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Assessment of a Gas Quality Survey for Interchangeability
David Rue, William Liss
Gas Technology Institute
Algonquin Gas Pipeline
Northeast Stakeholders Group
June 15, 2006
Regional Natural Gas Composition Variations Exist
Average Natural Gas Composition -- Twenty Six US Cities
Source: Gas Technology Institute
Non-Methane Natural Gas Constituents
12
34
56
78
910
1112
1314
1516
1718
1920
2122
2324
2526
Survey City Number
0
5
10
15
20Non-Methane Constituents (Mole%)
Ethane Propane Butanes+ Inerts
Natural Gas and LNG
Adjust gases are typical U.S. natural gases at city gates (GRI, 1992)
8081828384858687888990919293949596979899
100101102103104105
1st a
djust
2nd a
djust
Trinid
ad
3rd a
djust
Trinid
ad
Alger
ia
Alger
ia
Indones
ia
Mal
aysi
a
Indones
ia
Qatar
Badak
Niger
ia
Qatar
Abu Dhab
i
Adgas
Brunei
Austra
lia
Mal
aysi
a
Libya
Oman
% C
om
po
sit
ion
1000
1010
1020
1030
1040
1050
1060
1070
1080
1090
1100
1110
1120
1130
1140
1150
1160
1170
[BT
U/s
cf]
N2
CX
C3
C2
C1
HHV
LNG Adjustment MethodsIn-tank Blending Mix low and high-Btu LNG. Requires
inventory of low-Btu LNG
Pipeline Blending
Best when large volumes of low-Btu gas are available (Gulf Coast)
Air Injection Up to 3.8% air. Capital cost and oxygen content concerns
Nitrogen injection
Up to 2% nitrogen. Capital cost. Used by Distrigas and Cove Point.
NGL stripping Capital cost. Need market for liquids
Streaming Cargo ‘streamed’ through terminal to less-sensitive user (e.g. power)
Approaches to Interchangeability Prediction – Focus on Appliances
• Single index (Wobbe, modified Wobbe, etc.)– Incapable of describing all possible situations
• Multiple indices (AGA, Weaver, etc.)– Specific to burner type– Do not account for all fuel gases or emissions– Most common U.S. approach
• Diagrams– Do not account for all fuel gases or emissions– Attempt to combine Wobbe index with composition
parameters – Many variations and not universally accepted– Often used in Europe
Wobbe Number• Generally accepted as the best SINGLE index to
determine interchangeability• For natural gas – alkanes – heat input through
an orifice (Btu/h) at constant pressure is– proportional to heating value and– inversely proportional to the square root of specific
gravity
• Wobbe Number does not fully address interchangeability because changes in flame characteristics are not addressed
W = HHV / (sp. gr.)0.5
Interchangeability is Defined As -
The ability to substitute one gaseous fuel for another in a combustion application without materially changing operational
safety or performance and without materially increasing air pollutant emissions
Source – NGC+ Working Group on Interchangeability White Paper presented to FERC, Feb. 2005
Possible Combustion Problems With High BTU Gas
Reported Problem From
Flame lifting Excess air
Backfiring Ow excess air or low velocity
High CO Incomplete combustion
High NOx Higher flame temperature
Yellow tippingFlame lengthening from incomplete combustion
Sooting Unburned hydrocarbon buildup
Interchangeability For AppliancesThe American Experience
• AGA and USBM indices set limits for appliance fuel interchangeability
•
•
• ANSI codes are not specific for interchangeability• Interchangeability studies have been made by GTI, IGT, A.D.
Little, SoCalGas, and others– No appliance failed AGA Index or ANSI limits with LNGs– CO is most sensitive measure of performance– Some appliances have high CO with ‘hot’ LNGs
• Indices developed for older appliances do not always predict behavior of new, high-efficiency appliances
AGA Yellow tipping
Flashback
Lifting
USBM Yellow tipping Air Supply
Flashback Heat release
Lifting Incomplete combustion
Effects of Fuel Changes: Appliances and Industrial Burners
• Different appliance burners show changes in performance
• No burner exhibited a failure case of flame lifting, excessive yellow tipping, or high CO emissions
• Important performance characteristics are different for industrial burners than for residential appliances
• Industrial burners are monitored more closely but operated at more demanding conditions
Source: Gas Technology Institute
Effects of Fuel Changes: Appliances and Industrial Burners
• Industrial burners can be categorized– Some burner types, like appliances, are relatively
unaffected by changing fuel
• Burners sensitive to changing fuel include:– Burners for which flame temperature changes strongly
impact the process– Burners in high temperature processes or where
emissions are tightly regulated– Burners operating close to stability limits
• Only sensitive burner types need to be evaluated for gas interchangeability
Industrial Burners – Interchangeability Concerns
• Unlike appliances, industrial burners are complex, highly engineered, and operate under precisely controlled conditions
• Changing fuel can affect industrial burners – Performance
• Flame length, temperature, flame shape, mixing patterns, etc.
– Safety• Stability, operating range, air/fuel ratio, etc.
– Meeting regulations• Emissions of NOx, CO, etc.
• Wobbe is still best index of interchangeability
What Needs to be Learned?
