Neural network modeling and control of cold flow circulating fluidized bed
10
Citation
6
Reference
10
Related Paper
Citation Trend
Abstract:
Circulating fluidized beds (CFB) are a relatively new method of forcing chemical reactions to occur in chemical and petroleum industries. Compared with conventional fluidized beds, CFB have many advantages including better interfacial contacting and reduced back mixing. The recycle nature of CFB allows for a better process, but also makes modeling and understanding it many more times difficult. The plant under consideration is a cold-flow circulating fluidized bed (CF-CFB), meaning there is no combustion component in it. In the absence of conventional means to derive a reliable model, we have devised a model of the CFB using neural networks (NN), which have the ability to characterize such complex systems. This stems from their ability to approximate arbitrary nonlinear mappings. The main objective is to train a NN model and controller to simulate and control the CFB operation. It has been shown that a NN can be used effectively for the identification and control of nonlinear dynamical processes. Results are presented.Keywords:
Fluidized bed combustion
Forcing (mathematics)
Fluidization
This paper deals with the influence of the structure and shape of the vcssel and pipe line on the fluidization quality of fluidized bed as it is investigated by the author.The quality of fluidized bed was measured by means of non-uniformity index (fluidization index) proposed by W.W. Shuster. As the result, it was found out that the arrangements of the holes in the bottom plate of the bed and the length of the pipe line had a considerable influence on the quality of fluidization, and that divergent type reaction vessels had better quality than ordinary cylindrical ones.
Fluidization
Cite
Citations (2)
Low-frequency flow pulsations were utilized to improve the hydrodynamics of the fluidized bed of hydrophilic ultrafine nanosilica powder with strong agglomeration behavior. A gradual fluidization of unassisted fluidized bed through stepwise velocity change was carried out over a wide range of velocities followed by a gradual defluidization process. Bed dynamics in different regions of the fluidized bed were carefully monitored using fast and sensitive pressure transducers. Next, 0.05-Hz square-wave flow pulsation was introduced, and the fluidization behavior of the pulsed fluidized bed was rigorously characterized to delineate its effect on the bed hydrodynamics by comparing it with one of the unassisted fluidized bed. Flow pulsations caused a substantial decrease in minimum fluidization velocity and effective agglomerate diameter. The frequencies and amplitudes of various events in different fluidized bed regions were determined by performing frequency domain analysis on real-time bed transient data. The pulsations and their effects promoted deagglomeration and improved homogeneity of the pulsed fluidized bed.
Fluidization
Agglomerate
Cite
Citations (16)
Fluidization
Particle (ecology)
Particle density
Density ratio
Cite
Citations (31)
Fluidization
Iron ore
Electric current
Cite
Citations (9)
The fluidization behavior of Geldart D particles in the deep fluidized bed was systematically investigated through the pressure fluctuation measurement, high-speed camera, and intrusive acoustic emission (AE) detection method. Results displayed that, both in the three-dimensional (3D) fluidized bed and the pseudo-2D fluidized bed, with the increase of gas velocity, the deep fluidized bed of Geldart D particles would experience three different fluidization regimes: the slow bubble regime, slugging regime, and the turbulent regime. The consistency of regimes indicated the rationality of studying the fluidization behavior in the pseudo-2D fluidized bed. In addition, in the slow bubble regime, due to the wall effect, stratified fluidization was observed in the pseudo-2D fluidized bed but not in the 3D fluidized bed. In the turbulent regime, the gas bypassing appeared in the center of both pseudo-2D and 3D fluidized beds.
Fluidization
Slugging
Cite
Citations (0)
In (bubbling) fluidized-bed combustion and gasification of biomass, several potential problems are associated with the inorganic components of the fuel. A major problem area is de-fluidization due to bed agglomeration. The most common found process leading to de-fluidization in commercial-scale installations is “coating-induced” agglomeration. During reactor operation, a coating is formed on the surface of bed material grains and at certain critical conditions (e.g., coating thickness or temperature) sintering of the coatings initiates the agglomeration. In an experimental approach, this work describes a fundamental study on the mechanisms of de-fluidization. For the studied process of bed de-fluidization due to sintering of grain-coating layers, it was found that the onset of the process depends on: a) a critical coating thickness, b) on the fluidization velocity when it is below approx. four times the minimum fluidization velocity and c) on the viscosity (stickiness) of the outside of the grains (coating).
Fluidization
Cite
Citations (44)
The fluidization characteristics of several kinds of wastes were measured in a cold fluidized bed rig to develop a combustion model for municipal solid wastes in fluidized bed. The results show that the bed materials cause consistent fluidization of various kinds of wastes moving up and down inside the dense zone of the fluidized bed. However, the wastes can restraint fluidization of the bed materials. Polyethylene particles were chosen to represent the waste particles. A model describing the interaction between the plastic particles and the bed materials can be used to compute the acceleration of a plastic particle at any given bed material velocity. The movements of the plastic particles inside the fluidized bed can then be calculated once the bed material motion is defined.
Fluidization
Fluidized bed combustion
Particle (ecology)
Cite
Citations (1)
Large amounts of Chinese herbal medicine wastes (CHMW) are produced in the process of processing and manufacturing traditional Chinese crude medicines. For CHMW, gasification in fluidized bed is a promising option. But, it is the difficult to fluidize CHMW particles alone in fluidized bed gasifier, especially for various size and shape of CHMW particles. It is very common to fluidize these kinds of biomass particles with sand, gives better defined fluidization behavior and a more reliable scale-up. However, not much is known about fluidization behavior of CHMW particles in fluidized bed. Therefore, a fluidized bed and its air distribution were designed and set up, the experimental study on fluidization characteristic of CHMW was done in the fluidize bed. Minimum fluidization velocity and the effect of bed height of CHMW/quartz sand mixtures on fluidization properties in air have been experimentally determined. The results showed that good fluidized could achieve with the additional of quartz sand. The results will be in favorite design and operation of CHMW gasification in fluidized bed.
Fluidization
Cite
Citations (4)
Fluidization
Particle (ecology)
Cite
Citations (7)
Acoustic fluidized bed is formed by introducing a sound field into a fluidized bed filled with particles as bed matrix.Acoustic field can reduce particle agglomerate size,and dramatically improve the fluidization quality of particles.The principle of acoustic fluidized bed and the progress of basic research and application of acoustic fluidized bed are presented.The research of acoustic fluidized bed including hydrodynamics characteristics,particle characteristics,sound field parameters,fluidization model,particle agglomeration and mechanism of fluidization is reviewed.The existing problems and the development of acoustic fluidized bed technology are proposed.
Fluidization
Agglomerate
Particle (ecology)
Cite
Citations (2)