JPWO2003068382A1 - Discharge device - Google Patents

Discharge device Download PDF

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JPWO2003068382A1
JPWO2003068382A1 JP2003567560A JP2003567560A JPWO2003068382A1 JP WO2003068382 A1 JPWO2003068382 A1 JP WO2003068382A1 JP 2003567560 A JP2003567560 A JP 2003567560A JP 2003567560 A JP2003567560 A JP 2003567560A JP WO2003068382 A1 JPWO2003068382 A1 JP WO2003068382A1
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discharge
gas
electrode
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inner electrode
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滋 田丸
滋 田丸
秀男 木村
秀男 木村
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Furrex Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/38—Cold-cathode tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/32—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by electrical effects other than those provided for in group B01D61/00
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/818—Employing electrical discharges or the generation of a plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0809—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0826—Details relating to the shape of the electrodes essentially linear
    • B01J2219/083—Details relating to the shape of the electrodes essentially linear cylindrical
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0875—Gas

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  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
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Abstract

一端にガス入口を、他端にガス出口をそれぞれ有する外側電極及び外側電極の内側に配置された内側電極と、内側電極と外側電極との間の空間に被処理ガスを流通させるガス流通手段と、空間に被処理ガスを流通させた状態で内側電極と外側電極との間に放電電圧を印加する電源装置とからなる放電装置であって、空間は、内側電極の外周面の軸線方向における中間部及び前記外側電極の内周面の軸線方向における中間部によって画成されてなる環状の放電発生領域と、放電発生領域より下流側に内側電極の外周面と外側電極の内周面とによって画成される環状空間であって環状空間の内外側電極間の間隙を放電発生領域における内外側電極間の間隙より大きくしてなる放電波及領域とを含み、被処理ガスをガス入口からガス出口に向けて流通させつつ外側電極と内側電極との間に所定の放電電圧を印加すると、放電発生領域における放電が発生し、放電が放電波及領域に波及して持続するように、放電波及領域の間隙を設定してなることを特徴とする放電装置。An outer electrode having a gas inlet at one end and a gas outlet at the other end, an inner electrode disposed inside the outer electrode, and a gas flow means for flowing a gas to be processed into a space between the inner electrode and the outer electrode; A discharge device comprising a power supply device that applies a discharge voltage between the inner electrode and the outer electrode in a state in which the gas to be treated is circulated in the space, the space being an intermediate in the axial direction of the outer peripheral surface of the inner electrode And an annular discharge generating region defined by an intermediate portion in the axial direction of the inner peripheral surface of the outer electrode and the outer electrode, and an outer peripheral surface of the inner electrode and an inner peripheral surface of the outer electrode downstream of the discharge generating region. A discharge spreading region in which the gap between the inner and outer electrodes of the annular space is made larger than the gap between the inner and outer electrodes in the discharge generating region, and the gas to be treated is transferred from the gas inlet to the gas outlet. Flow towards If a predetermined discharge voltage is applied between the outer electrode and the inner electrode while the discharge is applied, a discharge is generated in the discharge generation region, and the gap of the discharge spread region is set so that the discharge spreads and continues in the discharge spread region. A discharge device characterized by comprising:

Description

技術分野
本発明は、放電装置、特に放電の作用で被処理ガスを分解したり、その被処理ガスより化学物質を合成したりする場合等に用いられる放電装置に関する。
背景技術
従来、前記の放電装置における一対の電極は、例えばニードル形状をなし、それら両電極の先端部間にアーク放電を発生させるようになっていた。
しかしながら、従来の放電装置によると、アークが略線状をなすため、そのアークに接触する被処理ガスの単位時間当たりの量が少なく、その結果、合成反応等が生じなかったり、またそれらが生じたとしてもそれらの進行が極めて遅かったりという問題があった。
