BUCHI Inert Loop B-295 - Manual (Page 22)

4 Description of function
22 B-290 Operation Manual, Version I
4 Description of function
This chapter explains the basic working principle of the Mini Spray Dryer B-290 Basic (open mode
only) and the Mini Spray Dryer B-290 Advanced (for closed mode operation). It also shows how the
instruments are structured and provides a general functional description of the assemblies.
4 .1 Functional principle of the drying gas
The Mini Spray Dryer B-290 operates according to a co-current drying gas (e.g. air in open mode)
and product stream. This means that sprayed product and hot gas have the same flow direction from
downward.
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7
1
3
4
8
2
6
a Gas inlet (optional with attached inlet filter)
b Electric heater
c Concentric inlet of the hot gas around the
spray nozzle
d Spray cylinder
e Cyclone to separate particles from gas
stream
f Product collection vessel
g Outlet filter
h Aspirator to pump gas through system
Fig. 4.1: Functional principle of the drying air
4 .2 Functional principle of the sample feed and dispersion
The Mini Spray Dryer has a integrated two-fluid nozzle: Compressed gas (normally air or N
2
) is used to
disperse the liquid body into fine droplets which are subsequently dried in the cylinder.
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2
3
5
4
6
a Feed solution
b Peristaltic pump
c Two fluid nozzle
d Connection for cooling water
e Connection for compressed spray gas
f Automatic nozzle cleaning system
Fig. 4.2: Functional principle of the sample feed and dispersion
Spraying nozzle
The nozzle consists of the nozzle tip with a 0.7 mm dia meter hole and the nozzle cap
(1.4 or 1.5 mm in diameter). This geometry results in a mixing of fluid body and gas.