The decision to replace catalyst in a fixed bed reactor is a balance of costs and benefits. Replacement timing may be affected by synergies with other scheduled maintenance. Product inventories may need to build prior to replacement, in order to cover sales if production is halted.
This article will focus on the economic evaluation of catalyst replacement, and give you some tools to make replacement decisions and optimize the replacement cycle time. Typically, plant projects are evaluated over a fixed period of time, and prioritized based on a cash flow metric such as net present value (NPV) or after-tax rate of return (ATROR). In the case of catalyst replacement, the issue is not so much “if” as “when”, so the options involve different time periods for evaluation. This discussion applies to both catalyst replacement and catalyst regeneration, each with their own costs and benefits.