Sometimes we may already judge the feasibility of spray drying based on experiences with different products. Nevertheless slightly changed physico-chemical properties may change the final product properties drastically. Therefore we always execute tests within a laboratory scale. Very often the attributes of a dried final product are to be changed expressively. For that, we consider it necessary to execute tests within a semi-technical scale. In this case those nozzles will be applied which will be also used in the later production dryer. By this, the scale up of the spraying will be certainly assured.

2. Technical Data
2.1 Laboratory apparatus LTA, LTC and LTK
Drying: Cocurrent
Operation: open or LTK closed cycle
Evaporation capacity: 1 to 7,5 kg/h Water
Inlet temperature:; 60 to 250 °C
Outlet temperature 50 to 150 °C
Spraying: with 2-fluid-nozzles
Separation:
LTA onepoint outlet at cyclone, twopoint outlet at cyclone and tower
LTC and LTK
onepoint at bagfilter, twopoint at cyclone and bagfilter, threepoint at tower, cyclone and bagfilter
Solvent recovery: LTK condensator
Heating: indirectly electrical
Necessary wet material amount: 0.5 to 2 kg
 

2.2 Technical plant
Drying: cocurrent and semicountercurrent
Operation: open or closed cycle with selfinertization
Evaporation capacity 10 to 100 kg/h Water
Inlet temperature: 80 to 450 °C
Outlet temperature: 50 to 150 °C
Spraying:
onefluidnozzles (pressure nozzles, hollow cone nozzle),
two-fluid-nozzles
multi-fluid-nozzles
Separation: by cyclone and/or bagfilter
Post-cleaning: scrubber with droplet separator
Heating: direct natural gas heating
Necessary quantity of wet product 20 to 50 kg for each parameterset
 

The following process lines are possible

• Feed out of the coarse products at the tower, fine product separation within the cyclone and/or bagfilter, scrubber
• Fine product return towards the spraying area.
• Injection of antiblockingagents (ABM)
• Input of cold air towards the lower part of the tower.
• Cooling of the dried final products by pneumatic transport.
• closed cycle for explosionsprotection against dustexplosion with selfinertization
• Afterdrying in the integrated or external fluidized bed dryer.

There is a pneumatic transport system for the drying of flowable wet product. The product will be transported to the tower-head and distributed with a pneumatic nozzle or simply injected.

By means of positive displacement pumps we can convey low to highly viscose liquids (viscosities up to 20.000 mPasec or centipoise).

The plant is provided with regulators for maintaining the interesting quantities. Hereby the automatic permanent operation can be demonstrated. The measured values will be logged with a PC-based digital control system.

2.3 Nozzle Test Equipment
for one fluid nozzle, two fluid nozzle and multiple channel nozzle

measured Values
liquid pressure
Compressed air throughput
Compressed air pressure
Droplet size with laser difraction

2.4 Analysing possibilities at wet product
temperature
density
content of moisture
particle size distribution with flowable wet products
viscosity
drying properties

2.5 Analysing possibilities at dryed product
bulk density
content of moisture
particle size distribution with laser difraction or sieving
flowability