Browsing Institutt for prosess-, energi- og miljøteknologi by Author "Tokheim, Lars-André"
Now showing items 21-32 of 32
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Investigation of bubbling behavior in deep fluidized beds at different gas velocities using electrical capacitance tomography
Agu, Cornelius Emeka; Ugwu, Ambrose; Pfeifer, Christoph; Eikeland, Marianne Sørflaten; Tokheim, Lars-André; Moldestad, Britt Margrethe Emilie (Peer reviewed; Journal article, 2019)Deep bubbling fluidized beds have some advantages that make them attractive for industrial applications. Using different powders, this paper investigates the bubbling behavior in deep beds. The results show that bubbles ... -
Kiln process impact of alternative solid fuel combustion in the cement kiln main burner - Mathematical modelling and full-scale experiment
Ariyaratne, W. K. Hiromi; Melaaen, Morten Christian; Tokheim, Lars-André; Manjula, Edirisinghe V. P. J. (Journal article; Peer reviewed, 2014-02)Increased use of alternative fuels in cement kilns is a trend in the world. However, replacing fossil fuels like coal with different alternative fuels will give various impacts on the overall kiln process due to the fuel ... -
Measurement and characterization of biomass mean residence time in an air-blown bubbling fluidized bed gasification reactor
Agu, Cornelius Emeka; Pfeifer, Christoph; Eikeland, Marianne Sørflaten; Tokheim, Lars-André; Moldestad, Britt Margrethe Emilie (Peer reviewed; Journal article, 2019)Gasification of biomass in bubbling fluidized beds can be limited by accumulation of unconverted char particles during the process. The amount of unconverted biomass depends on the residence time of the fuel particles. ... -
Models for Predicting Average Bubble Diameter and Volumetric Bubble Flux in Deep Fluidized Beds
Agu, Cornelius Emeka; Pfeifer, Christoph; Eikeland, Marianne Sørflaten; Tokheim, Lars-André; Moldestad, Britt Margrethe Emilie (Journal article; Peer reviewed, 2018)The average bubble diameter and volumetric bubble flux give indications about the overall bed expansion in a fluidized bed. As these properties depend on the particle properties and fluidized bed regime, their accurate ... -
Numerical modeling of the calcination process in a cement kiln system
Kahawalage, Amila Chandra; Melaaen, Morten Christian; Tokheim, Lars-André (Journal article; Peer reviewed, 2017)The calcium carbonate decomposition into calcium oxide and carbon dioxide is a key process step in a cement kiln. The reaction requires thermal energy input, and pulverized coal is the fuel typically used for this purpose ... -
Optimum feeding rate of solid hazardous waste in a cement kiln burner
Ariyaratne, W. K. Hiromi; Melaaen, Morten Christian; Tokheim, Lars-André (Journal article; Peer reviewed, 2013)Solid hazardous waste mixed with wood chips (SHW) is a partly CO2 neutral fuel, and hence is a good candidate for substituting fossil fuels like pulverized coal in rotary kiln burners used in cement kiln systems. SHW is ... -
Process Simulation of Calcium Looping With Indirect Calciner Heat Transfer
Jayarathna, Chameera K.; Mathisen, Anette; Øi, Lars Erik; Tokheim, Lars-André (Conference object; Peer reviewed, 2015-11-25)In calcium looping (CL), calcium oxide (CaO) is used as a sorbent for carbon dioxide (CO2). The CO2 reacts with CaO to produce calcium carbonate (CaCO3) in a carbonator operating at about 650 °C. The CaCO3 is then sent to ... -
Substitution of coal by refuse derived fuels (RDF) in the precalciner of a cement kiln system
Kahawalage, Amila Chandra; Melaaen, Morten Christian; Tokheim, Lars-André (Journal article; Peer reviewed, 2017) -
The effect of alternative fuel combustion in the cement kiln main burner on production capacity and improvement with oxygen enrichment.
Ariyaratne, W. K. Hiromi; Melaaen, Morten Christian; Tokheim, Lars-André (Journal article; Peer reviewed, 2013)A mathematical model based on a mass and energy balance for the combustion in a cement rotary kiln was developed. The model was used to investigate the impact of replacing about 45 % of the primary coal energy by different ... -
The impact of staged combustion on the operation of a precalciner cement kiln
Tokheim, Lars-André (Doctoral theses at NTNU;1999:89, Doctoral thesis; Peer reviewed, 1999)In this thesis, the impact of staged combustion on the operation of a precalciner cement kiln, is considered. Mathematical modelling and full-scale experiments at the Norcem cement works in Brevik, Norway, is the basis for ... -
Validation of results from Barracuda® CFD modelling to predict the minimum fluidization velocity and the pressure drop of Geldart A particles
Jayarathna, Chameera K.; Moldestad, Britt Margrethe Emilie; Tokheim, Lars-André (Journal article; Peer reviewed, 2017)Fluidization characteristics such as the minimum fluidization velocity and the bed pressure drop are important for the design of an efficient fluidized bed. These characteristics can be measured experimentally, but also ... -
Waste heat availability in the raw meal department of a cement plant
Amarasinghe, Widuramina Sameendranath; Husum, Ida; Tokheim, Lars-André (Journal article; Peer reviewed, 2017)