そこで、本出願人は、先に、内周面を放電面とした筒状外側電極と、外周面を当該放電面に対向する放電面とした筒状内側電極とを備えた放電反応器と、両放電面間の筒形環状通路内に被処理ガスを圧送供給するガス供給手段と、外側電極及び内側電極間に放電電圧を印加する電源装置とを有する放電装置を提案した（特開２００２−３５５５４８号公報参照）。
このように、両放電面間の筒状間隙に被処理ガスを圧送供給しながら筒状外側電極と筒状内側電極との間に放電電圧を印加すると、両放電面の略全体に放電が発生する。これにより、被処理ガスの分解、そのガスを用いた合成等が可能であり、しかもその分解等を効率良く進行させることが可能である。
本出願人は、前記の装置を用いて被処理ガスの分解を行なった結果、被処理ガスに対する処理能力のさらなる向上の必要性を痛感した。
本発明は前記に鑑み、被処理ガスに対する処理能力を一層向上させた放電装置を提供することを目的としている。
発明の開示
上記の目的を達成するために、本発明は、一端にガス入口を、他端にガス出口をそれぞれ有する外側電極及び当該外側電極の内側に配置された内側電極と、前記内側電極と前記外側電極との間の空間に被処理ガスを流通させるガス流通手段と、前記空間に前記被処理ガスを流通させた状態で前記内側電極と前記外側電極との間に放電電圧を印加する電源装置とからなる放電装置であって、前記空間は、前記内側電極の外周面の軸線方向における中間部及び前記外側電極の内周面の軸線方向における中間部によって画成されてなる環状の放電発生領域と、前記放電発生領域より下流側に前記内側電極の外周面と前記外側電極の内周面とによって画成される環状空間であって当該環状空間の前記内外側電極間の間隙を前記放電発生領域における前記内外側電極間の間隙より大きくしてなる放電波及領域とを含み、前記被処理ガスを前記ガス入口から前記ガス出口に向けて流通させつつ前記外側電極と前記内側電極との間に前記所定の放電電圧を印加すると、前記放電発生領域における放電が発生し、当該放電が前記放電波及領域に波及して持続するように、前記放電波及領域の前記間隙を設定してなるのである。
このような構成により、狭い放電発生領域を通過した被処理ガスは、広い放電波及領域において開放されるように流れる。このような被処理ガスの流れに誘起されて、放電発生領域で発生した放電は放電波及領域に波及する。例えば、放電発生領域の放電がアーク放電の場合には、被処理ガスの流れに応じて、一直線状に生じたアーク放電における陽光柱が放電波及領域において円弧状或いは横「Ｕ」字状に延長してアーク放電を持続する。また、前記の構成により、例えば外側電極の内周面の形状を一定に保持しつつ、放電波及領域の体積が放電発生領域の体積よりも大きくなるように、当該放電波及領域の間隙を設定できる。このように体積の大きい放電波及領域が形成されると、被処理ガスが放電に曝される量及び時間がより増大し、よって、被処理ガスに対して本発明の放電装置が有する処理能力を一層向上させることができる。
好ましくは、前記放電波及領域に前記放電発生領域で発生した放電が波及して持続するように、前記外側電極は前記内側電極を同心状に包囲する電極であって、前記内側電極は、前記放電発生領域を形成する円板状部と、前記放電波及領域を形成すべく当該円板状部の前記ガス出口側端に大径端を連ねた円錐台形部とを備えるものとする。そして好ましくは、この円錐台形部の軸線方向の長さを前記円板状部の軸線方向の長さの３倍以上とする。これによって、放電波及領域の内外側電極間の間隙を、放電発生領域からガス出口にかけて徐々に大きくなるように設定できる。これに応じて、所定の放電電圧により形成される電場は、放電発生領域からガス出口にかけて徐々に小さくなる。従って、放電発生領域の放電が、例えば当該電場の急峻な変化等によって放電波及領域へ波及し難くなるといった事態が抑制される。また、放電波及領域の内外側電極間の間隙の広がりに応じて、被処理ガスも、放電発生領域からガス出口にかけて軸線方向に直交する方向に広がるように流れる。このような流れに誘起されて、放電発生領域の放電が放電波及領域に波及し易くなる。
また好ましくは、前記内側電極は、当該内側電極の備える前記円錐台形部の小径端に連なる円柱部を更に備えるものとする。これによって、放電波及領域の内外側電極間の間隙を、円柱部において一定となるように設定できる。これに応じて、所定の放電電圧により形成される電場も、当該円柱部において一定となり、当該円柱部における放電は軸線方向に波及し易くなる。
更にまた好ましくは、前記放電発生領域における、前記内側電極の外周面の軸線方向における中間部と、前記外側電極の内周面の軸線方向における中間部との間の距離を５ｍｍ乃至２５ｍｍとする。これによって、内側電極と外側電極との間に所定の放電電圧を印加すれば、放電発生領域においてアーク放電、グロー放電、又は、グロー放電からアーク放電に至る直前のグロー放電からアーク放電への遷移域の放電を発生させることができる。
また好ましくは、前記放電発生領域の軸線方向の長さを２ｍｍ乃至１０ｍｍとする。このような長さを軸線方向に有する放電発生領域は、被処理ガスに対して、当該被処理ガスが放電波及領域において効率良く開放されるための管路抵抗を与える。即ち、放電発生領域は、放電波及領域とともに、被処理ガスに対して例えばノズルとしての機能を果たすことができる。
発明を実施するための好適な形態
図１に示す放電装置１において、筒形をなす放電反応器２にガス流通手段としてのガス循環装置３が付設される。この装置３は、放電反応器２の一端部に存するガス入口筒４及びその他端部に存するガス出口筒５間を接続する第１導管６を有し、その第１導管６に、ガス出口筒５側より順次、内部中間位置にファン７を配置した透明ボックス８、第１導管６内等の反応経路内の圧力を調節するゴム製圧力調節器９及びガス吸着器１０が装置される。透明ボックス８は合成樹脂、例えばポリメタクリル酸メチルより構成されている。第１導管６に、ガス吸着器１０を迂回するバイパス１１が第１及び第２三方弁１２、１３を介して接続される。また、放電反応器２の外周部に存する両接続端子１４、１５に、電源装置としての交流電源装置１６が導線９７、９８を介して接続される。
ガス循環装置３に被処理ガスを供給すべく、ガス入口筒４及び第１三方弁１２間において第１導管６に、被処理ガス用ガス供給器１７が第２導管１８を介して接続され、その第２導管１８に放電反応器２側より順次、第１開閉弁１９、第３三方弁２０及びフローメータ２１が装置される。第１導管６において、第２導管１８との接続部ａ及び第１三方弁１２間に、その弁１２側へのガス流を阻止する逆止弁２１が装置される。一方、ガス出口筒５側において、第１導管６に第４三方弁２２を介して第３導管２３の入口側が接続され、その出口側は第１導管６の第４三方弁２２下流側に接続される。第３導管２３に、第４三方弁２２側より順次、その弁２２側へのガス流を阻止する逆止弁２４、ガス濃度測定器２５及びその測定器２５側へのガス流を阻止する逆止弁２６が装置される。また、第１導管６において、第３導管２３の出口側との接続部ｂ及び第４三方弁２２間に、その弁２２側へのガス流を阻止する逆止弁２７が装置される。
反応過程にて放電反応器２から排出されたガスの濃度を検出すべく、第１導管６において、第３導管２３の出口側との接続部ｂ及び透明ボックス８間に第４導管２８の入口側が接続され、その出口側はガス濃度測定器２５に接続されている。この場合、濃度測定後のガスの出口側管部としてはガス濃度測定器２５及び第１導管６間に存する第３導管２３の出口側管部２３ａが共用される。第４導管２８において、それの第１導管６との接続部ｃ及びガス濃度測定器２５間に第２開閉弁２９が装置される。
図２、３に示す放電反応器２において、一端にガス入口４５を、他端にガス出口４６をそれぞれ持つ円筒状外側電極４７の両環状端面に、同一の形状を有する電気絶縁性第１、第２端板４８、４９がそれぞれ当てられて、複数のボルト５０によりその外側電極４７に取付けられている。外側電極４７は第１端板４８側に存する大径孔部５１と、第２端板４９側に存する小径孔部５２と、両孔部５１、５２間を繋ぐテーパ孔部５３とを有し、そのテーパ孔部５３と大、小径孔部５１、５２との連接部分は円弧状をなす。大、小径孔部５１、５２及びテーパ孔部５３の内周面は鏡面仕上げ加工を施されている。
