Mass-transfer columns are one of the largest components of process plant investment and operating costs. Every year, numerous publications cover various troubleshooting and problem solving techniques for poorly operating columns. The issue addressed in these is how to fix a problem after it occurs. The authors propose to approach this from a different angle, how to avoid problems in the first place.
The initial step in this procedure is to identify the root causes of why towers fail to perform. Literature sources of information on tower failures tend to be biased towards situations where the fewest embarrassing details are present in the history of the failure. To avoid this bias, a listing of key details of cases stripped of references to particular units is presented. Each failure is categorized by the combination of root causes that lead to it. From this analysis, conclusions are shown identifying areas of improvement for industrial mass-transfer design practice.
A frequency breakdown or reasons towers do not work is presented.
Tower failure reasons are broken down into avoidable and non-avoidable
problems. The majority of tower difficulties arise from avoidable
problems. Categorization of avoidable failure events places errors
Avoidable error classes include:
Unavoidable error classes include:
For each type of problem, the results are characterized as a slight, moderate or severe situations. Recommendations founded upon the experience base presented are made for guidance of engineers for review of designs and equipment.
The main conclusion is that the major source of tower failures lies in management systems, decisions, and resource allocation. Secondary technical issues account for a much smaller proportion of failures. While failures may occur in any size tower or service, technical issues are especially important in large diameter, extreme loading (very high and very low loadings), stringent product specification services and at-the-edge designs.
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