JP4246346B2 - Waste plastic treatment method for dust reduction furnace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waste plastic for a dust reduction treatment furnace in which waste plastic is blown from a blower tuyere when melting and reducing iron scrap and dust agglomerate in a dust reduction treatment furnace having a multistage blower tuyere. It relates to the processing method.
[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, but usually the blast furnace and cupola tuyere are configured as a single stage, and the dust reduction treatment furnace The specific operating conditions of the waste plastic blowing process in a melting furnace having two or more multi-stage tuyere as described above have not been elucidated.
[0007]
In view of the above problems, the object of the present invention is to set specific operating conditions for waste plastic blowing treatment in a dust reduction treatment furnace having a multistage blower tuyere, while maintaining stable operation of the dust reduction treatment furnace, It is an object of the present invention to provide a waste plastic treatment method for a dust reduction treatment furnace that can efficiently incinerate waste plastic.
[0008]
[Means for Solving the Problems]
  In order to achieve the above object, the waste plastic treatment method for a dust reduction treatment furnace according to the present invention is a method of melting and charging iron dust, dust agglomerate, and coke into a dust reduction treatment furnace having a multistage blower tuyere. When performing the reduction process, set the upper level of the coke bed between the upper tuyeres and the lower tuyere, and perform the main ventilation with the lower tuyere as the main tuyere,The upper tuyere is set so that the tuyere diameter and the protruding position in the furnace do not form a raceway,From the upper tuyereUnder hot air blowing below 700 ° CTop of coke bedOver 800 ℃Packed bedregionWhile blowing without forming a raceway, the waste plastic is blown and processed.
[0010]
Moreover, when performing oxygen-enriched air blowing at room temperature from the main tuyere, the oxygen enrichment rate is preferably less than 30%.
[0011]
  In addition, waste plastic blowing positionThe lordIt is preferable to set 30 cm to 40 cm above the tuyere.
[0012]
And the amount of waste plastic blown is 0.2kg / Nm.^ThreeIt is preferable to set the following.
[0013]
In addition, it is preferable that iron scrap is mixed with large-diameter coke and charged in the furnace center, and dust agglomerate is mixed with small-diameter coke and charged in the furnace periphery.
[0014]
According to the present invention, in a dust reduction treatment furnace having a multi-stage ventilation tuyere, the upper level of the coke bed is set between the upper tuyeres and the lower tuyere, and the main vent is used with the lower tuyere as the main tuyere. The process is performed by blowing granular waste plastic from the upper tuyere into the packed bed above the coke bed 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.
[0015]
Waste plastic is efficiently incinerated by blowing waste plastic from the upper 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, hot air blowing at 700 ° C. or lower is performed.
[0016]
The reason why the temperature of the hot air blowing from the upper tuyere is set to 700 ° C. or less is that when the blowing temperature exceeds 700 ° C., the combustion reaction of the coke and the solution loss reaction are promoted, and the coke ratio is not necessarily reduced. .
[0017]
In addition, when oxygen-enriched ventilation at room temperature is performed from the main tuyere, the oxygen enrichment rate is set to less than 30%. If the oxygen enrichment rate is 30% or more, the ventilation from the main tuyere is close to pure oxygen blowing. This is because the gas combustion temperature is 3000 ° C. or higher, which promotes the wear of refractories near the furnace bottom and hinders long-term continuous operation.
[0018]
Furthermore, the waste plastic blowing position is set to an area of 800 ° C. or more above the coke bed, specifically, 30 cm to 40 cm above the main tuyere, so that the oxygen during blowing from the main tuyere is 30 to 40 cm above the main tuyere. In position, it burns completely by reaction with coke and is hot and high in CO₂Therefore, if waste plastic is blown in along with air from this part, C in the waste plastic is preferentially burned and CO₂This is because the coke consumption can be suppressed.
[0019]
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.
[0020]
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.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, although the embodiment in the waste plastic processing method of the dust reduction processing furnace of the present invention will be described in detail with reference to the accompanying drawings, the present invention is not limited to the following embodiment.
[0022]
Fig.1 (a) is the schematic which shows the dust reduction processing furnace used for the waste plastic blowing 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.
