Development of a High Pressure Dry Coal Feed System for a 100 kWt Oxy-Coal Reactor

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Taylor Schroedter ◽  
Bradley R. Adams ◽  
Jacob Tuia ◽  
Andrew Fry
Keyword(s):  
Particle Diameter ◽  
Flow Ratio ◽  
Feed System ◽  
Horizontal Pipe ◽  
Bench Scale ◽  
Coal Particles ◽  
Simplifying Assumptions ◽  
Coal Flow ◽  
Co2 Flow ◽  
Burner Operation

Abstract A design concept to feed dry coal from a hopper to a 100 kWt pressurized oxy-coal (POC) reactor using CO2 at 2 MPa was developed using transient computational fluid dynamics (CFD) simulations and bench-scale measurements. The feed system was required to maintain a steady flow of gas and solids at a coal flowrate of approximately 3.8 g/s and a CO2-to-coal mass ratio in the range 1–2. A 5.08-cm diameter vertical coal hopper feeding into a 0.635-cm diameter horizontal pipe was used to represent key elements of the feed system. A fluidized bed concept was found capable of providing the desired coal flowrate and CO2-to-coal flow ratio. Use of separate fluidization and dilution flows allowed the coal flowrate and CO2-to-coal flow ratio to be controlled independently. The amount of coal transported from the hopper was dependent on the net CO2 flow in the hopper but independent of the CO2 dilution flow. Pipe exit coal flowrates were found to fluctuate at levels acceptable for steady burner operation. Tests from a bench-scale apparatus using Pittsburgh 8 coal with a median particle diameter of 50 µm and moisture content of 6% confirmed the feasibility of the fluidization design. However, for a given CO2 fluidization flowrate, experimental coal flowrates were lower than predicted coal flow, in part due to simplifying assumptions of dry, spherical coal particles and smooth piping in the simulations.

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.

Research on the Pneumatic Conveying of the Sand in the Horizontal Pipe Based on FLUENT

2016 ◽  
Vol 11 (2) ◽  
pp. 159-165 ◽  
Author(s):  
Dan-yang Li ◽  
Shu Liu ◽  
Xiao-ning Wang
Keyword(s):  
Particle Diameter ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Theoretical Research ◽  
Pneumatic Conveying ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Actual Measurement ◽  
Fluid Analysis ◽  
Euler Model

Abstract The pneumatic conveying experiment bed has been established to study the flow characteristics of air- solids two-phase flow in horizontal pipeline. Euler model was applied to simulate it based on analysis of Gambit and fluid analysis software-fluent. The simulated results indicated: under the same gas phase conveying flow and pressure, the bigger particle diameter is, the bigger pressure drop is in the horizontal pipeline. The smaller particle diameter is, the more uniform of the particle’s distribution is, and the more easily obtaining the acceleration is. Particle concentration at the bottom of the horizontal pipe is increasing in the axial direction, while close to the tail pipe it will be reduce. The simulated conclusion is consistent with the actual measurement results, herewith rendering some footing for engineering design and theoretical research on pneumatic conveying systems.

The Influence of Coal Rank on the Burning Times of Single Captive Particles

1963 ◽  
Vol 85 (3) ◽  
pp. 183-188 ◽  
Author(s):  
R. H. Essenhigh
Keyword(s):  
Burning Rate ◽  
Particle Diameter ◽  
Porous Matrix ◽  
Coal Rank ◽  
Fixed Carbon ◽  
Initial Particle ◽  
Proportionality Constant ◽  
Coal Particles ◽  
Rank Dependence ◽  
Experimental Values

Measurements of volatile and residue burning times of captive coal particles have shown them to vary in proportion to the square of the initial particle diameter; this was true for each of 10 coals tested. For the volatiles, the measured constant of proportionality was found to be independent of coal rank when allowance was made for swelling, the burning rate apparently being controlled by the diffusional rate of volatile escape through a porous matrix of fixed carbon. For the residues, the experimental “square-law” relation confirms Nusselt’s prediction; and agreement between predicted and experimental values of the proportionality constant was found to be good. An apparent rank dependence, showing shorter burning times with less fixed carbon, was simply a consequence of there being less fixed carbon to burn. There was no influence of rank-dependent “reactivity.” The relevance of the results to flames is also discussed.

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.

Experimental Study of Sand Particle Concentration Profiles in Straight and Pipe Elbow for Horizontal Multiphase Flows

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
N. R. Kesana ◽  
R. Vieira ◽  
B. S. McLaury ◽  
S. A. Shirazi
Keyword(s):  
Oil And Gas ◽  
Particle Diameter ◽  
Sand Particle ◽  
Horizontal Pipe ◽  
Oil And Gas Producers ◽  
Pipe Elbow ◽  
Fluid Velocities ◽  
Erosion Models ◽  
The Face ◽  
Concentration Measurements

Sand production is one of the major concerns for oil and gas producers. If production fluid velocities are not controlled properly, the produced sand may erode the pipelines which may result in pipe failures and halt the production causing economical losses as well as environmental issues. In order to better understand the erosion mechanism and improve current erosion models, it would be beneficial to identify the distribution of sand flowing inside the pipe. Therefore, sand sampling was performed at five different locations inside a 0.0732 m (3 in.) diameter horizontal pipe at L/D ∼ 150 using a pitot-style tube 6.35 mm (0.25 in.) in diameter. The probe was moved transversely from the top of the pipe and the face of the probe is facing the fluid flow to achieve sampling close to isokinetic conditions. Additionally, sampling experiments were conducted using the fixed mounted ports at the pipe wall. Using the fixed mounted ports, sampling is conducted both in a straight pipe section and elbow section. Experiments were performed in two different multiphase flow patterns (slug and wavy-annular) using two different particle sizes (150 μm and 300 μm) and three different liquid viscosities (1 cP, 10 cP, 40 cP). The influence of particle diameter, liquid viscosity, and the flow pattern on the sand distribution profiles will be discussed. From the experimental data, the recommended approaches for flowing concentration measurements are discussed. Finally, the implications of the sand concentration measurements on erosion are mentioned.

