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An extension of the Barnes' method for the numerical evaluation of the Jacobian matrix of N functions of N variables is presented. It concerns the updating of sparse matrices and/or of matrices with a great number of partial derivatives which can be easily obtained analytically.

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The Chilled Ammonia Process is a mature post-combustion CO2 capture process. The formation of solids in the process at high CO2 and NH3 concentrations was already described in the original patent, but is relatively poorly understood and difficult to explore experimentally. Thermodynamic properties that complicate the experimental investigation, such as the high vapor pressures of CO2 and NH3 and the resulting incongruent solubility as well as the fast decomposition of the solids, are discussed in this work. Preliminary results for the metastable zone width and for nucleation kinetics in the ammonium bicarbonate/water system are presented. The solubility of ammonium bicarbonate derived from dissolution experiments is close to the historical literature values and an explanation for the slight deviation is discussed., Energy Procedia, 63, ISSN:1876-6102, 12th International Conference on Greenhouse Gas Control Technologies, GHGT-12

The CARMA project investigated the potential of Carbon dioxide capture and storage (CCS) in Switzerland and the country-specific difficulties on the way to implementation. CCS may play a major role in the future Swiss energy scenario as a bridging technology between the phase out of nuclear energy and the establishment of an entirely renewable energy system. The key findings of the CARMA project with respect to CCS implementation are summarized. A pilot CO2-injection test on a small scale is proposed to prove the suitability of the considered geological formations for durable and safe CO2 storage, and to gain information about the deep Swiss subsurface. Furthermore, such a field test would support the development of the legal framework needed for CCS and initiate knowledge transfer to the Swiss public. The successful test site in Ketzin, Germany adapted to the Swiss context can serve as a role model., Energy Procedia, 37, ISSN:1876-6102, GHGT-11 Proceedings of the 11th International Conference on Greenhouse Gas Control Technologies

Crystal Growth & Design, 20 (1), ISSN:1528-7483, ISSN:1528-7505

Low-carbon (green) hydrogen can be generated via water electrolysis using photovoltaic, wind, hydropower, or decarbonized grid electricity. This work quantifies current and future costs as well as environmental burdens of large-scale hydrogen production systems on geographical islands, which exhibit high renewable energy potentials and could act as hydrogen export hubs. Different hydrogen production configurations are examined, considering a daily hydrogen production rate of 10 tonnes, on hydrogen production costs, life cycle greenhouse gas emissions, material utilization, and land transformation. The results demonstrate that electrolytic hydrogen production costs of 3.7 Euro per kg H-2 are within reach today and that a reduction to 2 Euro per kg H-2 in year 2040 is likely, hence approaching cost parity with hydrogen from natural gas reforming even when applying "historical" natural gas prices. The recent surge of natural gas prices shows that cost parity between green and grey hydrogen can already be achieved today. Producing hydrogen via water electrolysis with low costs and low GHG emissions is only possible at very specific locations nowadays. Hybrid configurations using different electricity supply options demonstrate the best economic performance in combination with low environmental burdens. Autonomous hydrogen production systems are especially effective to produce low-carbon hydrogen, although the production of larger sized system components can exhibit significant environmental burdens and investments. Some materials (especially iridium) and the availability of land can be limiting factors when scaling up green hydrogen production with polymer electrolyte membrane (PEM) electrolyzers. This implies that decision-makers should consider aspects beyond costs and GHG emissions when designing large-scale hydrogen production systems to avoid risks coming along with the supply of, for example, scarce materials., Energy & Environmental Science, ISSN:1754-5692, ISSN:1754-5706

The near-equilibrium dissolution kinetics of partially dehydroxylated lizardite was investigated at conditions relevant for ex situ CO 2 mineralization, namely 30 ° C ⩽ T ⩽ 90 ° C and p CO 2 1 atm . Batch experiments were carefully designed to explore a wide range of operating conditions without precipitating any secondary phases, namely amorphous silica or magnesium carbonates. The operational range included solutions whose compositions were very close to solubility of the dissolving silicate species. Expressions for specific dissolution rates were developed in order to describe the experimentally measured near-equilibrium, non-steady state dissolution profiles. The near-equilibrium kinetic model was able to describe the evolution of the concentration profiles of Mg ( aq ) and SiO 2 ( aq ) with good accuracy. A small enhancement in the dissolution rates of forsteritic silicate was observed in the presence of high concentrations of bicarbonate ions. The presence of Mg 2 + ions and SiO 2 ( aq ) in the solution were found to affect the specific dissolution rates of the different silicate species present in dehydroxylated lizardite.

