24/7 optimized drying process
Standard milk powder plants normally run 20 hours before parts of the plant needs to be CIP’ed for controlling bacteria growth as well as fouling of the heating equipment. A CIP cycle of feed system from feed stop to feed run can
take up to 4 hours, meaning more than 16% downtime on expensive production equipment. Further, the shutdown of dryer to water can give irregularities in the powder specifications and thereby an uneven powder quality compared to a continuous powder production with a high degree of powder stability. Additional the energy loss of running the spray dryer on water without getting any powder is also considerably high.
Based on above, rebuilding of the production facilities to make the spray dryer run 24/7 has lots of advantages and the investment is quite often paid back within a very short time. Each case must be thoroughly investigated with the existing plant equipment evaluated and
analyzed to understand the implications and necessary equipment/upgrade to be installed.
Five process areas must be assessed before a 24/7 upgrade, as described below:
The evaporation capacity of the existing process will often not have sufficient capacity to increase the production with 16% as well as it will not be able to feed the dryer inline due to CIP requirements.
There are different solutions to increase evaporation capacity:
Install an additional evaporator to switch between two evaporators to avoid any bacterial growth.
Install an evaporator – a so-called “finisher”, which can concentrate the product from 36 to end concentration.
RO plant to concentrate the incoming product before evaporation.
Buffer system for feed to dryer.
Feed line system:
The feed line system must be a double system where the feedline up to the atomizer is CIP’ed every 10 to 12 hours, often in connection with the finisher. If the existing atomizer is a centrifugal one, then there is a possibility to switch from one system to the other with a very short run on water (less than ½ hour). If the dryer already has a nozzle atomizer system, it will most often be possible to add duplex set of nozzles to the system. The air distribution system also needs to be assessed in terms of the additional nozzles, which might affect the airflow.
Existing production area is normally used down to every square meter, and it can, therefore, be a challenge to re-build and add additional equipment to the facility. However, smart solutions are possible in terms of elevation and platforms for new equipment. Every site needs careful examination to find the most optimal solution.
The existing CIP system needs to be able to CIP the new lines and have surplus capacity in case of new evaporators to be installed.
An update of the existing automation system is required to control the switchovers as automatic as possible to save time and man-hours.
Based on above-mentioned assessments, required capital investment for optimizing the production can be made and thereby the overall business case and the return of investment time is visible. In many cases, making a rebuild can be a fast and lower capital cost alternative to a completely new plant investment, however, each case must be investigated individually.