Interchangeability Issues and Status of NGC Activities

1
Industry Perspective on Gas Interchangeability
and Gas Quality

• Interchangeability Issues and Status of NGC
  Activities

Ted A. Williams Codes, Standards Technical
Support American Gas Association
2
Gas Quality Issue Areas

• Hydrocarbon Liquid Dropout Hydrocarbon Dew
  Points Impacts Throughout Gas Transportation
  System
• Gas Interchangeability End Use Implications
  Including Combustion and Non-Combustion
  Applications

3
Contemporary Drivers for Interchangeability

• Imported LNG
• Federal Energy Regulatory Commission Involvement
• NGC Formation of NGC Steering Committee and Gas
  Interchangeability Task Group 2-4/2004
• Task Group Reporting to NGC 2/2005
• Stakeholder Comments to FERC 4/2005
• FERC Technical Conference 5/17/05
• New Stakeholders and Information Needs
• SAFETY OF GAS CONSUMERS

4
NGC Gas Interchangeability Task Group -
Stakeholders Represented

• Producers and Suppliers
• Processors
• Pipelines
• LDCs
• Direct Connect Customers
• Gas Consumers

5
Process Used by Technical Work Group

• Reviewed Classical Interchangeability Studies in
  U. S.
• Over 60 Years of Experience
• Attempted to Gather Experience Gained Throughout
  the World
• Defined Constraints in End Use
• Reviewed Historical Characterization Data and
  Collected New Data
• Identified Gaps in Knowledge and Technology
• Drafted White Paper and Supporting Appendices
• Worked to Define a Process for Establishing
  Limits
• Worked to Reach Consensus on Limits

6
General End Use Considerations

• Technical Limits of Performance of End Use
  Technologies
• Practical Limits of Responding to Changes in Gas
  Compositions
• Rates and Frequencies of Compositional Changes
• Attended versus Non-Attended Operation
• Adjustability versus Retrofit
• Economic Efficiencies in Responding to Changes
• Consistencies/Inconsistencies in Gas
  Compositional Requirements
• Technical Justification of Requirements

7
Conclusions on Consideration of Limits

• Heating Value Alone is not Sufficient
• Wobbe is the Most Robust Parameter
• However, Wobbe Alone is not Sufficient
• Multiple Parameters Required for Complete
  Definition of Requirements

8
Interim Gas Interchangeability Guidelines
Natural Gas End Use

• A. A Range of plus and minus 4 Wobbe Number
  Variation from Local Historical Average Gas /-4
  or, alternatively, Established Adjustment or
  Target Gas for the Service Territory
• Subject to
• Max. Wobbe Number Limit 1,400
• Max. Heating Value Limit 1,100 Btu/scf
• B. Additional Composition Maximum Limits
• Max. Butanes Limit 1.5 mole percent
• Max. Total Inerts 4 mole percent
• C. EXCEPTION Service territories with
  demonstrated experience with supplies exceeding
  these Wobbe, Heating Value and/or Composition
  Limits may continue to use supplies conforming to
  this experience as long as it does not unduly
  contribute to safety and utilization problems of
  end use equipment. (Demonstrated Experience
  refers to actual end use experience established
  by end use testing and monitoring programs.)

9
Application of Interim Guidelines

• Interim Guidelines to Apply in Short Term
• Additional Technical Data are Needed on
  Acceptable Equipment Limits
• Additional Research is Needed on Specific End-Use
  Applications and Equipment Types
• The Ultimate Goal is to Develop Long-Term
  Guidelines Within Three Years
• Implementation of Guidelines Upstream of End
  Users is a Policy Issue Outside the Scope of the
  Task Force

10
Technical Gaps Requiring Additional Research

• Appliances
• Industrial Commercial Burners
• Turbines, Micro-Turbines Power Burners
• Stationary Vehicle Engines
• Non-Combustion Feedstock Applications

11
Appliance Issues Three Examples

• Sensitive Appliances
• New Burner Technologies
• High Efficiency
• Low Emissions
• Low Secondary Air Designs
• Fully Premix
• FVIR Technologies
• Misadjusted Appliances
• Risks Due to Supply Changes
• Correlation of Misadjustment to Failure Modes
  (e.g., CO generation)
• Durability of Appliance Components