Multistage Fluidized Research Articles

Demonstration of the Novel Swing Adsorption Reactor Cluster Concept in a Multistage Fluidized Bed with Heat-Transfer Surfaces for Postcombustion CO2 Capture

This paper reports the experimental demonstration of the novel swing adsorption reactor cluster (SARC) concept in a multistage fluidized bed reactor with inbuilt heat-transfer surfaces for postcomb...

Linear Identification and Design of Optimal Controller for Multistage Fluidized Bed Dryer

In many particulate industries, one of the major unit operations used is fluidized bed drying process. In industries, which process large amount of solids, continuous dryers play significant role. The multistage fluidized bed dryer is adapted in research to improve the drying efficiency of final product. The moisture content is an important controlled variable in any drying process. In the present study, identification of three stage fluidized bed dryer by linear time-series models from experimental data has been done. The transfer functions and step response of three stages were identified. Based on state space model, linear quadratic controller was implemented for the identified model of multistage fluidized bed dryer in simulations. The controller was not implemented on the experimental setup.

A Multistage Fluidized Bed for the Deep Removal of Sour Gases: Proof of Concept and Tray Efficiencies.

Currently there are significant amounts of natural gas that cannot be produced and treated to meet pipeline specifications, because that would not be economically viable. This work investigates a bench scale multistage fluidized bed (MSFB) with shallow beds for sour gas removal from natural gas using a commercially available supported amine sorbent. A MSFB is regarded as a promising adsorber type for deep sour gas removal to parts per million concentrations. A series of experiments was conducted using carbon dioxide as sour gas and nitrogen to mimic natural gas. Removal below 3 mol ppm was successfully demonstrated. This indicates that gas bypassing is minor (that is, good gas–solid contacting) and that apparent adsorption kinetics are fast for the amine sorbent applied. Tray efficiencies for a chemisorption/adsorption system were reported for one of the first times. Current experiments performed at atmospheric pressure strongly indicate that deep removal is possible at higher pressures in a multistage fluidized bed.

Optimization of Stage Numbers in a Multistage Fluidized Bed Temperature Swing Adsorption System for CO2 Capture

A dual loop multi stage fluidized bed process for continuous temperature swing adsorption (TSA) of CO2 is investigated using a thermodynamic process model. The operating case is chosen in accordance with a typical post-combustion CO2 capture process, i.e. 90% CO2 capture rate from a gas stream with 10 vol% CO2 content. Steam is used as the stripping agent on the desorber side. Adsorption thermodynamic data for an amine functionalized sorbent material are employed based on adsorption isotherm data from the literature using the Langmuir model. The optimum stage number on both adsorber and desorber side are investigated with respect to achieve high energy efficiency of the separation process. This means that a low stripping steam demand and a low solids circulation rate are desired. The results show that both solids circulation rate and stripping steam demand are low for configurations with multiple stages for both the adsorber and the desorber. The effect of additional stages is high at the beginning (especially up to three stages) and fades with the number of stages. It can be concluded for the chosen separation task and sorbent that a system with five stages on each side could represent a good compromise between effort and efficiency. Further work will focus on more detailed modeling and on experimental evaluation of the discussed process.

Multistage Fluidized Bed Reactor Performance Characterization for Adsorption of Carbon Dioxide

Carbon dioxide and its different compounds are generated as primary greenhouse gases from the flue gases of coal-fired thermal power plants, boilers, and other stationary combustion processes. This greenhouse gas causes global warming after being emitted to the environment. To deal with this problem, a new dry scrubbing process was tested in this study. A three-stage countercurrent fluidized bed adsorber was developed, designed, and fabricated. It was used as a removal apparatus and operated in a continuous regime for the two-phase system. The height of each stage was 0.30 m, and the inner diameter was 0.10 m. The paper presents the removal of CO2 from gas mixtures by chemical sorption on porous granular calcium oxide particles in the reactor at ambient temperature. The advantages of a multistage fluidized bed reactor for high mass transfer and high gas−solid contact can enhance the removal of the gas when using a dry method. The effects of the operating parameters such as sorbent, superficial gas velocity, and the Weir height on CO2 removal efficiency in the multistage fluidized bed were investigated. The results indicate that the removal efficiency of the carbon dioxide was around 71% at a high solid flow rate corresponding to lower gas velocity at room temperature. In comparison with wet scrubbers, this dry process appears to have lower cost, less complicated configuration, and simpler disposal of used sorbent. The results in this study assume importance from the perspective of use of a multistage fluidized bed adsorber for control of gaseous pollutants at high temperature.

Hold-up characteristics of a novel gas–solid multistage fluidized bed reactor for control of hazardous gaseous effluents

Abstract This paper illustrates the mechanism of gas–solid contacting in a multistage counter-current fluidized bed reactor attached with downcomers. Experimental hold-up study has been carried out extensively using the air and lime particles as gas and solid phases, respectively. The reactor was operated in continuous regime for two-phase system over a wide range of operating conditions including height of the downcomer to determine the solids hold-up at each stage of the reactor. The data was generated under steady and stable operation of the column. Based on the experimental data, empirical correlation is proposed for predicting the solids hold-up in the multistage fluidization. The results in this study assume importance from the standpoint of design and steady operation of multistage fluidized bed reactor with downcomer as an air pollution control system for control of gaseous emissions in the industries.

Role of Pressure Drop in the Counter-current Multistage Fluidized Bed of the Solid-Liquid System. Effect of Non-uniform Liquid Flow.

