scholarly journals Systematic Study of Pressure Fluctuation in the Riser of a Dual Inter-Connected Circulating Fluidized Bed: Using Single and Binary Particle Species

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 890 ◽  
Author(s):  
Yusif A. Alghamdi ◽  
Zhengbiao Peng ◽  
Caimao Luo ◽  
Zeyad Almutairi ◽  
Behdad Moghtaderi ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Pressure Fluctuation ◽  
Circulating Fluidized Bed ◽  
Pressure Fluctuations ◽  
Single Species ◽  
Terminal Velocity ◽  
Operating Conditions ◽  
Cold Flow ◽  
Fluidization Regime ◽  
Spectrum Density

This study systematically investigates the pressure fluctuation in the riser of a dual interconnected circulating fluidized bed (CFB) representing a 10 kWth cold-flow model (CFM) of a chemical-looping combustion (CLC) system. Specifically, a single-species system (SSS) and a binary-mixtures system (BMS) of particles with different sizes and densities were utilized. The pressure fluctuation was analyzed using the fast Fourier transform (FFT) method. The effect of introducing a second particle, changing the inventory, composition (i.e., 5, 10 to 20 wt.%), particle size ratio, and fluidization velocity were investigated. For typical SSS experiments, the results were similar to those scarcely reported in the literature, where the pressure fluctuation intensity was influenced by varying the initial operating conditions. The pressure fluctuations of BMS were investigated in detail and compared with those obtained from SSS experiments. BMS exhibited different behaviour; it had intense pressure fluctuation in the air reactor and in the riser when compared to SSS experiments. The standard deviation (SD) of the pressure fluctuation was found to be influenced by the fluidization regime and initial operating conditions, while the power spectrum density (PSD) values were more sensitive to the presence of the particles with the higher terminal velocity in the binary mixture.

Investigation on Complex Pressure Fluctuations in a Gas-Solids Circulating Fluidized Bed Rieser

2012 ◽  
Vol 538-541 ◽  
pp. 610-615
Author(s):  
Jun Xu ◽  
Xing Xing Chen ◽  
Gui Lei Wang ◽  
Yao Dong Wei
Keyword(s):  
Fluidized Bed ◽  
Pressure Fluctuation ◽  
Circulating Fluidized Bed ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Axial Direction ◽  
High Amplitude ◽  
Solid Mass ◽  
Two Phase ◽  
Mass Fluxes

The experiment is carried out in a 13-meter-high circulating fluidized bed(CFB) to investigate gas-solid two-phase flow by pressure sensor. The axial pressure and pressure fluctuation are measured in different solid mass fluxes. With the solid mass flux increasing, pressure gradually increases, and pressure gradually decreases along the riser upwards. The characteristic of pressure fluctuation in the riser is analyzed, which indicates that pressure fluctuation in the riser originates from the inlet. The intensity of the pressure fluctuation decreases along the riser upwards. This pressure fluctuation is composed of two types: one is of low frequency and high amplitude, which is resulted from unstable feeding to the riser and keeps coherent along the axial direction. And the other is of high frequency and low amplitude, which is the result of a variety of factors, such as cluster movement, gas-solid interaction and gas velocity fluctuation.

Detection of gas-solid flow faults of a circulating fluidized bed using pressure fluctuations in wind caps

2016 ◽  
Vol 33 (7) ◽  
pp. 2240-2251 ◽  
Author(s):  
Hua-wei Jiang ◽  
Jian-qiang Gao ◽  
Hong-wei Che ◽  
Jun-fu Lu ◽  
Fu-mao Wang ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pressure Fluctuations ◽  
Solid Flow

Dynamic simulation of the circulating fluidized bed loop performance under the various operating conditions

2019 ◽  
Vol 233 (7) ◽  
pp. 901-913 ◽  
Author(s):  
Seongil Kim ◽  
Sangmin Choi ◽  
Jari Lappalainen ◽  
Tae-Ho Song
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Heat Transfer Rate ◽  
Dynamic Simulation ◽  
Transfer Rate ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Operating Conditions ◽  
Temperature Behavior ◽  
Furnace Temperature

