Process simulation and assessment of a back-up condensate stabilization unit

YesA simulation was conducted using Aspen HYSYS® software for an industrial scale condensate stabilization unit and the results of the product composition from the simulation were compared with the plant data. The results were also compared to the results obtained using PRO/II software. The results show that the simulation is in good agreement with the plant data, especially for medium range hydrocarbons. For hydrocarbons lighter than C5, the simulation results over predict the plant data while for hydrocarbons heavier than C9 this trend is reversed. The influences of steam temperature and pressure, as well as feed conditions (flow rate, temperature and pressure) for the product specification (RVP and sulphur content) were also investigated. It was reported that the operating conditions gave rise to the production of off-specification condensate and it was also found that the unit could be utilized within 40–110% of its normal throughput without altering equipment sizing and by the operating parameters

Comparison of complications of spinal and general anesthasia in percutaneous kidney stone removal

While the complications of spinal anesthesia are much less than general anesthesia, percutaneous nephrolithotomy (PCNL) is still performed under general anesthesia in most centers. Therefore, in this study spinal anesthesia is compared with general anesthesia in patients undergoing PCNL. This research was a double-blind clinical trial study which was conducted on 130 patients with inclusion criteria. Patients were nonrandomly assigned into two general anesthesia (n=65) and spinal anesthesia (n=65) groups and underwent PCNL surgery.In group A, patients were given intravenously midazolam (2 mg), fentanyl (100 μg), atracurium (0.5 mg/kg), propofol (2 mg/kg) and morphine (10 mg) and then were incubated. In group B, Marcaine 0.5% (15 mg) was injected into the L3-L4 or L4-L5 lumbar spinal space in a sitting position. Patient’s blood pressure was measured and recorded at various times and in recovery as well as in the surgery room. Intra-operative bleeding, pain in the surgery area, nausea and vomiting, shortness of breath and sore throat were recorded for the two groups in the ward and during hospitalization.Changes of blood pressure were the same in both groups. In the general anesthesia group, intra-operative bleeding, pain at the site of the surgery, nausea and vomiting, shortness of breath and sore throat and duration of hospitalization were significantly higher. Changes in other tests were equal in both groups. Spinal anesthesia might be a safer method than general anesthesia for PCNL surgery.Keywords: Complication, Spinal Anesthesia, General Anesthesia, Kidney Stone Removal, Percutaneou

Prevalence and risk factors of complication of endotracheal extubation in teaching hospitals affiliated with Jahrom University of medical science

Endotracheal intubation is to maintain a safe open airway to prevent pulmonary aspiration by administrating general anesthesia. Endotracheal tube, as a foreign body, can stimulate the patients’ airway during the emergence from general anesthesia and cause various reactions and complications immediately or within a multi-day delay.The present study intended to determine the prevalence and associated risk factors of the complications of endotracheal extubation (removal of endotracheal tube / ETT) within 24 hrs. since the surgery. To this end, a descriptive research was conducted on 200 adult candidates for elective and emergency surgery of endotracheal intubation by administrating general anesthesia. Data about the intended associated risk factors and complications were respectively collected in operating room (OR) and within 24 hrs. since surgery and were recorded in the questionnaire. The results indicated that the prevalent complications were sore throat (%21), cough (%12.5) and hoarseness (%15.5). There was not any case of dysphagia and bloody sputum (blood-streaked expectorant). Also, there was a significant relationship between sore throat and the type of surgery (P˂0.001). On the other hand, there was not any statistically significant relationship between sore throat and other associated risk factors (sex, age, weight, type of surgery and size of endotracheal tube). Likewise, not any significant relationship was observed between cough, hoarseness and the intended risk factors. To conclude, the present study found that the type of surgery has a significant effect on the incidence of sore throat within 24 hrs. since the surgical operation; thus, raising awareness of these risk factors and taking proper actions, particularly during intubation, can reduce the incidence of complications, in particular sore throat, and improve patients’ satisfaction.Keywords: General Anesthesia; Intubation; Complication

