Analyzing Burner Performance and Combustion Phenomenon in an Olefin Plant's Industrial Furnace: A CFD Study.

This work presents a comprehensive study of the combustion performance of an industrial furnace in an olefin plant using computational fluid dynamics (CFD) simulations. The focus was on analyzing the heat release pattern of bottom burners to optimize the furnace efficiency in steam-cracking processes. The study developed an accurate computational fluid dynamics (CFD) model for predicting combustion behavior in a cracking furnace. The computational model was validated by comparing the simulation results with industrial data and was used to investigate the impact of burner clogging and the importance of small holes in the body of burners in the furnace. The results also provided insights into the influence of excess air, temperature distribution, fluid behavior, composition of combustion products, and thermal efficiency of the furnace. The presented results contributed to a better understanding of parameters controlling combustion performance in steam-cracking furnaces.

Study of the kinetic, equilibrium, and thermodynamic aspects of the removal and recovery of divalent lead heavy metal ions from industrial wastewaters contaminated by vesavin-enriched XAD-11600 amberlite resin.

In this study, we developed a unique adsorbent known as extractant-impregnated resin (EIR) by surface impregnation of XAD-11600 amberlite resin with the Vesavin ligand. This resin demonstrated exceptional selectivity for the absorption of lead (Pb2+) ions from aqueous solutions. The ability of EIR to remove lead from polluted water was studied as a function of experimental parameters, including the kinetics, equilibrium, and thermodynamics of the adsorption process. The experimental results provided the basis for the fitting of equilibrium adsorption isotherms with the Langmuir model, and the maximum adsorption capacity of EIR for Pb(II) ions was determined to be approximately 1662 mg/g. Kinetic and thermodynamic studies were also conducted to gain insight into the behavior of the adsorption process. It was found that the rate of penetration of lead ions into the particle was the primary factor controlling the absorption process of lead on the surface of the porous adsorbent. Additionally, the studies demonstrated that the EIR can be utilized for multiple absorption and desorption cycles.

Application of Green Polymeric Nanocomposites for Enhanced Oil Recovery by Spontaneous Imbibition from Carbonate Reservoirs.

This study experimentally investigates the effect of green polymeric nanoparticles on the interfacial tension (IFT) and wettability of carbonate reservoirs to effectively change the enhanced oil recovery (EOR) parameters. This experimental study compares the performance of xanthan/magnetite/SiO2 nanocomposites (NC) and several green materials, i.e., eucalyptus plant nanocomposites (ENC) and walnut shell ones (WNC) on the oil recovery with performing series of spontaneous imbibition tests. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and BET (Brunauer, Emmett, and Teller) surface analysis tests are also applied to monitor the morphology and crystalline structure of NC, ENC, and WNC. Then, the IFT and contact angle (CA) were measured in the presence of these materials under various reservoir conditions and solvent salinities. It was found that both ENC and WNC nanocomposites decreased CA and IFT, but ENC performed better than WNC under different salinities, namely, seawater (SW), double diluted salted (2 SW), ten times diluted seawater (10 SW), formation water (FW), and distilled water (DIW), which were applied at 70 °C, 2000 psi, and 0.05 wt.% nanocomposites concentration. Based on better results, ENC nanofluid at salinity concentrations of 10 SW and 2 SW ENC were selected for the EOR of carbonate rocks under reservoir conditions. The contact angles of ENC nanocomposites at the salinities of 2 SW and 10 SW were 49 and 43.4°, respectively. Zeta potential values were -44.39 and -46.58 for 2 SW and 10 SW ENC nanofluids, which is evidence of the high stability of ENC nanocomposites. The imbibition results at 70 °C and 2000 psi with 0.05 wt.% ENC at 10 SW and 2 SW led to incremental oil recoveries of 64.13% and 60.12%, respectively, compared to NC, which was 46.16%.

Totally ultrasound-guided minimally invasive percutaneous nephrolithotomy in children: Is it safe?

