An industrial-prototype acoustic array for real-time emulsion layer detection in oil storage tanks

In this paper, a low-cost and nonradioactive industrial field prototype device that provides continuous and real-time information of the vertical distribution of the oil, water, and emulsion (oil-water mixture) in the oil tank separator is presented. The device which is capable of detecting the emulsion layer with 15 cm resolution is installed into the vessel through an 8" (i.e., 20.3 cm) flange. It consists of a one dimensional array of 28 ultrasonic transducers which are activated in a time multiplexed manner by a separate transmitter located at the top of the tank. The transmitter explores the collected data, using a dedicated pattern recognition algorithm, to provide the position of the emulsion layer which is then transferred to the control room using industrial standard protocols (i.e., RS-485 and 4-20 mA output). The whole system is intrinsically safe and uses one single power source (12 VDC).