scholarly journals Analysis of model parameters affecting the pressure profile in a circulating fluidized bed

AIChE Journal ◽  
2011 ◽  
Vol 58 (2) ◽  
pp. 427-439 ◽  
Author(s):  
Sofiane Benyahia
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pressure Profile ◽  
Model Parameters

Three-Dimensional Modeling and Model Validation of Circulating Fluidized Bed Combustion

2003 ◽  
Author(s):  
Kari Myo¨ha¨nen ◽  
Timo Hyppa¨nen ◽  
Jouni Miettinen ◽  
Riku Parkkonen
Keyword(s):  
Heat Flux ◽  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Hot Water ◽  
Combustion Model ◽  
Process Conditions ◽  
Model Parameters

This paper presents a three-dimensional, steady state combustion model for a circulating fluidized bed (CFB) furnace and several calculation cases which have been used for the validation of the model. The model includes essential submodels to describe the complex combustion process in a circulating fluidized bed boiler. These include the hydrodynamics of the bed, devolatilization of fuel, combustion of char, combustion of hydrocarbons, carbon monoxide and hydrogen, calcination and sulfation, fragmentation and attrition of solids, heat transfer, overall mass balance of the furnace, and three-dimensional balance equations based on the finite volume method. The code was initially developed in 1989, and it has been updated and improved over the years as new methods and new information have become available. The model is used for increasing process knowledge and for studying such phenomena inside the furnace which are often difficult or impossible to study by direct measurements. The knowledge obtained is then applied to optimize boiler design and process performance in terms of efficiency, economy and environmental issues. Reliable experiments and measurements in commercial boilers are used for the validation of the model and for tuning the model parameters. For the validation of a three-dimensional model, extensive profile measurements of the various parts of the furnace are required. This paper presents validation studies for an 80 MWth hot water boiler burning bituminous coal and for a 235 MWe subcritical boiler burning lignite. The measurements with these units included profile measurements of heat flux, pressure, temperature and gas composition under different process conditions. The model was tuned according to the measurements and used for the prediction of the heat flux profile of a large scale supercritical CFB boiler.

Hydrodynamics of Double-Dipleg Circulating Fluidized Beds for Waste Incineration

2003 ◽  
Author(s):  
Xiaoyin Yun ◽  
Weigang Lin ◽  
Shaohua Wu
Keyword(s):  
Fluidized Bed ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Circulating Fluidized Bed ◽  
Waste Incineration ◽  
Pressure Profile ◽  
Gas Velocity ◽  
New Type ◽  
Superficial Gas Velocity

In order to solve the problems of high temperature chlorine induced corrosion and the emission of dioxins, a new type of double-dipleg circulating fluidized bed incinerator is under development at the Institute of Process Engineering, Chinese Academy of Sciences. Understanding the hydrodynamics of such new type of CFB incinerator are of crucial importance for successful design and operation of the system. Experiments have been carried out in a lab-scale double-dipleg circulating fluidized bed to study the hydrodynamics of such system. The investigation is focused on the pressure profile in the loop and residence time distribution of particles with different sizes and densities in the secondary dipleg. The results show that the pressure profile in such system is similar to that in the conventional CFB. The residence time distribution (RTD) function of particles in the second dipleg varies with particle recirculating rate, superficial gas velocity and the characteristics of the particles, such as density and size. The mean residence time of particles decreases sharply with an increase of the particle re-circulating rate and slightly decreases as the superficial gas velocity increases. It appears that the density of particle has a stronger influence on the residence time than the particle size. The lighter particles have a shorter residence time. The residence time distribution function of the particles is described by a tank-in-series model. The implication of the results to the design and operation of the double-dipleg circulating fluidized bed incinerator are discussed.

Real Time Implementation of Standpipe Model for Solids Flow in Circulating Fluidized Bed

2018 ◽  
Author(s):  
Rupendranath Panday ◽  
Lawrence Shadle ◽  
Ronald Breault
Keyword(s):  
Real Time ◽  
Fluidized Bed ◽  
Velocity Measurement ◽  
Circulating Fluidized Bed ◽  
Model Development ◽  
Stable Process ◽  
Nonlinear Least Squares ◽  
Pressure Profile ◽  
Optimization Techniques ◽  
Time Model

Increased accuracy of solids flow meters can be achieved with sensor fusion; the combination of solids velocity measurement with other process sensors to define the process state of the solids while they flow. In a circulating fluidized bed aeration flow, temperature measurements, and pressure differentials are routinely measured to ensure stable process operations. These process measurements were used as input to real-time model of the standpipe where the velocity measurement was taken to determine the actual solids bed density. The model development and implementation are described with the objective of updating the measured flows continuously in real time. Real time optimization techniques use the pressure measurements for inferring voidage and apply the inferred values to estimate the pressure profile and aeration split. In essence, the approach becomes solving nonlinear least squares problem and closure of mass balance of gas in real time.

Modeling of Solid Fuel Combustion in Furnaces with a Circulating Fluidized Bed

2008 ◽  
Vol 39 (1) ◽  
pp. 65-78
Author(s):  
Yu. S. Teplitskii ◽  
V. A. Borodulya ◽  
V. I. Kovenskii ◽  
E. P. Nogotov
Keyword(s):  
Fluidized Bed ◽  
Solid Fuel ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Solid Fuel Combustion
Sign in / Sign up

Export Citation Format

Share Document