Countercurrent Process Research Articles

The Effect of the Countercurrent Washing Process for KP Brown Pulp Stock Line

The Effect of the Countercurrent Washing Process for KP Brown Pulp Stock Line

A novel 3D green element method to simulate counter-current spontaneous imbibition considering the effect of gravity

This paper firstly proposes a novel three-dimensional (3D) Green element method (GEM). We have proven it by theoretical error analysis that, the novel GEM with the third-order accuracy, has good convergence and stability, which are the advantages that previous GEMs do not have. This novel method is used to numerically simulate 3D core's counter-current imbibition process with gravity effect, and 1D, 2D and 3D models are implemented to depict good convergence and accuracy of proposed method. Compared with finite difference method (FDM) used by many previous studies, the novel method has the same advantage as previous GEMs, that it requires less elements to achieve a good agreement between simulation results and experiment data. Moreover, specific gravity effect is analyzed, and three typical stages of gravity effect are divided. In summary, the novel 3D GEM and corresponding 3D simulator are effective to simulate counter-current imbibition of the real 3D core considering the effect of gravity.

Generalizing Countercurrent Processes: Distillation and Beyond

AbstractThe implementation and exploitation of countercurrent movement between different phases is a well‐established principle to enhance the performance of separation processes. The improvements are essentially due to the establishment and application of more favorable driving forces compared to co‐current operation. The success of dedicated multistage countercurrent distillation processes has been a key motivator for the development of many other principles of countercurrent separation processes. This promoting aspect was strongly supported by the availability of graphical solutions of the underlying mass balance equations, e.g. the McCabe‐Thiele diagram. Selected applications of countercurrent separation processes are presented, which demonstrate extensions exploiting spatial and temporal sub‐structures and additional phase changes.

Maximum Production Minimum Pollution (MPMP), Necessary but not Sufficient for Sustainability

Sustainable Development (SD) is essential for modern economy. Sustainable Development Engineering (SDE) is a subsystem of SD and concentrates on the engineering sides of SD. Environmental Engineering (EE) is also essential for clean modern industry. EE is necessary for SD but is not sufficient, in order to make it sufficient the feedstock must be from Renewable Raw Materials (RRMs) sources. SD is formed of the sub-systems SDE, EE and RRMs. In this paper membrane catalytic reactors are used to achieve Maximum Production and Minimum Pollution (MPMP) by removing hydrogen from dehydrogenation side. The efficiency increases when a hydrogenation reaction is taking place in the other side of the membrane. This paper is addressing a practical case for this behavior giving MPMP which is necessary but not sufficient for sustainability. The further step to make it sufficient is the use of feedstock from RRMs which is not addressed in the paper. It is shown that the counter-current process is more efficient than the co-current one. This investigation and conclusions are obtained by reliable mathematical modeling, numerical solution and computer simulation of the model differential equations. More difficult ones for the Countercurrent case.

Quantitative assessment of environmental impact of biologics manufacturing using process mass intensity analysis.

Process mass intensity (PMI) is a benchmarking metric to evaluate the efficiency of a manufacturing process, which is indicative of the environmental impact of the process. Although this metric is commonly applied for small molecule manufacturing processes, it is less commonly applied to biologics. In this study, an Excel based tool developed by the ACS GCI Pharmaceutical Roundtable was used to calculate PMI of different manufacturing processes for a monoclonal antibody (mAb). For the upstream process, three different versions were compared: fed-batch, fed-batch with N-1 perfusion, and perfusion in the N-stage bioreactor. For each upstream process version, an appropriate downstream operational mode was evaluated from the following: a column chromatography process utilizing Protein A and anion exchange (AEX) resin, a Protein A column and an AEX membrane, and a three-column periodic counter-current (3C PCC) chromatography process for Protein A and an AEX membrane. The impact of these different process variations on PMI was evaluated. Of all the process inputs, water contributes about 92-94% of the overall PMI. Additionally, the upstream processes and the chromatography steps account for 32-47 and 34-54% of the overall PMI, respectively. Sensitivity analysis was performed to identify opportunities for further reducing PMI. These data indicate that a semicontinuous manufacturing process (perfusion, 3C PCC, and AEX membrane) is the most efficient process, resulting in a 23% reduction of PMI when compared with the fed batch and two-column chromatography process. Together, PMI can be used to guide the development of efficient and environmentally sustainable mAb manufacturing processes. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1566-1573, 2018.

