P. De Filippis

Transesterification processes for vegetable oils : a simple control method of methyl ester content

One of the main problems in the study or industrial application of transesterification processes for vegetable oils is how to measure the methyl ester content. In this work, a quick analytical method was developed for assessing the methyl ester content of purified “fuel grade” transesterification products by applying a simple correlation with viscosity. The correlation was tested on a wide range of samples with various methyl ester contents; the results were in agreement with the values measured by gas-chromatographic analysis. In a defined range of weight fractions the correlation allows for the determination of the methyl ester content of purified transesterification products by a single viscosity measurement. This method is especially suitable for process control purposes as it determines the methyl ester content quickly and simply.

Gasification process of wastes containing PVC

Abstract Solid waste, in dealing with the growing presence of organic compounds, especially plastics, can be considered an important source of energy since they are inexpensive and easily obtainable materials. However, the presence of polyvinyl chloride (PVC) in the waste can result in a recycling problem when thermal treatment is involved. This work shows the possibilities of recovering energy from waste containing PVC by a gasification process without additional dechlorination facilities. Experimental data obtained in a bench scale two-stage reactor indicate that the addition of Na2CO3 in a blend containing refuse-derived fuel (RDF) and PVC is efficient in eliminating chlorine from the produced off-gas. On the contrary, the less expensive calcium compounds do not show a satisfactory chlorine removal. A thermodynamic simulation of the process substantially leads to the same results. Starting from this study, the working conditions for gasifying waste blends containing PVC in a scaled-up two-stage reactor can be predicted. According to the simulation, the obtained syngas shows that the polluting compounds content is lower than the Italian law limit. As a consequence, it can be used directly to obtain electric power and/or local heating.

Improving the ageing resistance of straight-run bitumens by addition of phosphorus compounds

Abstract The effect of the addition of small quantities (1 wt%) of phosphoric or polyphosphoric acid and other phosphorus compounds on the physical and chemical characteristics of straight-run (distillation) bitumens was studied. The effect was similar to that induced by a mild blowing process: the peptized material increased, with a shift towards a gel structure, and minor effects on penetration and low-temperature properties were observed. The resistance to ageing measured by the RTFO test was greatly increased, indicating a way of improving the ageing resistance of straight-run bitumens. Besides the lower cost, an advantage of such a process over blowing is the fact that the original bitumen specifications are not dramatically affected; moreover, the low-temperature behaviour is not modified.

Removal of PCBs from mineral oils

Abstract The paper deals with the elimination of PCBs from dielectric and contaminated lube oils by using the KPEG process. Experimental runs at lab scale showed that the treatment is effective on both kinds of oils, but the degree of PCBs removal is higher in case of dielectric oils. The PCB elimination grade is affected by both KOH/PEG and PEG/oil ratios, and strongly by the nature of the PCB mixture. In fact, the reactivity of less chlorinated PCBs, i.e. with 3–5 chlorine atoms, is two orders of magnitude lower than that of PCBs with 5–7 chlorine atoms.

Thermal hazard in a batch process involving hydrogen peroxide

Abstract Hydrogen peroxide is a versatile and interesting reagent for many industrial processes; nevertheless, it is very sensitive to impurities that can catalyze its decomposition, so that the desired reaction could be accompanied by undesired parallel and consecutive reactions. As an example, the butadiene free radical polymerization with hydrogen peroxide in the presence of an organic solvent was studied. Batch polymerization occurs in the liquid phase at about 120 °C. Because of the involved reactive compounds and the relatively high temperature, this is an intrinsically dangerous reaction. Therefore calorimetric data can give important information about safety and process optimization during the scale-up. The aim of this research project was to study the influence of impurities on the overall heat of reaction. The experiments were made in a high-pressure reaction calorimeter. The study has revealed that impurities do indeed affect the reaction course. Most importantly, the presence of carboxylic acids and/or ionic iron must be avoided and the recycle of unreacted reagents must be carefully controlled to minimize the build-up of these impurities.

