Burner Design, Operation and Maintenance on Ammonia Plants

Burner Design, Operation and
Maintenance on Ammonia Plants

 Brief History
 Reformer Burner Types/Design
 Types of Reformers
 Combustion Characteristics
 Excess Air/Heater Efficiency
 Maintenance, Good Practice
 Low Nox Equipment
 Summary
WWW.GBHENTERPRISES.COM

Usage of Fuels on Ammonia Plants
Worldwide
0
50
100
150
200
250
300
350
400
450
Total No
Plants
Natural Gas Heavy Fuel
Oil
Naphtha Syngas Others
Fuels
NumberofOperatingPlants

CURRENT LEGISLATION
LIMITS
Country Start Year Heat release
Furnace Capacity
NOx CO (ppm) Particulates
mg/Nm3
Gas Oil Gas Oil Gas Oil
France 1998 >170 MMBtuh 171 219 - - 5 50
UK 1998 Any 146 219 115
1999 Any 97 171 80
Germany 1996 <170 MMBtuh 122 80
219 85 50
<340 MMBtuh 97 50 5
TA Luft >170:<1020
mmBtuh
171 219 25 87 5-100 50
97 171 25 87 5-100 50
Market demand All 39 73 5 50
171 5 50
Eastern
Europe
As Germany
Italy 1992 >170:<1020
mmBtuh
171 219 5 50
USA - All 30-100

 Brief History
 Burner design
 Burner Types
 Heater Efficiency
 Summary

◦ Historically trial and error
◦ Empirical methods now backed up
with the following sciences
 Chemical engineering
 Process engineering
 Thermodynamics
 Materials engineering
◦ A good understanding of the above
creates good combustion

◦ Computational fluid Dynamic’s (CFD)
is playing a strong role. Good but be
cautious
◦ Can be difficult to predict upsets
 Good for replacing flow modelling
 Model the Burner and the Furnace box to
ensure best possible results
◦ Becoming an essential tool for waste
incineration predictions

 Burner testing in the
manufacturer’s facility should
always be considered
 Confirms burner performance
 Turndown
 CO,CO2,NOX Etc
 Always use the specified fuels
that are to be used in service
 Highlights flame envelope and
lift off limits, pilot/light up
issues.
 Air flow distribution

 Brief History
 Burner design
 Types of Reformers Reformer
 Burner Types/Design
 Summary

Side Fired
Top Fired
Terraced wall

 Natural Draft
 Forced Draft
 Premix
 Post Mix
 Low Nox
◦ Fluegas Recirculation
◦ Staged Air
◦ Staged fuel
 Single fuel/Dual fuel

Gas Nozzle
Primary Air
Primary Air
Pre-Mix Burners
Venturi
Primary
Fuel
• Fuel & air mixed before
combustion zone
• Fuel pressure drop occurs in the nozzle.

Premix
Gas
Burner

Nozzle Mix Gas Burner
Included
Angle
Burner Block
Burner Throat
Port Circle
Heater
Refractory
Flame Holder
Pilot Gas
Air
Fuel Connection
FUEL

Nozzle
Mix Gas
Burner
Top or
Bottom Fired

Nozzle
Mix Gas
Burner
Side fired

Nozzle Mixing Gas Burner
Advantages
• No possibility of flashback
• To some extent, the ability to burn a
wide variety of fuels with differing
heating values.
• A high turndown ratio

 Brief History
 Reformer Burner Types/Design
 Summary

 Increasing excess air
• reduces flame length
• reduces particulates
• increases NOx to a peak, further introduction of air leads
to a reduction
• Increasing liberation
• increases flame length

• Increasing fuel viscosity
• increases flame length
• increases particulates
• reduces NOx levels
• Increasing combustion air temperature
• reduces particulates
• increases NOx levels

Draught Inches WG
-13
-27
-41
-55
Top firebox
Bottom Firebox
FD Section
Atmosphere
After
Convection
After damper
After ID Fan
Atmosphere
13
27
41
55
83

x100
outputGross
outputUseful
Efficiency 





=
Heater Efficiency

 Burners can be maintained on or off line
◦ On line less popular due to safety concerns, guns
can be with drawn
◦ basic tip changes can be carried out
◦ potential to change burner settings

◦ Off line during shutdowns (every 3-4 years)
◦ Relatively easy to perform
 Need for access
◦ Important to maintain settings
 tile to gun position
 tip port dimensions
 surface finish of holes
 centricity of gun
 condition of tile and security of fixings
 condition of metallurgy (oxidation)

 Check Burner gas Pressures
◦ at the burners, not the just the rail
pressure
 Check Combustion air pressures
◦ All to often the system is not balanced
correctly
 For oil firing
◦ it is very important atomising steam is dry
and at the correct temperature

◦ Currently being fitted on new plants
◦ More difficult to control
◦ The very nature of low Nox burner designs requires
the flames to be produced in a much slower manner
◦ Even more sensitive to dimensional changes during
maintenance, burner’s tend to be more complex
◦ Flames tend to be less well defined, with large
whispery edges

 Types
◦ Staged Air
◦ Staged Fuel
◦ Flue Gas Recirculation
 Integral with the burner
 external to the burner
◦ Combination of all above

 Good Combustion, this can only be
achieved if the following is
considered.
 Attention to detail
◦ Good maintenance
◦ Good operation
◦ Good design
 Partnership between:- Operation,
Maintenance and Design.

◦ You've carefully thought out all the angles
◦ You've done it a thousand times
◦ It comes naturally to you
◦ You know what you're doing, its what you've
been trained to do your whole life
◦ Nothing could possibly go wrong, right ?

Think Again !

Burner Design, Operation and Maintenance on Ammonia Plants

Burner Design, Operation and Maintenance on Ammonia Plants

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Burner Design, Operation and Maintenance on Ammonia Plants