外側電極４７内において、第１、第２端板４８、４９間に内側電極５４が保持されて外側電極４７と同心状に配置され、それら内、外側電極４７、５４間には空間Ｓが形成される。その内側電極５４は、その軸線方向中間部に位置する円板状部５５と、それのガス入口４５側端及びガス出口４６側端にそれぞれ大径端を連ねた第１、第２円錐台形部５６、５７と、第１円錐台形部５６の小径端面から突出すると共にそれよりも小径の第１軸部５８と、第２円錐台形部５７の小径端に連なると共にそれと同径の短円柱部５９と、その短円柱部５９の端面から突出すると共にそれよりも小径の第２軸部６０とを有する。それら構成部５５、５６、５７、５８、５９、６０は同軸上に在り、且つそれらの軸線は外側電極４７のそれに合致している。第１軸部５８は第１端板４８に形成された外側電極４７と同軸の貫通孔６１に嵌着し、また第１円錐台形部５６の小径端面が第１端板４８に当接する。外側電極４７内において、第１円錐台形部５６及び円板状部５５は大径孔部５１内に位置し、また第２円錐台形部５７は大径孔部５１、テーパ孔部５３及び小径孔部５２内に渡って位置し、更に短円柱部５９は小径孔部５２内に位置する。第２軸部６０は第２端板４９に形成された外側電極４７と同軸の貫通孔６２に嵌着し、また短円柱部５９の端面が第２端板４９に当接する。円板状部５５、第１、第２円錐台形部５６、５７及び短円柱部５９は鏡面仕上げ加工を施されている。
内、外側電極４７、５４における外、内周面の軸線方向中間部を接近させる、実施例では円板状部５５外周面及び大径孔部５１のテーパ孔部５３近傍内周面を接近させることによって、それら５５、５１間に環状のアーク放電発生領域Ａ１が形成される。またそのアーク放電発生領域Ａ１のガス出口４６側端部に連なり、且つ内、外側電極４７、５４における内、外周両間の間隔をアーク放電発生領域Ａ１よりも拡張して形成された円筒状アーク放電波及領域Ａ２が、実施例では内側電極５４の第２円錐台形部５７及び短円柱部５９と、外側電極４７の大径孔部５１の一部、テーパ孔部５３及び小径孔部５２との協働で形成されている。つまり、空間Ｓにアーク放電発生領域Ａ１とアーク放電波及領域Ａ２が存する。
円板状部５５外周面及び大径孔部５１内周面間の放電距離Ｄｓは、およそ１００ｋＶ以下の交流電圧を内、外側電極５４、４７間に印加する場合には、５ｍｍ≦Ｄｓ≦２５ｍｍとする。実施例では、後述するように７乃至１０ｋＶの交流電圧を内、外側電極５４、４７間に印加するために、Ｄｓ＝５ｍｍに設定した。また、１００ｋＶ以上の交流電圧を内、外側電極５４、４７間に印加する場合には、Ｄｓはおよそ２５０ｍｍ以下が好ましい。
本実施の形態においては、アーク放電波及領域Ａ２は、アーク放電発生領域Ａ１からガス出口筒５にかけて、以下に述べる放電距離を有する。内側電極５４の第２円錐台形部５７の外周面と外側電極４７の大径孔部５１の内周面との間の放電距離は、アーク放電発生領域Ａ１の放電距離（Ｄｓ）に対しておよそ１乃至２倍である。内側電極５４の第２円錐台形部５７の外周面と外側電極４７のテーパ孔部５３の内周面との間の放電距離は、Ｄｓに対しておよそ２乃至３倍である。内側電極５４の第２円錐台形部５７の外周面と外側電極４７の小径孔部５２の内周面との間の放電距離は、Ｄｓに対しておよそ３乃至４倍である。内側電極５４の短円柱部５９の外周面と外側電極４７の小径孔部５２の内周面との間の放電距離は一定で、Ｄｓに対しておよそ４倍である。
また、第２円錐台形部５７の軸線方向の長さは、円板状部５５の軸線方向の長さの３倍以上とする。本実施例では、第２円錐台形部５７の軸線方向の長さは、円板状部５５の軸線方向の長さのおよそ９倍である。更に、円板状部５５の軸線方向の長さは２ｍｍ乃至１０ｍｍとする。本実施例では、円板状部５５の軸線方向の長さはおよそ４ｍｍである。
第１、２端板４８、４９において、貫通孔６１、６２周りに複数の小孔６３、６４が等間隔で形成され（図３参照）、各小孔６３、６４は外側電極４７内に連通する。
第１端板４８の外面側において、その第１端板４８に、ガス入口筒４の一端に存するフランジ部６６が複数のボルト６７により取付けられ、そのガス入口筒４内は第１端板４８の各小孔６３に連通する。また第２端板４９の外面側において、その第２端板４９に、ガス出口筒５の一端に存するフランジ部６９が複数のボルト７０により取付けられ、そのガス出口筒５内は第２端板４９の各小孔６４に連通する。一方の接続端子１４はロッド状をなし、第１端板４８に、それの外周部から相隣る両小孔６３間を通るように形成された細長い孔７３に挿通されて第１軸部５８にねじ止めされており、他方の接続端子１５は外側電極４７の外周部において、その母線の２等分位置にねじ止めされている。図中、７７はシールリングである。
外側電極４７及び内側電極５４はステンレス鋼、例えばＪＩＳ ＳＵＳ３０４より構成されているが、内側電極５４をＡｌ合金、例えばＪＩＳ ５０５２より構成することも可能である。第１、第２端板４８、４９は合成樹脂、例えば布入りベークライトより構成され、またフランジ部６６、６９を有するガス入、ガス出口筒４、５はＡｌ合金、例えばＪＩＳ ５０５２より構成されているが、第１、第２端板４８、４９をセラミックスより構成し、またガス入、ガス出口筒４、５をステンレス鋼より構成することも可能である。ガス吸着器１０は、吸着材としてカサ密度１８０ｇ／ｍ３の活性炭素繊維フィルタ（日本カイノール社製、商品名カイノールＡＣＮ３０５−１５）を有する。このガス吸着器１０における活性炭素繊維フィルタのカサ密度は９０〜１８０ｇ／ｍ３が適当である。
次に、前記放電装置１を、被処理ガスとしての医療用麻酔ガスである笑気（亜酸化窒素Ｎ２Ｏ）の処理に適用した例について説明する。この場合、ガス供給器１７は、笑気及び空気よりなる混合ガスを供給する機能と、笑気のみを供給する機能とを有する。
Ａ．笑気の放電処理及びガスの採取
（ａ）第１開閉弁１９を開き、また第３三方弁２０の切換えによりガス供給器１７と放電反応器２とを連通させた。更に第４三方弁２２の切換えにより放電反応器２のガス出口筒５を透明ボックス８に連通させ、また第１、第２三方弁１２、１３の切換えによりガス吸着器１０の入、出口側を開放すると共にバイパス１１を遮断状態にした。第２開閉弁２９は閉状態にある。
（ｂ）ガス供給器１７から１５ｖｏｌ％の笑気と８５ｖｏｌ％の空気とよりなる混合ガスを放電反応器２に供給し、その混合ガスの供給量が３０Ｌに達したときガス供給器１７からの混合ガスの供給を止め、また第１開閉弁１９を閉じた。
（ｃ）ファン７を送風量１．１ｍ３／ｍｉｎにて作動させ、混合ガスを放電反応器２→第４三方弁２２→逆止弁２７→透明ボックス８→圧力調節器９→第２三方弁１３→ガス吸着器１０→第１三方弁１２→逆止弁２１→放電反応器２の経路で循環させて、内、外側電極４７、５４間の空間Ｓに混合ガスを流通させた。
（ｄ）交流電源装置１６により内、外側電極４７、５４に７〜１０ｋＶ、３０ｍＡ、３３ｋＨｚの高放電電圧を印加した。これにより、内、外側電極４７、５４間の空間Ｓに混合ガスが流通している状態において、内側電極５４の円板状部５５及びそれを囲繞する外側電極４７の大径孔部５１における内周部分間、つまりアーク放電発生領域Ａ１にアーク放電が発生し、そのアークが混合ガスの流れに沿って第２円錐台形部５７及び短円柱部５９周りに波及し、その後アーク放電波及領域Ａ２がアークで満たされた。具体的には、アーク放電発生領域Ａ１において一直線状に生じた陽光柱が、アーク放電波及領域Ａ２において円弧状或いは横「Ｕ」字状に延長し、このような現象が持続した。ところで、前記陽光柱のこのような延長は、狭いアーク放電発生領域Ａ１を通過し広いアーク放電波及領域Ａ２において開放されるように流れる混合ガスに誘起されて生じると考えられる。ここで、第２開閉弁２９を開いて、放電開始後１０分間経過毎に笑気の濃度測定を行った。
表１は笑気の濃度測定結果を示す。
【表１】

Figure 2003068382
表１から明らかなように、放電開始後６０分間という短時間で笑気の全量が分解されたことが判る。なお、ガス吸着器１０においては笑気の分解で生じたＮＯ及びＮＯ２の吸着が行われる。
Ｂ．笑気に対する分解能
［例−Ｉ］
Ｂ−１．笑気の放電処理
（ａ）第１開閉弁１９を開き、また第３三方弁２０の切換えによりガス供給器１７と放電反応器２とを連通させた。更に第４三方弁２２の切換えにより放電反応器２のガス出口筒５をガス濃度測定器２５に連通させ、また第１、第２三方弁１２、１３の切換えによりガス吸着器１０の入、出口側を開放すると共にバイパス１１を遮断状態にした。第２開閉弁２９は閉状態にある。
（ｂ）ガス供給器１７から放電反応器２に１００ｖｏｌ％の笑気を供給し、その笑気濃度がガス濃度測定器２５にて最高測定値に達し、その後供給を続けても測定値が増加しなくなったときガス供給器１７からの笑気の供給を止め、また第１開閉弁１９を閉じた。更に第４三方弁２２の切換えにより放電反応器２のガス出口筒５を、その弁２２及び逆止弁２７を介し透明ボックス８に連通させた。この場合、放電反応器２及びガス循環装置３といった反応経路内のガスは、８１ｖｏｌ％の笑気、３．７ｖｏｌ％の酸素、１３．９ｖｏｌ％の窒素及び残部検出不能ガスよりなる混合ガスであった。これら酸素、窒素及び検出不能ガスは反応経路内における残留ガスである。
（ｃ）ファン７を送風量１．１ｍ３／ｍｉｎにて作動させ、混合ガスを放電反応器２→第４三方弁２２→逆止弁２７→透明ボックス８→圧力調節器９→第２三方弁１３→ガス吸着器１０→第１三方弁１２→逆止弁２１→放電反応器２の経路で循環させて、内、外側電極４７、５４間の空間Ｓに混合ガスを流通させた。
