Showing papers by "Bernt Lie published in 2009"

Oxygen Effects in Anaerobic Digestion

Abstract: Free oxygen effects in bio-gasification are not well known, apart from the common understanding of oxygen being toxic and inhibitory for anaerobic micro-organisms. Some studies have, however, revealed increased solubilisation of organic matter in the presence of some free oxygen in anaerobic digestion. This article analyses these counterbalancing phenomena with a mathematical modelling approach using the widely accepted biochemical model ADM 1. Aerobic oxidation of soluble carbon and inhibition of obligatory anaerobic organisms are modelled using standard saturation type kinetics. Biomass dependent first order hydrolysis kinetics is used to relate the increased hydrolysis rate with oxygen induced increase in biomass growth. The amended model, ADM 1-Ox (oxygen), has 25 state variables and 22 biochemical processes, presented in matrix form. The computer aided simulation tool AQUASIM 2.1 is used to simulate the developed model. Simulation predictions are evaluated against experimental data obtained using a laboratory batch test array comprising miniature anaerobic bio-reactors of 100 ml total volume each, operated under different initial air headspaces giving rise to the different oxygen loading conditions. The reactors were initially fed with a glucose solution and incubated at 35 ‰ for 563 hours. Under the oxygen load conditions of 22, 44 and 88 mg/L, the ADM1-Ox model simulations predicted the experimental methane potentials quite adequately. Both the experimental data and the simulations suggest a linear reduction of methane potential with respect to the increase in oxygen load within this range.

Modeling, Identification and Control at Telemark University College

Abstract: Master studies in process automation started in 1989 at what soon became Telemark University College,and the 20 year anniversary marks the start of our own PhD degree in Process, Energy and Automa-tion Engineering. The paper gives an overview of research activities related to control engineering atDepartment of Electrical Engineering, Information Technology and Cybernetics.Keywords: modeling, simulation, identi cation, control, sensor technology 1 Introduction The Norwegian research journal MIC was initiated bylate Professor Jens Glad Balchen, with the rst issuepublished in 1980. MIC has played a central role inNorwegian cybernetics research, as it coincided with adramatic growth in the number of PhD students andgave these an arena to publish. Telemark UniversityCollege (HiT) salutes the journal, and those who madethe journal possible.The master studies in engineering at HiT started in1988, and the initial board was led by Finn Lied andincluded Inge Johansen and Sven G. Terjesen, all cen-tral people in the engineering community of Norwayin the last part of the 20th century. The leader of theengineering studies was May-Britt Hagg, now professorat The Norwegian University of Science and Technol-ogy (NTNU). In 1989, a study in Process Automationstarted; this study was planned by Terje Hertzberg,Steinar Sˆlid, Gudolf Kjˆrheim, Sven G. Terjesen,Ivar Loe, Jens I. Ytreeide, and Rolf Ergon. Later,Ytreeide became professor in these studies, while Loewas adjunct professor for many years. The Process Au-tomation study was led by Rolf Ergon, now professoremeritus. In 1994, these studies became part of HiT,organized under Faculty of Technology (HiT-TF).From the start, the MSc studies in Porsgrunn hadtheir accreditation from the Ministry of Education andResearch, while the PhD study was formally a degreeat NTNU, where HiT-TF operated almost as a facultyunder NTNU. In April 2009, the Ministry of Educa-tion and Research gave HiT the right to give our ownPhD-degree, in Process, Energy, and Automation En-gineering.The current MSc studies are in Process Technol-ogy, Systems and Control Engineering, and Energyand Environmental Technology, and they are taughtin English. Initially, the strong position of the re-gional process industry shaped the process automationstudy, which had a strong emphasis on modeling of dy-namic systems, numeric methods, process chemistry,separation technology, thermodynamics, etc. Controlengineering was also important, with topics in multi-variable control, optimal and predictive control, stateestimation, and control structures for industrial pro-cesses. Instrumentation technology and process safetywere core topics, and laboratory exercises widely used.With a compact group of teachers in close touch withthe students, this enabled necessary changes in pacewith the developments in the regional and nationalindustry, and today, the core topics are modeling ofdynamic systems, model based control, model based

Model uncertainty and control consequences: a paper machine study

Abstract: Deterministic and statistical descriptions of parametric model uncertainties are discussed and illustrated with a case study from the paper industry. Prediction uncertainties under open loop and closed loop operation are then studied. The results illustrate the importance of a realistic description of parametric uncertainties, and also how closed loop operation can reduce the prediction sensitivity due to parameter uncertainties.

A model for abatement of co2 emissions by de-absorption with monoethanolamine

Abstract: into monoethanolamine(MEA) by chemical absorption is presently the most favored method for the cap-ture of carbon dioxide from fossil fuel combustion. A benefit of chemical absorp-tion into amine solution is that at higher temperatures the chemical reaction can bereversed and the MEA recycled.The majority of previous work on amine CO