GAS PHYSICAL PROPERTY MEASUREMENT METHOD AND DEVICE

PROBLEM TO BE SOLVED: To measure physical properties related to the combustion of a combustible gas in real time by providing a sound velocity-deriving means or the like for obtaining the sound velocity of a gas to be measured from time when ultrasonic waves are propagated in the flow of the gas to be measured. SOLUTION: A gas to be measured flows in a specific direction in a measurement part 7. An ultrasonic wave is transmitted from one of ultrasonic transmitters/receivers to the other, and the sound velocity of the gas to be measured is obtained by a sound velocity-deriving means 18. The specific gravity of the gas to be measured is obtained from the sound velocity by a specific gravity-deriving means 20b. Regarding the specific gravity, since numeric values are related to the sound velocity of gas, the values are obtained from the sound velocity of the gas, thus obtaining the specific gravity of the gas, thus measuring the specific gravity of a product gas in real time. Also, a calorific value-deriving means 20a obtains the calorific value of the gas to be measured from the sound velocity, and an Wobbe index-deriving means 20c obtains a Wobbe index from the calorific value and the specific gravity.