scholarly journals Technique to Investigate Pulverizing and Abrasive Performance of Coals in Mineral Processing Systems

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7300
Author(s):  
Wojciech Grzegorzek ◽  
Daniel Adamecki ◽  
Grzegorz Głuszek ◽  
Aleksander Lutyński ◽  
Daniel Kowol
Keyword(s):  
Fine Powder ◽  
Reduction Process ◽  
Power Input ◽  
Operating Costs ◽  
Coal Bed ◽  
Test Machine ◽  
Testing Procedures ◽  
Coal Particles ◽  
Disc Rotation ◽  
Grinding Conditions

The operating costs of breaking coal particles into fine powder, to achieve optimum combustion for the boilers in a power plant, are made up of power input to carry on an energy intensive comminution mechanism and to overcome friction losses within pulverising machines. The operating costs also include the cost of the replacement of the processing system’s components due to wear. This study presents the development and application of an attrition test machine that enables an investigation of the factors that influence pulverizing efficiency. The attrition tester simulates grinding conditions in real vertical spindle mills. In this kind of mill, as with the tester, the size reduction process results from a shearing action during the redistribution of the coal particles. The redistribution and attrition within the coal bed are forced by movement of the rollers (or by a disc rotation, in the case of the tester). The testing method was oriented toward mechanical properties, i.e., internal friction shear strength, abrasiveness and grindability. This method enables facilitated testing procedures and a more exact simulation of grinding in vertical spindle coal mills. Ball-race mills and Loesche roller mills were used.

Modeling Pressurized Dense Phase Coal Fluidization and Transport

2019 ◽  
Author(s):  
Bradley R. Adams ◽  
Taylor L. Schroedter
Keyword(s):  
Flow Rate ◽  
Particle Interaction ◽  
Drop Out ◽  
Coal Bed ◽  
Flow Ratio ◽  
Feed System ◽  
Horizontal Pipe ◽  
Flow Rates ◽  
Coal Particles ◽  
Coal Flow

Abstract A transient gas-solid model based on CPFD Software’s Barracuda Virtual Reactor was developed for a feed system to a pilot-scale pressurized oxy-coal (POC) reactor. A simplified geometry with a vertical coal hopper feeding into a 0.635-cm diameter horizontal pipe was used to represent key elements of the feed system. Coal particles were transported with 20-atm CO2 gas. The feed system was required to maintain a steady flow of gas and solids at a coal flow rate of approximately 3.8 g/s and a CO2 to coal mass ratio in the range 1–2. Sensitivity of model results to mesh size and particle interaction sub-model settings was assessed. Two design concepts were evaluated. A gravity-fed concept was found to be infeasible due to inadequate coal flow rates even at very high CO2 to coal flow ratios. This was due to gravitational forces being insufficient to move the pressurized coal from the hopper into the CO2 stream at the desired rate. A fluidized bed concept was found to provide the desired coal flow rate and CO2 to coal flow ratio. CO2 injected at the hopper base first fluidized the vertical coal bed before transporting it through a horizontal exit pipe. A second CO2 inlet downstream of the hopper exit pipe was used to dilute the fluidized coal and increase pipe velocities to minimize coal drop out. The amount of coal transported from the hopper was dependent on the net CO2 hopper flow but independent of the CO2 dilution flow. This meant that the coal flow rate and CO2 to coal flow ratio could be controlled independently. Pipe exit coal flow rates were found to fluctuate at levels acceptable for steady burner operation.

