Successful conversion to natural gas...
Transcript of Successful conversion to natural gas...
Successful conversion to natural gas firing
• FCT Combustion• Ricardo Costa
• Adriano Greco
Natural Gas – Pros and Cons
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Natural gas flame needs to be hotter to have the same lengh
Natural Gas – Pros and Cons
4
Accessories – Safe operation
• Natural gas Valve train
Automatic shut off valvesPressure regulatorFlow control valveFlowmeterSafety devices and features according local regulations
• Flame sensor
• BMS• Control of all fuels
• From cooler to the stack – “No short-cuts”
Combustion in Rotary Kilns
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Factors Affecting Burner Operation
Type of fuel
Oxygen in the kiln
Momentum ratio between the burner jets
and secondary air
Kiln, cooler and hood aerodynamics and
relative burner position
Burner tip Design (Atomizer, Gas Nozzle
etc.)
What to get from a good burner
Reduced Energy Costs
Increased Production
Improved Safety & Reliability
Reduced Maintenance Costs
Reduced Emissions
Improved Product Quality
Reduce Rings
Turbulence vs Jet Excitation
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• Turbulent Burner Uses the energy contained in the fuel and/or oxidant
stream to promote the mixing. This concept is based on steady-state, constant jet
streams interfering with each other and with the surrounding secondary air, creating the necessary turbulence.
This principle is applied in the design of most current kiln burners.
• Jet Excitation Phenomenon that a fluid passing at high speed through
a nozzle into a larger chamber, with certain geometric characteristics, would precess around the chamber’s longitudinal axis. This was called “Jet Excitation”.
Burner technology types
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high momentum jet
(Hawthorne & Hottel, 1950’s,
generic public domain
technology available to
all)
- incorporated by FCT
and others in burner
designs
Swirl
(Leuckel, Beer, 1960’s,
public domain technology
available to all )
- incorporated by FCT in
Turbulent Jet Burner0 0.2 0.25 0.5 1.1 Swirl
Classic Turbulent Burner Flame
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Gyro-Therm Burners
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• Use patented “Precessing Jet” technology – no moving parts in a hot and dusty
environment.
• Produce a naturally staged combustion regime
• Causes natural gas to crack to soot, giving high luminosity comparable to oil firing
• Suppresses NOx formation due to fuel rich combustion within flame envelope
• Short bulbous flame with high radiant heat transfer properties - controllable heat flux
profile
• No Primary Air Required
Thermal Profile Comparison
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-40
-20
0
20
40
60
80
100
120
0 5 10 15 20 25 30 35 40 45
Distance from Burner Nozzle (m)
Wa
ll H
ea
t F
lux
(kW
/m^
2)
Oil
Gas: TDJF
Gas: Gyro-Therm
How Significant is the Difference in the Mixing?
Burner Characteristics
• To help understand the Gyro-Therm burner flame a little better it is worth considering the Bunsen burner you may have used during science experiments at school.
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Adjustable openings for
entrainment of air to mix with
the gas prior to igniting
Gas supply
Burner Characteristics
[1] If the air hole is closed then the gas burns only with air that is entrained as the gas exits the nozzle. Due to the low gas velocity air and fuel mixing is poor. This reduced mixing results in incomplete combustion, producing a cooler but brighter yellow flame referred to as the “luminous flame”. The yellow flame is luminous due to small soot particles in the flame which are heated to incandescence. The yellow flame is considered "dirty" because it leaves a layer of carbon on whatever it is heating.
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[2] Air hole slightly open,
[3] Air hole half open,
[4] Air hole fully open (very hot almost
invisible blue flame).
Burner Characteristics
• A turbulent jet gas burner has high momentum to ensure sufficient air is entrained into the flame for complete combustion.
• The high momentum means that fuel and air mix very quickly as the gas leaves the burner tip resulting in low soot formation in the flame, a low flame luminousity (low radiation heat transfer to the bed and walls) and therefore high flame temperature.
• The high flame temperature and air levels in the flame results in high NOx production.
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Burner Characteristics
• Due to the jet of gas precessing around the Gyro-Therm chamber, at any moment in time the gas leaving the burner is burning fuel rich.
• The fuel rich combustion results in high soot formation in the flame, a high flame luminousity (high radiation heat transfer to the bed and walls) and therefore low flame temperature
• The low flame temperature and initial low air levels in the flame results in low NOx production.
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.
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Gyro-Therm Nozzle
Precessing Jet behavior
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Precessing Jet behavior
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Precessing Jet behavior
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Flame difference
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Turbulent Jet Diffusion Burner Gyro-Therm Flame
Results From Cement Plant Installations
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• Client location: USA
• Sattelite kiln with riser duct
• Burner installation: Jan 2017
• Results to date:
• 18% NOx reduction
• 4% Specific heat reduction
• More stable operation = higher productivity
• Direct ROI – Save $ 1 mi in SNCR installation
Results From Cement Plant Installations
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• Client location: USA
• Kiln with ILC Calciner
• Burner installation: May 2017
• Results to date:
• Production increase - + 100 tpd
• Improved fuel consumption
• Decreased ammonia usage
• Improved burning zone coating stability
• Elimination of need for oxygen injection
Gyro-Therm Burners
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For Gas or Gas/Coal Fired Rotary Kilns
• Higher Output
• Lower Fuel Consumption
• Lower NOx Emissions
• Longer Refractory Life
• No Primary Air required
• Flame Shaping Capability
• Stable Flame with High Turndown Ratio