Chemical Engineering Science最新文献

All-purpose materials with on-demand oil/water separation property have received broad attention recently. Herein, a filter paper (FP)-based filter with asymmetric wettability was designed and fabricated via simple combination of liquid phase reduction route with symmetry adhesion method. The fabricated filter exhibits underoil superhydrophobic (UOSHP) and underwater superoleophobic (UWSOP) property. Especially, the good underliquids lyophobicity is still maintained after tape peeling and corrosive, organic solvents treatments. By fixing the hydrophobic (HO) side of filter facing up, the water/light oil mixtures and oil-in-water (O-in-W) emulsions can be highly efficient separated, and the water/heavy oil mixtures and water-in-oil (W-in-O) emulsions are able to be separated with the HI side facing up. The separation efficiencies for water/oil mixtures and oil/water emulsions are higher than 98% and 99.1%, respectively. The study offers a new idea for the preparation of asymmetric superwetting materials with good stability and on-demand water/oil separation capability.

Insufficient understanding of complex flow structures in multi-shaft stirred reactors hinders industrial adoption. In this work, Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) methods were used to analyze the Large-Eddy Simulation (LES) results of the stationary and rotating zones for three types of stirred reactors, including multi-shaft configurations. The results indicate that the flexible spatial distribution of the impellers in multi-shaft stirred reactors enhances fluid interactions, leading to the superior performance in energy cascading, flow field self-regulation, and wave-vortex coupling. Frequency analysis of single modes underscores DMD’s efficacy in interpreting complex flow phenomena. Based on this, the DMD modal coefficients were fitted to equations, clarifying the development process of wave-vortex coupling within the stirred reactors. Additionally, by integrating fundamental fluid mechanics equations with the outcomes of the DMD method, a wave-vortex coupling model was developed, which is anticipated to yield a more accurate representation of the flow field.

In order to resolve the pressure checkerboard field problem with collocated grid, it is essential to employ the momentum interpolation method when formulating the pressure equation, and the flux reconstruction method when updating the cell-centered velocity fields. In this study, we first derive a momentum interpolation method for Euler-Euler simulation of gas-solid flows, which is independent of the time step, the transient term discretization scheme, the under-relaxation factor and the shape of grid; a complete first-order flux reconstruction method is then proposed to update the cell-centered velocities. Their effectiveness are proved by simulating the hydrodynamics of solids settlement, gas-solid fixed bed, bubbling fluidized bed and circulating fluidized bed riser, and then comparing the simulation results to the theoretically known solutions. Their superiority over the standard solver of OpenFOAM® in suppressing the high-frequency oscillations and enhancing the smoothness and accuracy is also proved. Finally, the difficulty in fully eliminating the high-frequency oscillations is attributed to the insufficiency of current methods in handling the situations where the independent variables undergo abrupt change.

This work provides a method for the separation and extraction of bromine salts from bromine-containing wastewater by crystallization. Wastewater from the production of 1-Bromooctane is rich in potassium and bromine salts. This will allow for the recycling of chemical resources in this aqueous salt system. Based on the need for the process design of the new method, the solubility phase equilibrium of the quaternary K⁺,NH₄⁺//SO₄^2-,Br^-–H₂O system at 298.15 K and 323.15 K was investigated in this paper by using the isothermal dissolution equilibrium method, and the dry basis phase diagrams were plotted using the experimental data. And the equilibrium solid phase composition was determined by X-ray diffraction. At 298.15 K, the dry phase diagram of the quaternary system K⁺,NH₄⁺//SO₄^2-,Br^-–H₂O consists of three invariant points and five crystalline regions (K₂SO₄, (NH₄)₂SO₄, (K,NH₄)₂SO₄, (K,NH₄)Br, (NH₄,K)Br). At 323.15 K, there is one invariant point in the phase diagram of this quaternary system and three crystalline regions((K,NH₄)₂SO₄, (K,NH₄)Br, (NH₄,K)Br). The (K,NH₄)Br crystallization zone grows while the (NH₄,K)Br crystallization zone decreases with increasing temperature, according to comparisons of the dry basis phase diagrams of this quaternary system at different temperatures. Crystallization zones of solid solution (K,NH₄)₂SO₄ replaced the K₂SO₄ and (NH₄)₂SO₄ single salt crystallization zones at the same time. The Pitzer model was used to calculate the solubility of this quaternary system at 298.15 K. The results showed that the experimental values were in good agreement with the calculated values. Based on the theoretical analysis of the dry phase diagram of the quaternary system K⁺,NH₄⁺//SO₄^2-,Br^-–H₂O, a process route for salt extraction using bromine-containing wastewater generated from the production of 1-Bromooctane was proposed and designed. The new process was experimentally verified to be technically feasible to obtain NH₄Br with 99.01 % purity and (K,NH₄)₂SO₄. The process has significant advantages, such as production safety, low input costs and no three-waste emissions.

