Analysis of process variables via CFD to evaluate the performance of a FCC riser

Feedstock conversion and yield products are studied through a 3D model simulating the main reactor of the fluid catalytic cracking (FCC) process. Computational fluid dynamic (CFD) is used with Eulerian-Eulerian approach to predict the fluid catalytic cracking behavior. The model considers 12 lumps with catalyst deactivation by coke and poisoning by alkaline nitrides and polycyclic aromatic adsorption to estimate the kinetic behavior which, starting from a given feedstock, produces several cracking products. Different feedstock compositions are considered. The model is compared with sampling data at industrial operation conditions. The simulation model is able to represent accurately the products behavior for the different operating conditions considered. All the conditions considered were solved using a solver ANSYS CFX 14.0. The different operation process variables and hydrodynamic effects of the industrial riser of a fluid catalytic cracking (FCC) are evaluated. Predictions from the model are shown and comparison with experimental conversion and yields products are presented; recommendations are drawn to establish the conditions to obtain higher product yields in the industrial process

Complex reactions in an FCC riser reactor

Computational fluid-dynamic (CFD) is a useful tool to understand the performance and help the design of fluidised catalytic process (FCC) riser. In addition, to characterise the hydrodinamic effects on selectivity and conversion, the cracking kinetics need to be coupled with the hydrodynamics. Experiments are highly desired but they are costly and time consuming, especially, for process equipment at the industrial scale; conversely, computer simulations are usually inexpensive and rapid to conduct. Neverheless, modelling the catalytic cracking of heavy oils is not an easy task, since it involves a very large number of components and reactions. The lumping kinetic approach is often implemented in CFD calculations to simulate the FCC process, however, this approach presents limitations especially in relation to an accurate kinetic description of each lump. This work studies the influence of the kinetics of the reactions on the simulation of an FCC industrial riser. The study aims to give details on the yields of cracking products when coupled with the FCC fluid dynamics; hence, the results obtained are compared with experimental kinetic data from the literature. Our preliminary results show that the technique appropriately describe the experiments and it can be used as an powerful method to implement the kinetics of any complex petroleum reaction mixture in CFD

Evaluation of cyclone geometry and its influence on performance parameters by computational fluid dynamics (CFD)

Cyclone models have been used without relevant modifications for more than a century. Most of the attention has been focused on finding new methods to improve performance parameters. Recently, some studies were conducted to improve equipment performance by evaluating geometric effects on projects. In this work, the effect of cyclone geometry was studied through the creation of a symmetrical inlet and a volute scroll outlet section in an experimental cyclone and comparison to an ordinary single tangential inlet. The study was performed for gas-solid flow, based on an experimental study available in the literature, where a conventional cyclone model was used. Numerical experiments were performed by using CFX 5.7.1. The axial and tangential velocity components were evaluated using RSM and LES turbulence models. Results showed that these new designs can improve the cyclone performance parameters significantly and very interesting details were found on cyclone fluid dynamics properties using RSM and LES.839

A proposal for a new clinical classification of chronic pancreatitis

<p>Abstract</p> <p>Background</p> <p>The clinical course of chronic pancreatitis is still unpredictable, which relates to the lack of the availability of a clinical classification. Therefore, patient populations cannot be compared, the course and the outcome of the disease remain undetermined in the individual patient, and treatment is not standardized.</p> <p>Aim</p> <p>To establish a clinical classification for chronic pancreatitis which is user friendly, transparent, relevant, prognosis- as well as treatment-related and offers a frame for future disease evaluation.</p> <p>Methods</p> <p>Diagnostic requirements will include one clinical criterion, in combination with well defined imaging or functional abnormalities.</p> <p>Results</p> <p>A classification system consisting of three stages (A, B and C) is presented, which fulfils the above-mentioned criteria. Clinical criteria are: pain, recurrent attacks of pancreatitis, complications of chronic pancreatitis (e.g. bile duct stenosis), steatorrhea, and diabetes mellitus. Imaging criteria consist of ductal or parenchymal changes observed by ultrasonography, ERCP, CT, MRI, and/or endosonography.</p> <p>Conclusion</p> <p>A new classification of chronic pancreatitis, based on combination of clinical signs, morphology and function, is presented. It is easy to handle and an instrument to study and to compare the natural course, the prognosis and treatment of patients with chronic pancreatitis.</p

