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Ammonia Secondary Reforming Guide

This document discusses secondary reforming in ammonia production. Secondary reforming is used to add nitrogen and reduce methane slip from the primary reformer. It works by further reforming the process gas from the primary reformer with air in a secondary reactor. Key components of the secondary reformer include the burner, mixing volume, and catalyst. Maintaining the right design of these components is important to minimize methane slip during reforming. Different types of burners and catalysts are discussed. Secondary reforming produces a syngas with higher nitrogen and lower methane levels than the primary reformer alone.

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523 views10 pages

Ammonia Secondary Reforming Guide

This document discusses secondary reforming in ammonia production. Secondary reforming is used to add nitrogen and reduce methane slip from the primary reformer. It works by further reforming the process gas from the primary reformer with air in a secondary reactor. Key components of the secondary reformer include the burner, mixing volume, and catalyst. Maintaining the right design of these components is important to minimize methane slip during reforming. Different types of burners and catalysts are discussed. Secondary reforming produces a syngas with higher nitrogen and lower methane levels than the primary reformer alone.

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benon
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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 Ammonia


Primary 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

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