Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Jamshid Behin,Hamid Reza Kavianpour
Petroleum and Coal , 2009,
Abstract: The steady state simulation of an industrial naphtha catalytic reformer was carried out consideringa kinetic model of reforming reactions proposed by Padmavathi and Chaudhuri (1997). Thepressure drop on solid catalyst was included using Ergun equation. The process model was appliedto predict reformate's composition and temperature profiles in the reforming unit ofKermanshah/Iran refinery consists of three fixed bed reactors in series. The mole fraction ofparaffins, naphthenes, and aromatics in effluent of third reactor were determined. The final outletresults were compared with experimental data and a good agreement was shown. The simulationresults with considering pressure drop were in a better agreement with actual operation plant datawhereas no significant difference was observed.
JL Li,KF Wong,GH Zhu Fushun Petroleum Institute,Fushun,China State Key Laboratory for Corrosion,Protection of Metal,Institute of Corrosion,Protection of Metals,The Chinese Academy of Sciences,Shenyang,China Zhejiang University,Hangzhou,China,
J.L. Li
,K.F. Wong and G.H. Zhu Fushun Petroleum Institute,Fushun,China State Key Laboratory for Corrosion and Protection of Metal,Institute of Corrosion and Protection of Metals,The Chinese Academy of Sciences,S

金属学报(英文版) , 1999,
Abstract: This paper integrates the characteristic of structure design and manufacture and maintenance for Chinese flat steel band wound pressure vessel(UCWPV) with the problems existing in current in service high temperature and pressure vessel exposed to hydrogen. In view of economy and safety it is suggested that it be practicable for UCWPV to act as reactors for platreating, hydrogenating, and catforming. UCWPV has not only potential advantages, but also removes shortages present in in-service reactors for hydrogen.
Design Optimization of Stress Relief Grooves in Lever Guide of Pressure Vessel for Food Processing  [PDF]
Yuichi Otsuka, Hamirdin Bin Baron, Yoshiharu Mutoh
Open Journal of Safety Science and Technology (OJSST) , 2012, DOI: 10.4236/ojsst.2012.21001
Abstract: A stress relief groove is introduced in the R area and the stress is analyzed using a finite element method (FEM). Then the relief of the stress concentration in the vicinity of the pressure vessel is measured based on these results. When designing a stress relief groove, the lever must overhang the groove (L > 0). By introducing a stress relief groove to the R area, maximum stress on the lever guide can be reduced by 10%. This enables the reduction of the maximum stress (Mises stress) to be less than the fatigue strength. Furthermore, the location where maximum stress occurs on the lever guide changes in accordance with the clearance between the lever and lever guide. This identified the need to take into account the deviation factor such as design clearance in modeling process.
Optimal Design of Hydraulic System for an Industrial Press Machine for Performance Improvement and Noise Reduction
Jiafeng Yao, Baochun Lu, Chris Zhang, Michio Sadatomi
Open Journal of Mechanical Engineering , DOI: 10.7508/JME-V1-N3-1-16
Abstract: In this paper, we present an optimal design of the hydraulic system for a class of industrial press machines. Such machines are expected to produce a large pressure on a work-piece and they are driven by a hydraulic system. Excessive vibration in the period where the press is changed from pressure holding to pressure relief is a common bottleneck problem with such machines. The vibration is closely related to the hydraulic system that controls a press head’s movement and is subsequently responsible for the property of work-pieces. In the present study, we proposed a novel design of the hydraulic circuit for pressure relief and applied it to a brick press machine and evaluated through simulation by AMESim software, which showed that the design is effective. Finally, the simulation results were validated in practical operation, which showed that, the violent vibration was decreased significantly and the noise level of the new machine is decreased from 80 decibel to 58 decibel.
Monolitni katalizatori i reaktori: osnovne zna ajke, priprava i primjena (Monolith catalysts and reactors: preparation and applications)  [PDF]
Toma?i?, V.
