João Jorge Ribeiro Damasceno

Performance analysis and design of filtering hydrocyclones

The filtering hydrocyclone is a solid-liquid separation device patented by the Chemical Engineering Department at the Federal University of Uberlândia, which consists of a hydrocyclone whose conical section was replaced by a conical filtering wall. The objective of this work is to compare the performances of the filtering hydrocyclones designed by Bradley and by Rietema. The experimental results obtained with the filtering hydrocyclones under the same operational conditions as those used with the conventional device allow the conclusion that performance of the Bradley and Rietema types is significantly influenced by the filtering medium. Rietemas filtering hydrocyclones had a lower volumetric feed flowrate than the conventional device and Bradleys filtering hydrocyclones showed increases in this same variable. In both designs, overall efficiency was influenced by the underflow-to-throughput ratio.

Analysis of the influence of the filtering medium on the behaviour of the filtering hydrocyclone

Abstract The filtering hydrocyclone is a solid–liquid separation device patented by the Chemical Engineering Department of the Federal University of Uberlândia [M.A.S. Barrozo, J.J.R. Damasceno, Brazilian Patent No. 9001889, 1991.], which consists of a Bradleys cyclone whose conical section was replaced by a conical filtering wall. The objective of this work was to investigate the effects provoked by three different filtering media on the performance of that equipment. Within the limits of the region investigated — pressure drops in the range 88260–205940 N m−2 — these filtering hydrocyclones were compared to the conventional Bradleys hydrocyclone and displayed increases in both feed flowrates and reduced cut sizes. A dependence of the underflow-to-throughput ratios on the filtering medium resistance was also registered. Based on the experimental results, an explanatory mechanism for the phenomena observed as well as design equations accounting for the influence of the filtering medium resistance have been proposed, allowing the prediction of the performance of filtering hydrocyclones and providing a new alternative in terms of solid–liquid separation devices.

Differences of Behavior between Filtering Hydrocyclones with Bradley and Rietema Geometries

Hydrocyclones constitute an important class of devices intended for the solid-liquid suspensions separation. Those equipments are divided in several families, which differ to each other in the geometric relationships. The filtering hydrocyclone is a device which consists of a cyclone, whose conical section was replaced by a conical filtering wall. The objective of this work is to compare the performance of the filtering hydrocyclones of the Bradleys and Rietemas designs. The experimental apparatus was composed of a well-stirred tank, a centrifugal pump, an agitator, valves and the filtering hydrocyclones with Bradleys and Rietemas geometries. The experimental results obtained with the filtering hydrocyclones in the same operation conditions that their conventional devices, allow to conclude that the performance of the hydrocyclones of the families Bradley and Rietema is significantly influenced by the presence of the filtering medium. The Rietemas filtering hydrocyclones supplied smaller volumetric feed flowrate in relation to the conventional device, the Bradleys filtering hydrocyclones presented increments for this same variable. In both geometry, the overall efficiencies were influenced by the underflow-to-throughput ratio.

Numerical Methodology for Orifice Meter Calibration

Orifice Meters are mechanical devices used to measure gases and liquids flows. Due to manufacturing, installation and operation simplicity, the orifice meters are widely used in the industrial processes in which there is flow of gases or liquids. Moreover, their acquisition and operation costs are smaller than the ones verified for other flow meters (Venturi, flowmeter). However, before the utilization of any calibration orifice meters, they demand an experimental calibration procedure. Thus, in order to suppress this laborious experimental procedure, this work objectified to apply computational fluid dynamics techniques (CFD) to numerically predict the Calibration Coefficient of the orifice meter. The adopted numerical methodology was able to satisfactorily predict the discharge coefficients, presenting an economic alternative when compared to traditional experimental approaches.

Filtration on Hydrocyclone of Optimized Geometric Relationships

The filtering hydrocyclone is a solid-liquid separation device patented by the Chemical Engineering School of the Federal University of Uberlândia, which consists of a hydrocyclone whose conical section was replaced by a conical filtering wall. During the operation of these separators, besides underflow and overflow streams, the existence of a filtrate stream generated by the filtering process is found in the permeable conical region of the hydrocyclones. Vieira et al. (2006) got a filtering hydrocyclone that simultaneously presented low Euler Number and cut size diameter because its geometric relationships has been optimized. The objective of this work was to analyze the behavior of this optimized filtering hydrocyclone through computational fluid dynamics and experimental studies. In the same operational conditions of the conventional hydrocyclone, the performance of this optimized filtering hydrocyclone was significantly influenced by the filtration. The filtration caused decreases in the Euler number and increment in the total efficiency.