Coal Coke Gasification in a Windowed Solar Chemical Reactor for Beam-Down Optics

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Tatsuya Kodama ◽  
Nobuyuki Gokon ◽  
Shu-ich Enomoto ◽  
Shouta Itoh ◽  
Tsuyoshi Hatamachi
Keyword(s):  
Size Fraction ◽  
Chemical Reactor ◽  
Power Input ◽  
Reaction Site ◽  
Coal Particles ◽  
Energy Peak ◽  
Thermochemical Processes ◽  
Efficient Heat Transfer ◽  
Co2 Flow ◽  
Reactor Operating

Solar thermochemical processes, such as solar gasification of coal, require the development of a high temperature solar reactor operating at temperatures above 1000°C. Direct solar energy absorption by reacting coal particles provides efficient heat transfer directly to the reaction site. In this work, a windowed reactor prototype designed for the beam-down optics was constructed at a laboratory scale and demonstrated for CO2 gasification of coal coke using concentrated visible light from a sun-simulator as the source of energy. Peak conversion of light energy to chemical fuel (CO) of 14% was obtained by irradiating a fluidized bed of 500–710 μm coal coke size fraction with a power input of about 1 kW and a CO2 flow-rate of 6.5 dm3 min−1 at normal conditions.

Coal Particles Cleanout Technology in Coal Bed Methane Wells

2012 ◽  
Vol 229-231 ◽  
pp. 2470-2473 ◽  
Author(s):  
Bing Liu ◽  
Yao Guang Qi ◽  
Chao Wang ◽  
Chun Cheng Xu ◽  
Fen Na Zhang ◽  
...  
Keyword(s):  
High Efficiency ◽  
New Technology ◽  
Gas Production ◽  
Coal Bed ◽  
Working Fluid ◽  
Coal Bed Methane ◽  
Skin Damage ◽  
Technology System ◽  
Coal Particles ◽  
Continuous Vacuum

Coal particles cleanout which is regarded as the key technology in the operation of coal bed methane (CBM) wells, play an important part in making steady production. In oil wells, Sand cleanout is operated by circulating a liquid or a multiphase fluid into the wellbore to bring sand particles to the surface. Although the sand cleanout operations have been applied successfully in most wells with high efficiency and negligible leakage, it would leak working fluid into coal bed formation, destroy the structure of coal bed and jam the formed channel of gas production. In this paper, a new continuous vacuum cleanout technology has been developed to effectively remove coal particles in CBM wells by employing a jet pump. The Concentric Tubing String (CTS) which is assembled by 3.5 inch tubing and 1.5 inch tubing is also introduced in, because there is no CCT technology in China at the moment. Detailed structure and principle of the coal particles cleanout technology system are described, while a theoretical model is formulated to optimally design the system based on the coal particles settling experimental data and jet pumping theory. It has been shown from field applications that the coal particles cleanout technology makes significant improvements in achieving high efficiency and preventing leakage in CBM wells. Moreover, the new technology reduces the skin damage and increase the production compared to non-vacuum CBM wells.

scholarly journals Effect of Carbon Addition on Direct Reduction Behavior of Low Quality Magnetite Ore by Reducing Gas Atmosphere

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1404
Author(s):  
Seongrim Song ◽  
Youngjo Kang
Keyword(s):  
Direct Reduction ◽  
Reduction Process ◽  
Hydrocarbon Fuel ◽  
Carbon Composite ◽  
Direct Reduced Iron ◽  
Carbon Efficiency ◽  
Reducing Gas ◽  
Initial Reduction ◽  
Coal Particles ◽  
Composite Pellets

Recently, direct reduced iron (DRI) has been highlighted as a promising iron source for electric arc furnace (EAF)-based steelmaking. The two typical production methods for DRI are gas-based reduction and reduction using carbon composite pellets. While the gas-based reduction is strongly dependent on the reliable supply of hydrocarbon fuel, reduction using ore-coal composite pellets has relatively low productivity due to solid–solid reactions. To overcome the limitations of the above two processes, and to achieve a more efficient direct reduction process of iron ore, the possibility of combining these two methods was investigated. The experiments focused on performing an initial direct reduction using ore-coal composite pellets followed by a second stage gas reduction. It was assumed that the initial reduction of the carbon composite pellets would enhance the efficiency of the subsequent reduction by gas and the total reduction efficiency. The porosity, as well as the carbon efficiency for direct reduction, were measured to determine the optimal conditions for the initial reduction, such as the size ratio of ore and coal particles. Thereafter, further reduction by the reducing gas was carried out to verify the effect of the preliminary reduction. The reduction kinetics of the reducing gas was also discussed.

