Ammonia Plant - Secondary Reforming
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Why have a Secondary Reformer ? Need nitrogen to make ammonia Wish to make primary as small as possible Wish to minimise methane slip since methane is an inert in the ammonia synthesis loop Other methods of achieving this Braun Purifier process Can address all these with an air blown secondary
Transcript of Ammonia Plant - Secondary Reforming
Ammonia Secondary Reforming
By: Gerard B. Hawkins
Managing Director, CEO
Why have a Secondary Reformer ?
Need nitrogen to make ammonia
Wish to make primary as small as possible
Wish to minimise methane slip since methane is an inert in the ammonia synthesis loop
Other methods of achieving this Braun Purifier process Can address all these with an
air blown secondary
Secondary Reforming
Secondary has three key components Burner Gun Mixing Volume Catalyst All three must be right to obtain minimum
methane slip During normal operation difficult to tell
which one is causing a problem In general need to shut down and inspect
Secondary Reforming Catalyst is typically loaded on top of inert
balls or lumps (low silica) Refractory arch in base of secondary
allows for Support of bed and inerts Collection of gases On top of bed install a heat shield - made
of • Tiles • Large catalyst pellets
Gives additional activity Large enough that moving catalyst is
very difficult
Secondary Reforming
Number of different types of burner gun • John Zinc Shower head type • JMC (Synetix) High Intensity Ring Burner • Haldor Topsøe’s ring burner
• Similar to ours Aim of burner is to • Mix intimately the process gas and oxidant
(air) • Evenly distribute air • Ensure no burning on burner tips
High Intensity Ring Burner Design
Secondary Reforming Mixing Volume
If there is insufficient mixing volume, • Variation of bed inlet temperature • Variation of bed inlet composition • Leads to poor usage of bed • High methane slip • Can change catalyst to improved version • Reduce catalyst volume • Increased mixing volume
Secondary Reforming Catalysts
Catalyst is robust Can not be poisoned due to high
temperature operation Poisons will be passed to next unit
operation Can be affected by high temperatures
Will get color changes Can get bypassing Leads to wide variations in flow per unit
volume Leads to higher than expected ATE’s
Comparison to other Technologies
Name Methanol Hydrogen Ammonia Ex Primary
Ammonia Ex Secondary
H2 70-73 70-73 68-71 54-58 CO 14-16 13-16 6-9 10-12 CO2 7-9 6-11 10-12 8-10 CH4 2-3 1-5 8-12 0.1-1.0 N2 0-1 0-1 0-1 22-26
