Effect of Novel Swirling Perforated Distributor on Fluid Dynamic Characteristics of Circulating Fluidized Bed Riser

2016 ◽  
Author(s):  
M. G. Kalola ◽  
Mahesh Dasar ◽  
K. P. Shete ◽  
R. S. Patil
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Turbulence Modeling ◽  
Circulating Fluidized Bed ◽  
Dead Zone ◽  
Cfd Simulations ◽  
Suspension Density ◽  
Wide Range ◽  
The Dead ◽  
Distributor Plate

The present work is associated with Circulating Fluidized Bed (CFB) technology, related to the energy sector. The applications of CFB technology span across wide range of areas i.e. boiler, gasifier, combustor, dryer, etc. In the present paper, CFD simulations using ANSYS-Fluent 14.5 were performed to study the effect of novel swirling perforated distributor on fluid dynamics characteristics like pressure drop along the riser and distributor, suspension density variations along the riser of the Circulating Fluidized Bed (CFB). The simulation results were also used to compare qualitatively and quantitatively the dead-zone formations in the four corners of riser just above the distributor plate for swirl and normal distributor plates. The riser alongwith distributor was modeled using Pro-E 5.0, and it was meshed in ICEM CFD 14.5. Post processing simulations were performed using Fluent 14.5. 3D CFD simulations were performed on the CFB riser of cross section 0.15 m × 0.15 m and height 2.85 m. RNG k-ε model was used for turbulence modeling. Eulerian model with Syamlal-O’Brien phase interaction scheme was used to simulate the two phase flow (air + sand mixture flow). RNG k-ε model was used for turbulence modeling of the flow inside the riser. The RNG turbulence model has a calculation for effective viscosity. Modeling and simulations were performed for normal perforated distributor plate and results obtained were compared with available experimental data. In this way, after validation of computational results, further CFD simulations were performed for novel geometry of swirl distributor plate. It is observed that suspension density (particles’ concentration) was more in the middle and upper region of the riser in case of swirl distributor plate. However, pressure drop across the distributor plate increased in the case of novel swirl distributor plate. The objective of significant reduction in the dead-zone formation just above the normal distributor plate was achieved through novel swirl distributor, which in-turn is expected to increase particles’ participation in combustion which takes place in oxygen rich middle portion of CFB riser and subsequently increases heat transfer rate in the CFB riser.

scholarly journals Experimental and computational evaluation of a gas-solid suspension density distribution under circulating fluidized bed conditions

2021 ◽  
Vol 2130 (1) ◽  
pp. 012025
Author(s):  
P Mirek
Keyword(s):  
Density Distribution ◽  
Combustion Chamber ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Multiphase Model ◽  
Thermal Loads ◽  
Bottom Part ◽  
Boiler Load ◽  
Suspension Density ◽  
Eulerian Multiphase Model

Abstract The paper presents the results of operational measurements of the suspension density distribution in the 966 MWth supercritical Circulating Fluidized Bed boiler. The tests were carried out for four different unit thermal loads, i.e. 40, 60, 80, and 100% MCR. The conducted operational measurements showed that the suspension density distribution of the particulate material in the combustion chamber of the CFB boiler has the form of an exponential curve with maximum values occurring in the bottom part of the furnace. On the basis of the operational data, an attempt was made to reflect the suspension density distribution in the combustion chamber of the boiler using the ANSYS CFD software. The calculations were carried out using the Eulerian multiphase model in an unsteady state condition. As revealed by the simulations, the Eulerian multiphase model allows for a quantitative representation of the suspension density distribution of the granular material only for the maximum boiler load. For other thermal loads, quantitative representation of experimental distributions of suspension density using the Eulerian method is possible except for the dense region.

scholarly journals Hydrodynamic experiments on a small-scale circulating fluidized bed reactor at elevated operating pressure, and under an O2/CO2 environment

2017 ◽  
Vol 21 (2) ◽  
pp. 1093-1104 ◽  
Author(s):  
Yerbol Sarbassov ◽  
Azd Zayoud ◽  
Pinakeswar Mahanta ◽  
Sai Gu ◽  
Panneerselvam Ranganathan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Atmospheric Pressure ◽  
Circulating Fluidized Bed ◽  
Elevated Pressure ◽  
Small Scale ◽  
Operating Pressure ◽  
Hydrodynamic Parameters ◽  
Hydrodynamic Experiments ◽  
Promising Development

