Utilization of New Gas Supplies Filling Key Information Gaps Gas Interchangeability and Quality Forum November 19-20, 2008 Washington, DC Charles Benson ENVIRON International Corp. 8 Hollis Street Groton, MA 01450 cbenson@environcorp.com 978-448-8591
Introduction Developing Natural Gas Interchangeability Guidelines Valid interchangeability indices and relevant equipment performance data are needed to apply sound gas quality guidelines. Screening Workshop Assessment Monitoring Conduct screening assessment of interchangeability issues. Characterize current and historical gas supplies. Identify potentially sensitive end-use applications. Conduct interchangeability index analyses. Hold workshop with stakeholders. Provide common understanding of interchangeability issues. Collect historical information on LDC operations. Gather inputs from end-users. Conduct assessment of interchangeability requirements and accommodation strategies. Test sensitive equipment, in the laboratory or in the field. Define gas composition guidelines and any necessary equipment adjustments. Monitor performance of representative equipment during initial introduction of new gas supply.
Topics for Discussion 1 2 3 Interchangeability Indices Residential Appliance Performance Commercial & Industrial NO x Emissions
Interchangeability Indices Impacts on Combustion Equipment The introduction of new gas supplies may impact the performance of certain combustion equipment. Higher Wobbe number gas may have the following impacts: Energy input (firing rate) may increase. Excess air level may decrease. Carbon monoxide (CO) emissions may increase. Yellow tipping (soot generation in flame) may increase. NO x emissions may change. Heat exchanger temperatures may rise. Lower Wobbe number gases generally have the opposite effect. However Flame lifting may increase. Carbon monoxide emissions may increase. Interchangeability indices (equations based on gas properties and compositions) have been developed to characterize many of these impacts. Wobbe number AGA indices Weaver indices
Interchangeability Indices AGA Task Group An AGA Task Group is currently addressing gas interchangeability analysis methods. The Task Group, led by Rosemarie Halchuk of Xcel Energy, includes 47 members representing,,, LDCs Pipelines Trade organizations/consultants Manufacturers LNG suppliers This group is addressing technical aspects of interchangeability. It s mission is to coordinate and conduct research related to gas interchangeability and end-use applications. The group s initial activities are focusing on possible revisions to the AGA Bulletin 36 and Weaver interchangeability calculation methods for residential appliances. Consider new appliance burner designs. Incorporate latest combustion science.
Topics for Discussion 1 2 3 Interchangeability Indices Residential Appliance Performance Commercial & Industrial NO x Emissions
Field Testing of Appliances CO Emissions Residential appliance field testing can characterize the sensitivity of an entire population to gas composition changes. Impact of LNG on Residential Appliance Performance 1 0.9 Domestic 1090 LNG 1345 Wobbe 1400 Wobbe 0.8 0.7 Fraction of Appliances 0.6 0.5 0.4 0.3 0.2 Field Data for Residential Appliances 0.1 0 0-200 200-400 400-600 600-800 800-1000 1000-1200 1200-1400 1400-1600 1600-1800 1800-2000+ Carbon Monoxide Emissions (ppm, air-free)
Laboratory Testing of Appliances CO Emissions Laboratory testing can provide detailed information on gas composition impacts as well as equipment adjustment options. 1000 Air-Free CO (ppmv) 900 800 700 600 500 400 300 200 100 Derated On Not Over-fired Derated ANSI Limit (400 ppmv) Residential Boiler Test Data 0 1100 1150 1200 1250 1300 1350 1400 1450 Wobbe Number
Laboratory Testing of Appliances Lifting, Yellow Tipping Laboratory testing can quantify the impact of gas composition changes on flame lifting and soot production (yellow tipping). Increasing Wobbe -4 0 +4
NYSEARCH/NGA Interchangeability Project Overview In a NYSEARCH/NGA project, we are evaluating the impact of changing gas supplies on the performance of in-service residential appliances. The ability of in-place appliances to operate properly with gas supply changes is not sufficiently understood. very wide range of appliance types and ages. installation and adjustment variability. In the project, we are documenting information and defining testing procedures that will fill information gaps regarding natural gas interchangeability for in-place appliances. conducting field testing to determine the performance of in-place appliances and the potential sensitivity of the population to gas composition changes. The project team includes NYSEARCH, ENVIRON, GTI, and fifteen local natural gas distribution (LDC) and pipeline companies.
NYSEARCH/NGA Interchangeability Project Phases The project is being carried out in field assessment and laboratory testing phases. In Phase 1 (2008-2009) we are.. Developing a database of appliance types. Identifying potentially sensitive appliance types. Conducting field testing of 3200-3600 appliances located in four LDC service areas. Evaluating the performance of the appliance population. Planning Phase 2 activities. In Phase 2 we may Conduct laboratory test of new and used appliances, focusing on sensitive models and common maladjustments. Develop guidelines for accommodating changing gas compositions. Determine the most effective interchangeability indices for in-service appliances.
Topics for Discussion 1 2 3 Interchangeability Indices Residential Appliance Performance Commercial & Industrial NO x Emissions
Commercial & Industrial NO x Emissions Overview The introduction of imported LNG into California has focused recent industry efforts on the characterization of NO x emissions changes. For combustion of natural gas, NO x emissions (NO + NO 2 ) are formed primarily through the thermal mechanism. NO x levels increase exponentially with flame temperature. The adiabatic flame temperature for combustion of imported LNG is only very slightly higher than that for domestic natural gas. 1332 Wobbe domestic natural gas = 3533 F 1385 Wobbe imported LNG = 3542 F Combustion kinetic calculations show that similar NO x emissions will be produced if equipment is operated at the same level of excess air. 1332 Wobbe domestic natural gas = 20 ppm NO x 1385 Wobbe imported LNG = 21 ppm NO x The level of increase or decrease in NO x emissions is expected to be small and will depend primarily upon the burner type and any changes in excess air level.
Commercial & Industrial NO x Emissions Equipment Tuning Commercial and industrial equipment can be tuned to offset any increases in NO x emissions. + 4% Wobbe Baseline Gas - 4% Wobbe 50 45 40 NO x (ppm, 3%O 2 ) 35 30 25 20 15 10 5 Commercial Boiler Burner Test Data 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 Exhaust O 2 (%, dry)
Conclusions Information developed through these projects will facilitate the successful distribution of new and changing gas supplies. Laboratory and field performance data will enable LDCs to work more effectively with their customers to successfully accommodate a wider range of gas compositions. Equipment tuning strategies will reduce or eliminate environmental impacts associated with gas composition changes. Improved interchangeability analysis methods could reduce or eliminate the need for equipment testing. provide a higher level of confidence in proposed gas quality guidelines.