Multi-stage countercurrent process for extracting protein from Antarctic Krill (Euphausia superba).

To systematically study multi-stage countercurrent process for Antarctic krill protein extracting and to optimize the multi-stage countercurrent technology, the solubility of Antarctic krill proteins after multi-step dissolution was explored firstly; multi-step extraction was investigated; and then multi-stage countercurrent system for protein extraction was carried out. In single step extraction, krill-to-water ratio and pH were chosen as 1:10 and 12.5 respectively, in order to extract more protein. In the multi-step dissolution process, the protein solubility of aqueous solution at pH 12.5 was 33.0 ± 0.8mg/mL. Multi-step cross-flow processing testified the feasibility of multi-stage countercurrent assumption. Three-stage countercurrent method using krill-to-water ratio 1:10 extracted, 95.1 ± 0.6% protein from krill, where almost the same water as previous works. The total recovery yield of 67.9 ± 1.6% was achieved after precipitation at pH 4.5.

A Scoping Review of Research on the Cranial Molecular Counter-Current Transfer in Mammals

Various cephalic sites of the molecular transport and counter-current transfer have been identified in mammalian species, including the choroid plexus blood-cerebrospinal fluid barrier (CPB-CFB), the cavernous sinus-carotid rete complex as well as the nasal vasculature exchange pathway. The present literature review has been conducted to incorporate articles highlighting the key findings, conclusions, and the anticipated impact of studies aimed to elucidate the counter-current transfer processes in the brain. Although cephalic sites of the molecular counter-current transport of biologically active substances have been clearly defined and their undeniable importance for neurohomeostatic regulations and reproductive physiology has been recognized, a scarcity of most recent reports have slightly dampened the optimism that in the nearest future these sites will be exploited to their full therapeutic potential.

Neodymium recovery from NdFeB magnet wastes using Primene 81R·Cyanex 572 IL by solvent extraction

The necessity of Rare Earth Elements (REEs) recycling is crucial to minimizing their supply risk and provide an alternative to greener technologies. Hence, the REEs recovery from NdFeB magnet wastes using cationic extractants by solvent extraction technique has been investigated in this research. Due to the difficulty in maintaining the aqueous pH in the industrial counter-current devices when extractants like Cyanex 272 or Cyanex 572 are used, the Primene 81R·Cyanex 572 ionic liquid has been synthesised to overcome this. 99.99% Nd(III) recovery with a purity of 99.7% from an aqueous mixture of Nd/Tb/Dy in chloride medium, the three representative REEs present in the NdFeB magnets wastes, has been achieved after two stages counter-current extraction process using 0.30 M of Primene 81R·Cyanex 572 ionic liquid (1:4 A:O ratio) diluted in Solvesso 100, without any aqueous pH conditioning.

Hydrometallurgical process development for the extraction, separation and recovery of vanadium from spent desulfurization catalyst bio-leach liquors

Abstract The processes of vanadium extraction, separation and recovery from spent de-sulfurization catalyst bio-leach liquor solutions were studied. Spent catalyst processing has mainly two benefits: to protect the environment from the effects of waste and to create wealth from waste. Numerous experimental parameters are optimized. The first step evaluated possible suitable extractant systems, followed by the optimal pH conditions. Feasible extractant systems were screened in the first step. The commercial extractants of LIX 973N, Alamine 336, Alamine 308, Cyanex 272 and D2EHPA were examined. In this study, the initial pH varied from 0.0 to 2.5, and after extraction equilibrium, the measured pH was between 0.1 and 2.8. The developed process involves an examination of the phase ratio effect, the creation of a McCabe–Thiele diagram to extract the isotherm, and counter-current extraction (CCE), all of which were examined and optimized for vanadium. The McCabe–Thiele plots showed that quantitative extraction of the target metal was achievable in extraction stages. The CCE process further confirmed the maximum loading of the vanadium while minimizing interference from other metals. Other processes such as scrubbing and stripping were also established. Hydrochloric acid diluted with water was used as a scrubbing reagent, and its pH was 0.8 ± 0.1. Metal enrichment was achieved at a fivefold greater rate by a continuous counter-current extraction process and finally with ammonium hydroxide, with a vanadium amount as high as much as (2039 mg/L) recovered from a loaded organicphase (5180 mg/L).

