JP2004232988A

JP2004232988A - Method of controlling flue gas flow from electric melting furnace

Info

Publication number: JP2004232988A
Application number: JP2003023663A
Authority: JP
Inventors: Kichiji Matsuda; 吉司松田
Original assignee: Takuma Co Ltd
Current assignee: Takuma Co Ltd
Priority date: 2003-01-31
Filing date: 2003-01-31
Publication date: 2004-08-19
Anticipated expiration: 2023-01-31
Also published as: JP4028403B2

Abstract

<P>PROBLEM TO BE SOLVED: To stably operate an electric melting furnace and a flue gas treatment device on the downstream side thereof at all times even if the produced amount of flue gas in the electric melting furnace is varied by the change of the supplied amount and physical property values of materials to be molten supplied to the electric melting furnace in an electric melting furnace facility for melting and treating city refuse and refuse incinerated residue. <P>SOLUTION: The melting treatment facility using the electric melting furnace comprises the electric melting furnace for melting and treating city refuse and refuse incinerated residue, a secondary combustion chamber for burning flue gas from the electric melting furnace, a flue gas cooling device for cooling flue gas from the secondary combustion chamber, a flue gas treatment device for purifying flue gas from the flue gas cooling device, and an induction ventilator installed on the downstream side of the flue gas treatment device. An air supply port is formed between the secondary combustion chamber and the flue gas cooling device, and a flow detector for flue gas discharged into the atmosphere is installed near the induction ventilator. An air amount for cooling supplied to the air supply port through a flow controller is regulated by the detection signals of the flow detector, and the amount of flue gas circulating in the flue gas treatment device is held at any set value. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は都市ごみや都市ごみの焼却残滓等を溶融処理するアーク溶融炉やプラズマアーク溶融炉、抵抗式溶融炉等の電気溶融炉から排出されて排ガス処理装置へ流入する排ガス流量の制御方法に関するものであり、電気溶融炉の炉本体内で発生する排ガス量が変動しても、排ガス処理装置へは常に所定量の排ガスを流通させることにより、排ガス処理装置や電気溶融炉の運転をより安定したものに出来るようにした電気溶融炉からの排ガスの流量制御方法に関するものである。
【０００２】
【従来の技術】
都市ごみや都市ごみの焼却残滓等の溶融処理には、従前からアーク溶融炉やプラズマアーク溶融炉、抵抗式溶融炉等の電気溶融炉が多く利用されている。
図３は、従前の焼却灰等の溶融処理に広く利用されているプラズマアーク溶融炉の一例を示すものであり、炉本体１の天井壁に主電極２と補助電極３とが、また、炉本体１の底面に炉底電極４が夫々設けられており、直流電源装置５から主電極３と炉底電極４間へ直流電圧を印加して主電極２と溶融スラグＤ間にプラズマアーク６を発生させることにより、その発生熱によって炉本体１内へ供給されて来る焼却残滓等の被溶融物Ｃを順次溶融させて行く。尚、図３に於いてＤは焼却灰等の溶融スラグ（溶融物）、Ｂは金属等の溶融された溶融メタル、７は炉電電極４を構成する集電板、８は被溶融物Ｃの投入口、９は溶融スラグＤの隘流口、１０は溶融メタルＢの抜出孔、１２は主電極２を上・下位置調整可能に保持する主電極支持装置、１３は補助電極３を上・下動位置調整可能に保持する補助電極支持装置、１４は電力用配電盤である。
