APPARATUS FOR MEASURING A GAS VALUE

摘要

An energy meter (2) comprises a combustible fuel gas inlet (48) and a fuel g as outlet (50) and a central tube (12) along which the gas flows in travelling from inlet to outlet. Ultra-sound transducers (52 and 54) and a control (56) comprising computer means form a system whereby the speed of ultra-sound signals travelling through the gas between the transducers can be measured a nd utilised in the control to calculate the volumetric amount of gas which has passed through the meter. The ultra-sound signals pass through apertures (33 and 38) in the walls (24, 26) of chambers (32, 34) containing the transducer s. Another ultra-sound transducer (66) in the chamber (32) and connected to the control (56) acts as an emitter and receiver of ultra-sound signals reflecte d by reflectors (68 and 70). These signals travel through the fuel gas in chamber (32) and their attenuation is observed and measured by the control when they are received by transducer (66). The measured attenuation is used by control (56) to derive the calorific value and/or Wobbe index of the gas, an d the control uses the volumetric amount of gas and the calorific value and/or Wobbe index to derive the amount of energy provided by the supply of the gas .