Calculation of Countercurrent Extraction Process for Separation of [Sm]/[Pr, Nd] in Hydrochloric Acid Solution using Cyanex 572

Calculation of Countercurrent Extraction Process for Separation of [Sm]/[Pr, Nd] in Hydrochloric Acid Solution using Cyanex 572

Optimization of the Supercritical Carbon Dioxide Separation of Bergapten from Bergamot Essential Oil.

The possibility of following traditional cold-press extraction with the post process continuous separation of bergapten from bergamot essential oil was investigated. A fractionation tower was used in an experiment in which cold-pressed bergamot oil was extracted in a continuous countercurrent process by supercritical carbon dioxide under different conditions. Bergapten is fairly soluble in CO2 in its supercritical phase, in particular at a density of 277.90 kg⋅m-3, corresponding to a pressure of 8 MPa and temperature of 40°C. Under these conditions, an extract with 0.198% bergapten was obtained, a figure slightly below the percentage of bergapten contained in cold-pressed oil (0.21%). However, at densities below 200 kg⋅m-3, the amount of bergapten in the extracted oil was negligible. Of all tested conditions for separation, the best was found to be at a pressure of 8 MPa and temperature of 70°C, conditions under which bergapten was not detected. The results of the experiment showed that bergapten, and the non-volatile fraction in general, was extracted only in small quantities and was not extracted at all with at a CO2 pressure of 8 MPa.

Selective removal of sodium and calcium from low-rank coal – Process integration, simulation and techno-economic evaluation

This paper has addressed the techno-economic feasibility regarding the selective removal of sodium (Na) and calcium (Ca) from low-rank sub-bituminous coal, aiming to reduce the ash slagging and fouling propensity in the pulverized coal-fired boilers. Four novel process integrations were proposed and simulated in Aspen Plus. Both the novel counter-current three-stage water washing process and an acid-water two-stage washing process have proven to improve the ash fusion temperature satisfactorily, reducing the mass fraction of Na2O in ash from 4.32wt% to 0.85 and 0.19wt%, respectively. In addition, the use of acid-water washing removed 12.5% CaO and 19.5wt% total ash. For the recycle and treatment of wastewater, the water gain is desirable for the use of an evaporator, owing to the dewatering of the initially high-moisture coal (25wt%) in the centrifugal and the high water recovery rate from the evaporator. However, the good performance of evaporator was counteracted by the considerable capital cost caused by the huge heat transfer area requirement. Instead, the use of reverse osmosis (RO) resulted in a water loss up to 228.4kg/t coal. Additionally, prior to the RO treatment unit, the recycle and reuse of the unsaturated water for maximum six times and four times for three-stage water washing and acid-water two-stage washing, respectively, was critical in reducing both the water and power consumption. The water consumption dropped to 38.1kg/t coal and 48.1kg/t coal for the three-stage water washing and acid-water two-stage washing process, respectively. Both are remarkably lower than 85.0kg-water/t black coal. In terms of the power consumption, it decreased to ~9.4kWh/t coal for the three-stage water washing process and further down to 5.8kWh/t for the acid-water washing case, which was even slightly lower than 6.3kWh/t for the black coal. Furthermore, the integration of acid-water washing and RO was also demonstrated to be economically viable by its high NPV, IRR and short payback period. Sensitivity analysis indicate that, the original Na content in raw coal is the most influential variable on the water and power consumption of the overall process, followed by the initial moisture content in the raw coal. For a low-rank coal containing >2150–2520ppm Na and/or <19wt% moisture, the washing process proposed would turn economically unviable compared to the existing black coal washing process. A minimum selling price of 136 RMB/t (−32% deviation) was also necessary to keep both NPV and IRR positive as well as the payback period shorter than the project lifetime.

Direct Acid Leaching of Vanadium from Stone Coal

AbstractThis paper focused on optimizing the process conditions of direct acid leaching process to enhance the leaching efficiency of leaching vanadium from the stone coal. Orthogonal experiments and single factor experiments were conducted to investigate the effect of the influential factors of direct acid leaching on vanadium leaching ratio. The results showed that the vanadium leaching ratio reached the maximum value of 89.22 % under the optimal process conditions of CaF2 dosage 5 mass%, H2SO4 dosage 40 mass%, leaching temperature 95 °C and leaching time 10 h. Furthermore, the reaction mechanisms of the main influencing factors were analyzed. Finally, the two-stage counter-current leaching process was adopted to decrease the consumption of sulfuric acid and neutralizer, and the results indicated that the consumption of sulfuric acid decreased 12.50 % as well as neutralizer decreased 35.80 %.

