The New Fluidized Bed Thermo-Chemical Treatment in Chemically Active Powders – CFD Analysis of the Method

2014 ◽  
Vol 902 ◽  
pp. 82-87
Author(s):  
Tomasz Babul ◽  
Aleksander Ciski ◽  
Paweł Oleszczak
Keyword(s):  
Computer Simulation ◽  
Fluidized Bed ◽  
Chemical Treatment ◽  
Layer Structure ◽  
Inert Gas ◽  
Cfd Analysis ◽  
Specific Calculation ◽  
New Type ◽  
Carburized Layer ◽  
Carburizing Process

The paper describes the principles of carrying out of a new type of fluidized bed thermo-chemical treatment in chemically active powders with fluidization by chemically inert gas. The article presents selected results of a computer simulation of chemically active fluidized bed phenomena used in the thermo-chemical treatment of steel. For this purpose, a numerical model of the fluidized bed with a specific calculation area, has been prepared. The results of CFD (Computational Fluid Dynamics) computer simulation of temperature distribution and fluidizing gas mass distribution along the walls of samples placed in the fluidized bed are presented. Results of exemplary carburizing process are given. Metallographic observations and hardness measurements confirm the correctness of the of the carburized layer structure, which was formed on the C22 unalloyed carbon steel.

scholarly journals Acetylene Flow Rate as a Crucial Parameter of Vacuum Carburizing Process of Modern Tool Steels

2016 ◽  
Vol 61 (4) ◽  
pp. 2009-2012 ◽  
Author(s):  
P. Rokicki ◽  
K. Dychton
Keyword(s):  
Chemical Treatment ◽  
Negative Impact ◽  
Aerospace Industry ◽  
Tool Steels ◽  
Vacuum Carburizing ◽  
Layer Characteristic ◽  
Process Methodology ◽  
Carburized Layer ◽  
Treatment Procedures ◽  
Carburizing Process

Abstract Carburizing is one of the most popular and wide used thermo-chemical treatment methods of surface modification of tool steels. It is a process based on carbon diffusive enrichment of the surface material and is applied for elements that are supposed to present higher hardness and wear resistance sustaining core ductility. Typical elements submitted to carburizing process are gears, shafts, pins and bearing elements. In the last years, more and more popular, especially in highly advanced treatment procedures used in the aerospace industry is vacuum carburizing. It is a process based on chemical treatment of the surface in lower pressure, providing much higher uniformity of carburized layer, lower process cost and much lesser negative impact on environment to compare with conventional carburizing methods, as for example gas carburizing in Endo atmosphere. Unfortunately, aerospace industry requires much more detailed description of the phenomena linked to this process method and the literature background shows lack of tests that could confirm fulfilment of all needed requirements and to understand the process itself in much deeper meaning. In the presented paper, authors focused their research on acetylene flow impact on carburized layer characteristic. This is one of the most crucial parameters concerning homogeneity and uniformity of carburized layer properties. That is why, specific process methodology have been planned based on different acetylene flow values, and the surface layer of the steel gears have been investigated in meaning to impact on any possible change in potential properties of the final product.

scholarly journals The Limits of Learning: Exploration, Generalization, and the Development of Learning Traps

2018 ◽  
Author(s):  
Alexander Rich ◽  
Todd Matthew Gureckis
Keyword(s):  
Decision Making ◽  
Computer Simulation ◽  
Adaptive Behavior ◽  
False Belief ◽  
Complex Environments ◽  
Extensive Experience ◽  
Present Evidence ◽  
Fundamental Limit ◽  
New Type ◽  
Series Of Experiments

Learning usually improves the accuracy of beliefs through the accumulation of experience. But are there limits to learning that prevent us from accurately understanding our world? In this paper we investigate the concept of a “learning trap”—the formation of a stable false belief even with extensive experience. Our review highlights how these traps develop though the interaction of learning and decision making in unknown environments. We further document a particularly pernicious learning trap driven by selective attention, a mechanism often assumed to facilitate learning in complex environments. Using computer simulation we demonstrate the key attributes of the agent and environment that lead to this new type of learning trap. Then, in a series of experiments we present evidence that people robustly fall into this trap, even in the presence of various interventions predicted to meliorate it. These results highlight a fundamental limit to learning and adaptive behavior that impacts individuals, organizations, animals, and machines.