Simulation and Optimization of a Condensate Stabilization Process

yesA simulation was conducted using Aspen HYSYS® software for an industrial scale condensate stabilization unit and the results of the product composition from the simulation were compared with the plant data. The results were also compared to the results obtained using PRO/II software. It was found that the simulation is closely matched with the plant data and in particular for medium range hydrocarbons. The effects of four process conditions, i.e. feed flow rate, temperature, pressure and reboiler temperature on the product Reid Vapour Pressure (RVP) and sulphur content were also studied. The operating conditions which gave rise to the production of off-specification condensate were found. It was found that at a column pressure of 8.5 barg and reboiler temperature of 180°C, the condensate is successfully stabilised to a RVP of 60.6 kPa (8.78 psia). It is also found that as compared to the other parameters the reboiler temperature is the most influential parameter control the product properties. Among the all sulphur contents in the feed, nP-Mercaptan played a dominant role for the finishing product in terms of sulphur contents.The full text will be available at the end of the publisher's embargo, 12 months after publication

Applications of Biocatalysts for Sustainable Oxidation of Phenolic Pollutants: A Review

YesPhenol and its derivatives are hazardous, teratogenic and mutagenic, and have gained significant attention in recent years due to their high toxicity even at low concentrations. Phenolic compounds appear in petroleum refinery wastewater from several sources, such as the neutralized spent caustic waste streams, the tank water drain, the desalter effluent and the production unit. Therefore, effective treatments of such wastewaters are crucial. Conventional techniques used to treat these wastewaters pose several drawbacks, such as incomplete or low efficient removal of phenols. Recently, biocatalysts have attracted much attention for the sustainable and effective removal of toxic chemicals like phenols from wastewaters. The advantages of biocatalytic processes over the conventional treatment methods are their ability to operate over a wide range of operating conditions, low consumption of oxidants, simpler process control, and no delays or shock loading effects associated with the start-up/shutdown of the plant. Among different biocatalysts, oxidoreductases (i.e., tyrosinase, laccase and horseradish peroxidase) are known as green catalysts with massive potentialities to sustainably tackle phenolic contaminants of high concerns. Such enzymes mainly catalyze the o-hydroxylation of a broad spectrum of environmentally related contaminants into their corresponding o-diphenols. This review covers the latest advancement regarding the exploitation of these enzymes for sustainable oxidation of phenolic compounds in wastewater, and suggests a way forward

Growth kinetics of nuclei formed from different binders and powders in vertical cylindrical mixing devices

peer-reviewedGranulation is the process of forming large aggregates from fine particles using a high shear mixer. This method is used in several industries from pharmaceuticals to chemical and fertilizer production. This research will study the effect of four process variables: speed of mixer rotation in the range 100–200 rpm, powder bed mass (25–40 g), mass of the initial nucleus (0.6–2 g), and binder viscosity (water, carboxymethyl cellulose (CMC) solutions with concentrations in the range 0.5–20 g/L) on single nuclei growth kinetics in low mixing devices. The powders under study were: lactose, tea, sugar, starch, and limestone. The results show the initial size of nuclei, the initial mass of the powder bed and binder viscosity and speed of rotation all influence the rate of nuclei growth. Analysis of the stokes deformation number of the nuclei show that growth rate of the nuclei decreases as the deformation number increases whilst the percentage gain in mass of the nuclei increases with increasing deformation number. The binder viscosity was shown to have the biggest influence of the growth rate of the nuclei. Results show that difference in powder density also has an effect on the growth kinetics of nuclei. The initial position of nuclei was also shown to influence the nuclei growth rate; the closer the starting position of the nuclei to the wall of the vessel the slower the growth rate

Carbon and glass hierarchical fibers : influence of carbon nanotubes on tensile, flexural and impact properties of short fiber reinforced composites

Dense carbon nanotubes (CNTs) were grown uniformly on the surface of carbon fibers and glass fibers to create hierarchical fibers by use of floating catalyst chemical vapor deposition. Morphologies of the CNTs were investigated using scanning electronic microscope (SEM) and transmission electron microscope (TEM). Larger diameter dimension and distinct growing mechanism of nanotubes on glass fiber were revealed. Short carbon and glass fiber reinforced polypropylene composites were fabricated using the hierarchical fibers and compared with composites made using neat fibers. Tensile, flexural and impact properties of the composites were measured, which showed evident enhancement in all mechanical properties compared to neat short fiber composites. SEM micrographs of composite fracture surface demonstrated improved adhesion between CNT-coated fiber and the matrix. The enhanced mechanical properties of short fiber composites was attributed to the synergistic effects of CNTs in improving fiber–matrix interfacial properties as well as the CNTs acting as supplemental reinforcement in short fiber-composites