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	Wobbe number (Site not responding. Last check: 2007-10-23)
		The Wobbe number, or Wobbe index, of a fuel gas is found by dividing the high heating value of the gas in Btu per standard cubic foot (scf) by the square root of its specific gravity with respect to air.
		Occasionally Wobbe numbers are calculated on the basis of megajoules per cubic meter instead of Btu per scf; that this is being done is usually obvious from the great difference in the values.
		For example, using SI units the Wobbe number for methane is 50.7.
	www.sizes.com /units/wobbe_number.htm (242 words)

	Control Systems engineering - BTU/Pressure Swing Control
		The Wobbe Index as saved from one of the manufacturers is the ratio of the heat of combustion of a gas to its specific gravity.
		The Wobbe Index is the number obtained by dividing the saturated heating value of the gas by the square root of its specific gravity.
		Wobbe index is a measure of the amount of heat released by a gas burner of constant orifice.
	www.eng-tips.com /viewthread.cfm?qid=119863&page=3 (494 words)

	Apparatus for measuring a gas value - Patent 6047589
		The measured attenuation is used to derive the calorific value and/or Wobbe index of the gas.
		This invention relates to apparatus for measuring a gas value, and in particular co apparatus for measuring the calorific value and/or the Wobbe index of combustible fuel gas, and it also relates to apparatus for measuring the amount of energy provided when in the form of combustible fuel gas.
		The control means 56 can use the volumetric flow rate and the value of the calorific value and/or Wobbe index in a calculation or process to derive the amount of energy supplied by provision of the fuel gas; the energy becoming sensible heat when the gas is burned.
	www.freepatentsonline.com /6047589.html (2315 words)

	Measurement of a gas characteristic - Patent 5635626
		Apparatus to measure the calorific value and/or the Wobbe index of fuel gas supplied along a pipe.
		The gas characteristic(s) concerned is/are the calorific value and/or the Wobbe index of a fuel gas.
		Apparatus to measure the calorific value and/or the Wobbe index of the fuel gas is indicated at 4.
	www.freepatentsonline.com /5635626.html (1299 words)

	Chemical plant design & operations - Nitrogen injection in natural gas for Wobbe Index control.
		Similar to the issue of injecting N2 in LNG, is one of maintaining Wobbe Index of natural gas.
		The volume flow through an orifice is basically related to the formula for velocity pressure in the hole and the heat release of the eventual flame is the calorific value x the volumetric flow.
		The problem with Wobbe number is that it doesn't entirely take account of the reactive nature of the component gases in the mixture and so the flame speeds of supposedly similar mixtures can be somewhat different.
	www.eng-tips.com /viewthread.cfm?qid=143457&page=1 (876 words)

	AQMD Sues PUC to Protect Public Health and Prevent Increased Air Pollution from "Hot Gas"
		The Wobbe Index is a technical specification that refers to the heating value of a fuel gas; the higher the number, the higher the heating value.
		AQMD also called for expedited research into the air quality impacts associated with burning a higher Wobbe Index gas and the cost effectiveness of lowering the heating value of imported gas before a natural gas standard was adopted.
		Had the commission adopted AQMD’s recommended Wobbe Index limit of 1360, hot gas still could be imported from overseas as long as it was treated to meet the standard before being shipped to customers.
	www.aqmd.gov /news1/2007/HotGasPR.html (894 words)

	[No title] (Site not responding. Last check: 2007-10-23)
		The single most useful combustion property of natural gas is the Wobbe index or Wobbe number, as it is a measure of how a gas will burn.
		As Wobbe number increases, the rate of energy delivered to a burner increases until a point where there is insufficient time and oxygen for complete combustion to occur.
		Gas must be treated to ensure that the Wobbe index is maintained within an optimal range for combustion.
	www.chemsystems.com /newsletters/perp/May06_N04S8.cfm (2141 words)

