P. Ollero

The CO2 gasification kinetics of olive residue

Abstract Orujillo , sometimes called wood matter from pressed oil-stone (WPOS) is a residue from the olive oil mill industry. The generation of this biomass residue is concentrated in small areas allowing its use as fuel for medium size gasification and combustion plants. Rates of gasification of WPOS char were measured in a TGA at various temperatures (800–850–875–900–950°C), CO 2 partial pressures (0.20–0.35– 0.50 bar ) and CO partial pressures (0.0– 0.20 bar ). The experiments were carried out with a monolayer bed of very fine particles well exposed to the gas so as to minimise mass and heat transfer resistances. Two kinetic models, the n th order model and Langmuir–Hinshelwood model, have been used to fit with the reactivity data. For pure CO 2 experiments the kinetic parameters of n th order model were E=133 kJ/mol and n =0.43. The Langmuir–Hinshelwood kinetic model clearly describes the observed CO inhibition effect on the CO 2 gasification.

The drying of alpeorujo, a waste product of the olive oil mill industry

Alpeorujo is a waste product of the olive oil mill industry that still has a significant oil content. Before extracting the remaining oil with hexane, the moisture content of the wet waste product has to be reduced from approximately 65% to about 8%. To develop standards for dryer design and operation, an extensive study was carried out at laboratory scale. A drying tunnel was built to calculate drying curves, volatile emissions, ignition temperatures, and solids degradation at high temperatures while drying under several different operating conditions. The results of this experimental work allowed us to develop a useful drying model for designing new dryers and for assessing the behaviour of existing ones.

Catalytic Seawater Flue Gas Desulfurization Model

A model of a seawater flue gas desulfurization process (SFGD) where oxidation of the absorbed SO(2) is catalyzed by activated carbon is presented. The modeled SFGD process is comprised of two main units, an absorption packed scrubber, where SO(2) absorption takes place, and an oxidation basin, where the absorbed SO(2) is catalytically oxidized to sulfate, a natural component of seawater. The model takes into account the complex physical-chemical features of the process, combining mass-transfer, kinetics and equilibrium equations, and considering the electrolyte nature of the liquid phase. The model was validated with data from a SFGD pilot plant and a sensitivity analysis was performed, showing its predictive capability. The model is a useful tool for designing industrial desulfurization units with seawater.

A pilot plant technical assessment of an advanced in-duct desulphurisation process

In-duct sorbent injection (DSI) is a well-known, low-cost desulphurisation technology handicapped by its moderate SO(2) removal capacity. Fortunately, there are some technical options for increasing the desulphurisation efficiency without eliminating its inherent advantages. In this experimental study, several improvement design options like the recirculation of reactivated sorbent, the pre-collection of the fly ash and the use of seawater for humidification have been analysed using an extensive parametric testing programme. The effect of the main operating variables directly related to the desulphurisation efficiency has been also tested following a fractional factorial design. These variables were the Ca/S ratio, the approach to the adiabatic saturation temperature and the recirculation ratio of the partially converted sorbent. Other important questions like the use of a high-BET-area lime and the impact of the DSI process on an ESP have been also included in this experimental assessment. More than 50 experimental tests were carried out in a 3-MWe equivalent pilot plant to assess the different improvement options for in-duct sorbent injection. The results of this study allow us to extract practical conclusions about the devices, equipment and operating conditions as a function of the target SO(2) efficiency, and even enable us to provide an economic assessment. Using the proposed improvement options to process a flue gas with 400-1000ppm of SO(2) concentration, a 90% sulphur removal with a lime utilisation of 45% was achieved.

A technical pilot plant assessment of flue gas desulfurisation in a circulating fluidised bed

Abstract Flue gas desulfurisation in a circulating fluidised bed absorber (CFBA) is quite a novel dry desulfurisation technology [6th International Conference on Circulating Fluidised Beds (1999) 601] that shows significant advantages in comparison with other dry technologies and that could also be competitive with the widely-used wet FGD technology. This experimental study analyses the performance of a flue gas treatment plant comprising a CFBA and an electrostatic precipitator (ESP). The most significant aspects considered in this study are: the effect of precollecting the fly ash, the effect of the SO2 inlet concentration, the effect of power plant load changes, the contribution of the final particulate control equipment to the overall SO2 removal efficiency and the impact of the desulfurisation unit on the ESP behaviour and its final dust emissions. In addition, the behaviour of the integrated CFBA-ESP system with respect to the main operating parameters was studied by means of a fractional factorial design of experiments. All this experimental work was carried out in a 3-MWe equivalent pilot plant that processes real gases withdrawn from the Los Barrios Power Plant. Processing a flue gas with up to 2000 ppm SO2 concentration, a sulfur removal of 95–97% with a lime utilisation of 75% was achieved. A simple regression model to evaluate the efficiency of the whole system is also proposed.

Modeling and simulation of parabolic trough solar fields with partial radiation

This paper focuses on the modeling and simulation of parabolic trough solar fields in situations of partial covering of the solar field by clouds. In these situations incident solar radiation on the field is different for each loop of it, so it is necessary to model a field that takes into account this radiation distribution. Then, the effect of passing clouds has been studied in order to show how the cloud affects the outlet temperature of this field. Afterwards two control strategies have been described and simulated to test their behavior against situations of partial radiation. Finally, these results have been shown, commented on, and followed to a set of conclusions.

Effect of mixing bio-oil aqueous phase model compounds on hydrogen production in non-catalytic supercritical reforming

Bio-oil derived from biomass fast pyrolysis can be processed into fuel or some chemical products, but it has a waste aqueous phase that, however, may be valorized. Supercritical reforming of this stream, simulated using mixtures of model compounds (acetic acid, acetol, 1-butanol and glucose), was experimentally studied in a tubular reactor without using a catalyst. The effect of mixing the model compounds at different operating parameters (temperature, feed composition, and residence time) on the process performance was investigated, thus addressing an important chemical aspect of biomass-based renewable energy. The experimental dry gas composition consisted of H2, CO2, CO and CH4, although the gas yields were far from equilibrium. Hydrogen yields were normally less than 2.0 moles of H2 per mole of organic feed, which are lower than those obtained for pure compounds with the same concentration. Based on the analyzed liquid samples, a series of probable reaction pathways were proposed to explain the experimental results by considering the interactions among the compounds and their formed intermediates. Thus, under tested supercritical conditions, the residence time was insufficient to reform the formed methane into hydrogen, thus leading to lower hydrogen production.