ABSTRACT
Refractory lining design and installation are addressed here with respect to the
thermal and mechanical behavior of the lining system. The chemical aspects of
selecting refractory materials with respect to lining design and installation are
not addressed here. Fundamentally, acid and basic processes dictate the type of
refractory material (silica/acid and magnesia/basic) to be used. The primary purposes of refractory linings are to insulate the process temperature from the sur-
rounding ambient temperature, to contain the product material, and to restrict
the support structure (typically a steel structure) temperature to reasonable tem-
peratures such that the steel maintains reasonable strength. Typically, carbon
steel begins to lose strength and stiffness (yield stress and elastic modulus,
respectively) at temperatures that exceed about 8008F (1). Based on the process temperature, the basic geometry of the refractory lining system, and the type of
support structure, the second concern is the expansion forces developed in the lin-
ing and reacted by the steel support structure. This chapter describes the classical
brick shapes, the primary classes of refractory lining geometries, the fundamental
expansion behavior of each of the refractory lining geometries, the fundamentals
of the need for lining containment, and the fundamentals in the use of expansion
allowance material in the refractory lining system. Without appropriate lining
containment, no expansion forces are developed and expansion allowance
materials are of no use. Understanding the basic expansion behavior of each of
the classical refractory linings configurations also greatly assists in knowing
where to place expansion allowance material and the amount of expansion allow-
ance material. Compressible blanket and board materials and plastics sheets are
often used as expansion allowance in refractory linings. Guidance is provided in
the amount of compressive displacement that can be anticipated in these
materials. Most refractories tend to soften, or go plastic, at elevated temperatures,
as shown in Figure 1. Figure 1 is the static compressive stress-strain data (SCSS)
for a 70% fired alumina brick. This behavior must be accounted for in the instal-
lation of expansion allowance. It should also be kept in mind that when the brick
lining is installed, special care is given to making sure that the brick mortar joints
are completely aligned. However, upon heatup of the brick, as expected, expan-
sion occurs more on the hot face than on the cold face. As a result, misalignment
occurs in the lining in the heated operating condition. The resulting compressive
bearing loads do not occur over the complete brick bearing surfaces in the heated
condition. Because of this behavior, “hinges” are developed in the lining in which
a small portion of the brick bears the compressive load. These hinges occur at
usually predicted locations based on the lining geometry. The locations of
these hinges will be discussed, which will assist in the location of expansion
allowance and also assist in zoning methods in the lining installation. That is,
more crack-resistant brick should be placed in the hinge regions where higher
operating stresses exist.