Prediction of Performance of a Hydrocyclone with Filtering Cylinder

Hydrocyclones are centrifugal devices widely used in chemical industries and they are used to the solid or liquid particles separation of a fluid according to the density and size distribution of the dispersed phase. In order to maximize the separation in these devices, this work had as objective to study the influence of the filtration during the process of separation in hydrocyclones. Thus, experimental data were used to predict the behavior of a hydrocyclone having a porous cylinder in the same operating conditions of a conventional hydrocyclone (impermeable cylinder). The experimental studies showed that the filtration interferes directly in the performance of the separator, so the filtering hydrocyclone required a higher pumping power. Moreover, the experimental data also indicated that the presence of the porous cylinder in the hydrocyclone was able to increase the number of dragged particles in the underflow, increasing therefore the efficiency of separation.

Analysis of tecniques for measurement of the size distribution of solid particles

Determination of the size distribution of solid particles is fundamental for analysis of the performance several pieces of equipment used for solid-fluid separation. The main objective of this work is to compare the results obtained with two traditional methods for determination of the size grade distribution of powdery solids: the gamma-ray attenuation technique (GRAT) and the LADEQ test tube technique. The effect of draining the suspension in the two techniques used was also analyzed. The GRAT can supply the particle size distribution of solids through the monitoring of solid concentration in experiments on batch settling of diluted suspensions. The results show that use of the peristaltic pump in the GRAT and the LADEQ methods produced a significant difference between the values obtained for the parameters of the particle size model.

Analysis of the efficiency of a cloth cyclone: the effect of the permeability of the filtering medium

The cloth cyclone is a solid-gas separation device that consists of a Lapple cyclone whose conical section has been replaced by a conical filtering wall. The present research was undertaken with the aim of examining the influence of a conical filtering section made of three different materials on the performance of a Lapple design cyclone. The overall efficiency and pressure drops of the cloth cyclone and a conventional one were compared. The effect of the filtering medium on the behavior of the cyclone was also evaluated using an equation that correlates the cut size diameter with the operational conditions, the properties of the gas-solid system and the resistance of the filtering medium. The experimental results demonstrated that the overall efficiency of the conventional cyclone was similar to that of the proposed device, with the latter displaying a reduction in pressure drop. Consequently, energy costs are lowered when cloth cyclones are used.

Analysis of the Compressibility of Sediments in Batch Settling Tests Using Newtonian and Non-Newtonian Fluids

The study of compressibility in deformable porous media is of interest in many industrial processes, such as, filtration, thickening and during oil well drilling processes in the petrochemical sector. In this work the compressibility of porous media was evaluated by the comparison of solid concentration profiles in sediments using fluids with Newtonian and non-Newtonian behavior. For this, consolidation tests in distillated water, solutions of xanthan and glycerol were performed in a vertical column from the gravitational settling of suspensions. The porosity distribution in the formed sediment was obtained after the complete settling of particulate material. The local porosity measurements were performed using the ionizing radiation emitted by americium-241. The gamma-ray attenuation technique used in this study allowed the realization of nondestructive measurements for achieving local concentration of solids. The results showed that the rheological behavior of the fluid does not change significantly the compressibility of the porous matrix.

Fluid Dynamics Study of the Influence of the Position of the Feed in Fabric Filters

Abstract The fabric filter is a pioneering piece of equipment used to reduce the emission of small size particulate matter from industrial sources. It is relatively inexpensive and offers easy operation and high efficiency of collection for a wide range of sizes. Aiming at making the filtration operation more efficient and economical, this work investigated the best position of the feed in the filtration box and, consequently, the best way to clean the fabric filter. The cleaning system used in fabric filters is of great importance for the efficiency and durability of the equipment, and it defines the position of the dirty gas inlet in the filtration box. This work used CFD (Computational Fluid Dynamics) techniques to simulate the pressure drop and the fluid dynamics of the gas as a function of the position of the feed, which was varied from the top to bottom of the filtration box. The simulations were carried out using a new polyester filter for each feed position. According to the results, the fluid should be fed next to the bottom of the filtration box, which produces a smaller pressure drop, a better distribution of the gas and less wear of the bags adjacent to the gas feed.