JP4061785B2 - Waste plastic treatment method in coke oven - Google Patents
Waste plastic treatment method in coke oven Download PDFInfo
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- JP4061785B2 JP4061785B2 JP27635799A JP27635799A JP4061785B2 JP 4061785 B2 JP4061785 B2 JP 4061785B2 JP 27635799 A JP27635799 A JP 27635799A JP 27635799 A JP27635799 A JP 27635799A JP 4061785 B2 JP4061785 B2 JP 4061785B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/141—Feedstock
- Y02P20/143—Feedstock the feedstock being recycled material, e.g. plastics
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
- Coke Industry (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、廃プラスチックを配合炭と一緒にコークス炉へ装入して熱分解する廃プラスチッの処理方法に関し、更には、コークス炉内で発生する廃プラスチックの熱分解残渣がコークス炉ガス吸引系および副生品中へキャリーオーバーされるのを防止して廃プラスチックを処理する方法に関する。
【０００２】
【従来の技術】
産業廃棄物および一般廃棄物として排出される廃プラスチックは、従来、主に焼却または埋め立てによる方法で処理されてきた。しかし、近年、環境保護および資源リサイクルの面から従来の処理方法の見直しが必要となり、新たな処理方法が種々検討されている。
【０００３】
その１にコークス炉を利用する方法がある。この方法として破砕または粒状化された廃プラスチックを配合炭に混合し、配合炭と共に乾留する過程で廃プラスチックを熱分解し、タール、軽油、その他ガス等として回収する方法が提案されている。
【０００４】
しかし、このように廃プラスチックを配合炭に混合する方法では、廃プラスチックの粒度が大きすぎたり混合比率が高い場合には、成品のコークス強度が低下することが知られている。そのため、高炉用コークスのように高強度が要求される場合には、廃プラスチックを粒径１ｍｍ程度に微粉砕する必要があって粉砕コストが高くなるほか、混合比率も１ｗｔ％以内にする必要があり、廃プラスチックを多量に処理することができないという欠点がある。
【０００５】
すなわち、上述した廃プラスチックを配合炭に混合してコークス炉で熱分解処理する方法では、石炭に混合する廃プラスチックが成品コークスの強度に影響を与える点が制約となっている。
【０００６】
そこで、成品コークスの強度に与える影響が少ない処理方法として、廃プラスチック類を配合炭に混合せずに、装入した配合炭の上部に装入する方法が提案されている。
【０００７】
例えば、特開平８−１５７８３４号公報には、コークス製造用装入炭を単独、または、廃プラスチックを０．１wt％〜１．０wt％配合してコークス炉に装入した後、専用のホッパーから炭化室の装入口を経由して前記装入炭の上部に廃プラスチックを装入して乾留し、乾留中に廃プラスチックを熱分解してタール、軽油、ガスとして回収する方法が提案されている。
【０００８】
この方法によれば、配合炭に混合する廃プラスチックは微粉砕する必要があるものの、混合割合が１ｗｔ％以内であるため成品コークスの強度に与える影響は少ない。また、コークス炉の装入炭上部に装入する廃プラスチックは成品コークスの強度に影響を与えないので、微粉砕する必要がないし、配合炭に混合する場合に比べて処理量も増加し得るという利点がある。
【０００９】
特に、同じ特開平８−１５７８３４号公報には、配合炭装入後から乾留終了までの間、コークス炉の炉頂空間部へ通じる専用の供給装置により廃プラスチックを継続的に供給する方法も提案されている。この方法によれば、廃プラスチックの処理量をさらに増加させることができる。
【００１０】
【発明が解決しようとする課題】
しかし、発明者らの検討によれば、廃プラスチックをコークス炉で熱分解すると、熱分解されて完全にガス化する場合は少なく、非常に軽い微粉末状の熱分解残渣が残ることが判明した。
【００１１】
そのため、特開平８−１５７８３４号公報に提案されている方法では、廃プラスチックを配合炭の上部に装入するため、この熱分解残渣が配合炭の乾留中に発生するコークス炉ガスにより搬送されて炭化室の炉壁に付着したり、炭化室外に搬送された場合には上昇管およびガス吸引管などに付着し、さらには、ガス吸引ラインを閉塞するという事態が発生するという問題がある。また、炭化室外に搬送された熱分解残渣が、副成品であるタールに混入して品質を低下させるという問題もある。
