Asia-Pacific Journal of Chemical Engineering最新文献

This study combined numerical simulation and experiment to explore the influence of the concave-wall jets with uniformly distributed tangential inlets in the cyclone separator on the liquid–solid separation characteristics and equipment. The results show that as the number of tangential inlets increases, the superposition effect of particle trajectories and flow fields becomes more significant. The superimposed flow field enhances the circumferential flow velocity of the fluid, causing the distribution of the jet along the radial and spanwise directions to shrink, greatly improving the uniformity of particle distribution and turbulent kinetic energy along the circumference, and effectively reducing the impact of particles on local areas near the jet inlet. Since the superposition of circumferential multi-inlet jets enhances the swirling flow, the local disturbance and wall erosion effects near the jet inlet were reduced. Compared with double inlets, the flow rates of three inlets and four inlets were increased by 50% and 100%, respectively, the maximum turbulent kinetic energy increased by 14.5% and 56.2%, and the maximum escape time of particles was shortened by 3.2 and 3.3 s, respectively, the maximum erosion rates were reduced by 38.4% and 23.6%, respectively, and the separation efficiency and material handling capacity were significantly improved. This study supplemented the theory of concave-wall jets' superposition characteristics and provided a theoretical basis for applying circumferential multi-inlet devices in liquid–solid separation equipment.

Starch blended low-density polyethylene (LDPE) has been extensively used to produce packaging film, but it has very low mechanical properties. This work emphasises the extraction of nanosilica from rice husk as a property-enhancing filler for producing high-quality packaging material. Nanosilica (200 nm) was obtained by chemical treatment followed by further size reduction through cryomill. The obtained nanomaterial was found to have a high surface area (189.64 m²/g) and pore volume (.462 cc/g) with high compatibility with the other materials in the matrix. The SEM and TEM analysis indicates the uniformity in particle size of the nanomaterial with an agglomerating tendency. The X-ray diffractometer (XRD) and fourier transform infrared spectroscopy (FTIR) analysis reveals that the obtained material is amorphous in nature. The nanomaterial is dispersed in various proportions in LDPE/starch matrix, and it is observed that the highest tensile strength (9.62 MPa) can be obtained at 1.5% nanosilica content in the matrix. A continuous increase in Young's modulus and stiffness from 372.3 to 440.12 MPa and 20 243.2 to 28 559.42 N/m, respectively, when 1.5% of nanosilica is dispersed in the biodegradable matrix. Garden soil was a better degrading medium for the sample containing 20% of starch with weight loss of 10.32% and reduction of tensile strength and tear strength values to 5.987 MPa and 99.165 N/mm respectively, in 1 year.

The influence of circulating liquid velocity on bubble size distribution (BSD) and turbulence characteristics of an external loop airlift reactor was studied in this paper. The instantaneous and time-averaged velocity in the riser were studied using particle image velocimetry (PIV), and BSDs were measured by digital image analysis technique based on machine learning. Then turbulence kinetic energy (TKE) and energy dissipation rate (EDR) were calculated through the velocity field. The results indicate that as the circulating liquid velocity increased, the peak value of BSD rapidly decreased from nearly 6 mm to approximately 2 mm. The radial velocity of the liquid gradually decreased and changed direction, eventually increasing again. TKE first decreased and then increased. Compared with bubble flow with a BSD peak of 2–6 mm, bubble flow with a BSD peak of 2 mm had larger TKE. The radial movement of bubbles had great influence on the turbulence characteristics. This study demonstrates that selecting an appropriate circulating liquid velocity can reduce the diameter of bubbles while obtaining greater TKE, thereby improving the mass transfer and reaction efficiency in external loop airlift reactors (EL-ALR).

