A mis padres que con su amor incondicional me apoyaron en todo momento, en mis momentos de fortaleza y de debilidad, siempre estuvieron para incentivarme a seguir adelante. El Autor. Para denominar la Intensidad se utiliza la letra I y su unidad es el Amperio A. Las aleaciones empleadas son las que se dan en la tabla, y se procura la mayor independencia posible de la temperatura, es decir, que se mantenga el valor en ohmios independientemente de la temperatura.
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No se dispone de resultado final Publicaciones No se dispone de publicaciones Exploitable Results Plastics separation by electrostatics Sorting waste plastics into polymer types is labour intensive and ineffective leading to a recycled product which is costly to produce yet a low value to plastics users.
What is needed is effective, automatic separation giving a low cost product which can replace new, pure polymers. Separation processes based on the different electrostatic properties of different plastics have been tried before but successful laboratory processes have often failed in an industrial environment because of the notorious variability of electrostatic properties.
The work carried out for this programme showed that the causes of variation in electrostatic properties, if properly understood and quantified, could be used to advantage.
Conditions could then be selected and controlled to maximise the differences between materials and so enhance separation.
This would lead to improved separation efficiency for materials already recycled, and discrimination between materials which currently cannot be separated.
A general purpose laboratory separation apparatus was designed to exploit a wide range of electrostatic properties and effects, singly or in combination. Trials have been carried out with a washed, post consumer, mixed polyvinyl chloride PVC and polyethylene terephthalate PET flake, knowing that the maximum value of these materials cannot yet be realised because of the less than perfect separation achievable.
Without the careful control essential to the new process, random variation between these extremes of conditions could be expected. The clear conclusion from this work is that automatic electrostatic separation of polymers can be enhanced by control of those conditions which, when uncontrolled, lead to poor and variable discrimination.
Furthermore, laboratory apparatus and procedures are now available for more extensive trials with other mixtures of polymers and polymer grades. Solution of electrostatic problems in powder handling and processing Electrostatic tribocharging of powder causes it to be attracted to, or repelled from, a nearby surface or surrounding particles. This can lead to variations in bulk density, choking of machines and a range of other industrial problems.
Research work carried out for this project aimed to improve the economic efficiency of pneumatic conveying, milling and mixing in the test-case process plant, by reducing electrostatic powder adhesion. The first stage of the project was to find the best powder categorisation methods. In the second stage, laboratory test rigs to model three relevant processing machines were developed; a pneumatic conveyer, a ball-mill and a fluidised bed homogeniser.
The results dealt principally with the observations and predictions made using these rigs. In the third stage, laboratory charge control techniques were repeated using the full-scale industrial machines, giving general agreement with the experimental results. Two important conclusions were that powders cannot readily be classified in terms of laboratory chargeability tests, and that laboratory equipment which models a machine closely may allow predictions of powder behaviour.
Experience gained from this project is being used to improve a range of industrial situations, some not even immediately recognisable as having a static charge cause for the problem, via ongoing consultancy work. Solutions to electrostatic problems in powder handling and processing Electrostatic charges are the cause of problems in many industries where powdered materials are manufactured or processed.
Electrostatic hazards are now well understood, but powder handling and processing problems still occur which can reduce quality and productivity leading to inferior products and higher costs. At the root of these difficulties is a lack of understanding of their cause and a lack of appropriate solutions, shortcoming which are being addressed by a consortium of 5 companies.
By focussing on the specific operations of one of the partners the group has been quantifying electrostatic problems and comparing various charge control techniques. The specific processes which have been addressed, and for which laboratory scale units have been constructed, are pneumatic conveying, milling, and mixing and blending. Clearly, practical problems with these processes can now be readily investigated. Furthermore, the broad appreciation of powder problems and their solutions through working with these processes means many of the lessons can be applied to other processes.
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AUTOINDUCCION E INDUCCION MUTUA