Abstract: Offshore oil-spill has become the most emerging problem in the world. In the current paper, a graphene/ZnO/polymer nanocomposite thin film is coated on stainless steel mesh via layer by layer deposition method. The structural characterization of materials is determined by Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The total petroleum hydrocarbons (TPHs) and separation efficiency have been measured via gas chromatography – flame ionization detector (GC-FID). TPHs are reduced to 2 ppm and separation efficiency of the nanocomposite coated mesh is reached ≥ 99% for the final sample. The nanocomposite coated mesh acts as a promising candidate for the separation of oil- water mixture.
Abstract: Petroleum refining is a chemical process in which the raw material (crude oil) is converted to finished commercial products for end users. The fluid catalytic cracking (FCC) unit is a key asset in refineries, requiring optimised processes in the context of engineering design. Following the first stage of separation of crude oil in a distillation tower, an additional 40 per cent quantity is attainable in the gasoline pool with further conversion of the downgraded product of crude oil (residue from the distillation tower) using a catalyst in the FCC process. Effective removal of sulphur oxides, nitrogen oxides, carbon and heavy metals from FCC gasoline requires greater separation efficiency and involves an enormous environmental significance. The FCC unit is primarily a reactor and regeneration system which employs cyclone systems for separation. Catalyst losses in FCC cyclones lead to high particulate matter emission on the regenerator side and fines carryover into the product on the reactor side. This paper aims at demonstrating the importance of FCC unit design criteria in terms of technical performance and compliance with environmental legislation. A systematic review of state-of-the-art FCC technology was carried out, identifying its key technical challenges and sources of emissions. Case studies of petroleum refineries in Nigeria were assessed against selected global case studies. The review highlights the need for further modelling investigations to help improve FCC design to more effectively meet product specification requirements while complying with stricter environmental legislation.
Abstract: In this study a system of machine vision and singulation was developed to separate paddy from rice and determine paddy husking and rice breakage percentages. The machine vision system consists of three main components including an imaging chamber, a digital camera, a computer equipped with image processing software. The singulation device consists of a kernel holding surface, a motor with vacuum fan, and a dimmer. For separation of paddy from rice (in the image), it was necessary to set a threshold. Therefore, some images of paddy and rice were sampled and the RGB values of the images were extracted using MATLAB software. Then mean and standard deviation of the data were determined. An Image processing algorithm was developed using MATLAB to determine paddy/rice separation and rice breakage and paddy husking percentages, using blue to red ratio. Tests showed that, a threshold of 0.75 is suitable for separating paddy from rice kernels. Results from the evaluation of the image processing algorithm showed that the accuracies obtained with the algorithm were 98.36% and 91.81% for paddy husking and rice breakage percentage, respectively. Analysis also showed that a suction of 45 mmHg to 50 mmHg yielding 81.3% separation efficiency is appropriate for operation of the kernel singulation system.
Abstract: A waste-to-energy plasma system was designed by Necsa for commercial use to create electricity from unsorted municipal waste. Fly ash particles must be removed from the syngas stream at operating temperatures of 1000 °C and recycled back into the reactor for complete combustion. A 2D2D high efficiency cyclone separator was chosen for this purpose. During this study, two cyclone design methods were explored: The Classic Empirical Method (smaller cyclone) and the Flow Characteristics Method (larger cyclone). These designs were optimized with regard to efficiency, so as to remove at minimum 90% of the fly ash particles of average size 10 μm by 50 μm. Wood was used as feed source at a concentration of 20 g/m3 syngas. The two designs were then compared at room temperature, using Perspex test units and three feed gases of different densities, namely nitrogen, helium and air. System conditions were imitated by adapting the gas feed velocity and particle load for each gas respectively. Helium, the least dense of the three gases, would simulate higher temperatures, whereas air, the densest gas, simulates a lower temperature. The average cyclone efficiencies ranged between 94.96% and 98.37%, reaching up to 99.89% in individual runs. The lowest efficiency attained was 94.00%. Furthermore, the design of the smaller cyclone proved to be more robust, while the larger cyclone demonstrated a stronger correlation between its separation efficiency and the feed temperatures. The larger cyclone can be assumed to achieve slightly higher efficiencies at elevated temperatures. However, both design methods led to good designs. At room temperature, the difference in efficiency between the two cyclones was almost negligible. At higher temperatures, however, these general tendencies are expected to be amplified so that the difference between the two design methods will become more obvious. Though the design specifications were met for both designs, the smaller cyclone is recommended as default particle separator for the plasma system due to its robust nature.
