JP4017360B2

JP4017360B2 - Method for producing activated carbon

Info

Publication number: JP4017360B2
Application number: JP2001162881A
Authority: JP
Inventors: 晴久上田; 久朗神山; 公児齋藤; 征亜木下; 義則中馬; 紀道高橋
Original assignee: Navitas Co Ltd; Nippon Steel Corp
Current assignee: Navitas Co Ltd; Nippon Steel Corp
Priority date: 2001-05-30
Filing date: 2001-05-30
Publication date: 2007-12-05
Anticipated expiration: 2021-05-30
Also published as: JP2002348111A

Description

【０００１】
【発明の属する技術分野】
本発明は、乾式脱硫脱硝プロセスにおいて吸着剤として使用される高強度、高吸着能を有する活性炭の製造方法に関するものである。
【０００２】
【従来の技術】
活性炭吸着剤の欠点を解消するため種々の研究が行われ、石炭を原料としこれに各種の結合剤を加えて成形し、特定の条件下で乾留、賦活することによって脱硫脱硝に適した成形活性炭が提案されている。例えば、特公昭62−51885 号公報には、石炭から活性度の高い半成コークスを製造しこれを主原料としこれに数種の石炭と結合剤を加えてロガ指数が20〜30％になるように強度調整後乾留、賦活する方法が開示されている。また、特開平11−157822公報にはボタン指数を1.5 〜4 に原料石炭の配合を調整後乾留、賦活する方法が開示されている。しかし、これらのロガ指数やボタン指数は耐摩耗性等の強度を表す指数、配合炭の粘結性を表す指数であって、特定範囲のロガ指数、ボタン指数に石炭の配合を調整することで耐摩耗性や強度に優れた活性炭を製造することはできるが、必ずしも脱硫性能又は脱硫脱硝性能の向上を図ることはできない。
【０００３】
また、特開平11−349317公報には揮発分と流動度が最適範囲にある石炭を配合することで強度、吸着能に優れた活性炭を製造する方法が開示されている。しかしながら、この方法においては用いる主原料、副原料や加熱温度、加熱速度などの製造条件に種々の制約があり、成分変動の少ない主原料や副原料の入手が困難であるとともに、製造工程が複雑化して簡単に活性炭を製造することができずコストアップを招くという問題がある。
【０００４】
【発明が解決しようとする課題】
本発明は上記した従来の問題点を解決し、高強度で、高吸着能（例えばＳＯ_x吸着能）を有し脱硫性能に優れ、且つ、移動層方式の乾式脱硫脱硝プロセスでの循環使用に耐えるだけの高い強度を有する活性炭の製造方法を提供するためになされたものである。
【０００５】
【課題を解決するため手段】
発明者らは、鋭意検討を重ねた結果、石炭を原料とする脱硫用活性炭又は脱硫脱硝用活性炭の製造方法において、該石炭の軟化溶融温度域でのＮＭＲ（核磁気共鳴）測定結果から石炭粒子内に存在する横緩和時間が長い成分、即ち、易動性水素成分の量（溶融指数) が特定範囲にある石炭を選定、配合することで、極めて高い脱硫性能（例えばＳＯ_x吸着能）を有し、しかも移動層での長時間使用に耐え得る高強度で堅牢な活性炭の製造方法を発明するに至った。
【０００６】
上記した課題を解決するためになされた本発明は、石炭に300 〜600 ℃の温度で低温乾留を施した半成コークスを主原料とし、粘結性を有する石炭を副原料とし、これらを結合剤とともに混合成形した成形物に炭化、賦活の熱処理を行なって活性炭とする活性炭の製造方法において、主原料である半成コークスの原料炭として、軟化溶融状態にある温度でのＮＭＲ測定結果から算出した易動性水素成分の量が30％以下である石炭を用いることを特徴とする活性炭製造方法を請求項１に係る発明とする。また、前記した発明において副原料として用いる粘結性を有する石炭として、軟化溶融状態にある温度でのＮＭＲ測定結果から算出した易動性水素成分の量が35〜45％である石炭を用いる活性炭製造方法を請求項２に係る発明とする。
【０００７】
【作用】
本発明の活性炭の製造方法は、主原料である半成コクースの原料炭として、軟化溶融温度でのＮＭＲ測定結果から算出した易動性水素成分量が30％以下のものを用いることにより、ＳＯ_x分子を吸着するのに適した直径10Å付近のミクロ孔を多数形成することができるので、これから製造した活性炭は高強度でＳＯ_x吸着能に優れたものとなる。また、主原料である前記したような半成コクースに混合する副原料である成形物の原料炭として、ＮＭＲ測定結果から算出した易動性水素成分量が35〜45％である粘結性石炭を用いることによって、さらに外観が良好で高いロガ強度と良好なＳＯ_x吸着能を有する活性炭を製造することができる。
【０００８】
【発明の実施の形態】
本発明の実施の形態を図１に示す実施例の工程図と併せ説明する。
次いで、本発明を実施例により更に具体的に説明するが、本発明は実施例により何ら制限されるものではない。なお、易動性水素成分の量、ロガ強度、脱硫脱硝率、硫安生成による粉化率は下記の測定により求めた。
【０００９】
〈易動性水素成分の量〉
対象とする石炭試料を核磁気共鳴装置専用の試料管に装入する。なお、石炭試料は試料管に入るサイズである数ミリメートル以下であれば、特にその大きさや形状に制限はない。測定の手法としては、水素90度のパルス幅は8 μsec 、エコー時間は50μsec 〜3msec 、繰り返し時間は5msec 〜1sec、積算回数は512 回とする。データのサイズはＸ方向で512 ポイント、Ｙ方向で512 ポイント、Ｚ方向は1 〜512 ポイントに設定する。その際に試料を3 ℃／min で昇温させながら、Ｘ、Ｙ、Ｚの3 軸にそれぞれ、89gauss ／cm、96gauss ／cm、107gauss／cmの磁場勾配を短時間で与える方法で測定を行い、石炭の水素核ＮＭＲイメージング画像を得る。更に昇温させながら、同じ測定をすることで、石炭が軟化溶融状態のＮＭＲイメージ画像を得る。得られた画像から、適当な横緩和時間での分布と易動性水素成分の存在量を算出する。ここで易動性水素成分の存在量は、軟化溶融温度域で、横緩和時間が100 μsec 以上である成分の量を意味する。ここで多重パルスや横緩和時間に関しては、特開平11−326248号中にその内容を記載している。
【００１０】
〈ロガ強度〉
活性炭の装入、排出が可能で、円筒の対角に２箇所高さ30mmの邪魔板を設置した、回転円筒 (φ200 ×70) 内に活性炭サンプルを30g 装入、60rpm の回転速度で円筒を1000回転させた。その後活性炭を取り出し、3mm メッシュの篩にて微粉分を除去し、投入活性炭重量に対する3mm 篩上の重量割合を求め、下記(1) 式によりロガ強度を決定した。なお、ロガ強度試験機を図7 に示した。
【数１】

