Integration of safety instrumented system with automated HAZOP analysis: An application for continuous biodiesel production

Integration of a human-machine interface (HMI) with hazard and operability (HAZOP) analysis is proposed in this work. This concept can potentially lead to the identification of some unexpected deviations, and radically decreases the time necessary for hazard identification. A continuous biodiesel production was simulated. This can be divided into two cases, covering both conventional and reactive distillation. Soybean oil (trioleic, trilinoleic and tripalmitic) at 1000 kg/h as raw material is converted to 99 wt% pure biodiesel. The HMI was designed to improve these processes by combining automatic HAZOP analysis. With this approach, users can receive sufficient information from the simulation to analyze the optimum operation and safety. Severity levels are also provided to classify the actions in the process. Severity levels 1 and 2 are concerned with operating conditions, which are 58-64 °C, and 50-150 kPa. If the analysis shows severity level 3, the safety instrumented system (SIS) will automatically manage the operation in order to reduce/restrain the amount of damage at this level. This proposed system could minimize the damage and also improve the overall quality of the process.     

Effects of protein properties on ultrafiltration membrane fouling performance in water treatment

Protein-like substances always induce severe ultrafiltration (UF) membrane fouling. To systematically understand the effect of proteins, regenerated cellulose UF membrane (commonly used for protein separation) performance was investigated in the presence of bovine serum albumin (BSA) under various water conditions. Results showed that although trypsin enhanced the membrane flux via proteolysis, catalysis took a long time. Membrane fouling was alleviated at high solution pH and low water temperature owing to the strong electrostatic repulsion force among BSA molecules. Both Na⁺ and Ca²⁺ could increase membrane flux. However, Ca²⁺ played a bridging role between adjacent BSA molecules, whereas membrane fouling was alleviated via a hydration repulsion force with Na⁺. The order of influence on membrane fouling was as follows: Ca²⁺ concentration > Na⁺ concentration > pH > temperature > trypsin concentration. Furthermore, a polyvinylidene fluoride UF membrane experiment showed that Ca²⁺ could reduce the fouling induced by BSA. Thus, the differences in UF membrane performance will have application potential for alleviating UF membrane fouling induced by proteins during water treatment.     

Fabrication of PVDF nanofibrous hydrophobic composite membranes reinforced with fabric substrates via electrospinning for membrane distillation desalination

To improve the mechanical properties of the electrospun nanofibrous membrane, the nonwoven fabrics and spacer fabrics were employed as support substrates to fabricate polyvinylidene fluoride(PVDF) nanofibrous composite membranes. The influences of the substrate on membrane morphology, hydrophobicity, pore size and pore size distribution,porosity, mechanical strength and permeability were comprehensive evaluated. The electrospun composite membranes had a three dimension bead-fiber interconnected open structure and a rough membrane surface. The membrane surface presented a multilevel re-entrant structure and all the water contact angles were above 140°. In contrast with the pure PVDF nanofibrous membrane, the stress at break and the elastic modulus of the composite membranes increased by 4.5–16 times and 17.5–37 times, respectively. Since the spacer fabrics had less resistance to mass transfer, the membranes composited with spacer fabrics exhibited greater permeate fluxes compared with the composite membranes with the nonwoven fabrics as substrates.During the membrane distillation test, the highest permeate flux was up to 49.3 kg/m~2/hr at the feed temperature of 80°C. The long-time and repeat operation of membrane distillation desalination indicated the fabricated membrane with a good resistance to scaling and wetting.The results suggested the potential of the electrospun composite membrane for membrane distillation application.     

芳烃石油树脂生产的环境保护

乙烯装置的副产品在综合利用中存在着严重的环境污染问题。中原油田采取了一些措施。用催化剂对生产尾气进行吸收,将有毒的氟化物转化为钙盐用于磷肥生产;将石油树脂聚合液中BF3脱除,防止对大气、水进行污染;用冷却回收工艺对减压蒸馏放空的芳烃气体进行处理。通过上述治理大大改善了企业的环境,有效地防止了环境污染。     

