Characterization of Bulk Solids for Dense Phase Pneumatic ConveyingSánchez, Luis G. (2002) Characterization of Bulk Solids for Dense Phase Pneumatic Conveying. Master's Thesis, University of Pittsburgh.
AbstractThe uses of pneumatic conveying systems have been widely used in industry for many years, increasing significantly in recent years. Numerous bulk solid materials with dramatically different particle properties are being transported pneumatically. In recent times, there has been a considerable increase in the use of the dense phase mode of flow for pneumatic conveying system of bulk solids. The attraction of this method of conveying is the low energy consumption, low velocity, and minimum degradation of material and reduced erosion of the pipeline. One of the most challenging issues in solids handling is being able to predict ahead of time whether a powder or granular material will convey in a dense phase plug format. Up until the present, we have had to rely on the carrying out of almost full scale testing on the material to ascertain if the material will convey in this mode. In general, measurements are made on the material, usually of the table-top variety and the resulting values are correlated to the actual large scale testing or inf erred from known operating systems. Thus, one sees the terms of bulk density, permeability and deaeration as being the most common properties measured and analyzed. Former researchers have made good progress in the prediction of dense phase capabilities of materials. The methods chosen to predict these capabilities of the materials should not require extraordinary devices and designs, such as conveying tests. In previous studies, little standardization was developed on how the experiments should be conducted. As with many measurements on particulate systems, if standardization is not followed, a variety of different results can be obtained. For the tests of permeability and de-aeration, this study has attempted to describe the process for construction of the experimental unit as well as the procedures for carrying out the tests. This study will provide detailed guidelines on the procedure and process. As time goes on, these methods certainly can be modified and improved upon so that a final consistent analysis can be carried out throughout the world. The potential of classification of bulk solids to determine the feasibility of conveyance has been of interest to many researchers. While each investigator carried out experiments consistently, there are differences in their work. A review of their studies is developed in the present work and provided an important database of materials studied in conveying studies. Our present study employed 175 different materials in an experimental procedure to cover a wide range of bulk so lid properties in an effort to asset the ability of the materials to be conveyed in a pulsed piston format. In the process of exploring different classifications, other modes of transport were also suggested. A number of researchers have been able to carry out experiments both in the classification manner as well as in performance conveying tests to establish the transport conditions. Our study did a limited amount of the conveying tests but explored the characterization element in considerable detail. A number of different dimensionless groups were explored in order to find a correlation that would allow one to take some basic data such as article characteristics, permeability and de-aeration factors in order to establish whether a plug flow would occur. The analyses of those numbers showed that some dimensionless numbers can give an indication of the mode flow of the material to be conveyed. Numerous theoretical and empirical correlations have been developed for prediction of pressure drop in conveying systems. In this work, the dense phase data of various researchers are used to evaluate the models proposed to predict the pressure drop for horizontal and vertical pneumatic dense phase conveying. This study indicated that Konrad and Mi' s models are very good models to predict the pressure drop in most of the data evaluated. To understand the performance of pneumatic conveying and determine some important parameters which are difficult to predict theoretically, experiments and investigations were carried out in an industrial conveying system. Three plastic pellet materials were used in testing the plug flow in a 4-inch aluminum tubing fed by a rotary valve. The evaluation of models for the industrial experimental data performed in MAC equipment confirms the conclusion obtained in the wide range of data studied. The most important models to predict the pressure drop in a conveying system were the Mi and Konrad models, with error of ±25% in the estimation of the pressure drop. Share
Details
MetricsMonthly Views for the past 3 yearsPlum AnalyticsActions (login required)
|
![[feed]](/images/feed-icon-32x32.png){kind=icon}