Modeling and Optimization of a Steam System in a Chemical Plant Containing Multiple Direct Drive Steam Turbines

Steam systems in some of China’s chemical plants usually contain multiple direct-drive steam turbines that provide mechanical power to pumps/compressors. When optimizing this system, a certain degree of deviation is found in the theoretical models of steam turbines. A more realistic steam turbine model is developed by improving the traditional thermal model using industry data. This model characterizes efficiency variations under different conditions. Boiler and other unit models are then simplified to allow the use of this model in optimization. By incorporating the models, a mixed-integer nonlinear programming (MINLP) model is formulated to perform the operation optimization. The proposed model considers electric power as the alternative energy source for lower-level mechanical power demands. Using the proposed optimization model on an ethylene plant, a maximum of 8.01% reduction in the total operation cost is achieved compared with the original operation strategies. This case study shows a successful a...

[1]  Tomio Umeda,et al.  A Thermodynamic Approach to Steam-Power System Design , 1980 .

[2]  Ignacio E. Grossmann,et al.  A structural optimization approach in process synthesis—I: Utility systems , 1983 .

[3]  B. Linnhoff,et al.  The pinch design method for heat exchanger networks , 1983 .

[4]  Gintaras V. Reklaitis,et al.  Computer‐aided synthesis and design of plant utility systems , 1984 .

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

[6]  Bodo Linnhoff,et al.  Total site targets for fuel, co-generation, emissions, and cooling , 1993 .

[7]  Luis Puigjaner,et al.  Targeting and design methodology for reduction of fuel, power and CO2 on total sites , 1997 .

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

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

[10]  Antonis C. Kokossis,et al.  Hardware composites: A new conceptual tool for the analysis and optimisation of steam turbine networks in chemical process industries: Part I: principles and construction procedure , 1998 .

[11]  I. Grossmann,et al.  A Bilevel Decomposition Algorithm for Long-Range Planning of Process Networks , 1998 .

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

[13]  T. Majozi,et al.  Steam System Network Synthesis Using Process Integration , 2008 .

[14]  Yeong-Koo Yeo,et al.  Modeling and simulation of motor/turbine processes in utility plant , 2008 .

[15]  T. Majozi,et al.  Synthesis and optimization of steam system networks. 2. Multiple steam levels , 2010 .

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

[17]  Xianglong Luo,et al.  Modeling and optimization of a utility system containing multiple extractions steam turbines , 2011 .

[18]  Ben Hua,et al.  Improvement on the Simultaneous Optimization Approach for Heat Exchanger Network Synthesis , 2012 .

[19]  Ying Chen,et al.  Heat integration of regenerative Rankine cycle and process surplus heat through graphical targeting and mathematical modeling technique , 2012 .

[20]  Minbo Yang,et al.  Graphical Analysis of the Integration of Heat Pumps in Chemical Process Systems , 2013 .