（ｄ）交流電源装置１６により内、外側電極４７、５４に７〜１０ｋＶ、３０ｍＡ、３３ｋＨｚの高放電電圧を印加した。これにより、前記同様に内、外側電極４７、５４間の空間Ｓに混合ガスが流通している状態において、内側電極５４の円板状部５５及びそれを囲繞する外側電極４７の大径孔部５１における内周部分間、つまりアーク放電発生領域Ａ１にアーク放電が発生し、そのアークが混合ガスの流れに沿って第２円錐台形部５７及び短円柱部５９周りに波及し、その後アーク放電波及領域Ａ２がアークで満たされた。具体的には、アーク放電発生領域Ａ１において一直線状に生じた陽光柱が、アーク放電波及領域Ａ２において円弧状或いは横「Ｕ」字状に延長し、このような現象が持続した。ところで、前記陽光柱のこのような延長は、狭いアーク放電発生領域Ａ１を通過し広いアーク放電波及領域Ａ２において開放されるように流れる混合ガスに誘起されて生じると考えられる。
（ｅ）前記放電処理を放電開始後１０分間行い、次いでファン７の作動を停止させると共に交流電源装置１６による内、外側電極４７、５４への高放電電圧の印加を停止し、その後、第１導管６における第１三方弁１２及び逆止弁２１間の位置Ｘで、反応経路内のガスを導管を介してテドラーバックに捕集した。この捕集中に、反応経路内が負圧になるが、反応経路の内圧は圧力調節器９により正圧に調節される。
Ｂ−２．ガス分析
（ａ）捕集ガスについて、ＪＩＳ Ｂ７９５３化学発光法に則りＮＯｘ濃度及びＮＯ濃度をそれぞれ測定し、次いでＮＯｘ濃度−ＮＯ濃度の減算を行ってＮＯ２濃度を求めた。
表２は、捕集ガスのＮＯｘ濃度等を示す。
【表２】
Figure 2003068382
（ｂ）捕集ガスについて、ＣＡＰＮＯＰＭＡＣ ＵＬＴＩＭＡ呼吸器ガス分析装置（デーデックス・オメガ社製）を用いて笑気濃度を測定し、またガスクロマトグラフ（ＧＣ−ＴＣＤ）法に則り酸素濃度及び窒素濃度をそれぞれ測定したところ、表３の結果を得た。
【表３】
Figure 2003068382
表２、３より、前記放電処理によって笑気が１２ｖｏｌ％（１２０，０００ｐｐｍ）分解されて、５，２００ｐｐｍのＮＯ＋ＮＯ２が生じたことから、Ｎ２Ｏ→ＮＯ＋ＮＯ２の分解反応が（５，２００／１２０，０００）×１００＝４．３％発生し、また酸素濃度及び窒素濃度が増加していることから、Ｎ２Ｏ→Ｎ２＋Ｏ２の分解反応が１００％−４．３％＝９５．７％発生した、と考えることができる。なお、ＮＯ２濃度が高い場合には、そのＮＯ２濃度に起因して透明ボックス８内が略赤褐色に変色するが、この測定においては前記現象は見られなかった。
前記のように放電反応器２において、アーク放電波及領域Ａ２を形成すると、その分解能力を向上させて笑気を、主として、単体であり、且つ無害な酸素及び窒素にまで分解することができ、これは分解ガスの処理を容易にする効果をもたらす。
［例−ＩＩ］
表４、５は、図１において、第１、第２三方弁１２、１３の切換えにより第１導管６のバイパス１１を連通状態にすると共にガス吸着器１０の入、出口側を閉じた、ということ以外は例−Ｉと同様の方法で笑気の放電処理を行ったときのガス分析結果を示し、表２、３にそれぞれ対応する。
【表４】
Figure 2003068382
【表５】
Figure 2003068382
表４において、ＮＯｘの値とＮＯ＋ＮＯ２の値とが一致しないのは、ＮＯｘの分解でＮＯ及びＮＯ２以外の化合物が生じていることを考慮したことによる。
この場合には、Ｎ２Ｏ→Ｎ２＋Ｏ２の分解反応が７８％発生し、またＮ２Ｏ→ＮＯ＋ＮＯ２の分解反応が２２％発生した。
例―Ｉと例−ＩＩとを比べると、例―Ｉの方が笑気の分解率が高い。このことから、笑気の分解を高めるためには、分解反応で生じたＮＯ、ＮＯ２をガス吸着器１０により除去した方が良い、と言える。
以上、本発明の好適な実施形態に基づいて説明してきたが、上記した発明の実施の形態は、本発明の理解を容易にするためのものであり、本発明を限定するものではない。
上記した実施の形態における放電装置１は、笑気の分解に限らず、例えば空中窒素を用いたＮＯ２の合成、ＮＯｘの分解、ＣＯ２の分解等に適用可能である。例えば、ＮＯ２を効率良く合成するためには、前述と同様に、放電発生領域Ａ１及び放電波及領域Ａ２における放電はアーク放電がよい。一方、例えば、ＮＯｘ中のＮＯ２の生成を抑制しつつＮＯを効率良く分解するためには、放電発生領域Ａ１及び放電波及領域Ａ２における放電は、グロー放電からアーク放電に至る直前のグロー放電からアーク放電への遷移域の放電がよい。
また、上記した実施の形態における外側電極４７は、第１端板４８側に存する大径孔部５１と、第２端板４９側に存する小径孔部５２と、両孔部５１、５２間を繋ぐテーパ孔部５３とを有しているが、これに限定されるものではない。例えば、図４に示されるように、外側電極４７’の貫通孔は大径孔部５１’の内径と同一の内径を有する等径孔でもよい。この場合、図４に示される放電領域Ａ２における内側電極５４の外周面と外側電極４７の内周面との間隙が、図２に示される間隙に対してできるだけ変化しないように、図４に示される第２円錐台形部５７’の軸線方向の長さは、円板状部５５の軸線方向の長さのおよそ１５倍としてある。ここで、図４においては、図２における構成と同一の構成については同一の符号を付してある。
産業上の利用可能性
本発明によれば、前記のような構成をすることによって、笑気の分解、空中窒素を用いたＮＯ２の合成、ＮＯｘの分解、ＣＯ２の分解等を効率良く実施することが可能な放電装置を提供することができる。
【図面の簡単な説明】
第１図は本発明の実施例に係る放電反応器を用いて笑気ガスの分解実験を行なった放電装置の系統図である。
第２図は本発明の実施例に係る放電反応器の要部破断正面図である。
第３図は図２の３−３断面図である。
第４図は本発明のもう一つの実施例に係る放電反応器の要部破断正面図である。Technical field
The present invention relates to a discharge device, and more particularly to a discharge device used when a gas to be processed is decomposed by the action of discharge or a chemical substance is synthesized from the gas to be processed.
Background art
Conventionally, the pair of electrodes in the above-described discharge device has a needle shape, for example, and generates an arc discharge between the tip portions of both electrodes.
However, according to the conventional discharge device, since the arc is substantially linear, the amount of the gas to be treated that contacts the arc is small per unit time, and as a result, the synthesis reaction or the like does not occur or occurs. Even so, there was a problem that their progress was extremely slow.
Therefore, the present applicant, first, a discharge reactor comprising a cylindrical outer electrode whose inner peripheral surface is a discharge surface, and a cylindrical inner electrode whose outer peripheral surface is a discharge surface facing the discharge surface; There has been proposed a discharge device having a gas supply means for supplying a gas to be processed into a cylindrical annular passage between both discharge surfaces, and a power supply device for applying a discharge voltage between the outer electrode and the inner electrode (Japanese Patent Laid-Open No. 2002-2002). 355548).
