Successful conversion to natural gas firing FCT Combustion Ricardo - - PowerPoint PPT Presentation

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

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Accessories – Safe operation

• Natural gas Valve train

Automatic shut off valves Pressure regulator Flow control valve Flowmeter Safety 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 Burner

0 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

20 40 60 80 100 120 5 10 15 20 25 30 35 40 45 Distance from Burner Nozzle (m) Wall Heat Flux (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