	AMS Analysen-, Mess-, Systemtechnik
		The probe gas is completly oxidised in air surplus, the residual Oxygen is a reliable measure for the Air Demand of the probe gas whwn oxidised.
		Herewith the determination of the Wobbe Index is based on the measuring of just one single parameter, the residual Oxygen concentration, after the oxidation of the probe gas.
		Parallel to the Wobbe Index determination the Specific Gravity of the probe gas is determined from the measurement of the Oxygen concentration in the already mixed (with combustion air) but not yet burned probe gas.
	www.ams-dielheim.com /english/neuigkeiten.html (496 words)

	Gas Quality: 5 Jun 2003: Written Ministerial Statements (TheyWorkForYou.com)
		The Wobbe Number represents a measure of the heat release when a gas is burned at constant gas supply pressure.
		High Wobbe gas requires more oxygen to burn completely; and there is a risk that some of the older gas appliances may not be able to draw in sufficient oxygen to work safely.
		The alternative option would be to retain the current Wobbe limit—avoiding the need to identify/remove certain gas appliances, but with a penalty in terms of gas import costs, and ease and reliability of access to an increasingly global and liquid international gas market.
	www.theyworkforyou.com /wms/?id=2003-06-05.30WS.4 (725 words)

	EPSA: FERC Filings (Site not responding. Last check: 2007-10-23)
		While EPSA agrees with the NGSA suggestions regarding which elements should be included in pipeline tariffs, the NGC+ white paper suggests that the Wobbe Index number have a range — this is an important deliverability specification that must be included in pipeline tariff.
		While 1400 is a reasonable Wobbe limit, pipelines need to determine a Wobbe value based on historical data with the obligation to deliver gas within +/- 4 percent of that number.
		Therefore, EPSA recommends that the Commission retain the white paper’s suggested +/- 4 percent Wobbe index range relative to the local average in a proposed rulemaking.
	www.epsa.org /forms/documents/ArticleFormPublic/viewArticle?id=452700000039 (1061 words)

	Gaseous Fuels
		Area and pressure drop remain the same) the new heat release rate may be calculated as the ratio of the CV multiplied by the square root of density.
		If the Wobbe number and flame speed factor are identical for two gases they are completely interchangeable.
		This is termed the Wobbe Index and determines the interchangeability of gases.
	eyrie.shef.ac.uk /will/eee/cpe630/comfun5.html (3558 words)

	Pipeline and Gas Technology - Construction \| Operations \| Maintenance \| Management
		The Wobbe Index is thus an indication of energy flow in the system at the same gas pressures and pressure drops.
		A standard fuel system may for example be designed for a Wobbe Index of 1220 ±10% Btu/scf (48,031 ±10% kJ/ Nm3) based on the LHV of the fuel.
		The Wobbe Index and BTU content are therefore higher than for typical pipeline quality gas, but the dew point is usually lower.
	www.pipelineandgastechnology.com /0106gasmachinery.kurz.html (2678 words)

	Xytek - Analyzer Control Systems (Site not responding. Last check: 2007-10-23)
		The Wobbe Index is a measure for the needed oxigen that a fuel (gas) needs for optimal combustion.
		The Wobbe Index is calculated on base of measurements of the remaining oxigen after cathalytical combustion of the gas.
		Two or four(optional) analog outputs are available for the Wobbe Index (WI), Calorific Value (CV), SG and the Combustion Air Requirement Index (CARI).
	www.xytek-nl.com /wim3100.htm (272 words)

	GAMAzine: New Gas Supplies Will Affect Appliance Service - Feature Article - Air Conditioning, Heating & Refrigeration ... (Site not responding. Last check: 2007-10-23)
		The usefulness of the Wobbe number is that for any given orifice, all gas mixtures that have the same Wobbe number will deliver the same amount of energy.
		The Wobbe number (or Wobbe index) of a fuel gas is found by dividing the higher heating value of the gas in Btu per standard cubic foot (scf) by the square root of its specific gravity with respect to air.
		The Wobbe numbers of natural gas piped to most homes in the United States range from 1,310 to 1,390, although in any one area of the country it will not fluctuate widely around an historical average that is between those two extremes, Stanonik pointed out.
	www.achrnews.com /CDA/Articles/Feature_Article/f0178b8ea806a010VgnVCM100000f932a8c0____ (1284 words)