In this way, when a discharge voltage is applied between the cylindrical outer electrode and the cylindrical inner electrode while supplying the gas to be processed to the cylindrical gap between the two discharge surfaces, a discharge is generated on substantially the entire discharge surface. To do. As a result, the gas to be treated can be decomposed, synthesized using the gas, and the like, and the decomposition can proceed efficiently.
As a result of performing the decomposition of the gas to be processed using the above-described apparatus, the present applicant became keenly aware of the necessity for further improvement of the processing capability for the gas to be processed.
In view of the above, an object of the present invention is to provide a discharge device that further improves the processing capability for a gas to be processed.
Disclosure of the invention
In order to achieve the above object, the present invention provides an outer electrode having a gas inlet at one end and a gas outlet at the other end, an inner electrode disposed inside the outer electrode, the inner electrode, and the outer electrode. A gas distribution means for circulating a gas to be processed in a space between the power source and a power supply device for applying a discharge voltage between the inner electrode and the outer electrode in a state where the gas to be processed is circulated in the space An annular discharge generation region defined by an intermediate portion in the axial direction of the outer peripheral surface of the inner electrode and an intermediate portion in the axial direction of the inner peripheral surface of the outer electrode; An annular space defined by an outer peripheral surface of the inner electrode and an inner peripheral surface of the outer electrode on the downstream side of the discharge generating region, and a gap between the inner and outer electrodes of the annular space is defined in the discharge generating region. Previous A discharge spreading region that is larger than the gap between the inner and outer electrodes, and the predetermined gas is passed between the outer electrode and the inner electrode while flowing the gas to be processed from the gas inlet toward the gas outlet. When a discharge voltage is applied, a discharge is generated in the discharge generation region, and the gap in the discharge spill region is set so that the discharge spills over and continues in the discharge spill region.
With such a configuration, the gas to be processed that has passed through the narrow discharge generating region flows so as to be released in a wide discharge spreading region. The discharge generated in the discharge generation region by being induced by the flow of the gas to be processed spreads to the discharge spillover region. For example, when the discharge in the discharge generation region is an arc discharge, the positive column in the arc discharge generated in a straight line extends in an arc shape or a horizontal “U” shape in the discharge spread region according to the flow of the gas to be processed. The arc discharge is continued. In addition, with the above-described configuration, for example, the gap of the discharge spreading region can be set so that the volume of the discharge spreading region is larger than the volume of the discharge generating region while keeping the shape of the inner peripheral surface of the outer electrode constant. . When a discharge spreading region having a large volume is formed in this way, the amount and time for which the gas to be processed is exposed to the discharge are further increased. Therefore, the processing capability of the discharge device of the present invention for the gas to be processed is increased. This can be further improved.
Preferably, the outer electrode is an electrode that concentrically surrounds the inner electrode so that the discharge generated in the discharge generation region spreads to the discharge spreading region, and the inner electrode includes the discharge A disk-shaped part that forms the generation region and a frustoconical part that has a large-diameter end connected to the gas outlet side end of the disk-shaped part to form the discharge spreading region are provided. Preferably, the length of the truncated cone portion in the axial direction is at least three times the length of the disk-shaped portion in the axial direction. Thus, the gap between the inner and outer electrodes in the discharge spreading region can be set to gradually increase from the discharge generation region to the gas outlet. Accordingly, the electric field formed by the predetermined discharge voltage gradually decreases from the discharge generation region to the gas outlet. Accordingly, it is possible to suppress a situation in which the discharge in the discharge generation region becomes difficult to spread to the discharge spreading region due to, for example, a sharp change in the electric field. Further, the gas to be processed also flows so as to spread in a direction orthogonal to the axial direction from the discharge generation region to the gas outlet in accordance with the spread of the gap between the inner and outer electrodes in the discharge spreading region. Induced by such a flow, the discharge in the discharge generation region easily spreads to the discharge spreading region.
Further preferably, the inner electrode further includes a columnar portion connected to a small diameter end of the frustoconical portion included in the inner electrode. Thereby, the gap between the inner and outer electrodes in the discharge spreading region can be set to be constant in the cylindrical portion. Accordingly, the electric field formed by the predetermined discharge voltage is also constant in the cylindrical portion, and the discharge in the cylindrical portion is easily propagated in the axial direction.
More preferably, the distance between the intermediate portion in the axial direction of the outer peripheral surface of the inner electrode and the intermediate portion in the axial direction of the inner peripheral surface of the outer electrode in the discharge generation region is 5 mm to 25 mm. As a result, if a predetermined discharge voltage is applied between the inner electrode and the outer electrode, transition from arc discharge, glow discharge, or glow discharge immediately before glow discharge to arc discharge occurs in the discharge generation region. A discharge of the region can be generated.
Preferably, the length of the discharge generation region in the axial direction is 2 mm to 10 mm. The discharge generation region having such a length in the axial direction gives the tube gas resistance for efficiently releasing the gas to be processed in the discharge spreading region. In other words, the discharge generation region can function as a nozzle for the gas to be processed together with the discharge spreading region.
Preferred embodiments for carrying out the invention
In a discharge device 1 shown in FIG. 1, a gas circulation device 3 as a gas circulation means is attached to a discharge reactor 2 having a cylindrical shape. This apparatus 3 has a first conduit 6 that connects between a gas inlet tube 4 at one end of the discharge reactor 2 and a gas outlet tube 5 at the other end. In order from the 5th side, a transparent box 8 in which a fan 7 is arranged at an internal intermediate position, a rubber pressure regulator 9 for adjusting the pressure in the reaction path such as in the first conduit 6 and a gas adsorber 10 are installed. The transparent box 8 is made of a synthetic resin such as polymethyl methacrylate. A bypass 11 that bypasses the gas adsorber 10 is connected to the first conduit 6 via first and second three-way valves 12 and 13. In addition, an AC power supply device 16 as a power supply device is connected to both connection terminals 14 and 15 existing on the outer peripheral portion of the discharge reactor 2 through lead wires 97 and 98.
In order to supply the gas to be processed to the gas circulation device 3, a gas supply unit 17 for the gas to be processed is connected to the first conduit 6 between the gas inlet cylinder 4 and the first three-way valve 12 via the second conduit 18. A first opening / closing valve 19, a third three-way valve 20, and a flow meter 21 are sequentially installed in the second conduit 18 from the discharge reactor 2 side. In the 1st conduit | pipe 6, the non-return valve 21 which blocks | prevents the gas flow to the valve 12 side is provided between the connection part a with the 2nd conduit | pipe 18, and the 1st three-way valve 12. FIG. On the other hand, on the gas outlet cylinder 5 side, the inlet side of the third conduit 23 is connected to the first conduit 6 via the fourth three-way valve 22, and the outlet side is connected to the downstream side of the fourth three-way valve 22 of the first conduit 6. Is done. In the third conduit 23, the check valve 24 for blocking the gas flow to the valve 22 side, the gas concentration measuring device 25 and the reverse for blocking the gas flow to the measuring device 25 side sequentially from the fourth three-way valve 22 side. A stop valve 26 is provided. Further, in the first conduit 6, a check valve 27 is provided between the connection portion b of the third conduit 23 with the outlet side and the fourth three-way valve 22 to prevent gas flow to the valve 22 side.
In order to detect the concentration of the gas discharged from the discharge reactor 2 in the course of the reaction, the inlet of the fourth conduit 28 in the first conduit 6 is connected between the connection b of the outlet of the third conduit 23 and the transparent box 8. The outlet side is connected to the gas concentration measuring device 25. In this case, the outlet side pipe portion 23 a of the third conduit 23 existing between the gas concentration measuring device 25 and the first conduit 6 is shared as the outlet side pipe portion of the gas after concentration measurement. In the fourth conduit 28, a second on-off valve 29 is provided between the connection portion c of the fourth conduit 28 and the gas concentration measuring device 25.
