Designing And Failure Of Monolithic Refractory Structures – Part 1
The design of industrial refractory structures has traditionally been based on empirical or trial and error methods evolved over many years. Until recently, design methodology has been based on heat transfer analysis for materials selection and a 1D heat transfer analysis to determine the interface and shell temperature under perfect conditions.
Previous research has shown that failure of refractory linings is primarily due to creep rupture of the steel anchor at or near the interface zone. This is due to the stress induced by the thermal load, which is generally a low stress (<10MPa) at high temperatures. Given a high enough stress, the anchor material will fail in a short duration (e.g. minutes) but at relatively lower stress levels, the anchor will deform and fracture due to creep mechanisms over time (e.g. hundreds or thousands of hours).
The current approach to anchor design and spacing which has been developed from experience and applied “rule of thumb” is considered inadequate and fundamentally incorrect. We have set out the engineering principles needed to when determining anchor spacing and selecting anchor material. Our research has shown that anchor design needs to consider maximum process temperature, corrosion of steel, lining weight, anchor placement, creep rupture stress at the maximum temperature and thermal strain.
The reliability of refractory anchors in refractory lined process vessels is the key to refractory efficiency and safety.