Chemical Engineering & Technology最新文献

This study addresses the service life reduction issue in progressive cavity pumps (PCPs) caused by increased interference values by proposing an optimized design method incorporating a variable-diameter rotor structure. Through sensitivity analysis of interference values, critical vulnerable areas of the pump were identified, and the design theory of the variable diameter rotor was proposed. Finite element simulation results demonstrate the effectiveness of this approach, with particularly notable optimization effects under high-speed and high-viscosity operating conditions. The variable-diameter rotor design provides both novel theoretical foundations and practical guidance for performance optimization of PCPs, representing a rational and effective design approach.

The reversible nature of the reaction between CO₂ and amines results in finite partial pressure of CO₂ over the aqueous amine, thereby establishing a state of vapor–liquid equilibrium (VLE). Knowledge of the equilibrium features is essential for the design and operation of CO₂ absorbers. This high-pressure equilibrium study provided CO₂ solubility vs. CO₂ partial pressure data for three amines, viz., ethylene diamine (EDA), N-ethylethanolamine (EEA), and N,N′-diethylethanolamine (DEEA). The dependence of solubility on amine molarity was studied at 308, 318, and 328 K in the 2–3.5 M range. Equilibrium CO₂ solubility was lowered when the temperature increased. It improved when amine molarity in solution was increased. It was found that DEEA loaded more CO₂ upon promotion with EDA and EEA. Mixtures of DEEA/EDA and DEEA/EEA achieved a loading capacity around 1 mol mol⁻¹. Empirical equations were developed using the least square regression method, and they predicted solubility data satisfactorily for CO₂ partial pressures up to 2500 kPa.

This study investigated the flow behavior of Leidenfrost droplets on a heated plate with a hydrophobic coating. The treatment increased the contact angle from 76° to 120° and slightly enhanced surface roughness. On untreated surfaces, the evaporation time peaked at 260 °C, whereas treated surfaces showed a linear evaporation trend with a reduced Leidenfrost temperature of 140–160 °C. This suggests earlier vapor film formation due to enhanced bubble nucleation. Microscopic observation confirmed droplet levitation at 140 °C. Particle image velocimetry (PIV) analysis showed that internal flow velocity increased with temperature and was higher on treated surfaces. These results demonstrate that water-repellent treatment lowers the Leidenfrost temperature and enhances flow, offering potential for low-temperature droplet-based reactions.

In this paper, an integrated agent named TSE containing surfactants, such as cetyltrimethylammonium chloride (CTAC), sodium aliphatic alcohol polyoxyethylene ether sulfate (AES), and dodecyl dimethyl betaine (BS-12), was composed and employed as oil field additive with dual functions: foam drainage and hydrate anti-agglomeration. The results show that the optimized formula achieved an initial foam volume of 565 mL with a long half-life of 7–8 min. No settlement and stratification after 24 h further confirm the well stability of the formed foam. Good salt and methanol resistance of TSE can be found even the addition of methanol and sodium chloride. Moreover, it was demonstrated that TSE exhibited a comparable high liquid carrying rate of 77.5 wt% at 65 °C even in the presence of kinetic hydrate inhibitor. The reduction of hydrate phase transformation point indicates TSE well thermodynamic properties.

Addressing high energy use and inefficient distillation in methanol production, this study innovatively integrates modeling, dividing-wall column (DWC) technology, and energy optimization for a 400 000 t/a plant. Developed integrated synthesis-distillation model replaces traditional atmospheric column with DWC. Process simulation optimized key parameters: pressure, temperature, recycle ratio, feedstock (CO₂/CO), and water dosage. A DWC dynamic control system ensured stability, whereas plant-wide energy optimization was implemented. Results: DWC boosted top-product methanol yield 9.22 %, total output 5.14 %, and cut fusel oil methanol 62.73 %. Energy optimization reduced utilities 35.63 % (heating −36.69 % and cooling −34.59 %), raised inter-stream heat recovery 4.85×, and lowered emissions 42.29 %. Strong economics: NPV > 0 and IRR > 12 %. This process effectively reduces energy consumption and improves yield, providing a feasible solution for clean production of industrial methanol.

In this paper, based on the heart-shaped microreactors (Advanced Flow Reactor, AFR), the asymmetric heart-shaped passive microreactor is designed. The length ratio (Ratio = L₀/L) is defined as a measure of asymmetry. L₀ is the length of the baffle in the minor sub-channel, and L is the length of the baffle in the major sub-channel. The total length of the baffle is L_t (L_t = L₀ + L). For unchanged L_t, the mixing index obtained from the asymmetric heart-shaped passive microreactor under the conditions of Ratio = 0.767 and Re = 100 is 53.86 %, which is 9.44 % higher. For changed L_t, at Re = 6, the mixing is dominated by diffusion mixing, and the standard error of the mixing index among heart-shaped passive microreactors with different Ratio is within 0.05 %; at Re = 60, the mixing is dominated by convective mixing. The mixing index of asymmetric heart-shaped passive microreactor with Ratio = 0.8 can reach 0.4386, which is 2.6 % higher; at Re = 100, the mixing index increases by 2.86 %.

Leaf alcohol is typically produced through batch selective semi-hydrogenation of 3-hexyn-1-ol using Lindlar catalyst. Although several catalysts have been described for this transformation, they are manufactured on a gram scale, posing challenges for industrialization. We decided to implement this process in flow. We show that, in the absence of quinoline, precise control of the reaction's progress is crucial for achieving high selectivity. To reduce the pressure drop, the catalyst was pelletized using CaCO₃ as a binder. At 40 °C and under 1 bar of H₂, total conversion was obtained in less than 1 min. However, selectivity at high conversion is lower due to mass transfer limitations and a broad contact time distribution. Selectivity can be enhanced by increasing the liquid flow rate, whereas high conversion can be attained by operating in a recirculating flow mode. Under this configuration, high selectivity at high conversion can be achieved in flow using a commercial Lindlar catalyst.

Natural pigments of microbial origin have attracted industrial interest due to their safety profile, environmental compatibility, and lack of carcinogenic effects. This study aimed to optimize the extraction of chlorophylls and carotenoids from Dunaliella salina, which was cultivated in bubble column photobioreactors, followed by biomass harvesting and ethanol-based extraction assisted by probe ultrasound. A 2² factorial design was used to assess the effects of extraction time and ultrasound cycle. Results showed that extraction time significantly influenced all pigment extraction, favoring shorter durations, whereas the cycle was significant only for chlorophylls. The extraction conditions also enabled the recovery of β-carotene, indicating a substantial production of pigments.

Mixed amine solvents provide an efficient solution for capturing CO₂ from refinery emissions. They offer improved absorption and reduced energy use compared to using traditional solvents such as monoethanolamine (MEA). However, selecting the optimal blend tailored to the specific composition of refinery emissions is complex and time-consuming. This study develops an optimizer based on the Aspen Platform to identify the optimal mixed amines from >500 possible combinations. The resultant amine blend obtained is a combination of methyl diethanolamine (MDEA)/piperazine (PZ) (39 wt%), demonstrating more than 95% CO₂ capture. The blend also showed a significant reduction in energy (min 20%) because of decreased steam consumption for solvent regeneration.