Automatic load change coordinated control of air separation units

Abstract An automatic load change coordinated control system is developed for strongly coupled and nonlinear air separation units. Firstly, a loosely coupled model is established to solve the tight coupling problem and a robust control strategy integrated with loosely coupled model and priority setting of controlled variables is formed. Secondly, an incremental load balancing calculation method is proposed to handle the nonlinearity and the external target of backflow valve opening is adjusted in real time to solve the hysteresis characteristic. Finally, the comprehensive energy consumption decreases by 2% through deploying the designed automatic control system in an actual air separation unit.

[1]  Christopher L.E. Swartz,et al.  Optimization-based assessment of design limitations to air separation plant agility in demand response scenarios , 2015 .

[2]  Zhijiang Shao,et al.  Simulation and optimization of cryogenic air separation units using a homotopy-based backtracking method , 2009 .

[3]  Xi Chen,et al.  Optimal scheduling of multiple sets of air separation units with frequent load-change operation , 2017 .

[4]  Shu Lin,et al.  Model Predictive Control — Status and Challenges , 2013 .

[5]  Alexander W. Dowling,et al.  A framework for efficient large scale equation-oriented flowsheet optimization , 2015, Comput. Chem. Eng..

[6]  Xinggao Liu,et al.  Nonlinear dynamic behaviors and control based on simulation of high-purity heat integrated air separation column. , 2015, ISA transactions.

[7]  Zuhua Xu,et al.  Automatic load change system of cryogenic air separation process , 2011 .

[8]  Xinggao Liu,et al.  Modeling, Characteristic Analysis and Optimization of an Improved Heat‐Integrated Air Separation Column , 2015 .

[9]  Rolf Isermann,et al.  Identification of Dynamic Systems: An Introduction with Applications , 2010 .

[10]  Xinggao Liu,et al.  An advanced control of heat integrated air separation column based on simplified wave model , 2017 .

[11]  Victor M. Zavala,et al.  Advanced step nonlinear model predictive control for air separation units , 2009 .

[12]  W. Luyben.  Control of a recuperative vapor- recompression air separation process , 2016 .

[13]  Michael Baldea,et al.  Optimal Design of Air Separation Plants with Variable Electricity Pricing , 2014 .

[14]  Michael Baldea,et al.  Optimal Process Operations in Fast-Changing Electricity Markets: Framework for Scheduling with Low-Order Dynamic Models and an Air Separation Application , 2016 .

[15]  Tao Zou,et al.  A steady-state target calculation method based on "point" model for integrating processes. , 2015, ISA transactions.

[16]  Liang Chang,et al.  Dynamic behaviours and control of full tower heat integrated air separation columns , 2015 .

[17]  David Q. Mayne,et al.  Model predictive control: Recent developments and future promise , 2014, Autom..

[18]  Christopher L.E. Swartz,et al.  Dynamic modeling and collocation-based model reduction of cryogenic air separation units , 2016 .

[19]  Tao Zou,et al.  Constrained model predictive control with economic optimization for integrating process , 2015 .

[20]  Alexander W. Dowling,et al.  Equation-oriented Optimization of Cryogenic Systems for Coal Oxycombustion Power Generation☆ , 2014 .

[21]  Carl D. Laird,et al.  Optimal design of cryogenic air separation columns under uncertainty , 2010, Comput. Chem. Eng..

[22]  Xi Chen,et al.  Complete Equation-Oriented Approach for Process Analysis and Optimization of a Cryogenic Air Separation Unit , 2015 .

[23]  Xinggao Liu,et al.  Dynamic behaviors and nonlinear wave model control of heat integrated air separation columns with different purities , 2016 .