Comparing the results of acousto ultrasonic-echo (AU-E) with physical measurements for several blast furnace hearth refractory linings
The parameter that has the largest impact on the campaign life of a blast furnace is the health of the hearth refractory lining. When this lining is severely deteriorated, the furnace must be shut down for either a repair or a reline. This means that it is crucial to continuously monitor the health of the hearth refractory lining. However, this has proven to be difficult in the past due to the obscurity and inaccessibility of a blast furnace hearth. To date, the most common method of monitoring the hearth lining has been to measure the temperature of the hearth the and corresponding heat fluxes. While this information is useful, it can often be inaccurate and inconclusive when calculating the thickness of the hearth refractory lining. To accurately measure refractory lining thickness, Acousto Ultrasonic-Echo (AU-E), a technology based on the stress wave propagation principals, was developed in late 1990s. AU-E can accurately detect refractory and skull thicknesses, as well as the position of cracks, joints and gaps within the refractory. As advances in technology bring blast furnaces into the modern era of data collection, interpretation and analysis, AU-E will play an important role in making informed decisions, increasing efficiency, and extending campaign life.
In this paper, we present a brief scientific background on the AU-E technique and describe its application for monitoring the hearth refractory lining in blast furnaces. Case studies which have provided lessons learned are also presented to demonstrate comparisons between AU-E and temperature measurements with drilling and physical verifications.