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THERMODYNAMIC PROCESS SIMULATION OF THE DIGESTION UNIT IN IRAN ALUMINA REFINERY
Mälardalen University, School of Business, Society and Engineering.
Mälardalen University, School of Business, Society and Engineering.
2009 (English)In: Proceedings of SIMS 50, Modeling of Energy Technology / [ed] Brian Elmegaard, Christian Veje, Mads Pagh Nielsen, Tommy Mølbak, 2009, p. 173-178Conference paper, Published paper (Refereed)
Abstract [en]

Jajarm bauxite is of the chamosite-diasporic type, one of the hardest types of bauxite for alumina production. The Iran Alumina Refinery uses Jajarm deposits and currently operates at 65-70% of its nameplate capacity. Digestion is one of the most important processes in the refinery and has become the main bottleneck in the production. In this paper we study the effect of selected parameters on the behavior of this important section of the refinery using thermodynamic simulation of the digestion unit. The ASTM tables property method was used for vapor streams and the Elec-NRTL property model was used for the global digestion process. The digestion process was simulated with Aspen plus software. The results show good agreement with experimental data. The relationship between the incoming slurry temperature in the first flash tank and the preheater cold stream (slurry into the furnace) temperature and energy consumption is discussed.

Place, publisher, year, edition, pages
2009. p. 173-178
Keywords [en]
Bauxite, Diaspore, Bayer process, Slurry, Alumina digestion, Simulation, Electrolyte NRTL property model
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:mdh:diva-19009ISBN: 978-87-89502-88-5 (print)OAI: oai:DiVA.org:mdh-19009DiVA, id: diva2:621574
Conference
The 50th International Conference of Scandinavian Simulation Society,SIMS 50-Modelling and Simulation of Energy Technology, Fredericia, Denmark, October 7–8, 2009
Available from: 2013-05-15 Created: 2013-05-15 Last updated: 2013-05-31Bibliographically approved
In thesis
1. Thermodynamic process modeling and simulation of a diaspore bauxite digestion process
Open this publication in new window or tab >>Thermodynamic process modeling and simulation of a diaspore bauxite digestion process
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Bauxite ores which originated from separate mines have different characteristics, i.e. each bauxite ore has its own individual specifications. Jajarm bauxite is of the diaspore-chamosite type and its alumina to silica mass ratio is lower than other diaspore ores. Diaspore bauxite digestion in comparison with other bauxite types has more complicated operational conditions and requires higher temperature, pressure and caustic concentration.

 The present study was thus performed on the above mentioned digestion process and include two parts. First, the behavior of some key parameters of the process was experimentally investigated. Second, a simulation model was developed to predict the performance of the process, particularly thermal energy consumption.  The model was validated with several sets of the industrial data and close agreement was found.

 The effects of various trends in pressure drops of the flash tanks on the slurry preheating were analyzed. The results showed that the proposed pressure profile can lead to an increase in the furnace inlet slurry temperature. Alternatively, it can lead to an appreciable decrease in the furnace fuel consumption, which is required for having the existing operating temperature.

 The generated vapor in different stages of the process was determined. A considerable amount of the generated water vapor and thermal energy were lost. The model was further developed to study the effect of using a part of these vapors on heat recovery. The simulation results showed that in the new design, the pre-heater sections can gain 5.71GJ/h additional heat and the fresh slurry temperature increases by 11°C. Therefore, the furnace required energy is reduced by 11.9%.  The new design was implemented in the refinery and according to the energy department report, it has reduced the furnace fuel consumption by 8%, which is around 200kg of natural gas /h less than the earlier condition for every digestion line.

Place, publisher, year, edition, pages
Västerås: Mälardalen University, 2013
Series
Mälardalen University Press Licentiate Theses, ISSN 1651-9256 ; 170
National Category
Engineering and Technology Materials Engineering
Identifiers
urn:nbn:se:mdh:diva-19001 (URN)978-91-7485-113-7 (ISBN)
Presentation
2013-06-12, Lambda, Västerås, 13:00 (English)
Opponent
Supervisors
Available from: 2013-05-16 Created: 2013-05-14 Last updated: 2013-05-31Bibliographically approved

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