【００１１】
〈ＳＯ_x吸着能〉
粒径を1 〜3mm に調整した活性炭試料10ccに合成ガス(SO₂ 2vol%、O₂ 5vol%、N₂ 83vol% 、H₂O 10vol%) を3Nリットル/minの流量にて100 ℃で3 時間接触させSO₂ガスを吸着させる。その後、400 ℃で1.5 時間N₂気流下で加熱し、この間N₂に同伴され排出される、前操作にて吸着したSO₂ガスを全量H₂O₂ 3% 水溶液に吸収させる。(SO₂+H₂O₂ →H₂SO₄、硫酸として回収) 吸収液をJIS K-0103に記載されるアルセナゾIII法による中和滴定により決定されるSO₂ 吸着量をSO_x吸着能とした。活性炭１ｇあたりのSO₂ 吸着量をmg/g-ac の単位で表す。尚、ac:activated carbon(活性炭) である。
【００１２】
〈脱硝率〉
直径φ50の円筒カラム (脱硝試験反応容器) 内に170cc の活性炭を充填し90℃に加熱する。合成ガス(SO₂ 135ppm 、NO 160ppm 、NH₃450ppm、O₂ 10%、H₂O 10% 、残りN₂) を90℃に加熱し、2Nリットル/minの流量にて活性炭充填層に接触させる。合成ガスを20時間通気した後の活性炭充填層入側と出側のNO濃度を測定し、下記(2) 式にて脱硝率を決定した。
【数２】

【００１３】
〈硫安生成による粉化率〉
直径φ50の円筒カラム (脱硝試験反応容器) 内に170cc の活性炭を充填し90℃に加熱する。合成ガス(SO₂ 135ppm 、NO 160ppm 、NH₃450ppm、O₂ 10%、H₂O 10% 、残りN₂) を2Nリットル/minの流量にて活性炭充填層に接触させる。合成ガスを100 時間通気した後、円筒カラムより活性炭全量を抜き出し、ビーカー中で水に含浸させ軽く攪拌する。次いで、1mm 金網で濾過し、濾液( 活性炭微粉を含む) と活性炭ペレットに分ける。濾液から活性炭微粉をさらに濾過抽出し、乾燥した後重量を測定し、活性炭微粉重量とする。活性炭ペレットは400 ℃で1.5 時間N₂気流下で加熱し再生処理を行った後、重量を測定し、再生後の活性炭ペレット全重量とする。前記の活性炭微粉重量と再生後の活性炭ペレット重量を合計して再生後の活性炭全重量とする。再生した活性炭ペレットは3mm の篩にかけ、篩下重量と活性炭微粉重量を合計し-3mm重量を測定し、(3) 式にて求めた量を硫安生成による粉化率とした。なお、図８に脱硝率、硫安生成による粉化率の測定装置を示した。
【数３】

【００１４】
さて、図１において、１は低温乾留を施すことにより主原料半成コークスの原料炭とする石炭であるが、この石炭はその軟化溶融温度域に相当する温度でのＮＭＲ測定結果から算出した易動性水素成分量が30％以下、好ましくは15％以上30％以下の範囲のものである。軟化溶融温度域に相当する温度でのＮＭＲ測定結果から算出した易動性水素成分量を前記した範囲とするのは、易動性水素成分量が30％を超えるとＳＯ_x分子の吸着に効果を発揮する直径10Å付近のミクロ孔容積が低下し、一方、１５％未満としてもＳＯ_x吸着能の向上効果は飽和し大きな向上は望めないからである。
【００１５】
この石炭１は低温乾留炉２に装入して６％以下の酸素濃度で、300 ℃以上600 ℃以下、好ましくは400 ℃以上550 ℃以下の加熱雰囲気中で、炉内加熱部での滞留時間が15分以上120 分以下、好ましくは25分以上80分以下の条件にて低温乾留することにより半成コークスとする。低温乾留条件を前記のようにしたのは、加熱雰囲気の温度が300 ℃以下、あるいは炉内での滞留時間が15分以下では半成コークスとして坦持すべき細孔構造を形成するために十分な揮発分の消失が進行せず、このため、単に結晶水と若干の揮発分のみが揮発しただけの細孔構造に乏しい半成コークスとなり、このような加熱が不十分の半成コークスを主原料として活性炭を製造しようとしても、賦活工程で蒸気等の賦活ガスとの賦活反応が十分に進行せず、ＳＯ_xの吸着能力が乏しい活性炭しか得られず、−方、加熱雰囲気の温度が600 ℃以上、あるいは炉内での滞留時間が120 分以上になると、細孔構造形成に十分な揮発分の消失は進行するが、半成コークス自体の基質の黒鉛化が過度に進行する。黒鉛結晶は構成する炭素原子が規則的に配列した安定な組織であるため、活性炭中に多く存在するとＳＯ_xの吸着能のみならず、脱硝のための触媒活性が著しく低下してしまう。
【００１６】
主原料となる半成コークスは、その微細気孔と、多少残存する粘結性によって製品となる活性炭のＳＯ_xの吸着能や強度を決定付けるため、半成コークスを製造するための原料となる石炭の選定が大きな問題となる。活性炭として高いＳＯ_x吸着能を坦持させるには、主原料として用いる半成コークスの状態でＳＯ_x分子を吸着するために適した気孔径の細孔が多数形成されていることが望ましい。表１に石炭化度の異なる１６種類の石炭について、軟化溶融温度域に相当する温度でのＮＭＲ測定結果から算出した易動性水素成分の量を示す。なお、対象とした石炭の軟化溶融温度は350 ℃から510 ℃の範囲であった。
【００１７】
また、副原料として配合する粘結性石炭のＮＭＲ測定結果から算出した易動性水素成分量は35〜45％とするのが望ましい。その理由は易動性水素成分量が35％未満の石炭を副原料として用いた場合には、得られる活性炭の外観は良好であるが、ロガ強度が大幅に低下するからであり、一方、易動性水素成分量が45％を超える石炭を副原料として用いた場合には、得られる活性炭が粘結性過多により膨れて亀裂が発生するとともに、内部に孔径の大きい気孔が多数形成されてロガ強度が低下してしまうからである。
【００１８】
【表１】

