JP3556645B2 - Exhaust gas treatment method and exhaust gas treatment device - Google Patents

Description

【００３１】
式（１）中、Ｎは、排ガス中の窒素からプラズマにより生成した窒素ラジカルであり、ＮＯは排ガス中に主として含まれる一酸化窒素である。また、多次のＮＯ_２といった窒素酸化物は、上述した窒素ラジカルによって一酸化窒素に分解され、最終的に上記式（１）の反応によって窒素と酸素とに分解される。この窒素および酸素は、未燃焼炭素などとともに後流側の抵抗加熱手段５に供給される。また、排ガス中に含まれるダストは、プラズマ発生手段４によって発生するプラズマにより帯電し、周部電極８などに付着させて排ガス中から除去することができる。
【００３２】
図１に示す中央部電極７は、排ガスの供給側に向いた先端が尖った形状とされ、排ガスの流れに対して抵抗が小さくなるような形状とされている。また、周部電極８は、周部電極８の一部分が中央部電極７に近接するような形状とされている。このようにすることで、中央部電極７から周部電極８に向けて効率良く放電させることができ、適切に排ガス中にプラズマを発生させることができる。また、周部電極８には、高圧電流が流れるため、中空部材３ａと周部電極８との間に木やセラミックスなどの絶縁物を配設し、中空物質３ａに触れても感電しないようにすることができる。また、プラズマ発生手段４に用いる中央部電極７および周部電極８としては、導電性のある材質であればいかなるものでも良く、例えば鉄、銅、銀などを用いることができる。
【００３３】
図１に示す抵抗加熱手段５には、中空部材３ｂの内部に所定間隔で配設された螺旋形状の抵抗加熱板５ａが用いられ、排ガスが流れる方向に複数設置されている。また、抵抗加熱板５ａの中央には、それぞれの抵抗加熱板５ａを連結するとともに、電流を各抵抗加熱板５ａに供給するための中央部軸部材１０ａと、螺旋形状とされた抵抗加熱板５ａを通して流れた電流を図示しない電源に戻すための端部軸部材１０ｂとが配設されている。これら中央部軸部材１０ａおよび端部軸部材１０ｂには、図示しない電源に接続するための導線１１ａ、１１ｂが接続され、電流を供給または戻すことができるようになっている。図１に示す実施の形態では、中央部軸部材１０ａの中央部に複数の抵抗加熱板５ａ、その両端部に多孔板１２ａ、１２ｂが配置されるように設けられている。図１に示す多孔板１２ａ、１２ｂは、複数の抵抗加熱板５ａの間に充填する充填物６が流出しないようにストッパとして設けられている。
【００３４】
図１に示す充填物６は、抵抗加熱板５ａの間、抵抗加熱板５ａと多孔板１２ａ、１２ｂとの間に充填されている。また、図１に示す充填物６は、抵抗加熱板５ａに隣接するように密に充填され、抵抗加熱板５ａによって発生した熱が充填物６全体に伝わるようになっている。また、充填物６を間に充填した抵抗加熱板５ａおよび多孔板１２ａ、１２ｂを収容するセラミックス製の円筒部材１３が中空部材３ｂの内部に配設され、中空部材３ｂと円筒部材１３との間にスチールウールといった断熱材１４が設けられている。抵抗加熱板５ａに供給された電流は、外部が絶縁物であるセラミック製の円筒部材１３であるため、適切に端部軸部材１０ｂを通して図示しない電源に戻される。また、抵抗加熱板５ａによって発生する熱は、充填物６および円筒部材１３に伝えられる。本発明においては、円筒部材１３の外面側に設けられる断熱材１４により放熱が抑制されるようになっている。
【００３５】
プラズマ処理された排ガスは、中空部材３ｂに供給され、多孔板１２ａを通して充填物６の層へ供給される。充填物６の層に供給された排ガスは、抵抗加熱板５ａおよび充填物６の層を通し、多孔板１２ｂを通して大気中に放出される。通過する際、抵抗加熱板５ａおよび加熱された充填物６に接触することで、排ガスは、加熱され、排ガス中の未燃焼炭素が燃焼される。本発明においては、充填物６の層を通して充分に接触させることにより所定温度まで加熱して燃焼される。
【００３６】
図１においては、本発明の排ガス処理装置１が取り外し可能なようにフランジ２により接続しているが、外部へ排ガスが漏れることなく本発明の排ガス処理装置１へ供給できるのであればいかなる接続手段でも用いることが可能である。さらに、本発明の排ガス処理装置１と接続する管との接続サイズが異なる場合には、レデューサを用いて接続することができる。また、本発明に用いる中空部材３ｂは、図１に示すように中空円筒状とされていなくてもよく、中空であればいかなる形状であっても良い。中空部材３ｂの材質は、内部を通過する排ガスの温度に耐えうるものであればいかなるものでもよく、例えば、ステンレス鋼、炭素鋼、セラミックスなどを用いることができる。また、内部温度を保持するために、中空部材３ｂの外側面または内側面にスラグウールやロックウールといった断熱材を設けることができる。
【００３７】
図１に示す抵抗加熱手段５は、上述したように螺旋形状の複数の抵抗加熱板５ａと、抵抗加熱板５ａの中央部に挿通して設けられる中央部軸部材１０ａと、中央部から螺旋形状とされた抵抗加熱板５ａを通して流れた電流を図示しない電源に戻すために、抵抗加熱板５ａの端部に挿通して設けられる端部軸部材１０ｂと、抵抗加熱板５ａに電流を供給する導線１１ａ、１１ｂとから構成されている。抵抗加熱板５ａは、排ガスを通すために螺旋形状の通路１５が形成されていて、また、抵抗加熱板５ａは、電流を供給することにより表面温度を上昇させることが可能な材質から形成され、例えば、電気抵抗の高い材質のものを用いることができる。本発明においては、ニッケル−クロム合金、ニッケル−クロム−鉄合金などを用いることができる。通路１５は、適切な量の排ガスを流すことができ、内部に充填される充填物６が通り抜けない大きさとすることができる。また、抵抗加熱板５ａは、排ガスを加熱するとともに内部に充填された充填物６も加熱する。これによって、例えば、自動車の内燃機関、各種ボイラあるいはゴミ焼却設備などの一次燃焼手段で残存した未燃焼炭素を加熱燃焼および窒素酸化物を分解することにより、無害化して処理することができる。
【００３８】
本発明においては、排ガス中の未燃焼炭素を完全に燃焼させるために排ガスの温度を２００℃〜８００℃とすることができる。本発明において排ガスの温度は、抵抗加熱板５ａに供給する電流量を調節することより２００℃〜８００℃に調節することができる。本発明の排ガス処理装置１を車両に接続する場合において、プラズマ発生手段４に供給する電流は、ディストリビュータからの高電圧点火電流を用いることができ、また抵抗加熱手段５に電流を供給するための電源としては、バッテリーを用いることができる。
【００３９】
本発明において充填物６は、排ガスを接触させて充分に加熱するためには小さいもののほうが好ましいが、小さいものの場合には抵抗が増大し、本発明の排ガス処理装置１の上流側の上述した一次燃焼手段に負荷がかかることになる。したがって、充分な接触と、排ガスの流れの抵抗を考慮し、適切な大きさの充填物６を用いることができる。本発明においては、充填物６として耐熱強度の高いセラミックスまたは白金または白金を含有するセラミックスなどを用いることができる。具体的には、耐熱性を有し、アルミナ含有量９９質量％以上のアルミナボールやアルミナを坦体とした白金触媒を挙げることができる。さらに、Ｎ_２Ｏを分解する触媒としてアルミナ坦持またはゼオライト坦持ロジウム触媒を用いることもできる。また、上記ロジウムに代えてコバルト銅、パラジウムまたはバナジウムなどを含む触媒を用いることもできる。本発明においては、密に充填しやすい球状の充填物６が好ましく、径は、４ｍｍ〜１０ｍｍのものを用いることができる。さらに、本発明においては、伝熱性を高めるために充填物６を密に充填するほうが好ましい。本発明の排ガス処理装置１の抵抗加熱手段５および加熱された充填物６に接触することによって、主に以下の式（２）に示す反応が起こる。
【００４０】
【化２】

【００４１】
Ｃは排ガス中の未燃焼炭素であり、Ｏ_２は排ガス中に含まれる余剰酸素である。また、排ガス中の窒素酸化物は、上述したように排ガス中の水蒸気が過熱蒸気となり、過熱蒸気の作用によって窒素と酸素とに分解される。窒素酸化物の分解により得られた酸素は、上記式（２）の反応に使用することができる。上記式（２）に示す反応および窒素酸化物の分解反応により生成した二酸化炭素および窒素は、前流側でプラズマ処理された窒素および酸素および一次燃焼手段で生じた水蒸気といったその他の排ガス成分とともに大気中へ放出される。
【００４２】
さらに、充填物６が流出しないように設けられる多孔板１２ａ、１２ｂは、充填物６の径より小さい穴や孔をもつもので、かつ加熱する温度に耐えうる材質のものであればいかなる形状のものでも用いることができる。また、多孔板１２ａ、１２ｂは、排ガスが流れる方向に対向するように配設され、多孔板１２ａ、１２ｂに設けられた穴を通して排ガスが流れるようになっている。本発明において多孔板１２ａ、１２ｂは、ステンレス鋼製またはセラミックス製のものを用いることができる。また、本発明においては、多孔板に限らず、排ガスを通すことができ、内部に充填した充填物６が流出しないように押さえることができるものであればいかなるものであっても良い。
