BUCHI Nano Spray Dryer B-90 User Manual
Page 26
4 Description of function
26
B-90 Operation Manual, Version B
Optional drying gas recycling in ‘closed loop’ mode:
In ‘closed loop’ mode of the Nano Spray Dryer B-90 Advanced the “Drying gas outlet” i is connected
via the Inert Loop B-295 or Dehumidifier B-296 and Aspirator to the “Drying gas inlet” a.
4.1.2
Spray drying process overview
The drying process takes place inside the drying cylinder. A drying gas flow is established and tiny
droplets of sample material are injected by the spray head. The sample material is dried by the hot
gas. Because of the tiny particle size, an electrical field of sufficient power is needed to retrieve
the particulate material from the drying gas flow. The following scheme informs about the different
processing stages in general.
Drying gas inlet
Flow meter
Electrical heater
Inlet temp. sensor
c
Drying cylinder
d
Electrical particle
collector
Rel. pressure sensor
Outlet temp. sensor
e
Outlet filter
Drying gas outlet
Oxygen sensor
Gas regulator
a
Feed pump
b
Spray head
safety loop
a The “Feed pump” constantly feeds the “Spray head”
with liquid sample material.
b The “Spray head” produces finest droplets and in-
jects them into the “Drying cylinder”.
c The heated drying gas enters laminar from the top
into the “Drying cylinder”. Consequently, the injected
drops of sample material are gently dried to solid
particles.
d The “Electrical particle collector” retrieves the dried
solid particles by an electrostatic field.
e The exhaust gas leaves the spray dryer via the “Out-
let filter” which retains free particles from the gas.