PhD Position (5) TW12 - Department of Chemical engineering and technical chemistry, Ghent University

over 2 years ago | Deadline: 2012-04-30 17:00


PhD Position (5)
  • Last application date: 2012-04-30 17:00
  • Department: TW12 - Department of Chemical engineering and technical chemistry
  • Contract: bepaald
  • Degree: MSc in Chemical Engineering or related subject
  • Occupancy rate: 100%
  • Vacancy Type: wp

Job description

Comprehensive kinetic model for gasification of ligno-cellulosic biomass.

Aim

In this project it is the objective to develop and validate a detailed kinetic model for gasification of ligno-cellulosic biomass that enables to determine the influence of biomass composition and process conditions on the  gasification products.

Justification

Gasification of biomass is an important process in the alternative energy realm, due to its ability to provide gaseous fuels or chemicals, e.g. hydrogen or syngas, or liquid fuels after further processing, e.g. by Fischer-Tropsch synthesis. This process may prove to be an important part of the world’s future infrastructure, in particular in remote locations where energy is scarce, and biomass or other renewable feedstocks would be beneficial in a carbon-lean world economy.

Biomass gasification includes the following steps: drying, thermal decomposition or pyrolysis, partial combustion of some gases/char, and gasification of decomposition products. Steam, air or oxygen is supplied as an oxidizing agent, and in addition to gaseous products (CO2, water, carbon monoxide, hydrogen and gaseous  hydrocarbons), small quantities of char, ash, and condensable compounds (tars and oils) are formed. Tar is a complex mixture, including, among others, oxygen-containing 1-ring to 5-ring aromatics and poly-aromatic hydrocarbons. The permissible upper limit of tar in the gas depends on the application and is most stringent for syngas production and gas turbines. Based on the gas/solid contacting mode, gasifiers are broadly divided into three types: fixed or moving bed, fluidized bed, and entrained flow. The fluidized-bed design has proved to be particularly advantageous for gasification of biomass. However, minimization of tar formation is crucial for the proper working of the fluidized bed and the temperature range (800 to 1000°C ) is dictated mainly by the minimization of the agglomeration of ash. Current gasification models cannot predict the product composition at different process conditions. Today even the most advanced kinetic models contain only a limited number of reactions and describe the biomass composition with very limited detail. Accounting adequately for transport limitations during industrial operation also remains a significant challenge.

Program

The research program can be divided in 4 stages:

  • Design a new or modify an existing experimental set-up. It is important that mass and heat transport rates within the solid biomass are potentially faster than the intrinsic chemical kinetics. If transport limitations are irreducible they will have to be accounted for during the experimental data analysis.
  • Characterization of the biomass and identification of the elementary reactions that occur when solid biomass interacts with the oxidant. A sufficiently detailed representation of the starting material is one of the first hurdles that needs to be overcome. The kinetics should distinguish between the roles of oxygen present in the biomass and oxygen from the external oxidant.  The most likely pathways will be based on literature  data.
  • Development of a gasification kinetic model combining the  gas/solid reactions developed in stage 2 with a gas-phase reaction model for the consecutive reactions. Experimental data obtained on an electrobalance set-up with solid biomass samples and on a bench-scale continuous flow set-up with model compounds will be used for establishing the reaction network and estimating the corresponding kinetic parameters.
  • Further refinement and final validation of the gasification network and kinetics.  The combined gasification model from stages 2 and 3 will be further validated (and revised if necessary) against supplementary data focusing on selected solid biomass.
  • Advisors: Kevin Van Geem and Guy B. Marin

    Funding:  Advanced Grant of the European Research Council


    Profile

    PhD Fellowships are available in the following domains:

    • Biomass Conversion
    • Transient Kinetics
    • Metal catalyzed reactions
    • Radical Polymerization
    • Pyrolyis and Steam cracking
    • Computational Fluid Dynamics coupled with kinetics

    Typical activities during a 4 year PhD project:

    • Experimental acquisition of intrinsic reaction rate data.
    • Model construction based on reaction mechanisms and estimation of kinetic parameters by data regression and/or quantum chemical calculations.
    • Scale-up of lab data and simulation of industrial processes by developing and implementing reactor models accounting for transport next to reaction. Development and application of Computational Fluid Dynamics models in that context.
    • Normal duties will apply, including the preparation of scientific reports and publications and assisting in supervising of MSc students.

    Requirements

    Applicants must possess a MSc in Chemical Engineering or related subject and a TOEFL certificate (minimum score of 580(paper)/92(iBT)/237(computer)) or equivalent. Relevant experience in the area of reactor engineering, kinetics, and/or computational chemistry is strongly recommended. Candidates must have a strong mathematical background and be willing to focus on obtaining quantitative rather than qualitative results. Excellent candidates with a PhD in the above domains and willing to spend between 1 and 3 years at LCT can also apply for a postdoctoral fellowship.


    Apply

    Any additional information can be obtained by contacting Guy B. Marin. Any application should enclose a C.V., a one page justification of your interest and at least two references.

    Guy.Marin@UGent.be

    09 264 45 17

     



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