Salt crystals fouling may lead to the blockage of debrining inner tubing(DIT) for underground gas storage(UGS) salt cavern. In this paper, the components of salt crystals are analyzed, and a model for calculating the salt crystals fouling is established, which considers the coupling effects of flow-thermal-chemical. This model is verified by comparing monitoring data of an actual salt cavern debrining. The influences of salt cavern depth, DIT size and heat conductivity on salt crystals fouling rate are analyzed. When the salt cavern depth is increased from 1000 to 2000 m, the salt crystals fouling rate increases from 3.61 to 32.17 mm/day. The influences of the DIT size on the salt crystals fouling rate are minor. When the heat conductivity of tubing decreases from 4 to 0.4 W/(m·℃), the salt crystals fouling rate reduces by 30.37 %. This study could help formulate a debrining scheme to prevent the DIT clogging.

We report a simulation-based investigative study of a single-stage, 4-step temperature swing adsorption (TSA) process adopting direct steam heating and direct air (nitrogen) cooling using a hydrophobic MOF physisorbent CALF-20 for post-combustion CO₂ capture (PCC) from wet flue gas. This is a significant departure from our previous TSA-based PCC studies (Peh et al., 2022, Peh et al., 2023), where indirect heating and cooling were used in shell-and-tube type adsorbers. The process investigated here is similar to the Svante process combining the VeloxoTherm^TM rapid cycle TSA rotary adsorber technology with its proprietary structured laminated adsorbent sheets made from CALF-20. The Svante process has been tested in a 0.1 tonnes per day (TPD) facility to demonstrate long-term stability and stable high performance for CO₂ capture from a representative flue gas feed. Very high productivity while meeting the purity-recovery targets is particularly noteworthy. In addition to the superior adsorbent properties of CALF-20 that make direct steam heating possible, the parallel channel structure laminated with very fine adsorbent particles allows many fold increase in mass transfer rate and reduces flow resistance. Comparisons with the performance of CALF-20 in a packed bed configuration show that productivity enhancement is mainly contributed by the parallel passage flow arrangement, which relaxes the velocities in various steps limited by fluidization in a packed bed.

Catalytic-aided combustion is a proven technique for burning highly lean and ultra-lean mixtures of hydrogen and air. However, the noble catalyst required for combustion is naturally scarce and therefore expensive. In this study, we focus on a numerical investigation to determine the best way of coating a platinum catalyst inside a catalytic hydrogen reactor. We study various planar and non-planar reactors and find that the reactor with a combination of half and full cylinders is the most effective in H₂ conversion. Compared to an equivalent catalytic planar reactor, the non-planar configuration increases the H₂ conversion by 30.7 %. The results show that enhancing mass and heat convection can significantly increase the H₂ conversion. Furthermore, in a non-planar reactor, surfaces with an enhanced mass and heat transfer can achieve up to 50 % catalyst savings when coated with a catalyst, while still maintaining a conversion rate of 2 kg/s per unit of catalytically-coated surface area.