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EVAPORATIVE COOLING PACKING

Numberless structured packing variants have been used since the inception of tower-like, evaporative cooling constructs.  Early arrangements included planks, boards, and bricks.  At the risk of historical inaccuracy perhaps one can point to the 1936 ACB construct, basically assemblies of side-by-side, corrugated asbestos cement board (thus the name) plates, as breaking grounds as regards performance and somehow anticipating later field developments.

The '50s' and the '60s saw probably the greater strides  namely Carl Munters 1957 patent combining corrugated and flat plates, Kohl and Fuller's 1963 vertically corrugated pack patent and ultimately Bredberg's 1966 cross-fluted design.patent which brought [successful] closure as it were to low-profile, highly efficient packing endeavors.

Cross-flute packing, noted for high efficiency and moderate pressure loss, has been used extensively.  Illustrative media include Munters' CF-12060 and CF-19060, Brentwood's CF-1200 and CF-1900, and Marley's MC-67

Offset-flute packing, developed much later splits and reunites gas and liquid streams along the vertical fill section profile.  Typical media include Hamon's ANCS and Balcke-Durrs' FB-20.

Vertical-flute packing, also referred at times as vertical flow packing and a far more recent design, proffers the largest flute openings available for structured packing today.  By permitting higher liquid trickle down rates vertical flute packing helps maintain the packing walls and paths cleaner of foreign, undesirable material such as biofilms or debris. .     

The beauty of cross-flute structured packing is its ability to inherently achieve, impart or impose a high degree of auto or self- liquid phase distribution even though the latter  role is frequently played by/assigned to specialty trays, pressurized nozzles or open, gravity flow distributor channels or basins.  

BIOLOGICAL TREATMENT PACKING

Structured packing as currently utilized for either aerobic or anaerobic treatment can be similarly categorized.

Cross-flute or crossflow packing, proffering 31 sq.ft. per cu.ft surface area, is typically employed for trickling filters, including nitrification.

Vertical-flute or vertical flow packing, proffering 31 or 40 sq.ft. per cu.ft surface area, is typically employed for applications where media plugging can be a concern.  However, vertical-flute media is not able to redistribute wastewater within each pack and only neglibly from layer to layer.

It is possible to combine both packing types in order to try get the best of each world, a concept and actual arrangement referred to as mixed media.  One could/can aim at stacking the two upper filter media layers with higher reaction rate/higher performance cross-flute packing and utilize less fouling prone, vertical flute packing for all the other layers.  The two upper layers would experiment the higher flushing rates which would tend to keep them clean.  At the same time, the upper cross-flute packs will aid in uniformingly spreading or feeding  incoming wastewater to the vertical-flute packs below.

Cross-flute structured packing  media has been successfully employed in full-scale anaerobic treatment systems.  In particular, Patrick et al document an anaerobic  installation achieving COD removals ranging from 70 to 90% based upon loadings between 2 to 4 kgCOD/day per m3 and typical BOD removals in excess of 90%.  Cross-flute media with a surface area of 30 sq.ft./cu.ft. provided a service life of nearly 20 years.

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www.AerationFundamentals.com - www.ExtendedAeration.com - www.OxidationDitches.com - www.TricklingFilters.com

www.Biotowers.com - www.MembraneBioreactors.com - www.AnaerobicReactors.com - www.AnaerobicFilters.com 

www.UASBs.com - www.EGSBs.com - www.CoolingTowerFundamentals.com - www.EvaporativeCondensers.com

www.DewateringFundamentals.com - www.BioremediationFundamentals.com - www.IncinerationFundamentals.com