Structure Optimization and Strength Analysis of CBM Special Anti-Clogging Drainage Pump

2012 ◽  
Vol 479-481 ◽  
pp. 2017-2021
Author(s):  
Wen Tao Qu ◽  
Yi Xiao Guo ◽  
Tao Ren ◽  
Yan Ping Sun
Keyword(s):  
Solid Particles ◽  
Working Environment ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Strength Analysis ◽  
Element Analysis ◽  
Fine Coal ◽  
Coal Particles ◽  
Valve Housing ◽  
Production Areas

There are abundant coal bed methane resources in China, and recovery technology is considered a very important part in the development of coal bed methane. At present, coal bed methane production areas are still adopting the tubing liner pump, but because of the special working environment, in the pumping process, the fine breeze (sand) and other solid particles entering into the pump barrel is likely to cause the pump stuck, pipe string buried by sand and other issues. In view of the above problems, based on the ordinary tubing liner pump, through the increase of the anti-litter bypass style traveling valve housing and fixed valve housing, outside liner jacket, sand reservoir and liquid in tee joint measures we developed a new type of CBM special anti-clogging drainage pump and adopted finite element analysis software ANSYS to complete key parts of strength calculation. The use of this pump will effectively reduces the blocking of fine coal particles (sand) and other solid particles, decreases the pump's checking operation and workload of sand bailing, consequently improves efficiency, reduces overall operating costs.

The Analysis of the Pulverized Coal Deposition in the Pump Cylinder in Drainage and Mining of the Coal Bed Methane (CBM)

2013 ◽  
Vol 712-715 ◽  
pp. 1359-1362 ◽  
Author(s):  
Yan Ping Sun ◽  
Ning Zhao ◽  
Wen Tao Qu
Keyword(s):  
Particle Size ◽  
Coal Particle ◽  
Pulverized Coal ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Size Change ◽  
Lower Velocity ◽  
Pressure Drag ◽  
Coal Particles ◽  
Pump Cylinder

In drainage and mining of the coal bed methane(CBM),pump valve jams caused by the settlement of pulverized coal particles directly affect the normal production of the coal bed methane(CBM).From the study of the pulverized coal particle size,this paper summarizes the law of the pulverized coal particle size change in various stages of the coal bed methane(CBM) production well drainage and ming.By analyzing the pulverized coal particle velocity distribution along the pump cylinder,the viewpoint that the pulverized coal particle has a higher axial velocity in the central part of the settlement and has a lower velocity near the wall surface is put forward to.Based on the theory,the motion track equation of the pulverized coal particle can be got by calculation.Under the condition of considering buoyancy,fluid resistance and pressure drag,instant drop speed of the pulverized coal in water is calculated.

Design and development of a durable series elastic actuator with an optimized spring topology

2021 ◽  
pp. 095440622110203
Author(s):  
Mehmet C Yildirim ◽  
Polat Sendur ◽  
Ahmet Talha Kansizoglu ◽  
Umut Uras ◽  
Onur Bilgin ◽  
...  
Keyword(s):  
Real Life ◽  
Integrated Design ◽  
Torque Control ◽  
Test Machine ◽  
Design Development ◽  
Test Procedures ◽  
Testing Procedures ◽  
Series Elastic Actuator ◽  
Series Elastic

