Solids Flow Pattern in the Bottom Zone of a Rectangular Cross-Section Circulating Fluidized Bed

2003 ◽  
Author(s):  
Hong-Shun Li ◽  
Yi-Jun Wang ◽  
Shi-Ping Jin
Keyword(s):  
Flow Pattern ◽  
Fluidized Bed ◽  
Cross Section ◽  
Quartz Sand ◽  
Circulating Fluidized Bed ◽  
Rectangular Cross Section ◽  
Temperature Response ◽  
Cold Model ◽  
Hot Particles ◽  
Bottom Zone

Solids flow pattern in the bottom zone of a rectangular cross-section CFB was investigated by using hot particles as the tracer. The experiments were carried out in a cold model circulating fluidized bed. The riser has an inner cross-section of 0.3 m by 0.5 m and a height of 5.8 m. The solids were returned into the riser at a height of 0.75 m above the air distributor within an angle of about 40 degree. Quartz sand was used as the bed material. The hot particles were also quartz sand but with a little smaller size. Specially designed miniature electrically heating devices were installed flush with the inner bed wall or inside the bed. At each run, about 10–15 cm3 hot particles were slowly pulled into the bed. The temperature response around the device was measured with four copper-constantan thermocouples. Based on the experimental results, a 3-D core-annulus model describing the solids flow pattern in the bottom zone of the CFB riser is proposed.

Solids mixing in the bottom zone of a circulating fluidized bed

2001 ◽  
Vol 120 (1-2) ◽  
pp. 21-33 ◽  
Author(s):  
Philipp Schlichthaerle ◽  
Joachim Werther
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Bottom Zone ◽  
Solids Mixing

Combustion Behavior and SO2, NOx Emissions of an Anthracite Coal in a Circulating Fluidized Bed

2005 ◽  
Author(s):  
Leming Cheng ◽  
Zhongyang Luo ◽  
Zhenglun Shi ◽  
Haixiao Zheng ◽  
Qinghui Wang ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Cross Section ◽  
Circulating Fluidized Bed ◽  
Nox Emissions ◽  
So2 Emission ◽  
Combustion Behavior ◽  
Excess Air ◽  
Anthracite Coal ◽  
Bed Temperature ◽  
Experimental Researches

Combustion behavior and SO2, NOx emissions of anthracite coal in a circulating fluidized bed are reported in this paper. Experimental researches were done on a 1 MWt circulating fluidized bed facility with a 0.31 m × 0.31 m cross section and 11.2 m height combustor. The anthracite coal with 6.28% volatile and 3.76% sulfur content burns steadily during the test. The bed was operated under different temperature, Ca/S ratio and excess air. A limestone containing 75% CaCO3 and 15% MgCO3 was used as the sulfur sorbent. Results show that the SO2 emission varies with operating bed temperature and more than 90% sulfur capture efficiency can be reached while Ca/S is about 3. With Rosemount Analytical NGA2000, N2O, NO and NO2 were also measured in the test. It was found the majority content of NOx was NO and the least was NO2. Those NOx emissions change highly with the excess air number.

The Performance of a Loop Seal in a CFB Boiler

2006 ◽  
Vol 128 (2) ◽  
pp. 135-142 ◽  
Author(s):  
Andreas Johansson ◽  
Filip Johnsson ◽  
Bengt-Åke Andersson
Keyword(s):  
Heat Transfer ◽  
Flow Pattern ◽  
Fluidized Bed ◽  
Scaling Laws ◽  
Circulating Fluidized Bed ◽  
Vertical Direction ◽  
Scale Model ◽  
Corrosive Environment ◽  
Cfb Boiler ◽  
Load Conditions

High in-bed heat transfer and low corrosive environment imply that the loop seal of a circulating fluidized bed (CFB) boiler is an advantageous location for superheaters. In order to increase the knowledge on the flow pattern and the heat transfer distribution to the tubes within a loop seal, measurements were performed in the loop seal of a 30MW CFB boiler as well as in a 1∕3 scaled-down seal operated according to simplified scaling laws. The scale model measurements show that the solids recirculation flux can be maintained with a substantial decrease of the fluidization flow in the seal compared to that currently used at full load conditions. It was also possible to significantly decrease the fraction of the bottom of the seal that was fluidized without affecting the solids flux through the seal. A gradient in the solids flow were detected in the vertical direction.