	LNG: Florida Decision Could Impact Gas Quality Nationwide
		Florida Gas Transmission Co tightens the Wobbe Index range for LNG imports and sets a precedent for taking a regional approach to gas quality standards.
		While the incremental costs associated with Wobbe modification facilities such as nitrogen injection and LPG extraction are not insignificant, they pale in comparison with those associated with the unloading, storage and vaporization of LNG.
		The Wobbe Index at Elba is already effectively capped at 1,396, the theoretical limit imposed by the terminal’s restrictive heating value specification of 1,075 Btu/scf (see LNGWM, Sep ’05).
	www.poten.com /show_articles.asp?id=525&table=tmarket (1025 words)

	Wobbe index - Wikipedia, the free encyclopedia
		[edit] Wobbe Index (kcal per standard cubic meter) of common fuel gases
		Fuel Gas Upper Index Lower Index Hydrogen 11,528 9,715 Methane 12,735 11,452 Ethane 16,298 14,931 Ethylene 15,253 14,344 Natural gas 12,837 11,597 Propane 19,376 17,817 Propylene 18,413 17,180 n-butane 22,066 20,336 Iso-butane 21,980 20,247 Butylene-1 21,142 19,728 LPG 20,755 19,106 Acetylene 14,655 14,141 Carbon monoxide 3,060 3,060
		Family Wobbe Index range (MJ/Sm3) Type of gas 1 22.5 – 30 Town gas / Syn Gas 2 L 39 – 45 Natural H 45.5 – 55 3 73.5 – 87.5 LPG
	en.wikipedia.org /wiki/Wobbe_index (392 words)

	Measuring Up - Science - RedOrbit
		The technical specifications most germane to the debate are the Wobbe index and cricondentherm hydrocarbon dew point (CHDP).The Wobbe index indicates the burning characteristics of natural gas and its utilization in end-use applications.
		In some cases we could be talking in dollar terms in hundreds of thousands in damages or settlements...." Strawn says he would like to see a rulemaking from FERC and says the Wobbe index would be a legitimate starting point, "while there's still some debate whether it addresses all of our concerns.
		What we would say is it needs to be addressed on a pipeline-by-pipeline basis." Lewis maintains that pipelines and their customers need to sit down and establish a historical Wobbe index, then allow for a variance from that of plus or minus 4%.
	www.redorbit.com /news/science/246714/measuring_up/index.html (1949 words)

	Responding to Climate Change 2006 - Research & Technology - Research
		Recent results from our laboratory show that, in the Netherlands, a maximum of 5% H2 may be present in the natural gas for the household market, and still guarantee the performance of domestic appliances.
		The results also show that the wider the range of Wobbe Index of the distributed gas, the more hydrogen can be accepted.
		One caveat is that the maximum hydrogen concentration can only be realized at the maximum of the Wobbe range, and decreases with decreasing Wobbe Index.
	www.rtcc.org /2006/html/res_tech_res_gasunie.html (776 words)

	Re: Wobbe index influence (Site not responding. Last check: 2007-10-23)
		A Wobbe index on any burner (application of boiler or gas turbine or others) means that the burner is set-up to burn fuels with that Wobbe number.
		When the fuel has near the same Wobbe number then little or no set-up to the air to fuel ratio is required.
		So, this mean is the burner is set up for wobbe index number of 1350, then most natural gas in the US, with minor adjustments, is acceptable to the burner; however, the unit will require larger fuel to air adjustments when using Libya natural gas.
	www.steamforum.com /_discstm/000011e5.htm (184 words)

	Algas SDI: World Class Liquid Vaporizers & Gas Mixing Solutions
		Precision instrument used in feed control and gas blending where continuous measurement of the gas heating value is required.
		The GA500™ burns a sample of the LPG/Air mixture to provide an accurate measurement of the Wobbe Index.
		The Calorific Value is accurately calculated and displayed from the Wobbe Index and specific gravity.
	www.algas-sdi.com /accessories.html (380 words)

