Exhaust treatment system and method for treatment of an exhaust gas stream

Patent metadata

Field	Value
Publication number	US-2018221820-A1
Application number	US-201615750168-A
Country	US
Kind code	A1
Filing date	Aug 25, 2016
Priority date	Aug 27, 2015
Publication date	Aug 9, 2018
Grant date	—

Abstract

An exhaust treatment system arranged for treatment of an exhaust stream is presented. The exhaust treatment system comprises a first reduction catalyst device arranged for reduction of nitrogen oxides in said exhaust stream through the use of compounds comprising one or several of carbon monoxide and hydrocarbons, which are comprised in said exhaust stream when said exhaust stream reaches said first reduction catalyst device; a particulate filter which is arranged downstream of said first reduction catalyst device to catch and oxidize soot particles in said exhaust stream; a second dosage device arranged downstream of said particulate filter and arranged to supply an additive comprising ammonia or a substance from which ammonia may be extracted and/or released into said exhaust stream; and a second reduction catalyst device, arranged downstream of said second dosage device and arranged for reduction of nitrogen oxides in said exhaust stream through the use of said additive.

First claim

1 . An exhaust treatment system arranged for the treatment of an exhaust stream resulting from a combustion in a combustion engine, said system comprising:
a first reduction catalyst device, arranged for reduction of nitrogen oxides NO x in said exhaust stream through the use of compounds comprising one or more of carbon monoxide CO and hydrocarbons HC, which are comprised in said exhaust stream when said exhaust stream reaches said first reduction catalyst device; a particulate filter, arranged downstream of said first reduction catalyst device to catch and oxidize soot particles in said exhaust stream; a second dosage device, arranged downstream of said particulate filter and arranged to supply an additive, which comprises ammonia or a substance from which ammonia may be extracted and/or released into said exhaust stream; and a second reduction catalyst device, arranged downstream of said second dosage device and arranged for reduction of nitrogen oxides NO x in said exhaust stream through the use of said additive.

2 . An exhaust treatment system according to claim 1 , wherein:
said internal combustion engine is arranged to emit compounds comprising one or more of carbon monoxide CO and hydrocarbons HC into said exhaust stream; and said first reduction catalyst device is arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least said emitted compounds comprising one or more of carbon monoxide CO and hydrocarbons HC in said exhaust stream.

3 . An exhaust treatment system according to claim 1 , wherein:
a first dosage device is arranged downstream of said combustion engine and upstream of said first reduction catalyst device, and is arranged to supply compounds comprising one or more of carbon monoxide CO and hydrocarbons HC to said exhaust stream; and said first reduction catalyst device is arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of at least said supplied compounds comprising one or more of carbon monoxide CO and hydrocarbons HC in said exhaust stream.

4 . An exhaust treatment system according to claim 1 , wherein:
said internal combustion engine is arranged to emit compounds comprising one or more of carbon monoxide CO and hydrocarbons HC into said exhaust stream; a first dosage device is arranged downstream of said combustion engine and upstream of said first reduction catalyst device, and is arranged to supply compounds comprising one or more of carbon monoxide CO and hydrocarbons HC to said exhaust stream; and said first reduction catalyst device is arranged for reduction of nitrogen oxides NO x in said exhaust stream, through the use of one or more of said supplied compounds and said emitted compounds, wherein said supplied compounds and said emitted compounds comprise one or more of carbon monoxide CO and hydrocarbons HC.

5 . An exhaust treatment system according to claim 1 , comprising:
a control device ( 360 ), arranged to provide one or several control signals, which may be used to control said combustion engine in such a manner that a desired amount of said compounds comprising one or more of carbon monoxide CO and hydrocarbons HC is emitted from said internal combustion engine.

