Design of refractory lining 

In high temperature furnaces, it is often required to design the refractory lining which is compatible with the physico-chemical-thermal requirements on one side and energy saving on the other hand. Mostly, furnaces are multi-layered lining with refractory materials of different thicknesses and thermal conductivities. Whereas the refractory lining facing the reaction chamber should meet different physical, chemical and thermal requirements, like high refractoriness, low porosity, chemically inertness etc.; refractory lining facing the metallic shell must have insulating properties preferably material of low thermal conductivity.  In the design of the multi-layered lining, the thickness of each layer is an important issue. Optimum thickness would not only save cost of the refractory but also control the weight of the vessel.

Several reactors in high temperature furnaces like matte smelters, converters, rotary kiln etc. carry out processes at high temperatures and hence are lined with the refractory materials. An optimum thickness of the lining would be desirable for minimum losses and optimal cost. In most of the reactors the walls are either rectangular or cylindrical. In the following one dimensional heat flow through flat and cylindrical walls of refractory material is considered at steady state. It is considered that the temperature gradients are across the thickness of the wall whereas the other faces are at uniform temperatures.