Chemical Engineering & Technology最新文献

Air separation processes are time-consuming and energy-intensive. Most of the energy used in air separation unit (ASU) is used for air compression. During the air compression process, some energy is lost, which is converted into waste heat. This wasted energy is used to warm liquefied natural gas (LNG). At some point, LNG ships will dock at an LNG regasification facility. Here, LNG is converted back to gas and supplied to the distribution and transmission systems. During the regasification process, cryogenic LNG has a huge opportunity for cold energy recovery. An innovative air separation process that is integrated with the cold utilization of LNG is presented in this study along with a thorough conceptual design and analysis. The results of this study show that producing high-purity oxygen and nitrogen, respectively, requires 0.28 kWh kg⁻¹ and 0.06 kWh kg⁻¹ of specific energies. Prior to integration with cold utilization of natural gas, 25 141.6 kW is needed for air compression. However, following integration, 10 554.6 kW of energy is needed, resulting in a 58.01 % energy savings. Exergy destruction as well as efficiency have been calculated for the primary components of the system. Sensitivity analysis is carried out to examine the effects of LNG streams on important parameters. In conclusion, a cryogenic ASU is integrated with an LNG-direct expansion cycle-organic Rankine cycle power cycle to supply the necessary power for operation and reduce extraneous power inputs. Overall, this integrated approach increases efficiency, lowers costs, benefits the environment, allows for flexibility and adaptability, and raises system dependability.

Copyright: © Crystal Kwok @ Unsplash

A Box-Behnken design was used for the analysis using a gray wolf optimizer (GWO)-coupled artificial neural network (ANN) model and response surface methodology (RSM) to analyze the effect of three operating parameters (volumetric exchange ratio [VER], aeration rate [AR], and cycle time [CT]) manipulated during an aerobic granular sludge process (AGS) sequencing batch reactor on modeling the removal of chemical oxygen demand (COD) in mixed wastewater. The most efficient architecture for COD showed the highest efficiency for modeling the AGS. The RSM model and plot results indicate that the CT and AR were the most influential on COD removal efficiency. When compared with models with statistical indices, GWO-ANN demonstrated higher performance compared to RSM.

In response to escalating environmental concerns and the imperative to institute effective energy management strategies, the pursuit of alternative fuels has emerged as a pivotal endeavor for realizing sustainable energy solutions. Methanol and ammonia have surfaced as particularly promising and environmentally friendly liquid fuels, holding significant potential for aiding in the attainment of decarbonization objectives and addressing global energy requirements. This research proposes and scrutinizes a sophisticated cogeneration system integrating solid oxide fuel cells (SOFCs), gas turbine (GT), steam Rankine cycle, and organic Rankine cycle. Direct utilization of ammonia and methanol as fuel in this intricate system is examined, with the design and modeling facilitated through the utilization of Aspen HYSYS V.12.1. The thermodynamic performance of the proposed system is rigorously assessed by employing the foundational principles of the first and second laws of thermodynamics. The direct SOFCs fueled by ammonia and methanol exhibit notable energy efficiencies of 64.25 % and 58.42 %, respectively. Remarkably, the amalgamated systems showcase heightened energy efficiencies, witnessing a commendable increase of 12.64 % and 10.66 % when powered by ammonia and methanol, respectively, as compared to individual SOFC systems. Examination of exergy destruction reveals the SOFC as the principal contributor, with electrochemical and chemical processes constituting the primary sources of irreversibility. Additionally, explicit values for exergy destruction in the GT, afterburner, and heat exchanger components are provided. A comprehensive parametric study underscores the pivotal role of the fuel utilization factor (U_f), identifying a value of 0.85 as optimal and significantly augmenting the thermodynamic efficiency of the system. This analysis not only substantiates the potential of ammonia and methanol as effective carriers for hydrogen but also underscores the efficacy of waste heat recovery as a viable strategy for enhancing the overall thermodynamic performance of an SOFC system. The findings presented herein contribute valuable insights, paving the way for the strategic utilization of alternative fuels and cogeneration systems in the broader context of sustainable and environmentally conscious energy solutions.

