JP4394766B2 - Complex waste disposal method - Google Patents

Description

但し、ｒｉ：中心部と周辺部との無次元境界半径（−）
Ｗｍ(c) ： 中心部に装入する廃棄物重量（ｋｇ／チャージ）
Ｗｃ(c) ： 中心部に装入する燃料重量（ｋｇ／チャージ）
Ｗｍ(p) ： 周辺部に装入する廃棄物重量（ｋｇ／チャージ）
Ｗｃ(p) ： 周辺部に装入する燃料重量（ｋｇ／チャージ）
ρｍ(c) ： 中心部に装入する廃棄物の嵩密度（ｋｇ／ｍ³）
ρｃ(c) ： 中心部に装入する燃料の嵩密度（ｋｇ／ｍ³ ）
ρｍ(p) ： 周辺部の装入する廃棄物の嵩密度（ｋｇ／ｍ³ ）
ρｃ(p) ： 周辺部に装入する燃料の嵩密度（ｋｇ／ｍ³ ）
【００６４】
なお、このｒｉは、無次元半径で表されており、炉中心部と炉周辺部の装入物の降下速度を一定とした場合の境界位置を示している。このｒｉで示される境界位置を調節するための装入方法については、種々考えられるが、ベル式の装入装置を使用する場合でも、アーマーを使用し、装入チャージ毎に中心装入、周辺装入を交互に繰り返して装入することにより、一部混合層が生成するものの、所定の境界設定は可能である。
【００６５】
また、低コークス比操業を行うとともに、羽口送風量を上段羽口送風量＞下段羽口送風量に設定する。これは、廃棄物チャーの燃焼を極力上段羽口の送風で行わせることを目的としているためである。
【００６６】
さらに、下段羽口から常温の酸素富化空気とともに、廃プラスチックの吹き込みを行う。廃プラスチックの吹き込みを併用するのは、廃プラスチックを燃料として併用し、その燃焼ガスを熱源として使用することにより、低コークス化を実現するためである。
【００６７】
また、コークス使用量の低減について考察した結果、次のことから廃プラスチックの吹き込み位置が廃プラスチックの果たす役割に大きく影響することが判明した。
図７は、通常のコークスベッド内に廃プラスチックを吹き込んだ場合のコークスベッド内でのηＣＯの変化の一例を示す図である。
コークス中のＣまたは廃プラスチック中のＣの消費には下記の２形態が存在する。
Ｃ ＋ Ｏ₂ → ＣＯ₂ ・・・（４）
Ｃ ＋ ＣＯ₂ → ２ＣＯ ・・・（５）
【００６８】
（４）式の反応は、発熱反応でコークス中のＣが有効に利用されるが、（５）式の反応は吸熱反応でＣが有効に利用されないことになる。従って、コークスには極力（４）式の反応をさせる必要があるが、Ｏ₂ のない状態で、高温のＣＯ₂に接すると（５）式の反応によりコークスのソルーションロスが起こり、コークスが無駄に消費されることになる。
【００６９】
廃プラスチックはコークスに比べ燃焼速度が速いため、コークスベッド内に廃プラスチックを吹き込むと、吹き込まない場合に比べて、Ｏ₂ の消失位置が下ることになる。従って、廃プラスチックを吹き込まない条件のままで、むやみにコークスベッド内へ廃プラスチックを吹き込んでも、Ｏ₂ の消失位置より上方にコークスが存在することになり、（４）式のコークス消費量を減少できても、（５）式でコークス消費量が増大し、結果的に廃プラスチック吹き込みがコークス消費量の低減に寄与することができなくなる。
【００７０】
こうした状況を回避し、廃プラスチック吹き込みによりコークス代替を行わせるには、以下の二つの方法が有効である。即ち（５）式の反応をコークスベッド内で行わせないようにするか、（５）式で反応するコークス中のＣを廃プラスチック中のＣに置き換えることによりコークスのソルーションロスを起こさせないようにすることである。
【００７１】
第一の方法は、下段羽口から吹き込まれたＯ₂ が廃プラスチックも加味して消失する高さにコークスベッドの上端レベルを設定し、Ｏ₂ の存在しない領域にはコークスも存在しないようにして、廃プラスチックを下段羽口レベルとコークスベッド上端レベルとの間に吹き込む方法である。この場合、廃プラスチックの吹き込み位置は、下段羽口レベルとコークスベッド上端レベルとの間であれば下段羽口をも含めて任意の位置で良く、一段でも復数段でも良い。
【００７２】
第二の方法は、下段羽口から吹き込まれたＯ₂ が廃プラスチックも加味して消失する高さよりコークスベッドの上端レベルを上方に設定する場合で、このときは、廃プラスチックを下段羽口レベルとコークスベッド上端レベルとの間に吹き込むとともに、Ｏ₂ の存在しないコークスベッド上部領域にもコークスに代替してソルーションロスを起こさせるための廃プラスチックを吹き込む方法である。この場合、下部の廃プラスチック吹き込み位置は、下段羽口レベルとＯ₂ 消失点レベルとの間であれば下段羽口をも含めて任意の位置で良く、一段でも複数段でも良い。また、上部の廃プラスチック吹き込み位置もＯ₂ 消失点レベルとコークスベッド上端レベルとの間であれば任意の位置で良く、一段でも複数段でも良い。この方法によれば、上部に吹き込む分だけ廃プラスチックの吹き込み量を増やすことが可能となる。