陶瓷膜处理含油乳化废水的技术研究

虽然钢铁企业在钢表面清洁和涂层处理技术上取得了许多技术改进,但复杂的成分给废水处理带来了极大的困难,现有的处理技术受到了挑战。要处理这些成分复杂且分子量小的含油乳化废水需要采用新的过滤和处理技术,本文将机械加工过程中产生的含油乳化废水作为处理和研究的对象,对陶瓷膜处理含油乳化废水作一赘述。     

Biological treatment of fish processing wastewater: A case study from Sfax City (Southeastern Tunisia)

The present work presents a study of the biological treatment of fish processing wastewa at salt concentration of 55 g/L. Wastewater was treated by both continuous stirred-ta reactor(CSTR) and membrane bioreactor(MBR) during 50 and 100 days, respectively. Th biological processes involved salt-tolerant bacteria from natural hypersaline environme at different organic loading rates(OLRs). The phylogenetic analysis of the correspond excised DGGE bands has demonstrated that the taxonomic affiliation of the most domin species includes Halomonadaceae and Flavobacteriaceae families of the Proteobacteria(Gamm proteobacteria class) and the Bacteroidetes phyla, respectively. The results of MBR w better than those of CSTR in the removal of total organic carbon with efficiencies from 97 to 98.6%. Nevertheless, salinity with increasing OLR aggravates fouling that requires m cleaning for a membrane in MBR while leads to deterioration of sludge settleability a effluent quality in CSTR.     

混凝预处理及膜面流速控制对微滤膜污染的影响研究

为研究膜面流速和混凝预处理对微滤过程膜污染的综合影响,用旋流式膜混凝反应器进行了不同流量、入口管径、混凝剂投加量下的除浊试验。结果表明,直接微滤时,高膜面流速加剧了初期膜的孔堵污染,但抑制了滤饼层的累积,适于长期运行;在质量浓度为0~18 mg/L范围内增大聚合氯化铝（PAC）投加量可显著抑制膜过滤阻力的增长;以速度梯度（G）表征絮体状态,由于絮体尺寸和错流的综合作用,投加混凝剂后,G在20~70 s-1范围内,414.64 s-1时微滤膜污染较轻。     

聚乙烯醇精馏残渣组分分析及其环境风险评价

为评估聚乙烯醇生产中精馏残渣组分及其环境污染风险,为此类危险废物的环境管理提供技术支持,采集华东某聚乙烯醇生产企业的精馏残渣,分析其重金属以及有机污染物含量,并评估其环境风险。研究结果表明聚乙烯醇精馏残渣主要来自生产环节中的醋酸乙烯精制工段,残渣中的有机物组分主要为醋酸及其他有机酸类,其中醋酸的相对含量达到63.47%;残渣中的重金属主要包括Zn、Ni和Cr,其含量分别为404 537 mg·kg-1,8 654 mg·kg-1和5 084 mg·kg-1。环境风险评价的结果表明残渣中有机物污染物引起的环境风险在可接受范围内,而重金属污染严重,同时有很高潜在生态风险。精馏残渣中的主要环境污染风险因子为醋酸、Zn和Ni。     

Structure and flow calculation of cake layer on microfiltration membranes

Submerged membrane bioreactors(SMBR) are widely used in wastewater treatment. The permeability of a membrane declines rapidly because of the formation of a cake layer on the membrane surface. In this paper, a multiple staining protocol was conducted to probe the four major foulants in the cake layer formed on a filtration membrane. Fluorescent images of the foulants were obtained using a confocal laser scanning microscope(CLSM). The three dimensional structure of the cake layer was reconstructed, and the internal flow was calculated using computational fluid dynamics(CFD). Simulation results agreed well with the experimental data on the permeability of the cake layer during filtration and showed better accuracy than the calculation by Kozeny–Carman method. β-D-Glucopyranose polysaccharides and proteins are the two main foulants with relatively large volume fractions, while α-D-glucopyranose polysaccharides and nucleic acids have relatively large specific surface areas. The fast growth of β-D-glucopyranose polysaccharides in the volume fraction is mainly responsible for the increase in cake volume fraction and the decrease in permeability. The specific area, or the aggregation/dispersion of foulants, is less important to its permeability compared to its volume fraction.     

沙滤器回洗水薄膜过滤法

介绍了荷兰新近研究成功的适用于处理沙粒过滤器回洗水的XIGA薄膜法,及其参数、工作原理、适用条件和经济效益。