Reduction & Startup of Pre-reforming Catalysts

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Drying
Heating
Startup
Reduction

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Reduction & Startup of Pre-reforming Catalysts

  1. 1. Reduction and Start Up of Pre-reforming Catalyst Gerard B. Hawkins Managing Director
  2. 2. Prereformer Startup  Drying  Heating  Startup  Reduction
  3. 3. Catalyst Drying For catalyst subjected to low temperatures  Dry using Nitrogen  175 to 250°C  NG can be used below 200°C  4 to 24 hours  Dry air, not suitable for prereduced  First startup of prereduced
  4. 4. Catalyst Heating  Normally heated using nitrogen  Absorbed moisture  Initial heating rate, 50°C per hour  Max temp differential in bed 100°C  At 200°C, 70°C per hour  Heating till peak 400°C, min 370°C  High circ rate, max pd 2 bar
  5. 5. Catalyst Heatingcontinued Warm-up rates  Rapid warm-up minimises energy usage/time  Traditional constraints of equipment  Controllability  Limited by mechanical considerations of vessel  Catalyst, 150-170oC per hour
  6. 6. Catalyst Heating continued Limits on impurities  Oxygen 1% vol  Carbon Dioxide 1% vol  Carbon Monoxide 1% vol  Methane 1% vol  Hydrogen 1% vol  Ethane 100 ppm vol  Sulfur 0.2 ppm vol
  7. 7. Catalyst Heating continued Holding at temperature  Not recommended  2% hydrogen added  Temperature reduced to 350°C
  8. 8. Catalyst Startup When operating temperature has been achieved:  Check for build up of carbon oxides and hydrocarbons  Add of 10% Hydrogen  Followed by steam  Introduce process feed, maintain safe S:C
  9. 9. Condensation  Ensure steam lines warm and low points drained Pre-reformer Cold Pipework Steam
  10. 10. Heating using Natural Gas Using NG as heating medium  No impurities  Immediate startup  50°C per hour, max differential 100°C  At 200°C introduce steam • Min S:C 0.3kg/kg at 200°C • Min S:C 0.5kg/kg at 400°C to 450°C • Increase to design feed and S:C
  11. 11. Reduction of Unreduced Catalyst Unreduced catalyst  As supplied - NiO on support  Active species - Ni Crystallites  Reduction process needed: NiO + H2 Ni + H2O
  12. 12. Reduction of Unreduced Catalyst Reduction aspects  Bed temperature 450°C and 500°C  12 to 16 hours  Hydrogen must be • free of poisons (S, Cl)  Special consideration must be given to the presence in impure hydrogen sources of • carbon oxides • hydrocarbons
  13. 13. Reduction of Catalystcontinued Reduction procedure  Hydrogen set at 15 –25%  Slowly increased to 50%  Regularly check hydrogen levels  Water cooled and collected Reduction complete  85% of reduction water collected  Consumption of hydrogen stopped
  14. 14. Pre-reformer Objectives Remove the restriction on the ID Fan to allow rate increase to Design MTPD Improve efficiency by recovering additional process heat from flue gas  Pre-reformer aims: • Reduce primary reformer firing • Reduce flue gas temperature to ID fan • 4 Year design life • Install during next turnaround • Maintain operating flexibility
  15. 15. Pre-reformer Installation Pre- Heating Re- Heating Gas/Steam Pre-reformer 500ºC 500ºC 450ºC
  16. 16. Pre-reformer Installation  New Pre-Reformer New Vessel and Piping Integration with Flue Duct By-pass Quench Arrangement  Duct Modifications New Coils • Reheat Post Pre-reformer • Cold’ Feed Pre-heater • Natural Gas Pre-heater • Process Air Pre-heater • Superheater Coil Existing Coils • Check New Duty Performance
  17. 17. Pre-reformer Installation  GBHE / HAISO– Technology Supplier  Axial flow with 2 Thermowells  6m3 bed of Catalyst
  18. 18. Planned Procedure •Commissioning smooth minimal changes to normal plant start up – Pre-reformer bypassed initially – Quench controls primary inlet until production achieved – Process gas slowly introduced to pre-reformer –As inlet exit valves fully open, by-pass closed –Quench valve closed as endotherm takes place •

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