【００７３】
【実施例】
図８は、本実施例の複合廃棄物の処理方法を実施する装置構成を示す概略図である。図示するように、多機能溶融炉１内には、不図示の装入装置によって廃家電等の複合廃棄物が装入される。本実施例では、複合廃棄物は、解体されて一部処理されるか、或いは解体されずにまるごと処理される。多機能溶融炉１の操業条件は、下記表１に示されている。多機能溶融炉１から出銑される溶銑中のＣｕ分は除去され、排気ガスはサイクロン１４を介して排ガス処理装置１５によって燃焼，冷却処理され、煙突１６から放出される。
【００７４】
【表１】

表１に示すように、実施例１〜４はηＣＯを２０％に制御する場合を、実施例５〜１０はηＣＯを４５％に制御する場合を示している。廃家電は１０００ｋｇずつ装入され、ＣＲは各実施例のコークス比を表わしている。下段羽口からコークスベッド内へ酸素富化量２％以上の常温の酸素富化空気が吹き込まれ、上段羽口から蒸気が吹き込まれる。羽口送風量は、上段羽口送風量（２次羽口送風量）＞下段羽口送風量（１次羽口送風量）となるように設定されている。上段羽口からの蒸気吹き込み量は、実施例１〜５が３ｇ／Ｎｍ³ であり、実施例６が３２０ｇ／Ｎｍ³ 、実施例７，８が４６０ｇ／Ｎｍ³ 、実施例９が５５０ｇ／Ｎｍ³ 、実施例１０が６５０ｇ／Ｎｍ³ である。
【００７５】
複合廃棄物の処理ではタールなどの排出があるため、炉頂ガスの温度を極力３００℃以上に制御して操業することが好ましく、より好ましくは３００℃〜４５０℃の範囲にあることが好ましい。したがって、特に実施例１、６および７の条件が好適である。
【００７６】
実施例１〜１０では、下段羽口と上段羽口との間にコークスベッド上端レベルを設定し、下段羽口からコークスベッド内へ酸素富化量８％以上の常温の酸素富化空気を吹き込み、上段羽口から蒸気を吹き込むことにより、廃家電等の複合廃棄物に含まれるプラスチックを燃料成分として使用することができ、コークス使用量を低減しても多機能溶融炉の安定操業を行うことができた。
【００７７】
【発明の効果】
以上説明したように、本発明によれば、多機能溶融炉の具体的な処理条件を設定することにより、廃家電等の複合廃棄物を解体，分別せずに安全かつ効率的に溶融処理することができ、廃プラスチック処理が行えるとともに、コークス使用量を低減して溶融炉の安定操業を行うことができるという優れた効果を発揮する。
【図面の簡単な説明】
【図１】本発明の複合廃棄物の処分方法に使用する多機能溶融炉であり、（ａ）はその全体構成を示す概略図、（ｂ）はその装入装置の炉中心部への装入状況を示す概略図、（ｃ）はその装入装置の炉周辺部への装入状況を示す概略図である。
【図２】コークスベッドの上端レベルを示す概略図である。
【図３】炉半径方向区分け装入状況を示す概略図である。
【図４】ストックレベル変更試験における排ガスηＣＯとの関係を示す説明図である。
【図５】コークスベッド高さとηＣＯの推移のオフラインシミュレータによる実験結果を示す説明図である。
【図６】同じコークス粒度で流速を変化させた場合のηＣＯの変化を示す説明図である。
【図７】廃プラスチック吹き込み時のηＣＯの変化を示す説明図である。
【図８】本実施例の複合廃棄物の処理方法を実施する装置構成を示す概略図である。
【符号の説明】
１ 多機能溶融炉
２ 装入装置
３ バケット
４ ベル
５ 可動アーマー
６ 装入ガイド
７ 炉体
８ 排ガス管
９ 羽口
９ａ 下段羽口
９ｂ 上段羽口
１１ 炉中心部
１２ 炉周辺部
１４ サイクロン
１５ 排ガス処理装置
１６ 煙突[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of melting and treating composite waste such as waste home appliances containing metals and plastics in a multi-functional melting furnace, and in particular, the total iron content is 10% <TotalFe (hereinafter referred to as “T.Fe”). It relates to a method for treating composite waste capable of melting <80% of composite waste.