【００４３】
図１に示す円筒部材１３は、複数の抵抗加熱板５ａおよび多孔板１２ａ、１２ｂの外周部と中空部材３ｂとの間に配設されていて、抵抗加熱板５ａに供給する電流が適切に流れるように設けられている。本発明においては、中空部材３ｂがセラミックス製などの絶縁物で作製されている場合には、円筒部材１３は設けなくても良い。また、円筒部材１３は、内部に充填されている充填物６や抵抗加熱板５ａによって加熱されるため、円筒部材１３と中空部材３ｂとの間にスチールウールなどの断熱材１４が設けられている。本発明においては、排ガスが適切に充填物６間を通して流れるように遮断でき、高温においても燃焼することなく、かつ断熱することができるものであれば、いかなる材質の断熱材を用いることができる。また、多孔板１２ｂおよび円筒部材１３は、中空部材３ｂ内部の所定位置に配設されるように支持部１６に連結されている。支持部１６は、中空部材３ｂの所定位置に設けられ、複数の抵抗加熱板５ａ、多孔板１２ａ、１２ｂおよびそれらを連結し、各抵抗加熱板５ａに電流を供給する中央部軸部材１０ａおよび端部軸部材１０ｂは、円筒部材１３とともにボルトおよびナットといった締結手段によって支持部１６に締結されている。本発明においては、支持部１６と多孔板１２ｂとの間に絶縁物を設置し、中央部軸部材１０ａに連結された多孔板１２ｂを通して中空部材３ｂに電流が流れないようにすることができる。
【００４４】
図１に示す排ガス処理装置１は、抵抗加熱手段５の後流側にさらに捕集部材１７が設けられ、抵抗加熱手段５によって燃焼することができずに残存する未燃焼物質を捕集することができる。図１に示す捕集部材１７は、残存する未燃焼物質を捕集できるのであればいかなるメッシュサイズであっても良い。また、捕集部材１７は、上述したように未燃焼炭素を燃焼させるために排ガスを２００℃〜８００℃に加熱するため、これらの温度に耐えうる材質のものを用いることができる。中空部材３ｂの内部の所定位置に設けられた支持部１６によって支持することができる。
【００４５】
図２は、本発明の排ガス処理装置１に用いる抵抗加熱板５ａを例示した図である。図２に示す抵抗加熱板５ａは、排ガスが流れる方向に対向するように配設され、螺旋形状の隙間を通して排ガスが流れるようになっている。抵抗加熱板５ａの隙間を通過する際、抵抗加熱板５ａに接触した排ガスは加熱されるようになっている。また、抵抗加熱板５ａは、隣接して充填される充填物６を所定温度に加熱する。図２に示す実施の形態では、中央部に図１に示す中央部軸部材１０ａを挿通させて連結するための第１の挿通孔１８と、螺旋形状とされた加熱部１９の端部に設けられ、図１に示す端部軸部材１０ｂを挿通して連結するための第２の挿通孔２０とが設けられている。本発明においては、抵抗加熱板５ａに電流した場合、充分に電気抵抗を与えることにより表面温度を上昇させる効率を向上させることができ、例えば図２に示すような螺旋形状の加熱部１９とすることができる。本発明においては、図２に示す構造に限らず、充分に電気抵抗を与えることができる構造であればいかなる構造であっても良い。
【００４６】
図３は、本発明の排ガス処理装置１に用いる抵抗加熱手段５を例示した図である。図３に示す抵抗加熱手段５は、所定間隔で抵抗加熱板５ａが３つと、その両端に多孔板１２ａ、１２ｂが配設されている。各抵抗加熱板５ａおよび多孔板１２ａ、１２ｂは、中央部軸部材１０ａと、端部軸部材１０ｂとによって連結されている。排ガスは、多孔板１２ａから複数の抵抗加熱板５ａを通して多孔板１２ｂに向けて流れる。また、抵抗加熱板５ａに供給される電流は、中央部軸部材１０ａを通して各抵抗加熱板５ａに供給される。各抵抗加熱板５ａに供給された電流は、螺旋形状とされた加熱部１９を通して各抵抗加熱板５ａの端部に向けて流れ、端部に設けられた端部軸部材１０ｂを通して図示しない電源に戻される。図３に示す実施の形態では、多孔板１２ａ、１２ｂに電流が供給されないように中央部軸部材１０ａおよび端部軸部材１０ｂと多孔板１２ａ、１２ｂとの間に絶縁物を設けることができる。多孔板１２ａと抵抗加熱板５ａとの間、抵抗加熱板５ａ同士の間、抵抗加熱板５ａと多孔板１２ｂとの間には、図１に示す充填物６が隣接して密に充填される。多孔板１２ａ、１２ｂに設けられる複数の穴２１は、充填物６が流出しない大きさとすることができる。
【００４７】
図４は、本発明の排ガス処理装置１の第２の実施の形態を示した図である。図４に示す実施の形態では、抵抗加熱手段５は図１に示す装置と同様とされ、プラズマ発生手段４が異なった形状とされている。図４に示すプラズマ発生手段４は、中空部材３ａの長さ方向に長くされた中央部電極７と、中央部電極７から等間隔で、中空部材３ａの内周に中央部電極７に対向して設けられた周部電極８と、周部電極８と中空部材３ａとの間には、絶縁物２２が設けられている。図４に示す中央部電極７には、導線９ａから電圧が印加され、中央部電極７と周部電極８との間を流れる排ガス中にプラズマを発生させる。排ガスを通して周部電極８に流れた電流は、導線９ｂを通して図示しない電源に戻される。本発明においては、導線９ｂをアースなどに接続することもできる。排ガスは、プラズマ処理されることにより、上述した式（２）の反応を伴って窒素酸化物が窒素と酸素とに分解され、未燃焼炭素やダストが帯電して電極や後流側に配設される抵抗加熱手段５に付着したり、充填物６に捕捉される。図４に示す中央部電極７は、コロナ放電をする電極を用いることもできるが、低圧の排ガス中に効果的にプラズマを発生させるためにグロー放電をする電極を用いることが好ましい。また、本発明においては、放電する電極を周部電極８に用い、設置する電極を中央部電極７に用いることもできる。
【００４８】
図４に示す実施の形態では、プラズマ処理された排ガス中に含まれる帯電した未燃焼炭素やダストは、上述したように抵抗加熱板５ａや充填物６に付着する。抵抗加熱板５ａおよび充填物６は、所定温度に加熱され、付着した未燃焼炭素やダストは燃焼される。また、排ガス中に含まれる帯電していない未燃焼炭素は、抵抗加熱板５ａおよび加熱された充填物６に接触することにより加熱され、上述した式（１）の反応を伴って燃焼する。プラズマ処理および燃焼処理された排ガスは、捕集部材１７によってさらに粒子状汚染物質を除去した後、大気中に放出される。
【００４９】
図５は、本発明の排ガス処理装置１の第３の実施の形態を示した図である。図５に示す排ガス処理装置１は、図１または図４に示す装置にさらにアルカリ水溶液２４を収容した容器２５が設けられている。図５に示す実施の形態では、車両やゴミ処理設備などから取り出された排気管２６と容器２５から取り出された管２７ａとが接続され、管２７ａの先端部は、アルカリ水溶液２４中に浸漬されている。容器２５は、内部のガスが外部に漏洩しないように封止された構造とされていて、容器２５の上部に接続された管２７ｂを通して図１に示すプラズマ発生手段４および抵抗加熱手段５を有する装置に排ガスが供給されるようになっている。車両やゴミ処理設備などから排出される排ガスには、上述した成分のほか、硫黄酸化物（ＳＯ_ｘ）、炭化水素などが微量に含まれており、これらが大気汚染の原因にもなっている。図５に示すアルカリ水溶液２４中に排ガスを通すことにより未燃焼炭素、ＮＯ_２といった窒素酸化物、硫黄酸化物、炭化水素を除去することができる。
【００５０】
本発明に用いることができるアルカリ水溶液２４としては、炭酸ナトリウム水溶液や水酸化ナトリウム水溶液を挙げることができる。また、炭酸ナトリウム水溶液および水酸化ナトリウム水溶液中の炭酸ナトリウムおよび水酸化ナトリウムの濃度としては、いかなる濃度であっても良いが、１〜１０質量％のものを用いることができる。例えば、炭酸ナトリウム水溶液を用いる場合、未燃焼炭素は、炭酸ナトリウム水溶液中に懸濁させることができ、ＮＯ_２は、炭酸ナトリウムと化学反応することによりＮａＮＯ_３を生成し、硫黄酸化物は、炭酸ナトリウムと化学反応することによりＮａＳＯ_４を生成し、炭化水素は、温度の低下とともに液化される。しかしながら、アルカリ水溶液２４に溶解しないＮＯや一部の未燃焼炭素などは、その他の成分、窒素、酸素、二酸化炭素、一酸化炭素などとともに管２７ｂを通して図１に示すプラズマ発生手段４を備える中空部材３ａに供給される。プラズマ発生手段４により、上述したように排ガス中のＮＯは、式（１）による分解反応によって窒素と酸素とに分解され、未燃焼炭素などの粒子状汚染物質が帯電する。プラズマ処理された排ガスは、後流に設けられた図１に示す抵抗加熱手段５および抵抗加熱手段５によって加熱された充填物６によって加熱され、排ガス中の未燃焼炭素や一酸化炭素が燃焼される。このようにして処理された排ガスは、窒素、酸素、二酸化炭素および水蒸気を主としたクリーンな排ガスとして大気中に排出される。
【００５１】
