Laser ultrasonic furnace tube coke monitor. Quarterly technical progress report No. 2 for reporting period August 1, 1998--November 1, 1998

摘要

This report summarizes the technical progress achieved during the first quarter of the ERIP project entitled, ''Laser Ultrasonic Furnace Tube Coke Monitor.'' The focus of work during this reporting period was the testing of a novel device for introducing a broad bandwidth ultrasonic pulse at the surface of a simulated furnace tube. The device employs a sacrificial stand-off composed of a fusible alloy that conforms to hot furnace tube surface upon contact. Conventional high-temperature couplants have a maximum operating temperature of about 550(degrees)C, which limits their use for contact against ethylene cracker furnace tube surfaces that typically operate at about 1000(degrees)C. In the absence of a couplant, insufficient ultrasonic energy can be transmitted from the transducer to the tube surface. By using a fusible alloy, the device efficiently couples the transducer to the hot furnace tube surface, even for rough and convex tube surfaces operating at temperatures of 1800(degrees)F and above. Initial tests confirmed the ability to resolve pulse echoes in a simulated furnace tube using a 5 MHz piezoelectric transducer with a fusible stand-off.