【００１９】
図２に上記１６種の石炭を450 ℃で60分間加熱し製造した半成コークスの細孔径分布の測定結果一例を示す。製造した半成コークスの細孔径分布を測定した結果、上記石炭は細孔径が10Å付近の細孔容積の発達度合いからＡ、Ｂ、Ｃ、Ｄの４つに分類することが可能である。すなわち、易動性水素成分の量が30％以下となるＡ分類に属する石炭から製造した半成コークスでは、易動性水素成分の量が30％を超えるＢ、Ｃ、Ｄ分類に属する石炭から製造する半成コークスに対し、同一加熱条件でも特異的に直径10Å付近のミクロ孔容積が発達した構造を持つ。また、Ｂ、Ｃ、Ｄ分類に属する石炭から製造した半成コークスでは易動性水素成分の量が増加するに従い、直径10Å付近のミクロ孔容積が低下する。Ｂ分類に属するものでは外観上膨れや膨張は見られないが、Ｃ分類およぴＤ分類のものでは著しく膨れが生じ、該半成コークスの破断面は粗大な気孔とともに、半成コークスの外観も膨れや膨張による粗大な気孔が多く発生する。特に、Ｄ領域のものでは石炭の原形を止めないほど石炭粒子が膨れ、粒子同士も烈しい溶着が生じるため、活性炭を製造するための操業上問題となる。
【００２０】
次に、図３に450 ℃で低温乾留を行った際の、加熱時間と製造した半成コークスのＳＯ_x吸着能の測定結果を示す。この結果によれば、Ａ分類に属する石炭から製造した半成コークスが最もＳＯ_xの吸着能に優れ、石炭中の易動性水素成分の量が増加するに従いＳＯ_xの吸着能は低下する。すなわち、主原料として用いる半成コークスの状態でＳＯ_xの吸着能を有効に高めるためには、直径10Å付近のミクロ孔容積をできる限り増加させる必要があり、このためには軟化溶融温度領域でのＮＭＲ測定結果から求める易動性水素成分の量が30％以下となるＡ領域に属する石炭に低温乾留を行った半成コークスを主原料とすることが望ましい。
【００２１】
この半成コークスは主原料として粉砕機３に投入して粉砕する。また、副原料として用いる粘結性石炭４も粉砕機３に投入して粉砕する。次いで、粉砕した主原料の半成コークスと副原料の粘結性石炭４とを 9：1 から 5：5 の割合、好ましくは 8：2 から 6：4 の割合で混合して混合粉砕物粒とする。この混合粉砕物粒は混練機７に移されるが、その際、結合剤５としてタール、ピッチ等の石炭系あるいは石油系重質油、パルプ製造廃液等の他、成形助剤６を加えて混練する。この混練したものを成形機８に導入して径5 〜20φ、長さ5 〜30mmの多数の成形物粒に成形し、次いで、各成形物粒は炭化賦活炉９、例えばロータリーキルン等に定量的に装入し、蒸気１０、窒素ガス１１を賦活が有効に進行するよう添加しつつ、750 〜900 ℃の温度で炭化、賦活することによって製品12、即ち高強度、高脱硫脱硝能を有する活性炭を製造することができる．
【００２２】
図４に主原料とともに混合する副原料石炭の添加量とロガ強度の関係について示す。ここで主原料の半成コークスはＡ領域に属する銘柄の石炭１を450 ℃で60分間加熱したものを用いている。副原料として配合する粘結性石炭がＡおよぴＢ領域に属するものを使用した活性炭では、外観上、膨れや膨張による亀裂の発生は見られず製品形状は良好であり、分布の狭い粒度構成であるが、ロガ強度が既製活性炭より大幅に低い値となる。また、副原料として配合する粘結性石炭がＤ領域に属するものを使用した活性炭では粘結性過多による膨れが発生し、内部破断面も孔径の大きい気孔が多数形成され、ロガ強度も既製活性炭よりも低い値となる。−方、副原料として配合する粘結性石炭がＣ領域に属するものを使用した活性炭では、主原料の半成コークスと副原料の粘結性石炭の配合割合が 9:1ないし 5：5 の範囲において、膨れや膨張による亀裂の発生が無く製品形状が良好で分布の狭い粒度構成で、かつロガ強度が既製活性炭よりも高い活性炭が得られる。すなわち、堅牢な活性炭を得ようとする場合、軟化溶融温度域に相当する温度でのＮＭＲ測定結果から算出した易動性水素成分量が35％以上45％以下の範囲にある粘結性石炭を副原料として選定することが重要である。
【００２３】
【実施例】
上記方法により製造した活性炭の比表面積とＳＯ_x吸着能の関係を比較例と併せて図５に示す。表１に示した易動性水素成分の量が異なる石炭16種のうち、易動性水素成分の量が30％以下であるＡ領域に属する石炭６種に低温乾留を行い得られる半成コークスを主原料として活性炭を製造した。Ａ領域に属する石炭を粒径50mm以下に粗粉砕し、外熱式ロータリーキルンに導き、酸素濃度が２％以下、加熱雰囲気温度が450 ℃で炉内の滞留時間が60分になるよう乾留して半成コークスとし、その後この半成コークスを粉砕機３にて粉砕して主原料とした。また、このとき表１に示す易動性水素成分の異なる石炭16種のうち、易動性水素成分の溶融指数が40．2 ％の瀝青炭系石炭を粉砕機３にて粉砕して副原料とした。これらの主原料と副原料とを質量比で 8：2 になるよう配合したものに、結合剤５として石炭系軟ピッチを20質量％、成形助剤６として水を15質量％添加し、混練機７にて十分混練したものを押し出し成形機８により直径10φ、長さ10mmの円柱状に成形した。この成形物を外熱式口一タリーキルンに導き、酸素濃度1 ％、賦活蒸気吹き込み量が成形物1kg 当たり1.Okg の雰囲気下で、成形物の最高到達温度830 ℃、平均の昇温速度が18℃／min 、800 ℃以上での保持時間が40min となるよう加熱し、炭化、賦活することによって活性炭を製造した．このようにして得られた活性炭は、ロガ強度97.9 〜98.8％、ＳＯ_x吸着能72.0〜80.2mg/g-ac 、脱硝率48％、硫安生成による粉化率0.01％と脱硫脱硝用活性炭として非常に優れていた。
【００２４】
［比較例１］
表１に示した易動性水素成分の量が異なる石炭16種のうち、易動性水素成分の量が30％を超え35％未満であるＢ領域に属する石炭２種に低温乾留を行い得られた半成コークスを主原料として活性炭を製造した。Ｂ領域に属する石炭を粒径50mm以下に粗粉砕し、外熱式ロータリーキルンに導き、酸素濃度義度が2 ％以下、加熱雰囲気温度が450 ℃で炉内の滞留時間が60分になるよう乾留して半成コークスとし、その後この半成コークスを粉砕機３にて粉砕して主原料とした。また、このとき表１に示す易動性水素成分の異なる石炭16種のうち、易動性水素成分の溶融指数が40．2 ％の瀝青炭系石炭を粉砕機にて粉砕して副原料とした。これらの主原料と副原料とを質量比で8 ：2 になるよう配合した配合炭に、結合剤５として石炭系軟ピッチを配合炭に対して20質量％、成形助剤６として水を15質量％添加し、混練機７にて十分混練したものを押し出し成形機８により直径10φ、長さ10mmの円柱状に成形した。この成形物を外熱式ロータリーキルンに導き、酸素濃度1 ％、賦活蒸気吹き込み量が成形物1kg 当たり1.0kg の雰囲気下で、成形物の最高到達温度830 ℃、平均の昇温速度が 18 ℃/min、800 ℃以上での保持時間が40min となるよう加熱し、炭化、賦活することによって活性炭を製造した。このようにして得られた活性炭は、ロガ強度が97.1〜98.2％と十分であったが、ＳＯ_x吸着能が45.5〜47.Omg/g-ac 、脱硝率38％、硫安生成による粉化率0.9 ％と実施例に比べ著しく劣るものであった。
【００２５】
［比較例２］
表１に示した易動性水素成分の量が異なる石炭16種のうち、易動性水素成分の量が35％以上45％以下であるＣ領域に属する石炭６種に低温乾留を行い得られた半成コークスを主原料として活性炭を製造した。Ｃ領域に属する石炭を粒径50mm以下に粗粉砕し、外熱式口一タリーキルンに導き、酸素濃度が2 ％以下、加熱雰囲気温度が450 ℃で炉内の滞留時間が60分になるよう乾留して半成コークスとし、その後この半成コークスを粉砕機にて粉砕して主原料とした。また、このとき表１に示す易動性水素成分の異なる石炭16種のうち、易動性水素成分の溶融指数が40．2 ％の瀝青炭系石炭を粉砕機にて粉砕して副原料とした。これらの主原料と副原料を重量比で8 ：2 になるよう配合した配合炭に、結合剤５として石炭系軟ピッチを配合炭に対して20質量％、成形助剤６として水を配合炭に対して15質量％添加し、混練機７にて十分混練したものを押し出し成形機８により直径10φ、長さ10mmの円杜状に成形した。この成形物を外熱式ロータリーキルンに導き、酸素濃度1 ％、賦活蒸気吹き込み量が成形物1kg 当たり 1.0kgの雰囲気下で、成形物の最高到達温度830 ℃、平均の昇温速度が18℃／min 、800 ℃以上での保持時間が40min となるよう加熱し、炭化、賦活することによって活性炭を製造した。このようにして得られた活性炭は、ロガ強度が92.0〜94.8％、ＳＯ_x吸着能が33.0〜36.Omg/g-ac 、脱硝率38％、硫安生成による粉化率1.2 ％であり、何れの性能も実施例に対して著しく劣るものであった。
【００２６】
［比較例３］
表１に示した易動性水素成分の量が異なる石炭16種のうち、易動性水素成分の量が45％を超えるＤ領域に属する石炭３種に低温乾留を行い得られる半成コークスを主原料として活性炭を製造した。Ｄ領域に属する石炭を粒径50mm以下に粗粉砕し、外熱式ロータリーキルンに導き、酸素濃度が2 ％以下、加熱雰囲気温度が450 ℃で炉内の滞留時間が60分になるよう乾留して半成コークスとした後、該半成コークスを粉砕機にて粉砕して主原料とした。また、このとき表１に示す易動性水素成分の異なる石炭16種のうち、易動性水素成分の溶融指数が40．2 ％の瀝青炭系石炭を粉砕機３にて粉砕して副原料とした。これらの主原料と副原料を重量比で8 ：2 になるよう配合した配合炭に、結合剤５として石炭系軟ピッチを配合炭に対して20質量％、成形助剤６として水を15質量％添加し、混練機７にて十分混練したものを押し出し成形機８により直径10φ、長さ10mmの円柱状に成形した。この成形物を外熱式口一タリーキルンに導き、酸素濃度1 ％、賦活蒸気吹き込み量が成形物1kg 当たり1.0kg の雰囲気下で、成形物の最高到達温度830 ℃、平均の昇温速度が18℃/min、800 ℃以上での保持時間が40min となるよう加熱し、炭化、賦活することによって活性炭を製造した。このようにして得られた活性炭は、ロガ強度が90.2〜92.1％、ＳＯ_x吸着能が10.8〜12.0mg/g-ac 、脱硝率5 ％、硫安生成による粉化率1.0 ％であり、何れの性能も実施例に比べて著しく劣るものであった。
【００２７】
なお、図５にはミクロ孔形成による比表面積の増大によるＳＯ_xの吸着能の向上を示すが、大きな比表面積を有するＡ領域の石炭により製造された活性炭が高い脱硫性能を有することが分かる。このような比表面積は、図６に示すように、低温乾留での加熱雰囲気温度によって大きく変動するので、乾留温度を適切に設定することが望まれる。
【００２８】
【発明の効果】
以上に説明したように、本発明の活性炭の製造方法は、低温乾留を施して主原料の半成コークスとする石炭として、軟化溶融温度でのＮＭＲ測定結果から算出した易動性水素成分量が30％以下のものを用いることにより、ＳＯ_x分子を吸着するために適した直径10Å付近のミクロ孔を多数形成することができて、これから製造した活性炭を高強度で脱硫性能（例えばＳＯ_x吸着能）に優れたものとすることができる。また、主原料である半成コークスと混合する副原料として、ＮＭＲ測定結果から算出した易動性水素成分量が35〜45％である粘結性石炭を用いることによって、さらに外観が良好で高いロガ強度と良好な脱硫（ＳＯ_x吸着能) 性能及び低い硫安生成による粉化率を有する活性炭を製造することができる。更に脱硫脱硝用活性炭として優れたものが得られる。
【図面の簡単な説明】
【図１】活性炭を製造する工程のフロー図である。
【図２】易動性水素成分の量によって分類された４種の石炭のミクロ孔の体積分布を示す説明図である。
【図３】低温乾留時間と半成コークスのＳＯ_xの吸着能との関係図である。
【図４】副原料である粘結性を有する石炭の種類、配合割合とロガ強度との関係図である。
【図５】主原料となる半成コークスの原料石炭の種類と比表面積の増大によるＳＯ_xの吸着能の向上を示す関係図である。
【図６】低温乾留の温度による活性炭の比表面積変化を示す関係図である。
【図７】ロガ強度試験機の説明図である。
【図８】脱硝率、硫安生成による粉化率の測定方法を示す説明図である。
【符号の説明】
１半成コークスとする石炭
２低温乾留炉
３粉砕機
４粘結性石炭
５結合剤
６成形助剤
７混練機
８成形機
９炭化、賦活炉
１０蒸気
１１窒素ガス
１２製品[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing activated carbon having high strength and high adsorption capacity used as an adsorbent in a dry desulfurization denitration process.
[0002]
[Prior art]
Various studies have been conducted to eliminate the disadvantages of activated carbon adsorbents. Molded activated carbon is suitable for desulfurization and denitration by using coal as a raw material, molding it with various binders, dry distillation and activating under specific conditions. Has been proposed. For example, in Japanese Patent Publication No. 62-51885, semi-coke having high activity is produced from coal, which is used as a main raw material, and several kinds of coal and a binder are added thereto, resulting in a Loga index of 20-30%. Thus, a method of carbonization after strength adjustment and activation is disclosed. Japanese Patent Application Laid-Open No. 11-157822 discloses a method of dry distillation and activation after adjusting the blending of raw coal to a button index of 1.5 to 4. However, these Loga index and Button index are indices indicating strength such as wear resistance and the cohesiveness of blended coal, and by adjusting the blending of coal to a specific range of Loga index and Button index. Although activated carbon excellent in wear resistance and strength can be produced, it is not always possible to improve desulfurization performance or desulfurization denitration performance.
[0003]
Japanese Patent Application Laid-Open No. 11-349317 discloses a method for producing activated carbon excellent in strength and adsorption capacity by blending coal having volatile content and fluidity in the optimum ranges. However, in this method, there are various restrictions on the production conditions such as the main raw material, auxiliary raw material, heating temperature, and heating rate used, and it is difficult to obtain the main raw material and auxiliary raw material with little component fluctuation, and the production process is complicated. However, there is a problem in that activated carbon cannot be easily manufactured and the cost is increased.
[0004]
[Problems to be solved by the invention]
The present invention solves the above-described conventional problems, has high strength, high adsorption capacity (for example, SO _x adsorption capacity), has excellent desulfurization performance, and is used for circulation in a moving bed type dry desulfurization denitration process. The present invention was made to provide a method for producing activated carbon having a high strength enough to withstand.
[0005]
[Means for solving the problems]
As a result of intensive studies, the inventors of the present invention have found that in the method for producing activated carbon for desulfurization or activated carbon for desulfurization and denitrification using coal as a raw material, the coal particles are obtained from NMR (nuclear magnetic resonance) measurement results in the softening and melting temperature range of the coal By selecting and blending a component with a long transverse relaxation time, that is, the amount of mobile hydrogen component (melting index) within a specific range, extremely high desulfurization performance (for example, SO _x adsorption capacity) can be achieved. In addition, the inventors have invented a method for producing high-strength and robust activated carbon that can withstand long-term use in a moving bed.
[0006]
The present invention, which has been made to solve the above-mentioned problems, uses semi-coke obtained by subjecting coal to low temperature carbonization at a temperature of 300 to 600 ° C. as a main raw material, and cohesive coal as a secondary raw material. Calculated from the NMR measurement results at the temperature in the softened and melted state as the raw carbon of the semi-coke, which is the main raw material, in the production method of activated carbon to be activated carbon by performing carbonization and activation heat treatment on the molded product mixed with the agent The activated carbon production method is characterized in that coal having an amount of the mobile hydrogen component of 30% or less is used. In addition, as the coal having caking properties used as an auxiliary material in the above-described invention, activated carbon using coal in which the amount of the mobile hydrogen component calculated from the NMR measurement result at the temperature in the softened and melted state is 35 to 45% The manufacturing method is the invention according to claim 2.
[0007]
[Action]
In the method for producing activated carbon of the present invention, as the raw material coal for semi-coccus, which is the main raw material, the amount of the mobile hydrogen component calculated from the NMR measurement result at the softening and melting temperature is 30% or less. _{Since a} large number of micropores having a diameter of about 10 mm suitable for adsorbing _x molecules can be formed, activated carbon produced therefrom has high strength and excellent SO _x adsorption ability. In addition, as a raw material coal of a molded product that is a secondary raw material mixed in the semi-coccus as described above, which is the main raw material, a caking coal whose mobile hydrogen component amount calculated from the NMR measurement result is 35 to 45% By using the activated carbon, it is possible to produce activated carbon having a better appearance, high logger strength, and good SO _x adsorption ability.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described together with the process chart of the embodiment shown in FIG.
EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not restrict | limited at all by an Example. The amount of mobile hydrogen component, logger strength, desulfurization / denitration rate, and powdering rate due to ammonium sulfate production were determined by the following measurements.
[0009]
<Amount of mobile hydrogen component>
The target coal sample is loaded into a sample tube dedicated to the nuclear magnetic resonance apparatus. In addition, if a coal sample is several millimeters or less which is the size which fits into a sample tube, there will be no restriction | limiting in particular in the magnitude | size and shape. As a measurement method, the pulse width of 90 degrees hydrogen is 8 μsec, the echo time is 50 μsec to 3 msec, the repetition time is 5 msec to 1 sec, and the number of integration is 512 times. The data size is set to 512 points in the X direction, 512 points in the Y direction, and 1 to 512 points in the Z direction. At that time, while measuring the sample at 3 ° C / min, measurement is performed by applying a magnetic field gradient of 89 gauss / cm, 96 gauss / cm, and 107 gauss / cm to the X, Y, and Z axes in a short time. Obtain a hydrogen nuclear NMR imaging image of coal. Further, by performing the same measurement while raising the temperature, an NMR image image in which the coal is softened and melted is obtained. From the obtained image, the distribution at an appropriate lateral relaxation time and the abundance of the mobile hydrogen component are calculated. Here, the abundance of the mobile hydrogen component means the amount of the component having a transverse relaxation time of 100 μsec or more in the softening and melting temperature range. Here, the contents of the multiple pulses and the transverse relaxation time are described in JP-A-11-326248.
[0010]
<Logger strength>
Activated carbon can be charged and discharged, and 30g of activated carbon sample was placed in a rotating cylinder (φ200 x 70) with two baffle plates 30mm in height at the diagonal of the cylinder, and the cylinder was rotated at a rotation speed of 60rpm. It was rotated 1000 times. Thereafter, the activated carbon was taken out, fine particles were removed with a 3 mm mesh sieve, the weight ratio on the 3 mm sieve to the weight of the charged activated carbon was determined, and the logger strength was determined by the following equation (1). Fig. 7 shows the logger strength tester.
[Expression 1]

