Selection Separation Method for Hydrogen and Light Hydrocarbons Gases from Waste-Gas Streams of a Petroleum Refinery

The four main processes for hydrogen upgrading in refineries include pressure swing adsorption, selective permeation using polymer membranes, cryogenic separation, and dephlegmation. Each of these processes is based on a different separation principle and, consequently, the process characteristics differ significantly. Selection of an appropriate hydrogen and light gas separation process depends not only on economics but on other project considerations such as process flexibility, reliability, and ease of future expansion. A review of the separation process characteristics and equipment is provided in this article, followed by discussions of other project considerations. General and application-specific selection guidelines are then presented, along with process integrations that take advantage of the complementary characteristics of the four processes. Due to the worldwide depletion of petroleum reservoirs and the growing use of hydrotreating in petroleum refineries, much attention has been given to light hydrocarbons and hydrogen recovery from refinery waste streams.