerate, is mainly charged in the periphery of the furnace so that the operation easily causes smelting reduction in the periphery of the furnace.
[0054]
The installation position of the upper tuyere has an appropriate position depending on the operation specifications such as the coke granularity and the air flow rate, but basically, the ηCO level at the main tuyere is ηCO> 60% as a guide. .
[0055]
Simple methods for controlling or monitoring the coke bed height include visual observation at the upper tuyere and determination based on the pressure loss value in the furnace. The observation at the upper tuyere portion can determine that at least the melting portion of the raw material exists in either the upper part or the lower part of the upper tuyere. In addition, the upper end position of the coke bed can be confirmed by detecting the pressure loss difference between the lower tuyere and the upper tuyere. According to the operation example, when the upper end level of the coke bed is below the upper tuyere, the pressure loss difference between the lower tuyere and the upper tuyere is detected greatly. This is because the presence of the melted portion increases the pressure loss value.
[0056]
Moreover, as a method of measuring the coke bed height with high accuracy, it 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 suddenly rises and corresponds to a portion where the temperature is 1200 ° C. or higher. When iron wires are used, the point at which the descent speed stops corresponds to the upper end of the coke bed.
[0057]
In the present invention, the boundary position between the furnace center and the furnace periphery moves somewhat in the furnace radial direction depending on the metallization rate of the raw material and the coke grain size.
The boundary position ri between the furnace central part and the furnace peripheral part can be obtained by the following equation (1) if the amount of raw material and fuel charged in each part is determined.
ri²= (Wm (c) / ρm (c) + Wc (c) / ρc (c)) / {(Wm (c) / ρm (c) + Wc (c) / ρc (c)) + (Wm (p) / ρm (p) + Wc (p) / ρc (p))} (1)
Ri: dimensionless boundary radius (−) between the central portion and the peripheral portion
Wm (c): Weight of raw material charged in the center (kg / charge)
Wc (c): Fuel weight charged in the center (kg / charge)
Wm (p): Raw material weight (kg / charge) charged to the periphery
Wc (p): Weight of fuel to be charged in the surrounding area (kg / charge)
ρm (c): Bulk density of raw material charged in the center (kg / m^Three)
ρc (c): Bulk density of fuel to be charged in the center (kg / m^Three )
ρm (p): Bulk density of raw material to be charged in the peripheral part (kg / m^Three )
ρc (p): Bulk density of fuel to be charged in the peripheral part (kg / m^Three )
[0058]
In addition, this ri is represented by a dimensionless radius, and indicates the boundary position when the descending speed of the charge in the furnace center and the furnace periphery is constant. Various charging methods for adjusting the boundary position indicated by ri can be considered. Even when a bell-type charging device is used, an armor is used, and a central charging and a peripheral charging are performed for each charging charge. Although a mixed layer is generated by charging repeatedly and alternately, a predetermined boundary can be set.
[0059]
Figure 4 shows the CO in the coke bed when waste plastic is blown into the normal coke bed.₂, CO and O₂ It is a figure which shows the change of.
There are two forms of C consumption in coke or C in waste plastic:
C + O₂  → CO₂     ... (2)
C + CO₂  → 2CO (3)
[0060]
In FIG. 4, CO₂ As shown in the concentration curve, as the air blower tuyere moves upward from the coke bed, CO 2 is reacted by the reaction of equation (2).₂ Concentration increases, O₂ Is consumed and decreased. And O₂ Above the position where the disappearance of CO2 occurs due to the reaction of formula (3).₂ The concentration decreases and the CO concentration begins to increase.
[0061]
In the reaction of the formula (2), C in the coke is effectively used in an exothermic reaction, but in the reaction of the formula (3), C is not effectively used in an endothermic reaction. Therefore, it is necessary to cause the coke to react as much as (2).₂ High temperature CO₂When contact is made, coke solution loss occurs due to the reaction of equation (3), and coke is wasted.
[0062]
Waste plastic has a higher burning rate than coke. Therefore, when waste plastic is blown into the coke bed, it is O.₂ The disappearance position of will go down. Therefore, even if waste plastic is blown into the coke bed under the condition that waste plastic is not blown, O₂ Coke is present above the disappearance position of, and even though the coke consumption in equation (2) can be reduced, the coke consumption in equation (3) increases, and as a result, waste plastic blowing is associated with coke consumption. It becomes impossible to contribute to the reduction of.
