Canadian Journal of Chemical Engineering最新文献

Inherent safety concepts are common knowledge today, but accidents with similar characteristics do recur. Research on accident causes found that design errors, especially equipment failure, contribute the highest percentage of accidents. The development of inherent safety tools has been increasing at a positive pace, but only a small number of these tools are applicable to equipment design. Ample amounts of inherent safety tools are only suitable to be used at the early design stage. This amplifies the fact that inherent safety tools are still conceptual (e.g., change process routes, change safer materials). This is in contrast to the circumstances, where tools are expected to reinforce the inherent safety of equipment. The objective of this research is to identify design mechanism that can help trigger design thinking for implementation of inherent safety in the chemical process industry. To identify such a design mechanism, 526 cases were collected, and knowledge of the mechanism was extracted from design changes and presented in this research paper. The mechanisms were classified according to equipment and inherent safety keywords. The significant design mechanisms from the overall summation were listed (turbulence, change heat transfer fluid, continuous removal, large surface area, corrosion resistance, seamless joint, thin film, dividing wall, on demand, and double wall).

Hazardous chemicals often cause catastrophic accidents, and accidents often result from intricate interactions among various causes. Due to the varying risk factors in different areas of chemical enterprises, to achieve more precise prevention, a more detailed study of the accident risk factors in each area is necessary. Therefore, this study focuses on analyzing critical accident causes and their interrelationships in different functional areas of chemical enterprises to enhance process safety by using a complex network model. Based on 90 accident information, complex network models are constructed for hazardous chemical warehouse areas (HCWAs), tank farm areas (TFAs), and production areas (PAs). Subsequently, a topological analysis of the complex network models is conducted. Based on the PageRank algorithm, 13 critical nodes are identified for HCWAs, while 14 for TFAs and 13 for PAs. Node degree analysis with confidence quantifies mutual influences, forming critical accident causal links for each area. The research results offer decision support for precise accident risk control, aiding in reducing future accidents and improving process system safety in chemical enterprises.

Understanding the degradation behaviour of organic photovoltaic (OPV) devices is an essential part to improve their stability prior to massive production. Accelerated aging can help to assess their stability and study the underlying degradation mechanisms of OPVs. Most studies focus on individual layers or a full device, and little is known about the role a pre-aged layer stack plays in the performance of a device. Herein, we report the investigation of the effects of pre-aging of multiple layers on the performance of OPVs. Instead of aging a single layer or an entire stack (sequential layers: ITO/PEDOT:PSS/MoOx/F-BsubPc/C₆₀/BCP/Ag), our process involved aging the intermediate layer stack for 24 h after depositing a specific layer before continuing with the subsequent depositions to fully fabricate/manufacture OPVs. Aging was conducted under four controlled conditions considering parameters including moisture, gas type, and temperature in the absence of light according to the International Summit on Organic Photovoltaic Stability (ISOS) protocols. Short of PEDOT:PSS we found that multiple layers, being subjected to the parameters, resulted in a decline in OPV device performance after being fully manufactured. Device performance is evaluated based on short-circuit current density (J_sc), power conversion efficiency (PCE), and open-circuit voltage (V_oc). Our analysis provides insight into the degradation mechanisms of layered/planar OPV structures and offers strategic guidance for optimizing fabrication processes, particularly during the layer deposition transitions. We recommend that during OPV vacuum deposited fabrication, intermediate layers should be protected from moisture, O₂, high temperature, and even inert gases, preferably in a low-vacuum environment.

MIL-101-Cr-X (X = OH⁻, F⁻) has been reported to be the most suitable material so far for adsorptive removal of inhalation anaesthetic agents (IAA) sevoflurane and desflurane at the working conditions in hospital operation rooms. To further enhance its affinity and uptake capacity towards IAA, several structural modifications were proposed, and their isotherms were predicted using our molecular simulation approach adopted in our previous publication for the case of the pristine MIL-101-Cr (X = F⁻, OH⁻) structure. The proposed modifications include (1) grafting the metal-cluster site with coordinated NH₃ ligands to produce MIL-101-Cr@NH₃ (X = F⁻, OH⁻), (2) anion exchange of the fluorine atom bonded to chromium with chlorine to synthesize MIL-101-Cr (X = Cl⁻), and (3) functionalization of the benzene rings of the ligand linkers in the MOFs with amino- and nitro- groups in order to form NH₂-MIL-101-Cr (X = Cl⁻) and NO₂-MIL-101-Cr (X = Cl), respectively. Simulated adsorption isotherms of IAA on these modifications were verified by the experimental results using the standard volumetric technique and they clearly demonstrated that MIL-101-Cr@NH₃ (X = F⁻, OH⁻) possesses the highest equilibrium capacity for IAA. This observation can be attributed to the electron-transfer contribution of the coordinated ammonium molecules to the unsaturated coordinated sites of the MOF while doing away with steric hindrance inside the pore cages. The new compound can significantly enhance the economy of adsorptive removal of IAA from vented gas mixtures.

A significant and sustainable feedstock for many value added products is levulinic acid, which is basically a short-chain fatty acid. The current study aims to comprehend how multiple factors affect the hydrothermal reactions that convert glucose to levulinic acid. Glucose can be readily obtained from lignocellulosic biomass and hence it is selected in the work as representative sustainable source. The effect of various operating parameters, including time (0–180 min), temperature (140–180°C), nitrogen pressure (0–25 bar), glucose concentration (3%–10%), agitation speed (100–300 RPM), and acid concentration (2%–6%); use of different salts (NaCl, AlCl₃ 6H₂O, FeCl₃); and different acids (HCl, H₃PO₄, H₂SO₄) on the reaction progress has been studied in a batch autoclave reactor. It was elucidated that pressure (only nitrogen purge was essential for reaction progress) or salt content changes did not affect sugar conversion significantly. The process was seriously influenced by the presence of acids, mostly in the form of homogeneous catalysts, and the most significant results were obtained for H₂SO₄. The highest levulinic acid yield (39.7 g/g) at 90 min, with nearly complete sugar conversion, was obtained under the ideal conditions of 160°C, 5% sugar loading, and 5% H₂SO₄ concentration. The current study indicates that the two primary operating parameters in this conversion process are temperature and time, with higher temperature and lower sugar concentration showing a rising tendency in sugar conversion. Overall, the study establishes a sustainable process for levulinic acid synthesis.

This work develops a fuzzy averaging level controller (ALC) to mitigate flow variability while avoiding high and low level alarm limit breaches. Comparison with proportional (P) and proportional integral (PI) level controllers and their non-linear variants demonstrates the fuzzy controller to be highly effective in mitigating flow transients for low and moderate size flow disturbances. The performance is comparable for large disturbances. Application of the developed fuzzy ALC to a ternary benzene-toluene-xylene direct split separation scheme as well as the separation section of a conventional cumene process demonstrates significantly superior product quality control due to flow transient variability mitigation. The product quality control variability is reduced by up to 1.5 times. The developed fuzzy ALC is therefore suitable for plant-wide control applications.