	Power Engineering - Handle With Care
		The Modified Wobbe Index is the ratio of the lower heating value to the square root of the product of the specific gravity and the absolute gas temperature.
		Variations in the Modified Wobbe Index of only ±3 percent are believed by many GT specialists to cause serious trouble.
		In addition to variations by region, there can be significant variations in Wobbe Index for an individual power plant purchasing its gas from different pipeline suppliers, as corporate fuel managers try to exploit daily or weekly changes in gas price.
	pepei.pennnet.com /Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=242393&VERSION_NUM=2&p=6 (4204 words)

	Alternate Energy Systems
		From this data, Heating Value (CV) and Wobbe Index Number (WI) are calculated and displayed.
		Specific Gravity, Wobbe Index, and Calorific Value are displayed simultaneously.
		During initial setup, the display unit is also used for the input of setpoint data and the input of the properties of the liquid LPG.
	www.graviblend.com /OpConcept.htm (982 words)

	ISO 6976 Natural Gas - Calculation of Calorific Values, Density, and Relative Density and Wobbe Index from Composition ...
		This International Standard specifies methods for the calculation of the superior calorific value, inferior calorific value, density, relative density and Wobbe index of dry natural gases, natural gas substitutes and other combustible gaseous fuels, when the composition of the gas by mole fraction is known.
		The methods provide a means of calculating the properties of the gas mixture at commonly used metric reference conditions.
		The term "heating value" is synonymous with "calorific value"; "specific gravity" is synonymous with "relative density"; "Wobbe number" is synonymous with "Wobbe index"; "compressibility factor" is synonymous with "compression factor".
	engineers.ihs.com /document/abstract/FRWNCAAAAAAAAAAA (642 words)

	Gas Technology: A Burning Issue - Feature Articles - Appliance Design
		The Wobbe Index is the main indicator of the interchangeability of gases (see sidebar).
		Historically, natural gas in the U.S. had a Wobbe number in the range of 1,200 to 1,400, with an average of about 1,345 and a heating value of 1,035 BTU per cu.
		A pipeline gas stream rated at 1,075 BTU per scf and with specific gravity of 0.65 (a general rule-of thumb for pipeline gas), would have a Wobbe Index of 1,333 BTU/scf.
	www.appliancedesign.com /CDA/Articles/Feature_Article/3f525cf0a068e010VgnVCM100000f932a8c0____ (1686 words)

	LNG Observer - New process to help terminals handle rich LNG
		Europe’s gas pipeline distribution systems have similar specifications in the form of a Wobbe Index that pose similar problems for hot LNG supplies.
		AMEC Paragon Inc. and Pi Technology Associates Inc. have developed a new process for recovering ethane and heavier hydrocarbons (NGL) from LNG that can be used to reduce and control the HHV (or Wobbe Index) of the resulting sendout gas as required to meet pipeline quality specifications.
		The new process is designed with operational flexibility to adjust and control NGL recovery from such hot LNG as required to yield sendout gas compliant with pipeline quality specifications of HHV or Wobbe Index.
	www.ogj.com /Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=245394&VERSION_NUM=2&p=94 (2151 words)

	Wobbe Index and Fuel Gases
		The Wobbe Index is a number indicating the interchange ability of fuel gases.
		The Wobbe index relates fuel gas heating characteristics in a manner that is useful for blending fuel gases, or to obtain a constant heat flow from a gas of varying composition.
		The Wobbe Index does not relate flame temperature, heat transfer coefficients or temperature gradients.
	www.engineeringtoolbox.com /wobbe-index-d_421.html (245 words)

	CPUC - Proceeding R0401025
		Cushnie said that if the Commission were to adopt President Peevey's alternate, it should be amended to incorporate Calpine Corporation's proposed Wobbe index rate-of-change limitation of two percent per minute.
		Leslie stated that the evidence in the case supports a maximum Wobbe Index of 1400.
		Milner explained, however, that the AD¿s proposed 1385 maximum Wobbe Index is acceptable to Shell Trading.
	www.cpuc.ca.gov /PUBLISHED/proceedings/R0401025.htm (2682 words)

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