Jesús Guardiola

Influence of particle size, fluidization velocity and relative humidity on fluidized bed electrostatics

Abstract The influence of particle size, d p fluidization velocity, U r , and relative humidity, RH, on the degree of electrification reached by a fluidized bed of glass beads has been studied. The static electrification of the bed was measured by means of the potential difference observed between an electric probe and the metallic distributor. The effect of relative humidity appears to be complex and is connected with the quality of fluidization - bubbling or slugging - existing in the bed. A characteristic curve for electrification vs. humidity has been proposed that consists of five zones. The results show that when the value of the relative humidity is lower than a critical value (RH c ), the static electrification of the bed cannot be measured accurately because the adhesion of particles to the probe leads to irreproducible voltage values. Also, the degree of electrification increases with particle size and air velocity. The relationship between the average solid circulation velocity and electrification is studied.

Electrostatic behaviour in binary dielectric/conductor fluidized beds

Abstract The degree of electrification in a fluidized bed of glass beads and mixtures of glass/steel particles has been studied. The basic equipment used for me

Electrostatic collection efficiency in binary fluidized beds

Abstract Fluidized beds of binary mixtures have been used to clean air streams containing dust particles in the size range 4.4 to 14 μ. All beds were composed of glass beads and plastic granules mixed at different proportions. The effect on the electrostatic collection efficiency of a number of variables, including type of collecting mixture, bed height, and gas velocity, was examined. To calculate the single collection efficiency from experimental results, an early model proposed by Clift et al. was used. The electrostatic collection efficiency was determined by subtracting the other individual mechanism efficiencies from the single particle collection efficiency.

Physico-chemical characterization of sizings for the manufacture of E and AR glasses

Abstract Granulometric techniques and Fourier transform infrared (FTIR) and differential thermal analyses were used to study the sizings (covering agents) employed in the manufacture of two kinds of fiber glass, dielectric fiber glass, E, and alkali-resistant fiber glass, AR. It was necessary to subject the sizing samples to pretreatment because the aqueous emulsions have a very high water content and the fibres require acetone extraction before they can be analysed by the techniques used here. Differential thermal analysis in nitrogen in the temperature range from −70 to 500°C was used.

Calorimetric analysis of sizings used for E and AR glass fiber manufacture

Abstract Differential thermal analysis techniques were used to characterize and identify the sizings used to manufacture E and AR glass fibers. Although the use of a nitrogen atmosphere makes it possible to perform a temperature scan from −70 to 500 °C, the changes produced at temperatures between −70 and +70 °C were observed and analyzed in this study. The sizings characterizing the E glass fibers were more stable and less sensitive to aging than those characterizing the AR glass as was confirmed by granulometric analyses.

Granulometric studies of sizings in the manufacture of E and AR glass fibers

Abstract Granulometric techniques were used to characterize samples of the sizings (covering agents) employed in the manufacture of E and AR glass fibers, prior to the study of changes occurring in the sample over time. The emulsions were conditioned so as to avoid saturating the detector tube. The results indicate that AR glass fibers are more sensitive to aging than E glass fibers.

Evaluation and granulometric follow-up of different sizings used in AR- and E-fiberglass manufacture

AR- and E-fiberglass manufacture requires the presence of substances which confer a number of important properties on the fiberglass, such as filament cohesion, resilience or greater/lesser rigidity, durability, protection against abrasion, nonconductibility-elimination of static electricity and inertness. All of these are necessary to ensure perfect binding between the glass and the resin. These substances are called sizings and due to their functional importance in fiberglass manufacture, it is imperative to examine their exact physical and chemical characteristics in order to determine their stability (inertness) and decay (aging). This study deals with determination of size and stability of different sizings by means of granulometric techniques, which permit the measurement of particles that range between 0.6 and 20 μm in diameter. The results demonstrate a greater stability of the sizings used in E-fiberglass manufacture.

The influence of stability of raw materials used in sizings for E and AR fiberglass manufacture

Abstract The additives and reinforcers used in manufacturing the sizings for two types of fiberglass, dielectric E glass and alkali resistant AR glass were physically and chemically characterized by differential thermal analysis (differential scanning calorimetry), Fourier transformed infrared spectrophotometry (FTIR) and granulometry. These techniques can identify irregularities such as contamination, aging, loss of volatile essences, which might affect the fiberglass and its later use. Other analytic methods are also discussed so as to fully demonstrate the stability of the raw sizing material; these include the analysis of viscosity and rheology.

Gas filtration in binary fluidized beds

A systematic experimental study of aerosol filtration in a binary fluidized bed of dielectric material is carried out. Measurements of the collection efficiency when such parameters as gas velocity, bed height, collecting mixture, and column diameter are varied over a wide range have been made. Experimental evidence is given to show that charges generated naturally by triboelectrification of the bed dielectric particles can considerably increase the efficiency of such beds. Furthermore, it is demonstrated that a proper choice of the fluidized mixture can significantly improve the performance of such filters.