Faculty Publications

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    Design of Robust PI Controller with Decoupler for a Fluid Catalytic Cracking Unit
    (American Chemical Society service@acs.org, 2019) Prabhu Teja, Y.; Sankar Rao, C.
    In this work, a decoupling control system is designed for the riser section of the fluid catalytic cracking unit (FCCU). The decentralized control system is implemented on FCCU to estimate the magnitude of the interactions using relative gain array (RGA). Interactions among the loops are minimized by applying the decoupling control strategy to decentralized FCCU. Relative normalized gain array and dynamic relative gain array (dRGA) are computed for the closed-loop FCCU and used to design the decouplers for the process. The advantages of the decoupling control strategy are a simple design and it does not need extensive calculations. This method gives a dynamic decoupler in the form of lead/lag modules with time delays. PI controllers can be designed efficiently for controlling the riser temperature, mass fractions of gasoline, and LPG. The decentralized controller and the decoupling control system performances are studied on the basis of the closed-loop performance of control variables, and it is found that the decoupler performs better. © © 2019 American Chemical Society.
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    Robust optimal centralized PI controller for a fluid catalytic cracking unit
    (De Gruyter Open Ltd, 2021) Yadav, G.; Kiran, G.U.; Sankar Rao, C.
    Fluidized Catalytic Cracking (FCC) is a complex process that arises due to feed composition, non-linearities, and dynamic mass and heat interactions in its components. FCC is difficult to model and monitor in industries, and one of the key reasons is that they are multivariable processes. Such processes are highly interacting and that makes the process of controlling even more difficult. The interaction between loops can be quantified easily by dRGA. An easy and effective way of controlling multivariable processes is to implement a centralized control system, considering the interactions between measured and manipulated variables. In this study, a centralized control system is designed for the riser section of the FCC unit. The dRGA method is modified to enhance the closed-loop response by formulating an optimization problem and obtaining an optimal controller settings. A rigorous simulation studies show an 826% reduction in ISE values, a 309% reduction in IAE values, and a 262% reduction in ITAE value of T r i s ${T}_{ris}$ from the dRGA method to the modified dRGA method. Further, IAE values for Y l p g are reduced by 29% from dRGA to modified dRGA method and 34% from synthesis to modified dRGA method. © 2020 Walter de Gruyter GmbH, Berlin/Boston.