Selection Guidelines for Gas Separation

The choice of the technology suitable for the specific separation is related to different parameters like economics, stream conditions, product target and, also, to design considerations such as those reported below. These design parameters were introduced by Miller and Stocker for H2 separation technologies however, they ean be considered valid, in general, for gas separation. 

Reliability takes into account the on-stream factors which can cause unscheduled shut-downs. Membrane systems are extremely reliable with respect to the on-stream factor. The membrane separation process is continuous and few control components can cause a shut-down. Typically, the response to unscheduled shut-downs is rapid for GS whereas PSA systems are moderately reliable owing to the numerous valves associated with the process which can cause unexpected shut-downs. The new PSA are designed with alternative modes of operation, in which 100% of design capacity can be achieved while by-passing any failed valve or instrument, with only a slight recovery loss. Failures are automatically detected and by-passed by the microprocessor-based control system. Flowever, stronger and periodic control cycles are required. The cryogenic process is considered by refiners to be less reliable than PSA or membrane 

Absorption systems are moderately reliable. The large equipment associated with the process for avoiding the formation of degradation products and corrosion products and the presence of particles can cause unexpected shut-downs. 

Ease of expansion Very high (modularity) Moderate Very low Moderate 

By-product value Moderate Moderate High Moderate 

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