図５に示す容器２５としては、いかなる形状、排ガスを処理する量によっていかなる大きさのものであっても良い。容器２５の材質としては、アルカリ水溶液２４によって腐食しないものであればいかなるものでも用いることができるが、例えば、ステンレス鋼、強化プラスチックなどの材料を挙げることができる。また、容器２５の内部の構造は、適切に排ガスとアルカリ水溶液２４とが接触し、上述した化学反応などによって未燃焼炭素、硫黄酸化物、ＮＯ_２、炭化水素を除去することができる構造とすることができる。本発明においては、図５に示すように管２７ａの先端部を、容器２５の底部に向けて配置し、排ガスが上部空間に向けて上昇するような構造とすることができる。さらに、図５に示すように容器２５の底部は、排ガスの噴射に適合させた溝を設けた構造とすることもできる。本発明においては、図５に示すようにプラズマ発生手段および抵抗加熱手段の両方が設けられた構造でなくても良く、排ガス中の汚染物質により抵抗加熱手段のみを用いることもできる。
【００５２】
図６は、本発明の排ガス処理装置１の第４の実施の形態を示した図である。図６に示す排ガス処理装置１は、図１に示す排ガス処理装置と同様の構造とされていて、さらに中空部材３ｂに空気を供給するための空気孔２８と、空気供給手段２９とが設けられている。プラズマ処理された排ガス中には、酸素が１０体積％〜１８体積％しか含まれておらず、充分な酸素がない場合には、抵抗加熱板５ａおよび加熱した充填物６により加熱しても充分に燃焼されないこととなる。図６に示す排ガス処理装置１は、空気供給手段２９から空気孔２８を通して空気を供給することにより燃焼に必要とされる酸素を与えることができる。本発明においては、燃焼に必要とされる量の空気を供給することができ、具体的には、排ガス中の酸素濃度を測定するなどして適切な量の空気を供給することができる。酸素濃度は、プラズマ発生手段４と抵抗加熱板５ａとの間の位置における排ガス中の酸素濃度を測定することができる。また、本発明においては、図６に示す構造に限らず、抵抗加熱手段５の後流側にも空気孔２８を設けて空気を供給し、排ガス温度を下げるとともに、排出される排ガス中の汚染物質の濃度を低減させることもできる。
【００５３】
図７および図８を使用して本発明の排ガスの処理方法について詳細に説明する。図７は、図１に示す排ガス処理装置１をディーゼルエンジンを有する車両の排気管３０に接続したところを示した図である。図７に示す排ガス処理装置１は、フランジ２などによって排気管３０に連結されていて、車両から放出される高温の排ガスが供給される。ガソリン車においては、粒子状汚染物質の濃度が低く、その代わりにＮ_２Ｏなどの窒素酸化物が多く含まれ、ディーゼル車においては、未燃焼炭素などの粒子状汚染物質が多く含まれている。まず、排ガスを中空部材３ａに供給する前に、図示しない電源から中央部電極７に電圧を印加する。次に、中空部材３ａに排ガスを供給し、排ガスが中央部電極７と周部電極８との間を通過する際に発生するプラズマによって排ガス中の窒素酸化物が分解し、未燃焼炭素やダストといった粒子状汚染物質が帯電する。また、排ガス中に発生したプラズマにより中央部電極７から周部電極８に向けて電流が流れ、図示しない電源に向けて電流が戻される。プラズマ処理された排ガスは、中空部材３ａに連結される中空部材３ｂに向けて供給され、プラズマ処理されることにより発生した酸素が排ガス中の一酸化炭素などと反応する。
【００５４】
また、予め抵抗加熱板５ａに図示しない電源から電流を供給し、抵抗加熱板５ａを加熱するとともに、抵抗加熱板５ａに隣接する充填物６も所定温度まで加熱する。所定温度まで抵抗加熱板５ａおよび充填物６を加熱した後、排ガスを供給することができる。上述したようにプラズマ処理された排ガスは、中空部材３ｂに供給され、多孔板１２ａを通して加熱された充填物６へと送入される。排ガスは、充填物６の隙間を通して流れることにより加熱され、未燃焼炭素といった未燃焼成分が燃焼する。排ガスは、充填物６や抵抗加熱板５ａに接触するとともに抵抗加熱板５ａに設けられた通路１５を通して流れ、さらに充填物６や抵抗加熱板５ａに接触しながら充填物６の隙間および抵抗加熱板５ａの通路１５を通して流れることにより充分に加熱および未燃焼成分の燃焼が行われる。中空部材３ｂにおいては、図６に示すように空気孔２８および空気供給手段２９を設けることによりさらに効率良く燃焼させることができる。この場合、充填物６を所定温度まで加熱した後、空気供給手段２９から空気を供給することができ、その後に排ガスを供給することができる。また、抵抗加熱手段４を通過後の排ガスは、捕集部材１７によって残存する粒子状汚染物質をさらに充分に除去し、大気中に排出される。
【００５５】
図８は、図５に示す排ガス処理装置１を車両の排気管に接続したところを示した図である。図８に示す排ガス処理装置１は、フランジ２などによって車両の排気管３０に連結されていて、排ガスは、排気管３０、管３１を通して容器２５の内部に供給される。管３１は、容器２５の底部に向けて配設され、容器２５の内部には所定高さまで炭酸ナトリウム水溶液といったアルカリ水溶液２４が収容されている。まず、上述したようにプラズマ発生手段４の中央部電極７に電圧を印加し、抵抗加熱板５ａに電流を供給して充填物６を加熱する。所定温度まで加熱した後、排ガスを本発明の排ガス処理装置１に供給することができる。アルカリ水溶液２４に供給された排ガスは、排ガス中の未燃焼炭素、ＮＯ_２、硫黄酸化物、炭化水素などがアルカリ水溶液２４によって除去される。容器２５を出た排ガスは、図８に示すようにプラズマ処理することによりＮＯなどのアルカリ水溶液２４によって除去されない物質を分解し、除去することができる。また、プラズマ処理においては、未燃焼炭素やダストなどの粒子状汚染物質を帯電させて電極や後流側に設けられた抵抗加熱板５ａおよび加熱された充填物６に付着される。電極に付着した粒子状汚染物質は、排ガスが供給されることにより剥がれ落ち、後流側の抵抗加熱板５ａおよび充填物６に付着する。プラズマ処理された排ガスは、抵抗加熱板５ａに接触するまでの間、プラズマ処理によって生成した酸素が一酸化炭素などの未燃焼物質と反応する。また、排ガスは、多孔板１２ａを通して充填物６の層に供給される。充填物６の層に供給された排ガスは、充填物６に接触しながら隙間を通して流れ、また抵抗加熱板５ａに接触するとともに通路１５を通して流れて多孔板１２ｂから排出される。この間において排ガスは、充分に加熱され、排ガス中に含まれる未燃焼物質が燃焼される。また、さらに残存した粒子状汚染物質は、捕集部材１７に捕捉され、本発明の排ガス処理装置により処理された排ガスが大気中に排出される。
【００５６】
【発明の効果】
本発明の排ガスの処理方法および排ガス処理装置を用いることにより、未燃焼炭素といった粒子状汚染物質を充分に燃焼することにより無毒化して除去することができ、また大気へ放出する排ガス中の窒素酸化物といったガス状汚染物質濃度を減少させることが可能となる。また、本発明の排ガス処理装置は、フィルターが不要であり、装置構成が簡単でコンパクトであり、低コストで製造可能であるため、特に自動車の排気ガス処理装置として有用である。さらに、本発明の排ガス処理装置は、アルカリ水溶液を用いることにより排ガス中の硫黄酸化物や炭化水素などの汚染物質も除去することが可能になる。
【図面の簡単な説明】
【図１】本発明の排ガス処理装置の第１の実施の形態を示した断面図。
【図２】本発明の排ガス処理装置に用いる抵抗加熱板を例示した図。
【図３】本発明の排ガス処理装置に用いる抵抗加熱手段を例示した図。
【図４】本発明の排ガス処理装置の第２の実施の形態を示した断面図。
【図５】本発明の排ガス処理装置の第３の実施の形態を示した断面図。
【図６】本発明の排ガス処理装置の第４の実施の形態を示した断面図。
【図７】図１に示す排ガス処理装置を車両の排気管に接続したところを示した図。
【図８】図５に示す排ガス処理装置を車両の排気管に接続したところを示した図。
【符号の説明】
１…排ガス処理装置
２…フランジ
３、３ａ、３ｂ…中空部材
４…プラズマ発生手段
５…抵抗加熱手段
５ａ…抵抗加熱板
６…充填物
７…中央部電極
８…周部電極
９ａ、９ｂ…導線
１０ａ…中央部軸部材
１０ｂ…端部軸部材
１１ａ、１１ｂ…導線
１２ａ、１２ｂ…多孔板
１３…円筒部材
１４…断熱材
１５…通路
１６…支持部
１７…捕集部材
１８…第１の挿通孔
１９…加熱部
２０…第２の挿通孔
２１…穴
２２…絶縁物
２４…アルカリ水溶液
２５…容器
２６…排気管
２７ａ、２７ｂ…管
２８…空気孔
２９…空気供給手段
３０…排気管
３１…管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas treatment method and an exhaust gas treatment device for a vehicle such as an automobile, a diesel engine, various boilers or garbage incinerators, and more particularly, to a vehicle, a diesel engine, various boilers or a garbage incinerator, and the like. The present invention relates to an exhaust gas treatment method and an exhaust gas treatment device for decomposing or removing gaseous pollutants and particulate pollutants in exhaust gas.
