Energy Improvement of Adsorptive Natural Gas Dehydration Unit by Layering the Bed

Abstract

This work investigates the energy efficiency improvements achievable by a layered adsorption bed combining 3A zeolite and silica gel for natural gas dehydration via temperature swing adsorption (TSA). Simulation results indicate that extending the silica-gel bed relative to the zeolite layer enhances working capacity and cycle time. For an industrial-scale adsorption bed (3.5 m length, 5.5 m diameter) processing natural gas at a flow rate of 23929 kmol/h with an inlet water content of 1852 ppm, the dehydration cycle time was 760 min using a single 3A zeolite bed. By adopting a layered configuration with silica-gel and 3A zeolite layers at optimized lengths (3.7 and 1.8 m, respectively), the cycle time was extended to 1530 min. This adjustment reduced the number of annual cycles from 632 to 314. It decreased the energy consumption from 19.57 MJ/kg (of water removed) in the single-layer bed to 4.51 MJ/kg in the layered configuration. Additionally, the lower regeneration temperature required for silica gel (150 °C compared to 225 °C for 3A zeolite) contributes significantly to the energy savings. These findings emphasize the potential of layered adsorption beds in optimizing energy consumption and operational efficiency in industrial natural gas dehydration processes.