[0002]
[Prior art]
Waste home appliances such as used washing machines, refrigerators, and air conditioners are composite wastes that contain 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.
[0003]
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 or the like and melted, and the sorted plastic is crushed and landfilled.
[0004]
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, the dismantling and separation work of the composite waste requires a lot of labor, and the increase in the number of man-hours has led to an increase in cost, which has been an impediment to the formation of a recycling society. In particular, today, when household appliances are diversified, the tendency is remarkable.
[0005]
Therefore, in recent years, attention has been focused on the development of a method for recovering useful metal materials by directly charging the composite waste into a vertical melting furnace without melting it and melting it. As a technology related to this, for example, Japanese Patent Laid-Open No. 5-222424 proposes an invention relating to “a disposal method for protecting the environment of organic and inorganic non-metallic substances in used vehicles or used equipment”. Yes.
[0006]
The present invention states that "the incidental substance is chemically reacted with the iron oxide contained in the steel scrap or iron ore by putting the incidental substance together with the steel scrap of the used vehicle or the used equipment into the vertical furnace. Is used as a flux to chemically reduce and form slag, at least partially supplementing conventional fluxes for this purpose, such as coke, oil or gas. " Disposal to protect the environment of organic and inorganic non-metallic associated substances in used vehicles or other mass-produced products such as washing machines and refrigerators.
[0007]
[Problems to be solved by the invention]
By the way, composite waste contains a large amount of plastics, but even when plastics are contained, it can be safely disposed of in a waste melting furnace without generating harmful substances. . However, since the temperature of the waste gradually rises as it descends in the furnace, the plastics are pyrolyzed and gasified before reaching the bottom of the furnace, resulting in a high calorific value of the plastics and as a reducing material. Is not effectively utilized during high temperature melting.
[0008]
Further, the invention relating to the disposal method disclosed in Japanese Patent Laid-Open No. 5-222424 is a disposal method for crushed metal scraps, partially used vehicles or used devices that have been partially dismantled, No idea has been made to melt the composite waste without disassembling it.
[0009]
Furthermore, in this disposal method, (1) control means for preheating zone, combustion zone and melting zone in vertical furnace, (2) balance of product gas, slag, hot metal, and (3) combustion exhaust gas are completely Whether combustion or partial combustion, (4) combustion space is necessary, (5) charging method (necessity of gas flow control), (6) peripheral flow formation, central flow formation, or (7) multi-stage injection No particular consideration is given to specific processing conditions such as the upper tuyere and the lower tuyere for the main tuyere.
[0010]
In view of the above problems, the object of the present invention is to effectively utilize the high calorific value of plastics during melting at high temperature and the ability as a reducing material, and set specific treatment conditions to An object of the present invention is to provide a method for treating composite waste that can be melted safely and efficiently without dismantling and separation.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention, after charging coke into a melting furnace having a two-stage fan tuyere to form a coke bed, contains metal and plastic, and has a total iron content [Total When the composite waste in which Fe is 10 mass% <[Total Fe] <80 mass% is charged with coke and dried, pyrolyzed, burned and melted to melt the composite waste, the composite waste diameter without dismantling, the larger the metal content is mixed with a large diameter coke was charged out of the composite waste fracture after grinding, the composite disposal after grinding broken into the furnace peripheral portion One with a small metal content is mixed and charged with small-diameter coke, the upper level of the coke bed is set between the upper tuyeres and the lower tuyeres, and the tuyere air volume is sent to the upper tuyeres. Set air volume> lower tuyere air volume, lower wing With oxygen-enriched air enriched amount of 2% or more at normal temperature without forming coke bed f raceways from those blowing waste plastics.
[0012]
Furthermore, it is preferable to cool the upper part of the furnace by blowing steam from the upper tuyere.
[0019]
According to the present invention, when composite waste such as waste home appliances is melted, the upper level of the coke bed is set between the upper tuyeres and the lower tuyere, and oxygen at room temperature is supplied from the lower tuyeres to the coke bed. Blowing enriched air. This is due to 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 “waste char”) contains a large amount of iron in addition to C. Therefore, if C in this waste char is burned with oxygen-enriched air, the operational effect is large, and for this purpose, it is necessary to set the upper level of the coke bed between the upper and lower tuyere. It is.
