| 摘要 |
PURPOSE:To measure a Wobbe index on-line with high resolving power, by applying opera tional processing to the signal from a light interference measuring apparatus on the basis of knowledge such that natural or petroleum type fuel gas is proportional to a refractive index not only in its heat generating quantity but also in its specific gravity. CONSTITUTION:The light incident from a light source 10 is incident on the first and second cells 2, 3 and interference is generated on the basis of the difference between the refractive indice of the fuel gas and standard gas 8 received in the cells 2, 3 to be converted to an electric signal by a photoelectric detector 12. In urban gas prepared by carbretting natural gas with petroleum gas, a refractive index N=(n-1)X10<6>, heat generating quantity Q and specific gravity (d) are correlated in linear function with extremely high accuracy regardless of the component thereof. Therefore, the data outputted from a specific gravity operation circuit 14 is extracted by an extraction of square root operation circuit 15 to operate d<1/2> and the ratio of d<1/2> and the heat generating quantity Q is operated by a ratio operation circuit 16 to be converted to a Wobbe index. Since the detection time of the refractive index N and the predetermined operation time from the refractive index are extremely short, the Wobbe index outputted from the circuit 16 shows the property or burning characteristic of the fuel gas presently flowing through a gas supply line L.
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