[0002]
[Prior art]
Unburned carbon and dust such as NOx and SOx as gaseous pollutants and soot as particulate pollutants are contained in exhaust gas discharged from vehicles, diesel engines, various boilers or waste incineration facilities. And techniques for decomposing or removing them are provided. Conventionally, in the method of decomposing or removing nitrogen oxides and sulfur oxides, plasma is generated by glow discharge or corona discharge to decompose to nitrogen, sulfur or oxygen, or nitrogen oxides and sulfur using adsorbents. A method of adsorbing and removing oxides has been used. In addition, in the method of removing particulate contaminants such as unburned carbon and dust, a method of separating and removing using a porous ceramic filter or the like, burning using a burner, or collecting and cleaning using a purifying liquid is used. Are used to prevent these pollutants from being released into the atmosphere.
[0003]
Further, in the tunnel, the exhaust gas discharged from the vehicle is accumulated in the tunnel, and the exhaust gas from the vehicle is released into the atmosphere with the ventilation in the tunnel. Considering the recent situation of air pollution and the like, it is necessary to remove nitrogen oxides and suspended particulate contaminants (SPM) as much as possible when discharging the exhaust gas accumulated in the tunnel to the atmosphere.
[0004]
Heretofore, many devices and methods have been proposed as devices capable of removing the above-mentioned nitrogen oxides and particulate contaminants and releasing a clean gas. For example, a method for efficiently decomposing and removing using a heating means and a catalyst or an adsorbent has been proposed.
[0005]
The apparatus disclosed in Japanese Patent Application Laid-Open No. H10-227737 has a structure in which a porous ceramic structure is horizontally set in a plurality of stages, and an electric resistance heating element is installed in a void area of each stage, so that the porous ceramic structure can be placed vertically. The structure allows heating from above. The apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 10-227737 is designed so that secondary air required for combustion can be supplied from outside. This apparatus is characterized in that the temperature difference between the surface and the center of the porous ceramic structure is small, and uniform heating is possible to a combustion temperature at which the effect of temperature uniformization is large. This discloses that the fine particles and undecomposed components trapped in the porous ceramic structure are completely burned and can be discharged as clean exhaust gas to the outside.
[0006]
Further, the apparatus disclosed in Japanese Patent Application Laid-Open No. 11-528 discloses a filter tube comprising an inner filter tube portion, a filter outer tube portion, and an activated carbon layer filled in a space between each of these tube portions. It is an exhaust gas treatment apparatus in which an exhaust gas introduction / exhaust cylinder having a large number of pores is installed in the inner cavity of a filter inner layer cylindrical portion. This exhaust gas treatment device is capable of controlling SO 2 in exhaust gas. ₂ And NO _x Can be subjected to an adsorption treatment using a filter and activated carbon.
[0007]
Furthermore, Japanese Patent Application Laid-Open No. 2001-170483 discloses a combustion catalyst during the treatment of diesel exhaust gas for burning and removing carbon fine particles in diesel exhaust gas. This catalyst is a combustion catalyst for treating diesel exhaust gas comprising catalyst particles made of an alkali metal or an alkaline earth metal and oxidized ceramic particles supporting the catalyst particles. JP-A-2001-170483 discloses that carbon fine particles can be burned with high efficiency even at a relatively low temperature of 500 ° C. or less by using this combustion catalyst.
[0008]
However, in the device disclosed in Japanese Patent Application Laid-Open No. H10-227737, the period of contact with the porous ceramic structure is short, so that it is difficult to sufficiently and efficiently heat and burn, and Sufficient combustion can be achieved by providing many porous ceramic structures and supplying air from a blower, but there is a problem that the apparatus becomes large.
[0009]
Further, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 11-528, the particulate contaminants can be sufficiently adsorbed and removed, and furthermore, the SO contained in the exhaust gas of the diesel engine can be removed. ₂ , NO _x Can be removed efficiently, but it is necessary to replace the filter every predetermined period, and it is necessary to clean the clogged filter, which is troublesome and labor-intensive.
[0010]
Further, in the exhaust gas treatment using the catalyst disclosed in Japanese Patent Application Laid-Open No. 2001-170483, while it is possible to efficiently burn particulate contaminants at a low temperature of 500 ° C. or less, gaseous contaminants, particularly nitrogen oxides Things could not be removed.
[0011]
Sodium carbonate is used in laundry soaps and the like as an auxiliary for enhancing the cleaning action. An aqueous alkaline solution such as an aqueous sodium carbonate solution is widely used to remove sulfurous acid gas generated by combustion of light oil or heavy oil from exhaust gas. Conventionally, a wet desulfurization method has been known as a method for removing sulfurous acid gas using this alkaline aqueous solution. The wet desulfurization method is a method of removing a sulfurous acid gas from an exhaust gas by passing the exhaust gas through an alkaline aqueous solution to react the sulfurous acid gas with an alkali. Further, it is known that the wet desulfurization method can remove sulfurous acid gas in exhaust gas at a high removal rate of 75% or more.
[0012]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above-described problems, and has been made sufficiently harmless to remove particulate contaminants such as unburned carbon in exhaust gas. An object of the present invention is to provide an inexpensive and compact exhaust gas treatment method and an exhaust gas treatment device that can reduce the substance concentration, and that do not use a filter. Further, the exhaust gas treatment method and the exhaust gas treatment apparatus of the present invention can also remove sulfurous acid gas and trace amounts of hydrocarbons in exhaust gas.
[0013]
[Means for Solving the Problems]
That is, the above object of the present invention is achieved by using the exhaust gas treatment method and the exhaust gas treatment apparatus of the present invention.
[0014]
According to the first aspect of the present invention, supplying exhaust gas to the hollow member;
Generating plasma in the exhaust gas by plasma generating means disposed on the hollow member;
On the downstream side of the plasma generating means, a plurality of resistance heating means provided with a passage for the exhaust gas are arranged at predetermined intervals in a direction in which the exhaust gas flows, and ceramics, platinum, and the like are provided between the plurality of resistance heating means. Filling a filler selected from the group consisting of ceramics containing platinum or rhodium,
Heating the filling by the plurality of resistance heating means;
Heating the exhaust gas by contacting the plurality of resistance heating means and the heated filler;
An exhaust gas treatment method comprising:
[0015]
According to the invention of claim 2 of the present invention, the plasma generating means includes a central electrode provided at a central portion of the hollow member, and a peripheral electrode provided inside the hollow member. In addition, there is provided a method for treating an exhaust gas which is glow-discharged from the central electrode toward the peripheral electrode.
[0016]
According to the third aspect of the present invention, there is provided a method for treating exhaust gas, wherein the resistance heating means heats the exhaust gas to 200 ° C to 800 ° C.
[0017]
According to a fourth aspect of the present invention, there is provided a method for treating exhaust gas, comprising the step of passing the exhaust gas through an aqueous alkaline solution.
[0018]
According to the invention of claim 5 of the present invention, the method for treating exhaust gas further supplies air to the upstream side of the resistance heating unit or to both the upstream side and the downstream side of the resistance heating unit. There is provided a method of treating exhaust gas comprising steps.
[0019]
According to the invention of claim 6 of the present invention, there is provided an exhaust gas treatment method for treating nitrogen oxides or particulate pollutants contained in the exhaust gas.
[0020]
According to the invention of claim 7 of the present invention, there is provided a method for treating exhaust gas, wherein the exhaust gas is an exhaust gas from a vehicle, an exhaust gas from a tunnel pit, or an exhaust gas from a waste incineration facility.
