Fuel gas analysis with RGQ 5 and RGQ 3

A fuel gas analysis is the metrological examination of a fuel gas to determine its composition or properties relevant to combustion, energy content, and gas quality . The specific parameters measured depend on the analytical method used and the particular application.

In a fuel gas analysis , for example, the combustion value, gross calorific value, Wobbe index, density, and other combustion parameters may be required. These values describe different properties of the fuel gas. The Wobbe index , for example, is an important parameter for the interchangeability of fuel gases in a given burner configuration. The combustion value and calorific value , on the other hand, describe the energy content under defined conditions.

RMG uses different technical approaches for this purpose. Our Gas Quality calorimeter RGQ 5 / RGQ 3 determines gas quality parameters based on measured physical properties and a correlation model. Chromatographic fuel gas analysis with the RGC 7 takes a different approach. In this method, individual gas components are separated and quantitatively determined. The appropriate method therefore depends on whether combustion parameters or detailed information about the composition of the fuel gas is primarily required.

Depending on the measurement task, precise fuel gas analysis can be performed using various measurement methods. Our RGQ 5 and RGQ 3 gas quality analyzers operate without combusting the sample gas. They measure several physical properties of the gas and use a mathematical correlation model to determine relevant gas quality parameters.

Depending on the instrument model, the parameters that can be determined include, among others , the gross calorific value, net calorific value, Wobbe index, density, and other combustion parameters. The RGQ 5 combines various sensor-based measurement principles for this purpose. These include the measurement of dynamic viscosity, thermal conductivity, and—depending on the model—additional sensor technology. This allows for continuous fuel gas analysis without the need to burn the fuel gas for measurement.

If, on the other hand, the concentrations of individual gas components are required, a process gas chromatograph such as our RGC 7 is used . It separates the gas components chromatographically and determines their proportions. Additional gas property values can then be calculated from this analytical data. This allows the measurement technology to be specifically tailored to the respective analytical task.

Fuel gas analysis can be used for various fuel gases and gas mixtures . Depending on the instrument model and specified measurement range, our measurement systems cover various compositions. These include, in particular, natural gas grades such as H gas and L gas, as well as biogas and suitable gas mixtures. Applications containing hydrogen can also be measured using instrument variants designed for this purpose.

Which gases can actually be measured depends on the measurement technology used and the specific instrument configuration. The RGQ 5 is available in different versions for various gas compositions. Certain variants, for example, take carbon dioxide or hydrogen into account when determining gas quality. Fuel gas analysis provides gas quality parameters such as calorific value, heating value, Wobbe index, or density.

For component-specific analysis, RMG offers process gas chromatographs . Depending on its version, the RGC 7 can determine individual components of natural gas, biogas, and mixed gases. Therefore, before selecting an analysis system, it is important to clarify the gas composition, the required measurement parameters, and the concentration ranges that may occur during operation.

Fuel gas analysis is used industrially wherever the changing properties of a fuel gas must be monitored or taken into account for downstream processes. Typical applications include gas supply, industrial combustion processes, power plants, and the use and processing of various fuel gases.

In gas networks , fuel gas analysis can provide relevant gas quality parameters for monitoring injection, transportation, and utilization. For natural gas, biogas, biomethane, or suitable gas mixtures, changes in energy content and other combustion properties can be detected. In industrial combustion systems, these measured values can be transmitted to higher-level control systems and taken into account when regulating the combustion process.

For continuous stationary measurements, RMG offers the RGQ 5, among other options. The portable RGQ 3 is suitable for measurements at varying locations or for temporary investigations. If detailed information about individual gas components is required, a process gas chromatograph can be used . Thus, the specific fuel gas analysis depends on the process, gas type, measurement point, and the required measurement parameters.

The equipment required for fuel gas analysis depends on whether gas quality parameters or the concentrations of individual gas components are to be determined. For the continuous determination of key combustion parameters, RMG offers the RGQ 5 and RGQ 3 gas quality analyzers. Both systems use a non-combustion measurement method.

Our RGQ 5 is designed for stationary measurement tasks. The RGQ 3 enables comparable measurement tasks in mobile applications. Depending on the specific instrument model, fuel gas analysis can provide parameters such as combustion value, heating value, Wobbe index, and density. This makes our gas quality analyzers particularly suitable for applications where changes in gas quality need to be monitored continuously or at different measurement points.

If, on the other hand, a detailed determination of individual components of the fuel gas is required , a process gas chromatograph is the appropriate measurement technology. Our RGC 7 analyzes the gas components chromatographically and uses this data to calculate additional gas property values. The choice of instrument should therefore be based on the required measurement parameters, the gas composition, the required accuracy, and the specific operational requirements.

The standards to be applied for fuel gas analysis depend on the measurement method, the required gas quality parameters, and the specific application. Therefore, there is no single standard that fully covers all aspects of fuel gas analysis. Among others, standards for calculating thermophysical properties and for specified reference conditions are relevant.

Our RGQ 5 calculates gas combustion properties based on established industry standards. These include, among others, ISO 6976:2016 as well as calculation methods according to AGA 8 and GPA 2172:2009. ISO 6976 describes the calculation of key properties of natural gas and comparable gases. When evaluating measured values, the respective reference conditions for temperature and pressure must also be taken into account.

The additional technical or regulatory requirements that apply to fuel gas analysis depend on the application. For applications in commercial or regulatory metrology, additional national and European standards as well as certification requirements may be relevant. Therefore, the measuring instrument, calculation methods, reference conditions, and required certification must always be tailored to the specific measurement task.

Continuous fuel gas analysis supports process reliability by enabling the early detection of changes in relevant gas quality parameters. If the combustion value, heating value, Wobbe index, or density fluctuate, the conditions for combustion and process control may also change. Measurement data therefore provides a reliable basis for monitoring gas-fired systems.

In combustion processes , for example, fuel gas analysis can provide information for adjusting the combustion control system. Changes in gas quality can thus be taken into account in process control. This requires that the measured values be transmitted via suitable interfaces to the higher-level controller or control system and processed correctly there.

Our RGQ 5 and RGQ 3 gas quality analyzers enable continuous or mobile measurement of relevant gas parameters. In a stationary fuel gas analysis setup, the RGQ 5 can continuously provide measurement data and make changes visible in real time. This analysis does not replace a plant’s safety systems; rather, it supplements them with up-to-date information on gas quality, thereby supporting controlled and reproducible process operation.

A fuel gas analysis requires Gas chromatographs, especially when individual components of a gas mixture must be quantitatively determined. This applies to applications in which gas quality parameters are not the sole requirement, but rather the actual composition of the fuel gas is part of the measurement task.

In gas chromatography, the gas sample is separated into its relevant components. Depending on the model, our RGC 7 process gas chromatograph determines the concentrations of specific components in natural gas, biogas, and corresponding gas mixtures. Based on this composition, other parameters such as combustion value, calorific value, standard density, and Wobbe index can then be calculated. Such fuel gas analysis is therefore suitable for applications with high requirements for component-specific gas property measurement.

If, on the other hand, combustion parameters are primarily needed for rapid process monitoring, a gas quality analyzer such as our RGQ 5 or RGQ 3 may be the more suitable solution. These instruments do not require chromatographic separation of the individual gas components for their correlation measurement. The choice therefore depends on the measurement task, gas composition, required output variables, and the applicable metrological requirements.