[0011]
<SO _x adsorption capacity>
Activated carbon sample 10cc synthesis gas to adjust the particle size to _{1 ~3mm (SO 2 2vol%,} O 2 5vol%, N 2 83vol%, H 2 O 10vol%) 3 at 100 ° C. at a flow rate of 3N liters / min to Contact for ₂ hours to adsorb SO ₂ gas. Thereafter, the mixture is heated at 400 ° C. for 1.5 hours under a N ₂ air flow. During this time, the SO ₂ gas adsorbed in the previous operation, which is accompanied and discharged by N ₂ , is absorbed in an aqueous solution of H ₂ O ₂ 3%. _{_{_{(SO 2 + H 2 O 2}}} → H 2 SO 4, it recovered as sulfate) and arsenazo III Method SO _x adsorption capacity of SO ₂ adsorption amount determined by neutralization titration with described absorbing solution to JIS K-0103 did. The SO ₂ adsorption amount per 1 g of activated carbon is expressed in units of mg / g-ac. In addition, it is ac: activated carbon (activated carbon).
[0012]
<Denitration rate>
Fill a cylindrical column with a diameter of 50 mm (denitration test reactor) with 170cc of activated carbon and heat to 90 ° C. Synthesis gas (SO ₂ 135ppm, NO 160ppm, NH ₃ 450ppm, O ₂ 10%, H ₂ O 10%, remaining N ₂ ) is heated to 90 ° C and brought into contact with the activated carbon packed bed at a flow rate of 2N liter / min. . The NO concentration on the inlet side and outlet side of the activated carbon packed bed after aeration of synthesis gas for 20 hours was measured, and the denitration rate was determined by the following equation (2).
[Expression 2]