【００１２】
【課題を解決するための手段】
そこで、発明者らは多量の廃プラスチックを処理しても成品コークスの強度に影響を与えず、しかも、廃プラスチックの熱分解残渣が炭化室外へ搬送されることがない方法について種々検討を重ねた結果、つぎの発明に至った。
【００１３】
発明の第１の態様は、まず、廃プラスチックを０ｗｔ％〜１ｗｔ％の範囲で混合したコークス製造用のＤ１ 30/15 ９２以上となる配合炭Ａをコークス炭化室へ装入し、次いで、前記配合炭Ａを乾留する間に、前記配合炭Ａの上部に廃プラスチックを１ｗｔ％〜６０ｗｔ％の割合で混合した配合炭Ｂを装入して、前記配合炭Ａおよび配合炭Ｂを乾留してコークスとし、前記廃プラスチックを熱分解してコークス炉ガスおよび副生品として回収することを特徴とするコークスを製造し、合わせて廃プラスチックを処理する方法である。
【００１４】
発明の第２の態様は、廃プラスチックを０ｗｔ％〜１ｗｔ％の範囲で混合したコークス製造用のＤ１ 30/15 ９２以上となる配合炭Ａを炭化室へ装入し、つぎに、前記配合炭Ａの１次収縮後に、前記配合炭Ａの上部に廃プラスチックを１ｗｔ％〜６０ｗｔ％の割合で混合した配合炭Ｂを装入して、前記配合炭Ａおよび配合炭Ｂを乾留してコークス化するとともに、前記廃プラスチックを熱分解してコークス炉ガスおよび副生品として回収することを特徴とするコークスを製造し、合わせて廃プラスチックを処理する方法である。
【００１５】
上記の通り、最初に装入する配合炭Ａと２回目に装入する配合炭Ｂとに差別をつけ、配合炭Ａから製造されるコークスと配合炭 B から生成されるコークスが分離しやすいように配慮した。
【００１６】
【発明の実施の形態】
本発明において対象とする廃プラスチックは塩化ビニルを含まない廃棄物としてのプラスチックである。また、廃プラスチックが塩化ビニルを含む場合には脱塩素処理後の廃プラスチックである。この理由は塩化ビニルは分解に際して塩素ガスを発生し、コークス炉のガス吸引設備を腐食させるためである。
【００１７】
なお、炭化水素系であればプラスチックに限らず廃タイヤなどのゴム類でも処理できる。このような廃プラスチックのコークス炉の乾留における分解挙動を調査するため、発明者らは内径５ｃｍ、長さ２５０ｃｍの鋼管の一端を封じてその中へ廃プラスチック粒子を充填し、この鋼管を装入孔から垂直に炭化室内に挿入し、廃プラスチックの乾留状況を調査した。
【００１８】
その結果、鋼管内の廃プラスチックは熱分解されるもののガス化して完全に消失せずに、粒径が最大１ｍｍ以下の黒色微粉末状の熱分解残渣が残ることが判明した。なお、この熱分解残渣の重量は、はじめに充填した廃プラスチック粒子重量の約２０〜３０ｗｔ％であった。また、嵩比重は０．２程度で非常に軽いものである。
【００１９】
本願発明は、上記の知見に基づいてなされたもので、配合炭を高炉に装入できる高強度コークス製造のための配合炭（以下、配合炭Ａという。）、例えば、コークスのＤＩ30/15が９２．０以上となる配合炭と、配合炭Ａに比べて目標品位を低下させた配合炭（以下、配合炭Ｂという。）、例えば強度目標ＤＩ30/15が８５．０以下である配合炭とに区別する。配合炭Ａは成品コークスの必要強度に応じた目標品位とし、一方、配合炭Ｂには廃プラスチックを多量に混合して配合炭Ａの上部に装入することにより、廃プラスチックを熱分解させ、発生する熱分解残渣が炭化室外へ搬送されるのを防止する。
【００２０】
通常、配合炭の嵩比重は０．７ｔ／ｍ3程度であり、それに対し、廃プラスチックの嵩比重は０．３５ｔ／ｍ3程度、また、廃プラスチックの熱分解残渣の嵩比重は前述したように０．２ｔ／ｍ3程度であって、廃プラスチックおよびその熱分解残渣の嵩比重は配合炭の嵩比重よりも小さい。
【００２１】
したがって、嵩比重の小さい廃プラスチックを嵩比重の大きい配合炭Ｂと混合することにより、廃プラスチック粒子および廃プラスチックの熱分解残渣がコークス炉ガスに随伴して炭化室外へ搬送されるのを防止することができる。
【００２２】
また、配合炭Ｂの目標品位を下げているので、配合炭Ｂが乾留されてできるコークスは低強度のコークスであるため、コークス炉から高炉へ搬送される途中の工程で破砕、粉化されて、自ずと配合炭Ａから製造される高強度コークスとは分離される。配合炭Ｂの強度目標は配合炭Ａの強度目標よりもＤＩ30/15が２以上、より望ましくは５から７程度低いことが両者から得られるコークスを分離する点から望ましい。以上が本発明の概要である。
【００２３】
以下、本願発明の実施の形態について具体的に説明する。
まず、配合炭Ａの品位について説明する。高炉用コークスを製造する場合、成品コークス強度目標は、例えば、ＤＩ30/15を９２以上、例えば９３．０が高炉用コークスとして望ましい。配合炭への廃プラスチックの混合率が１ｗｔ％増加するごとにコークス強度（ＤＩ30/15）が０．５〜１．０ポイント低下するので、コークス強度の目標が高い場合には、廃プラスチック混合率は１ｗｔ％以内とするのが好ましく、廃プラスチックを全く混合しない方がより好ましい。