[0023]
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 is formed as a two-stage tuyere of a lower tuyere 9a and an upper tuyere 9b in FIG. Further, a plurality of these tuyere 9a, 9b are arranged at appropriate intervals in the circumferential direction of the furnace body 7.
[0024]
The blowing conditions are such that the lower tuyere 9a is the main tuyere, hot air blowing is performed from the main tuyere 9a or oxygen-enriched blowing at room temperature, and hot air blowing is performed from the upper tuyere 9b. When performing oxygen-enriched ventilation at normal temperature from the main tuyere 9a, the air is blown with the oxygen enrichment amount set to less than 5%. On the other hand, when hot air is blown from the upper 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.
[0025]
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 including a lower tuyere 9a and an upper tuyere 9b. May be provided. For example, in the case of three stages, the tuyere located on the side of the coke bed is used as the main tuyere, and main air blows from this main tuyere to maintain combustion efficiency, and from the tuyere directly above the coke bed. Waste plastic blowing is performed.
[0026]
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).
[0027]
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 upper tuyere 9b and the lower tuyere (main tuyere) 9a. The Waste plastic is blown from the upper tuyere 9b into the packed bed above the coke bed under hot air.
[0028]
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.
[0029]
Next, the waste plastic processing method of the present invention that is carried out using the dust reduction processing 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 the waste plastic is blown into the upper stage tuyere 9b for processing.
[0030]
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.
[0031]
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.
[0032]
The operation of the dust reduction furnace consists of the coke bed top level height, the division charging method according to the size of the raw fuel, and the main tuyere blowing conditions (blowing temperature, oxygen enrichment, tuyere diameter, protruding position, blowing Ratio), and the amount of waste plastic blown in. In the present invention, as described above, the height of the upper end level of the coke bed 13 is set between the upper tuyere 9b and the lower tuyere (main tuyere) 9a. This is because waste plastic is blown into the packed bed above the coke bed from the upper tuyere 9b, specifically, the region of 800 ° C. or more, so that the C in the waste plastic is preferentially burned and₂This is because the coke consumption can be suppressed. The region above 800 ° C. above the coke bed is a temperature region where a solution loss reaction described later occurs, and corresponds to 30 to 40 cm above the main tuyere.
[0033]
Therefore, when the upper end level of the coke bed 13 is set between the upper tuyere 9b and the main tuyere 9a and the waste plastic is blown from the upper tuyere 9b into the region above 800 ° C above the coke bed, the incineration process is performed. Efficiency is good.
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.
[0034]
That is, in the waste plastic processing method of the present invention, the upper level of the coke bed 13 is set between the upper tuyere 9b and the lower tuyere 9a in the dust reduction furnace 1 having a multistage blower tuyere. Main air is blown with the mouth 9a as the main tuyere, and granular waste plastic is blown from the upper tuyere 9b to the packed bed (region of 800 ° C or higher) above the coke bed without forming a raceway under hot air. It is out. 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.
[0035]
By blowing waste plastic directly from the upper tuyere 9b into the packed bed at the top of the coke bed, the waste plastic is incinerated efficiently, but because of the large amount of combustion product gas, the gas temperature decreases, and iron scrap dissolution / dust reduction In the process of dissolving the metal like this, it becomes a shortage of heat. In order to make up for this lack of heat, in the present invention, hot air is blown at 700 ° C. or lower.
[0036]
When the hot air is blown from the upper tuyere 9b, the blowing temperature is set to 700 ° C. or less. When the blowing temperature exceeds 700 ° C., the combustion reaction and the solution loss reaction of coke are promoted in addition to the waste plastic, and the coke ratio This is because it is not necessarily reduced. In this way, when the waste plastic is blown under hot air blowing at 700 ° C. or lower, waste plastic having low combustion heat or waste plastic having a large particle size of about several mm can be used.
[0037]
On the other hand, when performing oxygen-enriched ventilation at room temperature from the main tuyere 9a, the oxygen enrichment amount is less than 30%. If 30% or more, blowing from the main tuyere is close to pure oxygen blowing, This is because the theoretical gas combustion temperature is 3000 ° C. or more, which accelerates the wear of refractories near the furnace bottom and hinders long-term continuous operation.
