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Pre-reformer in the flowsheet * positioned upstream of the steam reformer * uses a specialized high activity catalyst based on Ni * reaction involves conversion of hydrocarbons to a mix of CH4, CO, CO2 and H2 Pre-reformers - sometimes included at the original design stage - also can be added to existing units to uprate the plant
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Introduction Pre-Reformer Flowsheet
Options By:
Gerard B. Hawkins
Managing Director, CEO
Steam Reforming Section - Pre-reformer
Single adiabatic reactor • upstream of the steam reformer • uses high activity Ni based catalyst
Converts hydrocarbons to methane, CO, CO2 and H2 • Eliminates C2 and higher hydrocarbons
from feed • Makes life easy for the steam reformer
!!
Steam Reforming Section - Pre-reformer: Why ?
High efficiency/low energy plants Low steam export – benefit if steam not
required Smaller and high heat flux reformers
• Lower reformer capex (offset by pre-reformer capex)
Simplified and robust steam reformer operation
Means to deliver feedstock flexibility (not only means) between lighter and heavier feeds
Steam Reforming Section - Pre-reformer: Why Not ?
Additional equipment • Capex (offset by smaller reformer ?) • Opex (catalyst; maintenance; ….)
Complicated and delicate pre-reformer operation • Easily damaged expensive catalyst
Low steam export – problem if steam export valued/required
Economics suggest that pre-reformer is not the only solution if feedstock flexibility is required
Process Steam
Hydrocarbon Feed
HDS
Reformed Gas
Fuel
ZnO
Steam Generation and Superheating
Combustion Air
Pre-heat
Pre-reformer
Steam Reforming Section - Pre-reformer: Scheme without Re-heat
Process Steam
Hydrocarbon Feed
HDS
Reformed Gas
Fuel
ZnO
Steam Generation and Superheating
Combustion Air
Pre-heat
Pre-reformer
Steam Reforming Section - Pre-reformer: Scheme with Re-heat
Steam Reforming Section - Pre-reformer: Why or Why Not Re-heat ?
Endothermic steam reforming at inlet (both beds) Methanation causes exotherm with naphtha
525 500 475 450 400 350
Tem
pera
ture
(oC
)
Natural Gas
Inlet Exit
947 932 887 842 752 662
Temperature ( oF)
Naphtha
Inlet Exit
Summary
High level review of syngas flowsheets
Key differences and options highlighted
Increased awareness but many further layers of detail exist