【００２４】
ここで、コークス強度（ＤＩ30/15）は、ＪＩＳ K ２１５１で規定される回転ドラム強度であり、コークス試料を回転ドラム内で３０回転させた後の粒径１５ｍｍ以上の試料の重量割合を示すものである。また、配合炭Ａに混合する廃プラスチックの粒度は配合炭の粒度（−３ｍｍが８０ｗｔ％程度）に微粉砕されていることが好ましいが、廃プラスチックの微粉砕は技術的に難しいので、実際には１〜３ｍｍ程度であれば良い。
【００２５】
配合炭Ｂが乾留して生成するコークスは廃プラスチックを多量に混合するため強度が低くなるので、配合炭Ｂの品位は必ずしも配合炭Ａと同じである必要はない。むしろ、配合炭Ｂの品位を配合炭Ａの品位に対して大幅に下げた方が、配合炭Ａから製造される高強度コークスと配合炭Bから製造される低強度コークスとの分離がし易く、低強度コークスが高炉へ装入される危険が少なくなる。
【００２６】
例えば、配合炭Ａの強度目標をＤＩ30/15を９３．０に設定し、一方、配合炭Ｂの強度目標をＤＩ30/15を８４．０に設定すれば、配合炭Ｂから製造された低強度コークスは、窯出し工程、ＣＤＱによる冷却工程、および途中の搬送過程で粉化するので、篩い分け工程で殆ど篩下に分離されてしまう。
【００２７】
しかし、後述するように配合炭Ａに対し配合炭Ｂの割合を多くする場合は、配合炭Ｂから製造されるコークスの強度が低すぎると窯出しができなくなるので、炭化室に装入する配合炭の全量に対して配合炭Ｂの装入割合は１／３から１／２程度が望ましく、配合炭Ｂの強度目標は、少なくともＤＩ30/15を８０以上とすべきである。
【００２８】
また、配合炭Ｂへ混合する廃プラスチックの割合は、廃プラスチックの処理の観点から、少なくとも配合炭Aに混合する割合、即ち１ｗｔ％以上とすべきであるが、一方、配合炭Ｂの廃プラスチック混合割合が大き過ぎると、配合炭Ｂによる熱分解残渣の搬出防止効果が薄れるので、廃プラスチックの割合は６０ｗｔ％以内とすることが望ましい。
【００２９】
なお、配合炭Ｂへ混合する廃プラスチックは配合炭Ａに混合する廃プラスチックのように微粉砕されたものである必要はなく、各ホッパ出口、炭化室の装入口の大きさを勘案して決めれば良い。
【００３０】
また、廃プラスチックの処理量を増加する場合、配合炭Ａを通常の装入量より減装して、その分、配合炭Ｂを多く装入すればよい。しかし、配合炭Ｂの割合を炭化室の配合炭全体の１／３以上とする場合には、配合炭Ｂの目標強度をＤＩ30/15で８０以上に設定しないと窯出しの際に押し詰まりを生じて押し出し困難となる。
【００３１】
つぎに、配合炭Ｂの装入方法について説明する。
配合炭Ｂの装入には、既存の装炭車が使用できる。配合炭Aを減装する場合であれば、配合炭Ｂの装入時期は配合炭Ａの装入直後から乾留終了までの間であればいつでもよい。但し、配合炭Ａの乾留終了までに配合炭Ｂが乾留終了するように配合炭Ｂの装入時期を設定する必要がある。
【００３２】
また、既存の装炭車で配合炭Ａと配合炭Ｂを一度に装入することもできる。この場合には石炭塔の各石炭ホッパーから装炭車のチャージホッパーに、まず配合炭Aを所定量充填し、その上に配合炭Ｂを充填し、それを、チャージホッパーの下端から抜き出すと、炭化室には配合炭Ａとその上部に配合炭Ｂを一度に装入することができる。
【００３３】
また、配合炭Ａの減装ができない場合は、乾留過程で配合炭Aが１次収縮して上部空間が広がるので、配合炭Aの１次収縮後に配合炭Ｂを装入すれば、装入することができる。
【００３４】
一般的に、石炭は乾留過程で約６％の体積収縮を生じる１次収縮および２次収縮を起こす。１次収縮は配合炭装入後３０〜６０分経過するまでに生じ、２次収縮は１次収縮と乾留終了の間で起こる。しかし、２次収縮後に配合炭Ｂを装入したのでは規定時間内に配合炭Ｂの乾留が終了しないので、配合炭Ｂの装入時期としては、１次収縮後が好ましい。そこで、配合炭Ａを減装しない場合であれば、配合炭Ａが１次収縮して配合炭Ａの上部空間が拡張された後に、配合炭Ｂを装入できる。
【００３５】
配合炭Ａおよび配合炭Ｂから製造されたコークスは、乾留終了後に押出し機による窯出、ＣＤＱによる消火、整粒作業を経て高炉へ搬送されるが、配合炭Ｂから製造されたコークスは強度を低く設定しているので、搬送途中で粉化、細粒化して篩下の小粒コークスとして分離されるので、配合炭Ｂから製造された低強度コークスが高炉へ装入される心配は殆どない。なお、篩下として回収された小粒コークスは高炉用コークス以外の用途、例えば、焼結用の粉コークス等として使用される。
【００３６】
【実施例】
以下に、本願発明の実施例として、配合炭Ｂを配合炭Aと装炭車で一度に装入する場合（発明例１）と配合炭Ａの１次収縮後に装入する場合（発明例２）について説明する。発明例１および発明例２で使用した、商用の室炉式コークス炉寸法および配合炭Ａおよび配合炭Ｂの品位（強度目標値）ならびに各配合炭に混合した廃プラスチックの性状と混合比率をそれぞれ図１の表１に示す。