[0021]
According to the invention of claim 8 of the present invention, a hollow member to which exhaust gas is supplied,
Plasma generating means disposed inside the hollow member,
A plurality of resistance heating units provided on the downstream side of the plasma generation unit and provided with a passage of the exhaust gas provided at predetermined intervals in a direction in which the exhaust gas flows,
A filler selected from the group consisting of ceramics, platinum, platinum, and rhodium-containing ceramics, which is filled inside the hollow member and adjacent to the plurality of resistance heating means between the plurality of resistance heating means. When,
Wherein the exhaust gas is heated by bringing the exhaust gas into contact with the resistance heating means and the filler heated by the resistance heating means.
[0022]
According to the ninth aspect of the present invention, the plasma generating means includes a central electrode provided at a central portion of the hollow member, and a peripheral electrode provided inside the hollow member. An exhaust gas treatment device is provided.
[0023]
According to the invention of claim 10 of the present invention, there is provided an exhaust gas treatment apparatus in which the central electrode performs glow discharge toward the peripheral electrode.
[0024]
According to the invention of claim 11 of the present invention, there is provided an exhaust gas treatment device further comprising an alkaline aqueous solution and a container containing the alkaline aqueous solution and connected to the hollow member.
[0025]
According to the twelfth aspect of the present invention, there is provided an exhaust gas treatment apparatus wherein the alkaline aqueous solution is a sodium carbonate aqueous solution.
[0026]
According to the invention of claim 13 of the present invention, the exhaust gas treatment apparatus further supplies air to the upstream side of the resistance heating unit or to both the upstream side and the downstream side of the resistance heating unit. An exhaust gas treatment apparatus including the air supply means is provided.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. The exhaust gas treatment apparatus according to the present invention is characterized in that nitrogen contained in exhaust gas from a vehicle such as a gasoline-powered vehicle or a diesel vehicle, or exhaust gas from a tunnel pit, or exhaust gas from a device that burns at a high temperature such as a high-pressure boiler or a garbage incinerator. This is an apparatus that can release oxides and particulate contaminants as clean gases such as carbon dioxide and nitrogen. FIG. 1 is a sectional view showing a first embodiment of the exhaust gas treatment apparatus of the present invention. In the embodiment shown in FIG. 1, an exhaust gas treatment apparatus 1 of the present invention is connected by bolts and nuts (not shown) using a connecting member such as a flange 2, and exhaust gas is supplied from the direction of arrow A. The exhaust gas treatment apparatus 1 shown in FIG. 1 includes a hollow member 3a and a plasma generating means 4 disposed inside the hollow member 3a from the direction of an arrow A to which the exhaust gas is supplied, and a hollow member 3b and an inside of the hollow member 3b. A plurality of resistance heating means 5 provided at predetermined intervals in the direction in which the exhaust gas flows, that is, in the direction of arrow A, and a filler 6 filled between the plurality of resistance heating means 5 are included.
[0028]
The plasma generating means 4 shown in FIG. 1 can generate plasma in exhaust gas, decompose nitrogen oxides contained in the exhaust gas into nitrogen and oxygen, or collect dust by charging dust. The plasma generating means 4 shown in FIG. 1 includes a central electrode 7 disposed at a central portion inside the hollow member 3a, and a peripheral electrode 8 disposed inside the hollow member 3a. The exhaust gas treatment apparatus 1 of the present invention may have a structure in which only one hollow member is used, and the plasma generating means 4 and the resistance heating means 5 are arranged in the same hollow member.
[0029]
Conductive wires 9a and 9b are connected to the central electrode 7 and the peripheral electrode 8 of the plasma generating means 4 shown in FIG. 1, and a voltage is applied from a high-voltage power supply (not shown). In the present invention, a material capable of glow discharge from the central electrode 7 to the peripheral electrode 8 can be used. In the embodiment shown in FIG. 1, when a voltage is applied to the central electrode 7, discharge is performed toward the peripheral electrode 8. In this case, the central electrode 7 functions as a discharge electrode, and the peripheral electrode 8 functions as a ground electrode. The central electrode 7 is provided at the center of the flow path through which the exhaust gas flows, and the peripheral electrode 8 is provided on the entire inner periphery of the hollow member 3a. Discharge from the central electrode 7 generates plasma in a space between the central electrode 7 and the peripheral electrode 8 where the exhaust gas flows, and the exhaust gas flows across the plasma, thereby causing nitrogen oxidation in the exhaust gas. The substance is decomposed into nitrogen and oxygen by the reaction of the following formula (1).
[0030]
Embedded image

[0031]
In the formula (1), N is a nitrogen radical generated by plasma from nitrogen in the exhaust gas, and NO is nitric oxide mainly contained in the exhaust gas. In addition, multi-order NO ₂ Such nitrogen oxides are decomposed into nitric oxide by the above-mentioned nitrogen radicals, and finally decomposed into nitrogen and oxygen by the reaction of the above formula (1). The nitrogen and oxygen are supplied to the downstream resistance heating means 5 together with unburned carbon and the like. Further, dust contained in the exhaust gas can be charged by the plasma generated by the plasma generating means 4, adhered to the peripheral electrode 8 and the like, and removed from the exhaust gas.
[0032]
The center electrode 7 shown in FIG. 1 has a pointed tip facing the exhaust gas supply side, and has a shape that reduces resistance to the flow of exhaust gas. The peripheral electrode 8 is shaped such that a part of the peripheral electrode 8 is close to the central electrode 7. By doing so, it is possible to discharge efficiently from the central electrode 7 to the peripheral electrode 8 and to appropriately generate plasma in the exhaust gas. In addition, since a high-voltage current flows through the peripheral electrode 8, an insulator such as wood or ceramic is provided between the hollow member 3a and the peripheral electrode 8 so that an electric shock does not occur even if the hollow material 3a is touched. can do. The center electrode 7 and the peripheral electrode 8 used for the plasma generating means 4 may be made of any conductive material, for example, iron, copper, silver or the like.
[0033]
The resistance heating means 5 shown in FIG. 1 uses a helical resistance heating plate 5a arranged at a predetermined interval inside the hollow member 3b, and a plurality of helical resistance heating plates 5a are provided in a direction in which the exhaust gas flows. The center of the resistance heating plate 5a is connected to each resistance heating plate 5a, and a central shaft member 10a for supplying a current to each resistance heating plate 5a, and a spiral-shaped resistance heating plate 5a. And an end shaft member 10b for returning a current flowing through the power source to a power source (not shown). Conductive wires 11a and 11b for connecting to a power supply (not shown) are connected to the central shaft member 10a and the end shaft member 10b, so that current can be supplied or returned. In the embodiment shown in FIG. 1, a plurality of resistance heating plates 5a are provided at the center of a center shaft member 10a, and perforated plates 12a and 12b are provided at both ends thereof. The perforated plates 12a and 12b shown in FIG. 1 are provided as stoppers so that the filling material 6 filled between the plurality of resistance heating plates 5a does not flow out.
[0034]
The filler 6 shown in FIG. 1 is filled between the resistance heating plates 5a and between the resistance heating plates 5a and the perforated plates 12a and 12b. The packing 6 shown in FIG. 1 is densely packed so as to be adjacent to the resistance heating plate 5a, so that the heat generated by the resistance heating plate 5a is transmitted to the entire packing 6. Further, a ceramic cylindrical member 13 containing the resistance heating plate 5a and the porous plates 12a, 12b filled with the filler 6 therebetween is disposed inside the hollow member 3b, and the space between the hollow member 3b and the cylindrical member 13 is provided. Is provided with a heat insulating material 14 such as steel wool. The current supplied to the resistance heating plate 5a is appropriately returned to a power source (not shown) through the end shaft member 10b because the outside is the ceramic cylindrical member 13 having an insulating material. The heat generated by the resistance heating plate 5a is transmitted to the filling 6 and the cylindrical member 13. In the present invention, heat radiation is suppressed by the heat insulating material 14 provided on the outer surface side of the cylindrical member 13.
[0035]
The plasma-treated exhaust gas is supplied to the hollow member 3b and supplied to the layer of the packing 6 through the perforated plate 12a. The exhaust gas supplied to the layer of the packing 6 passes through the resistance heating plate 5a and the layer of the packing 6, and is discharged into the atmosphere through the perforated plate 12b. When passing, the exhaust gas is heated by contacting the resistance heating plate 5a and the heated filler 6, and the unburned carbon in the exhaust gas is burned. In the present invention, the fuel is heated to a predetermined temperature and burned by bringing it into sufficient contact through the layer of the packing 6.
[0036]
In FIG. 1, the exhaust gas treatment apparatus 1 of the present invention is connected by a flange 2 so as to be detachable, but any connection means can be supplied to the exhaust gas treatment apparatus 1 of the present invention without exhaust gas leaking outside. However, it can be used. Furthermore, when the connection size with the pipe connected to the exhaust gas treatment device 1 of the present invention is different, the connection can be made using a reducer. Further, the hollow member 3b used in the present invention does not have to be a hollow cylindrical shape as shown in FIG. 1, and may have any shape as long as it is hollow. The material of the hollow member 3b may be any material as long as it can withstand the temperature of the exhaust gas passing therethrough. For example, stainless steel, carbon steel, ceramics, or the like can be used. In order to maintain the internal temperature, a heat insulating material such as slag wool or rock wool can be provided on the outer surface or the inner surface of the hollow member 3b.
