GEA redesigns SANICIP bag filter for spray dryers

To-scale image of the SANICIP II. Image courtesy of GEA

GEA has made a series of important changes to its SANICIP bag filtration system for food and dairy spray dryers in a long-term development project that will reportedly provide valuable operational benefits to users of the new equipment. The new SANICIP II (patent pending) maintains and controls the pressure drop through the filtration bags more effectively by promoting longer production times and reducing CIP intervals. Combined with other advances, such as easier maintenance and better space utilisation than its predecessor, bag life is now up to 50% longer.

Following extensive studies with customers, GEA identified key areas where design modifications could be made in this new generation of SANICIP technology. Using the latest computational fluid dynamics (CFD) techniques to optimise airflow within the filter, GEA was able to reduce the length of the filter bags from up to 7 meters to just 4.5 meters and, by reducing the diameter, and increasing the number of bags within the filter chamber, retained the total filtration surface area of the system.

This fundamental change results in increased practicality and efficiency while contributing several additional benefits, according to GEA:

Shorter filtration bags and cages

Each filtration bag is supported by an internal cage structure. The 4.5-meter cages are much lighter in weight than their longer predecessors making maintenance easier. Likewise, the shorter cages can be fabricated as a single piece, rather than joining two structures, allowing the cage to come more easily and more quickly into position. And its rigidity makes it more structurally sound. GEA has also made the fixing system for each cage obsolete, thereby eliminating the need for loose bolts, nuts and brackets which were difficult and time consuming for engineers to handle during routine maintenance. The shorter filtration bags are exposed to less turbulence making them less prone to mechanical wear and thereby extending their operational life by up to 50%.

More resilient dedusting system to better maintain pressure loss

GEA has also looked closely at the design of its dedusting system, essentially comprising super-sonic nozzles and rapid diaphragm valves. The system ensures the powder that builds up on the bags is pulsed down into the bottom of the filter. Using CFD techniques combined with full-scale testing has allowed GEA to make precise adjustments to the profile of the super-sonic nozzles and their position, and to the design of the diaphragm valve. This, combined with the shorter bags and the novel inlet system (see below), ensures that the powder on the bags is carefully controlled and never exceeds the desired level. As a result, the need for frequent cleaning, which would otherwise seriously affect production schedules, is drastically reduced and the pressure loss through the bags can be maintained indefinitely. Improved dedusting capability was already made available in more recent SANICIP models and with these additional updates, is now fitted as standard on the SANICIP II.

Adaptive layout featuring novel inlet solution

GEA made another important change by redesigning the inlet from the spray dryer, which is now vertical instead of horizontal. This facilitates a much more even distribution of air within the filter, reduces the footprint required and allows for a more adaptive plant layout. This adaptive layout may in some instances allow for lower building heights, thereby lowering capital investment, which can be substantial, particularly in areas with high regulatory cost and requirements, such as in earthquake-prone zones.

Operational benefits

Stig Møller Andersen, product manager for GEA in Copenhagen, stated: “We listened carefully to our customers’ concerns and systematically addressed them in the new SANICIP II. The result is a bag filtration system that effectively supports the spray dryer while providing a wide range of operational benefits for the user.”

Taken together, the optimisation of the SANICIP II, compared with previous models, delivers a range of benefits for food and dairy powder processors, according to GEA. The most significant is the ability to control pressure loss across the filter bags thereby extending production times and reducing the need for CIP cycles. The inlet ductwork is simple and compact allowing the filter to be placed closer to the dryer, and the shorter filtration bags experience less turbulence so are less prone to mechanical wear. These modifications extend the operational life of the bag from 12 to 18 months or 12 CIP cycles – whichever comes first – providing substantial savings on maintenance costs and improved uptime. The reduced number of CIP cycles, and lower costs for spare parts leads to an optimised total cost of ownership (TCO).

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