[0038]
As described above, when waste plastic is blown under hot air blowing, waste plastic having a large particle size of about 5 to 10 mm can be used, but waste plastic blowing under normal temperature oxygen-enriched blowing. When performing, for example, a small waste plastic having a particle size of 5 mm or less is used.
[0039]
Furthermore, 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 it cannot be used as a fuel substitute for coke and cannot be used effectively.
[0040]
Next, it will be explained that adjustment of the coke bed height in the lower part of the dust reduction treatment furnace and that changes in the air flow rate, tuyere diameter, tuyere protruding position, etc. are effective for ηCO control.
FIG. 4 shows the results of an experiment by an offline simulator in which the coke particle size and the amount of air blown (gas flow rate) were changed to investigate the transition of the coke bed height from the tuyere and the ηCO at that portion. According to FIG. 4, oxygen and enriched oxygen in the air blown from the tuyere combusts with coke in the reaction of the following formula (2) to produce CO.₂ To generate O₂ Complete combustion at the site where the disappearance occurs. This part has the highest gas temperature, and above this, the endothermic reaction (1) below proceeds, so that ηCO is lowered and the gas temperature is also lowered.
C + CO₂ = 2CO (1)
C + O₂ → CO₂     ... (2)
[0041]
When the coke particle size is reduced, the combustion rate of equation (2) is increased, so that the maximum gas temperature (O₂ = 0% and ηCO = 100%) is close to the tuyere. In addition, when the air flow rate is increased and the gas flow rate is increased, the in-furnace flow rate of oxygen blown from the tuyere increases and the contact time with C near the tuyere is shortened. The reaction extends to the top of the furnace. Therefore, when the flow rate is increased with the same coke particle size, the overall ηCO in the furnace becomes higher than when the flow rate is low. Protruding the main tuyere into the furnace or reducing the tuyere diameter and raising 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 protruding position are effective means for controlling ηCO in the furnace.
[0042]
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.
[0043]
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 in the furnace center, and raw materials with a low metallization rate, such as dust agglomerates, are loaded in the furnace periphery. 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.
[0044]
When directing this operation, the upper tuyere has a structure in which the tuyere tip protrudes into the furnace rather than the furnace wall, and basically the tip position of the upper tuyere is 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.
[0045]
The reason why the upper tuyere is set at the boundary between the central part and the peripheral part of the furnace is that the air blown from the upper 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.
[0046]
In this operation, the appropriate air volume of the upper 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 upper tuyere, and ideal operation is possible with respect to the furnace center.
[0047]
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.
[0048]
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.
[0049]
Next, a control method for 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. If the coke ratio is not appropriate, the unreduced FeO content is melted and reduced at the lower part of the furnace, and the coke bed is consumed. 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.
[0050]
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.
[0051]
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. .
[0052]
Simple methods for controlling or monitoring the coke bed height include visual observation at the lower tuyere and determination based on the pressure loss value in the furnace. The observation at the lower tuyere can determine that at least the melting part 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.
[0053]
Further, as a method for 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.
[0054]
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 (3) 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))} (3)
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 )
[0055]
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.
[0056]
FIG. 5 shows CO in the coke bed when waste plastic is blown into a 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     ... (4)
C + CO₂  → 2CO (5)
[0057]
In FIG.₂ As shown in the concentration curve, as it goes from the blower tuyere to the upper side of the coke bed, the reaction of the equation (4) results in CO 2.₂  Concentration increases, O₂Is consumed and decreased. And O₂  Above the position where the disappearance of CO2 occurs, the reaction of the formula (5) causes CO 2₂  The concentration decreases and the CO concentration begins to increase.
[0058]
In the reaction of the formula (4), C in the coke is effectively used by an exothermic reaction, but in the reaction of the formula (5), C is not effectively used by an endothermic reaction. Therefore, it is necessary to make the coke react as much as (4) as much as possible.₂ High temperature CO₂ When contacted, coke solution loss occurs due to the reaction of equation (5), and coke is wasted.
[0059]
【Example】
Hereinafter, examples of the waste plastic blowing method of the dust reduction treatment furnace of the present invention will be described, but the present invention is not limited to the following examples.
Filling the upper part of the coke bed under a blowing condition where hot air is blown without forming a raceway from the tuyere located above the main tuyere, aiming to reduce the coke ratio and waste plastic treatment of the dust reduction furnace Waste plastic injection experiment (hot model experiment) was performed on the layer.
