Separations In Microchannels Research Articles

Removal of microparticles from hydrogenated oil by a microchannel separation coupling hydrocyclone: Industrial application

Separation techniques utilized in industrial manufacturing account for approximately 10–15% of the total global energy consumption. Energy-efficient separation has been made possible through the use of deep filtration technology. Herein, a novel continuous and regenerative microchannel separator coupled with a hydrocyclone was proposed. The microchannel separator, which had a processing capacity of 30 t/h, was constructed in a petroleum resin plant. This device could separate trace microfine particles in hydrogenated oil. After treatment with the microchannel separator, the average particle removal efficiency was 50.7%, and the turbidity of the hydrogenated oil was reduced by a maximum value of 60.9%. The removal efficiencies of pollutant particles with diameters smaller than 5 μm, in the range of 5–10 μm, and larger than 10 μm in the hydrogenated oil were 44.0%, 54.9%, and 75.9%, respectively. The processing load on the downstream diatomite filter was effectively reduced by the microchannel separator. The lifespan of the diatomite filter increased by 2.3 times compared to its initial value. Hazardous waste emissions decreased from 104 tons/year to 58.5 tons/year. The microchannel separator could be used not only for separating trace fine particles from liquids but also for separating oil and water by modulating the hydrophilic and hydrophobic properties of the particle surfaces.

On-site source-separation of microparticles and reuse of coal gasification wastewater via a micro-channel separator: Performance and separation mechanism

The presence of microparticles in coal gasification wastewater (CGW) tends to cause fouling and blockage of heat exchangers and pipelines, increasing maintenance costs and affecting the stable operation of zero liquid discharge. Here, a 1 m3/h pilot-scale micro-channel separation technology was established for removing microparticles. The feasibility of this technology was verified by conducting a month-long field test. The results showed that the removal rate of suspended solids (SS) and the turbidity of the CGW were 85.2 % and 83.6 %, respectively. Over the operational period, the process was found to run stably, with an effluent turbidity < 20 NTU, which meets the requirements of subsequent working conditions. Scanning electron microscopy and X-ray diffraction techniques were used to characterize the separation medium, and no scaling was found on the surface during operation. In the micro-channel separation process, the removal of fine particles can be achieved without the addition of chemicals, thereby improving the operational stability of the existing process plant. The new method represents an environmentally friendly and sustainable process for the effective removal of SS from CGW.

Characterization of particles inertial focusing and separation in microchannel with triangular cross-section

Characterization of particles inertial focusing and separation in microchannel with triangular cross-section

Purification of hydrogenated oil by microchannel separation coupling hydrocyclone

Hydrogenated oils are commonly used as solvents in the petroleum resin industry. The separation of particulate matter from hydrotreating oil is critical to product quality and the service life of the catalyst in the downstream fixed bed. Conventional separation methods, represented by diatomaceous earth filtration, suffer from low separation efficiency, high material consumption, generation of large amounts of hazardous waste, and cumbersome operation. Therefore, a physical method of microchannel separation coupling hydrocyclone was proposed. A 1 m3/h pilot pretreatment device was established to comprehensively evaluate the particle removal in hydrogenated oil. The high separation efficiency and long operation cycle were achieved by a microchannel separator with 0.5–1 mm particle size quartz sand. The single cycle of the microchannel separator was 75 h. The turbidity was decreased by about 64.3%, which was better than that of the traditional separation method (49.9%). The particle removal in hydrogenated oil by microchannel separator was about 75.0%, while the removal of diatomite separator in the same period was only 44.7%. In a 40 m3/h petroleum resin plant based on a microchannel separator, the operating cost and the hazardous waste emissions are reduced by 1,815,000 CNY/year and 208 tons/year, respectively. It is hoped that this study can not only promote the energy-saving and cleaner production of hydrogenated oil but also provide useful guidance for other petrochemical industries.