OBJECTIVE: The objective of the study was to assess the outcome and feasibility of ultrasonography (US)-guided minimally invasive percutaneous nephrolithotomy (mini-PCNL) in children. MATERIALS AND METHODS: Twenty-five children with upper urinary tract stones who had undergone US-guided mini-PCNL from June 2017 to June 2020 were enrolled in this study. Patients' demographic information and post-treatment results were retrospectively gathered and analysed. Pyelocaliceal system was punctured in prone position using US guidance, and the tract was dilated using single-shot dilation technique. All steps of renal access were done using only US. Mini-PCNL in all cases was done by using 15 Fr rigid nephroscope. Stones were fragmented with a pneumatic lithotripter and evacuated. RESULTS: The patients' mean age was 6.30 ± 3.25 years (range: 1.5-15). The mean stone size was 16.04 ± 3.93 mm (range: 10-30). The mean access time to the stone was 1.50 ± 0.62 min (range: 1-4). The mean operation time was 94.66 ± 3.05 min (range: 90-100 min). The final stone-free rate was 96%. Post-operation fever occurred in 4 (16%) patients who were treated successfully with an antibiotic. No major complications occurred. CONCLUSIONS: We recommend US-guided mini-PCNL as a harmless alternative treatment option, in children with renal calculi due to its excellent outcomes and little complications.

Outcome of Transperitoneal Laparoscopic Ureterolithotomy (TPLU) for proximal ureteral stone > 15 mm: Our experience with 60 cases.

PURPOSE: We aim to review our experience of transperitoneal laparoscopic ureterolithotomy (TPLU) for proximal ureteric stone more than 15 mm. PATIENTS AND METHODS: Between June 2017 to December 2020, sixty patients with a history of unsuccessful Extracorporeal shock wave lithotripsy (ESWL) and/or failed ureteroscopy for impacted ureteral calculi more than 15 mm who accepted TPLU were enrolled in our study. The patients' demographic information and post-treatment results were gathered and analyzed, retrospectively. RESULTS: The patients' mean age was 46.25 ± 12.56 years. The mean size of the stone was 20.11 ± 4.76 mm. 37 (61.7%) patients had severe hydronephrosis (HDN) and 46 (76.7%) stones were radio-opaque. Almost all of the patients underwent TPLU by a single urologist. The mean operation time was 72.86 ± 6.07 minutes without intraoperative complication (only 3 stones had upward migration to the pyelocaliceal system). The main operative blood loss was 88.86 ml. The average length of stay in the hospital was 45.8 ± 8.11 hours. The stone free rate (SFR) at discharge was 57 (95%). The overall complication rate was 27 (45%). Regarding early complications, fever was found in 8 (13.3%) patients, and 3 patients (5%) had paralytic ileus. The rate of urine leak was 8.3%, and 8 (13.3%) patients required blood transfusions. In multivariate analysis, the multiple stones, bigger stone in size, incomplete SFR, longer duration of hospital admission, and severe HDN were associated with a high early complication rate (p = 0.05, 0.04, < 001, 0.03, and 0.01, respectively). CONCLUSIONS: TPLU is a harmless option for managing proximal ureteric stone as a primary procedure or salvage procedure with good outcomes and acceptable complication rates.

Robust and universal predictive models for frictional pressure drop during two-phase flow in smooth helically coiled tube heat exchangers.

There is a lack of well-verified models in the literature for the prediction of the frictional pressure drop (FPD) in the helically coiled tubes at different conditions/orientations. In this study, the robust and universal models for estimating two-phase FPD in smooth coiled tubes with different orientations were developed using several intelligent approaches. For this reason, a databank comprising 1267 experimental data samples was collected from 12 independent studies, which covers a broad range of fluids, tube diameters, coil diameters, coil axis inclinations, mass fluxes, saturation temperatures, and vapor qualities. The earlier models for straight and coiled tubes were examined using the collected database, which showed absolute average relative error (AARE) higher than 21%. The most relevant dimensionless groups were used as models' inputs, and the neural network approach of multilayer perceptron and radial basis functions (RBF) were developed based on the homogenous equilibrium method. Although both intelligent models exhibited excellent accuracy, the RBF model predicted the best results with AARE 4.73% for the testing process. In addition, an explicit FPD model was developed by the genetic programming (GP), which showed the AARE of 14.97% for all data points. Capabilities of the proposed models under different conditions were described and, the sensitivity analyses were performed.

Intelligent modeling and experimental study on methylene blue adsorption by sodium alginate-kaolin beads.