Computer simulation of fluidized bed granulation

1990 ◽  
Vol 1 (2) ◽  
pp. 77-87 ◽  
Author(s):  
Ken-Ichi Sugimori ◽  
Shoichi Mori ◽  
Yoshiaki Kawashima
Keyword(s):  
Computer Simulation ◽  
Fluidized Bed

scholarly journals A new type of experimentally proposed in situ heat/gas clean foam fracturing fluid system

2020 ◽  
Vol 10 (8) ◽  
pp. 3419-3436
Author(s):  
Kuangsheng Zhang ◽  
Zhenfeng Zhao ◽  
Meirong Tang ◽  
Wenbin Chen ◽  
Chengwang Wang ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Pressure Coefficient ◽  
System Optimization ◽  
Inert Gas ◽  
Working Fluid ◽  
Fluid Loss ◽  
Fracturing Fluid ◽  
Fluid System ◽  
New Type

Abstract When cold fluid is injected into low-temperature, low-pressure, low-permeability reservoirs containing wax-bearing heavy oil, cryogenic paraffin deposition and heavy oil condensation will occur, thus damaging the formation. Moreover, the formation pressure coefficient is low and the working fluid flowback efficiency is low, which affects the fracturing stimulation effect. Therefore, an in situ heat/gas clean foam fracturing fluid system is proposed. This system can ensure that conventional fracturing fluid can create fractures and carry proppant in the reservoir, generate heat in situ to avoid cold damage, reduce the viscosity, and improve the fluidity of crude oil. The in situ heat fracturing fluid generates a large amount of inert gas while generating heat, thus forming foam-like fracturing fluid, reducing fluid loss, improving proppant-carrying performance, improving gel-breaking performance, effectively improving crack conductivity, and is clean and environmentally friendly. Based on the improved existing fracturing fluid system, in this paper, a new type of in situ heat fracturing fluid system is proposed, and a system optimization evaluation is conducted through laboratory experiments according to the performance evaluation standard of water-based fracturing fluid. Compared with the traditional in situ heat fracturing fluid system, the fracturing fluid system proposed in this study generates a large amount of inert gas and form foam-like fracturing fluid, reduces fluid loss, enhances the proppant-carrying capacity and gel-breaking performance, improves crack conductivity, the gel without residue and that the gel-breaking liquid is clean and harmless.

scholarly journals Effect of Pressure on Second-Generation Pressurized Fluidized Bed Combustion Plants

1994 ◽  
Vol 116 (2) ◽  
pp. 345-351 ◽  
Author(s):  
A. Robertson ◽  
D. Bonk
Keyword(s):  
Gas Turbine ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Second Generation ◽  
Electrical Power ◽  
Fluidized Bed Combustion ◽  
Fuel Gas ◽  
Combustion Gas ◽  
New Type ◽  
Pressurized Fluidized Bed Combustion

In the search for a more efficient, less costly, and more environmentally responsible method for generating electrical power from coal, research and development has turned to advanced pressurized fluidized bed combustion (PFBC) and coal gasification technologies. A logical extension of this work is the second-generation PFBC plant, which incorporates key components of each of these technologies. In this new type of plant, coal is devolatilized/carbonized before it is injected into the PFB combustor bed, and the low-Btu fuel gas produced by this process is burned in a gas turbine topping combustor. By integrating coal carbonization with PFB coal/char combustion, gas turbine inlet temperatures higher than 1149°C (2100°F) can be achieved. The carbonizer, PFB combustor, and particulate-capturing hot gas cleanup systems operate at 871°C (1600°F), permitting sulfur capture by time-based sorbents and minimizing the release of coal contaminants to the gases. This paper presents the performance and economics of this new type of plant and provides a brief overview of the pilot plant test programs being conducted to support its development.