[0037]
The resistance heating means 5 shown in FIG. 1 includes a plurality of resistance heating plates 5a having a helical shape as described above, a central shaft member 10a provided to be inserted through the central portion of the resistance heating plate 5a, and a spiral shape from the central portion. In order to return the current flowing through the resistance heating plate 5a to a power source (not shown), an end shaft member 10b inserted through an end of the resistance heating plate 5a, and a lead wire for supplying a current to the resistance heating plate 5a 11a and 11b. The resistance heating plate 5a is formed with a spiral passage 15 for passing exhaust gas, and the resistance heating plate 5a is formed of a material capable of increasing a surface temperature by supplying an electric current, For example, a material having a high electric resistance can be used. In the present invention, a nickel-chromium alloy, a nickel-chromium-iron alloy, or the like can be used. The passage 15 can flow an appropriate amount of exhaust gas, and can have a size that does not allow the filling material 6 filled therein to pass through. Further, the resistance heating plate 5a heats the exhaust gas and also heats the filling material 6 filled therein. Accordingly, for example, unburned carbon remaining in primary combustion means such as an internal combustion engine of an automobile, various boilers, or refuse incineration equipment can be rendered harmless by heating and burning and decomposing nitrogen oxides.
[0038]
In the present invention, the temperature of the exhaust gas can be set to 200 ° C. to 800 ° C. in order to completely burn unburned carbon in the exhaust gas. In the present invention, the temperature of the exhaust gas can be adjusted to 200 ° C to 800 ° C by adjusting the amount of current supplied to the resistance heating plate 5a. When the exhaust gas treatment apparatus 1 of the present invention is connected to a vehicle, a high voltage ignition current from a distributor can be used as a current supplied to the plasma generation means 4, and a current for supplying a current to the resistance heating means 5 can be used. A battery can be used as a power source.
[0039]
In the present invention, the packing 6 is preferably small in order to sufficiently heat the exhaust gas by contacting the exhaust gas. However, in the case of a small filling, the resistance increases, and the above-mentioned primary material on the upstream side of the exhaust gas treatment apparatus 1 of the present invention is used. Load will be applied to the combustion means. Therefore, in consideration of sufficient contact and resistance of the flow of the exhaust gas, it is possible to use the filler 6 having an appropriate size. In the present invention, ceramics with high heat resistance, platinum or ceramics containing platinum can be used as the filler 6. Specific examples include alumina balls having heat resistance and an alumina content of 99% by mass or more, and platinum catalysts using alumina as a carrier. Further, N ₂ A rhodium catalyst supported on alumina or zeolite can be used as a catalyst for decomposing O. Further, a catalyst containing cobalt copper, palladium, vanadium, or the like can be used instead of the above rhodium. In the present invention, it is preferable to use a spherical filler 6 that can be densely packed, and a diameter of 4 mm to 10 mm can be used. Further, in the present invention, it is preferable to densely fill the filler 6 in order to enhance heat transfer. By contacting the resistance heating means 5 and the heated filler 6 of the exhaust gas treatment apparatus 1 of the present invention, a reaction mainly represented by the following formula (2) occurs.
[0040]
Embedded image

[0041]
C is unburned carbon in exhaust gas, and O ₂ Is excess oxygen contained in the exhaust gas. In addition, as described above, the nitrogen oxides in the exhaust gas become superheated steam in the exhaust gas, and are decomposed into nitrogen and oxygen by the action of the superheated steam. Oxygen obtained by decomposition of nitrogen oxide can be used for the reaction of the above formula (2). The carbon dioxide and nitrogen generated by the reaction represented by the above formula (2) and the decomposition reaction of nitrogen oxides are combined with other exhaust gas components such as nitrogen and oxygen plasma-treated on the upstream side and water vapor generated by the primary combustion means. Released inside.
[0042]
Further, the perforated plates 12a and 12b provided so that the filler 6 does not flow out have holes or holes smaller than the diameter of the filler 6 and have any shape as long as the material can withstand the heating temperature. Can also be used. Further, the perforated plates 12a and 12b are disposed so as to face in the direction in which the exhaust gas flows, and the exhaust gas flows through holes provided in the perforated plates 12a and 12b. In the present invention, as the perforated plates 12a and 12b, those made of stainless steel or ceramics can be used. Further, in the present invention, not limited to the perforated plate, any material may be used as long as it can allow exhaust gas to pass therethrough and can prevent the filling 6 filled therein from flowing out.
[0043]
The cylindrical member 13 shown in FIG. 1 is disposed between the outer peripheral portions of the plurality of resistance heating plates 5a and the perforated plates 12a and 12b and the hollow member 3b, and the current supplied to the resistance heating plate 5a appropriately flows. It is provided as follows. In the present invention, when the hollow member 3b is made of an insulating material such as ceramic, the cylindrical member 13 may not be provided. Further, since the cylindrical member 13 is heated by the filling material 6 and the resistance heating plate 5a filled therein, a heat insulating material 14 such as steel wool is provided between the cylindrical member 13 and the hollow member 3b. . In the present invention, any heat insulating material can be used as long as it can block the exhaust gas so as to appropriately flow through the space between the fillers 6 and can insulate without burning even at high temperatures. Further, the perforated plate 12b and the cylindrical member 13 are connected to the support 16 so as to be disposed at predetermined positions inside the hollow member 3b. The support portion 16 is provided at a predetermined position of the hollow member 3b, and includes a plurality of resistance heating plates 5a, perforated plates 12a and 12b, and a central shaft member 10a and an end connecting the same to supply current to each resistance heating plate 5a. The shaft member 10b is fastened to the support 16 together with the cylindrical member 13 by fastening means such as bolts and nuts. In the present invention, an insulator can be provided between the support portion 16 and the perforated plate 12b to prevent current from flowing to the hollow member 3b through the perforated plate 12b connected to the central shaft member 10a.
[0044]
The exhaust gas treatment apparatus 1 shown in FIG. 1 is further provided with a collecting member 17 on the downstream side of the resistance heating means 5 for collecting unburned substances which cannot be burned by the resistance heating means 5 and remain. Can be. The collecting member 17 shown in FIG. 1 may have any mesh size as long as it can collect the remaining unburned substances. Further, as described above, since the exhaust gas is heated to 200 ° C. to 800 ° C. in order to burn unburned carbon as described above, a material that can withstand these temperatures can be used. It can be supported by the support portion 16 provided at a predetermined position inside the hollow member 3b.
[0045]
FIG. 2 is a diagram illustrating a resistance heating plate 5a used in the exhaust gas treatment apparatus 1 of the present invention. The resistance heating plate 5a shown in FIG. 2 is disposed so as to face the direction in which the exhaust gas flows, and the exhaust gas flows through a spiral gap. When passing through the gap between the resistance heating plates 5a, the exhaust gas in contact with the resistance heating plates 5a is heated. In addition, the resistance heating plate 5a heats the filler 6 to be filled adjacently to a predetermined temperature. In the embodiment shown in FIG. 2, a first insertion hole 18 for inserting and connecting the central shaft member 10 a shown in FIG. 1 to a central portion and an end portion of a heating portion 19 having a spiral shape are provided. In addition, a second insertion hole 20 for inserting and connecting the end shaft member 10b shown in FIG. 1 is provided. In the present invention, when a current is applied to the resistance heating plate 5a, it is possible to improve the efficiency of increasing the surface temperature by sufficiently applying an electric resistance. For example, the heating portion 19 has a spiral shape as shown in FIG. be able to. In the present invention, the structure is not limited to the structure shown in FIG. 2 and may be any structure as long as it can sufficiently provide electric resistance.
[0046]
FIG. 3 is a diagram exemplifying the resistance heating means 5 used in the exhaust gas treatment apparatus 1 of the present invention. The resistance heating means 5 shown in FIG. 3 has three resistance heating plates 5a at predetermined intervals and perforated plates 12a and 12b at both ends. Each resistance heating plate 5a and perforated plates 12a and 12b are connected by a center shaft member 10a and an end shaft member 10b. The exhaust gas flows from the perforated plate 12a to the perforated plate 12b through the plurality of resistance heating plates 5a. The current supplied to the resistance heating plate 5a is supplied to each resistance heating plate 5a through the central shaft member 10a. The current supplied to each resistance heating plate 5a flows toward the end of each resistance heating plate 5a through the helically shaped heating unit 19, and to the power source (not shown) through the end shaft member 10b provided at the end. Will be returned. In the embodiment shown in FIG. 3, an insulator can be provided between the central shaft member 10a and the end shaft member 10b and the porous plates 12a, 12b so that no current is supplied to the porous plates 12a, 12b. The filler 6 shown in FIG. 1 is closely packed between the perforated plate 12a and the resistance heating plate 5a, between the resistance heating plates 5a, and between the resistance heating plate 5a and the perforated plate 12b. . The plurality of holes 21 provided in the perforated plates 12a and 12b can be sized so that the filler 6 does not flow out.
