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

InGas 18 months meeting May, 20th/21st 2010 Paris, France. WP B2.3: Exhaust heating/Catalyst concepts Institute for Chemical Process Engineering of Stuttgart University, Germany -USTUTT-. Heat exchanger experiments: Setup for stationary heat exchanger experiments (ICVT)

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

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  1. InGas 18 months meetingMay, 20th/21st 2010Paris, France WP B2.3: Exhaust heating/Catalyst concepts Institute for Chemical Process Engineering of Stuttgart University, Germany -USTUTT-

  2. Heat exchanger experiments: Setup for stationary heat exchanger experiments (ICVT) Stationary results of ICVT prototype Basic adaption of simulation model Setup for stationary heat exchanger experiments (Delphi) Stationary results of Delphi prototype Activity outline • Comparison experimental results ICVT/Delphi • Amplification factors • Pressure drop • Conversion behavior • Conclusions/Outlook • Appendix

  3. Setup for stationary hex experiments • Flowchartoftestrig • General conditions: • Air flows up to 30 m3/h • CH4 conc. up to 5000 ppm • Inflow temperatures: • 20 – 400 °C • Fuel lean operation • Hydrogen-assisted heat up Hood PIR PIR TIR FIC FIC TIR TIR TIR TIR TIR TIR TIR TIR TIR FIC CH4 FID H2 Sensors: • 10 Thermocouples (Type K) Air TC • 2 pressure sensors • THC analytics

  4. Setup for stationary hex experiments • Sensor equipmentof hex prototype (ICVT) Positions of axially aligned Thermocouples 32,5 cm Δ-Pressuremeasurement Additional insulation was appliedaroundtheheatexchanger Due to severe heat losses, the burner interface (tube) was heated during the second set of stationary experiments

  5. Setup for stationary hex experiments • Controlloopforsetpointexperiments Tset Tmax - + • Approach: PID • Heuristic design ofcontrollerparameters FIC • i.e. analysisofstepresponse (of yCH4,in) CH4 • Main advantages: • Stationarytemperatureprofileisreachedmuchfaster • Resultingamplificationfactorisequaltosystemwithoutcontrol: . .

  6. Setup for stationary hex experiments • Experimental procedure (ICVT) • Startup: • Inflow temperature @ 200 °C, Volume flow @ 12 m3/h • H2 in air for fast ignition • H2 + CH4 in air to further heat up the system • CH4 in air until stationary point is reached • Stationaryexperimentsperformed: • Stationary experiments, modified (electrically heated burner interface): • Repetition of 2.I and 2.III (II omitted due to inertia of system) • Setpoint Ttube = Setpoint Tmax

  7. Stationary results of ICVT prototype • Axial temperature: Experiments withactivecontrol • 6 m3/h (GHSV: 24 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3174 ppm (control) • Tmax • Heat sink due to non-insulated connection tube TH,in TC,out TH,out εhex = 91 % TC,in

  8. Stationary results of ICVT prototype • Axial temperature: Experiments withactivecontrol • 11 m3/h (GHSV: 44 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3155 ppm (control) • Tmax • Tmaxshiftedtooutflowchannels • Smallerinfluenceofheat sink εhex = 84 %

  9. Stationary results of ICVT prototype • Axial temperature: Experiments withactivecontrol • 11 m3/h (GHSV: 44 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3155 ppm (control) • Tmax εhex = 81 %

  10. Stationary results of ICVT prototype • Experiments withactivecontrol • Tmax= Tset = 660 °C • Catalyst activity is low and steadily decreasing (see later) • Conversion is distributed over inflow- and outflow channels • Mass transfer limitation • Active surface needs to be increased!

  11. Stationary results of ICVT prototype • Model adaptions I • As can be seen in the previous results, the burner interface acts as a heat sink • Coupling equation between inflow and outflow channel at U-turn: • Fitting parameter • The catalystislessactivethaninitiallyassumed: • Masstransfersurfaceas well askineticparameters (act. energy, preexp. factor) weremodified • Global heatloss was increasedby 3 % • Laminar pressuredropisaccountedforby: • Fitting parameter

  12. Stationary results of ICVT prototype • Resultswithfitted model: nocontrol, noheating • 7 m3/h (GHSV: 28 000 1/h), Tin = 300 °C, yCH4,in= 3500 ppm • Heat sink caused by connection tube for burner

  13. Stationary results of ICVT prototype • Resultswithfitted model: control, heating • 8 m3/h (GHSV: 33 000 1/h), Tin = 300 °C, Theat=Tmax=630 °C • Heat sink relation set to 0 in model

  14. Stationary results of ICVT prototype • Amplificationfactors • Amplification factor is calculated as: • A is corrected by CH4 conversion (ΔTad referred to converted CH4)

  15. Stationary results of ICVT prototype • CH4conversionand yCH4,in • Deactivation! • Tmax is kept constant in both experimental runs (630 °C) • yCH4,in has to change with volume flow • Inverse shape as of A vs. volume flow • Severe decay of catalyst activity between two runs • What happend to the catalyst? • Noheating, conversion • Noheating, yCH4,in • Heating, conversion • Heating, yCH4,in

  16. Stationary results of ICVT prototype • Catalystdeterioration • Linear decayofconversion, leadingto linear decayofTmax • Thermal ageingis not likely. Spallingofwashcoat?

