Novel BECCS implementation integrating chemical looping combustion with oxygen uncoupling and a kraft pulp mill cogeneration plant

Abstract

Bioenergy with CO2 capture and storage (BECCS) is a promising negative emission technology (NET). When using sustainably produced biomass as fuel, BECCS allows the production of power and heat with negative CO2 emissions. The main technical challenges hindering the deployment of BECCS technologies include energy penalties associated with the capture process. This work evaluates the performance of an advanced CO2 capture technology, chemical looping with oxygen uncoupling (CLOU), replacing a conventional fluidized bed boiler in the power boiler role in a large, modern integrated pulp and paper mill. Results from a MATLAB/Simulink reactor model were incorporated in a plant and integration model developed in a commercial process simulation software to quantify the performance of the CLOU-integrated cogeneration plant. The results show that in this specific application, the typically already low efficiency penalty of CLOU-based carbon capture and storage (CCS) systems could be eliminated entirely, and actually even a very small efficiency gain could be obtained. The highly efficient operation is possible due to the high moisture and hydrogen contents of the biomass and the separation of combustion products and excess air streams in the CLOU process; this provides an opportunity to recover a significant amount of heat by flue gas condensation at a higher temperature level than what is possible in a conventional boiler. Together with abundant low-temperature heat sinks available at the pulp and paper application allows freeing a considerable amount of low-pressure steam for expansion in the condensing turbine. The resulting increase in gross generator output proved enough to not only match, but very slightly exceed the approximately 18 MW parasitic load introduced by the CLOU system in comparison to the conventional boiler.