6 . An exhaust treatment system according to claim 1 , wherein said first reduction catalyst device comprises one from among the group of:
a first catalytic reduction catalyst; a first catalytic reduction catalyst followed downstream by a first slip-catalyst, wherein said first slip-catalyst is arranged to oxidize and/or disintegrate said compounds, to assist said first catalytic reduction catalyst with a further reduction of nitrogen oxides NO x in said exhaust stream, and/or to create an exothermic reaction; a first slip-catalyst followed downstream by a first catalytic reduction catalyst, wherein said first slip-catalyst is arranged to oxidize and/or disintegrate said compounds, to assist said first catalytic reduction catalyst with a further reduction of nitrogen oxides NO x in said exhaust stream, and/or to create an exothermic reaction; and a first slip-catalyst, arranged to oxidize and/or disintegrate said compounds, to provide a reduction of nitrogen oxides NO x in said exhaust stream, and/or to create an exothermic reaction.

7 . An exhaust treatment system according to claim 1 , wherein said second reduction catalyst device comprises one from among the group of:
a second selective catalytic reduction catalyst (SCR 2 ); and a second selective catalytic reduction catalyst (SCR 2 ) followed downstream by a second slip-catalyst (SC 2 ), wherein said second slip-catalyst (SC 2 ) is arranged to oxidize a residue of additive, and/or to assist said second selective catalytic reduction catalyst (SCR 2 ) with an additional reduction of nitrogen oxides NO x in said exhaust stream.

8 . An exhaust treatment system according to claim 1 , wherein said exhaust treatment system comprises a system for supply of one or more of said compounds comprising one or more of carbon monoxide CO, hydrocarbons HC and said additive, wherein said system comprises at least one pump, arranged to supply said first and second dosage devices with said compounds comprising one or more of carbon monoxide CO, hydrocarbons HC and said additive, respectively.

9 . An exhaust treatment system according to claim 8 , wherein said system for supply of one or more of said compounds comprising one or more of carbon monoxide CO, hydrocarbons HC and said additive comprises a dosage control device, arranged to control said at least one pump.

10 . An exhaust treatment system according to claim 8 , wherein said system for supply of one or more of said compounds comprising one or more of carbon monoxide CO, hydrocarbons HC and said additive comprises a dosage control device comprising:
a first pump control device ( 378 ), arranged to control said at least one pump, wherein a first administration of said compounds comprising one or more of carbon monoxide CO and hydrocarbons HC is supplied to said exhaust stream with the use of said first dosage device; and a second pump control device, arranged to control said at least one pump, wherein a second administration of said additive is supplied to said exhaust stream with the use of said second dosage device.

11 . An exhaust treatment system according to claim 1 , wherein said first reduction catalyst device is arranged for the reduction of said nitrogen oxides NO x within a reduction temperature interval T red , which at least partly differs from an oxidation temperature interval T ox , within which said particulate filter is arranged for oxidation of incompletely oxidized carbon compounds; T red ≠T ox .

12 . An exhaust treatment system according to claim 1 , also comprising:
a first oxidation catalyst arranged upstream of said first reduction catalyst for a first oxidation and/or decomposition of compounds comprising one or more of nitrogen, carbon and hydrogen in said exhaust stream, and/or to create an exothermic reaction.

13 . An exhaust treatment system according to claim 1 , wherein said particulate filter at least partly comprises a catalytically oxidizing coating, arranged to oxidize one or more of nitrogen oxide NO and incompletely oxidized carbon compounds.

14 . An exhaust treatment system according to claim 1 , wherein said particulate filter at least partly comprises a catalytically oxidizing coating, arranged for reduction of nitrogen oxides NO x .

15 . An exhaust treatment system according to claim 1 , also comprising a second oxidation catalyst, arranged downstream of said first reductio

Assignees

• Scania Cv Ab

Inventors

• Nilsson Magnus
• Birgersson Henrik

Classifications

• F01N2610/02

  the substance being ammonia or urea · CPC title

• F01N2250/02

  filtering and catalytic conversion · CPC title

• F01N3/035 Primary

  with catalytic reactors · CPC title

• B01D53/9477 Primary

  with catalysts positioned on separate bricks, e.g. exhaust systems · CPC title

• F01N3/103

  Oxidation catalysts for HC and CO only · CPC title