Prognostic role of chromosome 9P deletion in patients with clear cell renal cell carcinoma

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The double-mode nature of the HADS star GSC 00144-03031 and the Petersen diagram of the class

The double--mode pulsation of GSC 00144-03031 has been detected when searching for COROT targets. A very large dataset composed of 4722 photometric measurements was collected at six observatories in Europe and America. There is no hint of the excitation of additional modes (down to 0.6 mmag) and therefore GSC 00144-03031 seems to be a pure double--mode pulsator, with a very short fundamental radial mode (P=84 min). From Stromgren photometry and evolutionary tracks it appears to be a Pop. I star with M=1.75 solar masses, located in the middle of the instability strip, close to the Zero--Age Main Sequence. We also discovered other new double--mode pulsators in the databases of large--scale projects: OGLE BW2_V142, OGLE BW1_V207, ASAS3 094303-1707.3, ASAS3 000116-6037.0, NSVS 3234596 and NSVS 3324715. An observational Petersen diagram is presented and explained by means of new models. A common sequence connecting Pop. I stars from the shortest to the longest periods is proposed and the spreads in the period ratios are ascribed to different metallicities (at the shortest periods) and to different masses (at the longest ones). The paper is based on data collected at S. Pedro Martir and Sierra Nevada Observatories and on the contributions from several amateur astronomers.Comment: 9 pages, 5 pages, accepted for publication in Astronomy and Astrophysic

Pancreatic cancerrelated cachexia: influence on metabolism and correlation to weight loss and pulmonary function

<p>Abstract</p> <p>Background</p> <p>Dramatic weight loss is an often underestimated symptom in pancreatic cancer patients. Cachexia- defined as an unintended loss of stable weight exceeding 10% – is present in up to 80% of patients with cancer of the upper gastrointestinal tract, and has a significant influence on survival. The aim of the study was to show the multiple systemic effects of cachexia in pancreatic cancer patients, in terms of resection rate, effects on pulmonary function, amount of fat and muscle tissue, as well as changes in laboratory parameters.</p> <p>Methods</p> <p>In patients with pancreatic cancer, clinical appearance was documented, including the amount of weight loss. Laboratory parameters and lung-function tests were evaluated, and the thickness of muscle and fat tissue was measured with computed tomography scans. Statistical analysis, including multivariate analysis, was performed using SPSS software. Survival curves were calculated using Kaplan-Meier analysis and the log-rank test. To test for significant differences between the examined groups we used Student's t-test and the Mann-Whitney U test. Significance was defined as p < 0.05.</p> <p>Results</p> <p>Of 198 patients with a ductal adenocarcinoma of the pancreas, 70% were suffering from weight loss when they presented for operation, and in 40% weight loss exceeded 10% of the stable weight. In patients with cachexia, metastases were diagnosed significantly more often (47% vs. 24%, P < 0.001), leading to a significantly reduced resection rate in these patients. Patients with cachexia had significantly reduced fat tissue amounts. Hence, dramatic weight loss in a patient with pancreatic cancer may be a hint of a more progressed or more aggressive tumour.</p> <p>Conclusion</p> <p>Pancreatic cancer patients with cachexia had a higher rate of more progressed tumour stages and a worse nutritional status. Furthermore, patients with cachexia had an impaired lung function and a reduction in fat tissue. Patients with pancreatic cancer and cachexia had significantly reduced survival. If weight loss exceeded 5% there was a significantly reduced resection rate to detect, but the changes were significantly more substantial if weight loss was 10% or more. We propose that a weight loss of 10% be defined as significant in pancreatic cancer.</p

Chromophobe renal cell cancer - review of the literature and potential methods of treating metastatic disease

Chromophobe renal cell carcinoma (ChRCC) is a subtype of renal cell carcinoma (RCC). ChRCC is diagnosed mainly in 6th decade of life. An incidence of ChRCC is similar in both men and woman. Eighty six percent of ChRCCs cases are diagnosed in stage 1 or 2. Prognosis of ChRCC is better than in other types of RCC. Five- and 10-year disease free survival (DFS) for ChRCC was 83.9% and 77.9%, respectively. Expression of immunohistological markers: cytokeratins (CK), vimentin, epithelial membrane antigen (EMA), CD10 could be potentially helpful in diagnosis of different subtypes of RCC. From all conventional RCC, CD 117 was detected (overexpression) in membrane of cells ChRCC