【０００３】
而して、都市ごみやその焼却残滓等の被溶融物が溶融した溶融スラグＤは、隘流口９を通して順次冷却用水槽（図示省略）内へ流下し、水冷スラグとして回収されて行く。
また、被溶融物Ｃの溶融に伴なって炉本体１内に発生した燃焼排ガスＧ_０は、隘流口９（又は図示されていないが、炉本体１の天井壁等に形成された排ガス排出口）等から炉本体１外へ誘引され、図４に示すように２次燃焼室１６で含有する可燃性成分を完全に燃焼させたあと、排ガス冷却装置１７、排ガス処理装置（集塵装置）１８、誘引通風機１９を経て煙突２０から大気中へ放出されて行く。
【０００４】
尚、図４に於いて４０はＯ_２濃度計、４１はＣＯ濃度計、４２は制御装置、４３は燃焼空気吹込み用ファン、４４は燃焼空気量制御ダンパ、４５は排ガス循環ファンであり、２次燃焼室１６への燃焼用空気の供給量制御や炉本体１内に残留する未燃カーボン量の排出制御が行なわれている。
尚、上記の如き電気溶融炉Ａの構成や被溶融物Ｃの定常的な溶融運転及び排ガス処理装置の運転操作等は公知の技術であるため、ここではその詳細な説明を省略する。
【特許文献１】
特開２００１−５０５２８号公報
【特許文献２】
特開平８−１２１７３９号公報
【特許文献３】
特開平８−９４０５９号公報
【０００５】
【発明が解決しようとする課題】
上記従前のプラズマアーク溶融炉やアーク溶融炉、抵抗式溶融炉等の電気溶融炉Ａは、焼却残滓等の被溶融物Ｃを安定に溶融処理することができ、優れた実用的効用を有するものである。
しかし、従前の溶融炉にも解決すべき問題が多く残されており、その中でも前記炉本体１内で発生する排ガス量が変動することにより、炉本体１の圧力や温度等が変動したり、排ガス処理装置へ流入する排ガス量の変動によってその安定した運転が困難になると云う点が、解決を急ぐ問題として残されている。
【０００６】
例えば、プラズマアーク溶融炉でごみ焼却残滓（焼却灰）を溶融処理する場合、焼却灰中に可燃物が存在していると、焼却灰が溶湯内へ溶け込むときに可燃物が燃焼することにより、燃焼排ガスＧ_０が発生する。このとき、焼却灰内の可燃物含有量が略一定で、しかも焼却灰の供給が一定量で連続的に行なわれる場合には、溶融炉本体内で発生する排ガス量は殆んど変動せず、その結果溶融炉本体内の圧力や温度等も比較的安定したものとなる。
【０００７】
しかし、実際の電気溶融炉の運転に於いては、供給されて来る焼却灰の性状や物性は常に変動し、可燃物の含有量も不同である。また、溶融炉本体１内への焼却灰の供給を連続的に行なっても、実際灰の溶融は間欠的になってしまうケースの方が多い。
その結果、必然的に溶融炉本体１内で発生する燃焼排ガスＧ_０の量が変動することになり、これが原因となって溶融炉本体１内の圧力や温度が変動したり、或いは２次燃焼室１６や排ガス処理装置１８への排ガスＧの流入量が変動して、２次燃焼や排ガス処理が不安定になる。
【０００８】
例えば、容量９４００ＫＶＡ、被処理物の処理量７０ｔ／日、被溶融物Ｃが複数のごみ焼却炉からのごみ焼却残滓（焼却灰）であるプラズマアーク溶融炉に於いては、電気溶融炉の定常運転時に於ける溶融炉本体１内からの燃焼排ガスＧ_０の排出量は、通常１５００Ｎｍ^３／Ｈｒ〜４０００Ｎｍ^３／Ｈｒの範囲に亘って変動し、これによって溶融炉本体１内の圧力や温度が−５ｍｍＨｇ〜＋５ｍｍＨｇ及び８００℃〜１４００℃に亘って変動することが経験的に判っている。
【０００９】
本発明は、従前の都市ごみやごみ焼却残滓を溶融処理するための電気溶融炉に於ける上述の如き問題、即ち▲１▼溶融炉本体１内で発生する燃焼排ガスＧ_０の量が変動することにより、溶融炉本体１内の圧力や温度が変動し、これによって下流側の排ガス処理装置１８の運転が不安定になるのを防止することを発明の主たる目的とするものであり、溶融炉本体１内で発生する燃焼排ガスＧ_０の量が変動したとしても、排ガス処理装置１８に於いて常に安定した排ガス処理を行ない得るようにした電気溶融炉の排ガス流量制御方法を提供するものである。
【００１０】
【課題を解決するための手段】
請求項１の発明は、都市ごみやごみ焼却残滓等を溶融処理する電気溶融炉と、電気溶融炉からの排ガスを燃焼させる２次燃焼室と、２次燃焼室からの排ガスを冷却する排ガス冷却装置と、排ガス冷却装置からの排ガスを清浄化する排ガス処理装置と、排ガス処理装置の下流側に設けた誘引通風機とを備えた電気溶融炉を用いた溶融処理設備に於いて、前記２次燃焼室と排ガス冷却装置との間に空気供給口を設けると共に、誘引通風機の近傍に大気中へ排出する排ガスの流量検出器を設け、当該流量検出器の検出信号により流量制御器を介して前記空気供給口へ供給する冷却用空気量を調整し、前記排ガス処理装置内を流通する排ガス量を任意の設定値に保持する構成としたことを発明の基本構成とするものである。
【００１１】
請求項２の発明は、請求項１の発明に於いて、空気供給口へ供給する冷却用空気を、溶融炉本体冷却した後の空気又は新鮮空気若しくは前記両者を混合した空気とするようにしたものである。
【００１２】
請求項３の発明は、請求項１の発明に於いて、排ガスの流量検出器を誘引通風機の下流側に設けるようにしたものである。
【００１３】
【発明の実施の形態】
以下、図面に基づいて本発明の実施形態を説明する。
