Wobbe index is defined as hhv vgas specific gravity relative to air and is often more stringent than the heating value specification. Wobbe index is calculated from heating value and specific density, according iso en 69762005. The results are based on giignl 20 average lng composition data, with mwm 11 calculation method for methane number. Jun 09, 2017 wobbe index wi of a gas normally natural gas is the indication of the heating value of the gas from the pipeline at the orifice where a burner is located, this could be a gas turbine or a boiler. The feed system includes structure for supplying the first gas mixture to the mixing chamber via a first number of openings, structure for supplying an. Sep 15, 2018 wobbe index is an indicator of the interchangeability of fuel gases whereas calorific value is the total amount of heat energy that a unit mass of fuel can produce when we burn it completely. In one embodiment, the wobbe index of the low wobbe index fuel 11a is increased by mixing a component 22 with a high wobbe index into the low wobbe index fuel 11a to produce a blend 25, and the blend 25 has a wobbe index that falls within a desired range 26. Wi hhv sg12 1 where wi wobbe index btuft3 hhv high heating value btuft3. Within operational ranges corresponding to the permissible wobbe index namely, primary air coefficients and heat inputsthe equivalence. Reported fuel effects on no x fullscale engine testing confirms rig testing that, without burner modifications or engine control enhancements, increasing wobbe index can result in increased no x. Document label definitions symbol label description warning.
The wobbe number is representative of the fuel energy input rate to combustion equipment when the gas supply pressure is held constant as. Wobbe index is a measure of the quality of fuel such as ignition and combustion properties in sparkignition engines it is a critical gas quality parameter for gaseousfueled engines. Wobbe index and gross calorific value in european networks analysis of ranges and variability 1. Device for determining the wobbe index of a gas mixture 19930608 19930608. Blending fuel gas to optimize use of off spec natural gas. The basis for the wobbe index is if two fuel gases have identical wobbe numbers, they will deliver the same amount of heat. Its portfolio ranges from dew point measurement solutions, analytical laboratory equipment, nmr technology, wobbe and btu analyzers. For example in belgium, the legally acceptable wobbe index limits, as given by a royal decree, lie between 14.
Wobbe index is used to compare the combustion energy output with different composition of fuel gases. Wobbe index is an important parameter to evaluate gaseous fuel interchangeability 35 37, and the definition is given by eq. Gas interchangeability study and resulting nysearch. The wobbe index wi of hgas as supplied in most regions in europe has a variation range peak to peak value lower than 3 mjm. The wobbe index and natural gas interchangeability emerson. The effects of hydrogen on wobbe index joint cenentsog workshop on wobbe index and gross calorific value in the european gas value chain 28th september 2017 jose a. The wobbe index in the hgas standard and how to include. Therefore, this is the key difference between wobbe index and calorific value. Such improved systems and methods may ensure adequate modified wobbe index control and, hence, adequate overall system performance without requiring complex feedback mechanism and the like. Equipment is rated to operate over a specified wobbe index range and, in some cases, provides an adjustment that corresponds to the wobbe index. Experimental study of the influence of natural gas. It gives an indication of whether a turbine or burner will be able to run on an alternative fuel source without tuning or physical modifications. The equation for calculating wobbe index is as follows. Cosa xentaur combines the strength of over 30 years of cosa instruments sales, service and application support and experience with xentaur corporations innovative measurement solutions.
Background as a continuation of mandate m400 and supported by the conclusions of the 29th madrid forum, cen continues working on finding an eu agreement for a wobbe index band, including elaborating on the possibility of regional bands. Difference between wobbe index and calorific value compare. Device for determining the wobbe index of a gas mixture. Automatic wobbe index control for peak shaving plants wobbe index wobbe index explanation from american gas association bulletin no. The wobbe index wi or wobbe number is an indicator of the interchangeability of fuel gases such as natural gas, liquefied petroleum gas lpg, and town gas and is frequently defined in the specifications of gas supply and transport utilities if is the higher heating value, or higher calorific value, and is the specific gravity, the wobbe index, is defined as. Sample line, engineered to guarantee the best representativeness of the process gas and fastest analysis time. The wobbe index is a method of expressing the energy content of a fuel by taking into account its density with respect to the density of air, which is better known as its specific gravity. The current national legislation allows import with wobbe index down to approx. Position paper on the impact of including methane number in. Reported fuel effects on no x fullscale engine testing confirms rig testing that, without burner modifications or engine control enhancements, increasing wobbe index.
