Process control strategies for solar-powered carbon capture under transient solar conditions

Abstract

This paper presents process control strategies commanding the novel solar stripper (So-St) network to effectively regenerate the rich solvent and ultimately replace the conventional desorption unit in the PCC. In this work, the effect of solar heat flux (SHF) is analyzed and categorized by the active control strategy in full synergy with the absorber operation. The mismatch in operation between the two ends of the solvent cycle (absorption vs. desorption) is buffered/regulated by solvent storage tanks. Three original and two combined control scenarios are developed and assessed based on their main controlled output and manipulated input variables. It is found that the lean loading control strategy provides the most consistent absorber operation, reliable CO2 productivity, and desirable thermodynamic regime. This superior performance of lean loading control stems from absorbing a relatively larger SHF range without violating solvent temperature and pressure-drop constraints in the So-St network. In practical applications, it is recommended that lean loading control should incorporate temperature control to monitor solvent temperature and provide appropriate remedy control actions when required. Such process control strategies can lead to effective operation of the “solar-powered” carbon capture (SP-PCC), allowing SP-PCC technology to be installed and operated independently and autonomously from the power plant, thus cutting the capture energy penalty by integrating renewable solar heat.