The separation of various mixtures of the C 5 -C 6 paraffin fraction is considered, being an important stage of the process aimed to gasoline octane enhancement. The separation is carried out in a six-port vapor phase SMB pilot plant operated at 448 K and 350 kPa, using n-heptane as desorbent and 5A-zeolite as adsorbent. The experimental runs deal with the separation of both a binary mixture (70% isopentane and 30% n-pentane) and a multicomponent C 5 -C 6 stream. The results of these experiments illustrate the role and the effect of the different operating parameters on the process performance and demonstrate the possibility of achieving high performance separation. Moreover, they nicely assess the reliability of the known criteria for selecting robust and optimal operating conditions for SMB units.

This paper investigates different design strategies and process layouts for upgrading crude synthetic natural gas (SNG) produced from lignocellulosic biomass to grid quality. The design problem is outlined by studying the involved key aspects with respect to the crude composition, purity requirements and process integration. A discussion of candidate technology identifies multistage membrane processes as a promising option, for which a multicomponent thermo-economic design model is coupled to a process model for SNG production. In a design study using multi-objective optimisation, the most promising membrane configurations are identified and optimised with respect to cost and efficiency. Comparing design strategies that consider different levels of process integration, it is shown that coupling the reactive and separation sections improves the process design. If process integration is not considered, the separation system is oversized by up to 60% and its investment cost is up to 46% too high. In the last part of the paper, the by-production of biogenic CO2 at sufficient purity for storage is investigated, which would turn the process into a CO2-sink for the atmosphere. The cost of captured CO2 is assessed between 15 and 40 EUR/ton, which makes it potentially more advantageous than the capture at a fossil fuel power plant.

The size and shape of particles crucially influences the characteristics of solid products. Until recently these quantities were evaluated using light microscopy. However, extracting the three-dimensional shape of a faceted crystal from a single image is a formidable computer vision challenge. In this work we combine stereoscopic imaging devices (e.g., commercial stereoscopic microscopes or the stereoscopic flow through cell that continuously draws samples from a crystallizer (Schorsch et al., 2014)) with a model-based approach in which parametric polytopes are used to describe faceted crystals (Hours et al.,2014). In the shape reconstruction algorithm these parametric polytopes are scaled and rotated until their projections closely match the measured stereoscopic images, which is formulated as a nonlinear optimization problem. The proposed approach is assessed using simulated images and experimental data. We also assess in which cases the proposed approach does or does not provide advantages over concepts using generic particle shapes (Schorsch et al., 2012).

The chromatographic separation of Troger's base enantiomers with ethanol as eluent on microcrystalline triacetate cellulose (CTA) was studied. Binary competitive adsorption equilibrium data measured were interpreted using ideal adsorbed solution and real adsorbed solution (RAS) theory. Both models were used to simulate a set of column breakthrough experiments. The competitive behavior of the two enantiomers is quantitatively discussed and the reliability of the two models is assessed. The results show that the RAS model can describe with good accuracy the complex competitive adsorption behavior exhibited by the CTA/Troger's base model system. This conclusion is expected to apply to the adsorption of the other enantiomeric mixtures on chiral stationary phases.

Carbon fibers are studied using digital holographic sequences. Fibers have distinct orientation in space. An algorithm to identify the orientation and the size of suspended fibers from the digitally recorded holographic sequences is presented.