図１は、本発明の実施に使用するプラズマアーク溶融炉の概要を示すものであり、プラズマアーク溶融炉自体の構成は、従前のプラズマアーク溶融炉の場合と略同一である。また、本実施形態では発明の実施に使用する電気溶融炉としてプラズマアーク電気溶融炉を挙げているが、溶融炉としては如何なる型式の電気溶融炉であってもよいことは勿論である。
更に、図２は、本発明に係る電気溶融炉からの排ガス流量制御方法を実施した電気溶融炉設備の全体構成図であり、電気溶融炉としては、図１のプラズマアーク溶融炉が用いられている。
【００１４】
前記図１に於いて、Ａは電気溶融炉、Ｄは溶融スラグ、Ｂは溶融メタル、Ｃは被溶融物、Ｇ_０は燃焼排ガス、１は炉本体、２は主電極、３は補助電極、４は炉底電極、５は直流電源装置、６はプラズマアーク、７は集電板、８は被溶融物投入口、９は溶融スラグＤの隘流口、１０は溶融メタルの抜出孔、１１は排ガス排出口、１２は主電極支持装置、１３は補助電極支持装置、１４は電力用配電盤であり、主電極２は直流電源装置５の−極に、補助電極３及び炉底電極４を形成する集電板７は＋極に夫々接続されている。
【００１５】
また、前記図２に於いて、１５は被溶融物（焼却灰）供給装置、１６は２次燃焼室、１７は排ガス冷却装置（減温塔）、１８は排ガス処理装置（濾過式集塵器）、１９は誘引通風機、１９ａは誘引通風機モータの速度制御装置、２０は煙突、２１は排ガス冷却用空気送風機、２１ａは送風機モータの速度制御装置、２２、２３、２４、２５はダンパ装置、２６は圧力検出器、２７、２８、２９は温度検出器、３０は排ガスの流量検出器、３１は排ガス流量制御器、３２、３３、３４は温度制御器、３５は通路開度制御器、３６は圧力制御器である。
【００１６】
図１及び図２を参照して、被溶融物供給装置１５により被溶融物投入口８を通して炉本体１内へ供給された焼却灰等の被溶融物Ｃは、溶融炉本体１内の溶融スラグＤ上へ落下し、溶融スラグＤの熱やプラズマアーク６の発生熱により順次溶融されると共に、隘流口９を通して溶融スラグＤが冷却水槽（図示省略）内へ流下して、水砕スラグが形成される。
【００１７】
一方、被溶融物Ｃ内に含有されている固定炭素等の可燃物は、前述の通り温度が約１７００℃の溶融スラグＤ等による加熱により燃焼し、溶融炉本体１内の上部空間内には燃焼排ガスＧ_０が発生する。尚、溶融炉本体１内の内圧は圧力検出器２６及び圧力制御器３６を介して溶融炉用誘引通風機１９の回転速度や誘引通風機入口側のダンパ装置２２の開度調整を行なうことにより、所定の設定圧（
ｍｍＨｇ）に保持されている。
【００１８】
前記溶融炉本体１内に発生した燃焼排ガスＧ_０は、溶融炉用の誘引通風機１９の誘引作用により排ガス排出口１１を通して２次燃焼室１６内へ導入され、ここで２次燃焼用空気ａ_１が混入されることにより、燃焼排ガスＧ_０内に残留する可燃物等が２次燃焼される。尚、２次燃焼室１６内の燃焼温度は、温度検出器２７及び温度制御器３４を介してダンパ装置２５の開度調整をし、２次燃焼用空気ａ_１の供給量を調整したり、補助燃料（図示省略）の供給量を調整することにより、所定の設定温度（約１０００℃）に制御されている。
【００１９】
２次燃焼室１６から排出された排ガスＧは、排ガス通路３７を通して排ガス冷却装置（減温塔）１７へ導入され、噴霧水（図示省略）等の噴霧により約２００℃の温度にまで減温される。
【００２０】
また、排ガス冷却装置１７内で所定の温度にまで減温された排ガスＧは、冷却用送風機２１から外気温度の冷却用空気ａ_２が混入されることにより所定の温度（約１８０℃〜２００℃）に調整され、排ガス処理装置１８で濾過集塵されることにより浄化される。
更に、前記排ガス処理装置１８により清浄化された排ガスＧは、誘引通風機１９を介して煙突２０へ排出され、大気中へ放散されて行く。
【００２１】
前記２次燃焼室１６と排ガス冷却装置１７との間（ここでは例として排ガス通路３７）には、溶融炉本体１の冷却用空気送風機３８からの冷却用空気ａ_３を混入する空気供給口３９が設けられており、ダンパ装置２４により適宜の流量に調整された冷却用空気ａ_３が、前記空気供給口３９から排ガスＧ内へ混入される。
【００２２】
即ち、本発明に於いては、前記誘引通風機１９から煙突２０へ排出される排ガスＧの流量が流量検出器３０により常時検出されており、排ガスＧの流量が設定値から外れた場合には、排ガス流量制御器３１からの制御信号により前記空気供給口３９の入口側に設けたダンパ装置２４の開度が調整される。その結果、排ガスＧ内へ供給される溶融炉本体冷却用空気送風機３８からの冷却用空気ａ_３の混入量が調整され、煙突２０へ排出する排ガス流量がほぼ設定値に保持される構成となっている。
【００２３】
前記空気供給口３９へ供給される冷却用空気ａ_３は、溶融炉本体１の空冷ジヤケット１ａ内を通過して約１００℃に加温された空気ａ_３又は新鮮な低温の外気若しくは加温された空気に適宜量の新鮮外気を混入して約５０℃〜８０℃とした空気ａ_３の何れでもよい。
【００２４】
また、前記図２に於いては排ガスの流量検出器３０を誘引通風機１９の排ガス出口側に設けているが、当該検出器３０を誘引通風機１９の入口側のダンパ装置２２の下流側に設けても良いことは勿論である。
【００２５】
前記の従来例との対比のために、容量９４００ＫＶＡ、被処理量７０ｔ／日、被処理物Ｃがごみ焼却残滓（焼却灰）のプラズマアーク溶融炉を用いた電気溶融処理設備に於いて、本願発明を実施した場合と実施をしない場合のケースについて、溶融炉本体１内の圧力変動幅、排ガス処理装置１８の下流側の排ガス温度変動幅を夫々調査した。夫々の変動幅は電気溶融炉を２４時間ほぼ同一の条件下で連続運転をした場合の、運転時間中の最大変動値を示すものである。尚、温度制御器３２、３３、３４、圧力制御器３６及び開度制御器３５による各制御が（Ａ）、（Ｂ）両者の運転時に、同一の条件下で作動されていることは勿論である。
【００２６】
【表１】

