Solid Gas Separation Research Articles

Filtration in Pharmaceutical Industries and Role of Textile

Filtration is considered the keystone for clarification and control of contamination in pharmaceutical and biopharmaceutical manufacturing. From production to in-process to chemical and research laboratories to the purification of water for sterile and nonsterile products, all of which involve some form of filtration in order to achieve a good manufacturing practice (GMP). Textile materials possess a significant contribution to the pharmaceutical filtration system. Textile material in pharmaceutical filtration is used in the form of filter media or medium. Flexible in nature, large pore distribution and non-metallic properties of textile materials have led to widespread use as filter media for many years. In filtration processes, a proper selection of filter media/ membrane material is usually the most critical aspect for ensuring efficient separation. Generally, solid-liquid and solid-gas separation is done by the filter media. This paper emphasises solid-liquid filtration. Moreover, this paper reviews the water requirement, filtration processes and the role of textile in the filtration system of pharmaceutical industries. This paper also offers insight into the current market trend and COVID-19 impact on the pharmaceutical filtration industry. Furthermore, gathered information may be helpful to those studying and working in pharmaceutical engineering, filtration technology, and wastewater treatment and can get knowledge about filtration systems.

Fine particle removal from gas stream using a helical-duct dust concentrator: Numerical study

In this study, separation efficiency and pressure drop of a helical-duct dust concentrator have been investigated numerically and experimentally. The mixture multiphase approach has been applied for CFD11Computational Fluid Dynamics simulations of the process. The effects of various geometrical (helical-duct diameter and number of helix rounds) and operational parameters (inlet air mass flow rate, solid mass fraction and flow split ratio) on the solid-gas separation efficiency and pressure drop have been investigated by CFD simulations. It was found that by increasing the flow split ratio - as the main effective parameter on concentrator separation performance - the concentrator efficiency increased up to 75.8%. Finally, a new dimensionless correlation has been proposed to determine the pressure drop by using Euler and Reynolds dimensionless groups. The proposed correlation showed a fair agreement with the experimental results.

Continuous testing of silica-PEI adsorbents in a lab.-scale twin bubbling fluidized-bed system

In this study, a lab.-scale twin bubbling fluidized-bed system (TBS) has been used continuously to test the performance for CO2 adsorption of silica-PEI (S.PEI) adsorbents, containing 40 wt.% of PEI, which were supplied by the University of Nottingham (UNOTT). The TBS comprises bubbling-bed adsorption and desorption reactors, a riser for pneumatic conveying of solids from the adsorption to the desorption reactor, and a cyclone for solid-gas separation. The adsorbent prepared using PEI with a molecular mass of 800 (S.PEI-0.8K) was a preliminarily tested for almost 24 h at the given operating conditions by varying the inlet sorbent/CO2 mass ratio at the adsorber to analyse the CO2 removal efficiency in the adsorption reactor and the dynamic sorption capacity of the adsorbent. A 180-h continuous test was then carried out by changing various experimental conditions such as the H2O concentration, reaction temperature, solid layer height, reaction gas flow rate, and inlet sorbent/CO2 mass ratio at the adsorber using PEI with a molecular mass of 5000 (S.PEI-5K) adsorbent. In this test, a CO2 removal efficiency of above 80% and a dynamic sorption capacity greater than 6.0 wt.% were achieved.

Enhancement of cyclone solid particle separation performance based on geometrical modification: Numerical analysis

Abstract Computational fluid dynamic (CFD) methods are used to investigate the enhancement of the solid-gas separation efficiency by adding tangential chambers to the conical section of a conventional cyclone separator. It is shown that the addition of the tangential chamber enhances the separation of the particles near the conical section wall, and hence the overall separation efficiency, particularly for small particles (1–3 μm). This enhancement occurs with only an 8% increase in the pressure drop between the inlet and outlet of the cyclone. The effects of the inlet velocity and the number of the tangential chambers on the separation efficiency are studied to find the optimum conditions. It is shown that the increase in the velocity enhances the efficiency at the expense of an increase in the pressure drop (the increase in the inlet velocity from 14 to 20 m/s doubles the pressure drop). The model also shows that the addition of one tangential chamber produces a lower dissipation rate of turbulence in the cyclone as compared to multiple chambers, and hence a higher separation efficiency. The efficiency of the proposed geometrical modification is also compared against the conventional cyclone design and that with another geometrical modification reported in the literature (i.e., a cyclone with an elongated conical length). The results reveal that the proposed modification in this paper enhances the separation efficiency for small particles (less than 3 μm) up to 50% compared to the conventional and the elongated designs and 15% for large particles (larger than 6 μm) compared to the conventional design. The proposed modification was also compared to the conventional design in terms of the erosion rate of the cyclone walls, which is increased by 50%.

Increasing efficiency of natural gas cyclones through addition of tangential chambers

This paper experimentally investigates the effect of adding tangential chambers on the efficiency of solid-gas separation in cyclone separators used in gas treatment. To investigate the effect of such an addition on the cyclone performance, the size distribution of the solid particles escaping with the clean gas is compared between the conventional cyclone design and that with the proposed addition. It is shown that the tangential chamber enhances the separation efficiency by 21% in the conventional cyclones, particularly for 4-μm particles.