[0020]
The conventional treatment method has a total iron content of about 50% <T. Although the composite waste of Fe was targeted, the treatment method of the present invention has 10% <T. Suitable for the treatment of complex waste with a wide range of Fe <80%. In the present invention, the lower limit of the total iron content of the composite waste is 10% <T. The reason why Fe is selected is that 10% or less is treated as normal combustible waste, and the upper limit is set to T.I. The reason why Fe <80% is that 80% or more is pretreated such as crushing / separation processing of composite waste, and is generally treated as iron scrap.
[0021]
Also, the oxygen enrichment amount of oxygen enriched air at room temperature is set to 2% or more. If it is less than 2%, it is difficult to maintain the coke bed temperature under normal temperature ventilation, and slag and metal after combustion and melting of waste char This is because it hinders the temperature rise.
[0022]
Further, steam is blown from the upper tuyere to prevent heat surplus by cooling the upper part in the furnace.
[0023]
In addition, while operating at low coke ratio, setting the tuyere air flow rate to the upper tuyere air flow rate> lower tuyere air flow rate increases the air flow rate of the upper tuyere and increases the combustion rate of waste char This is to contribute to the reduction of the coke ratio.
[0024]
Furthermore, the reason why the waste plastic is blown together with the oxygen-enriched air at room temperature from the lower tuyere is to realize low coke by using the combustion gas of the waste plastic as a heat source.
[0025]
The reason for controlling the temperature increase rate of the raw fuel in the furnace by changing the stock level of the charge is to properly control the exhaust gas ηCO.
[0026]
Furthermore, large-diameter composite waste that is not dismantled in the furnace center, crushed composite waste that has a high metal content, and large-diameter coke In order to ensure stable operation of a multi-function melting furnace, a small amount of coke with a small metal content and small diameter coke are charged by melting at the center of the furnace and forming a gas flow at the center of the furnace. To do.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the composite waste disposal method of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments.
Fig.1 (a) is the schematic which shows the multifunctional melting furnace used for the disposal method of the composite waste of this invention. As shown in the figure, a charging device 2 is provided at the top of the multi-function 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 the raw material and fuel in a radial direction.
[0028]
An exhaust gas pipe 8 for exhausting counterflow gas in the furnace is provided on the upper portion of the furnace body 7 of the multi-function melting furnace 1. The exhaust gas system connected to the exhaust gas pipe 8 is used for a refuse melting furnace.
[0029]
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 this embodiment. Further, a plurality of these tuyere 9a, 9b are arranged at appropriate intervals in the circumferential direction of the furnace body 7.
[0030]
The blowing conditions are such that oxygen enriched air having an oxygen enrichment amount of 2% or more is blown from the lower tuyere 9a and steam is blown from the upper tuyere 9b. In addition, the tuyere 9a and 9b are configured to be able to change the tuyere diameter and the protruding position in the furnace so that a raceway can be formed when a powdered iron source or waste plastic is blown.
[0031]
In the present embodiment, the multi-stage tuyere 9 provided in the side wall height direction of the furnace body 7 is formed as a two-stage tuyere of a lower tuyere 9a and an upper tuyere 9b, but at least the lowest stage If oxygen-enriched air is blown from the tuyere, three or more tuyere may be provided. For example, when waste plastic is processed in the case of three stages, it is also one way to form a raceway at the tuyere located in the middle stage. In this case, the middle tuyere has a raceway to form a small diameter coke. The tuyere that blows waste plastic into it is the third tuyere that maintains the combustion efficiency in the furnace.
[0032]
In addition, the raw material and fuel can be charged separately into the furnace central part 11 and the furnace peripheral part 12, and as described above, charging that can be divided and charged in the radial direction at the top of the furnace is possible. The apparatus 2 is included (FIGS. 1B and 1C). When the composite waste such as waste home appliances is charged as it is into the furnace center 11 without disassembling, the charging device 2 is retracted, and a charging device for large-diameter items (not shown) is arranged. is there.
[0033]
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, oxygen-enriched air is blown into the coke bed 13 from the lower tuyere 9a.
[0034]
The multifunctional melting furnace 1 is a melting furnace that performs an intermediate process between a cupola and a garbage melting furnace. In other words, composite waste such as waste home appliances is dry-distilled in the temperature rising process after charging at the furnace top, and oil such as tar and dry distillation gas are scattered from the top of the furnace. Absent. Also, because of the high iron content, it is not a combustible waste treatment like a waste melting furnace. Normally, combustible waste is T.W. Fe <10% and not much iron.
[0035]
The waste melting furnace and cupola are common in that oxygen-containing gas is blown into a vertical furnace having a coke packed bed, but there are the following differences. That is, the waste melting furnace dry-distills and preheats municipal waste containing a large amount of combustible materials and melts the residue. Moreover, it is mainly combusted and generates a large amount of gas. Furthermore, dust collection, harmful gas treatment, exhaust gas purification equipment and methods, dezincing, detinning processes, low P, S, and Cu mixing solutions are necessary, and unloading adjustment and blowout prevention are issues. is there. Incombustibles melt and are discharged as slag.
