Ingas 18 months meeting may 20th 21st 2010 paris france
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InGas 18 months meeting May, 20th/21st 2010 Paris, France. SPB2. INGAS 18 months meeting, Paris, 20./21.5.2010. Introduction of work Pd-TWC results Effect of H 2 O on CH 4 oxidation Methane Steam Reforming Secondary emissions Base characterizations, Lightoff T 50

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InGas 18 months meeting May, 20th/21st 2010 Paris, France

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Ingas 18 months meeting may 20th 21st 2010 paris france

InGas 18 months meetingMay, 20th/21st 2010Paris, France

SPB2

INGAS 18 months meeting, Paris, 20./21.5.2010


Contends

Introduction of work

Pd-TWC results

Effect of H2O on CH4 oxidation

Methane Steam Reforming

Secondary emissions

Base characterizations, Lightoff T50

Effect of hydrothermal aging

Effect of Sulfur poisoning

Summery

Operation Strategy

CH4 and NOX abatement under stoichiometric conditions

Summery

NOX abatement under lean conditions

Deriving of a Operation Strategy

Contends


Experimental setup of the laboratory test system

Exhaust air

Exhaust air

Reactors

Reactors

Analytics

Analytics

H

H

O

O

-

-

2

2

Evaporator

Evaporator

detector

detector

Exhaust air

Exhaust air

Synth

Synth

. gases

. gases

Experimental setup of the laboratory test system


Introduction of work

Synthetic gas tests with two test samples delivered by Ecocat.

Lightoff temperature T50

Steady state temperature programs to heat up (10K/min) the catalyst and cool down after reaching 600°C.

Measuring CO, CO2, CH4, NOX, NO, N2O, O2, Lambda, NH3, H2

Gasmix study

5 stationary temperatures with concentration programs to increase and decrease species concentration.

Measuring CO, CO2, CH4, NOX, NO, N2O, O2, Lambda, NH3, H2

Hydrothermal aging

Aging 10h at 800°C with water and air, aging 10h at 950°C with water and air.

Sulfur poisoning

Sulfation at 300°C up to 1g/Lcatalyst sulfur.

Desulfation with temperature program at Lambda = 1 (dT~10K/min up to 750°C)

Desulfation with temperature program at Lambda = 0.9 (dT~10K/min up to 750°C)

Introduction of work


Effect of h 2 o on ch 4 oxidation

H2O in gas-stream inhibits the CH4 conversion.

Engine exhaust contains ~12Vol.% H2O.

Effect of H2O on CH4 oxidation

with H2O

with H2O

with H2O

w/o H2O

w/o H2O

w/o H2O

CH4 conversion with

CO, CO2, NO, O2, H2 in feed.

CH4 oxidation only with O2

CH4 oxidation only with NO


Methane steam reforming

In first step CH4 was formed to CO and 3H2.

Further the formed CO was converted by H2O to H2 and CO2.

The water gas shift reaction with CO was activated at lower temperatures between 230°C and 350°C.

Methane Steam Reforming

YCH4 = 1500ppm , YH2O = 10Vol.%

YCO = 0.6Vol.% , YH2O = 10Vol.%


Secondary emissions

At temperatures below 200°C CO has interaction

with NOX and some NH3 was formed.

When CH4 has Lightoff at 420°C, about

100ppm NH3 was formed.

Secondary emissions

When CO react with NOX, some N2O was formed until CH4 Lightoff.

No significant N2O was formed during and after the CH4 Lightoff at lambda=1.


Sv 50000h 1 @ base characterizations np 8621 @ sv 100000h 1

Gasmix 1 and 2 typify real gas concentration at corresponding engine load point.

Temperature increase and decrease show hysteresis effect in concentrations.

SV=50000h-1 @ Base-Characterizations NP-8621 @ SV=100000h-1

Sample condition: 5h @ 600°C @ lambda = 1 gas compositon.

  • Gasmix-1 :CH4= 1500ppm*, CO=0.6Vol.%,H2=0.1Vol%, NOX=1300ppm, O2~ 0.537Vol.%, H2O=10Vol%, CO2=10.7Vol.%, N2 balance (Lambda = 1, SV~50000h-1)

  • Gasmix-2 :CH4= 1000ppm*, CO=0.63Vol.%,H2=0.1Vol%, NOX=2600ppm, O2~ 0. 405Vol.%,

  • H2O=10Vol%, CO2=10.7Vol.%, N2 balance (Lambda = 1, SV~100000h-1)


Effect of hydrothermal aging

„Basis“ means base-characterization with 5h @ 600°C and lambda=1 aging.

“Aging1” means characterization after 10h @ 800°C hydrothermal aging.

“Aging2” means characterization after 10h @ 950°C hydrothermal aging.

TWC has excellent durability against hydrothermal aging.

SV = 50.000h-1

SV = 100.000h-1

Tepm. increase

Tepm. increase

Temp. decrease

Temp. decrease

CH4 Lightoff T50 [°C]

CH4 Lightoff T50 [°C]

Basis

Aging 2

Basis

Aging 2

Aging 1

Aging 1

Effect of hydrothermal aging


Effect of sulfur poisoning

“Aging1” means base-characterization after 800°C hydrothermal aging.

“after sulfation” means characterization after 1g/Lcatalyst sulfation.

“DeSOX1” means characterization after Lambda=1 desulfation. (TPD up to 750°C)

“DeSOX2” means characterization after Lambda=0.9 desulfation. (TPD up to 750°C)

Stoichiometricdesulfation seems to remove the whole sulfur.

