Modeling and optimization of a utility system containing multiple extractions steam turbines

Complex turbines with multiple controlled and/or uncontrolled extractions are popularly used in the processing industry and cogeneration plants to provide steam of different levels, electric power, and driving power. To characterize thermodynamic behavior under varying conditions, nonlinear mathematical models are developed based on energy balance, thermodynamic principles, and semi-empirical equations. First, the complex turbine is decomposed into several simple turbines from the controlled extraction stages and modeled in series. THM (The turbine hardware model) developing concept is applied to predict the isentropic efficiency of the decomposed simple turbines. Stodola’s formulation is also used to simulate the uncontrolled extraction steam parameters. The thermodynamic properties of steam and water are regressed through linearization or piece-wise linearization. Second, comparison between the simulated results using the proposed model and the data in the working condition diagram provided by the manufacturer is conducted over a wide range of operations. The simulation results yield small deviation from the data in the working condition diagram where the maximum modeling error is 0.87% among the compared seven operation conditions. Last, the optimization model of a utility system containing multiple extraction turbines is established and a detailed case is analyzed. Compared with the conventional operation strategy, a maximum of 5.47% of the total operation cost is saved using the proposed optimization model.

[1]  Tor-Martin Tveit,et al.  Multi-period steam turbine network optimisation. Part I: Simulation based regression models and an evolutionary algorithm for finding D-optimal designs , 2006 .

[2]  C. Chou,et al.  A thermodynamic approach to the design and synthesis of plant utility systems , 1987 .

[3]  João G.S. Fonseca,et al.  Simulation of a thermal power plant with district heating: Comparative results of 5 different codes , 2006 .

[4]  Chonghun Han,et al.  Periodical replanning with hierarchical repairing for the optimal operation of a utility plant , 2003 .

[5]  I. Grossmann,et al.  Synthesis and Operational Planning of Utility Systems for Multiperiod Operation , 1998 .

[6]  D.-J. Kim,et al.  Exergetic and thermoeconomic analyses of power plants , 2003 .

[7]  Antonis C. Kokossis,et al.  Conceptual optimisation of utility networks for operational variations—I. targets and level optimisation , 1998 .

[8]  Pyong Sik Pak,et al.  Characteristics and economic evaluation of a power plant applying oxy-fuel combustion to increase power output and decrease CO2 emission , 2010 .

[9]  Gisela Montero,et al.  Ecotaxes and their impact in the cost of steam and electric energy generated by a steam turbine system , 2006 .

[10]  Thomas Palmé,et al.  Application of artificial neural networks to the condition monitoring and diagnosis of a combined heat and power plant , 2010 .

[11]  Chonghun Han,et al.  Modeling and Optimization of the Condensing Steam Turbine Network of a Chemical Plant , 2006 .

[12]  Sanjay.  Investigation of effect of variation of cycle parameters on thermodynamic performance of gas-steam c , 2010 .

[13]  S. L. Dixon,et al.  Fluid mechanics, thermodynamics of turbomachinery , 1966 .

[14]  Ali Ghaffari,et al.  Steam turbine model , 2008, Simul. Model. Pract. Theory.

[15]  Ignacio E. Grossmann,et al.  A Rigorous MINLP Model for the Optimal Synthesis and Operation of Utility Plants , 1998 .

[16]  Robin Smith,et al.  Design and Optimization of Flexible Utility Systems Subject to Variable Conditions: Part 1: Modelling Framework , 2007 .

[17]  Zhigang Shang,et al.  A transhipment model for the optimisation of steam levels of total site utility system for multiperiod operation , 2004, Comput. Chem. Eng..

[18]  P. Fiorini,et al.  Environmental assessment and extended exergy analysis of a “zero CO2 emission”, high-efficiency steam power plant , 2006 .

[19]  Robin Smith,et al.  Modelling and Optimization of Utility Systems , 2004 .

[20]  Yukikazu Natori,et al.  An industrial application using mixed-integer programming technique: A multi-period utility system model , 1996 .

[21]  Chonghun Han,et al.  Optimal Multiperiod Planning of Utility Systems Considering Discrete/Continuous Variance in Internal Energy Demand Based on Decomposition Method , 2000 .

[22]  I. Grossmann,et al.  Optimal multiperiod operational planning for utility systems , 1997 .

[23]  Silvia A. Nebra,et al.  Improving bioethanol production from sugarcane: evaluation of distillation, thermal integration and , 2011 .

[24]  Martín Picón-Núñez,et al.  Modelling the power production of single and multiple extraction steam turbines , 2010 .

[25]  Karim Salahshoor,et al.  Fault detection and diagnosis of an industrial steam turbine using fusion of SVM (support vector machine) and ANFIS (adaptive neuro-fuzzy inference system) classifiers , 2010 .