[0013]
<Powdering rate due to ammonium sulfate production>
Fill a cylindrical column with a diameter of 50 mm (denitration test reactor) with 170cc of activated carbon and heat to 90 ° C. Synthesis gas (SO ₂ 135 ppm, NO 160 ppm, NH ₃ 450 ppm, O ₂ 10%, H ₂ O 10%, remaining N ₂ ) is brought into contact with the activated carbon packed bed at a flow rate of 2 N liter / min. After syngas is passed through for 100 hours, the entire amount of activated carbon is extracted from the cylindrical column, impregnated with water in a beaker, and gently stirred. Next, it is filtered through a 1 mm wire mesh and divided into filtrate (including activated carbon fine powder) and activated carbon pellets. The activated carbon fine powder is further filtered and extracted from the filtrate, dried and then weighed to obtain the activated carbon fine powder weight. The activated carbon pellets are heated at 400 ° C. for 1.5 hours under a N ₂ stream and regenerated, and then weighed to obtain the total weight of the activated carbon pellets after regeneration. The weight of the activated carbon fine powder and the weight of the activated carbon pellet after regeneration are totaled to obtain the total weight of the activated carbon after regeneration. The regenerated activated carbon pellets were passed through a 3 mm sieve, and the weight under the sieve and the activated carbon fine powder were added together to measure the weight of -3 mm, and the amount determined by the formula (3) was taken as the powdering rate due to the formation of ammonium sulfate. FIG. 8 shows an apparatus for measuring the denitration rate and the powdering rate by ammonium sulfate production.
[Equation 3]