In addition, the combustibility of waste plastic was investigated from dust properties collected at each part of the packed bed above the coke bed, and the combustion behavior and reaction behavior of waste plastic were investigated from the coke consumption rate (descent behavior).
[0060]
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 was blown with hot air, and the temperature was 500 ° C. The amount of waste plastic blown is 0.12 kg / Nm.^ThreeIt was.
[0061]
As a result, first of all, when polyethylene is blown, 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. Moreover, when the upper tuyere position was set to 20 cm, 30 cm, 40 cm, and 50 cm from the main tuyere, and the combustion / pyrolysis behavior of the polyethylene particles and the coke consumption rate were investigated, 30-40 cm from the main tuyere. When the upper tuyere was installed at the site, the coke consumption rate was the slowest and the preferential consumption of polyethylene was confirmed.
[0062]
Second, CH_FourAccording to the analytical quantitative results, as shown in FIG.₂H_FourDisappearance and CH_FourIn this region, it is determined that the combustion and thermal decomposition of polyethylene are almost completed.
[0063]
Third, when polyethylene is blown from the upper tuyere under conditions where no air is blown from the main tuyere, as shown in FIG. 7, the descent of coke is stagnant at the upper part of 10 to 20 cm above the upper tuyere (changes at least 30 minutes or more) Was not confirmed). That is, in the upper tuyere position from 10 cm to 20 cm upper part, it was confirmed that the combustion reaction of coke was very small and polyethylene was burning and reacting.
[0064]
From the above experimental results, when hot air is blown, blowing of waste plastic from the tuyere above the main tuyere is effective for the treatment of waste plastic, and when waste plastic is blown into 30 to 40 cm above the main tuyere. It was confirmed that stable operation was possible.
[0065]
【The invention's effect】
As described above, according to the present invention, a specific operation condition of waste plastic blowing treatment in a dust reduction treatment furnace having a multistage blower tuyere is set, and the dust reduction treatment furnace is blown by blowing from the main tuyere. The waste plastic can be efficiently incinerated by blowing waste plastic from the upper tuyere while maintaining stable operation.
[Brief description of the drawings]
FIG. 1 is a dust reduction treatment furnace used in the waste plastic treatment method of a dust reduction treatment furnace of the present invention, wherein (a) is a schematic diagram showing the overall configuration, and (b) is a furnace center portion of the charging device. The schematic which shows the charging condition to a furnace, (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 is an explanatory diagram showing an experimental result by an offline simulator of changes in coke bed height and ηCO.
Fig. 5 CO in the furnace₂It is explanatory drawing which shows a density | concentration curve.
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 descending 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 Lower tuyere
9b Upper tuyere
11 Furnace center
12 Furnace area
13 Coke bed

Claims (5)

When charging iron dust, dust agglomerates, and coke into a dust reduction furnace with multi-stage air tuyeres,
The upper level of the coke bed is set between the upper tuyere and the lower tuyere, and the main tuyere is used as the main tuyere, and the upper tuyere forms the raceway with the tuyere diameter and the protruding position in the furnace. The air is blown without forming a laceway from the upper tuyere to the packed bed area above 800 ° C under hot air blowing at 700 ° C or below from the upper tuyere, and treated by blowing granular waste plastic. A waste plastic treatment method for a dust reduction treatment furnace. If the main tuyere perform oxygen enrichment blowing cold, waste plastic processing method of dust reduction treatment furnace according to claim 1, characterized in that the oxygen-enriched rate is less than 30%. The waste plastic treatment method for a dust reduction treatment furnace according to claim 1 or 2 , wherein a packed bed region of 800 ° C or more above the coke bed is 30 to 40 cm above the main tuyere. The waste plastic treatment method for a dust reduction treatment furnace according to any one of claims 1 to 3 , wherein the amount of waste plastic blown is set to 0.2 kg / Nm ³ or less. Was charged with scrap into the furnace center portion is mixed with large diameter coke, any of claims 1-4, characterized by charging the dust lump Naruko into the furnace peripheral portion is mixed with a small diameter of the coke A waste plastic treatment method for a dust reduction treatment furnace according to claim 1.

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