System-level dynamic models of power plants are valuable tools for the assessment and prediction of plant performance, decisions on the design configuration, and the tuning of operating procedures and control strategies. In this work, the development of an integrated power plant model is presented. This model is validated against steady-state data from a subcritical power plant with reheat and regenerative cycles. The coal-fired power plant model studied has nominal power generation of 605 MW and efficiency of 38.3%. Traditional, regulatory control architectures are incorporated into and tuned with the dynamic power plant model. Dynamic simulation shows that the plant model is stable for sudden changes in coal load, and the controllers are able to maintain the controlled variables at their set points. In this two-part publication, we present the complete workflow of data collection, model development and validation, control tuning, dynamic optimization formulation and solution, and supervisory control architecture for a coal-fired subcritical power plant. Part I focuses on elements of model development and analysis, illustrating the advantages of acausal, objectoriented modeling in power plant simulation. Part II illustrates the use of this model for efficiency optimization under transient part-load operation.

The increasing variability in power plant load in response to a wildly uncertain electricity market and the need to to mitigate CO2 emissions, lead power plant operators to explore advanced options for efficiency optimization. Model-based, system-scale dynamic simulation and optimization are useful tools in this effort and are the subjects of the work presented here. In prior work, a dynamic model validated against steady-state data from a 605 MW subcritical power plant was presented. This power plant model was used as a test-bed for dynamic simulations, in which the coal load was regulated to satisfy a varying power demand. Plant-level control regulated the plant load to match an anticipated trajectory of the power demand. The efficiency of the power plant’s operation at varying loads was optimized through a supervisory control architecture that performs set point optimization on the regulatory controllers. Dynamic optimization problems were formulated to search for optimal time-varying input trajectories that satisfy operability and safety constraints during the transition between plant states. An improvement in time-averaged efficiency of up to 1.8% points was shown to be feasible with corresponding savings in coal consumption of 184.8 tons/day and a carbon footprint decrease of 0.035 kg/kWh.

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Chemical-looping combustion is explored as a chemical reactor design problem. The continuous operation of fixed bed reactors using gaseous fuels for the purpose of power generation through integration with a combined cycle power plant is studied. The fixed bed reactors are assumed to operate in a semibatch mode composed of reactor modules that are integrated into module trains that comprise the chemical-looping combustion island of the power plant. The scheduling of each reactor train is cast as an optimization problem that maximizes thermodynamic efficiency subject to constraints imposed to each reactor and the entire island. It is shown that when the chemical-looping reactors are arranged cyclically, each feeding to or being fed from another reactor, in an operating scheme that mimics simulated moving bed reactors, the thermodynamic efficiency of the reactor island can be improved. Allowing the reversal of module order in the cyclically arranged reactor modules further improves the overall thermodynamic efficiency (to 84.7%, defined as the fraction of enthalpy sent to the gas turbine of a combined cycle power plant over the total energy output of the reactor), while satisfying constraints imposed for carbon capture, fuel conversion, power plant safety, and oxygen carrier stability.

Chemical‐looping combustion (CLC) is a promising and efficient method for power generation with in situ CO2 capture. In this work, we focus on high‐pressure fixed‐bed CLC reactors integrated with combined cycle (CC) power plants. Specifically, the dynamic nature of fixed‐bed chemical‐looping reactors and the many kinetically controlled reactions necessitate the use of dynamic modeling to evaluate power plant performance, efficiency, stability, and feasibility under transient operation. We present a dynamic model for an integrated CLC–CC power plant and transient analyses of the integrated plant performance. A network of dynamically operated fixed‐bed reactors fed with natural gas comprises the CLC plant component. A dynamic model is developed and tuned to match the performance of a commercial combined cycle power plant. The transient variations of the integrated plant in terms of power, temperature, and pressure profiles are presented. The simulation results show that despite the inherent batch‐type operation of the CLC reactor, the operation of the combined cycle is relatively unaffected, and there are small oscillations of approximately 2 % around the desired steady‐state conditions.