The failures of abrasion-resistant refractory linings have been well-documented in the petrochemical industry for the last 20 years, and have been at the centre of emergency shutdowns and critical paths during planned turnarounds, leading to millions of lost profit opportunities and early replacement of critical processing equipment – especially in FCC vessels.
What has been notable, is that the discussion related to these failures has typically revolved around the secondary symptoms of the failures, rather than its root cause.
These failures directly threaten process performance and safety, equipment longevity, and operating costs and profits. However, there are proactive strategies to defend against these failures. An engineering and design approach that allows mitigation and control over the key failure mechanisms can prevent millions of wasted expenses and countless unsafe manhours spent in repairing these failures.
Refractory lining bypass is a costly problem that affects the processing efficiency of FCCs.
The observed primary cause of the bypass phenomenon lies in the numerous pathways and gaps created in conventional closed-cell systems. This allows gases and liquids to travel behind the lining due to a differential pressure created that disrupts the natural and intended flow of equipment.
There are only two defined types of systems, closed-cell systems (i.e. hex metal), and open/non-cell systems (i.e. s-bars, k-bars, half-hex cells).
Semi-closed systems that disrupt the perpendicular bypass flow path can prevent bypass and its consequential failure mechanisms such as weld corrosion, carburization, and structural degradation.
Specifying semi-closed systems can provide long-term equipment performance and bypass mitigation, helping vessels such as cyclones, risers and other critical internal equipment reduce maintenance requirements and increase their longevity.