[0036]
The multi-functional melting furnace 1 melts iron scrap, dust and the like to produce hot metal. Mainly melting iron, waste plastic is used as fuel. The generated gas is mainly used as fuel gas (partial combustion).
[0037]
Next, the processing method of the composite waste of this invention implemented using said multifunctional melting furnace 1 is demonstrated.
The raw materials charged from the top of the furnace are composite waste such as waste home appliances (as-is without dismantling) and composted waste after crushing. The fuel is mainly coke, and waste plastic is used as needed. .
[0038]
In the treatment method of the present invention, the total iron content is 10% <T. Suitable for the treatment of composite waste with Fe <80%. In the present invention, the lower limit of the total iron content of the composite waste is 10% <T. The reason why Fe is selected is that 10% or less is treated as normal combustible waste, and the upper limit is set to T.I. The reason why Fe <80% is that 80% or more is pretreated such as crushing / separation processing of composite waste, and is generally treated as iron scrap.
Generally, waste home appliances contain about 37% iron (T.Fe), about 37% waste plastics, and waste cars contain about 70-80% iron (T, Fe).
[0039]
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. As shown in FIG. 3, the sorting and charging method is performed by mixing a large-diameter composite waste as it is and a composite waste after crushing with a large metal content with a large-diameter coke. It is aimed at operation with high reaction efficiency by mixing the mixed waste after crushing with small diameter coke and charging it into the peripheral part. That is, by implementing the charging of the raw material and the fuel, the gas flow at the center of the furnace can be promoted and the high ηCO condition can be continued.
[0040]
The operation of the multi-function melting furnace is controlled by adjusting the coke bed top level height, stock level position, sorting charging method according to the size of the raw fuel, lower tuyere ejection position, etc. In the present invention, as described above, the height of the upper end level of the coke bed 13 is set between the lower tuyere 9a and the upper tuyere 9b. This is due to the following reason. That is, the waste char in a state after the composite waste is charged and carbonized in the preheating process contains a large amount of iron in addition to C. Therefore, when C in the waste char is burned with oxygen-enriched air, the coke ratio is greatly reduced. 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 do.
In the coke bed, the combustion reaction of coke 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.
[0041]
In particular, in the treatment method of the present invention, oxygen-enriched air having an oxygen enrichment of 2% or more is blown from the lower tuyere 9a and steam is blown from the upper tuyere 9b. The oxygen enrichment amount of the oxygen-enriched air at room temperature is set to 2% or more. If the oxygen enrichment amount is less than 2%, it is difficult to maintain the coke bed temperature under normal temperature ventilation, and the slag and metal rise after combustion and melting of waste char. This is because it interferes with temperature. The reason why steam is blown from the upper tuyere is to prevent heat surplus by cooling the upper part in the furnace. Furthermore, since the lower tuyere 9a is directed to operation at a low fuel ratio, main air is blown without forming a raceway, and the combustion rate is increased to a high ηCO condition. On the other hand, when the waste plastic is blown from the lower tuyere 9a, it is necessary to determine whether or not the raceway is formed according to the amount of waste plastic blown. Oriented to coking.
[0042]
Next, an outline of the control flow of ηCO in the furnace according to the present invention will be described. The control of the present invention is summarized as the following (1) to (5).
(1) The average metal content (average M.Fe / T.Fe) is determined from the components contained in the composite waste in the multi-function melting furnace and the blending amount (use amount). When aiming for more efficient operation, radial section charging is implemented, but when this charging method is applied, the average metal content rate for the composite waste charged in the central part and the peripheral part respectively. Ask for.
[0043]
(2) The ηCO level range suitable for operation is specified from the average metal content (average M.Fe / T.Fe) of the charged waste and the C content in the composite waste. When the radial section charging method is applied, an appropriate ηCO is specified for each of the central part and the peripheral part.
[0044]
(3) Since the average gas flow rate (Nm / s) in the furnace is determined by the operating conditions of the melting furnace (a guide for the output), the coke bed height from the lower tuyere is set according to the fuel particle size used.
[0045]
(4) For the stock level, the stock level (the height of the charging surface from the lower tuyere) H (m) corresponding to the target ηCO is specified and set. In the case of adopting the radial section charging method, it is preferable to set the stock level separately for the central part and the peripheral part.
[0046]
(5) Regarding the fuel ratio, in addition to the operating conditions including furnace body heat dissipation (kcal / h), target output (t / d), the type and quality of composite waste, etc. If the target ηCO shown in Fig. 2 is determined, the fuel ratio (kg / t) level is obtained from the heat / material balance. Finally, fine adjustment of the lower tuyere air volume and fine adjustment of the stock level are performed. Operate to maintain target ηCO level. When adopting the radial section charging method, the fuel ratio is set separately for each of the central part and the peripheral part.
