The Potential of Energy Savings in Oxygen Production by Pressure Swing Adsorption

Abstract

The pressure swing adsorption (PSA) units are widely used as an oxygen source. The second PSA unit outgoing stream contains a dry mixture of O2 in N2 that is mostly exhausted into the atmosphere. Utilization of this stream's potential and waste compression heat leads to an increase in the unit's overall energetic capacity and the ecologically more friendly processing. This paper aims to demonstrate the above-described possibilities in the case of the oxy-fuel combustion unit. The following four options for integrating PSA technology were analyzed: i) single or dual compression, ii) utilization of waste compression heat for coal or biomass dewatering, iii) utilization of dry waste gas from the PSA unit for coal or biomass dewatering, and iv) energy recovery by an expansion of pressurized oxygen before combustion. The greatest potential for practical application was found for the usage of dual compression (saving of 10 % of electricity) and utilization of waste compression heat for coal or biomass dewatering. In this case, the saving of 5.3 % and 10.4 % of lignite and wood respectively can be reached depending on fuel moisture for reference fuel conditions.