[0063]
The following two methods are effective in avoiding this situation and allowing coke substitution by waste plastic blowing. That is, the reaction of the formula (3) is not performed in the coke bed, or the Coke in the coke reacted in the formula (3) is replaced with C in the waste plastic so as not to cause a coke solution loss. It is to be.
[0064]
The first method is O blown from the main tuyere₂ Set the upper level of the coke bed to the height at which the waste plastics are added and disappear.₂ In this method, waste plastic is blown between the main tuyere level and the coke bed upper end level so that coke does not exist in the area where there is no waste. Corresponding to In this case, the waste plastic blowing position may be an arbitrary position including the main tuyere as long as it is between the main tuyere level and the coke bed upper end level.
[0065]
The second method is O blown from the main tuyere₂ In this case, the upper level of the coke bed is set higher than the height at which the waste plastic is taken into account. In this case, the waste plastic is blown between the main tuyere level and the upper level of the coke bed, and O₂ In this method, waste plastic is blown into the upper area of the coke bed where no coke exists to cause solution loss instead of coke. In this case, the waste plastic blowing position at the bottom is the main tuyere level and O₂ As long as it is between the vanishing point level, it may be at an arbitrary position including the main tuyere, and may be one stage or a plurality of stages. In addition, the waste plastic blowing position at the top is also O₂ As long as it is between the vanishing point level and the coke bed upper end level, it may be at an arbitrary position, and may be one stage or a plurality of stages. According to this method, the amount of waste plastic blown can be increased by the amount blown into the upper part.
[0066]
【Example】
Hereinafter, although the Example in the operating method of the dust reduction processing furnace of this invention is described, this invention is not limited to a following example.
Aiming at maintaining the coke bed top level of the dust reduction furnace, reducing the coke ratio, and treating waste plastics, air is blown at room temperature without forming the raceway from the primary tuyere, and the raceway from the secondary tuyere. An experiment of blowing waste plastic (hot model experiment) into the coke bed and the packed bed above the coke bed was performed under the blowing condition of blowing hot air without forming.
In addition, the combustibility of waste plastic was investigated from the dust properties collected at each part of the coke bed and the packed bed above the coke bed, and the combustion behavior and reaction behavior of the waste plastic were investigated from the coke consumption rate (descent behavior).
[0067]
Waste plastics include polyethylene particles (up to 1.0 mm, typical particle size of 680 μm, bulk density of 0.408 t / m.^Three)It was used. The composition of the polyethylene particles is C: 85.2%, H: 14.3%, O: <0.1%, and the calorific value is 10,000 cal. The air from the primary tuyere was an oxygen-enriched air at normal temperature, and the oxygen enrichment amount was 4%. The air from the secondary tuyere was hot air, and the temperature was 500 ° C. The amount of waste plastic blown is 0.15 kg / Nm.^ThreeIt was.
[0068]
As a result, first of all, an example during the test operation is shown in FIG. The test furnace is provided with peep holes at 70 cm, 80 cm (secondary tuyere), and 90 cm on the main tuyere (primary tuyere). The melting part) can be observed directly. In FIG. 5, the waste plastic from the main tuyere is constantly 0.15 kg / Nm.^ThreeThe coke bed top position began to drop 5 hours after the start of the experiment, but the amount of waste plastic blown was 0.16 kg / Nm.^ThreeIt is an example of an experiment which shows a situation where the coke bed upper end position is returned to the original level by increasing it. From the top of the furnace, no waste plastic particulates are seen, and CH_FourSince there is no gas, it is confirmed that the waste plastic blown from the tuyere is consumed in the furnace. In addition, by blowing waste plastic, the coke ratio is reduced, and it is effectively used as an alternative fuel for coke.
[0069]
Second, when polyethylene is blown from the secondary tuyere, ηCO (= CO₂ / (CO + CO₂ ) Was found to be low. This suggests that under hot air blowing conditions, combustibility is better than coke and the solution loss reaction is faster. That is, preferential consumption of polyethylene by blast oxygen was confirmed.
[0070]
Third, CH_FourAccording to the analysis, as shown in FIG.₂H_FourDisappearance and CH_FourSince the decrease in the amount of white matter and the whitening of the dust have progressed, it is determined that the combustion decomposition of polyethylene is almost completed at this site.
