Accounting linear program models

Process Design vs. Accounting Linear Program Models... 

In a paper machine heat recovery system (HRS) the exhaust air streams of the paper machine dryer section are utilised for heating different cold streams. Condensation of the air moisture causes strong non-linearities in the system, notably the heat flow rates per °C and the heat transfer coefficients in the exchangers. A mixed integer non-linear programming (MINLP) model has been developed that takes into account these non-linearities (Soderman et al., 1999). Additionally the heat transfer area prices can be given as concave price curves in the model and the climate of the mill location can be taken into account with a multiple period formulation. 

Change the model and program to account for a linear temperature profile. 

The model predictive control used includes all features of Quadratic Dynamic Matrix Control [19], furthermore it is able to take into account soft output constraints as a non linear optimization. The programs are written in C++ with Fortran libraries. The manipulated inputs (shown in cm Vs) calculated by predictive control are imposed to the full nonlinear model of the SMB. The control simulations were made to study the tracking of both purities and the influence of disturbances of feed flow rate or feed composition. Only partial results are shown. 

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