【００３７】
発明例１および発明例２とも、廃プラスチックはガス吸引系の腐食の原因となる塩素ガスを発生する塩化ビニル系のプラスチックを除いたもので、粒度範囲が概略１ｍｍ〜１０ｍｍの範囲に破砕されたものを準備し、篩目が３ｍｍの篩を用いて＋３ｍｍの粒度のものと、−３ｍｍの粒度のものに分けて使用した。配合炭Ａには−３ｍｍの廃プラスチックを１ｗｔ％混合し、また、配合炭Ｂには＋３ｍｍの廃プラスチックを６０ｗｔ％混合した。なお、廃プラスチックの配合炭Ａおよび配合炭Ｂへの混合は、配合槽から石炭塔の間に設けられている混炭機を使用した。
【００３８】
（発明例１）
発明例１では、以下の方法で、配合炭Ａおよび配合炭Bを一度に炭化室へ装入した。なお、装炭車は既存の装炭車を用いた。
まず、装炭車により石炭塔の受入ホッパーから装炭車のチャージホッパーへ配合炭Ａを充填し、つづいて、配合炭Ａの上部へ配合炭Ｂを充填した。つぎに、装炭車を所定の窯へ移動させ、装炭車のチャージホッパー下部ゲートを開けて炭化室へ一度に装入した。この方法により、炭化室内には配合炭Ａの上に配合炭Bが装入された。
【００３９】
炭化室へ装入された配合炭Ａは２１．６ｔ、また、配合炭Ｂは１５．６ｔで合計装炭量は３７．２ｔ／窯であった。したがって、１窯当たりの廃プラスチック処理量は、配合炭Ａの混合量０．２２ｔおよび配合炭Ｂの混合量９．３６ｔの合計９．５８ｔであった。
【００４０】
また、乾留条件は、炉温（フリュー温度）が１０７０℃で火落ちまでの時間は１７時間、また、窯出しまでの置き時間は２時間であった。乾留終了後の押し出し機による窯出し、ＣＤＱによる冷却、破砕篩い分けによる整粒は通常の操業と全く同様に行った。その結果、得られた成品コークスの強度は通常の成品コークスの強度とほぼ同じく、ＤＩ30/15で９３．０であった。
【００４１】
また、ドライメン（コークスガス管）を点検した結果、廃プラスチックの熱分解残渣の炭化室外への搬送によるガス吸引系の付着および詰まりは認められず、さらに、副生品であるタールの粘度等から見て、熱分解残渣等の混入によるタール性状の悪化は認められなかった。
【００４２】
（発明例２）
発明例２では、以下の方法で、配合炭Bを配合炭Ａの１次収縮後に炭化室へ装入した。なお、装炭車は発明例１の場合と同様に既存の装炭車を使用した。
まず、装炭車にて配合炭Aを通常の装入量である３７．２ｔ装入し乾留を開始し、その後、３０分経過後に配合炭Ｂを装炭車にて０．７６ｔ装入した。なお、事前の測定によれば、３０分経過時点での配合炭Ａの１次収縮による装入レベルの低下は約２０ｃｍであり、この収縮量に対応する上部空間の増加容積は１．５５ｍ3である。この増加した容積に相当する配合炭Ｂ（嵩比重０．４９ｔ／ｍ3）の装入量が０．７６ｔである。
【００４３】
発明例２の場合、廃プラスチック処理量は、配合炭Ａの混合量０．３７ｔおよび配合炭Ｂの混合量０．４６ｔの合計０．８３ｔであった。発明例２の方法による廃プラスチックの処理量は発明例１の方法より少ないが、成品コークス量は、発明例２の方が多い。なお、得られたコークスの強度はＤＩ30/15で９３．０であった。
【００４４】
また、乾留温度、火落ちまでの時間、置き時間は発明例１の場合と同じである。乾留終了後の押し出し機による窯出し、ＣＤＱによる冷却、破砕篩い分けによる整粒も発明例１と全く同様に行った。その結果、得られた成品コークスの強度、また、廃プラスチック熱分解残渣の炭化室外への搬送によるガス吸引系の異常および熱分解残渣等の混入によるタール性状の悪化についても発明例１の場合と同様に認められなかった。
【００４５】
【発明の効果】
本願発明の方法によれば、成品コークスの強度低下を招くことなく、コークス炉により廃プラスチックを多量に処理でき、さらに、廃プラスチックの熱分解残渣が炭化室外へ搬送されてコークス炉ガスの吸引系を詰まらせたり、副成品であるタールへ混入して品質を低下させることがない。
【図面の簡単な説明】
【図１】本発明の実施例の条件を表１として示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a waste plastic treatment method in which waste plastic is charged into a coke oven together with blended coal and thermally decomposed, and further, the pyrolysis residue of waste plastic generated in the coke oven is a coke oven gas suction system. And a method for treating waste plastic by preventing carry-over into by-products.
