Abstract:The supercritical water gasification process is an alternative to both conventional gasification as well as anaerobic digestion as it does not require drying and the process takes place at much shorter residence times; a few minutes at most. The drastic changes in the thermo-physical properties of water from the liquid state to the supercritical state make it a promising technology for the efficient conversion of wet biomass into a product gas that after upgrading can be used as substitute natural gas. The earliest research goes back as far as the 1970s and since then, supercritical water has been the subject of many research works in the field of thermochemical conversion of wet biomass. This article reviews the state of the art of the supercritical water gasification technology starting from the thermophysical properties of water and the chemistry of reactions to the process challenges of such a biomass based supercritical water gasification process plant.

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The stability over time of elemental mercury, methylmercury and inorganic mercury species was evaluated in heptane, toluene and mixed hydrocarbon solutions. Elemental mercury and inorganic mercury(ii) were determined using a specific extraction method followed by ICP-MS or CVAAS. Methylmercury and mercury(ii) were determined by GC-MIP-AES after derivatisation with Grignard reagent. The results show that significant losses of mercury species from solution can occur by two pathways: by adsorption on the container wall and by reactions forming mercury(i) compounds. For the latter pathway, rapid losses of dissolved elemental mercury and mercury(ii) chloride species occur when both are present in solution. For heptane solutions containing HgCl 2 , 80% of the HgCl 2 remains after 13 d in a pure standard compared with 11% in a standard containing Hg 0 . Mercury(i) compounds form a colloidal material, which is not soluble in these organic solvents at a detectable concentration. Mercury(i) compounds were butylated with Grignard reagent to form the organic mercury(i) compound (C 4 H 9 ) 2 Hg 2 that was measured specifically by GC-MIP-AES and GC-MS. This new compound was stable and appeared to precipitate from solution.

This study aims to develop a model to predict the formation of compounds during the supercritical water gasification of biomass with a thermodynamic equilibrium approach. A Gibbs free energy minimization routine has been developed using MatLab software to predict the equilibrium state compounds of the system. Regarding all the calculations, pure condensed phases (both liquids and solids), gases, and aqueous compounds (both neutral and ionic species) have been taken into account in the subcritical region, and in the supercritical region, aqueous hydrate complexes have been taken into account instead of the aqueous compounds. The model has been validated for subcritical and supercritical regions separately. A case study for supercritical water gasification of a microalgae feedstock sample has been performed. The effects of temperature, pressure, and dry matter content on the phase behavior of elements and main product gases have also been investigated. The results of this work show that the model developed on the basis of Gibbs free energy minimization involving multiphase compounds can be used to predict the formation of equilibrium state compounds during supercritical water gasification of biomass.

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Most people have problems to understand the scenery of a city using just topographical maps and descriptive city guides. Especially maintaining the route by comparing the current position using the map and to get directions where to go by a written guidance is quite complicated. One possibility to increase the interaction between the map and the user is to use a handheld navigation system, in which a GPS receiver or another kind of locating tool is used to pinpoint the current location of the user in the map display. This approach solves the 'where am I' and 'where to go' questions and even the 'how to get there' problem when supported by a road-database. But the user still has to translate the information projected on the map to the real world and visa versa. This paper addresses a way out of this problem by avoiding the need of map information processing by applying panoramic images as the 'background' layer to display upon certain geometric features, guiding directions, and information labels. The company CycloMedia provides the panoramic images or socalled Cyclorama's. We give some directions how to decide which value-added information can be augmented within the Cyclorama and which not because real world features do obstruct it. General TermsManagement, Measurements, Documentation, Human factors

This study aims to investigate the energetic behavior as well as the behavior of formed gases, taking into account the inorganic content in the supercritical water gasification (SCWG) of microalgae for different process conditions. Two different salt separation cases and different process conditions including varying inorganic content of microalgae have been studied. In addition, the behavior of inorganic elements has been investigated by means of phase partitioning and compound formation in different process equipment of a conceptual SCWG plant. The results show that the process is thermally more efficient when the reactor temperature is lower and when the dry microalgae concentration in the feed is higher. The increase in the mass fraction of the inorganic content of microalgae enhances the formation of CH 4 and H 2 and decreases the thermal energy requirement of the reactor.