In a circulating fluidized bed boiler, the large thermal mass and flow characteristics of the solids strongly affect the transient response of the circulating fluidized bed loop temperature, which determines the heat transfer rate to steam flow. Therefore, it is essential to interpret the dynamic response of the solid behavior in the circulating fluidized bed loop for the stable and efficient operation of the circulating fluidized bed boiler. In this study, the dynamic simulation of the solid behavior along with the flue gas flow in a circulating fluidized bed loop was performed by applying the core-annulus approach for the solid-gas flow inside the furnace and selected models for other physical phenomena of the fluidized bed. The circulating fluidized bed loop of a commercial boiler was selected as the target system. Especially, the model simulates the characteristics of the solid behavior, such as the local solid mass distribution, and the solid flow inside the furnace and the circulating solid according to the various operating conditions. These aspects are difficult to measure and quantify in a real power plant. In this paper, the simulated furnace temperature behavior as the representative performance parameter of the circulating fluidized bed loop was discussed along with the qualitative operation experiences reported in the literature. The operating conditions include the feed rate of fuel and air, the particle size, the solid inventory and the solid circulation rate. Furnace temperature behavior was reproduced through the simulation for each operating case in the literature and was analyzed with the solid behavior along with the combustion rate and heat transfer rate of the circulating fluidized bed loop. The simulation enables quantitative evaluation of the effect of the solid behavior on the temperatures of the furnace and return part in the various operating conditions.

Horizontal Pressure Fluctuation in Bubbling Fluidized Bed

2003 ◽  
Author(s):  
Vesa V. Walle´n
Keyword(s):  
Pressure Gradient ◽  
Fluidized Bed ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Middle Part ◽  
Biomass Combustion ◽  
Bottom Part ◽  
Pressure Transducers ◽  
Bubbling Fluidized Bed ◽  
Horizontal Pressure

Pressure measurements were conducted in a two-dimensional hot atmospheric bubbling fluidized bed reactor in the laboratory of Energy and Process Engineering at Tampere University of Technology. A set of six fast pressure transducers was used to detect the rapid pressure fluctuations inside the bubbling bed of the reactor. These pressure transducers were placed both vertically and horizontally into the reactor. From these measurements it was found that the vertical pressure fluctuation took place at the same time at different levels of the bed. Also the same fluctuation could be seen under the air distributor. The horizontal pressure fluctuation was found to vary both by place and time. At the bottom part of the bed the highest pressure peaks was found at centre of the bed. Most of the time there was a pressure gradient the highest pressure being in the centre of the bed. This gradient creates horizontal flow of gases from middle to the sides. The velocity of this flow varies with the size of the pressure gradient. The opposite effect can be found in the upper part of the bed. The highest pressure was no more in the middle part of the bed. Instead, it was found to be between the centre of the bed and left and right walls. The pressure was low at the walls but also rather low at the middle of the bed. There must be flow towards the walls and to the centre axis. These pressure fluctuations can provide an explanation for the well-known “wandering plume” effect. They can also give a tool to better describe the mixing inside a bubbling fluidized bed. This kind of tool is needed when biomass combustion is modelled in bubbling fluidized bed.

Effects of operating conditions on longitudinal solids mixing in a circulating fluidized bed riser

AIChE Journal ◽  
1991 ◽  
Vol 37 (10) ◽  
pp. 1450-1458 ◽  
Author(s):  
M. J. Rhodes ◽  
S. Zhou ◽  
T. Hirama ◽  
H. Cheng
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Operating Conditions ◽  
Solids Mixing

Cold Flow Model Study on a Dual Circulating Fluidized Bed (DCFB) System for Chemical Looping Processes

2009 ◽  
Vol 32 (3) ◽  
pp. 418-424 ◽  
Author(s):  
T. Pröll ◽  
K. Rupanovits ◽  
P. Kolbitsch ◽  
J. Bolhàr-Nordenkampf ◽  
H. Hofbauer
Keyword(s):  
Fluidized Bed ◽  
Flow Model ◽  
Circulating Fluidized Bed ◽  
Chemical Looping ◽  
Cold Flow ◽  
Model Study
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