Pressurized OCC (oxy-coal combustion) process ideally flexible to the thermal load

A pressurized oxycoal combustion process is optimized for variable thermal loading (100%-30%). The steam expansion line behavior is accurately represented based on manufacturer data. Simulations with the nominal design and nominal operation are then performed with variable loads to determine the level of performance decrease if no optimization is performed. Finally, optimization of operation for a fixed design, and simultaneous optimization of design and operation are performed. The design optimization for a specific load does not include the redesign of the turbines to a process specifically designed for this load. However, the design variables of the turbine expansion line, namely the extraction bleeds, are considered. At each load, the performance of the process designed for nominal load is compared to the maximum possible performance obtained when designing the process for that specific load. Thanks to the thermal recovery section, the process exhibits ideal flexibility to load variations (not accounting for efficiency variations in the air separation unit, hence assuming oxygen storage), unlike Rankine cycles without pressurized recovery. Consequently, there is no need to optimize for an expected distribution of load operations. Finally, the process maintains supercritical working-fluid conditions over larger ranges of thermal loads. (C) 2014 Elsevier Ltd. All rights reserved.