An experimental study on the pressure drop has been carried out for a counter-current multistage fluidized bed having a downspout as well as on the particle holdup relating to a pressure drop. Three kinds of fluidized beds were used; a 3-stage column with 48.6 mm i.d., a 2-stage column with 99.6 mm i.d. and a batch-wise single stage column without downspout. The holdups for three kinds of ion exchange resins in the multistage fluidized bed are expressed by the correlation obtained for a batch-wise single stage fluidized bed. The pressure drop of the 48.6 mm column, however, varied little with the superficial liquid velocity, while that of the single stage column with the same diameter decreased with an increase in liquid velocity as expected from the theoretical consideration. A 99.6-mm column, where diameter of the downspout is small in comparison with the column diameter, shows that the pressure drop in the multistage column was the same as in the single stage column. By covering a part of stage-partitioning screen of the 99.6-mm column with a plate producing a non-uniform liquid flow, the pressure drop behavior approached the one that is observed for a 48.6-mm column. Discrepancy of the observed and the estimated pressure drops for the multistage fluidized bed is ascribed to the non-uniform flow generated by the downspout which is indispensable to the multistage operation.

Adsorption in Multistage Fluidized Bed Column

Adsorption in Multistage Fluidized Bed Column

Adsorption in Multistage Fluidized Bed Column

The objective of this paper is parameter studies on the adsorption process in multistage fluidized bed column with sieve plates. Based on experimental studies on the fluid-dynamic behaviour, simulation runs are used to evaluate the potential using multistage fluidized bed systems as adsorption units.

Some Drying Aspects of Multistage Fluidized Beds

Multistage fluidized beds with and without downcomers to the horizontal perforated plates are used to dry food materials under different experimental conditions. The influence of various operating parameters such as inlet temperature of the heating medium, flow rate of the heating medium, material flow rate, and number of stages have been investigated. The performance of multistage fluidized beds with and without downcomers is compared and the difference in performance is explained based on stagnancy and short-circuiting of materials in each stage.

Steam Activation of a Bituminous Coal in a Multistage Fluidized Bed Pilot Plant: Operation and Simulation Model

A hydrodynamic and kinetic model was developed and applied to simulate the experimental data from a three-stage fluidized bed pilot plant with downcomers. This was used to study the activated carbon production from a Spanish bituminous coal by steam gasification. The steam gasification kinetics, considering the influence of inhibitors, were also determined in a thermobalance. With the kinetic equation and the experimental solids residence time distribution of the pilot plant, the model simulates the overall process that takes place in the reactor. The proposed model is able to reproduce the experimental results satisfactorily.

A study of stable range of operation in multistage fluidised beds

The range of stable operation in gas-solid multistage fluidised beds (a) with no downcomers, and (b) with downcomers to the horizontal perforated plates has been studied at different experimental conditions. Equations to predict the stable range of operations are proposed based on the experimental data. Solids pressure drop in the two modes of multistage fluidisation was measured and correlations for its prediction have been proposed.

Pressure drop and solids holding time in multistage fluidisation

The study presents an experimental investigation into multistage fluidisation wherein the fluidisation column is sectioned using horizontal perforated plates. The variation in the pressure drop and the solids holding time is investigated in respect of the size, shape and density of the particles, the perforation diameter and the free area of the horizontal plate and the flow rates of the phases. The data are satisfactorily correlated in terms of the relative velocities of the phases, the Froude number, the ratio of particle to perforation diameter and particle to fluid density. The performance of the multistage fluidised bed with and without downcomers to the horizontal perforated plates is critically discussed.

Pressure drop, solids concentration and mean holding time in multistage fluidisation

AbstractCorrelations for the pressure drop, solids concentration and mean holding time of the solids in multistage fluidisation have been presented based on the experimental data of the present study and that available in literature covering a wide range in process variables.

Residence time distribution of solids in multistage fluidisation

The residence time distribution of the solids in multistage fluidisation, wherein downcomers for transferring the solids from stage to stage are provided to the horizontal perforated plates, is experimentally investigated covering a wide range in process variables using flat, baffle and spiral plates developed in the study. The RTD data is modelled using (i) the multiple parameter model, (ii) the diffusional mixing model and (iii) the fractional tank extension model when it is noted that over certain conditions of operation both spiral and baffle plates indicate near piston-flow for the solids without hampering the fluidisation characteristics.

The Flow Pattern of Solid Particles in a Downcomer with an Orifice for Multi-Stage Fluidized Beds

The Flow Pattern of Solid Particles in a Downcomer with an Orifice for Multi-Stage Fluidized Beds

Production of Active Carbon from Coal Char in Cocurrent Multistage Fluidized Beds

Production of Active Carbon from Coal Char in Cocurrent Multistage Fluidized Beds

Production of Active Carbon in Cocurrent Multistage Fluidized Beds

Production of Active Carbon in Cocurrent Multistage Fluidized Beds

Pressure drop of the fluid and the flow patterns of the phases in multistage fluidisation

Staging of a fluidisation column with horizontal screens reduces the axial mixing of the phases and limits the formation and growth of the bubbles. The pressure drop of the fluid and the flow patterns of the phases differ markedly with the mode of operation of the multistage fluidised bed. These aspects with respect to the theoretical models, the experimental data and the range of applicability are discussed along with the correlations to predict the characteristics of the bed.

An experimental investigation of the residence time distribution of solids in multistage fluidisation

The cross-flow model ( Chem. Engng Sci. 1973 28 585), proposed by the authors for multistage systems, is matched with the experimental data taken subsequently on the residence time distribution of solids in a multistage fluidised bed. The model parameters are related to the plate geometry and the flow rates of the phases. The model is found to agree with the experimental data of the earlier investigators on single and multistage fluidised beds with a maximum root mean square deviation of 0·05. Based on the data, conditions for smooth fluidisation are suggested.