Abstract: This paper presents a Euler-Lagrange model of the water-particles multiphase flows in a Vorsyl separator where particles with different densities are separated. A series of particles with their densities ranging from 760 kg/m3 to 1380 kg/m3 were fed into the Vorsyl separator with water by means of tangential inlet. The simulation showed that the feed materials acquired centrifugal force which allows most portion of the particles with a density less than water to move to the center of the separator, enter the vortex finder and leave the separator through the bottom outlet. While the particles heavier than water move to the wall, reach the throat area and leave the separator through the side outlet. The particles were thus separated and particles collected at the bottom outlet are pure and clean. The influence of particle density on separation efficiency was investigated which demonstrated a positive correlation of the separation efficiency with increasing density difference between medium liquid and the particle. In addition, the influence of the split ratio on the performance was studied which showed that the separation efficiency of the Vorsyl separator can be improved by the increase of split ratio. The simulation also suggested that the Vorsyl separator may not function when the feeding velocity is smaller than a certain critical feeding in velocity. In addition, an increasing feeding velocity gives rise to increased pressure drop, however does not necessarily increase the separation efficiency.
Abstract: Textile industries cater to varied customer preferences and contribute substantially to the economy. However, these textile industries also produce a considerable amount of effluents. Prominent among these are the azo dyes which impart considerable color and toxicity even at low concentrations. Azo dyes are also used as coloring agents in food and pharmaceutical industry. Despite their applications, azo dyes are also notorious pollutants and carcinogens. Popular techniques like photo-degradation, biodegradation and the use of oxidizing agents are not applicable for all kinds of dyes, as most of them are stable to these techniques. Chemical coagulation produces a large amount of toxic sludge which is undesirable and is also ineffective towards a number of dyes. Most of the azo dyes are stable to UV-visible light irradiation and may even resist aerobic degradation. Adsorption has been the most preferred technique owing to its less cost, high capacity and process efficiency and the possibility of regenerating and recycling the adsorbent. Adsorption is also most preferred because it may produce high quality of the treated effluent and it is able to remove different kinds of dyes. However, the adsorption process is influenced by many variables whose inter-dependence makes it difficult to identify optimum conditions. The variables include stirring speed, temperature, initial concentration and adsorbent dosage. Further, the internal diffusional resistance inside the adsorbent particle leads to slow uptake of the solute within the adsorbent. Hence, it is necessary to identify optimum conditions that lead to high capacity and uptake rate of these pollutants. In this work, commercially available activated carbon was chosen as the adsorbent owing to its high surface area. A typical azo dye found in textile effluent waters, viz. the monoazo Acid Orange 10 dye (CAS: 1936-15-8) has been chosen as the representative pollutant. Adsorption studies were mainly focused at obtaining equilibrium and kinetic data for the batch adsorption process at different process conditions. Studies were conducted at different stirring speed, temperature, adsorbent dosage and initial dye concentration settings. The Full Factorial Design was the chosen statistical design framework for carrying out the experiments and identifying the important factors and their interactions. The optimum conditions identified from the experimental model were validated with actual experiments at the recommended settings. The equilibrium and kinetic data obtained were fitted to different models and the model parameters were estimated. This gives more details about the nature of adsorption taking place. Critical data required to design batch adsorption systems for removal of Acid Orange 10 dye and identification of factors that critically influence the separation efficiency are the key outcomes from this research.
Abstract: This study evaluated to facilitate separation of ABS
plastics from other waste plastics by froth flotation after surface
hydrophilization of ABS with heat treatment. The mild heat treatment
at 100oC for 60s could selectively increase the hydrophilicity of the
ABS plastics surface (i.e., ABS contact angle decreased from 79o to
65.8o) among other plastics mixture. The SEM and XPS results of
plastic samples sufficiently supported the increase in hydrophilic
functional groups and decrease contact angle on ABS surface, after
heat treatment. As a result of the froth flotation (at mixing speed 150
rpm and airflow rate 0.3 L/min) after heat treatment, about 85% of
ABS was selectively separated from other heavy plastics with 100%
of purity. The effect of optimum treatment condition and detailed
mechanism onto separation efficiency in the froth floatation was also
investigated. This research is successful in giving a simple, effective,
and inexpensive method for ABS separation from waste plastics.