Conditioning system, engineered and made in accordance to any different process plant with different. The most important combustion parameters are wobbe index, methane number and laminar flame speed. Rate of change of wi is identified as a significant issue. In many countries in recent times there has been a significant shift from a single source of indigenous natural gas towards multiple sources of gas from new interconnector pipelines and shipped lng. The energy input is a linear function of wobbe index.
Us5482679a device for determining the wobbe index of a. Nov 05, 2020 the wobbe index is sometimes called the interchangeability factor symbol, wn or wi. Upon entering the cva100, the sample flow encounters a tee and is split between the fast loop and the sample loop. The analyzer is a calorimeter that burns a sample to measure the oxygen content in flare gas and calculate the wobbe index. Us5482679a device for determining the wobbe index of a gas. Technical data for propane, butane, and other lpg mixes. Hereby a gas mantle is heated and the temperature is measured. B unless otherwise authorized by the commission, a wobbe index for a distinguishable distribution area that deviates more than 4% from the established wobbe index is considered a change in service. The wobbe index wi or wobbe number is an indicator of the interchangeability of fuel gases such as natural gas, liquefied petroleum gas. The wobbe index was defined 1927 by the engineer goffredo wobbe.
Hobre wim wobbe index meter installation, operation and. The prominent reference 8 expects that this range will remain so in the midterm future. The wobbe index the wobbe index wi is an important gas quality indicator for most gasburning equipment. Domestic customers case for change dr martin brown, principal specialist, dnv gl widening the wobbe index. Hydrogen reduces wobbe index and calorific value of natural gas when mixed with it reduction depends on natural gas composition not only wigcv is affected acceptable concentrations of hydrogen are different today for different end uses many consequences of hydrogen admixtures are qualitatively rather similar to gas natural fluctuations. An additional co 2 measurement allows the determination of mean molar mass and specific density of the sample probe. Regardless of calorific value, gases with the same w produce the same heat load in a gas burner. The burner thermal load is directly related to the wobbe index of the fuel gas 2. The higher heating value is used to calculate wobbe numbersaka wobbe index wi.
The wobbe index in the hgas standard and renewable gases in. Implementation of the wobbe index proposal as part of the cen standard en 16726. A measure of the degree to which the combustion characteristics of one gas resemble those of another gas. However, in a presentation from 2010 the local gas supplier distrigas admits that industry cannot accept a wobbe index variation. This is important in considering the energy efficiency of gasfired equipment. Technical paper on lpg vaporizers and lpgair mixing systems.
This document specifies methods for the calculation of gross calorific value, net calorific value, density, relative density, gross wobbe index and net wobbe index of natural gases, natural gas substitutes and other combustible gaseous fuels, when the composition of the gas by mole fraction is known. In many countries in recent times there has been a significant shift from a single source of indigenous natural gas towards multiple sources of. So this tool was designed for free download documents from the internet. Automatic wobbe index control for peak shaving plants. Variability in the wi will however result in power output variations of the gas application and also. This will involve providing documentary evidence, procedures, and any safety. Consists of conditions, practices, or procedures that must be observed to prevent personal. If the wi of a fuel gas is constant, the fuel energy supply to the gas application is constant for a given supply pressure and temperature, notwithstanding composition variations of the gas. Us8459033b2 systems and methods for modified wobbe index. The ratio of the gross heating value of a gas to the square root of the relative density of the gas, wi hv v rd. Difference between wobbe index and calorific value. Flare monitoring regulatory compliance and analyzers.