Kemija u Industriji , 2004,
Abstract: Monolithic (honeycomb) catalysts are continuous unitary structures containing many narrow, parallel and usually straight channels (or passages). Catalytically active components are dispersed uniformly over the whole porous ceramic monolith structure (so-called incorporated monolithic catalysts) or are in a layer of porous material that is deposited on the walls of channels in the monolith's structure (washcoated monolithic catalysts). The material of the main monolithic construction is not limited to ceramics but includes metals, as well. Monolithic catalysts are commonly used in gas phase catalytic processes, such as treatment of automotive exhaust gases, selective catalytic reduction of nitrogen oxides, catalytic removal of volatile organic compounds from industrial processes, etc. Monoliths continue to be the preferred support for environmental applications due to their high geometric surface area, different design options, low pressure drop, high temperature durability, mechanical strength, ease of orientation in a reactor and effectiveness as a support for a catalytic washcoat. As known, monolithic catalysts belong to the class of the structured catalysts and/or reactors (in some cases the distinction between "catalyst" and "reactor" has vanished). Structured catalysts can greatly intensify chemical processes, resulting in smaller, safer, cleaner and more energy efficient technologies. Monolith reactors can be considered as multifunctional reactors, in which chemical conversion is advantageously integrated with another unit operation, such as separation, heat exchange, a secondary reaction, etc. Finally, structured catalysts and/or reactors appear to be one of the most significant and promising developments in the field of heterogeneous catalysis and chemical engineering of the recent years. This paper gives a description of the background and perspectives for application and development of monolithic materials. Different methods and techniques used in the preparation of monolithic catalysts are described. Several commercial applications of monolithic catalysts are presented. New applications and the associated technical challenges for the monolithic catalyst and reactors are discussed as well.
Reduction of peak plantar pressure in people with diabetes-related peripheral neuropathy: an evaluation of the DH Pressure Relief Shoe  [cached]
Raspovic Anita,Landorf Karl B,Gazarek Jana,Stark Megan
Journal of Foot and Ankle Research , 2012, DOI: 10.1186/1757-1146-5-25
Abstract: Background Offloading plantar pressure is a key strategy for the prevention or healing of neuropathic plantar ulcers in diabetes. Non-removable walking casts, such as total contact casts, are currently considered the gold-standard for offloading this type of wound. However, alternative methods for offloading that are more cost effective and easier to use are continually being sought. The aim of this study was to evaluate the capacity of the DH Pressure Relief Shoe to offload high pressure areas under the neuropathic foot in diabetes. Methods A within-subjects, repeated measures design was used. Sixteen participants with diabetic peripheral neuropathy were recruited and three footwear conditions were evaluated in a randomised order: a canvas shoe (the control), the participants’ own standard shoe, and the DH Pressure Relief Shoe . The primary outcome was peak plantar pressure, measured using the pedar-X mobile in-shoe system between the three conditions. Results Data analysis was conducted on 14 out of the 16 participants because two participants could not complete data collection. The mean peak pressure values in kPa (±SD) for each condition were: control shoe 315.9 (±140.7), participants’ standard shoe 273.0 (±127.1) and DH Pressure Relief Shoe 155.4 (±89.9). There was a statistically significant difference in peak plantar pressure between the DH Pressure Relief Shoe compared to both the control shoe (p = 0.002) and participants’ standard shoe (p = 0.001). The DH Pressure Relief Shoe decreased plantar pressures by 51% compared to the control shoe and by 43% compared to participants’ standard shoe. Importantly, for a couple of study participants, the DH Pressure Relief Shoe appeared unsuitable for day-to-day wearing. Conclusions The DH Pressure Relief Shoe reduced plantar pressures more than the other two shoe conditions. The DH Pressure Relief Shoe may be a useful alternative to current offloading modalities used in clinical management of diabetic foot ulceration. However, clinical trials are needed to test their effectiveness for ulcer healing and to ensure they are useable and safe for patients in everyday activities.
The Statistical Experimental Design for Chemical Reactors Modeling  [PDF]
Graciela Prieto, Oscar Prieto, Teresa Unzaga, Carlos Gay, Kazunori Takashima, Akira Mizuno
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.714133
Abstract: The Statistical Experimental Design techniques are the most powerful tools for the chemical reactors experimental modeling. Empirical models can be formulated for representing the chemical behavior of reactors with the minimal effort in the necessary number of experimental runs, hence, minimizing the consumption of chemicals and the consumption of time due to the reduction in the number of experimental runs and increasing the certainty of the results. Four types of nonthermal plasma reactors were assayed seeking for the highest efficiency in obtaining hydrogen and ethylene. Three different geometries for AC high voltage driven reactors, and only a single geometry for a DC high voltage pulse driven reactor were studied. According to the fundamental principles of chemical kinetics and considering an analogy among the reaction rate and the applied power to the plasma reactor, the four reactors are modeled following the classical chemical reactors design to understand if the behavior of the nonthermal plasma reactors can be regarded as the chemical reactors following the flow patterns of PFR (Plug Flow Reactor) or CSTR (Continuous Stirred Tank Reactor). Dehydrogenation is a common elimination reaction that takes place in nonthermal plasmas. Owing to this characteristic, a paraffinic heavy oil with an average molecular weight corresponding to C15 was used to study the production of light olefins and hydrogen.