International audience; Quantification of the overlapping particles in crystallization processes is very important for the quality control of chemical products or drugs. We present a method of segmentation of polygonal-shaped (i.e., rectangles, regular/irregular prisms) and overlapping particles from in situ images during a crystallization process for measuring their size distributions. The method is first based on detecting the geometric features of the particles identified by their salient corners. A clustering technique is then applied by grouping three correspondent salient corners belonging to the same particle. The proposed method is applied on particles of ammonium oxalate during batch crystallization in pure water. The particle size distributions are calculated, and a quantitative comparison between the proposed method and a manual sizing is performed. The method showed that it is valid for analyzing the crystal growth, and the results are promising for monitoring the particle size distribution

International audience; Hindering effects of impurities on the crystal growth are usually assumed to result of the adsorption of impurity species on the crystal surface. In the presence of impurities the growth rate does not depend on supersaturation only, but also on the concentration of impurities and on the time a given particle spent in contact with inhibiting species (unsteady-state adsorption mechanisms). Few kinetic models describe such phenomena. Moreover, published models are derived from data obtained from specific experiments performed on singles crystals, which makes their application to real industrial crystallizers rather questionable. Indeed, for process engineering purposes, the available kinetic inhibition models accounting for the effect of impurities (e.g. Cabrera-Vermilyea or Kubota-Mullin's approaches), have to be evaluated in industrial situations where complex and distributed features of the crystallizing suspensions are involved (e.g. during batch solution crystallization). Population Balance Equations (PBE) modelling offers an invaluable simulation tool for such evaluation. With this aim in view, a comprehensive modelling approach based on in situ continuous and dispersed phase measurements, and specific PBE simulation was developed to represent and better understand the effect of impurities on the development of batch crystallization processes. The cooling solution crystallization of Ammonium Oxalate (AO) in water in the presence of various concentration of Nickel Sulphate was selected as a model system during this study. In situ measurements of supersaturation were performed using ATRFTIR spectroscopy and the CSD was assessed thanks to in situ image acquisition followed by off-line image processing. The experimental results were simulated after estimating crystallization kinetic parameters, including parameters of models describing the inhibiting adsorption of impurity on the growing crystal surfaces. Nonlinear optimization techniques were used to fit the experimental data to the simulated ones.

International audience; The process under study aims at removing dissolved fluorides from effluent waters through the addition of calcium and the precipitation of fluorite in a fluidized bed. In the concept developed at COMURHEX, the effluent is a highly concentrated KOH solution and the calcium is provided as a suspension of portlandite with calcite as an impurity. COMURHEX's target is to achieve an efficient defluorination of KOH solutions prior to recycling and to control the growth of the fluorite grains. Since building a fluorite crystallisation model requires a thermodynamic basis, we started exploring portlandite, calcite and fluorite solubility in concentrated KOH solutions. We are primarily concerned with equilibria in the system Ca(OH)2-CaCO3-CaF2-KOHH2O at temperatures 15 - 35°C in KOH solutions up to 6M (340g/kg). Suspensions and mixtures are prepared in a 3 L stirred reactor under N2 atmosphere and the temperature is varied. Liquid samples are taken from the reactor, filtered, diluted, and analysed by ICP-AES for cations and ionic chromatography for anions, while the solids are washed in ethanol and observed by SEM. In order to choose materials and improve techniques, this work was started with the Ca(OH)2-CaCO3-KOH-H2O subsystem, where solubility data and speciation models are already available from the literature. In this subsystem we experienced the analytical and kinetic difficulties already quoted by other authors. Albeit ICP-AES is very sensitive, Ca analysis is difficult in KOH solutions, because portlandite solubility is low and a matrix effect of potassium weakens the Ca signal, so that its calibration must be performed using KOH solutions rather than conventional (dilute) standards. This problem was overcome by using the standard addition method where the calibrating solutions are prepared at the same KOH concentration as the unknown samples and spiked with increasing amounts of calcium. This method enables the absolute calcium variations to be calibrated and the calcium present as impurities in the KOH parent solution (and thus in the standards) to be evaluated by regression.

