Cleaning in Place of Spray Drying Plants

The nature of dairy and food products means that the possibility for product deposits forming on the surfaces of process equipment is always a threat. This is primarily due to the fat, sugar, and/or protein content of these products, giving hygroscopic and sticky characteristics at the temperature and humidity conditions present during processing. The longer the plant operates, the greater is the chance for deposit formation.

Niro has successfully developed designs of evaporators, dryers, and associated equipment that minimize deposit formation and permit plant operation over longer and longer periods of time. However, there comes a time when the plant has to be shut down for cleaning, and cleaning-in-place has become essential to minimize cleaning time and thereby maintain high plant production availability.

Niro has developed washing systems applicable to cleaning individual equipment items or a complete plant. These systems are based upon Cleaning-in-Place (CIP) nozzles that are built into the plant components together with associated piping, fittings, and instrumentation. The Cleaning-in-Place (CIP) operation is normally computer controlled. A Programmable Logic Controller (PLC) program controls pump and valve functions, and the cleaning sequences are given the optimum timing for efficient cleaning of all parts of the plant. The system is flexible in that different washing programs may be applied.

Operation of a Typical Cleaning-in-Place CIP) System

In the first cycle, water is pumped through a heater to the cleaning turbine and/or to the Cleaning-in-Place (CIP) nozzles placed throughout the system. The first liquid flush is normally sent to drain or to a separate collecting tank. The wash water is filtered and returned to the rinsing tank prior to being reused. The washing procedure is repeated. The Programmable Logic Controller (PLC) controller regulates the length of the washing period.

The next cleaning cycle involves a caustic solution as the washing medium. It is primarily used where harder deposits are expected. To enable repeated use of the caustic, separation of product solids from the liquid may be necessary.

Another washing cycle takes place by switching back to the rinsing water tank.

An acid cleaning cycle circulates acid for final washing and neutralizing the caustic remaining on the surfaces of the equipment. Acid cleaning is always used in the wet processing areas, i.e. the feed system, tanks, homogenizers, and atomizers.

A final clean water washing is the last stage of the cleaning process. In order to dry the system before startup, air heaters and fans force warm air through the plant.

Download the CIP - Cleaning-in-Place of Spray Drying Plants brochure (pdf).