[0047]
Next, it will be described that changing the charging height (stock level) in the melting furnace of the charging material composed of composite waste and fuel is effective for ηCO control.
As for the stock level, for example, in a cupola operation that uses a large-diameter casting coke and melts iron scraps and casting scraps, the height from the lower tuyere to the stock level (H) / furnace diameter (D ) = 4-5, however, there are no studies on the stock level for multi-functional melting furnaces using small-diameter coke such as blast furnace coke and using waste plastic as fuel. Therefore, a stock level change test was conducted under the condition of using a large amount of composite waste, and the relationship with exhaust gas ηCO was organized in FIG.
[0048]
According to the test results using a multi-function melting furnace with hearth diameter D = 1.4m, by setting H / D ≦ 3 as small as possible, it can be maintained high as exhaust gas ηCO> 50%, and by increasing the stock level It has been found that the exhaust gas ηCO can be reduced.
This is because if the stock level is increased, the heat transfer from the gas to the raw fuel will be good, and the preheating and temperature rise of the fuel will proceed from the top. As a result, the solution loss reaction region of the following formula (1) expands to the top of the furnace. Therefore, as a result, the consumption of C increases, which suggests that ηCO decreases.
C + CO ₂ = 2CO (1)
Thus, the change of the stock level has a role of controlling the rate of temperature rise of the raw fuel in the furnace, and becomes a control means for the exhaust gas ηCO.
[0049]
Next, it will be described that adjusting the height of the coke bed in the lower part of the multi-function melting furnace, and further changing the air flow rate, tuyere diameter, and tuyere protruding position are effective for ηCO control.
FIG. 5 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. 5, oxygen in the air blown from the tuyere and enriched oxygen burn with coke in the reaction of the following formula (2) to generate CO ₂ and complete combustion at the site where O ₂ disappears. It reaches. This part has the highest gas temperature, and above this, the endothermic reaction (1) of the solution reaction proceeds, ηCO decreases, and the gas temperature also decreases.
C + O ₂ → CO ₂ (2)
[0050]
When the coke particle size is reduced, the burning rate of the equation (2) is increased, and the portion of the maximum gas temperature (O ₂ = 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, as shown in FIG. 6, the overall ηCO in the furnace becomes higher than when the flow rate is low. Protruding the lower 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 rate. 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.
[0051]
Next, the combined waste treatment method using the radial sorting and charging method is effective for operation stability and low fuel ratio operation, and efficient operation is possible regardless of the type and particle size of the composite waste. The operation method for directing efficient operation according to the characteristics of the composite waste and the fuel will be described.
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. This is a separation method using Fe, and one is a separation method according to the particle size of the composite waste.
[0052]
First, it will be explained 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 separation can be made according to the size of Fe, preferably, composite waste having a high metal content, for example, composite waste using a large amount of metal material such as some washing machines, etc. is charged in the center of the furnace. Composite waste with a low content, for example, plastic parts / members after decomposition and crushing, are charged into the furnace periphery. The reason why the composite waste with a low metal content is charged in the periphery of the furnace and the composite waste with a high metal content is charged in the furnace center is to make it easy to control the height of the coke bed in the furnace center. That is, to ensure the central gas flow and to aim at low fuel ratio operation.
[0053]
When oriented to this operation, the lower 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 lower 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.
[0054]
The reason why the lower tuyere is set at the boundary between the center and the peripheral part of the furnace is that the air blown from the lower 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.
[0055]
In this operation, the appropriate air volume at the lower tuyere is determined by the coke bed height. As described above, the coke bed height varies depending on the coke particle size, the gas flow rate in the furnace, etc., but when the coke bed upper end level is set at the optimum position (ηCO> 90%), the air blown from the lower tuyere is not It becomes unnecessary. When 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 lower tuyere, and ideal operation is possible with respect to the furnace center.
[0056]
Next, it will be described that the charging method of mixing with fuel when the composite waste having a low metal content is charged into the periphery of the furnace is efficient.
If the operation with a high ηCO can be directed, an operation with a low fuel ratio is possible. However, when the composite waste with a low metal content contains a large amount of iron oxide, an experiment was conducted to reduce it under the condition of ηCO> 30%. Under conditions that do not mix with coke, the reduction reaction does not proceed, causing smelting reduction that adversely affects operation at high temperatures. On the other hand, even if composite waste containing a lot of iron oxide and having a low metal content is mixed with coke and charged, it has a reduction rate improvement effect of at least 20%, compared with the case where it is not mixed with coke. It became clear by the examination result of the offline simulator. Moreover, since the composite waste which does not contain iron oxide with a low metal content contains a large amount of C, it can be used as a substitute for coke by charging it into the periphery.