【００２７】
上記（Ａ）及び（Ｂ）欄に記載の各変動幅の対比からも明らかなように、本願発明を実施した場合には、本願発明を実施しない場合に比較して、炉本体１内の圧力変動や以後の排ガス温度変動が大幅に安定することが判る。
【００２８】
【発明の効果】
本発明に於いては、電気溶融炉からの排ガスの２次燃焼室とその下流側の排ガス冷却装置との間に空気供給口を設けると共に、排ガス流通経路の最下流に設けた誘引通風機の近傍に排ガスの流量検出器を設け、当該流量検出器の検出値に基づいて、前記空気供給口から排ガス内へ混入する冷却用空気量を調整することにより、煙突より外部へ排出する排ガスの流量を常に設定値に保持する構成としている。
その結果、電気溶融炉本体内へ供給される被溶融物（焼却灰等）の性状や物性値、或いは供給量等が変動して、溶融炉本体内で発生する排ガス量が大きく変動しても、排ガス冷却装置の下流側には常に一定流量の排ガスが流通することになり、排ガス処理装置の作動が安定化するだけでなしにその運転制御も容易となり、ひいては電気溶融炉そのものの運転が安定化することになる。
本発明は上述の通り優れた実用的効用を奏するものである。
【図面の簡単な説明】
【図１】本発明の実施に使用する電気溶融炉（プラズマアーク溶融炉）の全体構成を示す断面概要図である。
【図２】本発明の電気溶融炉から排ガス流量制御方法を実施した電気溶融炉設備の全体構成図である。
【図３】従前のプラズマアーク溶融炉の断面概要図である。
【図４】従前の電気溶融炉を用いた焼却灰溶融処理設備の構成図である。
【符号の説明】
Ａは電気溶融炉、Ｄは溶融スラグ、Ｂは溶融メタル、Ｃは被溶融物、Ｇ_０は排ガス、Ｇ_０は燃焼排ガス、ａ_１は２次燃焼用空気、ａ_２・ａ_３は冷却用空気、１は炉本体、１ａは空冷ジヤケット、２は主電極、３は補助電極、４は炉底電極、５は直流電源装置、６はプラズマアーク、７は集電板、８は被溶融物投入口、９は溶融スラグＤの隘流口、１０は溶融メタルの抜出孔、１１は排ガス排出口、１２は主電極支持装置、１３は補助電極支持装置、１４は電力用配電盤、１５は被溶融物供給装置、１６は２次燃焼室、１７は排ガス冷却装置（減温塔）、１８は集塵装置（濾過式集塵器）、１９は誘引通風機、１９ａは誘引通風機モータの速度制御装置、２０は煙突、２１は冷却用空気送風機、２１ａは送風機モータの速度制御装置、２２・２３・２４・２５はダンパ装置、２６は圧力検出器、２７・２８・２９は温度検出器、３０は排ガスの流量検出器、３１は排ガス流量制御器、３２・３３・３４は温度制御器、３５は通路開度制御器、３６は圧力制御器、３７は排ガス通路、３８は溶融炉本体冷却用空気送風機、３９は空気供給口である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for controlling the flow rate of exhaust gas discharged from an electric melting furnace such as an arc melting furnace, a plasma arc melting furnace, or a resistance melting furnace for melting and processing municipal solid waste and incineration residues of municipal solid waste, and flowing into an exhaust gas treatment device. Even if the amount of exhaust gas generated in the furnace body of the electric melting furnace fluctuates, the operation of the exhaust gas treatment device and the electric melting furnace is more stable by always flowing a predetermined amount of exhaust gas to the exhaust gas treatment device. The present invention relates to a method for controlling the flow rate of exhaust gas from an electric melting furnace, which is made possible.
[0002]
[Prior art]
Electric melting furnaces such as arc melting furnaces, plasma arc melting furnaces, and resistance melting furnaces have been widely used for melting treatment of municipal waste and incineration residues of municipal waste.
FIG. 3 shows an example of a plasma arc melting furnace widely used in the conventional melting treatment of incinerated ash and the like. A main electrode 2 and an auxiliary electrode 3 are provided on a ceiling wall of a furnace main body 1 and a furnace. Furnace bottom electrodes 4 are provided on the bottom surface of the main body 1, respectively, and a DC voltage is applied between the main electrode 3 and the furnace bottom electrode 4 from a DC power supply 5 to generate a plasma arc 6 between the main electrode 2 and the molten slag D. By generating it, the material to be melted C such as incineration residue supplied into the furnace body 1 by the generated heat is sequentially melted. In FIG. 3, D is a molten slag (melt) such as incineration ash, B is a molten metal such as a metal, 7 is a current collector plate constituting the