The separation process is a well-established method for beneficiation technologies of low-rank coal, especially in the case of utilization in the thermochemical processes. In this study, three coal samples, including the original low-rank coal sample and two coal samples (C1 and C2) from the gravity separation process of the original coal sample, were gasified in a multi-stage gasification process at the gasification temperature of 900°C and the steam-to-carbon (S/C) ratio of 1.00 and 1.25. The separation process led to a significant improvement in the quality of coal samples. This improvement is particularly characterized by a higher carbon and volatile fractions and a lower ash content compared with the original coal. This could be the main reason for the higher gasification performance in the case of the experiment of C1 and C2 coal samples. The volume of syngas obtained from gasification experiments of C1 and C2 samples increased between 1.3 and 1.5 times that of the original coal sample. At all S/C ratios and 900°C, the gasification experiment of the C2 sample produced the highest produced gas yield followed by the gasification experiment of the C1 sample. From the chemical point of view, the produced gas had an H₂/CO ratio close to the desired ratio of 2.00, which is suitable for chemical synthesis processes. In the case of C1 sample experiments, the H₂/CO ratios were 2.11 and 2.18 at S/C ratios of 1.00 and 1.25, respectively. For the experiments of the C2 sample, the H₂/CO ratio reached 1.88 and 2.00 at S/C ratios of 1.00 and 1.25, respectively.

Degumming and bleaching are critical steps in the palm oil refining process, as they are the precursors to the qualities of refined, bleached, and deodorized palm oil. In practice, plant operators often face oil rejections in these processes and solve the problem by trial and error. Hence, a fuzzy expert system is developed to troubleshoot the degumming and bleaching process, for identifying failures and suggesting actions. However, developing the knowledge base and inference engine in the fuzzy expert system for troubleshooting the degumming and bleaching process is challenging because the data in the actual palm oil refining process are poorly documented and must be obtained from various sources, including field observation, document analysis, and interviews, and need to be analyzed using thematic analysis. The results from the thematic analysis were represented as input and output variables of the fuzzy expert system. The developed fuzzy expert system is tested and validated against different data sets and industrial data to identify faults and suggest necessary actions. To evaluate the robustness of the troubleshooting system, the membership functions of the fuzzy expert system are adjusted based on the distributed control system (DCS). The results show that the troubleshooting system can effectively diagnose potential faults and provide necessary actions and can serve as a useful guidance for failures in the degumming and bleaching process.

This work comprises ternary systems of water + SAIL,1-decyl-3-methylimidazolium bromide, and (S)-2-Amino-3-methylbutanoic acid generally identified as L-valine/ (S)-2-(2-Aminoacetamido)-3-methylbutanoic acid usually described as glycyl-L-valine, densities, and sound speed data have been computed at four operating temperatures, i.e., 288.15 to 318.15 K. Calculated density data have utilized for calculation of various thermodynamic parameters like V_ϕ (apparent molar volume), $�V_{\varphi }^0$ (apparent molar volumes at infinite dilution), and calculated speed of sound statistics used to determine K_ϕ,s (apparent molar isentropic compression), K_s (partial molar isentropic compression at infinite dilution). In our systems, the hydrophilic-ionic interactions that are produced by co-sphere overlap models are predominant. The Hepler's constant is used to analyze the solute's capacity to create or destroy solvent structures. The interaction parameter is computed using the McMillan-Mayer theory. Understanding structure-making, solvation characteristics, and numerous modifications in the ternary system of L-valine/Glycyl-L-valine, water, and [C₁₀MIm] [Br] is aided by a variety of thermodynamic factors.