scholarly journals Electrochemical Treatment of Mixed and Hazardous Waste

1995 ◽  
Vol 412 ◽  
Author(s):  
J. Dziewinski ◽  
S. Marczak ◽  
E. Nuttall ◽  
W. Smith
Keyword(s):  
Organic Compounds ◽  
National Laboratory ◽  
Experimental Studies ◽  
Toxic Metal ◽  
Electrochemical Treatment ◽  
Electrochemical Process ◽  
Feed System ◽  
Chlorinated Organic Compounds ◽  
Bench Scale ◽  
Mixed Wastes

AbstractLos Alamos National Laboratory (LANL) and The University of New Mexico are jointly developing an electrochemical process for treating hazardous and radioactive wastes. The wastes treatable by the process include toxic metal solutions, cyanide solutions, and various organic wastes that may contain chlorinated organic compounds. The main component of the process is a stack of electrolytic cells with peripheral equipment such as a rectifier, feed system, tanks with feed and treated solutions, and a gas-venting system. During the treatment, toxic metals are deposited on the cathode, cyanides are oxidized on the anode, and organic compounds are anodically oxidized by direct or mediated electrooxidation, depending on their type. Bench scale experimental studies have confirmed the feasibility of applying electrochemical systems to processing of a great variety of hazardous and mixed wastes. The operating parameters have been defined for different waste compositions using surrogate wastes. Mixed wastes are currently treated at bench scale as part of the treatability study.

scholarly journals Numerical investigation of solid-liquid slurry flow through an upward-facing step

2013 ◽  
Vol 61 (2) ◽  
pp. 126-133g ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Particle Density ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Expansion Ratio ◽  
Water Mixture ◽  
Horizontal Pipe ◽  
Liquid Slurry ◽  
Solid Liquid

Abstract The flow of a solid-water mixture through an upward-facing step in a channel is numerically investigated. The effect of expansion ratio, mean solids volume fraction and particle diameter on the velocity field, pressure distribution and solid volume fraction field is studied. Expansion ratios of 0.50 and 0.67, particle diameter of 125 μm and 440 μm and mean solid volume fraction between 0.05 and 0.20 are considered. Particle density is 2465 kg m-3. An Eulerian twofluid model is used to simulate the flow. Due to the lack of experimental data, the model was validated by comparison to other numerical investigations and to experimental data about the horizontal pipe case. Afterwards, it is studied the effect of the above mentioned parameters upon the degree of coupling between the phases and the extension of the disturbance region in the pressure and solid volume fraction fields downstream the step. Parameters of engineering interest, such as the reattachment length and the pressure recovery downstream the enlargement, are investigated.

Studies on Coal Ignition and Combustion Characteristics

2017 ◽  
Author(s):  
Xue Chen ◽  
MingYan Gu ◽  
XianHui He ◽  
Dan Yan ◽  
Jimin Wang ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Coal Particle ◽  
Gas Flow ◽  
Ignition Time ◽  
Particle Diameter ◽  
Combustion Characteristics ◽  
Gas Temperature ◽  
Flow Temperature ◽  
Particle Ignition ◽  
Coal Particles

A 2-D numerical model of flow, heat transfer, and combustion of coal particles in a laminar gas flow at O2/CO2 atmosphere was developed based on the Eulerian-Lagrangian methodology. The gas-phase combustion was modeled using the GRI-Mech 3.0. The motion of coal particles was simulated using a trajectory model. The model was employed to study the coal ignition time, temperature and mass changes. The effects of particle diameter, the flow temperature and oxygen concentration on the ignition time and the combustion characteristics of coal particles were also investigated. The results obtained show that smaller size particle experiences a shorter ignition time with a higher coal temperature. A higher gas temperature leads to a shorter coal particle ignition time; increasing the flow temperature the difference in the ignition time of different sized coal particles decreases. The coal particle ignition time is decreased when the oxygen concentration is increased.

scholarly journals Flow Characteristics of Multiphase Glass Beads-Water Slurry through Horizontal Pipeline using Computational Fluid Dynamics

2019 ◽  
Vol 16 (2) ◽  
pp. 6605-6623 ◽  
Author(s):  
Shofique Uddin Ahmed ◽  
Rajesh Arora ◽  
Om Parkash
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Control Volume ◽  
Particle Diameter ◽  
Solid Particles ◽  
Slurry Flow ◽  
Two Phase ◽  
Horizontal Pipe

Over the decades conveying solid particles through pipelines is a prevalent usage for many industries like food industries, pharmaceutical, oil and gas-solid handling, power generations etc. In the present study, slurry flow through 54.9 mm diameter and 4 m long horizontal pipe with solid particle diameter 0.125 mm and specific gravity 2.47 has been numerically analysed using a granular version of Eulerian two-phase model and RNG K-  model. The solid particles are considered as mono-dispersed in the Eulerian model. These models are available in computational fluid dynamics (CFD) fluent software package. Non-uniform structured three-dimensional mesh with a refinement near wall boundary region has been selected for discretising the flow domain, and governing equations are solved using control volume finite difference method. Simulations are conducted at velocity varying from 1 m/s to 5 m/s and efflux concentration varying from 0.1 to 0.5 by volume. Different slurry flow parameters such as solid concentration distribution, velocity distribution, pressure drop etc. have been analysed from the simulated results. The simulated results of pressure drop are correlated with the experimental data available in previous literature and are found to be in excellent compliance with the experimental data.

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