Modeling, validation and exergy evaluation of a thermally-integrated industrial cryogenic air separation plant in Colombia

Abstract

This work deals with the modeling, computer simulation, validation, and exergy evaluation of a ~40 ton/h industrial air separation plant located in Colombia. The model was implemented in Aspen Hysys® at the corresponding operating conditions of the facility. Initially, the reliability of the model was verified by comparison with data reported in the plant manual (EDM) from the base operating point. An additional validation was performed by comparison with historical records which involved a statistical analysis of plant metadata. The model showed good agreement with both sets of data, displaying deviations< 10%, and it was used to identify that compressors (1325 kW), multichannel heat exchanger (519 kW) and the high-pressure column (448 kW) exhibit the largest exergy destruction rates. By mean of a sensitivity analysis, main controlled variables affecting the process performance were identified. This enabled to detect the feasible operating zones, and a local minimum of exergy destruction for each variable. The overall exergy efficiency was estimated in 0.18, and the specific power consumption with respect to produced oxygen was 1.26 kWh/Nm3 O2. Results indicate that plant performance needs to be highly improved to reduce energy intensity and that the obtained model is suitable for further optimization.