Abstract: An acoustic emission signal collector for monitoring leaks in furnace wall tubes employs a plurality of waveguides attached to the tubes and connected to a cross member. An acoustic emission sensor positioned on the cross member detects leaks which are propagated from the furnace wall tube to the cross member. An alternate embodiment includes tines or waveguides bent at an angle and attached to the furnace wall tubes.

Abstract: An apparatus and method for measuring high temperatures in a boiler transmits pulses of acoustic waves, from one side wall of the boiler to an opposite side wall thereof. Acoustic noise within the boiler, as well as the transmitted pulses of acoustic waves are received at the opposite side of the boiler. The received signal is digitized and compared to a digitized sample of the pulses during a time period which is more than the maximum transit time for the pulses between the side walls. A point of maximum correlation between the sample and the signal is taken as the arrival time for the pulse and is used to calculate the transit time of the pulse across the boiler. This transit time is used in turn to calculate the velocity of the pulses. The temperature can then be calculated as a function of the velocity, the molecular weight of the medium and the specific heat ratio of the medium. Each pulse has a modulated frequency between 500 and 3,000 Hz.

Abstract: A device which can determine either the velocity pressure or the velocity of a flowing gas or air stream and averages same over a predetermined period of time is disclosed. The device utilizes a three-hole yaw probe or similar sensing means which is immersed in the stream to provide measurements of both static pressure differential and velocity pressure. The device includes a null threshold detector (14) which permits the processing of velocity pressure measurements only when the static pressure differential is within a pre-set range thus insuring the proper alignment of the probe or other sensing means in the stream. A square root extractor (20) and switching means (22) are also provided permitting the measurement and averaging of the square root of the velocity pressure measurement, i.e., velocity of the stream, by the device. The velocity pressure measurements or the square root thereof are exhibited on a first digital display (28) permitting the operator to monitor the measurements as they are taken.