Microchannel structure affects fine particulate pollutant interception characteristics

Deep filtration is an important technology for the separation of fine particle pollutants in industrial wastewater. The theoretical core of microchannel separation is the interaction between channel interface and pollutants. Here, microchannels with different shapes and sizes were designed by microfluidic technology and the particle migration process in microchannels was visualized by high-speed camera. This paper studied the effects of apparent depth, inlet structure and channel angle of the interception channel on fluid flow and particle interception. When apparent depth of the interception channel was equidistantly distributed, the flow rate in each channel was uniform, but interception efficiency gradually decreased with the increase of apparent depth. Interception efficiency of the first layer was 16.7 %, while for the 14th layer was only 0.4 %. Interception performance of the upper wall of the inlet of the interception channel was substantially higher than that of the lower wall. The smoother the angle between the interception channel and the mainstream channel was, the better the interception performance. When the angle between the upper and lower walls of the inlet and the mainstream channel was 30° and 60°, respectively, interception efficiency was the optimal, and cumulative interception efficiency of the three filtrations was 92.4 %. Additionally, flow rate and interception efficiency of the interception channel increased with decreasing channel angle. The total interception performance of the 30°–45° group was the optimal, and the total split ratio and total interception efficiency were 65.5 % and 85.5 %, respectively. This provides reference for the change of microchannel structure and the mechanism of particle migration and deposition.

Internal reuse of methanol-to-olefin wastewater based on micro-channel separation coupling hydrocyclone regeneration

Methanol-to-olefin (MTO) is a typical new coal chemical industry example. Due to the large volume of generated wastewater, complex composition including catalysts, aromatics and various oxygen-containing compounds, and serious environmental hazard, wastewater recycling is critical for sustainable industrial development and ecological protection. Herein, a swirl regenerating micro-channel separation (SRMS) technology was proposed to integrate deep filtration and hydrocyclone-enhanced regeneration. A small-scale experimental investigation was first conducted to verify the feasibility of the MTO wastewater treatment. A pilot SRMS device with a treatment capacity of 20 m3/h was constructed, and the device's continuous operation effect and stability were comprehensively evaluated. The separation performance of the SRMS device at different solution pH values and the impact of the hydrocyclone-enhanced regeneration of separation media were discussed in detail. At low solution pH values (<7), the SRMS device exhibits an average separation efficiency of 92.0% for fine particulate matter in wastewater, and the median particle size, d50, decreases from 1.55 to 0.6 μm. As the solution pH increases, the repulsive energy barrier for the medium-contaminant and contaminant-contaminant increases, inhibiting the deposition behavior of particulate pollutants. In addition, hydrocyclone desorbs contaminants deposited on the separation media and the average contaminant residual rate decreases from 3.3 to 0.2 wt%. We propose an industrial application for treating and reusing MTO wastewater (200 m3/h) using the SRMS technology based on the experimental results. The costs of the wastewater treatment process are as low as 0.25 CNY/m3, and the wastewater reuse rate is over 97% without chemical consumption. This work can provide an environmentally friendly and economically sustainable approach to the source management of MTO wastewater.

Collaborative removal of fine catalysts particles and insoluble organics from methanol-to-olefins reaction wastewater using horizontal swirl regeneration micro-channel separation (HSRMS)

The methanol-to-olefins (MTO) process is regarded as a crucial approach for ensuring the sustainable growth of China's chemical industry. However, the fine catalyst particles and insoluble organics in the water system poses a serious threat to the stability of the MTO process. A novel horizontal swirl regeneration micro-channel separation (HSRMS) method for purifying the MTO reaction wastewater was developed in this study. On-site experiments were conducted using a device with a capacity of 1 t/h to investigate the separation and regeneration effects under various parameters and to verify the feasibility of this method through a long-term observation. The results showed that this method could effectively remove the fine solids and insoluble organics in the reaction wastewater, and the device operated stably with fluctuations in both the quality and quantity of wastewater for 24 consecutive days. The suspended solids in the effluent was maintained below 5 mg/L, and the average removal efficiency for insoluble organics exceeded 75%. Furthermore, the excellent regeneration performance was achieved, with solid particles and oil in the media reduced to less than 0.2% after regeneration. This method could ensure long-term stable operation of the water system and outperform other commonly used reaction wastewater treatment methods in terms of investment, maintenance cost, freshwater supplementation, and energy consumption.

Design and simulation of a novel integrated microfluidic chip for cell isolation and culture.

The lab on a chip is utilized as a background and a substrate for creating a proper flow for cellular processes in medicine. In this study, the concepts of cell isolation and cell transfer methods have been discussed. After that, the device of separation and transfer systems has been designed, simulated, and verified by placing the frequency of particle separation and droplet formation, which is tried to introduce a new device that can be used in cellular studies. The optimal operation conditions for the problem have also been investigated. High separation efficiency (99%) could be achieved when the velocity of the sample inlet in the microchannel separator is 180μm/s. Also, a microfluidic device for droplet generation has been designed to transfer the isolated cells to the culture medium. For this purpose, the frequency of droplet production must be synchronized with particle ejection frequency and equals 9.09Hz.