The assessment of the explosibility and severity characteristics of Bayan coal and Tanito coal was investigated over various concentrations in a 20 L Siwek spherical explosion chamber. The coals tested in this study were also compared with other organic dusts such as palm-based soap noodle, tea powder, black rice, and rice flour, which were tested using the same explosion chamber and procedures. The severity and explosibility of the coals increase as their concentration increases. The P_max of Bayan coal (10.15 bar) is higher than that of Tanito coal (7.35 bar). The K_st of Bayan coal (48.04 bar m s⁻¹) is also higher than that of Tanito coal (16.83 bar m s⁻¹). Among all the dusts studied using the same chamber and procedures, palm-based soap noodle has the highest P_max at 16 bar, while tea powder has the lowest P_max at 6.35 bar. The results show that the explosibility and severity of the coals increase as the concentrations increase, and the moisture content, coal ranking, and different types of organic dust have a significant influence on the severity characteristics of dust explosions.

In this paper, the seeded batch cooling crystallization of sodium phosphite (SP) is simulated and optimized through a coupled method of the genetic algorithm and nonlinear programming. At first, the modeling and simulation test methods of the crystallization process are applied for the crystallization of SP, which expands the relevant study of SP from the experiment to the simulation. A comprehensive model is established in MATLAB/Simulink, and based on this model, the results of the common cooling strategy (linear cooling) on the process are investigated. Meanwhile, the process sensitivity to the change of seeding conditions is analyzed. Then, the coupled optimization method based on the genetic algorithm and nonlinear programming is applied to optimize the crystallization process for the first time, and the obtained optimized cooling strategy is compared to the result of the traditional nonlinear programming method (NLPM). The traditional NLPM has more significant effects on large seeding mass and small mean size, while the coupled method has better adaptability. When the coefficient of variation is almost fixed, the cooling strategy obtained by the coupled method could produce more crystals with large mean size. In addition, the end of the process can be reached earlier. The results show that the coupled method is more suitable for the optimization of the batch cooling crystallization of SP.

LiNi_1/3Mn_1/3Co_1/3O₂ (NMC 111) materials show promise as cathodes for lithium-ion batteries (LIBs). However, their widespread use is hampered by various technical challenges, including rapid capacity fading and voltage instability. The cathode materials synthesized using the combustion method were annealed at various temperatures ranging from 650 to 900 °C for 24 h. In this study, we identified an optimal annealing temperature of 750 °C for LiNi_0.3Mn_0.3Co_0.3Ti_0.1O₂ (NMCT) materials. NMCT-750 exhibits an initial discharge capacity of about 140.1 mAh g⁻¹ and retains the capacity of 91 % after 30th cycles. The good performance of NMCT-750 is directly attributed to reduced cation mixing and the establishment of a stable structure with small particle sizes. In contrast, higher annealing temperatures (850 °C) lead to a rapid increase in primary particle size and result in poor cycling stability. Therefore, NMCT-750, annealed at 750 °C, holds great potential as a cathode material for the next generation of LIBs.

In the present work, a ZnS:Ni loaded on sponge-activated carbon (SAC) was synthesized and applied as an effective adsorbent to remove bromophenol blue (BPB) dye from aqueous solutions. Various techniques such as Fourier-transform infrared, X-ray diffraction, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) were used to characterize ZnS:Ni–SAC. The effective parameters such as BPB concentration, amount of ZnS:Ni–SAC, ultrasonic time, and pH of the aqueous solution were investigated and optimized by response surface methodology. To investigate the accuracy and reliability of the proposed method, the analysis of variance was used based on p-values and F-test. The optimal values of the parameters were obtained using the desirability function, and they were as follows: 15 mg L⁻¹ BPB concentration, 20 min sonication time, 18 mg of ZnS:Ni–SAC, and pH = 7. To evaluate the adsorption mechanism and calculation of maximum adsorption capacity, different adsorption isotherms were studied, and according to the obtained results, the Langmuir isotherm model showed the highest compatibility due to its higher R² (0.997). Also, the proposed adsorbent represented good adsorption capacity (125 mg g⁻¹). Moreover, kinetic studies proved the applicability of the pseudo-second-order model (R² = 0.986) compared to other models. The achieved results confirmed the applicability of ZnS:Ni–SAC as a versatile adsorbent for the removal of BPB.