Chapter 11 - Furnace construction and materials

Abstract

This chapter examines the function and principal requirements of the furnace structure together with the materials available for furnace construction. Design of the furnace structure and choice of construction materials is a complex topic. In its simplest form a furnace consists of a casing with a heat source, usually a flame, to provide the process energy. The need for furnaces to accommodate a wide temperature range, from ambient to, in some cases, up to 2000°C provides a significant challenge to both design and maintenance engineers. Resolving these issues is one of the designer's principal responsibilities and requires careful consideration of all the issues, including choice of materials such as which ceramic refractories are appropriate and methods of accommodating differential expansion. Even materials with nominally similar specifications can vary in their in-service performance owing to different source of raw materials, in the case of refractories, and different heat treatment processes in the case of sophisticated high performance alloys. To achieve optimum furnace performance, and long life between repairs, it is essential to fully understand the duties required from both refractories and high temperature metals. Help in building furnace should be sought from advisory services and research associations such as CERAM Research (refractories) and the Stainless Steel Advisory Service (high temperature metals). Individual suppliers will also advise on their own materials but such advice is unlikely to be unbiased.