Biogas upgrading with PZ/MDEA: Pilot demonstration of absorber intercooling, cold solvent split and lean vapor compression
Jens Kristian Jørsboe, Ebbe Hauge Jensen, Søren Holdt Jensen, Peter Wiers, Jakob Karlsson, Isaac Appelquist Løge, Jens Abildskov, Philip Loldrup Fosbøl
Abstract
The amine scrubbing technology enables upgrading of biogas to high purity biomethane. In this study, a mobile amine scrubbing pilot plant is upgrading industrially produced biogas utilizing a solvent consisting of 6 wt% piperazine (PZ) + 39 wt% methyldiethanolamine (MDEA). The aim of this study is to investigate the potential of three advanced process configurations: Absorber intercooling (IC), cold solvent splitting (CSS), and lean vapour compression (LVC), where CSS and LVC are used in combination. In base case operation, the PZ/MDEA solvent requires a specific reboiler duty (SRD) of 3.4 MJ per kg CO 2 . We find that IC increases the CO 2 content in the rich solvent by 20 % and reduces the specific reboiler duty (SRD) to 3.25 MJ per kg CO 2 . The SRD is further reduced to 2.8 MJ per kg CO 2 when combining IC with LVC and CSS. A ProMax model for the LVC system is used to quantify uncertainties and upscaling of the LVC system for PZ/MDEA. By including the compression work for the LVC, it is shown that the LVC configuration increases the overall energy consumption in the pilot scale experiments.