Performance Comparison of Different Blast Furnace Hearth Designs using a Novel Structural Refractory Assessment Methodology

Abstract

The blast furnace hearth refractory system is exposed to complex chemical attack, erosion and thermal and mechanical loads.This includes thermally-induced stresses, internal pressure, hydrostatic gravity loading from the hot metal, and surcharge loads due to coke and other burden above the hearth. The hearth is a region of primary concern since excessive refractory failure and degradation limits the furnace campaign life and leads to premature and costly repairs. A robust hearth refractory lining design is needed to avoid or minimize furnace downtime and maximize the campaign life.

Several competing design philosophies have emerged for the hearth bottom and side wall design such as big beam blocks, small block, ceramic pads, ceramic cups, various bricking patterns and orientations, various brick materials, etc. Comparing different hearth design options is a challenging task, especially when the thermal performance and susceptibility to wear in the refractory are not comparable. In this case, design options can be more effectively compared if the structural performance can be quantified, e.g., extent of gap formations and crushing / cracking of bricks in the refractory system.

Structural modeling of hearth systems is a valuable tool in characterizing structural performance, and can provide a more reliable way of assessing the hearth performance and identifying potential design flaws that could limit the furnace campaign life.