(119d) Evaluation and Testing of a Two Phase Feed Distributor

Feed locations in a distillation tower represent transition points where liquid and vapor  volumetric rate change significantly on each side of the distributor. Poor distribution may cause pre-mature flooding of the trays directly above and/ or below the distributor, which can result in capacity shortfall. Flashing feeds add to the complexity of the design and have been known to significantly impact the ability of distributors to achieve the expected capacity. This paper discusses the evaluation, testing and re-design of feed distributors intended for the re-tray of a Depropanizer in an olefins facility. Physical space constraint and a significant vapor fraction in the feed streams were challenges imposed on the design.

A full scale test of the originally proposed distributor, tested at the volume fraction expected for the design fluids, proved unsuccessful.  Using flow regime mapping techniques and momentum equations for stratified flow, the system was scaled down to lab scale with air-water test fluids.  Testing of various distributor designs at lab scale with air-water was completed and the performance of the successful design was simulated with CFD at lab scale with air-water, for validation, and at full scale with the process fluids.