The increasing demand for boron has resulted in its contamination of water supplies. Nanofiltration membranes, particularly thin-film nanocomposite (TFN) membranes, have shown promise in removing contaminants. This study evaluated the boron removal capabilities of negatively and positively charged TFN membranes alongside a control thin-film composite (TFC) membrane without nanoparticles. Piperazine (PIP, for negatively charged membrane) or polyethyleneimine (PEI, for positively charged membrane) aqueous monomer was reacted with trimesoyl chloride (TMC) in n-hexane solution via interfacial polymerization (IP) on the polyethersulfone (PES) membrane substrate to form the TFC membrane. During the TFN membrane preparation, titanium dioxide (TiO₂) and sulfocalix[4]arene (SCA4) were introduced as active nanoparticles to the aqueous monomer. Boron removal performance was evaluated using a 10 ppm aqueous boron solution. The PES substrate gave the highest water flux, which was 307.80 LMH. For the TFC membrane, TFC–PIP had a higher water flux at 113.71 LMH than TFC–PEI. Furthermore, the TFN membranes containing the PEI monomer had a lower water flux than those containing the PIP monomer. These findings highlight the potential of TFN membranes, particularly those incorporating nanoparticles, for effective boron removal. Further research and optimization of TFN membranes can contribute to addressing the challenge of boron contamination in water supplies.

The maximum utilization of hydrocracking tail oil becomes increasingly important for petrochemical industry. The aim of this work is to develop optimized distillation processes to achieve various high-valued qualified oil products from hydrocracking tail oil. Six different oil products is produced and the steady-state distillation process, which aims to fractionate six qualified narrow distillates is established. The algorithm method incorporating divided-wall column (DWC) configuration was introduced into the steady-state design. Compared with traditional separation sequences, the DWC configuration leads to an energy-saving potential up to 11.17%. Furthermore, effective dynamic control strategies were proposed, demonstrating precise and efficient control performance. In the presence of a 15% feed disturbance, the dynamic control structure is capable of maintaining the product distillation range near the set value. This comprehensive study provides a thorough investigation into the efficient utilization of hydrocracking tail oil, establishing a robust theoretical foundation for its industrial application.

An improved hydrothermal method was proposed to rapidly synthesize zeolite W from alkali fusion-activated K-feldspar. The effects of m (KOH)/m (K-feldspar), n (SiO₂)/n (Al₂O₃), n (H₂O)/n (SiO₂), crystallization time, and crystallization temperature on the synthesis of the zeolite W were investigated. The optimal synthesis conditions were m (KOH)/m (K-feldspar) ratio of 1.5:1, the activation time of 2 h, and the activation temperature of 500°C, n (H₂O)/n (SiO₂) ratios of 42, n (K₂O)/n (SiO₂) of 0.90, n (SiO₂)/n (Al₂O₃) of 5, crystallization time of 6 h, and crystallization temperature of 150°C. The mechanism for rapid synthesis of zeolite W was illustrated. In this process, Na₂SiO₃·9H₂O and Al₂(SO₄)₃·18H₂O were first dissolved rapidly in the synthesis system to form an amorphous gel, which contributes to the accelerated crystallization process. Compared with the state-of-the-art synthesis method, this method remarkably decreases the water content to be added in the synthesis process and crystallization time, avoids the pre-preparation process of the xerogel, and enhances the utilization rate of K-feldspar. This work provides an industrial-friendly synthesis process of zeolite W and could realize the highly efficient utilization of K-feldspar.

The flow field of a hydrocyclone was investigated using both computational fluid dynamics (CFD) and particle image velocimetry (PIV). A refractive index matching method was employed to improve the precision of the PIV measurements. The CFD results are in good agreement with PIV measurements. Detailed analysis reveals significant axial asymmetry in the velocity components, with the radial velocity component exhibiting notable disparities. This observation is supported by quantitative data comparing different sections of the hydrocyclone. It is further found that the asymmetry might be mainly attributed to the secondary vortexes with the single inlet of the hydrocyclone. And the secondary vortexes, superimposed on the primary flow rather than existing on its own, spiral downwards from near the inlet towards the underflow orifice. It is hypothesized that specific boundary effects and pressure gradients play a pivotal role in the formation of secondary flows. This assumption is grounded on both theoretical considerations and empirical observations, suggesting that these factors significantly influence the flow dynamics within the hydrocyclone. The insights gained from our measurement methodology and enhanced understanding of secondary flows within hydrocyclones are not only poised to serve as valuable references for fellow researchers but also have the potential to inform the design and operational optimization of hydrocyclones for improved efficiency and performance.