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. 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. 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
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
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
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. 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. 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
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
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
•