Sulphur-extended asphalt: reaction kinetics of H2S evolution

Abstract The interest in sulphur-asphalt mixtures was especially high in the 1970s and 1980s. At present, there is concern about the behaviour of sulphur-extended asphalts (SEA) because of the problems that could arise during the recycling of old SEA pavements. This paper studies the kinetics of H 2 S evolution during the reaction of sulphur with asphalt; such a reaction starts well below 150°C, as previously stated. The activation energy and the reaction order are different for various types of material: for cracked bitumens the reaction order is 0.5, while for straight-run products it is higher and dependent on the type of bitumen. The results of the study suggest operating with great caution when heating SEA mixtures.

REACTION OF VISBREAKER BITUMENS WITH SULFUR

ABSTRACT The utilization of sulfur in bituminous binders started many years ago: a number of roads were paved in U.S. with SA (sulfur-asphalt) mixtures. Literature reports that, when mixing sulfur and asphalt, H2S evolution starts at temperatures higher than 150°C. By using thermal analysis techniques, the present paper shows that H2S evolution begins at about 130°C for most types of bitumens. Kinetics of reaction between sulfur and visbreaker bitumens were also studied: the reaction order with respect to sulfur is equal to 0.5 for the three visbreaker bitumens considered in this work.

AN INTEGRATED PROCESS FOR STABILIZATION AND UPGRADING OF RESIDUES AND BITUMENS

A three step process is proposed for stabilizing thermal residues and bitumens, such as visbreaker residues, and for upgrading SR bitumens used to produce stable polymer-modified bitumens. The process is based on the addition of phosphorus compounds such as phosphoric or polyphosphoric acid to VB residues and bitumens, and to the utilization of the insoluble by-product for upgrading SR bitumens or for the preparation of very stable polymer modified bitumens.

Reaction of phosphoric acid with thermal residues and bitumens

ABSTRACT The purpose of the work was to study the effect of the addition of small quantities of phosphoric acid (or P2O5), on the physical and chemical behaviour of petroleum residues and bitumens. Phosphoric acid (and P2O5) reacts only with thermal products such as visbreaker (VB) residues and bitumens, and do not react with straight run (SR) products. The unstable constituents of VB residues, i.e. carbonaceous material and part of the asphaltenes, contain significant amounts of free radicals which easily share electrons with phosphorous. The resulting condensed particles are higher molecular wighht, polar material no longher soluble in the bitumen, and flocculate. This reaction confirms the presence of stable free radicals in thermal bitumens and residues, suggests a way to neutralize their destabilizing effect.

Waste Gasification In An Up-draft Fixed-bedGasifier: Experimental Study AndModel Validation

Gasification has been identified as a key technology to enhance the environmental tolerability of low quality fuels such as waste and biomass. In this work the performances of a laboratory scale gasification process fed with waste are reported. Among the several technical choices, we selected the up-draft fixed-bed gasifier as an interesting solution for heat generation in small-scale applications, due to the characteristics of simple geometry and low cost. The experimental setup is composed by an up-draft gasifier followed by a reactor used as filter to remove the particulate and as second thermal and catalytic stage to convert the produced tar in lighter species. A literature model has been adapted to the case under study to analyse the influence of operative parameters such as oxidant flow rate (equivalent and air/steam ratio values) and gasification temperature of the process. The original literature model considers the species gas evolution along the axial coordinate only, and does not include time dependency. To make the model time dependent, the consumption time of the gasification fuel bed estimated from experimental tests was introduced. Since the oxidation zone is below the gasification one, the initial species concentrations were set as the species concentrations produced at the end of the oxidation zone, calculated with an atom mass balance considering a complete char combustion. Since the model concerns only the gasification, the up-draft process was split into two consecutive steps to allow direct comparison between experimental and simulated data: first the drying and pyrolysis processes and then the fixed bed gasification. The model was successfully validated with experimental data and then it was used to predict the operative parameters that determine the optimal syngas composition. The best syngas composition (35% Waste Management and the Environment VI 113 www.witpress.com, ISSN 1743-3541 (on-line) WIT Transactions on Ecology and The Environment, Vol 163,