Ultrasonic method for measuring the gas holdup of gas-liquid bubbly flow in a small-diameter pipe

• Published in: The Korean journal of chemical engineering Vol. 33; no. 4; pp. 1170 - 1180
• Main Authors: Gong, Zheng, Zhao, An, Zhai, Lu-Sheng, Ren, Ying-Yu, Jin, Ning-De
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2016; 한국화학공학회
• Subjects: Biotechnology; Catalysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Materials Science; Transport Phenomena; 화학공학; High-speed Camera; Ultrasonic Measurement Method; Gas Holdup; Sound Field Simulation; Gas-liquid Two-phase Bubbly Flow
• ISSN: 0256-1115; 1975-7220
• DOI: 10.1007/s11814-015-0244-2

Based on ultrasonic sound pressure attenuation, the ultrasonic pulse transmission method is proposed for measuring gas holdup in gas-liquid two-phase bubbly flows. Two ultrasonic transducers are positioned on opposite sides of a vertical upward pipe with an inner diameter of 20 mm. To obtain the relationship between ultrasonic attenuation and gas holdup, the mean value of the first pulse sequence of ultrasonic signals is first extracted as the measured signal. We used the quick closing valve method to obtain the gas holdup as the set value. Second, the relationship between the gas holdup and measured ultrasonic signals was established. The experiment result shows that the ultrasonic attenuation rate is significantly different at low and high gas holdups, as indicated by the bubble size images with a high-speed camera. We also investigated the ultrasonic field distribution using numerical simulation. The bubble size has an important effect on the ultrasonic attenuation coefficient, which provides a further physical explanation and reference for the experimental phenomena.