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Vertical grit dosing screw with tank and integrated drum filter screen RoSF 8VT |
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Underground / above-ground storage tank
Inclined screw conveyor
Coarse material separator
Dewatering unit |
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1 Acceptance station
1.1 Acceptance
Depending on how the stainless steel storage tank is installed, the raw material is fed underground or above ground. In case of underground installation, the storage tank is embedded in the customer's concrete basin. The pre-dewatered material is fed into the stainless steel tank with grit removal screw by a tanker vehicle or wheel loader. The water introduced with the material and tanker cleaning water run off slowly through the drain holes in the tank front side. An optional screen accelerates and facilitates water-runoff from the tank. The separated water is flows via a hose line into a pump sump where an optional subermersible pump can be installed to deliver the water into the STP inlet. A massive bar grate is mounted over the tank for retention of bigger particles. The grate can optionally be designed as a vibrating grate.
1.2 Drum Separator
The screw in the tank conveys and doses the material into the annexed drum separator where wash water is added to wash and separate coarse material. The separated coarse material (separation size 10-35 mm) is discharged into a container. The grit/organics/water mixture flows by gravity into the Grit Washing Plant or a grit trap. The drum separator's wash water demand is approx. 15 20 m³ per operating hour.
2. Coanda Grit Washing Plant
The grit/organics/water mixture effluent from the drum separator flows directly into the trough of the Grit Washing Plant. The pressure or gravity line from the grit trap is directly connected to the vortex chamber of the Grit Washing Plant.
The rotary flow from the vortex chamber is redirected from the vertical to horizontal using the Coanda effect, which results in a defined flow pattern in the tank. As sedimentation depends on both the particle size and density, not only the mineral components will settle but also organics.
Actual grit washing, i.e. separation of organics from mineral components, takes place in the lower part of the grit washing plant where the turbulence is reduced. A defined amount of upflow water is introduced into the plant to create a grit fluidised bed which allows separation of the organics independent of the particle size. A rabbling device operated at low speed supports the grit/organics separation. The clean grit is automatically but discontinuously transported by a screw conveyor, depending on the amount of grit which is measured by means of a hydrostatic pressure meter. Whilst being transported, the grit is dewatered prior to being discharged into a skip. Grit is discharged as long as the grit level probe is responding. Also the remaining organic material is automatically but discontinuously discharged from the plant via an automatic valve, depending on the complete process. This process is PLC controlled. The effluent from the Coanda Grit Washing Plant (wash water, organics, etc.) is returned into the wastewater treatment plant. The wash water demand of the Grit Washing Plant is typically 5 m³ per operating hour.
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HUBER - WHERE QUALITY AND SERVICE SPRING TO MIND
Huber Technology UK, Units C and D Brunel Park
Bumpers Farm, Chippenham Wiltshire SN14 6NQ
Phone +44 1249 765000, Fax +44 1249 449076, E-mail: rotamat@huber.co.uk |
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