Method for cleaning a nozzle arrangement in a spray drying apparatus, and spray drying apparatus for carrying out the method

A method for cleaning a nozzle arrangement of a spray drying apparatus during operation, the method comprising:

• providing a spray drying apparatus with a drying chamber;
• providing at least one pressure nozzle arrangement inserted into the drying chamber and having a feed inlet and a feed outlet;
• providing a feed conduit for supplying liquid feed to the feed inlet of each nozzle arrangement at a predefined pressure for atomization of the liquid feed;
• providing a cleaning system configured to clean the at least one nozzle arrangement;
• halting the feed supply for the at least one nozzle arrangement to be cleaned during operation;
• removing the at least one nozzle arrangement from the drying chamber;
• and
• cleaning the at least one nozzle arrangement in the cleaning system, wherein after the feed supply is halted and before the at least one nozzle arrangement is removed from the drying chamber, the at least one nozzle arrangement is emptied for feed via one or more of:
• supplying a liquid at substantially the same pressure as the predefined pressure of the feed supply to the feed inlet of the at least one nozzle arrangement,
• supplying pressurized air or gas at a pressure of at least 16 bar to the feed inlet of the at least one nozzle arrangement,
• applying suction from the feed inlet of the at least one nozzle arrangement, or
• applying an additional stream of pressurized air or gas concentrically of the feed outlet of the at least one nozzle arrangement.

A spray drying apparatus comprising:

• a drying chamber;
• an air disperser;
• at least one pressure nozzle arrangement;
• a feed system;
• a feed emptying system, wherein the feed emptying system is configured to empty the feed while maintaining atomization in the at least one nozzle arrangement;
• and
• a cleaning system.