Coal-derived syngas purification and hydrogen separation in a supersonic swirl tube

Coal gasification is a means to produce synthesis gas (or syngas) which may then be processed further to produce hydrogen of desired purity. Ultimately separation of the H-2 and CO2 from the process stream is required. Membrane technologies are currently applied to such separation processes. Here a theoretical approach derived from aerospace technologies is shown to have promise as a robust method for extracting H-2 from syngas. It is based on a swirling expansion process in a specially designed supersonic flow nozzle which combines both condensation and segregation of the unwanted species. The quasi-one-dimensional equations for swirling compressible flow with rate controlled condensation are derived, the dynamics of the separation of condensed species is described, and preliminary solutions for cases of practical interest are presented. This theoretical foundation is shown to support the feasibility of an industrial-scale device incorporating this effect and lays the groundwork for future experimental investigations. (C) 2011 Elsevier Ltd. All rights reserved.