This BoHiBar drum filter is operated for steam pressure filtration of an organic acid. The suspension coming from the reactor consists of organic crystals suspended in water and is enriched with salts that are completely dissolved in the filtrate. To produce a clean product the dissolved salts have to be removed by washing of the filter cake.

Former process with a vacuum drum filter:

On a vacuum drum filter of 80 m² with string discharge the formed filter cake was washed and dewatered. The filter cake had a moisture content of 50 wt-% and was thixotropic. The strong thixotropic behaviour required cake discharge by strings and liquefaction to allow feeding to a spin flash drier (low energetic efficiency h = 50%).

New Process Design with BoHiBar Steam Pressure Filtration:

With BoHiBar steam pressure filtration on a BoHiBar Drum filter of 40 m² filter area, a clean filter cake is achieved with a moisture content mc < 26 wt-% so that the product is no more thixotropic and not sticky. This allows thermal drying in a tray drier with a much better energetic efficiency of h = 90% compared to the spin flash drier. This leads to process simplification, reduction of operating cost and improvement of product characteristics.

BoHiBar Drum Filter L40

Units installed



Filter area per unit

[ m² ]


Material of construction



Power of filter drive

[ kW ]


Year of commissioning




Process and Operation Data

Solids throughput

t DS/h ]


Cake moisture

[ wt.-% ]

< 26

Steam per t solids



Operation pressure

[ bar (g) ]



Product Data



Organic acid crystals
(Naphthalene-Sulphonic Acid)

pH value of suspension

[ - ]

1 - 2

Medium particle size

[ µm ]



[°C ]


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