British standard 7859 provides all the details on standard conditions, component heating values, ideal vs. About us we believe everything in the internet must be free. The wobbe number is named for the italian engineer goffredo wobbe, who in 1926 published a paper. Wobbe index and each change in service with the date of its related customer notification. Wobbe index for common fuel gases propane, butane, methane and more sponsored links the wobbe index indicates the interchange ability of a fuel gas and is the best indicator of similarity between natural gas and a specific propaneair mixture. Device for determining the wobbe index of a first gas mixture, including a wobbe index meter having a mixing chamber, and a feed system for supplying a first gas mixture and an oxidation gas to the mixing chamber of the wobbe index meter. There is therefore a desire for improved systems and methods for adequate modifying wobbe index control without the complexity and expense of known systems. The wobbe index is a measure of the interchangeability of fuel gases and their relative ability to deliver energy. Gas engines have in general no difficulty with respect to. Conversion factors, lpg properties, wobbe index and compatible mixtures, etc.
Pdf from natural gas to hydrogen via the wobbe index. Also wobbe index is defined as wi cvsqrt rd the conclusion is therefore that. Figure 3 shows the relationship between wobbe index 250 reference condition mand ethane number of lng from different liquefaction sites. In europe a gas interchangeability index the wobbe index is also specified.
Methods of adjusting the wobbe index of a fuel and. If two fuels have identical wobbe indices then for given. General information wobbe index and calorimeters hobre. No euharmonised criteria for safety, maintenance and emissions at inuse level. Wim wobbe index meter installation, operation and maintenance manual hobre instuments b. In comparison to a calibration gas the wobbe index for a gas can be determed. A few examples the wobbe index of a gas with a specific gravity is 0. Nl9300984a device for determining the wobbe index of a. The wobbe index wi expresses the heating value known as calorific value of gases used as fuels, taking into account the proportionality of calorific value to the specific gravity, or the density ratio between the given fuel gas and air.
Wobbe index is a measure of the amount of energy delivered to a burner via an injector orifice. So, the gas company needs to make sure the btu per cubic foot is correct, right. Given constant pressure and orifice size, the heat output of a burner is proportional to the flow volume per time the flow velocity through a given orifice size at constant pressure is proportional to the specific gravity of the gas. The wobbe index is defined as hhv vgas specific gravity relative to air and is often more stringent than the heating value specification.
Large industrial users modern industrial boilers and other large gasfired heating. The wobbe index wi is the main indicator of the interchangeability of fuel gases and is frequently defined in the specifications of gas supply and transport utilities. The principle of the gas measuring unit is based on the stability of the temperature of the exhaust gas in a proportional band of 5 c burning a gas by air mixing. Two gases differing in composition but having the same wobbe. Wobbe index analyzer wobbe index or btu analyzers figure 2 are widely used in refineries to measure btu and hydrogen in various processes, and to analyze quality of fuel gases. The wobbe index change of different fuel mixtures is plotted in fig. To measure the wobbe index a test gas is burned under standardized conditions. Cva100 wobbe index analyzer cva100 sample conditioner the primary purpose of the cva100 sample conditioning panel is to pyrolyze the sample i. The wobbe index wi or wobbe number is an indicator of the interchangeability of fuel gases such as natural gas, liquefied petroleum gas lpg, and town gas and is frequently defined in the specifications of gas supply and transport utilities. Note that the range 26 does not have to be the same as range 24. Its portfolio ranges from dew point measurement solutions, analytical laboratory equipment, nmr technology, wobbe.
Monitoring the wobbe index of natural gas using fiber. Wobbe index and gross calorific value in european networks. Typical lng heating values, methane number and wobbe index. Download bs en iso 69762016 natural gas calculation of calorific values, density, relative density and wobbe index from composition free in pdf format. Installation, operation and maintenance manual wim9900 series wobbe index meter revision. The standard scope of supply of each lhv wobbe index calorimetric system is typically composed by.
The wobbe index in the hgas standard and renewable gases. Issn 2192158x admissible hydrogen concentrations in natural. Wim wobbe index meter installation, operation and maintenance. Goffredo wobbe, an italian physicist, observed in 1927. Wobbe index sg cell option 50 mjnm3 span in 0 100 mjnm. Brief, plaintext description of system components and applications. Issn 2192158x admissible hydrogen concentrations in. The wobbe index is not a completely accurate way to.
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