SV = 50.000h-1

SV = 100.000h-1

Temp. increase

Temp. increase

Temp. decrease

Temp. decrease

CH4 Lightoff T50 [°C]

CH4 Lightoff T50 [°C]

Aging 1

after sulfation

after sulfation

DeSOx 1

DeSOx 2

Aging 1

DeSOx 1

DeSOx 2

Effect of Sulfur poisoning


Summery pd twc results

After 5h @ 600°C the Lightoff temperatures are around 400°C.

No critical secondary emissions were observed.

Pd-TWC shows good resistance against hydrothermal aging.

Lambda=1 desulfation seems the whole of sulfur removed.

During cold start, the combustion should be adjusted so, that more CO and / or H2 in the exhaust gas would be available.

Summery “Pd-TWC results”


Ch 4 and no x abatement under stoichiometric conditions

CH4 and NOX abatement under stoichiometric conditions

Laboratory tests with synthetic gas test bench.


Target for future emission standards

To achieve the emission standards we need to improve the CH4 conversion.

To identify the best possible operation strategy a parameter study was done.

The most sensitive parameter for three way operation was air/fuel ratio.

The air/fuel ratio was varied by increasing the reducing agents.

Target for future emission standards

Lightoff - T50 [°C]

CH4 mass in NEDC [g/km]

NEDC cycle


Impact of lambda variation co variation

upstream catalyst

Impact of lambda variation (CO variation)

If upstream CO concentration increase, CH4 conversion increase too (right picture).

When CH4 has been converted H2 was detected.

Increasing CO concentration increases H2 forming proportional. (WGS reaction)


Impact of lambda variation co variation1

It’s possible to increase the CH4 conversion efficiency by increasing the CO concentration.

The best CH4 conversion has been reached between air/fuel ratios≤1.

High level of H2 has formed by steam reforming and watergas shift reactions.

To investigate the role of the H2 concentration in exhaust raw emissions, some tests with dosed H2 were performed.

Impact of lambda variation(CO variation)


Ingas 18 months meeting may 20th 21st 2010 paris france

Impact of lambda variation (H2 variation)

H2 has significant impact on CH4 conversion too!

  • The dosed H2 becomes oxidized in catalyst and increases the catalyst temperature.

  • This oxidation of H2 can be done with reducible reacting agents from the gas phase as well as

  • oxidized agents from the catalyst surface.


Ch 4 and no x abatement under stoichiometric conditions1

CH4 and NOX abatement under stoichiometric conditions

  • A effective operation strategy can be summarized in some headwords:

    • Ideal operation point is addicted to temperature and lambda.

    • Rich engine operating mode during cold start can improve CH4 conversion.

    • After reaching CH4 Lightoff, switch to normal stoichiometric engine operation mode.


The characterization of engine raw emissions at avl

The characterization of engine raw emissions at AVL

The engine test bench results shows the possibility to increase the CO an H2 concentration by engine calibration.

The catalyst temperature can be increased by this way.

This first engine test results show a positive trend regarding an effective engine cold start strategy.


Summery

To abate CH4 and NOX under stoichiometric conditions its helpful:

to realize slightly rich conditions during cold start.

to increase the CO concentration in engine raw emissions.

to increase the H2 concentration in engine raw emissions.

to increase the exhaust gas temperature.

Summery


No x abatement under lean conditions

Under lean conditions the TWC can’t convert NOX.

With the NSC we have the possibility to store the NOX during lean operation and convert them under rich conditions.

To picture the NOX regeneration ability with CH4, some systematic tests were performed.

Periodic lean/rich switch (lean-time t=3min, rich-time t=20s) with different gas compositions at rich-cycle.

NOX Abatement under lean conditions

1st rich-gas mixture at Lambda=0.935

2nd rich-gas mixture at Lambda=0.94

3rd rich-gas mixture at Lambda=0.935

4th rich-gas mixture at Lambda=0.935


Test result

Ineffective NSC regeneration only with CO and CH4 upstream-catalyst.

No benefit because WGS and Steam Reforming reactions.

If H2 is present in feed upstream NSC good regeneration is possible at low temperatures.

Test result

  • NSC material with ~130g/ft3 Pt/Pd/Rh: 10/2/1 and aged 20h @ 700°C.

  • Its possible to trigger the H2-forming for NSC regeneration on a prelocated TWC.

  • Only with high H2 concentrations upstream, a NSC regeneration is possible.


No x abatement under lean conditions1

To regenerate the stored NOX under rich conditions H2 upstream NSC is necessary.

For a application together with an CNG engine, the H2 can be provided by engine raw emissions at every engine load under rich conditions.

If the NSC would be placed after TWC, the CO conversion by watergas shift under rich conditions can provide H2 additionally.

NOX Abatement under lean conditions

+

Engine raw emissions

H2 forming on TWC


Deriving of a operation strategy

At first it should be focussed on CH4 abatement at cold start.

The first part of the NEDC could be performed under slightly rich conditions with high CO and H2 concentrations in exhaust gas, to increase the catalyst temperature.

The second part could start after reaching CH4 Lightoff temperature upstream TWC. Now we got nearly 100% CH4 conversion and the focus can switch to NOX abatement under lean conditions. If the engine operation mode has been switched from slightly rich cold start mode to lean mode, a NSC can store the NOX during lean phases. If the NOX storage capacity is nearly at maximum, the NSC can be regenerated by a short rich phase. Depending on NSC volume and NOX engine emissions a specific number of lean/rich cycles have to be performed to achieve the NOX emission regulations.

Deriving of a Operation Strategy


Backup

Backup


Test conditions

When NOX outlet-concentration become steady state, the NOX storage level during adsorption (lean) reach his maximum.

Then the reduced NOX mass in rich phase is the same amount becoming adsorbed in the next lean phase.

The averaging over 5 cycles represents the regenerated NOX mass.

Test-conditions


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