James Critser Davis

Facilitated transport membrane hybrid systems for olefin purification

Abstract A new membrane system has been developed by BP for refinery and chemical plant olefin purification and recovery. This facilitated transport system, coupled with distillation, offers lower capital and operating costs than conventional distillation alone. Initial results on lab scale hollow fiber devices indicate membrane flux ranging from 8.75×10−6 to 8×10−5 m3/m2/sec (2.5 to 23 scfd/ft2) and selectivities from 150 to 300. Pilot plant experiments on propylene/propane and ethylene purge gas recovery over three to six months duration show membrane stability and product purity of 98.5% or greater using refinery grade propylene feed. Hybrid system optimization data for membranes and distillation indicate that using a side draw from the distillation tower provides advantages in terms of membrane area, purity of feed to the membrane, and low per-pass recovery coupled with high overall propylene recovery. Membrane performance data under various conditions will also be presented. In addition to performanc...

Affinity Dialysis–A Method of Continuous, Rapid Metal Ion Separation Using Dialysis Membranes and Selective, Water-Soluble Polymers as Extractants

Abstract A membrane process utilizing dialysis and selective complexation by water-soluble polymers has been developed. This process, termed affinity dialysis, has been shown to selectively extract and concentrate both cations and anions in a manner similar to ion exchange or solvent extraction. The selective removal of calcium from sodium with selectivity of about 30, removal of chromate ion from dilute streams, and separation of transition metal ions such as Cu/Fe and Cu/Zn have all been successfully demonstrated. Effects of different polymers, polymer concentration, temperature, and flow rates have been studied. The effect of increased polymer concentration is to increase product concentration if appropriate changes in feed, polymer solution, and strip flow rates are made. A continuous polymer solution recycle and regeneration system has been constructed and operated with Cu/Zn and chromate/chloride feed streams. Removal of over 95% of the desired ion in one pass and concentration factors of product ov...