furnace electrode

4, and 8 is a material C to be melted. , 9 is a bottleneck of molten slag D, 10 is an outlet for molten metal B, 12 is a main electrode support device that holds the main electrode 2 so that the upper and lower positions can be adjusted, and 13 is an auxiliary electrode 3 An auxiliary electrode support device 14 that holds the upper and lower movement positions adjustable is a power switchboard.
[0003]
Thus, the molten slag D in which the material to be melted such as municipal solid waste and its incineration residue is melted flows down into a cooling water tank (not shown) sequentially through the bottleneck opening 9 and is collected as water-cooled slag.
Further, the combustion exhaust gas G ₀ that occur is accompanied furnace body 1 to the melting of the melt C is not隘流opening 9 (or illustrated, the exhaust gas is formed in the ceiling wall or the like of the furnace body 1 exhaust 4), the combustible components contained in the secondary combustion chamber 16 are completely burned as shown in FIG. 4, and then the exhaust gas cooling device 17 and the exhaust gas treatment device (dust collection device) 18. The air is released from the chimney 20 to the atmosphere via the induction ventilator 19.
[0004]
In FIG. 4, reference numeral 40 denotes an O ₂ concentration meter, 41 denotes a CO concentration meter, 42 denotes a control device, 43 denotes a combustion air blowing fan, 44 denotes a combustion air amount control damper, and 45 denotes an exhaust gas circulation fan. The control of the supply amount of combustion air to the secondary combustion chamber 16 and the discharge control of the amount of unburned carbon remaining in the furnace main body 1 are performed.
The configuration of the electric melting furnace A, the steady melting operation of the material to be melted C, the operation of the exhaust gas treatment device, and the like are well-known techniques, and thus detailed description thereof is omitted here.
[Patent Document 1]
JP 2001-50528 A [Patent Document 2]
Japanese Patent Application Laid-Open No. 8-12139 [Patent Document 3]
JP-A-8-94059
[Problems to be solved by the invention]
The electric melting furnace A such as the above-mentioned conventional plasma arc melting furnace, arc melting furnace, resistance melting furnace, etc., can stably melt a material C to be melted, such as incineration residues, and has excellent practical utility. It is.
However, there are still many problems to be solved in the conventional melting furnace. Among them, the amount of exhaust gas generated in the furnace body 1 fluctuates, so that the pressure and temperature of the furnace body 1 fluctuate, The point that the stable operation becomes difficult due to fluctuations in the amount of exhaust gas flowing into the exhaust gas treatment device remains as a problem that is urgently solved.
[0006]
For example, when melting incineration residue (incineration ash) in a plasma arc melting furnace, if there is combustible material in the incineration ash, the combustible material burns when the incineration ash melts into the molten metal, the combustion exhaust gas _{G 0} is generated. At this time, when the combustible material content in the incineration ash is substantially constant and the incineration ash is supplied continuously at a constant amount, the amount of exhaust gas generated in the melting furnace main body hardly fluctuates. As a result, the pressure, temperature and the like in the melting furnace main body become relatively stable.
[0007]
However, in the actual operation of the electric melting furnace, the properties and properties of the supplied incineration ash are constantly fluctuating, and the contents of combustibles are also different. Further, in many cases, even if the incineration ash is continuously supplied into the melting furnace main body 1, the actual melting of the ash is intermittent.
As a result, the amount of combustion exhaust gas G ₀ that occur inevitably melting furnace main assembly 1 is varied, which is or fluctuating pressure and temperature of the melting furnace main body 1 is caused, or secondary combustion The amount of exhaust gas G flowing into the chamber 16 and the exhaust gas treatment device 18 fluctuates, and secondary combustion and exhaust gas treatment become unstable.
[0008]
For example, in a plasma arc melting furnace having a capacity of 9400 KVA, a processing amount of a processing target of 70 t / day, and a melting target C as refuse incineration residue (incineration ash) from a plurality of refuse incinerators, a stationary state of the electric melting furnace emissions of the combustion exhaust gas _{G 0} from in the melting furnace main assembly 1 during operation is typically varied over a range of 1500Nm ^³ / Hr~4000Nm ³ / Hr, which pressure and temperature of the melting furnace main body 1 by the It has been empirically found to vary from −5 mmHg to +5 mmHg and from 800 ° C. to 1400 ° C.
[0009]
The present invention, conventional urban Gomiyagomi incineration residue to in above-mentioned problems in an electric melting furnace for melting processes, i.e. ▲ 1 ▼ the amount of combustion exhaust gas G ₀ generated in the melting furnace main assembly 1 fluctuates Accordingly, it is a main object of the present invention to prevent the pressure and temperature in the melting furnace main body 1 from fluctuating, thereby preventing the operation of the downstream exhaust gas treatment device 18 from becoming unstable. even the amount of combustion exhaust gas G ₀ generated in the main body 1 is changed, there is provided an exhaust gas flow rate control method as the electric melting furnace may perform always stable exhaust gas treatment at the exhaust gas treating apparatus 18 .
[0010]
[Means for Solving the Problems]
The invention according to claim 1 is an electric melting furnace for melting and processing municipal waste and refuse incineration residues, a secondary combustion chamber for burning exhaust gas from the electric melting furnace, and exhaust gas cooling for cooling exhaust gas from the secondary combustion chamber. A melting treatment facility using an electric melting furnace having a device, an exhaust gas treatment device for purifying exhaust gas from an exhaust gas cooling device, and an induction ventilator provided on the downstream side of the exhaust gas treatment device. An air supply port is provided between the combustion chamber and the exhaust gas cooling device, and a flow rate detector for exhaust gas discharged into the atmosphere is provided near the induction ventilator. The basic configuration of the present invention is that the amount of cooling air supplied to the air supply port is adjusted so that the amount of exhaust gas flowing through the exhaust gas treatment device is maintained at an arbitrary set value.
[0011]
According to a second aspect of the present invention, in the first aspect of the invention, the cooling air supplied to the air supply port is air after cooling the melting furnace main body, fresh air, or a mixture of the two. Things.
[0012]
According to a third aspect of the present invention, in the first aspect, the exhaust gas flow rate detector is provided on the downstream side of the induction ventilator.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an outline of a plasma arc melting furnace used for carrying out the present invention, and the configuration of the plasma arc melting furnace itself is substantially the same as that of the conventional plasma arc melting furnace. Further, in this embodiment, a plasma arc electric melting furnace is used as an electric melting furnace used for carrying out the present invention, but it goes without saying that any type of electric melting furnace may be used as the melting furnace.