Shade netting: simple design –effective relief  [PDF]
Ingrid Macdonald
Forced Migration Review , 2010,
Abstract: NRC’s simple but innovative shelter design provided relief forthousands of displaced people in Pakistan.
A New Fuel Design for Two Different HW Type Reactors  [PDF]
Daniel O. Brasnarof,Armando C. Marino,Juan E. Bergallo,Luis E. Juanicó
Science and Technology of Nuclear Installations , 2011, DOI: 10.1155/2011/194650
Abstract: A new fuel element (called CARA) designed for two different heavy water reactors (HWRs) is presented. CARA could match fuel requirements of both (one CANDU and one unique Siemens's design) Argentine HW reactors. It keeps the heavier fuel mass density and hydraulic flow restriction in both reactors together with improving both thermomechanic and thermalhydraulic, safety margins of present fuels. In addition, the CARA design could be considered as another design line for the next generation of CANDU fuels intended for higher burnup. 1. Introduction Argentina has two pressurized heavy water reactor (PHWR) nuclear power plants (NPPs) in operation (Atucha I and Embalse) since 1974 and 1984, respectively, operated by the same national utility (N.A.S.A.) and has another one under construction projected to be connected to the grid in 2012 (Atucha II). Although both of them are cooled by pressurized heavy water, designed to be fuelled with natural uranium, and moderated with heavy water, they have strongly different designs. Embalse is a standard CANDU-6 [1, 2], horizontal pressure-tubes typical Canadian reactor. Atucha I and II have a unique Siemens' design: vertical fuel channels inside a pressure vessel reactor [3]. Fuels for Atucha I and II have small dimensional differences for the rod diameter and structural spacer grids. Both nuclear power plants use on-line refuelling, but they differ in the length and number of their fuel elements (FEs). Embalse uses a short FE with a length of 0.5 meter (see Figure 1) [4], and, so, the horizontal 6-meter-long fuel channel is filled with twelve FEs. The vertical channel of Atucha is filled by one FE of 5.3 meters active length (see Figure 2) [3]. Both fuels use 37 fuel rods arranged in a circular cluster array but with different designs of cladding: (1) Atucha has self-supporting rods and one structural rod without fuel, following PWR design [5]; (2) Embalse has collapsible rods, following the well-known CANDU design [4]. Figure 1: CANDU fuel element. Figure 2: Atucha I fuel element. The Atucha’s fuel uses structural rigid spacer grids at intermediate positions like in PWRs [5]. The fuel of Embalse follows the principle of the CANDU series: a cluster of collapsible rods supported on its extremes by two structural plates (end plates). It uses middle-plane appendages welded on cladding to avoid fretting between contiguous rods (spacers) and between rods to pressure-tube wall (bearing pads). Both reactors use 37 fuel rods of similar diameters (1.0% greater than the Embalse one), and, therefore, they have similar
Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates
Nasib Qureshi, Bassam A Annous, Thaddeus C Ezeji, Patrick Karcher, Ian S Maddox
Microbial Cell Factories , 2005, DOI: 10.1186/1475-2859-4-24
Abstract: Biochemical reactors play an important role in the biochemical industry as the rate of reaction, ease, and length of reactor operation affect reactor productivities and hence process economics [1,2]. In order to employ a most appropriate reactor for an industrial operation, reaction rate should be high and the reactor configuration should be simple. Under optimized parameters such as pH, temperature, substrate, and medium components, reaction rate can be increased by increasing cell mass concentration in the reactor. There are two methods commonly used for increasing cell mass concentration inside the reactor; first, use of a permeable membrane to retain cells; and the other, use of immobilized cell technique. Membrane reactors allow passing of liquid, substrate, and product out of the reactor while retaining the cells. In these reactors, high cell concentrations can be achieved [3]. Unfortunately, for some processes such as waste water treatment, these reactors are not preferred due to their high cost and problems with fouling. Other processes where the relatively high cost of these reactors does not allow their use include production of large volume, low cost chemicals such as vinegar or acetic acid.Other types of reactors that offer high reaction rates are immobilized cell reactors [4]. In these reactors, high cell concentrations are achieved by fixing them on various supports. Cells can be immobilized by three different techniques; namely, adsorption, entrapment, and covalent bond formation. Entrapment and covalent bond formation require use of chemicals that add to the cost of production and perhaps restrict further propagation or increase in cell concentration inside the reactor. The third technique is of natural origin as cells "adsorb/and adhere" to the support naturally and firmly [4-6]. This technique is called "adsorption" and has been used extensively in the literature to adsorb microbial cells. Table 1 shows a comparison of these techniques with the mem
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.