[0014]
In FIG. 1, reference numeral 1 denotes a coal that is used as a raw coal for the main raw material semi-coke by performing low temperature carbonization. This coal is easily calculated from the NMR measurement results at a temperature corresponding to the softening and melting temperature range. The amount of the dynamic hydrogen component is 30% or less, preferably 15% or more and 30% or less. The mobile hydrogen component amount calculated from the NMR measurement results at the temperature corresponding to the softening and melting temperature range is set to the above-mentioned range. If the mobile hydrogen component amount exceeds 30%, it is effective for adsorption of SO _x molecules. This is because the micropore volume in the vicinity of 10 mm in diameter exhibiting the above decreases, while the effect of improving the SO _x adsorption capacity is saturated and less significant improvement cannot be expected even if it is less than 15%.
[0015]
The coal 1 is charged into the low temperature carbonization furnace 2 and has a oxygen concentration of 6% or less, and a residence time in the heating section in the furnace in a heating atmosphere of 300 ° C. to 600 ° C., preferably 400 ° C. to 550 ° C. Is made into semi-synthetic coke by low-temperature dry distillation under conditions of 15 minutes to 120 minutes, preferably 25 minutes to 80 minutes. The low-temperature carbonization conditions described above are sufficient to form a pore structure that should be supported as semi-coke when the temperature of the heating atmosphere is 300 ° C or less or the residence time in the furnace is 15 minutes or less. Therefore, semi-coke with poor pore structure in which only crystal water and some volatile components are volatilized becomes semi-coke. Even when trying to produce activated carbon as a raw material, the activation reaction with an activation gas such as steam does not proceed sufficiently in the activation process, and only activated carbon with poor SO _x adsorption ability can be obtained. If the residence time in the furnace exceeds 120 ° C. or more, disappearance of volatile components sufficient for pore structure formation proceeds, but graphitization of the substrate of the semi-coke itself proceeds excessively. Since graphite crystals have a stable structure in which carbon atoms constituting them are regularly arranged, if they are present in a large amount in activated carbon, not only the SO _x adsorption ability but also the catalytic activity for denitration is significantly reduced.
[0016]
Coal semi-coke as a main raw material, composed of its fine pores, because the coffin adsorption ability and strength of the SO _x in the activated carbon as a product by caking of some remaining raw material for the production of semi-coke Selection is a big problem. In order to support high SO _x adsorption ability as activated carbon, it is desirable that a large number of pores having a pore size suitable for adsorbing SO _x molecules in the state of semi-coke used as a main raw material are formed. Table 1 shows the amount of the mobile hydrogen component calculated from the NMR measurement results at a temperature corresponding to the softening and melting temperature range for 16 types of coal having different degrees of coalification. The softening and melting temperature of the target coal ranged from 350 ° C to 510 ° C.
[0017]
Moreover, it is desirable that the amount of mobile hydrogen component calculated from the NMR measurement result of caking coal blended as an auxiliary material is 35 to 45%. The reason for this is that when coal with a mobile hydrogen content of less than 35% is used as a secondary raw material, the resulting activated carbon has good appearance, but the logger strength is greatly reduced. When coal with a dynamic hydrogen content of more than 45% is used as a secondary raw material, the resulting activated carbon swells due to excessive caking and cracks occur, and many pores with large pore diameters are formed inside. This is because the strength decreases.
[0018]
[Table 1]

