Research on Flow Characteristics of Pulverized Coal in a High Pressure Blow Tank

2012 ◽  
Author(s):  
Wenhao Pu ◽  
Peng Lu ◽  
Chen Yue ◽  
Dong Han
Keyword(s):  
High Pressure ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Fluid Model ◽  
Particle Diameter ◽  
Flow Characteristics ◽  
Differential Pressure ◽  
Pulverized Coal ◽  
Solid Mass

In the present study, the flow characteristics of a top discharge blow tank at high pressure were investigated. Experiments on discharge properties of pulverized coal in dense-phase pneumatic conveying system with a high pressure blow tank were carried out. The influences of fluidizing velocity, pressurizing velocity, transporting differential pressure, sending pressure in the blow tank and pulverized coal diameter on the solid mass flow rate were studied. The experimental results indicated that the ratio of fluidizing velocity to pressurizing velocity was of great importance on the solid mass flow rate and there existed an optimum range. The solid mass flow rate increased as the transporting differential pressure and sending pressure increased. The increase of particle diameter led to the decrease of the solid mass flow rate. A model for determining the solid mass flow rate has been formulated using dimensional analysis. It was found that the calculation results were in good agreement with the experimental data. Finally, a kinetic–frictional model, which treated the kinetic and frictional stresses in an additive manner, was incorporated into the two fluid model based on the kinetic theory of granular flow to simulate the transient behaviors of the high pressure blow tank.

The Investigation of Back-Mixing Particles near Dust Outlet in Cyclone Separator with Tangential Inlet

2011 ◽  
Vol 239-242 ◽  
pp. 2142-2148
Author(s):  
Hui Min Tan ◽  
Jian Jun Wang ◽  
You Hai Jin
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Particle Diameter ◽  
Particle Mass ◽  
Cyclone Separator ◽  
Axial Distribution ◽  
Computational Fluid Dynamics Analysis ◽  
Back Mixing ◽  
Tangential Inlet

Based on experimental and computational fluid dynamics analysis, the phenomenon of particle back-mixing near the dust outlet in cyclone separator with tangential inlet was studied. The results show that particle back-mixing appears near the dust outlet geometry. Particle back-mixing can be divided into dust hopper back-mixing and discharge cone back-mixing for different generation mechanism. The upward flow coming from dust hopper, which occupies 17.7% of the inlet gas, can induce dust hopper back-mixing. The particle mass flow rate that caused by dust hopper back-mixing occupies 46.6% of total inlet particle mass flow rate. Precessing vortex core, bias flow and high turbulent intensity near the dust outlet can induce discharge cone back-mixing. For both dust hopper back-mixing and discharge cone back-mixing, particle back-mixing is serious near the dust outlet geometry, which occupies 56.8% of total inlet particle mass flow rate. Particle which is smaller than 18μm can mix backward. The axial distribution of particle concentration decreases sharply in a range of 1.5 D (cyclone diameter) height above the dust discharge port. At last, only 2.6% of back-mixing particles with diameter no bigger than 13μm escape from vortex finder. This effect on separator efficiency increases with the particle diameter decreases.

scholarly journals Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee
Keyword(s):  
Boundary Conditions ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Jet Pump ◽  
Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

A Novel X-Ray Based High Pressure Mass Flow Rate Sensor for MPD Operations

2018 ◽  
Author(s):  
Vivek Singhal ◽  
Pradeep Ashok ◽  
Eric van Oort ◽  
Paul Park
Keyword(s):  
High Pressure ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
X Ray ◽  
Rate Sensor

scholarly journals Ballast Flow Characteristics of Discharging Pipeline in Shield Slurry System

2019 ◽  
Vol 9 (24) ◽  
pp. 5402
Author(s):  
Yang Wang ◽  
Yimin Xia ◽  
Xuemeng Xiao ◽  
Huiwang Xu ◽  
Peng Chen ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Slurry Flow ◽  
Volumetric Concentration ◽  
Mass Percentage ◽  
Pipe System ◽  
Pipeline Wall ◽  
Slurry Flow Rate

We adopted two-way coupling of discrete and finite elements to examine the non-spherical ballast flow characteristics in a slurry pipe system during a shield project. In the study, we considered the slurry rheological property and the flake shape of the ballast. A ballast size between 17 and 32 mm under different slurry flow rates and ballast volumetric concentration conditions was investigated for determining the law through which the mass flow rate, detained mass percentage, and ballast distribution state are influenced. The results indicate that increasing slurry flow rate and the ballast volumetric concentration increase the mass flow rate; the influence of the latter is stronger. Increases in both in the slurry flow rate and the ballast volumetric concentration can reduce the detained mass percentage in the slurry discharging pipeline, whereas increasing the ballast size has the opposite effect. The increase in both the slurry flow rate and the ballast size changes the ballast motion state. Experiments verified the numerical lifting model of the ballast in the vertical pipeline. The measurements of the actual pipeline wall thickness verified that the simulation results regarding the ballast distribution were accurate.