As tighter regulations on color in discharges to water bodies are more widely implemented worldwide, the demand for reliable inexpensive technologies for dye removal grows. In this study, the removal of the basic dye, methylene blue, by adsorption onto low-cost sodium alginate-kaolin beads was investigated to determine the effect of operating parameters (initial dye concentration, contact time, pH, adsorbent dosage, temperature, agitation speed) on dye removal efficiency. The composite beads and individual components were characterized by a number of analytical techniques. Three models were developed to describe the adsorption as a function of the operating parameters using regression analysis, and two powerful intelligent modeling techniques, genetic programming and artificial neural network (ANN). The ANN model is best in predicting dye removal efficiency with R2 = 0.97 and RMSE = 3.59. The developed model can be used as a useful tool to optimize treatment processes using the promising adsorbent, to eliminate basic dyes from aqueous solutions. Adsorption followed a pseudo-second order kinetics and was best described by the Freundlich isotherm. Encapsulating the kaolin powder in sodium alginate resulted in removal efficiency of 99.56% and a maximum adsorption capacity of 188.7 mg.g-1, a more than fourfold increase over kaolin alone.

Adsorption of Amido Black 10B from aqueous solution using polyaniline/SiO2 nanocomposite: Experimental investigation and artificial neural network modeling.

The present work focused on the performance of Polyaniline/SiO2 nanocomposite for removing Amido Black 10B dye from aqueous solution. The effect of different variables, such as adsorption time, the mass of adsorbent, solution pH and initial dye concentration was studied and also was optimized by an Artificial Neural Network (ANN) method. Lagergren, pseudo-second order, Intra-particle Diffusion, Elovich and Boyd models were tested to track the kinetics of the adsorption process. The experimental data were fitted to different two-parameter, and three-parameter isotherm models, namely, Langmuir, Freundlich, Temkin, D-R, Hill, Sips and Redlich-Peterson models, and their validity was examined. The results showed that the dye adsorption process was well described by Redlich-Peterson isotherm model. Thermodynamic studies revealed that the adsorption of Amido Black 10B onto Polyaniline/SiO2 nanocomposite was endothermic. The comparison of the adsorption efficiencies obtained by the ANN model and the experimental data evidenced that the ANN model could estimate the behavior of the Amido Black 10B dye adsorption process under various conditions.

Kinetic, equilibrium and thermodynamic studies on sorption of uranium and thorium from aqueous solutions by a selective impregnated resin containing carminic acid.

In this work, the removal of uranium and thorium ions from aqueous solutions was studied by solid-liquid extraction using an advantageous extractant-impregnated resin (EIR) prepared by loading carminic acid (CA) onto Amberlite XAD-16 resin beads. Batch sorption experiments using CA/XAD-16 beads for the removal of U(VI) and Th(IV) ions were carried out as a function of several parameters, like equilibration time, metal ion concentration, etc. The equilibrium data obtained from the sorption experiments were adjusted to the Langmuir isotherm model and the calculated maximum sorption capacities in terms of monolayer sorption were in agreement with those obtained from the experiments. The experimental data on the sorption behavior of both metal ions onto the EIR beads fitted well in both Bangham and intra-particle diffusion kinetic models, indicating that the intra-particle diffusion is the rate-controlling step. The thermodynamic studies at different temperatures revealed the feasibility and the spontaneous nature of the sorption process for both uranium and thorium ions.

Compare the effects of different visfatin concentration on cardiovascular risk factors, adiponectin and insulin resistance in patients with T2DM.

AIM: The discovery of new adipokine, visfatin can significantly enhance our knowledge of insulin resistance and diabetes mellitus. We explored the relation of visfatin concentrations to cardiovascular risk factors, adiponectin and insulin resistance criteria in patients with type 2 diabetes mellitus (T2DM). MATERIALS AND METHODS: Fifty-eight patients with T2DM were recruited from the out patients clinic of Shariati Hospital. Laboratory and anthropometric measurements include FBG, OGTT, HbA1c, fasting serum visfatin, insulin and adiponectin, HOMA-IR and hsCRP, weight, height, BMI and WHR were performed in all participants. All of the statistical data were analyzed using the SPSS15 software. RESULTS: The log(10)-transformed (log) plasma visfatin concentration was in significant positive correlation with age (r=0.286, p=0.033). Patients were divided in two groups by median log visfatin (0.85 ng/mL): group I had low values and group II had high values. In group I the log visfatin was in significant positive correlation with age (r=0.436, p=0.018) and in group II log visfatin was in significant negative correlation with FPG and HbA1c (r>0.4, p<0.05). CONCLUSION: In conclusion high circulating levels of visfatin could be in healthy relations with cardiovascular risk factors, insulin resistance status and adiponectin in diabetic patients.