Fluidization of sawdust in a cold model circulating fluidized bed: Experimental study

2011 ◽  
Vol 167 (1) ◽  
pp. 335-341 ◽  
Author(s):  
Qi Miao ◽  
Chu Wang ◽  
Chuangzhi Wu ◽  
Xiuli Yin ◽  
Jesse Zhu
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Cold Model

scholarly journals The effect of collar width ratio on the flow pattern around oblong pier in bend

2021 ◽  
Author(s):  
Danesh Dehghan ◽  
Mohammad Vaghefi ◽  
Masoud Ghodsian
Keyword(s):  
Flow Pattern ◽  
Cross Section ◽  
Rectangular Cross Section ◽  
Width Ratio ◽  
Curvature Radius ◽  
Reynolds Stresses ◽  
Clear Water ◽  
Flow Conditions ◽  
Channel Bend ◽  
Oblong Pier

Abstract In this paper, the effect of collar width ratio on the flow pattern around an oblong pier in a 180-degree channel bend was experimentally studied. This channel has a rectangular cross section. It is 1 m in width and 0.7 m in height. The upstream and downstream paths are respectively 6.5 and 5 m long. The ratio of the bend's central curvature radius to the channel width is 2; hence, it qualifies as a sharp bend. Experiments were carried out under clear water approach flow conditions. The results showed that the presence of collars around an oblong pier creates vortices in the opposite direction of the longitudinal flow, causes the distortion and disturbance of the streamlines toward the pier downstream, and decreases downflow strength in front of the pier nose. Furthermore, doubling the collar width results in 0.68 and 0.93 times the vorticity and the power of the secondary flow on the pier upstream, respectively. It also reduced the maximum values of the Reynolds stresses perpendicular to the y-plane in x direction and perpendicular to the z-plane in y direction by respectively 45 and 60%, and increased the Reynolds stress perpendicular to the z-plane in x direction by 25%.

Application of an Expert System to the Design of Furnace of a Circulating Fluidized Bed Boiler

1994 ◽  
Vol 116 (3) ◽  
pp. 462-467 ◽  
Author(s):  
P. Basu ◽  
S. Mitra
Keyword(s):  
Artificial Intelligence ◽  
Decision Making ◽  
Expert System ◽  
Fluidized Bed ◽  
Cross Section ◽  
Circulating Fluidized Bed ◽  
New Technology ◽  
Fluidized Bed Combustion ◽  
The Subject ◽  
Circulating Fluidized Bed Combustion

The design of a boiler using a new technology, i.e., circulating fluidized bed combustion, requires a considerable amount of expertise, which is a combination of experience, knowledge of the subject, and intuition. Boiler vendors, who are required to prepare a large number of proposals, rely heavily on the the skill and judgment of their senior (expert) designers. An artificial intelligence based expert system can greatly simplify this task. This system can assist expert designers to store their experience and decision-making skill through the code of a computer program, which remains intact and ready to apply their skill uniformly and rapidly to all designs when required. This may allow novice designers to carry out routine proposal designs, freeing the experts to improve current designs. The present paper gives an illustration of the use of expert systems to the design of only one aspect of the furnace, which is furnace cross section. It shows that in addition to the standard method of determining the furnace area from the fluidization, the design can take advantage of previous experience, which lists grate heat release rate and other relevant parameters. The expert system also modifies the calculated value to meet different concerns of the boiler purchaser and/or his consultants. Finally the expert develops a compromise of different considerations and requirements with importance attached to them. The paper also shows how the design will change when the importance attached to a particular constraint is relaxed.

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