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CFD Modeling of Fixed Bed Reactor for Direct Synthesis of DME from Syngas and Carbon Dioxide

Moradi, Fazel | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43438 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Kazemeini, Mohammad
  7. Abstract:
  8. Today, the global environmental restrictions as well as; energy problems have directed researchers toward developing ideas of producing a clean liquid fuel from coal or natural gas as a major research topic. In this regard, a special attention is paid to the dimethyl ether (DME) as a clean material containing 34.8% oxygen possessing enough positive potential to replace the diesel and LPG fuels. One of the most economic routes for producing the DME is known to be the direct conversion of the synthesis gases and carbon dioxide first to the methanol and then its dehydration to the DME. Moreover, the DME is not limited to a particular country or resource area since small reservoirs of natural gas with low cost might be needed to produce it. Thus, it appears that the DME might indeed be the fuel sought after. In the current study therefore; hydrogenation reactions of carbon monoxide and dioxide, methanol dehydration and water gas shift reactions were kinetically considered as the main reaction routes towards producing the DME material. In this venue, a dynamic pseudo homogeneous model in three dimensions was developed in a fixed-bed reactor. For this purpose, a CFD simulation was articulated where the standard k-ε model with 10% turbulence tolerations implemented. Then the concentration and temperature profiles along the reactor were determined. It was revealed that under conditions considered, a two phase physiochemical system under equilibrium existed for which simulations were performed. Ultimately, generated results of the model under appropriate industrial boundary conditions compared with those of the others available in the open literature to verify the model developed. Then, the effects of various operating parameters including the pressure, temperature were examined. The CFD modeling results generated from the present work revealed reasonable agreement with obtained experimental data available in the open literature which considering the complexity of the task performed was rather satisfying. This research ultimately paved down the road towards a rather precise optimization for the direct DME production needed for the large scale operations in fixed bed reactors and finally the optimum temperature and pressure obtain 270°C and 5 bar, respectively.

  9. Keywords:
  10. Direct Synthesis ; Dimethyl Ether ; Three Dimensional Modeling ; Fixed Bed Reactor ; Computational Fluid Dynamics (CFD) ; Operating Condition

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