Ultrasound Measurements of Temperature Profile Across Gasifier Refractories: Method and Initial Validation

Abstract

A gasifier’s performance and the longevity of its refractory are directly affected by the temperature of its reaction zone. One of the key technological challenges impacting the reliability and economics of coal and biomass gasification is the lack of temperature sensors capable of reliably performing in a harsh gasification environment over extended periods of operation. In this paper, we describe and experimentally validate a novel approach that uses noninvasive ultrasound to measure the temperature distribution across the refractory or other containments, including the temperature of the hot side of the refractory. This method uses an ultrasound propagation path across a refractory that has been engineered to contain multiple internal partial reflectors. Beginning with an ultrasound excitation pulse introduced on the cold side of the refectory, a train of echoes created by partial reflectors is acquired and used to determine the speed of sound in the corresponding segments of the refractory. By using an experimentally established relationship between the speed of sound in the refractory material and the temperature, the temperature distribution across the refectory is obtained. The initial validation of the proposed approach is reported for a model cementitious refractory heated up to 100 °C. The options for incorporating partial ultrasound refractors into the refractory, the achievable accuracy, and the spatial resolution of the measured temperature profile are discussed.