International audience; We show that acoustic emission (AE) is a very attractive non intrusive technique for monitoring crystallization processes. AE has been successfully applied in many fields of material sciences and it was also used in the pharmaceutical industry for monitoring various chemical engineering processes including fluidized bed granulation, fluidized bed coating, powder compaction, etc. However, few studies deal with the use of AE to monitoring crystallization processes. The objective of this work is to evaluate the potential for using acoustic emission to monitor polythermal batch crystallization in the absence and presence of impurities. The basic concept behind AE monitoring of crystallization processes is that the phase transitions occurring during crystallization in solution induce physicochemical changes in the suspension. Such changes release energy and therefore generate acoustic elastic waves propagating in the liquid medium. Furthermore, as crystal particles are generated, the elastic properties of the dispersed phase also change. The latter changes affect the acoustic emission caused by the particle collision impacts and inter-particles and/or particles-wall frictions. The elasticity of crystals and their kinetic energy are also affected by many other properties such as size, shape, hardness, density, uniformity of composition which obviously depend on the presence of impurities during the process. We report preliminary batch solution cooling experiments obtained with the model system Ammonium Oxalate/water (AO) in the presence of Nickel Sulfate as impurity. The experiments are monitored using AE, ATR FTIR measurement of supersaturation and CSD analysis performed thanks to in situ image acquisition. Complex but promising information is obtained thanks to AE monitoring.

International audience; One of the most important environmental issues for decades to come is the treatment of industrial wastewaters containing salts (sulfates, chlorides, sodium, magnesium ...) which can lead to strong perturbations affecting the fauna and flora when highly concentrated at the discharge point. Different processes used to separate the dissolved salts from the liquid matrix may be encountered depending on the nature and the composition of the effluent. One major objective in the R&D sectors of water and environment is to optimize such processes, while another is to promote the treated wastewaters by recycling the cleared liquid phase or reusing some compounds they contain in other production processes. The latter is of great interest, both to limit the amount of waste and to save natural resources including rare metals but also less noble materials whose amount consumed each year is very important, but the one available not unlimited. Gypsum, the most important raw material of plaster's industry, is a rather interesting example from this point of view as world's known resources are estimated at 2.34 billion tons, which roughly represents 25 years of operation. The industry of plaster will therefore meet in the coming decades a decrease in resources for the commodity, especially in some countries where gypsum deposits will eventually become out of reach or completely depleted.

International audience; The solubility of materials is a thermodynamic variable that depends on their chemical composition and with temperature. Solubility is also affected by the pH, by the presence of additional species in the solution, and by the use of different solvents. On electrolyte, the calculation of solubility requires that the mean ionic activity coefficient be known along with a thermodynamic solubility product.

International audience; In the absence of a dedicated control system, industrial crystallizers often perform suboptimally, which is mostly reflected in a low quality product with a wide or multimodal size distribution, undesirable mean crystal size, a sub optimal crystal shape or an unwanted crystal structure. Recent developments in in situ monitoring, modeling and in both modelfree and model-based nonlinear optimal control strategies however enable new opportunities in the design and application of control strategies in practical situations. The workshop provides an overview of the state-of-the-art in the monitoring, modeling and control of industrial crystallization process and illustrates how these recent developments can contribute to better product quality and improved performance of industrial crystallization processes. Program: * In-line sensors and model-based monitoring strategies - Gilles Févotte * Modeling, parameter estimation and validation of process models - Herman J.M. Kramer * Model-free control and design of crystallisation processes - Zoltan K. Nagy * Optimal Operation of Industrial Batch Crystallizers -Ali Mesbah Topics discussed: In situ monitoring of process variables, model based sensor technologies, population balance modeling, parameter estimation, design of experiments, scale-up, model-free crystallization control (supersaturation and direct nucleation control), optimal operation and control, output feedback nonlinear model based control Who should attend: the workshop is dedicated to PhD students, researchers and industrialists, who are interested in the theory and practice of modern crystallization monitoring and control technologies, exemplified with recent case-studies presenting the implementation of these approaches from laboratory to industrial scale.