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Method and apparatus for processing exhaust gas

外国特許コード F110004143
整理番号 RX03P67WO
掲載日 2011年7月12日
出願国 欧州特許庁(EPO)
出願番号 08711388
公報番号 2123344
公報番号 2123344
出願日 平成20年2月15日(2008.2.15)
公報発行日 平成21年11月25日(2009.11.25)
公報発行日 平成26年1月22日(2014.1.22)
国際出願番号 JP2008052558
国際公開番号 WO2008102708
国際出願日 平成20年2月15日(2008.2.15)
国際公開日 平成20年8月28日(2008.8.28)
優先権データ
  • 2008JP052558 (2008.2.15) WO
  • 特願2007-041449 (2007.2.21) JP
発明の名称 (英語) Method and apparatus for processing exhaust gas
発明の概要(英語) Disclosed are a method and an apparatus for processing an exhaust gas, which enable to suppress decrease of pH and increase of ORP of a mixture of an aqueous solution of a reducing agent and an aqueous alkali solution circulated within a wet reactor comprising a reduction reaction region and an oxidation reaction region.
The method and apparatus enable to prevent deterioration of the mixed aqueous solution, and can be continuously operated for a long time.
Specifically, the ORP and pH of the mixed aqueous solution of the aqueous solution of a reducing agent and the aqueous alkali solution to be circulated within the wet reactor are measured, and a fresh aqueous solution of a reducing agent and a fresh aqueous alkali solution are supplied, if necessary, into a reservoir unit arranged in the lower part of the wet reactor so that the ORP and pH of the mixed aqueous solution are kept within predetermined ranges.(see diagramm)
特許請求の範囲(英語) [claim1]
1. A method for processing an exhaust gas, comprising the following steps: introducing a radical gas generated from air by an atmospheric pressure low-temperature nonequilibrium discharge plasma reaction, and an exhaust gas containing nitrogen oxide separately to an oxidation reaction area of a wet reactor having an oxidation reaction area in a lower part and a reduction reaction area in an upper part,
allowing the nitrogen oxide in the exhaust gas to react with the radical gas to oxidize the nitrogen oxide to NO 2 in the oxidation reaction area, bringing the oxidized gas containing NO 2 into contact in the reduction reaction area with a mixed aqueous solution consisting of a reducing agent aqueous solution and
an alkaline aqueous solution introduced into the reduction reaction area to reduce the NO 2 to a nitrogen gas (N 2), and discharging the nitrogen gas into atmospheric air from a top of the wet reactor; in order to keep the pH value and the oxidation-reduction potential (ORP) value of the mixed aqueous solution to be introduced into the reduction reaction area, measuring the pH and the ORP of the mixed aqueous solution, and supplying a fresh reducing agent aqueous solution and a fresh alkaline aqueous solution to a reservoir unit of the mixed aqueous solution provided in a lower part of the wet reactor on the basis of the measurement results; and circulating the mixed aqueous solution into the upper portion the reduction reaction area from the reservoir unit of the mixed aqueous solution.
[claim2]
2. The processing method according to claim 1, wherein the atmospheric pressure low-temperature non-equilibrium discharge plasma reaction is conducted by using an ozonizer of a silent discharge system at an applied voltage of substantially 10 kV, within a frequency range of 0.42 to 6.82 kHz.
[claim3]
3. The processing method according to claim 1 or 2, wherein the reducing agent aqueous solution contains an inorganic sulfur-containing reducing agent selected from sodium sulfite, sodium sulfide and sodium thiosulfate, and the alkaline aqueous solution contains a hydroxide of an alkaline metal or an alkaline earth metal selected from sodium hydroxide, calcium hydroxide and potassium hydroxide.
[claim4]
4. The processing method according to anyone of claims 1 to 3, wherein the mixed aqueous solution introduced into the reduction reaction area has a pH of 6 to 10 and an ORP of -50 to 100 mV.
[claim5]
5. The processing method according to anyone of claims 1 to 3, wherein the mixed aqueous solution introduced into the reduction reaction area has a pH value of 8 to 9, and an ORP value of -50 to 0 mV.
[claim6]
6. The processing method according to anyone of claims 1 to 5, wherein the wet reactor is a tower reactor or a column reactor.
[claim7]
7. The processing method according to anyone of claims 1 to 6, wherein the exhaust gas is the one discharged from a flue and smoke tube boiler or from a diesel engine.
[claim8]
8. The processing method according to claim 1, wherein the reducing agent aqueous solution and the alkaline aqueous solution are supplied into a line branched from a mixed aqueous solution circulation line through a pH meter and a ORP meter and coming to the mixed aqueous solution reservoir, at the downstream side of the pH meter and the ORP meter.
[claim9]
9. A processing apparatus of an exhaust gas which is characterized by comprising: a wet reactor (3) having an oxidation reaction area (4) in a lower part and a reduction reaction area (5) in an upper part; a mixed aqueous solution reservoir unit (1b) provided under the oxidation reaction area in the wet reactor; an atmospheric pressure low-temperature nonequilibrium discharge plasma reaction unit (1) for generating a radical gas from air; a radical gas introducing line (1a) for introducing the radical gas generated in the plasma reaction unit to the oxidation reaction area; an exhaust gas introducing line (2b) for introducing an exhaust gas containing nitrogen oxide to the oxidation reaction area separately from the radical gas introducing line; a mixed aqueous solution circulation line (9) for circulating a mixed aqueous solution consisting of a reducing agent aqueous solution and an alkaline aqueous solution and introducing the mixed aqueous solution into the reduction reaction area from the mixed aqueous solution reservoir; a pH meter and an ORP meter (12, 13) provided in a route which is branched from the mixed aqueous solution circulation line and leads to the mixed aqueous solution reservoir unit; and a reducing agent aqueous solution supplying line (7a) coming from a reducing agent aqueous solution tank (7) and an alkaline aqueous solution supplying line (8a) coming from an alkaline aqueous solution tank (8), connected to the route on the downstream side of the pH meter and the ORP meter, respectively, wherein the reducing agent aqueous solution and the alkaline aqueous solution are supplied, on the basis of the measured pH and ORP values of the circulating mixed aqueous solution, into the mixed aqueous solution reservoir unit from the aqueous solution supplying line so that the pH value and the ORP value of the mixed aqueous solution consisting of the reducing agent aqueous solution and the alkaline aqueous solution to be introduced into the reduction reaction area fall within predetermined ranges.
[claim10]
10. The processing apparatus according to claim 9, wherein the atmospheric pressure low-temperature nonequilibrium discharge plasma reaction unit is an ozonizer of a silent discharge system.
[claim11]
11. The processing apparatus according to claim 9 or 10, wherein the wet reactor is a tower reactor or a column reactor.
[claim12]
12. The processing apparatus according to anyone of claims 9 to 11, wherein a partition having a plurality of through holes is provided between the reduction reaction area and the oxidation reaction area.
  • 出願人(英語)
  • OSAKA PREFECTURE UNIVERSITY
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • 発明者(英語)
  • KUROKI TOMOYUKI
  • OKUBO MASAAKI
  • YAMAMOTO TOSHIAKI
  • FUJISHIMA HIDEKATSU
  • OTSUKA KEIICHI
国際特許分類(IPC)
欧州特許分類/主・副
  • B01D053/56
  • B01D053/79
  • F01N003/035
  • F01N003/04
  • F23J015/04
  • L01D251/104
  • L01D251/20
  • L01D251/304
  • L01D251/404
  • L01D251/604
  • L01D258/01D
  • R01N570/14
  • R23J219/40
指定国 Contracting States: AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR
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