An investigation of the entrance region of a riser fluidized bed.
Item
-
Title
-
An investigation of the entrance region of a riser fluidized bed.
-
Identifier
-
AAI9813982
-
identifier
-
9813982
-
Creator
-
Kostazos, Apostolos E.
-
Contributor
-
Adviser: Herbert Weinsten
-
Date
-
1997
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Engineering, Chemical | Engineering, Mechanical
-
Abstract
-
The performance of a riser fluidized bed reactor is dependent on rapidly mixing jets of reacta nt fluid (gas or volatile liquid) through a flowing gas-catalyst powder mixture. Since riser reactors are typically employed with fast reaction systems, riser length is not long, typically being the 20 to 30 diameters which make up an entrance length. The rapidity of the initial mixing process and the suppression of backmixing are, therefore, critical in maximizing selectivity and yield.;An experimental work was carried out to determine the effect of the nozzle configuration on the mixing of the gas and catalyst powder. For this work the 15.2cm ID City College riser was used, equipped with a new entrance section. This added to the system two more operating conditions, the radial position of the gas injection and the ratio between the primary and secondary or "fluffing" air flowrate. The facility is equipped with the necessary instrumentation for axial and radial pressure difference measurements, radial solid density and solid flux measurements.;The results showed that the radial position of the gas injection plays the dominant role in determining the rapidity of the mixing of gas and catalyst. Gas injection close the riser axis creates a flow with strong radial concentration and velocity gradients which increase the backmixing and reduce the degree of contact between gas and catalyst. On the other hand, gas injection close the riser wall creates a flow with much flatter density and velocity profiles and therefore good gas solid contact and minimization of backmixing which results in higher reactor performance. The database provided with this work can be used as guidance for improved phenomenological design of this kind of reactor and also for the development of a two-dimensional CFD model.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
