• Changing between Active Constraint Regions for Optimal Operation: Classical Advanced Control versus Model Predictive Control 

      Reyes-Lúa, Adriana; Zotica, Cristina Florina; Das, Tamal; Krishnamoorthy, Dinesh; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)
      Control structures must be properly designed and implemented to maintain optimality. The two options for the supervisory control layer are Advanced Control Structures (ACS) and Model Predictive Control (MPC). To systematically ...
    • Composition Estimation in Dividing-Wall Columns Using Temperature Measurements 

      Ghadrdan, Maryam; Halvorsen, Ivar j.; Skogestad, Sigurd (Conference object; Lecture, 2011)
      In this work, we propose a method to estimate the product compositions in a distillation column section based on a combination of a number of temperature measurements from different locations in ...
    • Control and operation of dividing-wall columns with vapor split manipulation 

      Dwivedi, Deeptanshu (Doctoral Theses at NTNU, 1503-8181; 2013:20, Doctoral thesis, 2013)
      Thermally coupled distillation arrangements with dividing-wall implemen- tation provide significant energy and capital savings compared to energy intensive conventional distillation arrangements. In this thesis, the focus ...
    • Control of Fuel Cells 

      Zenith, Federico (Doktoravhandlinger ved NTNU, 1503-8181; 2007:65, Doctoral thesis, 2007)
      This thesis deals with control of fuel cells, focusing on high-temperature proton-exchange-membrane fuel cells. Fuel cells are devices that convert the chemical energy of hydrogen, methanol or other chemical compounds ...
    • Control of Steady-state Gradient of an Ammonia Reactor using Transient Measurements 

      Bonnowitz, Harro; Straus, Julian; Krishnamoorthy, Dinesh; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)
      This paper presents the application of a steady-state real-time optimization strategy using transient measurements to an ammonia synthesis reactor case. We apply a new method for estimating the steady-state gradient of the ...
    • Control structure design for a CO2-refrigeration system with heat recovery 

      Andreasen, Glenn; Larsen, Lars F.S.; Stoustrup, Jakob; Skogestad, Sigurd (Journal article; Peer reviewed, 2019)
      In this work, we analyze a generic supercritical CO2-refrigeration system with parallel compression, based on systems used for supermarket use. In order to maximize energy efficiency, this system has a “heat-recovery” ...
    • Control Structure Design for Optimal Oparation of 4-Product Thermally Coupled Columns 

      Dwivedi, Deeptanshu; Halvorsen, Ivar j.; Skogestad, Sigurd (Lecture, 2011)
      Control and operation of energy efficient complex distillation arrangements like Kaibel and Petlyuk columns can be challenging. This paper discusses the control structure design for stabilizing ...
    • Control Structure Design for Two Distillation Columns in Sequence 

      Marvik, Tor Anders (Master thesis, 2014)
      Even for simple distillation systems with only two columns, the control problem can be significant. This project provides an initial outline of a systematic procedure for finding the optimal control structure, through ...
    • Controllability Analysis of Ammonia Synthesis Loops 

      Gullberg, Rebecca Maria Brigitte (Master thesis, 2018)
      Present ammonia synthesis loops normally operate under stationary conditions. Generally, ammonia synthesis loops can be slow to ramp up and down due to manual mode operation. Furthermore, load disturbances are not rejected ...
    • Data-driven Scenario Selection for Multistage Robust Model Predictive Control 

      Krishnamoorthy, Dinesh; Thombre, Mandar; Skogestad, Sigurd; Jäschke, Johannes (Journal article; Peer reviewed, 2018)
      A main assumption in many works considering multistage model predictive control (MPC) is that discrete realizations of the uncertainty are chosen a-priori and that the scenario tree is given. In this work, we focus on ...
    • Design and simulation of dividing wall column for ternary heterogeneous distillation 

      Le, Quang Khoa (Master thesis, 2014)
      Heterogeneous azeotropic distillation is routinely used in chemical industry to separate close boiling point mixtures and azeotropes, which are not easily separated in a normal distillation process. Dividing wall column ...
    • Designing packed multi-partition wall dividing wall columns 

      Dejanovic, I.; Matijasevic, L.; Halvorsen, Ivar J.; Skogestad, Sigurd; Kaibel, B.; Jansen, H.; Olujic, Z. (Lecture, 2011)
    • Dividing wall columns for natural gas liquefaction plants 

      Halvorsen, Ivar Johan; Dejanovic, Igor; Olujic, Zarko; Skogestad, Sigurd (Journal article; Peer reviewed, 2018)
      In order to meet current carbon dioxide emissions reduction challenges, natural gas processing and refining industries have to find the ways to minimize energy requirements of distillation operations. Building on foundations ...
    • Dynamic Extremum Seeking Control Using ARX model 

      Ryu, Jeongrim (Master thesis, 2018)
      In the design of the dynamic ESC, a wave perturbation is decided to be not a sinusoidal wave but a pseudo-random binary sequence(PRBS) wave. The reason behind this is that diverse frequencies in the PRBS wave make the ARX ...
    • Dynamic modeling and optimalization of the cheese making procedure 

      Kjellstrøm, Tomas Tungen (Master thesis, 2017)
      This thesis has successfully derived an dynamic model based on analytic solutions for production of semi-hard cheeses on the basis of raw milk from the cattle breed Norwegian red. The main emphasis has been to create a ...
    • Dynamic Simulation of Heat Exchanger with Multicomponent Phase Change 

      Zotica, Cristina Florina (Master thesis, 2017)
      A dynamic model for a heat exchanger with multicomponent phase change, part of reliquefaction cycle of natural gas, is developed. The finite control volume method is used to spatially discretize the heat exchange intro a ...
    • Economic Plantwide Control for a Methanol Plant using Commercial Process Simulation Software 

      Reyes Lua, Adriana (Master thesis, 2014)
      It is desired to make the Economic Plantwide Control design procedure proposed by Skogestad (2000, 2004, 2012) available for engineers without deep knowledge of process control or optimization. The integration of the use ...
    • Energy efficient distillation 

      Skogestad, Sigurd; Halvorsen, Ivar Johan (Journal article; Peer reviewed, 2011)
      Distillation is responsible for a significant amount of the energy consumption of the world’s process industry and also in the natural gas processing. There is a significant energy saving potential that can be obtained by ...
    • Feedback Real-Time Optimization Strategy Using a Novel Steady-state Gradient Estimate and Transient Measurements 

      Krishnamoorthy, Dinesh; Jahanshahi, Esmaeil; Skogestad, Sigurd (Journal article; Peer reviewed, 2019)
      This paper presents a new feedback real-time optimization (RTO) strategy for steady-state optimization that directly uses transient measurements. The proposed RTO scheme is based on controlling the estimated steady-state ...
    • Finding Self-optimizing Control Variables Using Process Data 

      Simonsen, Rannei Solbak (Master thesis, 2014)
      In this project we have studied a newly developed way to find self-optimizing variables. The method studied in this thesis uses data measurements, y, to fit a quadratic cost function. By using parameters found in the cost ...