Application of optimized microchannel separator to maximize the reuse efficiency of purified water in the petrochemical industry

In the petrochemical industry, water is purified through a steam stripping system. However, the generated water contains approximately 5–10 mg/L of suspended solids (SS), which does not meet the high-pressure air-cooled water standard (SS ≤0.2 mg/L) proposed by the American Petroleum Institute (API). Therefore, additional efforts are needed to reduce the content of SS and facilitate the recycling of water resources, in addition to saving energy and reducing emissions. This study proposed a physical separation method based on microchannel technology, after which a laboratory-scale experimental study was conducted to assess the influence of important parameters such as bed height, filler type, and particle size on the separation performance of the microchannel separator. Next, a 1 m3/h pilot-plant was established to comprehensively evaluate the removal efficiency and operational stability of SS in the purified water. Our study found that in weakly alkaline purified water, when the filler bed height was greater than 1500 mm, and using 0.105–0.125 mm glass beads, the effluent SS could reach 0.2 mg/L and purified water could be stably obtained with a 95% recovery rate. Therefore, it was estimated that a 100 m³ /h industrial-scale installation could save approximately $1100,000 in salt water and effluent treatment alone, in addition to reducing the annual CO2 emissions by approximately 15,000 t. This is a low-cost method that does not require any additional chemicals while delivering high-efficiency separation, which reduces the demand for fresh water by petrochemical companies, increases corporate benefits, and meets the requirements of emission reduction and environmental protection.

Novel Approaches Concerning the Numerical Modeling of Particle and Cell Separation in Microchannels: A Review

The demand for precise separation of particles, cells, and other biological matter has significantly increased in recent years, leading to heightened scientific interest in this topic. More recently, due to advances in computational techniques and hardware, numerical simulations have been used to guide the design of separation devices. In this article, we establish the theoretical basis governing fluid flow and particle separation and then summarize the computational work performed in the field of particle and cell separation in the last five years with an emphasis on magnetic, dielectric, and acoustic methods. Nearly 70 articles are being reviewed and categorized depending on the type of material separated, fluid medium, software used, and experimental validation, with a brief description of some of the most notable results. Finally, further conclusions, future guidelines, and suggestions for potential improvement are highlighted.

Study on an improved rotating microchannel separator in the intensification for demulsification and separation process

An improved rotating microchannel (IRM) separator was further explored in the intensification for demulsification and separation process. Oil-in-water (O/W) emulsion system of 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507)–water without emulsifier was employed toevaluate the performance of the new equipment. In this experiment, the influence on demulsification separation process was explored by changing the geometrical structure and channel height of the microchannel and combining the liquid–liquid two-phase flow pattern, and the correlation general graph between demulsification efficiency and dimensionless parameters was established. The total demulsification effect of the IRM and the separation capacity of the clear organic phase recovered from demulsification are significantly improved. In addition, the liquid–liquid two-phase flow pattern of the clear organic phase after demulsification and the remaining emulsion in the IRM are observed and recorded by high-speed photography. The separation ability of organic phase from the upper outlet can be significantly improved when the total demulsification rate of IRM is up to 90%. There are 3 types and 6 kinds of flow patterns observed. The results demonstrated that the suitable demulsification performance is obtained when the liquid–liquid two-phase inside the IRM is in a parallel pattern. Finally, the relation map between total demulsification efficiency and the universal flow is drawn, which provides a basis for the accurate control of the IRM device.

Cooperative physical separation of oil and suspended solids from methanol-to-olefin wastewater: A pilot study

Methanol-to-olefin (MTO) is an important non-petroleum chemical process for the preparation of light olefins. However, the MTO process consumes copious amounts of water and produces large amounts of untreated effluent. Therefore, the realization of efficient wastewater treatment and recycling is key to the green low-carbon development of MTO. Here, a cooperative process combining swirl regenerating micro-channel separation (SRMS) and combined fibrous coalescence (CFC) technologies was proposed to separate high contents of oil and suspended matter in MTO wastewater. Using a pilot device with a treatment capacity of 1 m3/h, the average oil content in MTO wastewater decreased from 750 mg/L to <30 mg/L, while the average content of suspended matter decreased from 108 mg/L to <15 mg/L. Compared with a commercial MTO wastewater treatment process (olefin production capacity of 0.6 million tons per annum), the proposed method could reduce wastewater discharges and costs by 57% and US$ 0.23 million per annum respectively. Equipment costs and operational energy consumption were also reduced by 30% and >95% respectively. The combined process may provide the basis for the green and sustainable treatment of MTO wastewater and its recycling.

