ACHEMA Highlight: Filter innovations for more flexibility of continuous fluid bed and spouted bed equipment

Plate filter design – space saving filters on display at ACHEMA

Fluid bed equipment requires high buildings, which are not always available. Additional space is necessary to service the filter on top of the already tall equipment. Up to 2.5 meters are required above the fluid bed contraption in order to exchange 6 m long filter bags.

Manufacturers have been offering the possibility to place filter elements horizontally into the filter housing for installations, where dismantling of the filter elements to the top is not possible. These filters are serviced from the side, where the clean gas also leaves the unit.

Glatt has now, for the first time integrated such horizontal filters into the fluid bed. The height of the equipment is decreased by putting the clean gas chamber to the side, resulting in no space being required above the fluid bed unit. Doors on the side of the clean gas chamber enable easy access to the filter elements. Exchanging of the filter elements is in actual fact easier from the side compared to the top.

A further advantage is the possibility to design the room at the side of the clean gas chamber as a wash room with a solid floor and tight connection to the fluid bed unit. The dust-loaden filters are handled only within this room, contaminating no other parts of the plant with the filter dust. Having removed the filter plates the complete fluid bed unit can be washed in place. With this design it is very rarely necessary to open the fluid bed unit in the production area.

The plate filter has been tested on a prototype designed GF 20 in our laboratory with the first successful application tests being carried out in March 2008. Our new PROCELL 25 demonstrating the plate filter will be on display at the ACHEMA 2009. This unit will be installed in our new laboratory building and will be available for tests in the fourth quarter of 2009.

WIP bag filter – no dismantling of filter bags during wash cycle

Wash in place – bag filters have also existed for several years. Glatt has frequently used them for the design of continuous fluid beds. Washing nozzles are installed in the clean and raw gas chamber at the top of the filter bags. During the wash cycle they flush the filter bags from the raw gas side and wash down all the dust on the surface.

The quality of the washing process depends on the product. Our experience shows that in many applications the filters are clean for the next product.

In order to improve the efficiency of the WIP step and to adjust the design of the specific granulator needs, we have now developed our own design of spray nozzles and filter bags. The filter has been installed in a GFG 250 and will soon be tested in full scale. Tests on our pilot unit were successful in 2008.

After washing and rinsing the filter bags are dried in the fluid or spouted bed unit, and the next production campaign can start. This filter has a walk-in clean gas chamber for servicing the filter bags and the pulse back system and is also washed in place. Entering the clean gas chamber is only necessary during maintenance. Hence nobody needs to enter the processing equipment during normal production and cleaning cycles.

A new pilot unit for the production of granules and pellets made from solid and/or liquid raw materials by fluid bed and spouted bed processes will be installed in the laboratory extension at Glatt in Weimar in 2009. All commonly used filter types can be tested with this unit:

• pleated cartridges,
• filter bags,
• metal filter cartridges,
• filter plates.

The GF/ProCell 25 is not only flexible with regards to the filter system, but also a flexible spraying system and the possible change of the inlet air chamber to switch between ProCell and Glatt fluid bed (GF) demonstrates the state of the art design of the pilot unit.