[0019]
FIG. 2 shows an example of the measurement results of the pore size distribution of semi-coke produced by heating the above 16 types of coal at 450 ° C. for 60 minutes. As a result of measuring the pore size distribution of the produced semi-coke, the coal can be classified into four types of A, B, C, and D based on the degree of development of the pore volume having a pore size of around 10%. That is, in semi-coke produced from coal belonging to Class A where the amount of mobile hydrogen component is 30% or less, from coal belonging to Class B, C, D where the amount of mobile hydrogen component exceeds 30% The semi-coke to be produced has a structure in which a micropore volume with a diameter of around 10 mm is developed even under the same heating conditions. In addition, in semi-coke produced from coal belonging to the B, C, and D classifications, the micropore volume around 10 mm in diameter decreases as the amount of mobile hydrogen component increases. In the category B, there is no expansion or expansion in appearance, but in the C and D classifications, there is a significant expansion, and the fracture surface of the semi-coke has coarse pores and the appearance of the semi-coke. Many coarse pores are generated due to swelling and expansion. In particular, in the D region, the coal particles swell so that the original shape of the coal cannot be stopped, and the particles are severely welded to each other, which is an operational problem for producing activated carbon.
[0020]
Next, FIG. 3 shows the measurement time of the heating time and the SO _x adsorption capacity of the produced semi-coke when low temperature carbonization is performed at 450 ° C. According to this result, semi-coke produced from coal belonging to Class A has the highest SO _x adsorption capacity, and the SO _x adsorption capacity decreases as the amount of the mobile hydrogen component in the coal increases. In other words, in order to effectively increase the SO _x adsorption capacity in the state of semi-coke used as the main raw material, it is necessary to increase the micropore volume around 10 mm in diameter as much as possible. It is desirable to use semi-coke obtained by subjecting coal belonging to the A region where the amount of the mobile hydrogen component obtained from the NMR measurement result of 30% or less to low temperature carbonization as a main raw material.
[0021]
This semi-coke is put into the pulverizer 3 as a main raw material and pulverized. Moreover, caking coal 4 used as an auxiliary material is also put into pulverizer 3 and pulverized. Next, the pulverized main raw material semi-coke and the auxiliary raw material caking coal 4 are mixed in a ratio of 9: 1 to 5: 5, preferably 8: 2 to 6: 4. And The mixed pulverized particles are transferred to a kneading machine 7. At that time, as a binder 5, coal-based or petroleum-based heavy oil such as tar and pitch, pulp production waste liquid, etc., and a molding aid 6 are added and kneaded. To do. This kneaded product is introduced into a molding machine 8 and formed into a large number of molded particles having a diameter of 5 to 20φ and a length of 5 to 30 mm. Each molded particle is then quantitatively measured in a carbonization activation furnace 9 such as a rotary kiln. And activated carbon having high strength and high desulfurization and denitrification ability by carbonizing and activating at a temperature of 750 to 900 ° C. while adding steam 10 and nitrogen gas 11 so that the activation proceeds effectively. Can be manufactured.
[0022]
FIG. 4 shows the relationship between the addition amount of the auxiliary raw material coal mixed with the main raw material and the logger strength. Here, semi-coke as the main raw material is obtained by heating Coal 1 of the brand belonging to the A region at 450 ° C. for 60 minutes. Activated carbon using caking coal that is blended as an auxiliary material in the A and B regions has a good product shape with no appearance of blistering or expansion, and a narrow particle size distribution. Although it is a structure, logger strength becomes a value significantly lower than ready-made activated carbon. In addition, activated carbon using caking coal blended as an auxiliary material belonging to the D region causes swelling due to excessive caking, many internal fracture surfaces have large pores, and logger strength is also off-the-shelf activated carbon. Lower value. -On the other hand, in the activated carbon using caking coal that is blended as a secondary raw material in the C region, the blending ratio of semi-coke as the main raw material and caking coal as the secondary raw material is 9: 1 to 5: 5. In the range, activated carbon having a particle size configuration having a good product shape and a narrow distribution, no bulging and cracking due to expansion, and higher logger strength than that of ready-made activated carbon can be obtained. That is, when trying to obtain robust activated carbon, caustic coal whose mobile hydrogen content calculated from NMR measurement results at a temperature corresponding to the softening and melting temperature range is in the range of 35% to 45%. It is important to select it as an auxiliary material.
[0023]
【Example】
FIG. 5 shows the relationship between the specific surface area of the activated carbon produced by the above method and the SO _x adsorption capacity together with a comparative example. Of the 16 types of coal with different mobile hydrogen components shown in Table 1, semi-coke produced by low-temperature carbonization of 6 types of coal belonging to the A region where the mobile hydrogen content is 30% or less. Was used as the main raw material to produce activated carbon. Coal belonging to area A is coarsely pulverized to a particle size of 50 mm or less, led to an externally heated rotary kiln, and dry-distilled so that the oxygen concentration is 2% or less, the heating atmosphere temperature is 450 ° C, and the residence time in the furnace is 60 minutes. Semi-finished coke was made, and then the semi-finished coke was pulverized by a pulverizer 3 to be a main raw material. At this time, among the 16 types of coal with different mobile hydrogen components shown in Table 1, bituminous coal with a mobile hydrogen component melting index of 40.2% was pulverized by the pulverizer 3 and used as an auxiliary material. did. These main raw materials and auxiliary raw materials are blended so as to have a mass ratio of 8: 2, and 20% by mass of coal-based soft pitch is added as

binder

5 and 15% by mass of water is added as molding aid 6, and kneaded. What was sufficiently kneaded by the machine 7 was molded into a cylindrical shape having a diameter of 10φ and a length of 10 mm by the extrusion molding machine 8. This molded product is led to an externally heated mouth-piece tally kiln, in an atmosphere with an oxygen concentration of 1% and an activated steam blow rate of 1.Okg per kg of molded product, the maximum temperature of the molded product reached 830 ° C and the average heating rate is Activated charcoal was produced by heating, carbonizing and activating at 18 ° C / min at a temperature above 800 ° C for 40 min. The activated carbon thus obtained has an logger strength of 97.9 to 98.8%, SO _x adsorption capacity of 72.0 to 80.2mg / g-ac, denitration rate of 48%, and powdering rate of 0.01% by the formation of ammonium sulfate. It was excellent.
[0024]
[Comparative Example 1]
Of the 16 types of coal with different mobile hydrogen components shown in Table 1, low-temperature carbonization can be performed on 2 types of coal belonging to the B region where the mobile hydrogen content is more than 30% and less than 35%. Activated carbon was produced using the produced semi-finished coke as the main raw material. Coal belonging to region B is coarsely pulverized to a particle size of 50 mm or less, led to an external heating rotary kiln, dry distillation so that the oxygen concentration is 2% or less, the heating atmosphere temperature is 450 ° C and the residence time in the furnace is 60 minutes The semi-coke was then pulverized by a pulverizer 3 and used as a main raw material. At this time, among 16 types of coal with different mobile hydrogen components shown in Table 1, bituminous coal with a melting index of mobile hydrogen component of 40.2% was pulverized with a pulverizer as an auxiliary material. . Blended coal containing these main raw materials and auxiliary raw materials in a mass ratio of 8: 2, coal-based soft pitch as

binder

5, 20% by mass with respect to the blended coal, and water as molding aid 6 15 The mass% added and sufficiently kneaded in the kneader 7 was molded into a cylindrical shape having a diameter of 10φ and a length of 10 mm by the extruder 8. This molded product is led to an externally heated rotary kiln. In an atmosphere with an oxygen concentration of 1% and an activated steam blowing rate of 1.0 kg per 1 kg of molded product, the maximum achieved temperature of the molded product is 830 ° C and the average heating rate is 18 ° C / Activated carbon was produced by heating, carbonizing, and activating so that the holding time at min, 800 ° C. or higher was 40 min. Activated carbon thus obtained is logger strength was sufficient and 97.1 to 98.2% SO _x adsorption capacity 45.5~47.Omg / g-ac, denitrification rate 38%, powdering rate by ammonium sulfate product 0.9%, which was significantly inferior to the examples.
[0025]
[Comparative Example 2]
Among the 16 types of coal with different mobile hydrogen component amounts shown in Table 1, low-temperature carbonization can be performed on 6 types of coal belonging to the C region where the mobile hydrogen component amount is 35% to 45%. Activated carbon was produced using semi-sintered coke as the main raw material. Coal belonging to region C is coarsely pulverized to a particle size of 50 mm or less, led to an external heating type single tally kiln, dry distillation so that the oxygen concentration is 2% or less, the heating atmosphere temperature is 450 ° C, and the residence time in the furnace is 60 minutes. The semi-coke was then pulverized with a pulverizer as a main raw material. At this time, among 16 types of coal with different mobile hydrogen components shown in Table 1, bituminous coal with a melting index of mobile hydrogen component of 40.2% was pulverized with a pulverizer as an auxiliary material. . Blended coal blended with these main raw materials and auxiliary raw materials in a weight ratio of 8: 2, blended with coal-based soft pitch as