[0002]
[Prior art]
Conventionally, waste plastics discharged as industrial waste and general waste have been treated mainly by incineration or landfill methods. However, in recent years, it has become necessary to review conventional processing methods in terms of environmental protection and resource recycling, and various new processing methods have been studied.
[0003]
One of them is a method using a coke oven. As this method, a method has been proposed in which waste plastic that has been crushed or granulated is mixed with blended coal, and the waste plastic is pyrolyzed in the process of dry distillation with the blended coal, and recovered as tar, light oil, and other gases.
[0004]
However, in the method of mixing waste plastic with blended coal in this way, it is known that the coke strength of the product is reduced when the particle size of the waste plastic is too large or the mixing ratio is high. Therefore, when high strength is required like coke for blast furnaces, it is necessary to pulverize the waste plastic to a particle size of about 1 mm, which increases the pulverization cost and the mixing ratio must be within 1 wt%. There is a drawback that waste plastics cannot be treated in large quantities.
[0005]
That is, in the method in which the waste plastic described above is mixed with coal blended and pyrolyzed in a coke oven, the restriction is that the waste plastic mixed with the coal affects the strength of the product coke.
[0006]
Therefore, as a treatment method having little influence on the strength of the product coke, there has been proposed a method of charging waste plastics into the upper portion of the charged coal blend without mixing it with the blended coal.
[0007]
For example, Japanese Patent Laid-Open No. 8-157834 discloses that a coke production charging coal is used alone, or waste plastic is blended in an amount of 0.1 wt% to 1.0 wt% and charged into a coke oven, and then a dedicated hopper is used. There has been proposed a method in which waste plastic is charged into the upper part of the charging coal via a carbonization chamber inlet and dry-distilled, and the waste plastic is thermally decomposed during the dry distillation and recovered as tar, light oil and gas. .
[0008]
According to this method, although the waste plastic mixed with the blended coal needs to be finely pulverized, since the mixing ratio is within 1 wt%, the influence on the strength of the product coke is small. In addition, the waste plastic charged at the top of the coke oven charging coal does not affect the strength of the product coke, so there is no need to finely pulverize, and the throughput can be increased compared to mixing with blended coal. There are advantages.
[0009]
In particular, the same Japanese Patent Application Laid-Open No. 8-157834 also proposes a method of continuously supplying waste plastic with a dedicated supply device that leads to the top space of the coke oven from the time of charging coal blending to the end of dry distillation. Has been. According to this method, the processing amount of waste plastic can be further increased.
[0010]
[Problems to be solved by the invention]
However, according to the study by the inventors, it was found that when waste plastic is pyrolyzed in a coke oven, it is rarely pyrolyzed and completely gasified, leaving a very light, finely divided pyrolysis residue. .
[0011]
For this reason, in the method proposed in Japanese Patent Laid-Open No. 8-157734, the waste plastic is charged into the upper part of the blended coal, so that this pyrolysis residue is conveyed by the coke oven gas generated during the dry distillation of the blended coal. When adhering to the furnace wall of the carbonization chamber or being transferred to the outside of the carbonization chamber, there is a problem that a situation occurs in which it adheres to the ascending pipe and the gas suction pipe and the gas suction line is blocked. Moreover, there is also a problem that the pyrolysis residue conveyed outside the carbonization chamber is mixed with tar, which is a by-product, to deteriorate the quality.
[0012]
[Means for Solving the Problems]
Therefore, the inventors repeatedly studied various methods for processing a large amount of waste plastic without affecting the strength of the product coke and preventing the pyrolysis residue of the waste plastic from being conveyed outside the carbonization chamber. As a result, the following invention was achieved.
[0013]
In the first aspect of the invention, first, a blended coal A that is D1 30/15 92 or more for coke production in which waste plastic is mixed in a range of 0 wt% to 1 wt% is charged into a coke carbonization chamber, and then While carbonizing coal A, carbonized coal B in which waste plastic was mixed at a ratio of 1 wt% to 60 wt% was placed at the top of the coal blend A, and the coal blend A and coal blend B were carbonized. In this method, coke is produced by co-decomposing the waste plastic and recovered as coke oven gas and by-product , and the waste plastic is treated together.