Process Temperature Effect on Surface Layer of Vacuum Carburized Low-Alloy Steel Gears

2015 ◽  
Vol 227 ◽  
pp. 425-428 ◽  
Author(s):  
Kamil Dychtoń ◽  
Paweł Rokicki ◽  
Andrzej Nowotnik ◽  
Marcin Drajewicz ◽  
Jan Sieniawski
Keyword(s):  
Surface Layer ◽  
Chemical Treatment ◽  
Power Transmission ◽  
High Strength ◽  
Aircraft Engine ◽  
Carbon Diffusion ◽  
Process Temperature ◽  
Process Time ◽  
Vacuum Carburizing ◽  
Carburized Layer

Gears, due to their complex shape, carried load and required accuracy are ones of most complex aircraft engine parts. Single tooth damage usually breaks the power transmission and causes failure of the entire gear system. Adequate sustainability and guarantees of transmission is therefore a condition for secure operation of whole device. Particularly high requirements for reliability are put to transmissions used in the aerospace industry. Due to the loads which are transmitted through the gears, the materials used by the manufacturer must have not only high strength but also show the abrasion resistance of the surface layer and the ductility of the core. Thermo-chemical treatment of industrial gears is a fundamental process, which gives them adequate mechanical properties regarding loads they carry and the surface conditions of work. The most promising method in the discussed field is vacuum carburizing, which by its specification of work significantly reduce the emission of CO2and the duration of the process, without reducing the quality of the final product. The main aim of the paper is to present criteria for selection of carburizing parameters (mainly temperature increase) as a part of thermo-chemical treatment process performed using vacuum methods. Proper (higher to compare with conventional methods) carburizing process temperature is crucial in programming of carbon diffusion process meaning in process time and final carburized layer characteristics as carbon profile and homogeneity of the carburized layer.

2nd Generation PFB Plant With W501G Gas Turbine

2005 ◽  
Author(s):  
A. Robertson ◽  
Zhen Fan ◽  
H. Goldstein ◽  
D. Horazak ◽  
R. Newby ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Fluidized Bed ◽  
Conceptual Design ◽  
Combined Cycle ◽  
Department Of Energy ◽  
United States Department ◽  
Plant Design ◽  
2Nd Generation ◽  
New Type

Research has been conducted under United States Department of Energy (USDOE) Contract DE-AC21-86MC21023 to develop a new type of coal-fired, combined cycle, gas turbine-steam turbine plant for electric power generation. This new type of plant — called a 2nd Generation or Advanced Pressurized Fluidized Bed Combustion (APFB) plant — offers the promise of efficiencies greater than 48 percent (HHV) with both emissions and a cost of electricity that are significantly lower than those of conventional pulverized-coal-fired plants with scrubbers. In the 2nd Generation PFB plant coal is partially gasified in a pressurized fluidized bed reactor to produce a coal derived syngas and a char residue. The syngas fuels the gas turbine and the char fuels a pressurized circulating fluidized bed (PCFB) boiler that powers the steam turbine and supplies hot vitiated air for the combustion of the syngas. A conceptual design and an economic analysis was previously prepared for this plant, all based on the use of a Siemens Westinghouse W501F gas turbine with projected gasifier, PCFB boiler, and gas turbine topping combustor performance data. Having tested these components at a pilot plant scale and observed better than expected performance, the referenced conceptual design has been updated to reflect that test experience and to incorporate more advanced turbines e.g. a Siemens Westinghouse W501G gas turbine and a 2400 psig/1050°F/1050°F/2-1/2 in. Hg steam turbine. This paper presents the performance and economics of the updated plant design along with data on some alternative plant arrangements.

Numerical Simulation on Thermal Field in the Fluidized Bed with Internal Heating Plates

2013 ◽  
Vol 690-693 ◽  
pp. 3162-3165
Author(s):  
Ji Hai Duan ◽  
Qi Wang
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Thermal Field ◽  
Side Reactions ◽  
Internal Heating ◽  
New Type ◽  
Over Time

Fluidized beds are widely used in the factories. However, the traditional heating methods can not meet the actual needs. Then we propose a new type fluidized-bed, which can effectively resolve the problem occurred in conventional fluidized-bed. The temperature of the reaction gas can be distributed uniformly in the new type fluidized-bed, the bed pressure drop is relatively stable over time. The above situations are conducive to the reactions stability, and reduce the occurrence of side reactions as well.

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