Hydrogen recovery and purification from refinery, petrochemical and ammonia plant gas streams.
Feed: Refinery streams include hydroprocessing unit purge streams, catalytic reformer offgas, fuel gas streams and steam reformer (feed preparation/product purification). Petrochemical streams include: olefin plant process and recycle streams, polypropylene recycle streams, methanol plant purge, syngas streams from steam reforming and gasification processes for hydrogen (H2)/carbon monoxide (CO) ratio adjustment and/or process efficiency improvement.
Product: Hydrogen purity of 90–99% is typical of most applications. Hydrogen recovery range is from 80% to 95+% depending on operating conditions and customer requirements. In refining applications, the hydrocarbon by-product, non-permeate stream leaves the unit at feed pressure with up to 99% recovery.
Purification is based on polyaramide or polyimide hollow-fiber membrane modules with high resistance to typical hydrocarbon stream contaminants. The hollow fibers are assembled in a patented radial cross flow permeator module. Modules are combined in pressure vessels to provide maximum system performance and to minimize space requirements. Hydrogen membrane systems typically include a coalescing filter (1), a preheat exchanger (2) and membrane separators (3). The membrane system’s modular nature allows for maximum flexibility in system capacity and permits future expansion.
Consistent H2 recovery and product purity can be maintained through wide fluctuations in feed composition, operating pressures and feed flow rates. The systems are skid-mounted for compactness, minimal installation costs and are designed for unattended outdoor operation. A small amount of low-pressure steam, instrument air and power for instrumentation are the only utilities required.
Economics: MEDAL hydrogen membrane systems are characterized by low capital and operating costs, and a high return on capital.