Hydrogen upgrading

This source of hydrogen is being effectively utilized with the aid of the cryogenic hydrogen upgrader to recover and purify hydrogen for return to such refinery applications as residuum hydrocracking and hydrodesulfurization. 

The hydrogen upgrading in refineries is traditionally carried out by means of PSA and cryogenic separation processes. However, the application of membrane systems for this type of separation is rapidly growing toward the commercial level, owing to the advantages related to the low capital costs, low energy requirements, and modularity. 

In many refineries hydrogen upgrading processes, the impurities to be rejected include hydrocarbons that have value significantly above fuel value. This is particularly true for olefin-containing streams. The relative amounts of high-value hydrocarbons and the incremental cost of further separation determine whether by-product recovery is an important parameter to be considered. 

Oelert, H. H. Integrated Two-Stage Noncatalytic Hydrogenative Upgrading of Petroleum Residue (1) Reactions and Product Distribution Erdol, Erdgas, Kohle 103 (1987) p. 437-440. 

Distillation and related vapor-liquid processes are by far the most widely used molecular separation processes in the petroleum, natural gas, petrochemical, and chemical industries, as mentioned earlier. It is highly unlikely that adsorption will ever rival distillation in frequency of use, but adsorption will continue to m e inroads into its domain. Adsorption s serious competition for the separations for which it is now used would seem to come chiefly from membrane-based processes, and especially fixed-membrane processes. For example, Monsanto s Prism hollow-fiber-based process has been commercialized in a number of hydrogen-upgrading applications, and a growing number of other applications are being pursued. 

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