Further, FIG. 2 is an overall configuration diagram of an electric melting furnace facility in which the method for controlling the flow rate of exhaust gas from the electric melting furnace according to the present invention is used. As the electric melting furnace, the plasma arc melting furnace of FIG. 1 is used. I have.
[0014]
In FIG 1, A is an electric melting furnace, D is the molten slag, B is molten metal, C is the melt, G ₀ is flue gas, 1 furnace body, 2 is a main electrode, 3 an auxiliary electrode, 4 is a furnace bottom electrode, 5 is a DC power supply, 6 is a plasma arc, 7 is a current collector, 8 is an inlet for a material to be melted, 9 is a bottleneck for molten slag D, 10 is a hole for extracting molten metal, Reference numeral 11 denotes an exhaust gas outlet, 12 denotes a main electrode support device, 13 denotes an auxiliary electrode support device, 14 denotes a power switchboard, and the main electrode 2 connects the negative electrode of the DC power supply 5 to the auxiliary electrode 3 and the furnace bottom electrode 4. The current collectors 7 to be formed are connected to the positive poles, respectively.
[0015]
In FIG. 2, reference numeral 15 denotes a melted material (incineration ash) supply device, 16 denotes a secondary combustion chamber, 17 denotes an exhaust gas cooling device (reducing tower), and 18 denotes an exhaust gas treatment device (filter-type dust collector). ), 19 are an induction ventilator, 19a is a speed control device of an induction ventilator motor, 20 is a chimney, 21 is an air blower for exhaust gas cooling, 21a is a speed control device of a blower motor, 22, 23, 24 and 25 are damper devices. , 26 are pressure detectors, 27, 28, 29 are temperature detectors, 30 is an exhaust gas flow rate detector, 31 is an exhaust gas flow rate controller, 32, 33, 34 are temperature controllers, 35 is a passage opening degree controller, 36 is a pressure controller.
[0016]
With reference to FIGS. 1 and 2, a melt C such as incineration ash supplied into the furnace main body 1 through the melt input port 8 by the melt supply device 15 is supplied to the molten slag in the melt furnace main body 1. D, the molten slag D is sequentially melted by the heat of the molten slag D and the heat generated by the plasma arc 6, and the molten slag D flows down into the cooling water tank (not shown) through the bottleneck opening 9, and the granulated slag is discharged. It is formed.
[0017]
On the other hand, combustibles such as fixed carbon contained in the material to be melted C are burned by heating with the molten slag D having a temperature of about 1700 ° C. as described above, and the upper space in the melting furnace body 1 is in the upper space. the combustion exhaust gas _{G 0} is generated. The internal pressure in the melting furnace main body 1 is controlled by adjusting the rotation speed of the induction fan 19 for the melting furnace and the opening of the damper device 22 on the inlet side of the induction fan through the pressure detector 26 and the pressure controller 36. , A predetermined set pressure (
mmHg).
[0018]
The melting furnace main body combustion exhaust gas G ₀ generated in the 1 is introduced through the exhaust gas discharge port 11 into the secondary combustion chamber 16 by the attraction action of the induced draft fan 19 for the melting furnace, wherein the secondary combustion air a _{by 1} is mixed, combustible materials such as remaining in the combustion exhaust gas G ₀ is secondary combustion. Incidentally, the combustion temperature in the secondary combustion chamber 16, the opening adjustment of the damper device 25 through the temperature detector 27 and the temperature controller 34, to adjust the supply amount of the secondary combustion air a _1, By adjusting the supply amount of the auxiliary fuel (not shown), the temperature is controlled to a predetermined set temperature (about 1000 ° C.).
[0019]
The exhaust gas G discharged from the secondary combustion chamber 16 is introduced into an exhaust gas cooling device (reducing tower) 17 through an exhaust gas passage 37, and is cooled down to a temperature of about 200 ° C. by spraying with spray water (not shown). You.
[0020]
Further, the exhaust gas G which has been cooled to a predetermined temperature in the exhaust gas cooling device 17 is cooled to a predetermined temperature (about 180 ° C. to 200 ° C.) by mixing cooling air a ₂ having an outside air temperature from the cooling blower 21. ) And purified by filtering and collecting in the exhaust gas treatment device 18.
Further, the exhaust gas G purified by the exhaust gas treatment device 18 is discharged to a chimney 20 via an induction ventilator 19 and is emitted to the atmosphere.
[0021]
Wherein the between the secondary combustion chamber 16 and the exhaust gas cooler 17 (the exhaust gas passage 37 as an example here), the melting furnace air supply port 39 for mixing the cooling air a ₃ from the cooling air blower 38 of the main body 1 is provided, the cooling air a ₃ adjusted to an appropriate flow rate by the damper device 24 is mixed from the air supply port 39 into the exhaust gas G.
[0022]
That is, in the present invention, the flow rate of the exhaust gas G discharged from the induction ventilator 19 to the chimney 20 is constantly detected by the flow rate detector 30, and when the flow rate of the exhaust gas G deviates from the set value, The opening of the damper device 24 provided on the inlet side of the air supply port 39 is adjusted by a control signal from the exhaust gas flow controller 31. Is a result, the adjusted mixing amount of the cooling air a ₃ from the melting furnace body cooling air blower 38 to be supplied into the exhaust gas G, a structure in which exhaust gas flow to be discharged to the chimney 20 is held substantially set value ing.
[0023]
The cooling air a ₃ supplied to the air supply port 39 is outside air or warm air a ₃ or fresh cold warmed to about 100 ° C. by passing through the melting furnace main body 1 of the air-cooled jacket inside 1a and appropriate amount of may be either air a ₃ which was about 50 ° C. to 80 ° C. by mixing fresh outside air into the air.
[0024]
In FIG. 2, the exhaust gas flow rate detector 30 is provided on the exhaust gas outlet side of the induction ventilator 19, but the detector 30 is located downstream of the damper device 22 on the entrance side of the induction ventilator 19. Of course, it may be provided.
[0025]
For comparison with the above-mentioned conventional example, the present invention is applied to an electric melting treatment facility using a plasma arc melting furnace in which a capacity of 9400 KVA, a treatment amount of 70 t / day, and a treatment object C is a refuse incineration residue (incineration ash). The pressure fluctuation width in the melting furnace main body 1 and the exhaust gas temperature fluctuation width on the downstream side of the exhaust gas treatment device 18 were examined for the case where the invention was implemented and the case where the invention was not implemented. Each fluctuation range indicates the maximum fluctuation value during the operation time when the electric melting furnace is continuously operated under substantially the same conditions for 24 hours. It should be noted that the respective controls by the temperature controllers 32, 33, and 34, the pressure controller 36, and the opening degree controller 35 are operated under the same conditions when both (A) and (B) are operated. is there.
[0026]
[Table 1]

