Modelling super-equilibrium in biomass gasification with the constrained Gibbs energy method

Petteri Kangas (Corresponding Author), Ilkka Hannula, Pertti Koukkari, M Hupa

    Research output: Contribution to journalArticleScientificpeer-review

    30 Citations (Scopus)


    The biomass gasification process is modelled by utilising constrained thermodynamic equilibrium. The formation of char, tar, ammonia and light hydrocarbons and related syngas composition were described by extending the conventional chemical system with additional immaterial constraints and by defining process-dependent values for these constraints. Six different model structures were evaluated from global thermodynamic equilibrium to fully constrained local equilibrium. When models were validated against gasification setups, it was not necessary to fully constrain the system, as sufficient results were obtained by implementing constraints for char, tar, ammonia, CH4 formation as well as for the amount of carbon in light hydrocarbons. The method was shown to be versatile when it was validated against other gasification setups: by altering the models defining the constraints a new gasification conditions could be simulated. A clear benefit of the proposed method is that the gasification process can be resolved as a restricted partial equilibrium with a single calculation step. Another benefit is that chemical reactions, gasification enthalpy and the states of the system are estimated concurrently.
    Original languageEnglish
    Pages (from-to)86-94
    Number of pages9
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


    • Biofuels
    • computational methods
    • constrained Gibbs energy
    • thermodynamics


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