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31.
J. S. Abichandani J. H. Wieland Y. T. Shah D. C. Cronauer 《American Institute of Chemical Engineers》1984,30(2):295-303
The liquefaction kinetics of Powhatan No.5 mine coal (Pittsburgh Seam) in the presence of SRC-II recycle solvent at short contact times (<10 min) and temperature and pressure ranges of 573–723 K and 10.3–13.8 MPa is examined in a well-mixed reactor. In the initial stages of liquefaction, while overall coal conversion (tetrahydrofuran solubles) increases with temperature, oil (pentane solubles) is lost with an increase in temperature. An increase in solvent-to-coal ratio results in an increase of conversion. The initial coal particle size distribution, total pressure, and nature of gas phase (nitrogen or hydrogen) have no significant effect on the production of any of the product of liquefaction for contact times up to 10 min. A lumped kinetic model is presented to describe the product distribution. 相似文献
32.
Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have been reviewed by Satterfield [1], Chaudhari and Ramachandran [2], Shah [3,4], Ramachandran and Chaudhari [5], Shah et al. [6], and Herskowitz and Smith [7]. In several industrial processes these reactor designs are modified to achieve a certain specific objective, such as better heat or mass transfer, higher catalyst efficiency, better reactor performance and selectivity, etc. Similarly, specially designed reactors are often used for laboratory kinetic studies or to understand a certain phenomenon. Thus, novel multiphase reactors are becoming important from both academic and industrial viewpoints. Some of the recently introduced novel gas-liquid-solid reactor types are: (a) loop recycle slurry reactors, (b) basket-type reactors, (c) ebullated-bed reactors, (d) internal or external recycle reactors, (e) multistage slurry or packed-bed reactors, (f) column reactors with sieve trays or multiple agitators, (g) gas-induced agitated reactors, and (h) horizontal-packed-bed reactors. are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed. These novel reactor designs are being used in several new commercial processes, and various design aspects, such as hydrodynamics and mass and heat transfer, have been the subject of investigations in the last few years. However, no attempt to review the scattered information on these novel gas-liquid-solid reactors has been made. Therefore, the main objective of this paper is to review important developments in novel gas-liquid-solid reactors. For each type of reactor, advantages, disadvantages, and applications are discussed. Further, the status of information on hydrodynamics and mass transfer parameters and scale-up considerations is reviewed. 相似文献
33.
This paper first outlines an approximate solution to the governing equations for an adiabatic hydroprocessing trickle bed reactor operating in the presence of axial dispersion. The approximate solution agrees very well with the rigorous numerical solution for Peclet numbers greater than approximately three.Using the approximate solution, criteria for significant axial dispersion effect are obtained. These criteria indicate that at high conversions, an adiabatic operation produces a larger axial dispersion effect than the isothermal operation. At low conversions, opposite results are obtained.The derived criteria are used to evaluate the orders of magnitude of Peclet number required to avoid axial dispersion effect in pilot scale adiabatic reactors for (a) residual hydrodesulfurization (b) hydrocracking of gas oils and (c) denitrogenation of shale oils. The calculations indicate that the axial dispersion effect is of less importance in case (c) than in cases (a) and (b).Finally, the role of heat effects on the axial dispersion in a vapor phase fixed bed adiabatic reactor is evaluated. 相似文献
34.
Shah Bhagyashree Alsadoon Abeer Prasad P.W.C. Al-Naymat Ghazi Beg Azam 《Multimedia Tools and Applications》2021,80(14):21339-21361
Multimedia Tools and Applications - Deep learning (DL) is a type of machine learning capable of processing large quantities of data to provide analytic results based on a particular... 相似文献
35.
Huang Tianpeng Huang Deqing Wang Zhikai Dai Xi Shah Awais 《International Journal of Control, Automation and Systems》2021,19(2):698-711
International Journal of Control, Automation and Systems - This paper aims to provide a generic robust controller that is able to manipulate all kinds of quadrotor unmanned aerial vehicle (UAV)... 相似文献
36.
Nadir Shah Ayaz Ahmad Babar Nazir Depei Qian 《Peer-to-Peer Networking and Applications》2016,9(2):356-371
Due to limited radio range and mobility of nodes in mobile ad hoc networks (MANETs), the network partitioning and merging could occur frequently. When structured peer-to-peer (P2P) overlays are running over MANETs, then network partition in the physical network can also cause network partition at the overlay layer. Existing approaches for structured P2P overlay over MANETs do not detect network partition at the overlay layer. This paper proposes a cross-layer approach to detect network partition at the overlay layer for structured P2P overlay over MANETs. Simulation results show that the proposed approach is highly effective and efficient in terms of routing overhead, success ratio and false-negative ratio. 相似文献
37.
Notched concrete beams containing varying amounts of pea gravel aggregate were tested under three-point bend, and their fracture toughness determined. The roughness of the region near the interface between the cement paste and the aggregate was evaluated by digitizing images from a confocal tandem scanning microscope. The average roughness of the paste was found to be related to the fracture parametersK
IC (critical stress intensity factor) and a
c (critical crack extension), as determined by the two-parameter fracture model. The roughness in the proximity of the paste-aggregate interface was generally higher than that of the paste far from the aggregate, and it decreased with the distance from the aggregate. This study indicates that aggregate particles increase the toughness of the cement paste portion of concrete, and that this is an important mechanism for toughening concrete. 相似文献
38.
Razzaq Saad Shah Babar Iqbal Farkhund Ilyas Muhammad Maqbool Fahad Rocha Alvaro 《Neural computing & applications》2023,35(11):8017-8026
Neural Computing and Applications - A lot of different methods are being opted for improving the educational standards through monitoring of the classrooms. The developed world uses Smart... 相似文献
39.
Karimulla Shah Rishav Kumar Sibasis Sahoo R. S. Pais Nirupam Chakraborti 《Materials and Manufacturing Processes》2017,32(10):1201-1208
Data-driven models have been constructed for Dual Phase (DP) and Interstitials Free (IF) steels using an evolutionary approach. DP steel data are utilized from an existing database, while for the IF steels, data generated at an integrated steel plant have been used. The objective function for Ultimate Tensile Strength (UTS) and % elongation, created as data-driven models, is simultaneously optimized for an optimum strength-ductility balance and the results indicate the possibilities of developing steels with better mechanical properties than what are known to have been existing so far. 相似文献
40.