J.A. Legarreta

Recycling of the Products Obtained in the Pyrolysis of Fibre-Glass Polyester SMC

An SMC (Sheeting Moulding Compound) of fibre-glass and orthophthalic polyester has been pyrolysed in a 3·5 dm3 autoclave for 30 min in a nitrogen atmosphere at 300, 400, 500, 600 and 700°C. Gas yields of 8–13 weight%, liquid yields of 9–16 weight% and solid residues of 72–82 weight% were obtained. The suitability of the pyrolysis process for recycling SMC is discussed. The characteristics, compositions and possible ways of reusing the liquid and gaseous fractions are presented. The solid pyrolysis residue has been recycled in another thermoset composite (Bulk Moulding Compound, BMC) and its mechanical properties have been compared with those of virgin BMC. The main conclusion is that pyrolysis can be an appropriate method for recycling thermoset polymeric composites such as SMC. The pyrolysis gas fraction can be sufficient to provide the energy requirements of the process plant. The pyrolysis liquids have high gross calorific values (36·8 MJ kg−1) and are non-polluting liquid fuels; about 40 weight% of such liquids could be used as petrols, and the remaining 60% could be mixed with fuel oils. The solid pyrolysis residue can be recycled in BMC with no detrimental effect on the BMC mechanical properties. Concerning temperature, it has been concluded that 400–500°C are the most suitable temperatures for recycling SMC by pyrolysis.

Relationship between liquefaction yields and characteristics of different rank coals

Abstract Three Spanish low rank coals, including a brown lignite, a black lignite and a subbituminous coal, and a German bituminous coal were liquefied for 1 h in a stirred autoclave with tetralin. The influence of temperature on conversion was studied from 300 to 475°C observing retrogressive reactions at T > 450°C. A study of the influence of rank on liquefaction has been made, finding an increase in conversion as rank decreases. A comparison of these results with those of others investigators is presented. Linear correlations between liquefaction yields and H/C ratios and volatile matter are established.

Effect of fluorine on hydrodenitrogenation activity of doubly promoted (Zn + Co) molybdena-alumina catalysts

Abstract Activity for the hydrodenitrogenation (HDN) of quinoline has been studied at an overall pressure of 7 MPa in the temperature range 623–698 K, on a series of doubly promoted ZnCoMo catalysts supported on fluorinated alumina (0.0–2.0 wt% F). For the F free catalysts the partial substitution of Co by Zn does not affect HDN activity. However, for the fluorinated catalyst series, the HDN activity was found to increase slightly for fluorine contents around 1.0–1.3 wt% F. Simultaneously, a minimum in hydrogenation activity to N free products was observed. These results have been explained in terms of two antagonistic effects. While fluorine favours multilayered MoO 3 crystallites, with shorter dimensions in the lateral direction caused by disruption in the geometry, cobalt has a propensity to intercalate at the edges of the crystals, thus inhibiting the formation of stacks in which the reduced sites, believed to be needed for HDN and hydrogenation, are located.

Influence of the type of solvent on coal liquefaction with different catalysts

Abstract The liquefaction behaviour of a series of solvents in coal liquefaction both without catalyst and with two catalysts, red mud (an Fe 2 O 3 catalyst) and CZMFA2 (a CoZnMo/Al 2 O 3 ) catalyst), was evaluated. Three H-donor solvents (tetralin, 9,10-DHA and 1,2,3,4-THQ), three non-donor solvents (naphthalene, anthracene and phenantrene) and two industrial type solvents (anthracene oil and creosote oil) were tested. The experiments were conducted in a 250 ml autoclave, with 10 g of a subbituminous A coal, 30 g of solvent, 425 °C, 17 MPa operating pressure, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of a solvent is greatly influenced by the type of catalyst used and viceversa, the catalyst effect depends on the solvent utilized. Industrial type solvents can give better coal conversions than strong H-donor solvents if appropriate catalysts are used

Chemical and petrographic characterization and liquefaction yields of Spanish coals

Abstract A preliminary screening of spanish coals including samples of Anthracite from 19 mines, of Bituminous and Subbituminous coal from 32 mines and Hard and Soft brown coal (Lignites) from 32 mines was made based on their proximate and ultimate analysis, looking for the most promising ones as raw materials for liquefaction processes. Relationships between different coal characteristics were established. Ergun correlation between gross calorific value and moisture content seems not to be acceptable for spanish coals. Some of the coals selected (Lignites) were studied via petrographic characterization, and finally tested in a laboratory autoclave reactor of 400 c.c. under standarized operating conditions. Correlations between coal characteristics and the liquefaction yields obtained are compared with other data from the Technical Literature. The results obtained for subbituminous coals about the influence of rank in liquefaction has been verified for our lignites.