[0014]
In the second aspect of the invention, a blended coal A that is D1 30/15 92 or more for coke production in which waste plastic is mixed in a range of 0 wt% to 1 wt% is charged into a carbonization chamber, and then the blended coal After the primary shrinkage of A, the blended coal B in which waste plastic is mixed at a ratio of 1 wt% to 60 wt% is charged into the upper portion of the blended coal A, and the blended coal A and the blended coal B are dry-distilled into coke. In addition, a method for producing coke, characterized in that the waste plastic is pyrolyzed and recovered as coke oven gas and by-products, and processing the waste plastic together.
[0015]
As mentioned above, the combination coal A to be charged first and the combination coal B to be charged the second time are differentiated so that the coke produced from the combination coal A and the coke produced from the combination coal B can be easily separated. Considered.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The waste plastics targeted in the present invention are plastics as wastes that do not contain vinyl chloride. Moreover, when waste plastic contains vinyl chloride, it is waste plastic after dechlorination treatment. This is because vinyl chloride generates chlorine gas when it is decomposed and corrodes the gas suction equipment of the coke oven.
[0017]
In addition, if it is a hydrocarbon type, it can process not only plastics but rubbers, such as a waste tire. In order to investigate the decomposition behavior of such waste plastic in the coke oven, the inventors sealed one end of a steel pipe having an inner diameter of 5 cm and a length of 250 cm, filled it with waste plastic particles, and charged this steel pipe. It was inserted into the carbonization chamber vertically from the hole, and the state of carbonization of waste plastic was investigated.
[0018]
As a result, it was found that although the waste plastic in the steel pipe is thermally decomposed, it does not completely disappear due to gasification, and a black fine powder-like pyrolysis residue having a particle size of 1 mm or less remains. In addition, the weight of this thermal decomposition residue was about 20-30 wt% of the waste plastic particle weight filled initially. Moreover, the bulk specific gravity is about 0.2 and very light.
[0019]
The present invention has been made on the basis of the above knowledge, and is a blended coal for producing high-strength coke that can be charged into a blast furnace (hereinafter referred to as blended coal A), for example, DI 30/15 of coke. Is a blended coal having a target quality lower than that of blended coal A (hereinafter referred to as blended coal B), for example, a blend with a strength target DI 30/15 of 85.0 or less. Distinguish from charcoal. The blended coal A has a target grade corresponding to the required strength of the product coke, while the blended coal B is mixed with a large amount of waste plastic and charged into the upper portion of the blended coal A to thermally decompose the waste plastic. Prevents the generated pyrolysis residue from being transported out of the carbonization chamber.
[0020]
Usually, the bulk density of the coal blend is about 0.7 t / m 3, whereas the bulk density of the waste plastics 0.35 T / m 3 approximately, The bulk density of the thermal decomposition residue of waste plastic as described above in a 0.2t / m 3 approximately, bulk specific gravity of the waste plastic and thermal decomposition residue is less than the bulk density of the coal blend.
[0021]
Therefore, by mixing waste plastic having a small bulk specific gravity with blended coal B having a large bulk specific gravity, the waste plastic particles and the pyrolysis residue of the waste plastic are prevented from being conveyed to the outside of the carbonization chamber along with the coke oven gas. be able to.
[0022]
Moreover, since the target grade of the coal blend B is lowered, the coke produced by dry distillation of the coal blend B is a low-strength coke, so it is crushed and pulverized in the process of being conveyed from the coke oven to the blast furnace. Naturally, it is separated from high-strength coke produced from blended coal A. Coal blend strength goal of B is blended DI 30/15 than the strength goals coal A is 2 or more, more desirably preferable from the viewpoint of separating the coke is 5-7 degree lower obtained from both. The above is the outline of the present invention.
[0023]
Hereinafter, embodiments of the present invention will be specifically described.
First, the quality of blended coal A will be described. When producing blast furnace coke, the target coke strength target is, for example, DI 30/15 of 92 or more, for example, 93.0 is desirable as blast furnace coke. When the mixing ratio of waste plastic to blended coal increases by 1 wt%, the coke strength (DI 30/15 ) decreases by 0.5 to 1.0 points. The rate is preferably within 1 wt%, more preferably no waste plastic is mixed at all.
[0024]
Here, the coke strength (DI 30/15 ) is the strength of a rotating drum specified by JIS K 2151, and indicates the weight ratio of a sample having a particle diameter of 15 mm or more after the coke sample is rotated 30 times in the rotating drum. Is. In addition, the particle size of the waste plastic mixed with the blended coal A is preferably finely pulverized to the particle size of the blended coal (-3 mm is about 80 wt%). However, since the pulverization of the waste plastic is technically difficult, May be about 1 to 3 mm.