This paper aims to present the integrated design, development, and testing procedures for a state-of-the-art torsion-based series elastic actuator that could be reliably employed for long-term use in force-controlled robot applications. The main objective in designing the actuator was to meet weight and dimensional requirements whilst improving the long-term durability, ensuring high torque output, and containing its total weight. A four-fold design approach was implemented: (i) following recursive design-and-test procedures, an optimal torsional spring topology was unveiled with the help of SIMP (Solid Isotropic Material with Penalization) topology optimization method, (ii) the proposed spring was manufactured and multiple specimens were experimentally tested via a torsional test machine to validate linearity, loading rate response, and mechanical limits, (iii) the actuator’s thermal response was experimentally scrutinized to ensure that the generated heat was dissipated for long-term use, and (iv) the fatigue life of the spring was computed with the help of real-life experiment data. Having concluded the development and verification procedures, two different versions of the actuator were built, and preliminary torque control experiments were conducted. In conclusion, favorable torque tracking with a bandwidth of 19 Hz was achieved while peak-to-peak torque input was 20 Nm.

Use of digital microscopy in process control during the manufacture of rubber-modified thermoplastics

1996 ◽  
Vol 54 ◽  
pp. 616-617
Author(s):  
M. T. Dineen
Keyword(s):  
Ccd Camera ◽  
Operating Costs ◽  
Hard Copy ◽  
Production Plant ◽  
Digital Microscopy ◽  
Nih Image ◽  
Transmission Electron ◽  
Conventional Film ◽  
Product Loss ◽  
Image Collection

The production of rubber modified thermoplastics can exceed rates of 30,000 pounds per hour. If a production plant needs to equilibrate or has an upset, that means operating costs and lost revenue. Results of transmission electron microscopy (TEM) can be used for process adjustments to minimize product loss. Conventional TEM, however, is not a rapid turnaround technique. The TEM process was examined, and it was determined that 50% of the time it took to complete a polymer sample was related to film processing, even when using automated equipment. By replacing the conventional film portion of the process with a commercially available system to digitally acquire the TEM image, a production plant can have the same TEM image in the control room within 1.5 hours of sampling.A Hitachi H-600 TEM Operated at 100 kV with a tungsten filament was retrofitted with a SEMICAPS™ image collection and processing workstation and a KODAK MEGAPLUS™ charged coupled device (CCD) camera (Fig. 1). Media Cybernetics Image-Pro Plus software was included, and connections to a Phaser II SDX printer and the network were made. Network printers and other PC and Mac software (e.g. NIH Image) were available. By using digital acquisition and processing, the time it takes to produce a hard copy of a digital image is greatly reduced compared to the time it takes to process film.

Twin boundary structure of a Y-Ba-Cu-O superconductor

1989 ◽  
Vol 47 ◽  
pp. 168-169
Author(s):  
Yimei Zhu ◽  
Masaki Suenaga ◽  
R. L. Sabatini ◽  
Youwen Xu
Keyword(s):  
Twin Boundary ◽  
Fine Particles ◽  
Imaging Techniques ◽  
Fine Powder ◽  
Orthorhombic Phase ◽  
Boundary Structure ◽  
Crystallographic Axis ◽  
System A ◽  
High Resolution Structure ◽  
Electron Microscopes

The (110) twin structure of YBa2Cu3O7 superconductor oxide, which is formed to reduce the strain energy of the tetragonal to orthorhombic phase transformation by alternating the a-b crystallographic axis across the boundary, was extensively investigated. Up to now the structure of the twin boundary still remained unclear. In order to gain insight into the nature of the twin boundary in Y-Ba-Cu-O system, a study using electron diffraction techniques including optical and computed diffractograms, as well as high resolution structure imaging techniques with corresponding computer simulation and processing was initiated.Bulk samples of Y-Ba-Cu-O oxide were prepared as described elsewhere. TEM specimens were produced by crushing bulk samples into a fine powder, dispersing the powder in acetone, and suspending the fine particles on a holey carbon grid. The electron microscopy during this study was performed on both a JEOL 2000EX and 2000FX electron microscopes operated at 200 kV.

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