An Experimental Study of the Flow of R-407C in an Adiabatic Spiral Capillary Tube

2009 ◽  
Vol 1 (4) ◽  
Author(s):  
M. K. Mittal ◽  
R. Kumar ◽  
A. Gupta
Keyword(s):  
Experimental Data ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Flow Rates ◽  
Tube Test ◽  
Mass Flow Rates ◽  
R 134A

The objective of this study is to investigate the effect of coiling on the flow characteristics of R-407C in an adiabatic spiral capillary tube. The characteristic coiling parameter for a spiral capillary tube is the coil pitch; hence, the effect of the coil pitch on the mass flow rate of R-407C was studied on several capillary tube test sections. It was observed that the coiling of the capillary tube significantly reduced the mass flow rate of R-407C in the adiabatic spiral capillary tube. In order to quantify the effect of coiling, the experiments were also conducted for straight a capillary tube, and it was observed that the coiling of the capillary tube reduced the mass flow rate in the spiral tube in the range of 9–18% as compared with that in the straight capillary tube. A generalized nondimensional correlation for the prediction of the mass flow rates of various refrigerants was developed for the straight capillary tube on the basis of the experimental data of R-407C of the present study, and the data of R-134a, R-22, and R-410A measured by other researchers. Additionally, a refrigerant-specific correlation for the spiral capillary was also proposed on the basis of the experimental data of R-407C of the present study.

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

2018 ◽  
Vol 233 (3) ◽  
pp. 937-948
Author(s):  
Jiarui Zhang ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Laval Nozzle ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Engine Performance ◽  
Orifice Diameter ◽  
Two Phase ◽  
Convergent Nozzle

To predict engine performance and further instruct the integral engine design, a more reasonable and accurate numerical model of the two-phase underwater ramjet was introduced in this article by considering the bubble formation process. Two-fluid model was used to examine the bubbly flow in the nozzle and its mathematical model was solved by a fourth-order Runge–Kutta method. Subsequently, the influences of vessel velocity, gas mass flow rate, navigational depth, and orifice diameter of the bubble injector on the performance of the engine were discussed. Results show that, compared with convergent nozzle, Laval nozzle is proved to improve the thrust of the engine, especially at relatively high velocity and gas mass flow rate. With the other conditions fixed, there is an optimum vessel velocity for the ramjet, in which maximum thrust is generated. And a smaller orifice diameter always promotes the engine performance, while this promotion is negligible when the orifice diameter is smaller than 1 mm. Besides, increasing backpressure will cause serious performance drop, which means that the the two-phase underwater ramjet is only efficient for shallow depths.

Flow Characteristics on Fluidized Powder Conveying in a Horizontal Rectangular Channel

2015 ◽  
Author(s):  
Koichiro Ogata ◽  
Sumito Yamashita ◽  
Tomoya Hirose
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Glass Beads ◽  
Horizontal Channel ◽  
Solid Loading ◽  
Loading Ratio ◽  
Minimum Fluidizing Velocity

This study experimentally examined the dense phase pneumatic conveying in a horizontal rectangular channel using the fluidizing air. The powder used is PVC belong to Geldart A particle, where the mean diameter is 151μm, the particle density is 1382kg/m3 and the minimum fluidizing velocity is 9.0mm/s. As the experimental conditions, the fluidizing velocity at the bottom of a vessel and the horizontal channel has been changed. Also, the mass of transported powder, the supply air pressure and the height of powder bed inside a vessel were measured. In the case of PVC, we confirmed the flow characteristics of the powder conveying and air pressure. Further, we found that the fluidizing air to the bottom of a vessel was required to the powder conveying of this system, and that the fluidizing velocity at the horizontal channel needs to be larger than the minimum fluidizing velocity. These results were also obtained on the previous study when two kinds of glass bead was used. The mass flow rate and solid loading ratio were estimated by the measured data of the mass of transported powder. In addition, these results were compared with the conveying characteristic of two kinds of glass beads belongs to Geldart A and B particle. As a result, the mass flow rate and solid loading ratio of PVC were smaller than that of two kinds of glass beads.

Dynamic Reference Value Generation for the Control of a Diesel Engine With HP- and LP-EGR

2010 ◽  
Author(s):  
Matthias Mrosek ◽  
Rolf Isermann
Keyword(s):  
High Pressure ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Exhaust System ◽  
Reference Value ◽  
Low Pressure ◽  
Gas Composition ◽  
Air Mass ◽  
Intake System

A combination of a low-pressure EGR and a high-pressure EGR for Diesel engines can effectively reduce the NOx emissions. In comparison to a conventional high-pressure EGR, the combination with a low-pressure EGR introduces an additional degree of freedom for the air path control. From control perspective the weaker couplings with the charging pressure and the dynamics of the gas composition in the intake and exhaust system are the major differences between the low-pressure and the high-pressure EGR. The lower gas temperature of the low-pressure EGR further reduces the emissions. A control oriented model is presented to control the gas composition in the intake system. Therefore a reference value transformation converts a desired air mass flow rate into a desired gas composition in the intake system. Depending on the dynamical gas compositions in the intake and exhaust system, the reference value of the desired gas composition results in a setpoint for a high-pressure EGR mass flow rate controller. Due to the faster dynamics of the high-pressure EGR, this controller accounts for the fast dynamical effects in the gas system. The presented control structure in combination with the reference value generation is invariant to model and sensor uncertainties and results stationary in an air mass flow rate control. As additional control variable, the intake temperature is controlled by the low-pressure EGR mass flow rate. A calibrated desired temperature delivers the setpoint for a low-pressure EGR mass flow rate controller.

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