[0027]
As is clear from the comparison of the respective fluctuation ranges described in the above (A) and (B) columns, the pressure in the furnace main body 1 is larger when the present invention is implemented than when the present invention is not implemented. It can be seen that the fluctuation and the subsequent fluctuation of the exhaust gas temperature are greatly stabilized.
[0028]
【The invention's effect】
In the present invention, an air supply port is provided between a secondary combustion chamber for exhaust gas from an electric melting furnace and an exhaust gas cooling device on the downstream side of the secondary combustion chamber. An exhaust gas flow rate detector is provided in the vicinity, and the amount of cooling air mixed into the exhaust gas from the air supply port is adjusted based on the detection value of the flow rate detector to thereby reduce the flow rate of the exhaust gas discharged from the chimney to the outside. Is always kept at the set value.
As a result, even if the properties and physical properties of the material to be melted (such as incinerated ash) supplied to the electric melting furnace main body or the supply amount fluctuate, the amount of exhaust gas generated in the melting furnace main body fluctuates greatly. A constant flow rate of exhaust gas always flows downstream of the exhaust gas cooling device, which not only stabilizes the operation of the exhaust gas treatment device, but also facilitates the operation control of the exhaust gas treatment device. It will be.
The present invention has excellent practical utility as described above.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the overall configuration of an electric melting furnace (plasma arc melting furnace) used for carrying out the present invention.
FIG. 2 is an overall configuration diagram of an electric melting furnace facility in which the method for controlling the flow rate of exhaust gas from the electric melting furnace of the present invention is performed.
FIG. 3 is a schematic sectional view of a conventional plasma arc melting furnace.
FIG. 4 is a configuration diagram of incineration ash melting treatment equipment using a conventional electric melting furnace.
[Explanation of symbols]
A electric melting furnace, D is the molten slag, B is molten metal, C is the melt, _{G 0} is the exhaust gas, _{G 0} is the flue gas, _{a 1}