In the discharge reactor 2 shown in FIGS. 2 and 3, the first and second electrically insulating first and second cylindrical end electrodes 47 each having a gas inlet 45 at one end and a gas outlet 46 at the other end have the same shape. Second end plates 48 and 49 are respectively applied and attached to the outer electrode 47 by a plurality of bolts 50. The outer electrode 47 has a large-diameter hole portion 51 existing on the first end plate 48 side, a small-diameter hole portion 52 existing on the second end plate 49 side, and a tapered hole portion 53 connecting both the hole portions 51 and 52. The connecting portion between the tapered hole portion 53 and the large and small diameter hole portions 51 and 52 has an arc shape. The inner peripheral surfaces of the large and small diameter hole portions 51 and 52 and the tapered hole portion 53 are mirror finished.
In the outer electrode 47, the inner electrode 54 is held between the first and second end plates 48 and 49 and is arranged concentrically with the outer electrode 47, and a space S is formed between the outer electrodes 47 and 54. Is done. The inner electrode 54 includes a disk-shaped portion 55 located in the middle in the axial direction, and first and second frustoconical portions each having a large diameter end connected to a gas inlet 45 side end and a gas outlet 46 side end thereof. 56, 57, a first cylindrical portion 58 projecting from the small-diameter end surface of the first truncated cone portion 56 and having a smaller diameter than that, and a short cylindrical portion 59 connected to the small-diameter end of the second truncated cone portion 57 and having the same diameter And a second shaft portion 60 that protrudes from the end surface of the short cylindrical portion 59 and has a smaller diameter than that. These components 55, 56, 57, 58, 59, 60 are coaxial and their axes coincide with those of the outer electrode 47. The first shaft portion 58 is fitted into a through hole 61 coaxial with the outer electrode 47 formed on the first end plate 48, and the small-diameter end surface of the first frustoconical portion 56 contacts the first end plate 48. In the outer electrode 47, the first truncated cone part 56 and the disk-like part 55 are located in the large diameter hole part 51, and the second truncated cone part 57 is the large diameter hole part 51, the tapered hole part 53, and the small diameter hole. The short cylindrical part 59 is located in the small diameter hole part 52 and is located over the part 52. The second shaft portion 60 is fitted into a through-hole 62 coaxial with the outer electrode 47 formed on the second end plate 49, and the end surface of the short cylindrical portion 59 is in contact with the second end plate 49. The disk-shaped part 55, the first and second frustoconical parts 56 and 57, and the short cylindrical part 59 are mirror finished.
In the embodiment, the outer peripheral surfaces of the inner and outer electrodes 47 and 54 are made closer to the axially intermediate portion of the inner peripheral surface. Thus, an annular arc discharge generation region A between the 55 and 51 is obtained. 1 Is formed. Also, arc discharge generation area A 1 The distance between the inner and outer electrodes of the inner and outer electrodes 47 and 54 is defined as the arc discharge generation region A. 1 Cylindrical arc discharge spreading area A formed by expanding 2 In the embodiment, however, the second frustoconical portion 57 and the short cylindrical portion 59 of the inner electrode 54 and a part of the large-diameter hole portion 51, the tapered hole portion 53 and the small-diameter hole portion 52 of the outer electrode 47 are formed in cooperation. Has been. That is, the arc discharge occurrence area A in the space S 1 And arc discharge spread area A 2 Exist.
The discharge distance Ds between the outer peripheral surface of the disk-shaped portion 55 and the inner peripheral surface of the large-diameter hole portion 51 is 5 mm ≦ Ds ≦ 25 mm when an AC voltage of about 100 kV or less is applied between the inner electrodes 54 and 47. And In the example, in order to apply an AC voltage of 7 to 10 kV between the inner and outer electrodes 54 and 47 as described later, Ds = 5 mm was set. In addition, when an AC voltage of 100 kV or higher is applied between the inner and outer electrodes 54 and 47, Ds is preferably about 250 mm or less.
In the present embodiment, arc discharge spreading area A 2 Is the arc discharge occurrence area A 1 To the gas outlet tube 5 has a discharge distance described below. The discharge distance between the outer peripheral surface of the second frustoconical portion 57 of the inner electrode 54 and the inner peripheral surface of the large-diameter hole portion 51 of the outer electrode 47 is determined by the arc discharge generation region A. 1 The discharge distance (Ds) is approximately 1 to 2 times. The discharge distance between the outer peripheral surface of the second frustoconical portion 57 of the inner electrode 54 and the inner peripheral surface of the tapered hole portion 53 of the outer electrode 47 is approximately 2 to 3 times the Ds. The discharge distance between the outer peripheral surface of the second frustoconical portion 57 of the inner electrode 54 and the inner peripheral surface of the small diameter hole portion 52 of the outer electrode 47 is approximately 3 to 4 times Ds. The discharge distance between the outer peripheral surface of the short cylindrical portion 59 of the inner electrode 54 and the inner peripheral surface of the small-diameter hole portion 52 of the outer electrode 47 is constant and is approximately four times as large as Ds.
Further, the length of the second frustoconical portion 57 in the axial direction is at least three times the length of the disc-shaped portion 55 in the axial direction. In the present embodiment, the length of the second frustoconical portion 57 in the axial direction is approximately nine times the length of the disc-shaped portion 55 in the axial direction. Further, the length of the disc-shaped portion 55 in the axial direction is 2 mm to 10 mm. In the present embodiment, the length of the disk-shaped portion 55 in the axial direction is approximately 4 mm.
In the first and second end plates 48, 49, a plurality of small holes 63, 64 are formed at equal intervals around the through holes 61, 62 (see FIG. 3), and the small holes 63, 64 communicate with the outer electrode 47. To do.
On the outer surface side of the first end plate 48, a flange portion 66 existing at one end of the gas inlet tube 4 is attached to the first end plate 48 by a plurality of bolts 67, and the inside of the gas inlet tube 4 is inside the first end plate 48. The small holes 63 communicate with each other. Further, on the outer surface side of the second end plate 49, a flange portion 69 existing at one end of the gas outlet tube 5 is attached to the second end plate 49 by a plurality of bolts 70, and the inside of the gas outlet tube 5 is the second end plate. It communicates with 49 small holes 64. One connection terminal 14 has a rod shape, and is inserted into the first end plate 48 through an elongated hole 73 formed so as to pass between the small holes 63 adjacent to each other from the outer peripheral portion of the first end plate 48. The other connection terminal 15 is screwed at the outer peripheral portion of the outer electrode 47 at the bisected position of the bus bar. In the figure, reference numeral 77 denotes a seal ring.
The outer electrode 47 and the inner electrode 54 are made of stainless steel, for example, JIS SUS304. However, the inner electrode 54 can be made of an Al alloy, for example, JIS 5052. The first and second end plates 48 and 49 are made of a synthetic resin, for example, a bakelite with cloth, and the gas inlet and the gas outlet cylinders 4 and 5 having flange portions 66 and 69 are made of an Al alloy, for example, JIS 5052. However, the first and second end plates 48 and 49 can be made of ceramics, and the gas inlet and gas outlet tubes 4 and 5 can be made of stainless steel. The gas adsorber 10 has a bulk density of 180 g / m as an adsorbent. 3 Activated carbon fiber filter (trade name Kynol ACN305-15, manufactured by Nippon Kynol Co., Ltd.). The bulk density of the activated carbon fiber filter in the gas adsorber 10 is 90 to 180 g / m. 3 Is appropriate.
Next, the discharge device 1 is connected to laughing gas (nitrous oxide N) which is a medical anesthetic gas as a gas to be processed 2 An example applied to the process O) will be described. In this case, the gas supplier 17 has a function of supplying a mixed gas composed of laughter and air and a function of supplying only laughter.