[0047]
FIG. 4 is a view showing a second embodiment of the exhaust gas treatment apparatus 1 of the present invention. In the embodiment shown in FIG. 4, the resistance heating means 5 is the same as the apparatus shown in FIG. 1, and the plasma generation means 4 has a different shape. The plasma generating means 4 shown in FIG. 4 has a central electrode 7 elongated in the longitudinal direction of the hollow member 3a, and faces the central electrode 7 on the inner periphery of the hollow member 3a at regular intervals from the central electrode 7. The insulator 22 is provided between the peripheral electrode 8 provided and the peripheral electrode 8 and the hollow member 3a. A voltage is applied to the central electrode 7 shown in FIG. 4 from the conductive wire 9a to generate plasma in the exhaust gas flowing between the central electrode 7 and the peripheral electrode 8. The current flowing to the peripheral electrode 8 through the exhaust gas is returned to a power source (not shown) through the conducting wire 9b. In the present invention, the conducting wire 9b can be connected to a ground or the like. Exhaust gas is subjected to plasma treatment, whereby nitrogen oxides are decomposed into nitrogen and oxygen with the reaction of the above formula (2), and unburned carbon and dust are charged and disposed on the electrode or downstream side. It adheres to the resistance heating means 5 to be performed or is captured by the filling 6. As the central electrode 7 shown in FIG. 4, an electrode that performs corona discharge can be used, but it is preferable to use an electrode that performs glow discharge in order to effectively generate plasma in low-pressure exhaust gas. Further, in the present invention, an electrode to be discharged can be used as the peripheral electrode 8 and an electrode to be installed can be used as the central electrode 7.
[0048]
In the embodiment shown in FIG. 4, the charged unburned carbon and dust contained in the exhaust gas subjected to the plasma treatment adhere to the resistance heating plate 5a and the filler 6 as described above. The resistance heating plate 5a and the filler 6 are heated to a predetermined temperature, and the attached unburned carbon and dust are burned. The uncharged unburned carbon contained in the exhaust gas is heated by coming into contact with the resistance heating plate 5a and the heated filler 6, and burns with the reaction of the above-described formula (1). The exhaust gas subjected to the plasma treatment and the combustion treatment is further released to the atmosphere after particulate contaminants are removed by the trapping member 17.
[0049]
FIG. 5 is a diagram showing a third embodiment of the exhaust gas treatment apparatus 1 of the present invention. The exhaust gas treatment apparatus 1 shown in FIG. 5 further includes a container 25 containing an alkaline aqueous solution 24 in addition to the apparatus shown in FIG. 1 or FIG. In the embodiment shown in FIG. 5, an exhaust pipe 26 taken out of a vehicle or a refuse treatment facility is connected to a pipe 27a taken out of a container 25, and a tip of the pipe 27a is immersed in an alkaline aqueous solution 24. ing. The container 25 has a sealed structure so that the gas inside does not leak to the outside, and has the plasma generating means 4 and the resistance heating means 5 shown in FIG. 1 through a tube 27b connected to the upper part of the container 25. Exhaust gas is supplied to the device. Exhaust gas emitted from vehicles, refuse treatment facilities, etc. includes sulfur oxides (SO _x ), Hydrocarbons, etc. in trace amounts, which also cause air pollution. By passing the exhaust gas through the alkaline aqueous solution 24 shown in FIG. ₂ Nitrogen oxides, sulfur oxides, and hydrocarbons.
[0050]
Examples of the alkaline aqueous solution 24 that can be used in the present invention include an aqueous sodium carbonate solution and an aqueous sodium hydroxide solution. The concentration of sodium carbonate and sodium hydroxide in the aqueous sodium carbonate solution and the aqueous sodium hydroxide solution may be any concentration, but 1 to 10% by mass can be used. For example, when using an aqueous solution of sodium carbonate, unburned carbon can be suspended in the aqueous solution of sodium carbonate; ₂ Reacts with sodium carbonate to form NaNO ₃ And the sulfur oxides react with sodium carbonate to form NaSO ₄ And the hydrocarbons are liquefied with decreasing temperature. However, the NO that is not dissolved in the alkaline aqueous solution 24 and some unburned carbon, together with other components, such as nitrogen, oxygen, carbon dioxide, carbon monoxide, etc., are passed through the pipe 27b to form a hollow member having the plasma generating means 4 shown in FIG. 3a. As described above, the NO in the exhaust gas is decomposed into nitrogen and oxygen by the decomposition reaction according to the formula (1) by the plasma generation means 4, and the particulate contaminants such as unburned carbon are charged. The plasma-treated exhaust gas is heated by the resistance heating means 5 provided in the downstream and the filler 6 heated by the resistance heating means 5 shown in FIG. 1, and unburned carbon and carbon monoxide in the exhaust gas are burned. You. The exhaust gas thus treated is discharged into the atmosphere as a clean exhaust gas mainly containing nitrogen, oxygen, carbon dioxide and water vapor.
[0051]
The container 25 shown in FIG. 5 may have any shape and any size depending on the amount of exhaust gas to be treated. As the material of the container 25, any material can be used as long as it is not corroded by the alkaline aqueous solution 24, and examples thereof include materials such as stainless steel and reinforced plastic. Further, the internal structure of the container 25 is such that the exhaust gas and the alkaline aqueous solution 24 appropriately come into contact with each other, and the unburned carbon, sulfur oxide, NO ₂ And a structure capable of removing hydrocarbons. In the present invention, as shown in FIG. 5, the distal end of the pipe 27a may be arranged toward the bottom of the container 25 so that the exhaust gas rises toward the upper space. Further, as shown in FIG. 5, the bottom of the container 25 may have a structure provided with a groove adapted to the injection of exhaust gas. In the present invention, the structure does not need to have both the plasma generating means and the resistance heating means as shown in FIG. 5, and only the resistance heating means may be used depending on the pollutants in the exhaust gas.
[0052]
FIG. 6 is a diagram showing a fourth embodiment of the exhaust gas treatment apparatus 1 of the present invention. The exhaust gas treatment device 1 shown in FIG. 6 has the same structure as the exhaust gas treatment device shown in FIG. 1, and further includes an air hole 28 for supplying air to the hollow member 3b and an air supply means 29. ing. The plasma-treated exhaust gas contains only 10% by volume to 18% by volume of oxygen, and when there is not enough oxygen, it can be sufficiently heated by the resistance heating plate 5a and the heated filler 6. Will not be burned. The exhaust gas treatment apparatus 1 shown in FIG. 6 can supply oxygen required for combustion by supplying air from the air supply means 29 through the air holes 28. In the present invention, an amount of air required for combustion can be supplied, and more specifically, an appropriate amount of air can be supplied by measuring the oxygen concentration in exhaust gas. As the oxygen concentration, the oxygen concentration in the exhaust gas at a position between the plasma generating means 4 and the resistance heating plate 5a can be measured. Further, in the present invention, not only the structure shown in FIG. 6 but also an air hole 28 is provided on the downstream side of the resistance heating means 5 to supply air to lower the temperature of the exhaust gas and to reduce the pollution in the exhaust gas discharged. The concentration of the substance can also be reduced.
[0053]
The exhaust gas treatment method of the present invention will be described in detail with reference to FIGS. FIG. 7 is a diagram showing a state where the exhaust gas treatment apparatus 1 shown in FIG. 1 is connected to an exhaust pipe 30 of a vehicle having a diesel engine. The exhaust gas treatment apparatus 1 shown in FIG. 7 is connected to an exhaust pipe 30 by a flange 2 or the like, and is supplied with high-temperature exhaust gas emitted from a vehicle. In gasoline vehicles, the concentration of particulate pollutants is low, ₂ It contains a lot of nitrogen oxides such as O, and diesel vehicles contain a lot of particulate pollutants such as unburned carbon. First, before supplying the exhaust gas to the hollow member 3a, a voltage is applied to the central electrode 7 from a power source (not shown). Next, exhaust gas is supplied to the hollow member 3a, and nitrogen oxides in the exhaust gas are decomposed by plasma generated when the exhaust gas passes between the central electrode 7 and the peripheral electrode 8, and unburned carbon or dust is discharged. Such particulate contaminants are charged. Further, a current flows from the central electrode 7 to the peripheral electrode 8 due to the plasma generated in the exhaust gas, and the current is returned to a power supply (not shown). The plasma-treated exhaust gas is supplied toward a hollow member 3b connected to the hollow member 3a, and oxygen generated by the plasma treatment reacts with carbon monoxide and the like in the exhaust gas.
