scholarly journals State-of-the-art review and report on critical aspects and scale-up considerations in the design of fluidized-bed reactors. Final report on Phase 1

1980 ◽  
Author(s):  
Keyword(s):  
Fluidized Bed ◽  
State Of The Art ◽  
Phase 1 ◽  
Scale Up ◽  
Fluidized Bed Reactors ◽  
Final Report ◽  
Critical Aspects

Development of a Continuous Fluidized Bed Reactor for Thermochemical Energy Storage Application

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Manuel Wuerth ◽  
Moritz Becker ◽  
Peter Ostermeier ◽  
Stephan Gleis ◽  
Hartmut Spliethoff
Keyword(s):  
Energy Storage ◽  
Fluidized Bed ◽  
State Of The Art ◽  
Scale Up ◽  
Fixed Bed ◽  
Fluidized Bed Reactor ◽  
Fluidized Bed Reactors ◽  
Heat Of Reaction ◽  
Reaction Systems

Thermochemical energy storage (TCES) represents one of the most promising energy storage technologies, currently investigated. It uses the heat of reaction of reversible reaction systems and stands out due to the high energy density of its storage materials combined with the possibility of long-term storage with little to no heat losses. Gas–solid reactions, in particular the reaction systems CaCO3/CaO, CaO/Ca(OH)2 and MgO/Mg(OH)2 are of key interest in current research. Until now, fixed bed reactors are the state of the art for TCES systems. However, fluidized bed reactors offer significant advantages for scale-up of the system: the improved heat and mass transfer allows for higher charging/discharging power, whereas the favorable, continuous operation mode enables a decoupling of storage power and capacity. Even though gas–solid fluidized beds are being deployed for wide range of industrial operations, the fluidization of cohesive materials, such as the aforementioned metal oxides/hydroxides, still represents a sparsely investigated field. The consequent lack of knowledge of physical, chemical, and technical parameters of the processes on hand is currently a hindering aspect for a proper design and scale-up of fluidized bed reactors for MW applications of TCES. Therefore, the experimental research at Technical University of Munich (TUM) focuses on a comprehensive approach to address this problem. Preliminary experimental work has been carried out on a fixed bed reactor to cover the topic of chemical cycle stability of storage materials. In order to investigate the fluidization behavior of the bulk material, a fluidized bed cold model containing a heat flux probe and operating at atmospheric conditions has been deployed. The experimental results have identified the heat input and output as the most influential aspect for both the operation and a possible scale-up of such a TCES system. The decisive parameter for the heat input and output is the heat transfer coefficient between immersed heat exchangers and the fluidized bed. This coefficient strongly depends on the quality of fluidization, which in turn is directly related to the geometry of the gas distributor plate. At TUM, a state-of-the-art pilot fluidized bed reactor is being commissioned to further investigate the aforementioned aspects. This reactor possesses an overall volume of 100 L with the expanded bed volume taking up 30 L. Two radiation furnaces (64 kW) are used to heat the reactor. The heat of reaction of the exothermal hydration reaction is removed by water, evaporating in a cooling coil, immersed in the fluidized bed. Fluidization is being achieved with a mixture of steam and nitrogen at operating temperatures of up to 700 °C and operating pressures between −1 and 6 bar(g). The particle size is in the range of d50 = 20 μm. While initial experiments on this reactor focus on optimal operating and material parameters, the long-term goal is to establish correlations for model design and scale-up purposes.

scholarly journals Diffusion models and scale-up

2005 ◽  
Vol 9 (1) ◽  
pp. 43-72 ◽  
Author(s):  
Christo Boyadjiev
Keyword(s):  
Mass Transfer ◽  
Parameter Identification ◽  
Fluidized Bed ◽  
Scale Up ◽  
Catalytic Reactions ◽  
Fluidized Bed Reactors ◽  
Hierarchical Approach ◽  
Model Parameter ◽  
Transfer Processes ◽  
Three Phase

A model for transfer processes in column apparatuses has been done. The model may be modified for different apparatuses as columns with (or without) packet bed, two (or three) phase airlift reactors and fluidized bed reactors. The mass transfer is result of different volume reactions as a chemical, photochemical, biochemical or catalytic, reactions, or interphase. mass transfer. The using of the average velocities and concentration permit to solve the scale-up problems. A hierarchical approach for model parameter identification has been proposed.

Scale-up and biomass hold-up characteristics of biological fluidized bed reactors

1994 ◽  
Vol 29 (10-11) ◽  
pp. 353-360 ◽  
Author(s):  
I. Ozturk ◽  
M. Turan ◽  
A. H. Idris
Keyword(s):  
Fluidized Bed ◽  
Scale Up ◽  
Experimental Studies ◽  
Scaling Up ◽  
Pilot Scale ◽  
Fluidized Bed Reactors ◽  
Biofilm Thickness ◽  
Study Results ◽  
Scaling Down ◽  
Comprehensive Study

This paper presents a comprehensive study results on scale-up and biomass hold-up characteristics of biological fluidized bed reactors (BFBR). The overall objective of this study was to establish and test some basic design criteria for the scaling-up or scaling-down of anaerobic fluidized bed reactors. A 12.5 1 laboratory-scale fluidized bed was designed and constructed based on a geometrically similar 70 1 pilot scale fluidized bed and the process performances were compared. Biomass hold up characteristics of the BFBRs were also investigated during the experimental studies. A general expression was developed for predicting the biological fludized bed porosities. Using this expression, both the local and overall fluidized bed porosities could be predicted depending on biofilm thickness, expansion coefficient, media diameter and density. The validity of this expression was tested with the data from this study.