[0025]
The coke produced by dry distillation of the blended coal B is mixed with a large amount of waste plastic, and therefore the strength is lowered. Therefore, the quality of the blended coal B is not necessarily the same as that of the blended coal A. Rather, it is easier to separate the high-strength coke produced from blended coal A and the low-strength coke produced from blended coal B when the quality of blended coal B is significantly lowered relative to the quality of blended coal A. The risk of low strength coke being charged into the blast furnace is reduced.
[0026]
For example, if the strength target for blended coal A is set to DI 3.0 / 15 at 93.0, while the strength target for blended coal B is set to DI 30/15 at 84.0, it was produced from blended coal B. The low-strength coke is pulverized in the kiln unloading process, the cooling process by CDQ, and the conveying process in the middle, so that it is almost separated under the sieving process.
[0027]
However, when the ratio of blended coal B is increased with respect to blended coal A as will be described later, if the strength of the coke produced from blended coal B is too low, it will not be possible to start out the kiln, The charging rate of blended coal B is preferably about 1/3 to 1/2 of the total amount of charcoal, and the target strength of blended coal B should be at least DI 30/15 of 80 or more.
[0028]
The proportion of waste plastic mixed with blended coal B should be at least the proportion blended with blended coal A from the viewpoint of waste plastic treatment, that is, 1 wt% or more. If the mixing ratio is too large, the effect of preventing the pyrolysis residue from being transported by the blended coal B is weakened. Therefore, the ratio of the waste plastic is preferably within 60 wt%.
[0029]
The waste plastic mixed with blended coal B does not need to be finely pulverized like the waste plastic mixed with blended coal A, and can be determined by taking into account the size of each hopper outlet and carbonization chamber inlet. It ’s fine.
[0030]
Moreover, when increasing the processing amount of waste plastics, it is sufficient to reduce the blended coal A from the normal charged amount and to charge a larger amount of blended coal B accordingly. However, when the ratio of blended coal B is set to 1/3 or more of the total blended coal in the coking chamber, the target strength of blended coal B will not be set to 80 or more with DI 30/15 , and it will be clogged when leaving the kiln. It becomes difficult to extrude.
[0031]
Next, a method for charging the blended coal B will be described.
An existing charcoal vehicle can be used for charging the blended coal B. If the blended coal A is to be reduced, the charging timing of the blended coal B may be any time from immediately after the blended coal A is charged until the end of dry distillation. However, it is necessary to set the charging timing of the blended coal B so that the blended coal B finishes the carbonization by the end of the dry distillation of the blended coal A.
[0032]
In addition, blended coal A and blended coal B can be charged at a time with existing coal-equipped vehicles. In this case, a predetermined amount of blended coal A is first charged from each coal hopper of the coal tower to the charge hopper of the coal-equipped vehicle, and then blended coal B is filled thereon, and when it is extracted from the lower end of the charge hopper, carbonization is performed. The chamber can be charged with blended coal A and blended coal B at the top.
[0033]
In addition, when blended coal A cannot be reduced, blended coal A undergoes primary shrinkage during the dry distillation process, and the upper space expands. Therefore, if blended coal B is charged after primary shrinkage of blended coal A, charging is performed. can do.
[0034]
In general, coal undergoes primary and secondary shrinkage resulting in a volume shrinkage of about 6% during the carbonization process. The primary shrinkage occurs until 30 to 60 minutes have elapsed after charging the blended coal, and the secondary shrinkage occurs between the primary shrinkage and the end of dry distillation. However, if the blended coal B is charged after the secondary shrinkage, the dry distillation of the blended coal B does not end within the specified time. Therefore, the charging timing of the blended coal B is preferably after the primary contraction. Therefore, if the blended coal A is not reduced, the blended coal B can be charged after the blended coal A undergoes primary contraction and the upper space of the blended coal A is expanded.
[0035]
Coke produced from blended coal A and blended coal B is transferred to the blast furnace after leaving the kiln by an extruder, extinguishing with CDQ, and sizing after completion of dry distillation, but the coke produced from blended coal B has strength. Since it is set low, it is pulverized and finely divided in the middle of conveyance and separated as small coke under the sieve, so there is little concern that low strength coke produced from blended coal B will be charged into the blast furnace. The small coke recovered as the sieve is used for applications other than blast furnace coke, for example, powder coke for sintering.
[0036]
【Example】
Hereinafter, as examples of the present invention, when blended coal B is charged at once with blended coal A and a loaded car (Invention Example 1) and when charged after primary contraction of blended coal A (Invention Example 2). Will be described. Commercial chamber furnace coke oven dimensions used in Invention Example 1 and Invention Example 2, quality of blended coal A and blended coal B (strength target values), and properties and mixing ratios of waste plastic mixed in each blended coal, respectively. It shows in Table 1 of FIG.
