Hydrogen Separation Systems

These results are not unlike those reported by others, for separation of gases with molecular sieves. For example, when HgS is stripped from natural gas with a Davison 5A molecular sieve, the reaction front is typically 1 to 5 feet at superficial gas velocities of 15 to 30 feet per minute (lO). From this perspective, the operation of a hydride-hydrogen separation system is similar to conventional units. 

The first company to produce a successful membrane-based gas-separation process was Permea, now a division of Air Products, which introduced hollow-fme-fiber polysulfone membranes for the separation of hydrogen from ammonia reactor purge gas in 1980. This application was an immediate success the feed gas was clean and free of condensable components that might damage the membranes, and the value of the recovered hydrogen provided short payback times. Within a few years, many ammonia plants worldwide had installed these units. Several hundred hydrogen-separating systems have now been installed by Permea and its competitors. 

Assume initially that a phase split can separate the reactor effluent into a vapor stream containing only hydrogen and methane and a liquid stream containing only benzene, toluene, and diphenyl and that the liquid separation system can produce essentially pure products. 

Often repair of the found defects is extremely undesirable. Therefore, for discontinuities which are potentially hazardous, it is very important to have a onfirmation of their stability. In this case monitoring of potentially hazardous discontinuities is well supported by automated UT systems and based on the comparative analysis results, the actual data from examination of a section of the welded joint of a (hydrogen) separator are given in Figures 5,6. 

Pressure swing adsorption cycle sequence for a four-bed system. (Adapted from Miller, G.Q. and Stocker,., Selection of a Hydrogen Separation Process, UOP Report, January 1999, available at http //www.uop.com/ objects/SelOfHydroSepProc.pdf Cassidy, R.T., Adsorption and ion exchange with synthetic zeolites, in ACS Symposium Series, ed. W.H. Flank, American Chemical Society, Washington, Vol. 135, p. 275,1980.)... 

Balachandran, U., T.H. Lee, S. Wang, G. Zhang, and S.E. Dorris, Current Status of Dense Ceramic Membranes for hydrogen Separation, 27th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL, March 2002. 

Roark, S.E., Mackay, R., and Sammells, A.F., Hydrogen Separation Membranes for Vision 21 Energy Plants, Proceedings of the International Technical Conference on Coal Utilization Fuel Systems, 27(1), 101, 2002. 

A method to reduce degradation/deactivation of a phosphite modified rhodium hydroformylation catalyst in the separation system involves feeding a diene such as butadiene to the vaporizer to convert the phosphite-modified rhodium catalyst to a more stable form. [34] In the reactor, the diene is hydrogenated and catalyst activity is restored. 

---