Introduction
Chapter 1 (continued)
Special Notes on the Accessories
Only the 5 litre glass tub assemblies, both those using filter bags and the sealed
variety, can have an inlet for the outlet humidity and temperature probe. Only
these tubs can fully utilise all the features on the Fluid Bed Dryer.
The glass tubs have an advantage in the operator being able to see the sample as
it dries. The optimum flow rate is easy to select judging by the appearance of the
fluidised sample. The operator is often able to estimate the state of dryness and
guess the shape and size distribution of the particles simply by the appearance of
the sample flowing in the tub. The main advantage of the stainless steel tubs is
durability. High-grade stainless steel is used since the process requirements
usually call for high product purity and good chemical and corrosion resistance at
high temperature. Other specialised tub assemblies which can be used on the FBD
include a Particle Classifier and a Sieve Dryer.
The mini tubs are 250ml in capacity and can be used effectively on samples
weighing from 5 to 50 grams per tub. Four tubs can be dried simultaneously.
The decision to go to sealed tubs is based simply on particle size. Below 45
microns, we suggest you go to a sealed tub.
The 3 micron polyester filters can be used for the mini tubs as well as the 2 and 5
litre tubs. These filters are effective for 5 to 25 micron particles. Please note that
these filters greatly reduce the flow rate of air through the sample. Drying times
normally occurring between 10 to 30 minutes can take up to several hours using
these small pore size filters. Furthermore, the use of these filters may even hinder
the mixing of sample particles during drying. Many of the main advantages of fluid
bed drying may be lost. If in doubt, Endecotts offer to do an initial study on your
sample which will ensure proper accessories are chosen for the application.
A wet sample should occupy about 1/3 of the tub assembly volume. As it dries
and the density drops, the apparent volume will increase to about ½ the volume.
Tubs should be purchased that are 3 x the volume of the sample size.
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Summary of Contents for Fluid Bed Dryer
Page 1: ...USER GUIDE FLUID BED DRYER...