[0037]
In both Invention Example 1 and Invention Example 2, the waste plastic is obtained by removing vinyl chloride plastic that generates chlorine gas that causes corrosion of the gas suction system, and the particle size range was crushed to a range of approximately 1 mm to 10 mm. A sample having a mesh size of 3 mm and a particle size of -3 mm was used separately. The blended coal A was mixed with 1 wt% of -3 mm waste plastic, and the blended coal B was mixed with 60 wt% of +3 mm waste plastic. In addition, the blending machine of the waste plastic to the blended coal A and the blended coal B used the coal blender provided between the blending tank and the coal tower.
[0038]
(Invention Example 1)
In Invention Example 1, blended coal A and blended coal B were charged into the carbonization chamber at once by the following method. In addition, the existing charcoal vehicle was used as the charcoal vehicle.
First, blended coal A was charged from the receiving hopper of the coal tower to the charge hopper of the coal-equipped vehicle by means of a coal loading vehicle, and then the blended coal B was charged above the blended coal A. Next, the charcoal vehicle was moved to a predetermined kiln, the charge hopper lower gate of the charcoal vehicle was opened, and the charcoal chamber was charged at once. By this method, blended coal B was charged onto blended coal A in the carbonization chamber.
[0039]
The blended coal A charged into the carbonization chamber was 21.6 t, the blended coal B was 15.6 t, and the total coal charge was 37.2 t / kiln. Accordingly, the amount of waste plastic treated per kiln was a total of 9.58 t including the blending amount 0.22 t of blended coal A and the blending amount 9.36 t of blended coal B.
[0040]
Moreover, the dry distillation conditions were a furnace temperature (Flue temperature) of 1070 ° C., a time until the fire broke down for 17 hours, and a settling time until the kiln was removed was 2 hours. After completion of dry distillation, the kiln was discharged by an extruder, cooled by CDQ, and sized by sieving and sieving. As a result, the strength of the obtained product coke was 93.0 in DI 30/15 , almost the same as the strength of ordinary product coke.
[0041]
In addition, as a result of inspecting dry men (coke gas pipe), there was no adhesion or clogging of the gas suction system due to the transfer of waste plastic pyrolysis residue outside the carbonization chamber. As a result, no deterioration of the tar properties due to the mixture of pyrolysis residue or the like was observed.
[0042]
(Invention Example 2)
In Invention Example 2, blended coal B was charged into the carbonization chamber after the primary contraction of blended coal A by the following method. In addition, the charcoal vehicle used the existing charcoal vehicle similarly to the case of the example 1 of an invention.
First, blending coal A was charged with 37.2 t, which is a normal charging amount, and dry distillation was started with a charcoal vehicle, and then blended coal B was charged with 0.76 t with a charcoal vehicle after 30 minutes. In addition, according to the prior measurement, the decrease in the charging level due to the primary shrinkage of the blended coal A after 30 minutes is about 20 cm, and the increased volume of the upper space corresponding to this shrinkage is 1.55 m 3. It is. The charging amount of blended coal B (bulk specific gravity 0.49 t / m 3 ) corresponding to the increased volume is 0.76 t.
[0043]
In the case of Invention Example 2, the amount of waste plastic treated was 0.83 t in total, which was 0.37 t of blended coal A and 0.46 t of blended coal B. The amount of waste plastic processed by the method of Invention Example 2 is smaller than that of Invention Example 1, but the amount of product coke is larger in Invention Example 2. The strength of the obtained coke was 93.0 as DI 30/15 .
[0044]
Further, the carbonization temperature, the time until the fire falls, and the setting time are the same as in the case of Invention Example 1. After the dry distillation, the kiln was discharged by an extruder, cooled by CDQ, and sized by sieving and sieving. As a result, the strength of the obtained product coke, the abnormality of the gas suction system due to the conveyance of the waste plastic pyrolysis residue outside the carbonization chamber, and the deterioration of the tar properties due to the mixture of the pyrolysis residue and the like are also the case of Invention Example 1. Similarly, it was not recognized.
[0045]
【The invention's effect】
According to the method of the present invention, it is possible to treat a large amount of waste plastic by a coke oven without causing a reduction in strength of the product coke, and further, a pyrolysis residue of the waste plastic is conveyed out of the carbonization chamber, and a coke oven gas suction system It does not clog or mix with tar, which is a by-product, to reduce the quality.
[Brief description of the drawings]
FIG. 1 is a diagram showing the conditions of an embodiment of the present invention as Table 1. FIG.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP27635799A JP4061785B2 (en) | 1999-09-29 | 1999-09-29 | Waste plastic treatment method in coke oven |
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|---|---|---|---|
| JP27635799A JP4061785B2 (en) | 1999-09-29 | 1999-09-29 | Waste plastic treatment method in coke oven |
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| JP4061785B2 true JP4061785B2 (en) | 2008-03-19 |
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| WO2020205396A1 (en) * | 2019-03-29 | 2020-10-08 | Eastman Chemical Company | Campaigning gasification of textiles and plastics and solid fossil fuels to produce organic compounds |
| WO2020205405A1 (en) * | 2019-03-29 | 2020-10-08 | Eastman Chemical Company | Campaigning gasification of textiles and plastics and solid fossil fuels |
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