Fine and Ultrafine Emission Dynamics from a Ferrous Foundry Cupola Furnace

Abstract Aerosol size distributions from ferrous foundry cupola furnaces vary depending on semicontinuous process dynamics, time along the tap-to-tap cycle, dilution ratio, and the physical and chemical nature of the charge and fuel. All of these factors result in a highly time-dependent emission of particulate matter (PM) 2.5 µm or less in aerodynamic diameter (PM2.5)—even on a mass concentration basis. Control measures are frequently taken on the basis of low-reliability parameters such as emission factors and loosely established mass ratios of PM2.5 to PM 10 µm or less in aerodynamic diameter (PM10). The new environmental requirements could entail unexpected and undesired drawbacks and uncertainties in the meaning and effectiveness of process improvement measures. The development of process-integrated and flue-gas cleaning measures for reduction of particle emissions requires a better knowledge of generation mechanisms during melting. Available aerosol analyzers expand the range of control issues to be tackled and contribute to greatly reduce the uncertainty of engineering decisions on trace pollutant control. This approach combines real-time size distribution monitoring and cascade impactors as preseparators for chemical or morphological analysis. The results allow for establishing a design rationale and performance requirement for control devices. A number size distribution below 10 µm in aerodynamic equivalent diameter was chosen as the main indicator of charge influence and filter performance. Size distribution is trimodal, with a coarse mode more than 12 µm that contributes up to 30% of the total mass. A temporal series for these data leads to identification of the most relevant size ranges for a specific furnace (e.g., the most penetrating size range). In this cupola, this size range is between 0.32 and 0.77 µm of aerodynamic equivalent diameter and defines the pollution control strategy for metals concentrating within this size range. Scrap quality effect is best monitored at less than 0.2 µm in aerodynamic equivalent diameter and has been confirmed as strongly dependent on the physical state of the charge.

COAL LIQUEFACTION WITH ANTHRACENE OIL. INFLUENCE OF SOLVENT PRETREATMENT, TEMPERATURE, CATALYST AND PRESSURE

ABSTRACT The effect of solvent pretreatment, temperature, a CoMo/Al2O3 catalyst and pressure on coal liquefaction with anthracene oil has been evaluated. The experiments were conducted in a 500 ml autoclave with 10 g of a Spanish subbituminous A coal. 30 g of solvent, 1 hour reaction time and 400 rpm stirring speed. The liquefaction products were fractionated into oils, asphaltenes and preasphaltenes using pentane, toluene and THF as extractive solvents. The behaviour of anthracene oil as coal liquefaction solvent is very much enhanced by prehydrogenating it and by the addition ot an active catalyst. The influence of temperature depends on the operating conditions such as solvent pretreatment, catalyst, pressure etc. The addition of an active catalyst greatly improves conversion and the quality of the liquefaction products and diminishes repotimerization reactions. Hydrogen pressure is essential for coal liquefaction with anthracene oil, although over 16 MPa no further increase in coal conversion is observed.

DIRECT HYDROGENATION OF A SPANISH LOW RANK COAL. THE EFFECT OF PROCESS VARIABLES

ABSTRACT The effect of operating conditions on the liquefaction behaviour of a Spanish lignite was studied using a 250 ml stirred autoclave, and the following operating conditions (except otherwise specified): 400 °C, 1 hour, 3.5 MPa initial (cold) H2 pressure, 400 rpm and 40 g/10 g tetralin/coal charge. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue using pentane, toluene and THF as extractive solvents The influence of temperature was explored in the 300–475 °C range, observing little further improvement in liquefaction yields over 400 °C, and retrogressive reactions over 450 °C. The effect of time was studied from 0 to 180 minutes and was concluded that 1 hour is an appropriate period for liquefying a black lignite, since there is little further conversion for longer times. The influence of pressure and gas type was studied using 0, 3.5 and 7.0 MPa initial (cold) pressure of H2 and of N2, and the effect of stirring using 0 and 400 rpm. Little influen...

VARIATION OF TEMPERATURE EFFECT WITH HYDROGEN SUPPLY IN NON-CATALYTIC COAL LIQUEFACTION

ABSTRACT A Spanish subbituminous coal was subjected to non-catalytic liquefaction with tetralin in a 250 ml stirred autoclave. The operating conditions used were: one hour reaction time, 17 MPa operating pressure and 400 r.p.m, stirring speed. The liquefaction products were fractionated into oils, asphaltenes, preasphaltenes and solid residue by a solvent extraction technique using pentane, toluene and THF as extractive solvents. It was found that the influence of temperature on coal liquefaction yields and product distributions varies with the amount of donatable hydrogen. Total coal conversion increases with temperature, when very high tetralin/coal ratios are used On the contrary, when 1/1 ratio is used, conversion does not seem to depend on temperature, and appears to be limited by the amount of liquid medium available as physical solvent. At intermediate tetralin/coal ratios,conversion generally increases with both factors: temperature and amount of solvent. However, retrogressive reactions are obser...

Simulation model to optimize distillation processes

A computer simulation model has been developed integrating the fluid-dynamic design with the classical physical-chemical description of distillation. The software package is solid enough to work with highly non ideal compounds. The fluid-dynamic analysis of the liquid and vapor on each tray allows to develop expressions for the holdup of liquid in trays and downcomers. The model used for the steady state simulation of the column applies material balances, energy balances, equilibrium relationships, and pressure drop relationships, having into account tray hydraulics. Such a model, considered as a previous unavoidable step to any dynamic modelling, has been applied successfully to determine the influence of fluid-dynamic parameters in columns working with sieve, valve, and bubble-cap trays.