[0071]
Fourth, as shown in FIG. 7, when polyethylene was blown from the secondary tuyere, it was confirmed that the descent of coke was stagnant (no change for at least 30 minutes) in the region above the coke bed. That is, it was confirmed that the coke combustion reaction was extremely small up to the region above the coke bed, and that polyethylene was burning and reacting.
[0072]
From the above experimental results, it was confirmed that blowing plastic waste into the coke bed from the primary tuyere under normal temperature oxygen-enriched ventilation is effective for stable operation without changing the upper level of the coke bed. In addition, blowing waste plastic into the packed bed at the top of the coke bed under hot air blown from the secondary tuyere is effective for the treatment of waste plastic, and stable operation can be achieved by blowing waste plastic into the area above the coke bed. It was confirmed that it was possible.
[0073]
【The invention's effect】
As described above, according to the present invention, by setting specific conditions when blowing waste plastic into a dust reduction treatment furnace having a multistage blowing tuyere, by blowing waste plastic from the primary tuyere, While maintaining stable operation of the dust reduction furnace, it can be controlled so that the upper level of the coke bed located in the lower part of the furnace does not change, and waste plastic is efficiently injected by blowing waste plastic from the secondary tuyere. It exhibits an excellent effect that it can be incinerated.
[Brief description of the drawings]
FIG. 1 is a dust reduction treatment furnace used in the method of operating a dust reduction treatment furnace according to the present invention, wherein (a) is a schematic diagram showing the overall configuration, and (b) is a diagram showing how the charging device is attached to the furnace center. The schematic which shows a charging condition, (c) is the schematic which shows the charging condition to the furnace peripheral part of the charging device.
FIG. 2 is a schematic view showing an upper end level of a coke bed and a waste plastic blowing position in a two-stage tuyere dust reduction treatment furnace.
FIG. 3 is a schematic view showing the state of sorting and charging in the furnace radial direction.
[Fig. 4] CO in the furnace₂It is explanatory drawing which shows a density | concentration curve.
FIG. 5 is an explanatory diagram showing an operation example in which the waste plastic blowing amount is adjusted so as not to change the coke bed upper end level in the embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a change in ηCO when polyethylene is blown into a coke bed in an example of the present invention.
FIG. 7 is an explanatory diagram showing a coke lowering speed when polyethylene is blown in an example of the present invention.
[Explanation of symbols]
1 Dust reduction furnace
2 Charger
3 buckets
4 bells
5 Movable armor
6 Charging guide
7 Furnace
8 Exhaust gas pipe
9 tuyere
9a Primary tuyere (lower tuyere)
9b Secondary tuyere (upper tuyere)
11 Furnace center
12 Furnace area
13 Coke bed

Claims (8)

When charging iron dust, dust agglomerates, and coke into a dust reduction furnace with multi-stage air tuyeres,
While blowing air that does not form a raceway from the primary tuyere to the coke bed and blowing granular waste plastic, it is controlled so that the upper level of the coke bed does not change,
A method for operating a dust reduction treatment furnace, characterized in that air is blown without forming a raceway from a secondary tuyere to a packed bed above a coke bed, and granular waste plastic is blown in for treatment. 2. The method for operating a dust reduction treatment furnace according to claim 1, wherein granular waste plastic is blown from the primary tuyere under an oxygen-enriched blast at room temperature. The method for operating a dust reduction treatment furnace according to claim 2, wherein the oxygen enrichment amount of the normal temperature blast is 2% or more. The method for operating a dust reduction treatment furnace according to any one of claims 1 to 3, wherein the waste plastic is blown into the secondary tuyere while blowing hot air at 700 ° C or less. The method for operating a dust reduction treatment furnace according to any one of claims 1 to 4, wherein the amount of waste plastic blown from the primary tuyere is adjusted so that the descending speed of the raw fuel is constant. The method for operating a dust reduction treatment furnace according to any one of claims 1 to 5, wherein a waste plastic blowing position from the secondary tuyere is set in a region above the coke bed. The method for operating a dust reduction treatment furnace according to any one of claims 1 to 6, wherein an amount of waste plastic blown is set to 0.2 kg / Nm ³ or less. The iron scrap is mixed with a large diameter coke and charged in the center of the furnace, and the dust agglomerate is mixed with the small diameter coke and charged in the periphery of the furnace. A method for operating the dust reduction furnace described in the above.

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