CIP cleaning time is defined as: Product off → Product on. This means that preparation time of the plant for wet-cleaning is included.
A full CIP of an evaporator is done within 2-3 hours. This is possible because the CIP cleaning is done while the evaporator is still under vacuum - however, the vacuum is adjusted so that the correct temperature of the cleaning liquid is obtained also in the last effect.
Depending on product and product quality there will be more or less deposits from the pasteurization section. These deposits appear as jelly lumps due to interaction with the NaOH and are removed in a hydro cyclone so that they will not block the small holes in the distribution plate. Therefore, it is not necessary to open the evaporator (break the vacuum) for inspection or manual cleaning. The evaporator is ready for a quick start-up and valuable production time is not lost.
CIP cleaning of the spray dryer is divided into two sections for the running time: the wet part which is the feed and atomization system and the dry part which is the rest.
For milk powder, the wet part is cleaned every 20 hours. For other food products such as coffee, baby food, and coffee whitener it is possible to produce for a longer time. GEA Niro has designed a CIP stand for the atomization unit that fits both a rotary atomizer and high-pressure nozzles. The rotary atomizer or nozzle lances are connected to the CIP circulation system which consists of a small closed container where the rotary atomizer wheel or nozzle orifices are placed. With this system little manpower is needed and the CIP time is reduced to a minimum. Typically, the evaporator and dryer liquid system are cleaned simultaneously.
Wet cleaning of the dry part of the spray dryer is quite another matter: much more difficult and time consuming. GEA Niro has designed a retractable CIP nozzle for ducts, cyclones, and the VIBRO-FLUIDIZER™ as well as other components that cannot be cleaned by a simple flushing of the CIP liquid. Thus, it is not necessary to spend time/manpower to install the CIP nozzles as they are permanently welded on the component to be cleaned. The CIP nozzles can be delivered either as hydraulically activated or activated by compressed air. To monitor their position, they can be equipped with limit switches.
CIP drain funnels can be supplied so that only part of the plant is cleaned – e.g. the drying chamber.
If the plant is equipped with a CIP-able bag filter SANICIP™ as designed by GEA Niro, it will be delivered with specially designed nozzles with a dual purpose. During CIP, clean water is sprayed into the bags so that they are cleaned from the inside out. This patented feature secures a reduction of the total CIP time and also reduces the total amount of CIP liquid to the sewage system.
A full CIP turn-around time depends on many things, the most important being:
- the amount of deposits in the plant
- the manpower available to make the plant ready for the actual wet-cleaning
- the number of CIP tanks
- the number of CIP circuits
Ad 1: The amount of deposits depends on product composition, production parameters and control of air flow into the drying chamber. GEA Niro has developed a new air disperser that in many cases can improve the air flow and distribution into the drying chamber, whereby deposits can be reduced.
Ad 2: Obviously the number of people available to change the dryer into a “CIP mode” and back again reduces the total CIP time.
Ad 3 and 4: The more CIP tanks and circuits, valves and pumps, i.e. investment, the shorter CIP time. This means that “down time” can be converted to production time. A CIP time – from product off to product on – of approx. 14 hours is realistic, if all the above is taken into account. For the Integrated Filter Dryer IFD™ a turn-around time of less than 10 hours has been reported.