Industrial application of swirl regenerating micro-channel separation (SRMS) for fine catalysts removal from methanol-to-olefin quench water

Methanol to olefin (MTO) process is a chemical technology for producing low-carbon olefins from coal-based or natural gas-based methanol, which has changed the pattern of low-carbon olefins relying on petroleum cracking. However, a large amount of fine catalyst powders circulating in the water system of the MTO plant threats the sustainability of the process severely. Previously, a pilot-scale study about swirl regenerating micro-channel separation (SRMS) technology to remove the fine waste catalyst powders from MTO quench water was reported. In this study, the SRMS equipment was scaled up to an industrial level with a processing capacity of 400 m3/h based on the results of pilot-scale experiments, and the performance of the industrial unit was monitored for over 6 months. The results obtained directly from the industrial site showed that the SRMS unit based on deep-bed filtration and swirling flow enhanced washing and desorption could effectively remove the fine catalyst particles in the quench water, and the effluent particle concentration was maintained below 20 mg/L. Furthermore, the total oil content in the quench water reduced from 43.2 mg/L to 22.8 mg/L after being processed by the SRMS unit, which demonstrates that the SRMS unit also has an appreciable ability for oil pollutants removal. After the long-term operation of the SRMS unit, the equilibrium concentration of particulate matter in the quench water was reduced to under 50 mg/L, which significantly improved the performance of the quench water heat exchanger and effectively reduced the cleaning frequency of the heat exchanger, air cooler, and other equipment in the water system. Through the industrial-scale technical comparison, this technology outperforms the other common quench water treatment methods in equipment investment, maintaining cost, freshwater supplement, and energy consumption.

Numerical study of particle separation with standing surface acoustic waves (SSAW)

The particle manipulation technology based on standing surface acoustic waves (SSAW) has been widely used with high efficiency and low consumption. However, it is difficult to study particle motion at the microscopic scale with experimental methods and conventional continuous methods. In this paper, computational fluid dynamics (CFD) and the discrete element method (DEM) are used to describe the fluid-particle flow, and the effect of the acoustic field is calculated according to Gorkov's theory. The established model is validated by the particle separation in micro-channel under SSAWs as the simulation results are in good agreement with experiments in publication. The consistency between the numerical simulation results and the experimental results in separation time and separation distance confirms the merits of model. The particle motion, space distribution, velocity field, force analysis and particle collision have been conducted thoroughly to reveal the mechanism of the separation.

Separation of fine waste catalyst particles from methanol-to-olefin quench water via swirl regenerating micro-channel separation (SRMS): A pilot-scale study

From the perspective of resource reserves, the development of coal-based methanol-to-olefins (MTO) technology is regarded as an important direction for the sustainable development of the chemical processing industry in China. However, the wastewater generated in the process of industrial operation has a significant impact on the stability of the process. To remove the fine waste catalyst particles from MTO quench water, a swirl regenerating micro-channel separation (SRMS) technology was developed. A 25 m3/h pilot-scale study was conducted to examine the separation and regeneration effects under different operating parameters and verify the feasibility of this technology through a long-duration experiment. Results showed that for filtration velocities ranging from 11 to 15 m/h, the total separation efficiency was 95–99 %, the removal efficiency of 0.2 μm particles was 83–90 %, and the regeneration cycle was 24–40 h while the waste catalyst particle concentration in quench water was 300–600 mg/L. The optimum regeneration water and gas speeds were determined to be 11–15 m/h and 56.6 m/h, respectively. Moreover, the performance of the pilot plant over 600 h continuous operation effect of was tested, and an average separation efficiency > 95 % with excellent regeneration was obtained.

Hydrodynamic studies on liquid-liquid two phase flow separation in microchannel by computational fluid dynamic modelling