  17. Stationary results of ICVT prototype • Catalystdeterioration • Washcoatcrumbs! • Due to non-fixedspacerstructures (fins), thewashcoat was mechanically not stable!

  18. Setup for stationary hex experiments • Sensor equipmentof hex prototype (Delphi) Delphi hex attestrig Fitting of additional Thermocouples (sliding through center channels) Δ-Pressure measurement Additional insulation

  19. Setup for stationary hex experiments • Axial temperaturemeasurement (Delphi) Positionsof additional TCs Positionsof TCs placedbyKatcon 7 6 outflow U-turn Inflow 4 3* 5 1* 2* *: 2 TCs of same type (redundance) (All positions measured from inflow end)

  20. Setup for stationary hex experiments • Experimental procedure (Delphi) • Startup: • Inflow temperature @ 200 °C, Volume flow @ 11 m3/h • H2 in air for fast ignition • H2 + CH4 in air to further heat up the system • CH4 in air until stationary point is reached • Stationaryexperimentsperformed: • Due toinsulatedburnerinterface, additional heating was not required!

  21. Stationary results of Delphi prototype • Axial temperature: Experiments withactivecontrol • ICVT: 6 m3/h (GHSV: 24 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3174 ppm (control) • Delphi: 7 m3/h (GHSV: 24 000 1/h), Tin = 278 °C, Tset= 630 °C, yCH4,in= 4041 ppm (control)

  22. Stationary results of Delphi prototype • Axial temperature: Experiments withactivecontrol • ICVT: 11 m3/h (GHSV: 44 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3155 ppm (control) • Delphi: 13 m3/h (GHSV: 44 000 1/h), Tin = 293 °C, Tset= 630 °C, yCH4,in= 3484 ppm (control) Kink due to increased cell density! Simulation result taken from DB2.5 report (m=15kg/h). .

  23. Stationary results of Delphi prototype • Axial temperature: Experiments withactivecontrol • ICVT: 15 m3/h (GHSV: 60 000 1/h), Tin = 300 °C, Tset= 630 °C, yCH4,in= 3472 ppm (control) • Delphi: 18 m3/h (GHSV: 60 000 1/h), Tin = 297 °C, Tset= 630 °C, yCH4,in= 4379 ppm (control)

  24. Comparison exp. results ICVT/Delphi • Amplificationfactors Strong influence of axial heat conduction in wall material!

  25. Comparison exp. results ICVT/Delphi • Pressuredrop

  26. Comparison exp. results ICVT/Delphi • Conversionbehavior Wrong measurement due to non-uniform mixing in U-turn section

  27. Conclusions • Experiments with ICVT heat exchanger: • Stationary profiles require long time experiments(very slow system response) • Experimental procedure with controlled Tmax is significantly faster • Insulation/Heating of top section is critical for hex performance • Severe catalyst deterioration • Fitting: • Temperature profiles fit nicely • Pressure profiles fit as well • Fitting is not reliable due to severe catalyst deterioration • Experiments with Delphi heat exchanger: • Results are comparable with ICVT heat exchanger • Worse conversion behavior due to lower cell density (i.e. lower active surface) • Much lower pressure drop than ICVT prototype • Up to now no information regarding catalyst deterioration 27

  28. Outlook • Dynamic experiments: • ICVT prototype was damaged during first experimental attempt (see Appendix) • Heat up tests with fixed ICVT prototype • Heat up tests with Delphi prototype • Stationary experiments with Delphi heat exchanger: • More experimental data to evaluate ageing/deactivation • Fitting: • Fitting of stationary results obtained with Delphi hex • Improvement of pressure relation • Fitting of dynamic experiments as soon as data is available 28

  29. -Appendix- 29

  30. Characterizationofburnersystem • Thermal power output / Lambda ofexhaust 30

  31. Characterizationofburnersystem • Meantemperature / Volume flow 31

  32. Damaged ICVT prototype • Temperature in outflow channels was too high. • Meltdown of channel ends due to compression of hex core • Rapid heat accumulation / pressure increase • Damage only at the very end of outflow channels • Hex core was shortened and will be used again for heat up experiments 32

  33. Test program Delphi benchscale prototype • PHASE I: Stationary tests without burner • Heating up the system with high throughput of hot exhaust (~ 500°C) with low THC concentration (low amplification factor) • Subsequently, different characteristic operating points in engine map are tested, i.e. low/middle/high load at low/middle/high rpm? • Testing different constant exhaust compositions @ λ = 1: • Variation of H2 ,CO/CH4 ratio in exhaust • Can CH4 conversion be boosted by H2 / CO (similar tests at ICVT test bench?) ? • PHASE II: Dynamic tests without burner • Can CH4 light-off be sped-up by increasing CO concentration in exhaust (+ flap) ? • Simulating fuel shut-off under overrun conditions @ constant rpm (possible at test bench?) • How long can system be kept above CH4 light-off ? • λ spikes @ constant rpm+load: monitoring CH4 slip 33

  34. Test program Delphi benchscale prototype • PHASE III: Dynamic tests with burner • Cold start @ constant rpm and burner mass flow • Cold start under NEDC conditions • Burner operation after cold start: • Preventing extinction during fuel shut-off (overrun) @ high rpm • Is addition of CH4 more effective ? • More details need to be defined after dynamic laboratory experiments! • For bench scale, a specifically designed burner system should be ordered (experience will • be gained during laboratory tests) 34

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