Control Structure Design for CO2‐Absorption Processes with Large Operating Ranges

Coal‐fired power plants are operated flexibly over a large operating range, with variations in flue‐gas mass flow rate and composition. Postcombustion absorption processes are used to separate the CO2 from the flue gas at every operating point in the most economical way. Maintaining an economically feasible operation is the objective of the control structure. In this work the control structures were designed using a self‐optimizing control procedure for two process configurations. The control structures allow for an economic operation with a power‐plant load in the range of 40–100 %. The loss of the designed feedback‐control structures in comparison to an optimized control at every operating point was between 0.57 and 2.64 % in terms of cost of CO2 avoided. Control issues: For the operation of plant‐scale CO2‐absorption processes, control structures are needed which allow for a flexible process and economical CO2 separation over a large range of operating conditions. In this work plantwide control structures are systematically designed using a self‐optimizing control procedure. The control structures enable an economical separation at every operating point.