Exhaust aftertreatment system using urea water

• Main Authors: AMOU, KIYOSHI, MUKAI, TOSHIFUMI, NISHIOKA, AKIRA, TAGUCHI, YOSHINORI, SUKEGAWA, YOSHIHIRO, HAMADA, YASUNAGA, HAMADA, IKUHISA, KOWATARI, TAKEHIKO, YOKOTA, HIROSHI
• Format: Patent
• Language: English; French; German
• Published: 10.09.2008
• Subjects: BLASTING; CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TOTRANSPORTATION; ENGINE PLANTS IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; HEATING; LIGHTING; MACHINES OR ENGINES IN GENERAL; MECHANICAL ENGINEERING; MIXING, e.g. DISSOLVING, EMULSIFYING, DISPERSING; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; STEAM ENGINES; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TRANSPORTING; WEAPONS

An exhaust aftertreatment system comprises an injector for injecting urea water into an exhaust duct, and a denitration catalyst disposed downstream of the injector with respect to a flow of exhaust gas 1. The exhaust aftertreatment system reduces nitrogen oxides in the exhaust gas 1 by the denitration catalyst 6 while using ammonia produced from the urea water injected from the injector 10. The urea water is injected along a direction of the flow of the exhaust gas within the exhaust duct 3, and a porous plate 12 is disposed in multiple stages in a space of the exhaust duct such that droplets of the injected urea water impinge against the porous plate 12 before reaching a wall surface of the exhaust duct 3. A surface of the porous plate 12 subjected to the impingement of the droplets is arranged to face downstream with respect to the flow of the exhaust gas 1. Deposition of the urea water is prevented by causing film boiling when the droplets impinge against the porous plate 12, and the urea water reflected by the porous plate 12 is uniformly dispersed into the exhaust gas 1. Thus, the urea water is uniformly dispersed into the exhaust gas 1 without increasing a pressure loss of the exhaust gas 1. The urea water is prevented from depositing on the wall surface and producing a precipitate in the form of a solid.