Continuous High Pressure Vapor/Liquid PFR Sampling System with On-Line HPLC

Continuous High Pressure Vapor/Liquid PFR Sampling System with On-line HPLC

Wei-Ming Sun, Martin Johnson, Edward M. Sheldon

Abstract:

An automated sampling approach utilizing on-line HPLC had been designed for continuous thermal tube and hydrogenation tube reactors.   The system is an integrated part of the automation system used to control continuous plug flow tube reactors.  A six port, two position column switching valve is used in conjunction with a fixed volume loop to introduce the sample.  There are 2 major challenges for directly connecting HPLC with continuous flow reactor.  First, the inlet flow of HPLC needs to be only liquid phase without any vapor phase so that an accurate and precise dilution can be accomplished.  Second, the control reaction back pressure is critical; therefore, the interface with the HPLC must be accomplished without reaction pressure perturbation.  This approach utilizes a system that can directly connect to wide range of pressure (0-1,000 psig) continuous flow reactor without affecting the back pressure of the reactor.  In addition, this system is able separate the liquid and vapor phases for sampling to the HPLC loop.   The small amount of product can be diluted to the desired concentration, and automatically mixed, then, the homogenous sample solution is directly transferred to the HPLC loop for injection. In summary, the system can automatically take a 1 ml vapor/liquid sample from a continuous reactor outlet stream at pressures up to 1000 psig, separate the liquid from the vapor, precisely and accurately dilute the liquid phase, mix the diluted sample, and inject into and HPLC that can be located up to 25 meters from the continuous reactor.