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This work aims to develop a stationary phenomenological model of an industrial steam reforming unit. Unlike the usual approach in literature, the combustion reactions at the furnace are described t...

Water hyacinth (WH, Eichhornia crassipes, ’Emboch’ in Ethiopia) is a highly disturbing class of invasive and noxious aquatic plants found worldwide in other water bodies and as such is a prime problem in Lake Tana. One approach to successfully control the rapid invasion of WH is to utilize it as a feedstock to produce high-valued commodities in a biorefinery framework. Preliminary life cycle analysis carried out in the study shows that WH biomass is a competitive feedstock for biorefinery systems with a unit cost at $ 24.40 per ton of dry matter. Based on the annual generation capacity of 0.71 million tons of dry mass in lake Tana and following the standard biorefinery process protocols, the predictions indicate that the economic potential of converting WH biomass into 38.8 billion liters of biomethane alone to be at $ 38.8 million, 74.2 million liters of bioethanol alone at $ 51.9 million, and o.52 million tons organic agro-fertilizer alone at $ 130.5/78.3 million as a partial substitute for Anhydrous Ammonia or Muriate of Potash (MOP) fertilizers. Hence the integrated WH management and utilization as a biorefinery feedstock ranks it among the world’s most competitive feedstocks with attractive socio-economic and environmental benefits.

Catalyzed chemical reactions inside tubular reactors play a key role in steam methane reforming process, as they define the temperature and composition profiles of the reformer and, consequently, its efficiency. Although the kinetic modeling of reforming reactions has already been widely discussed, studies that carry out the comparison between kinetic reform models are still scarce. In this context, this work aims to evaluate the influence of different kinetics on the stationary behavior of industrial reformer. The kinetic models of Singh and Saraf (1979), Numaguchi and Kikuchi (1988), Xu and Froment (1989a), and Hou and Hughes (2001) were analyzed and compared with each other. All models describe the reformer satisfactorily with relative deviations around 3.5% compared to experimental and literature data. The results show that the simplest kinetic models present advantages compared to traditional models, such as Xu and Froment (1989a), which is widely used without any prior analysis.

The techno-economic feasibility of three biogas utilization processes was assessed through computer simulations on commercial process simulator Aspen HYSYS: HPC (biogas to methanol), BioCH4 (biogas to biomethane) and CHP (biogas to heat & electricity). The last two processes are already used commercially with the aid of subsidy policies. The economic analysis indicates that, without these policies, none of these attain economic self-sustainability due to high overall manufacturing costs. The estimated minimum support cost (MSCs) were 108, 62 and 109 €/MWh for the HPC, BioCH4 and CHP processes, respectively. The model could explain currently practised government subsidies in Italy and Germany. It was seen that the newly proposed HPC process is economically comparable to the traditional CHP process. Therefore, the HPC process is a possible alternative to biogas usage. A support policy was proposed: 50, 66, 158 and 148 €/MWh for available heat, methane, electricity and methanol (respectively); the proposed energy policy results in a 10% OpEx rate of return for any of the processes, thus avoiding a disparity in the production of different products.

In this work (part of a series in which different biomass conversion routes are studied) a novel coupling between gasification and pyrolysis is described: by means of a design parameter (α) biomass is distributed between these two operations. In order to characterize the quality of the syngas produced, simulations are performed with a gasification / pyrolysis simulator, GASDS. Profiles were obtained for oxygen consumption, together with bio-char, syngas and steam production as a function of α. In a further work, an economic analysis shall define optimal design conditions.