Diagnosing and Resolving Process Flow Maldistribution  in a Packed Column

Diagnosing and Resolving Process Flow Maldistribution

 in a Packed Column

 

Lowell Pless¹, Nicholas Graham², Mason Bieker²Â and Rodney Thompson¹, (1) Tracerco, Pasadena, TX, (2) ChevronPhillips Chemical Co, Baytown, TX

An olefins column was having separation problems. A project team was assembled to first diagnose the source of the problem and then to recommend and implement a solution. First step taken by the project team was to use gamma scans to study the hydraulic performance of the column.

The column was configured with a top section of structured packing and a bottom section of one-pass trays. Initially it was not known what or where the potential problem was so both sections of the column were scanned at â??normalâ? process conditions.

The gamma scan results, including tomography scans, indicated that the packed section was operating with some degree of process flow maldistribution while the trays appeared to be operating satisfactorily. Now the debate moved to whether the flow maldistribution through the packed bed was liquid (liquid distributor) related or vapor related.

The project team devised a novel approach to plant test whether the packing maldistribution was liquid related or vapor related. Gamma scans were used to ascertain the effects on the maldistribution from the plant test. The gamma scan results confirmed to the project team what then needed to be revamped in order to mitigate the columnâ??s separation problem. Some internal hardware was re-designed and later installed after which the column began to perform its intended separation.

This presentation will describe the plant test procedure and the thought processes based on the scan results, other process data and hardware design criteria. The process improvement plan that was designed and implemented will be discussed.