Blast Furnace Hearth Thermal Assessment and Identification of Wear Zones

Abstract

Blast furnace hearth refractory is exposed to harsh conditions during operations due to chemical and physical degradation. The blast furnace hearth experiences high temperatures, thermal stress, chemical attack, erosion due to fluid flow and steam oxidation. This makes the hearth performance critical to the overall blast furnace campaign life.¹ Understanding the extent of refractory loss and the nature of the protective skull is important to avoid expensive repairs and to optimize production while extending campaign life. Combining two non-destructive techniques—stress wave analysis (Hatch Acousto Ultrasonic-Echo technology, AU-E)² and heat transfer analysis using refractory thermocouple and cooling system measurements—the conditions of the hearth refractory and protective skull can be assessed.

This paper describes a combined thermal assessment using AU-E measurements and thermal data to more accurately predict the wear profile of the hearth while in operation. This method was also used for identification and confirmation of regions experiencing further wear over time. Transient heat transfer analysis was completed to determine the thermocouple response time to operational changes or events in the furnace. To gather a better understanding of the problematic areas in the furnace, such as high temperature regions and tapholes, 3D analysis was used.