Effect of bed temperature on bubble size and bubble rising velocity in a semi-cylindrical slugging fluidized bed.

1990 ◽  
Vol 23 (6) ◽  
pp. 765-767 ◽  
Author(s):  
Yasuo Hatate ◽  
Kazuya Ijichi ◽  
Yoshimitsu Uemura ◽  
Mitsunobu Migita ◽  
Desmond F. King
Keyword(s):  
Fluidized Bed ◽  
Bubble Size ◽  
Bed Temperature ◽  
Bubble Rising ◽  
Bubble Rising Velocity

Experimental Measurement on Bubble Parameters During Fluidized Bed Scaling

2005 ◽  
Author(s):  
Xin Wang ◽  
Junfu Lu ◽  
Jiansheng Zhang ◽  
Hairui Yang ◽  
Hai Zhang ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Bubble Diameter ◽  
Behavior Prediction ◽  
Analysis Method ◽  
Cold Model ◽  
Scaling Method ◽  
Bubble Rising ◽  
Bubble Rising Velocity

An experimental verification is reported on the bubble parameter similarity during fluidized bed scaling. Two bubbling fluidized beds were designed according to Horio’s scaling method, and bubble size and mean bubble rising velocity were measured and compared. It can be concluded from the results that with the increment of u/umf, the similarity between two beds increases with respect to the bubble diameter and rising velocity. The analysis of the experimental data confirms the applicability of Horio’s method on bubble fluidized bed. When given dynamic behavior prediction of a real boiler is desired, the Horio’s law is valid to establish a cold model and the analysis method introduced in the present paper can be used.

The Local Heat Balance in a Stationary Fluidized-Bed Furnace Burning Biomass Fuels

2003 ◽  
Author(s):  
Fredrik Niklasson ◽  
Filip Johnsson
Keyword(s):  
Fluidized Bed ◽  
Combustion Rate ◽  
Heat Balance ◽  
Circulating Fluidized Bed ◽  
Local Heat ◽  
Splash Zone ◽  
Two Phase ◽  
Bed Temperature ◽  
Temperature Constant ◽  
The Vertical Distribution

This work investigates the influence of biomass fuel properties on the local heat balance in a commercial-scale fluidized bed furnace. Experiments with different wood based fuels were performed in the Chalmers 12 MWth circulating fluidized bed boiler, temporarily modified to run under stationary conditions. A two-phase flow model of the bed and splash zone is applied, where the combustion rate in the bed is estimated by global kinetic expressions, limited by gas exchange between oxygen-rich bubbles and a fuel-rich emulsion phase. The outflow of bubbles from the bed is treated as “ghost bubbles” in the splash zone, where the combustion rate is determined from turbulent properties. It is found that a large amount of heat is required for the fuel and air to reach the temperature of the bed, in which the heat from combustion is limited by a low char content of the fuel. This implies that a substantial fraction of the heat from combustion of volatiles in the splash zone has to be transferred back to the bed to keep the bed temperature constant. It is concluded that the moisture content of the fuel does not considerably alter the vertical distribution of heat emitted, as long as the bed temperature is kept constant by means of flue gas recycling.

The Pyrocarbon Deposition Techniques of Mechanical Heart Valve Prostheses

2011 ◽  
Vol 464 ◽  
pp. 749-752 ◽  
Author(s):  
Jian Hui Zhang ◽  
Xin Chen
Keyword(s):  
Fluidized Bed ◽  
Heart Valve ◽  
Gas Flow ◽  
Mechanical Heart Valve ◽  
Carbon Matrix ◽  
Artificial Heart Valve ◽  
Bed Temperature ◽  
Wide Range ◽  
Isotropic Carbon ◽  
Deposition Conditions

The structure and property of pyrocarbon varies widely with different deposition conditions. The isotropic carbon which can only been deposited in the bed of fluidized particles is very important in biomedical fields, for instance, it is often used as the coating of artificial heart valve components. The deposition of isotropic pyrocarbon containing silicon is experimented in fluidized bed over a wide range of deposition conditions. The results show that bed temperature influences strongly average coating rate, coating density, silicon content and coating micro-hardness. Propane concentration has a much effect on coating density, carbon matrix density and isotropic characteristics. Total gas flow rate and inlet dimension of fluidized bed affect the formation of fluidized bed.

scholarly journals Heat transfer to a moving wire immersed in a gas fluidized bed furnace

2021 ◽  
Author(s):  
Antonio Tannas
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Steel Wire ◽  
Transfer Rates ◽  
New Correlation ◽  
Bed Temperature ◽  
Molten Lead ◽  
The Difference ◽  
Considerable Work ◽  
Work Done

In order to replace hazardous molten lead baths in the heat treatment of carbon steel wire with environmentally friendly fluidized bed furnaces a better understanding is needed of their heat transfer rates. There has been considerable work done in examining heat transfer rates to large cylinders immersed in fluidized beds, and some on wire sized ones as well, but all previous studies have been conducted on static cylinders. In order to gain a deeper understanding of heat transfer rates to a moving wire immersed in a fluidized bed furnace an apparatus has been constructed to move a wire through a fluidized bed. The heat transfer rates were calculated using the difference in inlet and outlet temperatures, wire speed and the bed temperature. As predicted, correlations for static wire were found to under-predict heat transfer rates at higher wire speeds, so a new correlation was developed by modifying an existing one.

Investigation of single bubble rising velocity in LBE by transparent liquids similarity experiments

2018 ◽  
Vol 108 ◽  
pp. 204-213 ◽  
Author(s):  
Chaodong Zhang ◽  
Danna Zhou ◽  
Rongyuan Sa ◽  
Qingsheng Wu
Keyword(s):  
Single Bubble ◽  
Bubble Rising ◽  
Bubble Rising Velocity

Identification of Circulating Fluidized Bed Boiler Bed Temperature Based on Hyper-Plane-Shaped Fuzzy C-Regression Model

2020 ◽  
Vol 19 (04) ◽  
pp. 2050029
Author(s):  
Jianzhong Shi
Keyword(s):  
Regression Model ◽  
Fluidized Bed ◽  
Membership Function ◽  
Clustering Algorithm ◽  
Circulating Fluidized Bed ◽  
Fuzzy Model ◽  
Identification Algorithm ◽  
Identification Process ◽  
Bed Temperature ◽  
Hyper Plane

Bed temperature in dense-phase zone is the key parameter of circulating fluidized bed (CFB) boiler for stable combustion and economic operation. It is difficult to establish an accurate bed temperature model as the complexity of circulating fluidized bed combustion system. T-S fuzzy model was widely applied in the system identification for it can approximate complex nonlinear system with high accuracy. Fuzzy c-regression model (FCRM) clustering based on hyper-plane-shaped distance has the advantages in describing T-S fuzzy model, and Gaussian function was adapted in antecedent membership function of T-S fuzzy model. However, Gaussian fuzzy membership function was more suitable for clustering algorithm using point to point distance, such as fuzzy c-means (FCM). In this paper, a hyper-plane-shaped FCRM clustering algorithm for T-S fuzzy model identification algorithm is proposed. The antecedent membership function of proposed identification algorithm is defined by a hyper-plane-shaped membership function and an improved fuzzy partition method is applied. To illustrate the efficiency of the proposed identification algorithm, the algorithm is applied in four nonlinear systems which shows higher identification accuracy and simplified identification process. At last, the algorithm is used in a circulating fluidized bed boiler bed temperature identification process, and gets better identification result.

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