[0054]
In addition, a current is supplied to the resistance heating plate 5a in advance from a power supply (not shown) to heat the resistance heating plate 5a and also heat the filler 6 adjacent to the resistance heating plate 5a to a predetermined temperature. After heating the resistance heating plate 5a and the filling 6 to a predetermined temperature, exhaust gas can be supplied. The exhaust gas subjected to the plasma treatment as described above is supplied to the hollow member 3b, and is fed into the heated filling 6 through the perforated plate 12a. The exhaust gas is heated by flowing through the gap of the filling 6, and unburned components such as unburned carbon are burned. The exhaust gas contacts the filling 6 and the resistance heating plate 5a and flows through the passage 15 provided in the resistance heating plate 5a. Further, the exhaust gas contacts the filling 6 and the resistance heating plate 5a and the gap between the filling 6 and the resistance heating plate. By flowing through the passage 15 of 5a, sufficient heating and combustion of unburned components are performed. In the hollow member 3b, more efficient combustion can be achieved by providing the air holes 28 and the air supply means 29 as shown in FIG. In this case, after heating the filling 6 to a predetermined temperature, air can be supplied from the air supply means 29, and thereafter, exhaust gas can be supplied. Further, the exhaust gas after passing through the resistance heating means 4 is further sufficiently removed by the trapping member 17 to remove the remaining particulate contaminants, and is discharged into the atmosphere.
[0055]
FIG. 8 is a diagram showing a state where the exhaust gas treatment apparatus 1 shown in FIG. 5 is connected to an exhaust pipe of a vehicle. The exhaust gas treatment apparatus 1 shown in FIG. 8 is connected to the exhaust pipe 30 of the vehicle by the flange 2 or the like, and the exhaust gas is supplied into the container 25 through the exhaust pipe 30 and the pipe 31. The tube 31 is disposed toward the bottom of the container 25, and an aqueous alkali solution 24 such as an aqueous sodium carbonate solution is accommodated in the container 25 to a predetermined height. First, as described above, a voltage is applied to the central electrode 7 of the plasma generating means 4, and a current is supplied to the resistance heating plate 5a to heat the filler 6. After heating to a predetermined temperature, the exhaust gas can be supplied to the exhaust gas treatment device 1 of the present invention. The exhaust gas supplied to the alkaline aqueous solution 24 contains unburned carbon and NO in the exhaust gas. ₂ , Sulfur oxides, hydrocarbons and the like are removed by the aqueous alkali solution 24. Exhaust gas that has exited the container 25 can be decomposed and removed by plasma treatment as shown in FIG. 8, which is not removed by the alkaline aqueous solution 24 such as NO. In the plasma treatment, particulate contaminants such as unburned carbon and dust are charged and adhere to the electrodes and the resistance heating plate 5a and the heated filler 6 provided on the downstream side. The particulate contaminants adhering to the electrodes are peeled off by the supply of the exhaust gas, and adhere to the downstream resistance heating plate 5 a and the filler 6. Until the exhaust gas subjected to the plasma treatment contacts the resistance heating plate 5a, oxygen generated by the plasma treatment reacts with unburned substances such as carbon monoxide. Further, the exhaust gas is supplied to the layer of the packing 6 through the perforated plate 12a. The exhaust gas supplied to the layer of the filler 6 flows through the gap while contacting the filler 6, and contacts the resistance heating plate 5a, flows through the passage 15, and is discharged from the perforated plate 12b. During this time, the exhaust gas is sufficiently heated, and unburned substances contained in the exhaust gas are burned. Further, the remaining particulate contaminants are captured by the collection member 17, and the exhaust gas treated by the exhaust gas treatment device of the present invention is discharged into the atmosphere.
[0056]
【The invention's effect】
By using the exhaust gas treatment method and the exhaust gas treatment apparatus of the present invention, particulate contaminants such as unburned carbon can be sufficiently detoxified and removed by sufficiently burning, and nitrogen oxidation in exhaust gas released to the atmosphere can be reduced. It is possible to reduce the concentration of gaseous pollutants such as substances. In addition, the exhaust gas treatment device of the present invention does not require a filter, has a simple structure, is compact, and can be manufactured at low cost, and is therefore particularly useful as an exhaust gas treatment device for automobiles. Furthermore, the exhaust gas treatment apparatus of the present invention can also remove pollutants such as sulfur oxides and hydrocarbons in the exhaust gas by using the alkaline aqueous solution.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of an exhaust gas treatment apparatus according to the present invention.
FIG. 2 is a diagram illustrating a resistance heating plate used in the exhaust gas treatment apparatus of the present invention.
FIG. 3 is a diagram illustrating a resistance heating unit used in the exhaust gas treatment apparatus of the present invention.
FIG. 4 is a sectional view showing a second embodiment of the exhaust gas treatment apparatus of the present invention.
FIG. 5 is a cross-sectional view showing a third embodiment of the exhaust gas treatment apparatus according to the present invention.
FIG. 6 is a sectional view showing a fourth embodiment of the exhaust gas treatment apparatus according to the present invention.
FIG. 7 is a diagram showing a state where the exhaust gas treatment device shown in FIG. 1 is connected to an exhaust pipe of a vehicle.
FIG. 8 is a diagram showing a state where the exhaust gas treatment device shown in FIG. 5 is connected to an exhaust pipe of a vehicle.
[Explanation of symbols]
1. Exhaust gas treatment device
2 ... Flange
3, 3a, 3b ... hollow member
4: Plasma generating means
5. Resistance heating means
5a: Resistance heating plate
6 ... Filling
7 Central electrode
8 ... Peripheral electrode
9a, 9b ... conducting wire
10a: Central shaft member
10b ... end shaft member
11a, 11b ... conductor
12a, 12b ... perforated plate
13 ... Cylindrical member
14 ... Insulation material
15 ... passage
16 ... Support
17 ... Collection member
18 First insertion hole
19 ... Heating section
20: second insertion hole
21 ... hole
22 ... insulator
24 ... Alkaline aqueous solution
25… Container
26 ... exhaust pipe
27a, 27b ... tube
28 ... air hole
29 ... Air supply means
30 ... exhaust pipe
31 ... pipe

Claims (12)

Supplying exhaust gas to the hollow member;
A central electrode disposed at a central portion inside the hollow member; and a plasma generating unit including a peripheral electrode provided inside the hollow member so as to be close to the central electrode. From the discharge toward the peripheral electrode adjacent to , generating a plasma in the exhaust gas passing between the central electrode and the peripheral electrode ,
On the downstream side of the plasma generation means, the exhaust gas is arranged at a predetermined interval in a direction flowing, a plurality of resistors and a passage of the exhaust gas, each of which is formed by the current path and the electrical flow path of the spiral shape by the heating means, the step of heating the ceramic filled between the plurality of resistive heating means, platinum, packing selected from the group consisting of ceramic containing platinum or rhodium,
Heating the exhaust gas by contacting the plurality of resistance heating means and the heated filler;
A method for treating exhaust gas containing. The plasma generation means glow discharge toward the peripheral portion electrode from the central electrode, method of processing an exhaust gas according to claim 1. The exhaust gas treatment method according to claim 1, wherein the resistance heating unit heats the exhaust gas to 200 ° C. to 800 ° C. 4. The method for treating exhaust gas according to claim 1, wherein the method for treating exhaust gas includes passing the exhaust gas through an alkaline aqueous solution. The method of treating the exhaust gas according to claim 1, further comprising supplying air to the upstream side of the resistance heating unit or to both the upstream side and the downstream side of the resistance heating unit. Exhaust gas treatment method. The method for treating exhaust gas according to any one of claims 1 to 5, wherein nitrogen oxides and particulate pollutants contained in the exhaust gas are treated. The exhaust gas treatment method according to any one of claims 1 to 6, wherein the exhaust gas is an exhaust gas from a vehicle, an exhaust gas from a tunnel pit, or an exhaust gas from a waste incineration facility. A hollow member to which exhaust gas is supplied,
A central electrode provided at a central portion inside the hollow member, and a peripheral electrode provided inside the hollow member so as to be close to the central electrode, wherein the central electrode and the peripheral portion are provided. Plasma generation means for generating plasma in the exhaust gas passing between the electrodes ,
A plurality of helical current paths, each of which is provided on the downstream side of the plasma generating means and is provided at a predetermined interval in a direction in which the exhaust gas flows , and each of which includes a spiral current path and the exhaust gas path formed by the current path; Resistance heating means;
A filling material selected from the group consisting of ceramics, platinum, platinum, and rhodium-containing ceramics, which is filled inside the hollow member and adjacent to the plurality of resistance heating means between the plurality of resistance heating means. When,
Wherein the exhaust gas is heated by bringing the exhaust gas into contact with the resistance heating means and the filler heated by the resistance heating means. The exhaust gas treatment device according to claim 8 , wherein the central electrode performs glow discharge toward the peripheral electrode. The exhaust gas treatment apparatus may further comprise an alkaline aqueous solution, containing the alkaline aqueous solution, and a container connected to said hollow member, an exhaust gas processing apparatus according to claim 8 or 9. The exhaust gas treatment device according to claim 10 , wherein the alkaline aqueous solution is a sodium carbonate aqueous solution. The exhaust gas treatment apparatus further comprises an air supply means for both supplying air between the upstream side and the rear flow side of the upstream side or the resistor heating means of the resistance heating means, according to claim 8-11 An exhaust gas treatment device according to any one of the above.

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