A. Discharge treatment of laughter and gas sampling
(A) The first on-off valve 19 was opened, and the gas supply unit 17 and the discharge reactor 2 were connected by switching the third three-way valve 20. Further, the gas outlet tube 5 of the discharge reactor 2 is communicated with the transparent box 8 by switching the fourth three-way valve 22, and the inlet and outlet sides of the gas adsorber 10 are switched by switching the first and second three-way valves 12, 13. While opening, the bypass 11 was cut off. The second on-off valve 29 is in a closed state.
(B) A gas mixture consisting of 15 vol% laughing gas and 85 vol% air is supplied from the gas supply unit 17 to the discharge reactor 2, and when the supply amount of the mixed gas reaches 30 L, the gas supply unit 17 The supply of the mixed gas was stopped, and the first on-off valve 19 was closed.
(C) The fan 7 has an air flow of 1.1 m. 3 The gas mixture is discharged at the discharge reactor 2 → the fourth three-way valve 22 → the check valve 27 → the transparent box 8 → the pressure regulator 9 → the second three-way valve 13 → the gas adsorber 10 → the first three-way valve. The mixed gas was circulated in the space S between the inner and outer electrodes 47 and 54 by circulating through the path of 12 → check valve 21 → discharge reactor 2.
(D) A high discharge voltage of 7 to 10 kV, 30 mA, 33 kHz was applied to the inner and outer electrodes 47 and 54 by the AC power supply device 16. As a result, in a state where the mixed gas is flowing in the space S between the inner and outer electrodes 47 and 54, the inner portion of the disk-shaped portion 55 of the inner electrode 54 and the large-diameter hole portion 51 of the outer electrode 47 surrounding it. Around the circumference, that is, arc discharge generation area A 1 An arc discharge is generated in the arc, and the arc spreads around the second frustoconical portion 57 and the short cylindrical portion 59 along the flow of the mixed gas, and then the arc discharge spreading area A 2 Filled with arc. Specifically, arc discharge generation area A 1 The positive column generated in a straight line in FIG. 2 In this case, the phenomenon was extended to an arc shape or a horizontal “U” shape, and such a phenomenon persisted. By the way, such an extension of the positive column has a narrow arc discharge generation area A. 1 Wide arc discharge spreading area A passing through 2 It is thought that it is induced by a mixed gas flowing so as to be released in Here, the second on-off valve 29 was opened, and the concentration of laughter was measured every 10 minutes after the start of discharge.
Table 1 shows the concentration measurement results of laughter.
[Table 1]
Figure 2003068382
As is apparent from Table 1, it can be seen that the entire amount of laughter was decomposed in a short period of 60 minutes after the start of discharge. In the gas adsorber 10, NO and NO generated by the decomposition of laughing gas 2 Is adsorbed.
B. Resolution for laughter
[Example-I]
B-1. Laughing discharge treatment
(A) The first on-off valve 19 was opened, and the gas supply unit 17 and the discharge reactor 2 were connected by switching the third three-way valve 20. Further, the gas outlet cylinder 5 of the discharge reactor 2 is communicated with the gas concentration measuring device 25 by switching the fourth three-way valve 22, and the gas adsorber 10 is turned on and off by switching the first and second three-way valves 12, 13. The side was opened and the bypass 11 was shut off. The second on-off valve 29 is in a closed state.
(B) 100 vol% of laughing gas is supplied from the gas supply device 17 to the discharge reactor 2, and the laughing gas concentration reaches the maximum measured value in the gas concentration measuring device 25, and the measured value increases even if the supply is continued thereafter. When it stopped, the supply of laughing gas from the gas supply device 17 was stopped, and the first on-off valve 19 was closed. Further, by switching the fourth three-way valve 22, the gas outlet cylinder 5 of the discharge reactor 2 was communicated with the transparent box 8 via the valve 22 and the check valve 27. In this case, the gas in the reaction path such as the discharge reactor 2 and the gas circulation device 3 is a mixed gas composed of 81 vol% laughing gas, 3.7 vol% oxygen, 13.9 vol% nitrogen, and the remainder undetectable gas. It was. These oxygen, nitrogen and undetectable gases are residual gases in the reaction path.
(C) The fan 7 has an air flow of 1.1 m. 3 The gas mixture is discharged at the discharge reactor 2 → the fourth three-way valve 22 → the check valve 27 → the transparent box 8 → the pressure regulator 9 → the second three-way valve 13 → the gas adsorber 10 → the first three-way valve. The mixed gas was circulated in the space S between the inner and outer electrodes 47 and 54 by circulating through the path of 12 → check valve 21 → discharge reactor 2.
(D) A high discharge voltage of 7 to 10 kV, 30 mA, 33 kHz was applied to the inner and outer electrodes 47 and 54 by the AC power supply device 16. Accordingly, in the same manner as described above, in the state where the mixed gas is flowing in the space S between the inner and outer electrodes 47 and 54, the disk-shaped portion 55 of the inner electrode 54 and the large-diameter hole portion of the outer electrode 47 surrounding it. 51, the inner circumference portion, that is, the arc discharge generation area A 1 Arc discharge is generated in the gas, and the arc spreads around the second frustoconical portion 57 and the short cylindrical portion 59 along the flow of the mixed gas, and then the arc discharge ripple area A 2 Filled with arc. Specifically, arc discharge generation area A 1 The positive column generated in a straight line in FIG. 2 In this case, the phenomenon was extended to an arc shape or a horizontal “U” shape, and such a phenomenon persisted. By the way, such an extension of the positive column has a narrow arc discharge generation area A. 1 Wide arc discharge spreading area A passing through 2 It is thought that it is induced by a mixed gas flowing so as to be released in
(E) The discharge treatment is performed for 10 minutes after the start of discharge, and then the operation of the fan 7 is stopped and the application of the high discharge voltage to the outer electrodes 47 and 54 by the AC power supply device 16 is stopped. At the position X between the first three-way valve 12 and the check valve 21 in the conduit 6, the gas in the reaction path was collected in the Tedlar bag via the conduit. This trapping concentration results in a negative pressure in the reaction path, but the internal pressure in the reaction path is adjusted to a positive pressure by the pressure regulator 9.
B-2. Gas analysis
(A) For the collected gas, the NOx concentration and the NO concentration are measured according to the JIS B7953 chemiluminescence method, and then the NOx concentration minus the NO concentration is subtracted. 2 The concentration was determined.
Table 2 shows the NOx concentration and the like of the collected gas.
[Table 2]
Figure 2003068382
(B) For the collected gas, measure the laughing gas concentration using a CAPNOPMAC ULTIMA respiratory gas analyzer (manufactured by Dedex Omega), and determine the oxygen concentration and nitrogen concentration according to the gas chromatograph (GC-TCD) method. When measured, the results shown in Table 3 were obtained.
[Table 3]
Figure 2003068382
From Tables 2 and 3, laughing gas was decomposed by 12 vol% (120,000 ppm) by the discharge treatment, and 5,200 ppm of NO + NO 2 N 2 O → NO + NO 2 Since the decomposition reaction of (5,200 / 120,000) × 100 = 4.3% occurs and the oxygen concentration and nitrogen concentration increase, N 2 O → N 2 + O 2 It can be considered that the decomposition reaction of 100% -4.3% = 95.7% occurred. NO 2 If the concentration is high, the NO 2 Due to the density, the inside of the transparent box 8 changes to substantially reddish brown, but this phenomenon was not observed in this measurement.
In the discharge reactor 2 as described above, the arc discharge spreading area A 2 Can improve the decomposition ability and can decompose laughing gas into mainly simple and harmless oxygen and nitrogen, which has the effect of facilitating the treatment of the cracked gas.