Abstract: The separation efficiency of a hydrocyclone has
extensively been considered on the rigid particle assumption. A
collection of experimental studies have demonstrated their
discrepancies from the modeling and simulation results. These
discrepancies caused by the actual particle elasticity have generally
led to a larger amount of energy consumption in the separation
process. In this paper, the influence of particle elasticity on the
separation efficiency of a hydrocyclone system was investigated
through the Finite Element (FE) simulations using crude oil droplets
as the elastic particles. A Reitema-s design hydrocyclone with a
diameter of 8 mm was employed to investigate the separation
mechanism of the crude oil droplets from water. The cut-size
diameter eter of the crude oil was 10 - Ðçm in order to fit with the
operating range of the adopted hydrocylone model. Typical
parameters influencing the performance of hydrocyclone were varied
with the feed pressure in the range of 0.3 - 0.6 MPa and feed
concentration between 0.05 – 0.1 w%. In the simulation, the Finite
Element scheme was applied to investigate the particle-flow
interaction occurred in the crude oil system during the process. The
interaction of a single oil droplet at the size of 10 - Ðçm to the flow
field was observed. The feed concentration fell in the dilute flow
regime so the particle-particle interaction was ignored in the study.
The results exhibited the higher power requirement for the separation
of the elastic particulate system when compared with the rigid
particulate system.
Abstract: Numerical analysis of flow characteristics and
separation efficiency in a high-efficiency cyclone has been performed.
Several models based on the experimental observation for a design
purpose were proposed. However, the model is only estimated the
cyclone's performance under the limited environments; it is difficult to
obtain a general model for all types of cyclones. The purpose of this
study is to find out the flow characteristics and separation efficiency
numerically. The Reynolds stress model (RSM) was employed instead
of a standard k-ε or a k-ω model which was suitable for isotropic
turbulence and it could predict the pressure drop and the Rankine
vortex very well. For small particles, there were three significant
components (entrance of vortex finder, cone, and dust collector) for
the particle separation. In the present work, the particle re-entraining
phenomenon from the dust collector to the cyclone body was observed
after considerable time. This re-entrainment degraded the separation
efficiency and was one of the significant factors for the separation
efficiency of the cyclone.
Abstract: In hydrocyclones, the particle separation efficiency is
limited by the suspended fine particles, which are discharged with the
coarse product in the underflow. It is well known that injecting water
in the conical part of the cyclone reduces the fine particle fraction in
the underflow. This paper presents a mathematical model that
simulates the water injection in the conical component. The model
accounts for the fluid flow and the particle motion. Particle
interaction, due to hindered settling caused by increased density and
viscosity of the suspension, and fine particle entrainment by settling
coarse particles are included in the model. Water injection in the
conical part of the hydrocyclone is performed to reduce fine particle
discharge in the underflow. The model demonstrates the impact of
the injection rate, injection velocity, and injection location on the
shape of the partition curve. The simulations are compared with
experimental data of a 50-mm cyclone.
Abstract: This paper presents the results of an experimental study on the performance of a triboelectric separator of plastic mixtures used for recycling. The separator consists of four cylindrical electrodes. The principle behind the separation technique is based on the difference in the Coulomb force acting on the plastic particles after triboelectric charging. The separation of mixtures of acrylonitrile butadiene styrene (ABS) and polystyrene (PS) using this method was studied. The effects of the triboelectric charging time and applied voltage on the separation efficiency were investigated. The experimental results confirm that it is possible to obtain a high purity and recovery rate for the initial compositions considered in this study.
Abstract: In this research the separation efficiency of deoiling hydrocyclone is evaluated using three-dimensional simulation of multiphase flow based on Eulerian-Eulerian finite volume method. The mixture approach of Reynolds Stress Model is also employed to capture the features of turbulent multiphase swirling flow. The obtained separation efficiency of Colman's design is compared with available experimental data and showed that the separation curve of deoiling hydrocyclones can be predicted using numerical simulation.