Development of Current and Future Diesel After Treatment Systems

Transcription

1 Development of Current and Future Diesel After Treatment Systems Pakorn Bovonsombat, Byung-Sun Kang, Paul Spurk, Harald Klein, Klaus Ostgathe Degussa Metals Catalysts Cerdec AG Rodenbacher Chaussee 4, P.O.Box 1351 D Hanau-Wolfgang, Germany Content: 1

2 Content: Diesel Legislation Legislation Total cycle emissions in NEDC-cycle in [g/km] CO HC + NO x HC NO x PM EURO III EURO IV EURO III and EURO IV legislation for diesel passenger cars in NEDC - cycle. Legislation Total cycle emissions in [g/kwh] CO NMHC HC NO x PM ESC- EURO III Test Cycle EURO IV ETC- EURO III Test Cycle EURO IV EURO III and EURO IV legislation for heavy-duty trucks. 2

3 Thailand Diesel Legislation Legislation for Light Duty Diesel Total Cycle Emissions in R-83 Cycle (g/km) Vehicle Category CO HC+NOx PM Less than 6 passengers (0.90) 0.08 (0.10) More than 6 passengers ( ) ( ) Less than 2,500 Kg GW ( ) = Values for Direct Injection Legislation for Heavy Duty Diesel (Euro II) Total Cycle Emissions in R-49 Cycle (g/ kwh) Vehicle Category CO HC NOx PM More than 9 passengers GW greater than 3,500 Kg. NOx-PM Trade-off PM [g/km] 0.05 optimized combustion + better fuel engine measure NO x-reduction optimized combustion engine measure particulate reduction EURO III particulate aftertreatment EURO IV NO x-aftertreatment NO x [g/km] NO x /PM trade-off-curve for passenger. cars. Emission values refer to NEDC- cycle. Similar principle is valid for heavy-duty trucks. 3

4 Requirement of NOx Conversion Efficiency NO x emission [g/km] 0,825 0,725 0,625 0,525 0,425 0,325 NOx emission EU 4 legal limits required NOx conversion passive DeNO x urea SCR NO x adsorber required NO x conversion [%] 0, , inertia test weight [kg] Content: 4

5 Function of Diesel Oxidation Catalyst Engine-out : CO Unburned HC PM NO x Catalytic Converter C m H n + (m+0.25n) O 2 = m CO n H 2 O CO O 2 = CO 2 CO 2 H 2 O Reduced emission of PM and NO x * * Passive NO x conversion rate: Max. 10 % Performance of Diesel Oxidation Catalyst total cycle conversion [%] NOx CO HC PM 70 g Pt/cuft, fresh V cat = 2.5 l 2.0 L DI CR ITW = 1,587 kg 406 wt. ppm S Diesel oxidation catalyst for passenger car performance in NEDC cycle. 41 5

6 Content: Basic Concept of NO x Adsorber Red NO + ½ O 2 NO3 - NO 2 NOx Pt adsorber N 2 NO x Pt NO 3 - NOx adsorber Support Support NO x - Adsorption NO x - Reduction Chemical model of NOx storage catalyst Source: N. Miyoshiet et al, SAE (1995) 6

7 Operation Concept of NO x Adsorber I lean phase; storage of nitrogen oxides λ 1 Time NO CO, HC. PM... Clean exhaust II rich phase; regeneration of the adsorber Operation principle of diesel NO x storage catalyst. Conversion Efficiency of NO x Adsorber Model Gas composition: Simulation of typical diesel exhaust gas composition Adjustment lean / rich sumulation: 60 s lean / 10 s rich setting; SV = 30, NO x conversion [%] Temperature in front of catalyst [ C] NOx conversion as function of temperature in front of diesel Nox-storage catalyst Model gas test 7

8 Content: Particulate Filter System exhaust Fibre 1.Diffusion 2,3. Inertia effects Surface filter Fibre filter 8

9 Number of Regenerations vs. PM Raw Emission Number of regenerations Distance between regenerations [km] Vehicle A (0.112 g/km) Vehicle B (0.047 g/km) PM raw emissions measured in NEDC-cycle Calculation of required filter regeneration cycles during 80,000 km in NEDC- cycle. Particulates loading in the filter: 10 g. Type of Filter Regeration Examples of filter regeneration methods. 9

10 Content: Basic System of SCR urea (NH 2 ) 2 CO SCR catalyst (S) 4NH 3 + 4NO + O 2 4N 2 + 6H 2 O 2NH 3 + NO + NO 2 2N 2 + 3H 2 O 8NH 3 + 6NO 2 7N H 2 O exhaust V S O Pre-catalyst (V) 2NO + O 2 2NO 2 4HC + 3O 2 2CO 2 + 2H 2 O 2CO + O 2 2CO 2 Guard catalyst (O) 4NH 3 + 3O 2 2N 2 + 6H 2 O Operation principle of urea-scr system. 10

11 Engine Test Result of Urea-SCR (MVEG A) NO x concentration [vppm] NOx raw NOx after SCR system NH3 after SCR system N2O after SCR system ECE 22 % EUDC 83 % total 63 % NH 3 / N 2 O concentration [vppm] time [s] Durability of Urea-SCR (MVEG A) NO x conversion [%] fresh 50 hrs 100 hrs 150 hrs 200 hrs conditioned aging status ECE part EUDC part total 11

12 Content: Summary: 1. From 2000 onwards, diesel emission legislation based on modified EU-I & -II has been enforced in China, India and Thailand. 2. Diesel oxidation catalyst as the basic technology for diesel aftertreatment, combined with engine calibration can fulfill EU-III limits. 3. For EU-IV, diesel oxidation catalyst with NO x aftertreatment and/ or with particulate filter, combined with improved engine technology could be required. 4. System developments of reducing NO x over 50 %, e.g., NO x adsober and Urea-SCR, are ongoing. 5. Particulate filter can trap PM with efficiency over 90 %. To develop filter regeneration method is a main challenge. 12

13 Thank you for your attention!!! 13