secondary combustion

_air, _a 2 · a ₃ is for cooling Air, 1 is a furnace body, 1a is an air-cooled jacket, 2 is a main electrode, 3 is an auxiliary electrode, 4 is a furnace bottom electrode, 5 is a DC power supply, 6 is a plasma arc, 7 is a current collector, 8 is a material to be melted. Input port, 9 is a bottleneck of molten slag D, 10 is an outlet for molten metal, 11 is an exhaust gas outlet, 12 is a main electrode support device, 13 is an auxiliary electrode support device, 14 is a power distribution board, and 15 is a power distribution panel. A molten material supply device, 16 is a secondary combustion chamber, 17 is an exhaust gas cooling device (cooling tower), 18 is a dust collecting device (filtration type dust collector), 19 is an induction fan, and 19a is an induction fan motor. Speed control device, 20 is a chimney, 21 is a cooling air blower, 21a is a speed control device of a blower motor, 22 23, 24 and 25 are damper devices, 26 is a pressure detector, 27, 28 and 29 are temperature detectors, 30 is an exhaust gas flow detector, 31 is an exhaust gas flow controller, 32, 33 and 34 are temperature controllers, 35 is a passage opening controller, 36 is a pressure controller, 37 is an exhaust gas passage, 38 is an air blower for cooling the melting furnace body, and 39 is an air supply port.

Claims

From an electric melting furnace that melts municipal solid waste and incineration residue, etc., a secondary combustion chamber that burns exhaust gas from the electric melting furnace, an exhaust gas cooling device that cools exhaust gas from the secondary combustion chamber, and an exhaust gas cooling device An exhaust gas treatment device for purifying exhaust gas, and a melting treatment facility using an electric melting furnace provided with an induction ventilator provided downstream of the exhaust gas treatment device, wherein the secondary combustion chamber, the exhaust gas cooling device, An air supply port is provided between them, and a flow detector for exhaust gas discharged into the atmosphere is provided near the induction ventilator, and the exhaust gas is supplied to the air supply port via a flow controller by a detection signal of the flow detector. A method for controlling the flow rate of exhaust gas from an electric melting furnace, characterized in that the amount of cooling air is adjusted and the amount of exhaust gas flowing through the exhaust gas treatment device is maintained at an arbitrary set value.

2. The method for controlling the flow rate of exhaust gas from an electric melting furnace according to claim 1, wherein the cooling air supplied to the air supply port is air after cooling the melting furnace main body, fresh air or a mixture of the two. .

The method for controlling the flow rate of exhaust gas from an electric melting furnace according to claim 1, wherein the flow rate detector of the exhaust gas is provided downstream of the induction ventilator.