binder

5 and 20% by mass of blended coal with water as molding aid 6. 15% by mass with respect to the mixture, which was sufficiently kneaded by the kneader 7, was molded into a circular shape having a diameter of 10φ and a length of 10 mm by the extruder 8. This molded product is led to an externally heated rotary kiln. In an atmosphere with an oxygen concentration of 1% and an activated steam blowing rate of 1.0 kg per 1 kg of molded product, the maximum achieved temperature of the molded product is 830 ° C and the average heating rate is 18 ° C / Activated carbon was produced by heating, carbonizing and activating the product so that the holding time at min, 800 ° C. or higher was 40 min. Activated carbon obtained in this way, logger strength from 92.0 to 94.8% SO _x adsorption capacity 33.0~36.Omg / g-ac, denitrification rate 38%, a powdering ratio of 1.2% with ammonium sulfate product, either The performance of was also significantly inferior to the examples.
[0026]
[Comparative Example 3]
Of the 16 types of coal with different mobile hydrogen components shown in Table 1, semi-coke obtained from low temperature carbonization of 3 types of coal belonging to the D region where the amount of mobile hydrogen components exceeds 45%. Activated carbon was produced as the main raw material. Coal belonging to region D is coarsely pulverized to a particle size of 50 mm or less, led to an externally heated rotary kiln, dry-distilled so that the oxygen concentration is 2% or less, the heating atmosphere temperature is 450 ° C, and the residence time in the furnace is 60 minutes. After making semi-finished coke, the semi-finished coke was pulverized with a pulverizer to obtain a main raw material. At this time, among the 16 types of coal with different mobile hydrogen components shown in Table 1, bituminous coal with a mobile hydrogen component melting index of 40.2% was pulverized by the pulverizer 3 and used as an auxiliary material. did. A blended coal containing these main raw materials and auxiliary raw materials in a weight ratio of 8: 2, coal-based soft pitch as a binder 5 is 20% by mass with respect to the blended coal, and water is 15 masses as a molding aid 6. % And the mixture kneaded sufficiently in the kneader 7 was molded into a cylindrical shape having a diameter of 10φ and a length of 10 mm by the extruder 8. This molded product is led to an external heating type single tally kiln. In an atmosphere with an oxygen concentration of 1% and an activated steam blowing rate of 1.0 kg per 1 kg of the molded product, the maximum achieved temperature of the molded product is 830 ° C and the average heating rate is 18 Activated carbon was manufactured by heating, carbonizing, and activating at 40 ° C./min, holding time at 800 ° C. or higher to 40 min. The activated carbon thus obtained has a logger strength of 90.2 to 92.1%, an SO _x adsorption capacity of 10.8 to 12.0 mg / g-ac, a denitration rate of 5%, and a powdering rate of 1.0% by the formation of ammonium sulfate. The performance was also significantly inferior compared to the examples.
[0027]
Although in FIG. 5 shows the improvement in adsorption capacity of the SO _x by increasing the specific surface area by the micropores formed, it can be seen that the activated carbon produced by coal A region having a large specific surface area has a high desulfurization performance. As shown in FIG. 6, such a specific surface area greatly varies depending on the heating atmosphere temperature in the low temperature dry distillation, and therefore it is desirable to set the dry distillation temperature appropriately.
[0028]
【The invention's effect】
As described above, the activated carbon production method of the present invention has a mobile hydrogen component amount calculated from the NMR measurement result at the softening and melting temperature as a coal that is subjected to low-temperature carbonization to form semi-coke as the main raw material. By using less than 30%, it is possible to form a large number of micropores with a diameter of about 10 mm suitable for adsorbing SO _x molecules, and the activated carbon produced therefrom has high strength and desulfurization performance (for example, SO _x adsorption). Performance). In addition, as a secondary raw material mixed with semi-coke, which is the main raw material, by using caking coal whose mobile hydrogen content calculated from the NMR measurement results is 35 to 45%, the appearance is further improved and high. It is possible to produce activated carbon having logger strength, good desulfurization (SO _x adsorption capacity) performance, and a powdering rate due to low ammonium sulfate production. Further, an excellent activated carbon for desulfurization and denitrification is obtained.
[Brief description of the drawings]
FIG. 1 is a flowchart of a process for producing activated carbon.
FIG. 2 is an explanatory diagram showing the volume distribution of micropores of four types of coal classified by the amount of mobile hydrogen component.
FIG. 3 is a graph showing the relationship between the low-temperature carbonization time and the SO _x adsorption capacity of semi-coke.
FIG. 4 is a diagram showing the relationship between the type and blending ratio of coal having caking properties, which is an auxiliary raw material, and logger strength.
FIG. 5 is a relationship diagram showing an improvement in SO _x adsorption capacity by increasing the kind of raw coal of semi-coke as a main raw material and the specific surface area.
FIG. 6 is a relational diagram showing a change in specific surface area of activated carbon depending on the temperature of low temperature carbonization.
FIG. 7 is an explanatory diagram of a logger strength tester.
FIG. 8 is an explanatory diagram showing a method for measuring a denitration rate and a powdering rate by ammonium sulfate production.
[Explanation of symbols]
1 Coal for semi-coke 2 Low temperature distillation furnace 3 Crusher 4 Caking coal 5 Binder 6 Molding aid 7 Kneading machine 8 Molding machine 9 Carbonization and activation furnace 10 Steam 11 Nitrogen gas 12 Product

Claims

Carbide and activation treatment is performed on a molded product of semi-formed coke, which has been subjected to low temperature carbonization at 300 to 600 ° C, as a main raw material, and cohesive coal as a secondary raw material, and these are mixed and molded together with a binder. In the method for producing activated carbon to be activated carbon, as the raw coal of semi-coke, which is the main raw material, coal whose amount of mobile hydrogen component calculated from NMR measurement results at a temperature in a softened and melted state is 30% or less The manufacturing method of activated carbon characterized by using.

The activated carbon according to claim 1, wherein coal having an amount of mobile hydrogen component calculated from NMR measurement results at a temperature in a softened and melted state is 35 to 45% as the coal having caking properties as an auxiliary material. Manufacturing method.