Microfluidic systems undergo rapid expansion of its application in different industries over the few decades as its surface tension-dominated property provides better mixing and improves mass transfer between two immiscible liquids. Synthesis of biodiesel via transesterification of vegetable oil and methanol in microfluidic systems by droplet flow requires separation of the products after the reaction occurred. The separation technique for multiphase fluid flow in the microfluidic system is different from the macro-system, as the gravitational force is overtaken by surface force. To understand these phenomena completely, a study on the hydrodynamic characteristics of two-phase oil-methanol system in microchannel was carried out. A multiphase Volume of Fluid model was developed to predict the fluid flow in the microchannel. An inline separator design was proposed along with its variable to obtain effective separation for the oil-methanol system. The separation performance was evaluated based on the amount of oil recovered and its purity. The capability of the developed model has been validated through a comparison of simulation results with published experiment. It was predicted that the purity of recovered oil was increased by more than 46% when the design with side openings arranged at both sides of the microchannel. The highest percentage recovery of oil from the mixture was simulated at 91.3% by adding the number of side openings to ensure the maximum recovery. The oil that was separated by the inline separator was predicted to be at 100% purity, which indicates that no methanol contamination throughout the separation process. The purity of the separated product can be increased by manipulating the pressure drop across the side openings. Hence, it can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal. Finally, the simulation results showed that the present volume of fluid model had a good agreement with the published experiment.

Rarefied flow separation in microchannel with bends

Abstract

Fishing antitumor ingredients by G-quadruplex affinity from herbal extract on a three-phase-laminar-flow microfluidic chip

A new method for fishing antitumor ingredients by G-quadruplex recognition from Macleaya cordata seeds extracts was established using a three-phase-laminar-flow-chip (TPL chip). The TPL chip integrated the separation of drugs from the complex ingredients and organic solvent extraction, simplifying pretreatment processes and reducing reagents and time. In addition, the chip method showed a lower false negative result, owing to the gentle membrane-free filtration process based on diffusion separation in microchannel. Four ligands with high content in alkaloids of Macleaya cordata seeds were selected, those are chelerythrine (CHE), sanguinarine (SAN), protopine (PRO), and allocryptopine (ALL), which demonstrated affinity with G-quadruplex and were potential for antitumor.

Improved zonal chondrocyte production protocol integrating size-based inertial spiral microchannel separation and dynamic microcarrier culture for clinical application

The zonal property of articular cartilage endows the tissue with biphasic mechanical properties to withstand shearing force and compressional loading. Current treatments for articular cartilage damage are not able to efficiently restore the zonal organisation and functionality. Size-based sorting of freshly isolated chondrocytes from full thickness (FT) cartilage using a spiral microfluidic device was shown to efficiently separate and enrich zonal chondrocytes. The translational application of this sorting protocol is challenging in the clinical setting due to the limited number of autologous chondrocytes from a patient. It is thus essential to explore the practicability of this sorting protocol on expanded chondrocytes. In this study, we first show that size-sorted zonal chondrocytes expanded on microcarriers in dynamic condition (dMC) were able to support comparable proliferation, while maintaining cell morphology, and the zonal cell size-phenotype relation, in contrast to expansion on a tissue culture plate. We further show that post-expansion size-based sorting can be applied on dMC-expanded FT chondrocytes, generating enriched zonal subpopulations that form phenotypically distinct cartilage constructs in the 3D hydrogel. This study demonstrates a novel scale-up zonal chondrocyte production protocol, incorporating size-based zonal chondrocyte separation and dMC platform, to maintain zonal chondrocytes’ phenotypes better to support zonal repair of articular cartilage.

Strategy toward Miniaturized, Self-out-Readable Resonant Cantilever and Integrated Electrostatic Microchannel Separator for Highly Sensitive Airborne Nanoparticle Detection.

In this paper, a self-out-readable, miniaturized cantilever resonator for highly sensitive airborne nanoparticle (NP) detection is presented. The cantilever, which is operated in the fundamental in-plane resonance mode, is used as a microbalance with femtogram resolution. To maximize sensitivity and read-out signal amplitude of the piezo-resistive Wheatstone half bridge, the geometric parameters of the sensor design are optimized by finite element modelling (FEM). The electrical read-out of the cantilever movement is realized by piezo-resistive struts at the sides of the cantilever resonator that enable real-time tracking using a phase-locked loop (PLL) circuit. Cantilevers with minimum resonator mass of 1.72 ng and resonance frequency of ~440 kHz were fabricated, providing a theoretical sensitivity of 7.8 fg/Hz. In addition, for electrostatic NP collection, the cantilever has a negative-biased electrode located at its free end. Moreover, the counter-electrode surrounding the cantilever and a µ-channel, guiding the particle-laden air flow towards the cantilever, are integrated with the sensor chip. µ-channels and varying sampling voltages will also be used to accomplish particle separation for size-selective NP detection. To sum up, the presented airborne NP sensor is expected to demonstrate significant improvements in the field of handheld, micro-/nanoelectromechanical systems (M/NEMS)-based NP monitoring devices.