Liquid-liquid extraction for the separation of Co(II) from Ni(II) with Cyanex 272 using a pilot scale Re-entrance flow microreactor

A novel pilot scale microreactor in continuous re-entrance flow was evaluated in selective extraction of Co from Ni sulfate solution with Cyanex 272. The microreactor had three-dimensional (3D) conical sections symmetrically connected in 6 series with an internal volume of 12ml and was capable of handling flow rate of 9l/h. Using this extraction system correlation relating pressure drop and energy dissipation to flow rate was studied. Effects of variation of flow rate/residence time and extractant concentration on extraction and separation efficiency were investigated. The results indicated that high extraction ratio of Co, good selectivity for separation of Co from Ni at low Cyanex 272 concentration were obtained in single-stage microextraction system. Above 99.9% of Co was separated from aqueous phase in two-stage counter-current extraction processes. Moreover, mass transfer performance between the two immiscible phases was investigated and compared to other unstructured microchannels. The overall volumetric mass transfer coefficient kLα of the target Co in the special 3D conical microstructure were superior to other simple microchannels due to the high extraction ratio at short residence time caused by re-entrance flow effect.

Theoretical study of dynamic countercurrent cyclic extraction processes for the separation and concentration of components of a liquid mixture

Some results of theoretical studies on different dynamic countercurrent cyclic extraction variants and the effect of principal process parameters on the efficiency of separation for liquid mixture components have been given. The studies are based on a modified model of the equilibrium stages. It has been established that the proposed extraction mode enables the concentration of target mixture components with their simultaneous separation.

Counter-Current Attrition Process (CCAP) to Remove Metals, Pentachlorophenol (PCP), Dioxins and Furans (PCDDF) from the 1-4-mm Fraction of Contaminated Soil

ABSTRACTThe objective of this study was to evaluate the potential of a counter-current attrition process (CCAP) over 15 cycles for removing metals, pentachlorophenol (PCP) and polychlorinated dibenzo-p-dioxins and -furans (PCDDF) from contaminated soil. The CCAP, applied to the 1–4-mm fraction of a contaminated soil, included five attrition steps (pulp density (PD) = 40% (w w−1), surfactant [BW] = 2% (w w−1), t = 20 min, T = 20°C) followed by one rinsing step. The water emerging from the first attrition step was treated using flocculation in the presence of 0.04 g CMX 123 (commercial flocculent) L−1 before being reintroduced into the CCAP. The CCAP including the treatment of attrition wastewater (ATW) by flocculation achieved a removal of 44 ± 5% As, 26 ± 6% Cr, 24 ± 5% Cu, 49 ± 4% PCP and 45 ± 3% PCDDF. Moreover, the CCAP enabled a significant reduction (78%) in the amount of water required (around 14.5 m3 of water per ton of the 1–4-mm soil fraction). The high removal yields obtained after 15 attrition cycles of the CCAP for PCP and PCDDF and the significant reduction of water consumption confirm that this CCAP can be considered for industrial applications.

Characterisation and removal of organic matter from a reverse osmosis concentrate by a PAC accumulative countercurrent four-stage adsorption-MF hybrid process

A powdered activated carbon (PAC) accumulative countercurrent four-stage adsorption-microfiltration (ACFA-MF) hybrid process was investigated for the removal of dissolved organic matter from reverse osmosis concentrate (ROC). The results showed that based on the same PAC dose, the COD removal efficiency was improved to approximately 70% from 51% for a single-stage adsorption process and from 62% for the PAC accumulative countercurrent two-stage adsorption-MF (ACTA-MF) process, and the DOC removal efficiency increased to >80% from 55% and 70%, respectively. From another perspective, to achieve the same effluent quality (DOC removal efficiency of 83%), the PAC dose for the ACFA-MF process was 58% and 32% lower than that of a single-stage adsorption and the ACTA-MF processes, respectively. In addition, compared to the ACTA-MF process, membrane fouling was effectively mitigated by the ACFA-MF process. XAD-8 and XAD-4 resin fractionation and fluorescence excitation-emission matrix were also conducted to characterize organic matter in the ROC. The main emerging and priority pollutants could be removed in different degrees by the ACFA-MF process.

