Chemical Engineering & Technology最新文献

The Rectisol process plays a pivotal role in syngas purification for clean coal utilization. Feedstock variations during gasification induce syngas flow and composition fluctuations, necessitating adaptive process control. This study develops both proportional–integral–derivative (PID) and model predictive control (MPC) strategies for the CO₂ absorption column. The MPC controller was developed in MATLAB Simulink and innovatively integrated with Aspen Plus Dynamics through the AMSimulation interface module for co-simulation. The control strategies were evaluated under ±10 % flow and ±2 % CO₂ concentration disturbances, with purified gas quality assessed through response time (RT), overshoot (OS), and the integral of absolute error multiplied by time (ITAE). The data-driven MPC strategy exhibits enhanced robustness against flow and composition variations compared to conventional PID control. The study offers actionable guidance for control system design in process industries.

Enameled steel chemical reactor equipment. © gen_A@AdobeStock

To understand the influences of heterogeneous wettability on the microchannel walls on droplet generation, this article proposes a T-junction microchannel with two distinct contact angles on the channel walls (θ₁ on three walls and θ₂ on the fourth wall) to investigate their effects on the droplet generation modes and sizes. A phase diagram illustrating the droplet generation mode across a wide range of θ₁ and θ₂ reveals that increase either contact angle induces a transition in droplet generation modes from no droplet generation to jetting, squeezing, and finally dripping. Notably, a larger θ₁ is required for the stable droplet generation. Furthermore, compared to uniform wettability configuration, reducing θ₂ facilitates the emergence of squeezing mode and jetting mode and yields larger droplets at fixed θ₁. This study provides insights into the design and optimization of microfluidic systems for tailored droplet generation.

Numerous studies have investigated the impact of gels on relative permeability changes. Most of them focus on the reduction of permeability in porous media, which is assessed by examining the increase in pressure required for fluid injection. In this context, F_rrw and F_rro are defined and analyzed for their variations. Besides, gels behave as porous media with respect to water, exhibiting significantly lower permeability compared to water itself. However, when subjected to oil, these gels function as impermeable materials due to the application of injection pressure. As the rate of water injection increases within the porous medium, the value of F_rrw decreases. This decrease does not necessarily correlate with an increase in F_rro; if an increase does occur, it typically does not revert to the original F_rro value observed before the increase. This phenomenon is attributed to irreversible alterations in the gel structure. Consequently, this review examines various types of gels.

The study aimed to optimize the spray-drying process to produce powder from a curcumin suspension (10 g L⁻¹, curcumin-to-pectin ratio of 1:1.5). The suspension was homogenized at 8000 rpm for 40 min, yielding 9.195 g L⁻¹ curcumin with a mean particle size of 5.42 µm and a median particle size of 5.07 µm. Optimal spray-drying conditions were a curcumin-to-maltose ratio of 1:2, an inlet temperature of 170 °C, and a feed flow rate of 15 mL min⁻¹. The resulting powder was compressed into tablets containing 20 mg curcumin, 1 % polyvinylpyrrolidone K30, 3 % crospovidone, 2 % magnesium stearate, and maltose up to 130 mg. Tablets showed a disintegration time of 13 min 25 s and weight uniformity of 0.200 %. Dissolution testing revealed that tablets had slower initial release but higher overall dissolution than other curcumin dispersions.

This study develops a high-temperature-resistant dust suppressant (HTRDS) for railway coal transportation: 0.2 % XG, 0.2 % CMC-Na, 0.09 % PEO, 0.20 % PVA, and 99.31 % water (mass concentration). Electrostatic interactions between components enable polymer chains to form multi-point cross-linking, improving solution stability and viscosity. Hydrogen bonding between polymers and water enhances water retention and promotes uniform water loss, forming a thicker and stronger solidified layer on coal. The results show that the viscosity is 139 mPa·s at 25 °C; the hardness of the solidified layer exceeds 35 HD at 40–60 °C; and the wind erosion rate is only 0.3 % under 12 m·s⁻¹. Moreover, the HTRDS also has an approximately 3.7 % higher environmental degradation rate than the commercial product.

This study employs Aspen Plus to simulate the pretreatment and cold flow of poplar wood in a fluidized bed, revealing key insights into process efficiency and hydrodynamics. The results show that (i) grinding poplar wood results in over 97 % of particles being smaller than 5 mm at a grinding power setting of 2 kWh t⁻¹, requiring 1.3 kW of power for a processing quantity of 500 kg h⁻¹; (ii) drying poplar wood with an initial moisture content of 20 % can be achieved by using hot air at 3000 kg h⁻¹ and 150 °C, poplar wood reaches a moisture content of 6.6 % and a temperature of 50.4 °C after drying, and the overall drying process necessitates a total energy input of 110.6 kW, alongside a heat loss of 3.9 kW for drying 500 kg h⁻¹ of poplar wood; (iii) the minimum fluidization velocity requires 0.147 m s⁻¹ and the overall pressure drop reaches 2.083 kPa when 433.6 kg h⁻¹ poplar wood particles undergo fluidization with 600 kg h⁻¹ nitrogen.

Oil pollution in aquatic systems remains a major global issue, especially due to bilge water discharges that may exceed the 15 ppm oil-in-water (OiW) threshold set by the International Maritime Organization (IMO). In this study, an improved fluorescence imaging method is presented for quantifying oil concentration and simultaneously characterizing droplet distributions in dynamic emulsions. OiW emulsions of four different oil types were prepared without chemical stabilizers in a range from 5 to 100 ppm. The images were processed with custom algorithms to determine fluorescence signal, droplet number, and size distribution. The calibration showed a strong linear correlation between fluorescence and oil concentration (R² = 0.967–0.999).

The change of particle shape is a side effect in the comminution process; however, in some cases, the main objective of the comminution process can be the modification of particle shape as well. The particle shape modification can be achieved during the reduction of the particle size and without significant particle size decrease as well. The different cases of targeted particle shape modification and their applications were discussed, and the evaluation of the process by particle shape distribution and by efficiency parameters was demonstrated for brittle-like minerals and non-brittle waste materials as well.