Measuring Natural Gas In Boiler And Furnace Applications

Optimization of a combustion process can result in significant savings in fuel costs. Proper control of the air/fuel ratio to a burner results in the highest possible efficiency – the maximum steam output (or heat generated) for the least fuel consumption. Accurate flow measurement (and the resulting improved control) of the natural gas and combustion air is critical to achieve peak efficiency. A wide variety of flow measurement technologies are used including orifice plates/DP transmitters, vortex, turbine, variable area and thermal mass flowmeters. The critical factors in selecting the best flowmeter for combustion applications are mass measurement, accuracy, repeatability, turndown, installation, safety and reliability.

Combustion is a chemical reaction; therefore, controlling the air/fuel ratio based on mass is essential. The Fox Thermal Mass Flowmeter provides a direct mass measurement in Standard Cubic Feet per Minute (SCFM) or Pounds Per Hour (lbs/hr). Alternatively, differential pressure type devices (i.e. orifice plate with differential pressure transmitter), vortex, turbine and variable area meters provide only a volumetric flow measurement. With these devices, changes in process pressure or temperature will result in significant measurement error. It is possible to obtain an inferential mass flow measurement by compensating the volumetric flow with pressure and temperature measurement in a flow computer. However, this combination of instruments is expensive to purchase, install and maintain. A direct mass measurement with a Fox Thermal Mass Flowmeter is your best solution.