Application Concern Status Need
Appliances Millions of unregulated units
Studies made, results must be compared
Testing of old, maladjusted, and new units
Commercial/ Industrial Burners
Widest range of use, efficiency, emissions
Not yet addressed
Extensive testing
Engines and Boilers
Knock, efficiency, emissions, stable combustion
Mobile engines studied, others not yet addressed
Review mobile engine data and testing
Turbines/ Microturbines
Efficiency, emissions, turbine life
New FL study planned with full-scale turbines
Collect turbine maker data and testing
Non-combustion Uses
Added process cost, plant modification
Not yet addressed
Market analysis and data collection
Work Scope• Receipt of –
– Survey of northeast industrial gas customers by SIC (or NAICS) code, engines, turbines
– Current natural gas and expected LNG ranges
• Identification of industrial burners used by specific industrial customers – largest combustion uses
• Itemizing of engines and turbines by manufacturer, model, type, and quantity
• Ranking of burners, engines, and turbines into categories – considering gas composition ranges
• Explanations provided of interchangeability reasons for placement of combustion systems into categories
Ranking Criteria• Burners and processes not expected to have any
operational, performance, or emissions concerns over the full range of specified fuel gas compositions
• Burners and processes that may have some concerns over the specified fuel gas range and may eventually need to be looked at more closely. These include– those considered to be of some concern, but likely will handle
the charges in gas composition with no difficulties– those for which insufficient information is available and may
need to be studied before making a judgment
• Burners and processes with operations, performance, or emissions concerns over at least part of the range of gas compositions. Further study would be advised for these systems before introducing a new fuel gas such as LNG.
Deliverable – Final Report
• Summary overview of industrial burners, engines, and turbines identified in survey– Number and type listed where possible– Burner types summarized by SIC codes
• Analysis of burners, engines, and turbines– General comments on impacts of proposed gas
ranges on listed combustion systems– Ranked in three classes based on changing gas
• Little or no impact expected • Some impact expected or too little information available to
decide about impacts• Impacts expected and more detailed study of combustion
systems recommended
Cost and Schedule
• Cost– Project cost - $69,000– Includes initial and final trips to meet with sponsors
• Schedule– Work planned from June 15, 2006 through August 15,
2006– GTI will start work immediately with partial survey
results– Work completion is dependent on completed
Northeast Stakeholders Group surveys– Work can be slowed if all survey results are not
available
Classification of Industrial Burners
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
GTI Proprietary & Confidential
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
• Diffusion Mixed– Non-Staged– Air Staged– Fuel Staged
• Partial Pre-mixed– Non-Staged– Air Staged
• Pre-Mixed– Non-Staged
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
• Gas• Liquid• Solid• Dual
Classification Criteria
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
• Air• Oxygen• Oxygen Enriched Air• Preheated Air
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
• Forced Draft• Natural Draft• Inspirated• Aspirated
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
• Direct• Indirect
1. Mixing Type
2. Fuel Type
3. Oxidizer Type
4. Draft Type
5. Heating Type
6. Burner Geometry
Classification Criteria
• Round Nozzle• Rectangular Nozzle• Swirl
Burner Types
1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Radiant Wall• Thermal Radiation• Radiant Tube
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Radiant Wall– Natural Draft– Forced Draft
• Pre-mixed• Non-Premixed
• Thermal Radiation• Radiant Tube
Burner Types
1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Radiant Wall• Thermal Radiation
– Porous Ceramic
– Ported Ceramic
– Fiber Metal
– Flame Impingement
– Catalytic
– Perforated Ceramic
– Porous Refractory
– Wire Mesh
• Radiant Tube
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Radiant Wall• Thermal Radiation• Radiant Tube
– Non-Circulating– Recirculating– Forced Draft– Inspirating
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Pre-mixed• Diffusion Mixed• Partially Pre-mixed• Air Staged
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• One Box• Two Box• Rotary / Heat
Wheel• Radiant Tube
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Round Flame• Wall Fired Flat
Flame• Radiant Wall• Flat Flame
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Low NOx• Ultra Low NOx• Conventional
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Low NOx– External Flue Gas
Recirculation (EFGR)– Air Staged– Fuel Staged– Fuel Induced Recirculation
• Ultra Low NOx• Conventional
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Low NOx• Ultra Low NOx
– Pre-mixed– Partially Premixed– Rapid Mix– Internal Flue Gas
Recirculation
• Conventional
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Low NOx• Ultra Low NOx• Conventional
– Swirl– Register
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Duct– Linear Grid– Grid
• Make-up Air
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Air-Oxy Fuel– Concentric Pipe– Multiple Nozzle– Flat Flame– Staged
• Oxy-Fuel– Polishing– Forehearth
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Single Point– Non Assisted
– Simple Steam Assisted
– Advanced Steam Assisted
– Low Pressure Air Assisted
• Multi-point• Enclosed
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Single Point• Multi-point
– Non Assisted
– Simple Steam Assisted
– Advanced Steam Assisted
– Low Pressure Air Assisted
• Enclosed
Burner Types1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Single Point• Multi-point• Enclosed
– Non Assisted– Simple Steam Assisted– Advanced Steam Assisted– Low Pressure Air Assisted
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Thermal Radiation– Drying – Plastic
thermoforming– Paint curing
• Radiant Tube– Indirect heating
• Radiant Wall– Process Industry
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Metals Industry• Ceramic/Glass
Industry
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Zinc Distillation • Metals Industry • Glass Industry
Burner Applications
1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Chemical and Hydrocarbon Process Industries
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Steam Generation• Water Heating• Space Heating
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Space Heating• Turbine Exhaust• Uniform Spread
Heating
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners
• Metal Heating• Metal Melting• Glass Melting• Mineral Calcining
Burner Applications1. Radiant Burners
2. High Velocity Burners
3. Regenerative Burners
4. Natural Draft Burners
5. Boiler Burners
6. Linear Grid / In-Duct Burners
7. Oxygen Enhanced / Oxy-Fuel Burners
8. Flare Burners • Petrochemical Industries