TL;DR
Nozzle fouling causes asymmetric spray and downstream product quality deviation. Stop the dryer, remove the nozzle, and clean per the general solvent cleaning procedure.
What you might see
- spray pattern asymmetric or absent
- product buildup visible at nozzle tip
- differential pressure across nozzle rising
- outlet temperature above setpoint despite normal feed rate
Likely causes
Feed liquid solidifying at the nozzle orifice during startup or shutdown transition
Feed liquid concentration above design causing early crystallization at the tip
Nozzle tip wear enlarging the orifice and altering spray angle
Insufficient atomizing air pressure allowing liquid weepage at shutdown
Required tools
- Heat-resistant gloves
- LOTO kit
- Nozzle cleaning solvent (approved for product contact surfaces)
- Soft-bristle cleaning brush
- Nozzle orifice gauge
Safety first
- Spray dryer chambers can reach several hundred degrees C at the inlet. Confirm the chamber is cool before entering or reaching inside.
- Spray-dried pharmaceutical powders can be potent or sensitizing. Wear respiratory PPE when cleaning nozzles or opening the chamber.
- Cleaning solvents used on product contact surfaces must be approved for GMP residue limits.
Procedure
- 1
Stop the feed pump and allow the atomizing air to run for 2 minutes to clear residual liquid from the nozzle.[1]
- 2
Shut down the dryer per the normal shutdown sequence. Lock out and tag out the heater, fan, and feed pump.
- 3
Wait for the chamber wall temperature to fall to a safe handling temperature (below 50 degrees C).
- 4
Remove the nozzle assembly per the general disassembly procedure. Wear heat-resistant gloves.
Warning: Chamber walls and nozzle assembly may be hot. Confirm temperature is safe before reaching inside the chamber. - 5
Soak the nozzle in the approved cleaning solvent. Use a soft brush to remove deposits. Do not use metal tools on the nozzle orifice.[1]
- 6
Inspect the orifice for wear or enlargement using the supplied orifice gauge. Replace the nozzle if the orifice is out of tolerance.
- 7
Reinstall the nozzle, confirm the O-ring or gasket is seated, and check the atomizing air connection before restarting.
Sources
GEA Niro GEA Niro PSD / Mobile Minor Spray Dryer general technical documentation, GEA Niro
GEA Niro PSD / Mobile Minor spray dryer general nozzle maintenance and cleaning procedures (general)
More guides for GEA Niro GEA Niro PSD / Mobile Minor
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A blocked cyclone reduces yield and increases chamber powder accumulation. Stop the dryer, isolate the cyclone, and clear the blockage using a soft tool.
How to fix outlet temperature deviation on a GEA Niro PSD / Mobile Minor spray dryer
Outlet temperature is the primary product quality control parameter in spray drying. Verify sensor calibration, then check feed rate and inlet temperature before adjusting setpoints.
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