Phase-field simulation of counter-current spontaneous imbibition in a fractured heterogeneous porous medium

Spontaneous imbibition is well-known to be one of the most effective processes of oil recovery in fractured reservoirs. However, the detailed pore-scale mechanisms of the counter-current imbibition process and the effects of different fluid/rock parameters on this phenomenon have not yet been deeply addressed. This work presents the results of a new pore-level numerical study of counter-current spontaneous imbibition, using coupled Cahn–Hilliard phase field and Navier–Stokes equations, solved by a finite element method. A 2D fractured medium was constructed consisting of a nonhomogeneous porous matrix, in which the grains were represented by an equilateral triangular array of circles with different sizes and initially saturated with oil, and a fracture, adjacent to the matrix, initially saturated with water and supported by low rate water inflow. Through invasion of water into the matrix, oil drops were expelled one by one from the matrix to the fracture, and in the matrix, water progressed by forming capillary fingerings, with characteristics corresponding to the experimental observations. The effects of wettability, viscosity ratio, and interfacial tension were investigated. In strongly water-wet matrix, with grain contact angles of θ &amp;lt; π/8, different micro-scale mechanisms were successfully captured, including oil film thinning and rupture, fluids’ contact line movement, water bridging, and oil drop detachment. It was notified that there was a specific grain contact angle for this simulated model, θ = π/4, above it, matrix oil recovery was negligible by imbibition, while below it, the imbibition rate and oil recovery were significantly increased by decreasing the contact angle. In simulated mixed wet models, water, coming from the fracture, just invaded the neighboring water-wet grains; the water front was stopped moving as it met the oil-wet grains or wide pores/throats. Increasing water-oil interfacial tension, in the range of 0.005-0.05 N/m, resulted in both higher rate of imbibition and higher ultimate oil recovery. Changing the water-oil viscosity ratio (M), in the range of 0.1–10, had a negligible effect on the imbibition rate, while due to co-effects of capillary fingering and viscous mobility ratio, the model with M = 1 had relatively higher ultimate oil recovery.

Extraction of vanadium from direct acid leach solution of converter vanadium slag

ABSTRACTDirect acid leaching of converter vanadium slag by titanium dioxide waste is eco-friendly and efficient, but with low selectivity. This novel technique can result in a vanadium solution which contains chromium(III), aluminium(III), magnesium(II), manganese(II) and high amount of iron(II) and iron(III). Bis (2-ethylhexyl) phosphoric acid (D2EHPA) and tri-butyl-phosphate (TBP) diluted with sulphonated kerosene were applied for vanadium extraction from the multi-element leach solution. The effects of the initial pH, concentration of D2EHPA, ratio of organic to aqueous phase, and the extraction time on the extraction efficiency of vanadium were investigated in saponification and unsaponifiable systems, respectively. The results showed that the vanadium extraction percentage can be up to 97% and the iron extraction percentage can be less than 10% in a thirteen-stage counter-current simulation test and the separation coefficient between vanadium and iron can reach to 109.8. Furthermore, vanadium(IV) can also be separated from other impurities such as aluminium(III), magnesium(II), manganese(II), chromium(III) efficiently. The loaded organic phase was stripped by 184 g L−1 sulphuric acid solution in a three-stage counter-current stripping process and with the total vanadium stripping percentage of greater than 99.5%. In the end, the vanadium pentoxide products with a purity of 99.14% were obtained.

Simulation of counter-current imbibition in single matrix and field scale using radical integral boundary element method

During the water driving process in reservoir which has complex fracture networks, water flows in the fractures and matrix blocks are surrounded by fractures, under this circumstance, spontaneous counter-current imbibition is the dominant mechanism for oil recovery. Therefore, modelling the counter-current behavior properly is such essential when evaluate the production performance of fractured reservoir that contains large amount of water. In this paper, the Radical Integral Boundary Element Method(RIBEM) is firstly introduced to simulate spontaneous counter-current imbibition process, this method successfully transforms the governing equation of counter-current imbibition into the complete boundary integral form and thus the boundary element method can be applied to calculate counter-current imbibition rate, the core advantage of this method is that RIBEM can achieve acceptable results without the need to divid the matrix block into many subgrids, which is convinient for application and reducing a lot computational burden. The validation of RIBEM is tested both on core and field scale, simulated results are in good agreement with corresponding experiment and fine grid simulation data.