[0057]
This means that in the operation of charging composite waste with a low metal content, the charging method mixed with fuel (small-diameter coke) has a low coke ratio compared to the operation without mixing with fuel (small-diameter coke). It shows that can be oriented.
[0058]
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.
[0059]
Therefore, as described above, by introducing a composite waste mainly having a high metal content into the furnace center, the operation becomes difficult to cause smelting reduction in the furnace center, and the coke bed in the furnace center is abnormally consumed. Suppress. 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.
[0060]
The installation position of the upper tuyere is appropriate depending on the operation parameters such as coke granularity and air flow, but basically the ηCO level at the lower tuyere is 65% <ηCO <90% Degree is a guide.
[0061]
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 point of the composite waste exists at 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.
[0062]
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.
In the present embodiment, when the steam is blown from the upper tuyere 9b for processing, the furnace top temperature is suppressed to 300 ° C. or lower, and efficient operation is possible.
[0063]
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 metal content of the composite waste and the coke particle 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 composite waste and fuel charged in each part is determined.

Ri: dimensionless boundary radius (−) between the central portion and the peripheral portion
Wm (c): Weight of waste charged in the center (kg / charge)
Wc (c): Fuel weight charged in the center (kg / charge)
Wm (p): Weight of waste to be charged in the surrounding area (kg / charge)
Wc (p): Weight of fuel to be charged in the surrounding area (kg / charge)
ρm (c): Bulk density (kg / m ³ ) of waste charged in the center
ρc (c): Bulk density of fuel charged in the center (kg / m ³ )
ρm (p): Bulk density (kg / m ³ ) of waste to be charged at the periphery
ρc (p): Bulk density (kg / m ³ ) of the fuel charged in the periphery
[0064]
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.
[0065]
Further, the low coke ratio operation is performed, and the tuyere air volume is set such that the upper tuyere air volume> the lower tuyere air volume. This is because the purpose of burning the waste char as much as possible is blown by the upper tuyere.
[0066]
Furthermore, waste plastic is blown in from the lower tuyere together with room temperature oxygen-enriched air. The reason why waste plastic is used in combination is to achieve low coke by using waste plastic as a fuel and using the combustion gas as a heat source.
[0067]
Moreover, as a result of considering the reduction of the amount of coke used, it has been found that the position where the waste plastic is blown greatly affects the role played by the waste plastic from the following.
FIG. 7 is a diagram illustrating an example of a change in ηCO in a coke bed when waste plastic is blown into a normal coke bed.
There are two forms of C consumption in coke or C in waste plastic:
C + O ₂ → CO ₂ (4)
C + CO ₂ → 2CO (5)
[0068]
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, coke needs to be reacted as much as possible in equation (4), but when it comes into contact with high-temperature CO ₂ in the absence of O ₂ , coke solution loss occurs due to reaction in equation (5), and coke is wasted. Will be consumed.
[0069]
Since the waste plastic has a higher burning rate than coke, when the waste plastic is blown into the coke bed, the disappearance position of O ₂ is lowered as compared with the case where the waste plastic is not blown. Therefore, even if waste plastic is blown into the coke bed under the condition that waste plastic is not blown, coke will be present above the disappearance position of O ₂ , reducing the coke consumption of equation (4). Even if it can, coke consumption will increase in equation (5), and as a result, waste plastic blowing will not be able to contribute to reduction of coke consumption.
[0070]
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 (5) is not performed in the coke bed, or the Coke in the coke reacted in the formula (5) is replaced with C in the waste plastic so as not to cause a coke solution loss. It is to be.
[0071]
The first method is to set the upper level of the coke bed at such a height that O ₂ blown from the lower tuyere disappears, taking into account the waste plastic, so that no coke exists in the area where O ₂ does not exist. The waste plastic is blown between the lower tuyere level and the coke bed upper end level. In this case, the waste plastic blowing position may be an arbitrary position including the lower tuyere as long as it is between the lower tuyere level and the coke bed upper end level.
[0072]
The second method is when the upper level of the coke bed is set above the height at which O ₂ blown from the lower tuyere disappears, taking into account the waste plastic. In this case, the waste plastic is placed at the lower tuyere level. And a coke bed upper end level, and waste plastic for causing a solution loss instead of coke is also blown into a coke bed upper region where O ₂ does not exist. In this case, the lower plastic waste blowing 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 stage or a plurality of stages. Further, the upper plastic waste blowing position may be any position between the O ₂ vanishing point level and the coke bed upper end level, and may be one or more. According to this method, the amount of waste plastic blown can be increased by the amount blown into the upper part.