Pressurized circulating fluidized bed technology is a potentially promising development for clean coal technologies. The current work explores the hydrodynamics of a small-scale circulating fluidized bed at elevated operating pressures ranging from 0.10 to 0.25 MPa. The initial experiments were performed at atmospheric pressure with air and O2/CO2 environments as the fluidization gas to simulate the hydrodynamics in a circulating fluidized bed. A comparison between the effects of air and O2/CO2 mixtures on the hydrodynamics was outlined in this paper for particles of 160 ?m diameter. A small but distinct effect on axial void-age was observed due to the change in gas density in the dense zone of the bed at lower gas velocity, while only minimal differences were noticed at higher gas velocities. The hydrodynamic parameters such as pressure drop and axial voidage profile along the height were reported at two different bed inventories (0.5 and 0.75 kg) for three mean particle sizes of 160, 302, and 427 ?m and three superficial gas velocities. It was observed that the operating pressure had a significant effect on the hydrodynamic parameters of bed pressure drop and axial bed void-age profiles. The effect of solids loading resulted in an exponential change in pressure drop profile at atmospheric pressure as well as at elevated pressure. The experimental results on hydrodynamic parameters are in reasonable agreement with published observations in the literature.

scholarly journals Combustion adjustment and operation optimiztion of a 240 t/h circulating fluidized bed boiler

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2689-2698
Author(s):  
Xuemin Liu ◽  
Songsong Zhang ◽  
Yongqiang Chang ◽  
Zhongwei Wang ◽  
Guoli Qi
Keyword(s):  
Fly Ash ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flue Gas ◽  
Circulating Fluidized Bed ◽  
Air Flow ◽  
Nox Emission ◽  
Unburned Carbon ◽  
Boiler Efficiency ◽  
Co Concentration

The influence of main operating parameters on boiler performance was studied, such as bed pressure drop, primary air-flow and secondary air-flow. Combustion adjustment tests were carried out on a circulating fluidized bed boiler with rated capacity of 240 t/h. From the test results, it can be seen that the loss due to exit flue gas is the largest heat loss of the boiler, accounting for more than 70% of the total heat losses. For coal fired boilers, compared with the loss due to unburned solids, the loss due to unburned gases is quite small. The unburned carbon con-tent in bottom ash is far lower than the value in fly ash. The trend of CO concentration in the exit flue gas is similar to that of the unburned carbon content in fly ash. To achieve higher boiler efficiency, the bed pressure drop is suggested to be maintained in about 8.5-9.0 kPa and the oxygen content in exit flue gas around 4%. The NOx emission concentration usually presents a negative correlation with CO concentration in exit flue gas. Through combustion adjustment and operation optimization, the NOx emission can be decreased by about 30% without affecting the boiler efficiency.

Attrition Behavior of Coal Ash Under Circulating Fluidized Bed Combustion Conditions

2003 ◽  
Author(s):  
Franz Winter ◽  
Xin Liu
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Coal Ash ◽  
Operating Conditions ◽  
Laboratory Scale ◽  
Silica Sand ◽  
Electrical Heating ◽  
Fluidized Bed Combustion ◽  
Bed Temperature ◽  
Wide Range

The attrition behavior of ash produced from two bituminous and one anthracite coal was studied under laboratory-scale circulating fluidized bed combustor (CFBC) conditions. After the ash was produced in the oven, the ash sample with a size range from 0.1 to 1 mm was fed into the hot CFBC, which was heated by electrical heating shells and fluidized by air. The laboratory-scale CFBC was operated with using fine silica sand (40 to 80 μm) as bed material. After a certain time the operation was stopped, all particles were collected and sieving analysis was performed to obtain the actual particle size distribution (PSD) of the coal ash. The operating conditions were changed in a wide range, i.e. the bed temperature from 600 to 850°C, the fluidizing velocity from 1.2 to 2 m/s, the residence time from 60 to 120 min and the design of the cyclone. The effects of operating conditions and coal type were studied and their relative importance is discussed. Elemental analysis of the coal ashes showed that Si and Ca may play an important role during attrition.

Pressure drop of liquid–solid two-phase flow in a down-flow circulating fluidized bed

2020 ◽  
Vol 375 ◽  
pp. 136-145
Author(s):  
Siyao Lv ◽  
Feng Jiang ◽  
Guopeng Qi ◽  
Xiaoling Chen ◽  
Xiulun Li
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Two Phase Flow ◽  
Circulating Fluidized Bed ◽  
Phase Flow ◽  
Two Phase
Sign in / Sign up

Export Citation Format

Share Document