(82f) C4 Extractive Distillation Using Chuangju’s PFSTTM Vertical Sieve Spray Tray

With the rapid expansion of the ethylene industry in China, the C4 hydrocarbons production as a by-product exceeds 6 million tonnes per annum. The extractive distillation columns used to separate C4 presently have issues of high pressure drop, lower than design throughput, poor separation and high steam consumption due to its high foaming tendency of the solvent and a high liquid load.

This paper will present two industrial case studies using ChuangJu’s proprietary PFST^TM spray tray design to solve the above mentioned problems. The PFST^TM tray is designed with a sandwich plate to catch the liquid that has been sprayed out of the vertical sieve caps after mixing with the vapor. The liquid is then channeled down to the next tray by a multiple down comer design to handle high liquid load, thus eliminates the problem of liquid back mixing. With this design, the vapor and liquid phases come to contact counter-currently with the maximum concentration driving force, everywhere on the tray without any liquid flow and concentration gradients. The spray action of the vertical sieve cap reduces the foaming tendency.

In the first case study, PFST^TM trays were used to revamp two C4 extractive distillation columns and one de-gasing column for the Ningbo Haode Chemicals. After the revamp, the throughput is increased by 70%, the steam consumption reduced by 35%, the solvent loss is reduced by 165 t/a.