[0073]
【Example】
FIG. 8 is a schematic diagram showing a configuration of an apparatus for carrying out the composite waste processing method of the present embodiment. As shown in the figure, in the multi-function melting furnace 1, composite waste such as waste home appliances is charged by a charging device (not shown). In this embodiment, the composite waste is dismantled and partially processed, or the entire waste is processed without being dismantled. The operating conditions of the multifunction melting furnace 1 are shown in Table 1 below. The Cu content in the hot metal discharged from the multi-function melting furnace 1 is removed, and the exhaust gas is combusted and cooled by the exhaust gas treatment device 15 through the cyclone 14 and discharged from the chimney 16.
[0074]
[Table 1]

As shown in Table 1, Examples 1-4 show the case where ηCO is controlled to 20%, and Examples 5-10 show the case where ηCO is controlled to 45%. Waste household appliances are charged 1000 kg each, and CR represents the coke ratio of each example. Room-temperature oxygen-enriched air with an oxygen enrichment 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 air volume is set so that the upper tuyere air volume (secondary tuyere air volume)> lower tuyere air volume (primary tuyere air volume). Steam blowing amount from the upper tuyeres, Examples 1 to 5 is 3 g / Nm ^3, Example 6 320 g / Nm ^3, Examples 7 and 8 is 460 g / Nm ^3, Example 9 550 g / Nm ³ Example 10 is 650 g / Nm ³ .
[0075]
In the treatment of the composite waste, since tar and the like are discharged, it is preferable to operate by controlling the temperature of the furnace top gas to 300 ° C or more as much as possible, and more preferably in the range of 300 ° C to 450 ° C. Therefore, the conditions of Examples 1, 6 and 7 are particularly suitable.
[0076]
In Examples 1 to 10, a coke bed upper end level is set between the lower tuyere and the upper tuyere, and oxygen-enriched air having an oxygen enrichment of 8% or more is blown into the coke bed from the lower tuyere. By blowing steam from the upper tuyere, plastic contained in composite waste such as waste home appliances can be used as a fuel component, and stable operation of the multi-function melting furnace can be performed even if the amount of coke used is reduced I was able to.
[0077]
【The invention's effect】
As described above, according to the present invention, by setting specific processing conditions for the multi-function melting furnace, composite waste such as waste home appliances can be melted safely and efficiently without being disassembled and separated. In addition to being able to treat waste plastics, the coke consumption can be reduced and the melting furnace can be stably operated.
[Brief description of the drawings]
FIG. 1 is a multi-function melting furnace used in the composite waste disposal method of the present invention, (a) is a schematic diagram showing the overall configuration, and (b) is a schematic diagram showing the charging equipment installed in the center of the furnace. Schematic diagram showing the charging status, (c) is a schematic diagram showing the charging status of the charging device into the furnace periphery.
FIG. 2 is a schematic view showing an upper end level of a coke bed.
FIG. 3 is a schematic view showing a state of charging in the furnace radial direction.
FIG. 4 is an explanatory diagram showing a relationship with exhaust gas ηCO in a stock level change test.
FIG. 5 is an explanatory diagram showing an experimental result by an offline simulator of changes in coke bed height and ηCO.
FIG. 6 is an explanatory diagram showing a change in ηCO when the flow velocity is changed with the same coke particle size.
FIG. 7 is an explanatory diagram showing a change in ηCO when waste plastic is blown.
FIG. 8 is a schematic view showing the configuration of an apparatus for carrying out the composite waste processing method of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Multifunctional melting furnace 2 Charging apparatus 3 Bucket 4 Bell 5 Movable armor 6 Charging guide 7 Furnace body 8 Exhaust 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

Claims (2)

Coke is charged into a melting furnace having a two-stage air tuyer to form a coke bed, and then contains metal and plastic, and the total iron content [Total Fe] is 10% by mass <[Total Fe]. <80% by mass composite waste is charged together with coke, and when the composite waste is melted by drying, pyrolysis, combustion, and melting, the composite waste having a large diameter that is not disassembled in the center of the furnace , was charged with having a large metal content of the composite waste after grinding is mixed with a large diameter coke, small diameter having a small metal content of the composite waste after grinding broken into the furnace peripheral portion The coke bed upper end level is set between the upper tuyeres and the lower tuyere, the tuyere air volume is set to the upper tuyer air volume> lower tuyere air volume, From the lower tuyere to the coke bed lace With oxygen-enriched air enriched amount of 2% or more room temperature without forming a processing method of a composite waste, characterized in that blowing waste plastics. The method for treating composite waste according to claim 1, wherein steam is blown from the upper tuyere to cool the upper part of the furnace.

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