[Example-II]
Tables 4 and 5 show that in FIG. 1, the bypass 11 of the first conduit 6 is brought into a communication state by switching the first and second three-way valves 12 and 13, and the inlet and outlet sides of the gas adsorber 10 are closed. Except for this, the results of gas analysis when laughing gas was discharged in the same manner as in Example-I are shown and correspond to Tables 2 and 3, respectively.
[Table 4]
Figure 2003068382
[Table 5]
Figure 2003068382
In Table 4, the value of NOx and NO + NO 2 The values of NO and NO are not consistent with the decomposition of NOx. 2 This is due to the fact that other compounds are generated.
In this case, N 2 O → N 2 + O 2 Decomposition reaction of 78% occurs, and N 2 O → NO + NO 2 The decomposition reaction of 22% occurred.
Comparing Example-I and Example-II, Example-I has a higher decomposition rate of laughter. From this, in order to enhance the decomposition of laughter, NO, NO generated by the decomposition reaction 2 It can be said that the gas should be removed by the gas adsorber 10.
As mentioned above, although demonstrated based on preferred embodiment of this invention, embodiment mentioned above is for making an understanding of this invention easy, and does not limit this invention.
The discharge device 1 in the above-described embodiment is not limited to the decomposition of laughter, for example, NO using air nitrogen 2 Synthesis, NOx decomposition, CO 2 It can be applied to the decomposition of For example, NO 2 In order to efficiently synthesize the discharge generation area A as described above. 1 And discharge spreading area A 2 The arc discharge is preferably arc discharge. On the other hand, for example, NO in NOx 2 In order to efficiently decompose NO while suppressing the generation of NO, the discharge generation region A 1 And discharge spreading area A 2 The discharge in is preferably a discharge in the transition region from the glow discharge to the arc discharge immediately before the glow discharge to the arc discharge.
Further, the outer electrode 47 in the above-described embodiment includes a large-diameter hole portion 51 existing on the first end plate 48 side, a small-diameter hole portion 52 existing on the second end plate 49 side, and a space between both the hole portions 51 and 52. However, the present invention is not limited to this. For example, as shown in FIG. 4, the through hole of the outer electrode 47 ′ may be an equal diameter hole having the same inner diameter as the inner diameter of the large diameter hole portion 51 ′. In this case, the discharge region A shown in FIG. 2 4 so that the gap between the outer circumferential surface of the inner electrode 54 and the inner circumferential surface of the outer electrode 47 does not change as much as possible with respect to the gap shown in FIG. Is about 15 times as long as the length of the disk-shaped portion 55 in the axial direction. Here, in FIG. 4, the same code | symbol is attached | subjected about the structure same as the structure in FIG.
Industrial applicability
According to the present invention, by configuring as described above, laughing gas is decomposed and NO using air nitrogen is reduced. 2 Synthesis, NOx decomposition, CO 2 It is possible to provide a discharge device that can efficiently perform decomposition and the like.
[Brief description of the drawings]
FIG. 1 is a system diagram of a discharge apparatus in which a laughing gas decomposition experiment was performed using a discharge reactor according to an embodiment of the present invention.
FIG. 2 is a cutaway front view of the main part of the discharge reactor according to the embodiment of the present invention.
FIG. 3 is a sectional view taken along line 3-3 of FIG.
FIG. 4 is a cutaway front view of the main part of a discharge reactor according to another embodiment of the present invention.

Claims (6)

一端にガス入口を、他端にガス出口をそれぞれ有する外側電極及び当該外側電極の内側に配置された内側電極と、
前記内側電極と前記外側電極との間の空間に被処理ガスを流通させるガス流通手段と、
前記空間に前記被処理ガスを流通させた状態で前記内側電極と前記外側電極との間に放電電圧を印加する電源装置と、
からなる放電装置であって、
前記空間は、
前記内側電極の外周面の軸線方向における中間部及び前記外側電極の内周面の軸線方向における中間部によって画成されてなる環状の放電発生領域と、
前記放電発生領域より下流側に前記内側電極の外周面と前記外側電極の内周面とによって画成される環状空間であって、当該環状空間の前記内外側電極間の間隙を前記放電発生領域における前記内外側電極間の間隙より大きくしてなる放電波及領域とを含み、
前記被処理ガスを前記ガス入口から前記ガス出口に向けて流通させつつ前記外側電極と前記内側電極との間に前記所定の放電電圧を印加すると、前記放電発生領域における放電が発生し、当該放電が前記放電波及領域に波及して持続するように、前記放電波及領域の前記間隙を設定してなることを特徴とする放電装置。An outer electrode having a gas inlet at one end and a gas outlet at the other end, and an inner electrode disposed inside the outer electrode;
A gas flow means for flowing a gas to be processed in a space between the inner electrode and the outer electrode;
A power supply device for applying a discharge voltage between the inner electrode and the outer electrode in a state where the gas to be treated is circulated in the space;
A discharge device comprising:
The space is
An annular discharge generation region defined by an intermediate portion in the axial direction of the outer peripheral surface of the inner electrode and an intermediate portion in the axial direction of the inner peripheral surface of the outer electrode;
An annular space defined by the outer peripheral surface of the inner electrode and the inner peripheral surface of the outer electrode on the downstream side of the discharge generating region, wherein a gap between the inner and outer electrodes of the annular space is defined as the discharge generating region. A discharge spreading region that is larger than the gap between the inner and outer electrodes in
When the predetermined discharge voltage is applied between the outer electrode and the inner electrode while flowing the gas to be processed from the gas inlet toward the gas outlet, a discharge occurs in the discharge generation region, and the discharge The discharge device is characterized in that the gap in the discharge spillover region is set such that the spillover continues to spread over the discharge spillover region. 前記外側電極は前記内側電極を同心状に包囲する電極であって、前記内側電極は、前記放電発生領域を形成する円板状部と、前記放電波及領域を形成すべく、当該円板状部の前記ガス出口側端に大径端を連ねた円錐台形部とを備えたことを特徴とする請求項１記載の放電装置。The outer electrode is an electrode that concentrically surrounds the inner electrode, and the inner electrode includes a disk-shaped portion that forms the discharge generation region and the disk-shaped portion to form the discharge spreading region. The discharge device according to claim 1, further comprising: a frustoconical portion having a large-diameter end connected to the gas outlet side end. 前記内側電極は、当該内側電極の備える前記円錐台形部の軸線方向の長さが前記円板状部の軸線方向の長さの３倍以上としてなることを特徴とする請求項２記載の放電装置。3. The discharge device according to claim 2, wherein the inner electrode has an axial length of the frustoconical portion of the inner electrode that is not less than three times the axial length of the disk-shaped portion. . 前記内側電極は、当該内側電極の備える前記円錐台形部の小径端に連なる円柱部を更に備えたことを特徴とする請求項２又は３記載の放電装置。4. The discharge device according to claim 2, wherein the inner electrode further includes a cylindrical portion connected to a small diameter end of the frustoconical portion included in the inner electrode. 前記放電発生領域における、前記内側電極の外周面の軸線方向における中間部と、前記外側電極の内周面の軸線方向における中間部との間の距離は５ｍｍ乃至２５ｍｍであることを特徴とする請求項１乃至４の何れか１項に記載の放電装置。The distance between the intermediate portion in the axial direction of the outer peripheral surface of the inner electrode and the intermediate portion in the axial direction of the inner peripheral surface of the outer electrode in the discharge generation region is 5 mm to 25 mm. Item 5. The discharge device according to any one of Items 1 to 4. 前記放電発生領域の軸線方向の長さは２ｍｍ乃至１０ｍｍであることを特徴とする請求項１乃至５の何れか１項に記載の放電装置。6. The discharge device according to claim 1, wherein a length of the discharge generation region in an axial direction is 2 mm to 10 mm.
JP2003567560A 2002-02-15 2003-02-17 Discharge device Pending JPWO2003068382A1 (en)

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