Enhancement of solid particle separation efficiency in gas cyclones using electro-hydrodynamic method

This paper investigates the feasibility of using electro-hydrodynamic forces to enhance the efficiency of solid-gas separation in cyclone separators. Electro-hydrodynamic forces are applied using electrostatic coating of particles on which the lateral forces are increased in the presence of a radial static charge. It is shown that these additional forces are larger than the centrifugal force. The experimental and theoretical results show that the proposed method enhances the efficiency by 33% for the particle sizes of 4 μm, and hence can be used as an enhancement to the conventional cyclone designs.

Design of a novel gas cyclone vortex finder using the adjoint method

Gas cyclones have many industrial applications in solid–gas separation. The vortex finder is an essential part in gas cyclones where the shape and diameter highly affect the cyclone performance. Many optimization studies have been conducted to optimize the cylindrical vortex finder diameter. This study introduces a new vortex finder shape optimized for minimum pressure drop using the discrete adjoint method. The new optimum cyclone will save 66% from the driving power needed for the Stairmand cyclone. To efficiently perform the grid independence study for the new cyclone, a new framework using the adjoint solver and the grid convergence index is proposed and tested. The proposed framework relies on local mesh adaptation instead of the global mesh refinement approach. A comparison of numerical simulation of the new cyclone and the Stairmand cyclone confirms the superior performance of the new vortex finder shape for the pressure drop and the cut-off diameter. The results of this study open a new era gas cyclones geometry optimization by using the adjoint method instead of the traditional surrogate based optimization technique. Moreover, the computational costs for the grid independence studies will be reduced via the application of the adjoint methods.

Surface microstructure evolution of polytetrafluoroethylene microporous materials by a casting–lyophilization–calcining (CLC) method

The novel casting–lyophilization–calcining (CLC) process endows PTFE microporous materials with a highly asymmetric structure and excellent filtration precision in solid–gas separation.

Comparative Study of the Efficiency among Conventional Cyclones and Cyclones with Filter

The cyclones are one of the most known apparatus destined to the solid-gas separation. These equipments are used in the chemistry industry; its popularity is due mainly to the simplicity, low energy requirements and ability to operate at high temperatures and pressures. One of the aims of this work was to evaluate the influence of some geometrics variables in the performance of conventional cyclones and filtering cyclones. The chosen variables were: conic part length (Zc), the underflow diameter (Du), the overflow diameter (Do) and the finder length (Sc). The cyclones conventional and with filter were compared and it was observed that the introduction of a filter main in substitution to the metallic conic part of cyclones allows a appreciable reduction in the pressure drop and consequently a smaller consumption of energy. The efficiency in the new cyclone was a little smaller than the conventional equipment.

Theory and application of cyclone with impulse electrostatic excitation for cleaning molecular gas

This paper introduces the structure, characteristics and operating principle of a cyclone impulse electrostatic precipitation (CIESP), and presents the solid–gas separation mechanism of CIESP. The hydromechanics equations of particles in solid–gas separation are set up with the goal of analyzing the characteristics of impulse corona discharge. The application of CIESP for cleaning molecular gas in a catalyst plant is explained. We conclude that CIESP is very suitable for cleaning sticky dust particles from exhaust gases of molecular sieve catalyst plant, and has high overall collection efficiency, while the migration velocity is approximately twice that of the electrostatic precipitation (up to 0.15–0.18 m/s). The theoretical formula for particle migration velocity is experimentally verified.

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.

Study of the cut diameter of solid–gas separation in cyclone with electrostatic excitation

This paper analyzes the solid–gas separation mechanism of cyclones with electrostatic excitation, and proposes nonlinear differential equations, describing the dynamics in cyclone with electrostatic excitation. Using chaos theory, a equation of cut diameter is obtained, and then verified by experiment. It is found that the equation of cut diameter can be used for the design optimal for the electrocyclone separator and improve its performance.

World bank endorses water resources strategy

Gas cyclones have many industrial applications in solid–gas separation. The vortex finder is an essential part in gas cyclones where the shape and diameter highly affect the cyclone performance. Many optimization studies have been conducted to optimize the cylindrical vortex finder diameter. This study introduces a new vortex finder shape optimized for minimum pressure drop using the discrete adjoint method. The new optimum cyclone will save 66% from the driving power needed for the Stairmand cyclone. To efficiently perform the grid independence study for the new cyclone, a new framework using the adjoint solver and the grid convergence index is proposed and tested. The proposed framework relies on local mesh adaptation instead of the global mesh refinement approach. A comparison of numerical simulation of the new cyclone and the Stairmand cyclone confirms the superior performance of the new vortex finder shape for the pressure drop and the cut-off diameter. The results of this study open a new era gas cyclones geometry optimization by using the adjoint method instead of the traditional surrogate based optimization technique. Moreover, the computational costs for the grid independence studies will be reduced via the application of the adjoint methods.

Study of solid–gas separation mechanism of cyclone with impulse excitation

On the basis of experimental study of the performance of cyclone impulse electrostatic precipitation (CIESP), the solid–gas separation mechanism of CIESP is presented. The charge process on particle is described. The paper studies acting force and movement law of the charged particle, and sets up hydromechanics equation of particle in solid–gas separation on the basis of analyzing the characteristics of impulse corona discharge. The migration velocity of the particle is calculated, the new formula of grade efficiency is concluded, and verified by experiment. Applying impulse supply to cyclone electrostatic precipitation (CESP) is an innovation, the new solid–gas separation theory of cyclone with impulse excitation can provide a theoretical basis for developing a new separator and improving the quality of the separator equipment.