Fluidized Bed Biological Wastewater Treatment: Effects of Scale-Up on System Performance

1990 ◽  
Vol 22 (1-2) ◽  
pp. 419-430 ◽  
Author(s):  
P. M. Sutton ◽  
P. N. Mishra
Keyword(s):  
Fluidized Bed ◽  
Pilot Plant ◽  
Large Scale ◽  
Scale Up ◽  
The United States ◽  
Full Scale ◽  
Fluidized Bed Reactors ◽  
Automotive Manufacturing ◽  
And Performance ◽  
Performance Results

The operation of a number of small and large scale biological fluidized bed pilot plants over the past ten years has resulted in the derivation of process and component information for design of commercial facilities. The General Motors (GM) Corporation represents the single, largest industrial user of the technology in the United States. Ten fluidized bed reactors are located at GM automotive manufacturing facilities. Nine of the reactors are designed to treat wastewaters originating from metalworking operations pretreated for removal of petroleum oils. The other reactor is designed for treatment of sanitary waste-water. In 1984 and 1985, GM completed extensive pilot plant studies and on the basis of the results selected the aerobic fluidized bed (AFB) process configuration for full scale implementation at various plant sites. The fluidized bed reactors located at the sites range in reactor volume from approximately 60 to 730 m3. The pilot plant results which formed the basis for process design of the full scale reactors involved operation of 77 l fluidized bed reactors. Operating information and performance results were derived from evaluation of full scale GM fluidized bed reactors located at the New Departure Hyatt (NDH) plant in Sandusky, Ohio and the Oldsmobile engine plant in Lansing, Michigan. The full scale results were compared to the pilot plant results with the objective of understanding the effects of scale-up on system operation and performance. A comparable level of reactor attached volatile solids (VS) was measured in the pilot and full scale reactors. Biomass net yield coefficients were higher in the full scale reactors, likely due to differences in the composition of the wastewater fed to the full scale versus the pilot scale units. Oxygen utilization coefficients were comparable. The full scale performance results compared favorably with results from the pilot plant studies on the basis of the relationship between effluent quality and reactor solids retention time (SRT).

Modelling of Fluidized Bed Reactors

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Joachim Werther ◽  
Ernst-Ulrich Hartge
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Fluidized Bed ◽  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Scale Up ◽  
Fluidized Bed Reactor ◽  
Fluidized Bed Reactors ◽  
Model Calculations

The fluidized bed reactor has a lot of advantages: excellent gas-solid contacting, no hot spots even with highly exothermal reactions, good gas-to-particle and bed-to-wall heat transfer and the ease of solids handling which is particularly important if the catalyst is quickly ageing. However, the list of disadvantages is as long: broad residence time distribution of the gas due to dispersion and gas-bypass in the form of bubbles, broad residence time distribution of solids due to intense mixing, erosion of bed internals and the attrition of the catalyst particles. A particular disadvantage of the fluidized bed reactor is its difficult scale-up. The historical experience with the FCC process is that in the early 40's of the last century this process was successfully scaled up from a 5 cm dia. pilot-scale unit to a 4.5 m dia. bed in the production unit. On the other hand, around 1950 the scale up of the Fischer-Tropsch synthesis in the fluidized bed failed completely. Modern process design should be able to avoid such disasters by making use of modeling and simulation tools. However, a modeling tool which is really helpful in planning and designing of an industrial fluidized bed reactor has to fulfill a lot of requirements. It should be able to describe the influence of the several changes which are typical for the scale-up process, for example enlargement of bed diameter, bed height and fluidizing velocity, changes of gas distributor design, introduction of in-bed heat exchanger tubes and baffles. In the present work a modelling approach is presented which is able to handle the most important aspects of industrial fluidized bed reactors. A particular focus is to describe the relationship between catalyst attrition, solids recovery in the reactor system and chemical performance of the fluidized bed reactor. The competing influences of attrition of the catalyst particles and efficiency of the solids recovery lead to the establishment of a catalyst particle size distribution (PSD) in the bed inventory which in turn influences via the hydrodynamic characteristics of the fluidized bed the performance of the chemical reactor. The usefulness of this approach is illustrated with model calculations for a fictituous first order reaction where the fluidized bed is equipped with different solids recovery systems including one single stage cyclone, several cyclones in parallel, two- and three-stage cyclone systems, respectively. Model calculations illustrate the significance of a high efficiency of the solids recovery in order to keep the fines in the system which is decisive for a high performance of the reactor. The calculations reveal that it may take months until a quasi steady state of the bed particle size distribution is obtained.

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