CENTRIFUGE DECANTER AND HOW IT WORKS

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2 CENTRIFUGE DECANTER AND HOW IT WORKS

3 DECANTER CENTRIFUGE In a decanter there s a continuous mechanical separation of suspended solids from a liquid or liquids You could see a centrifuge decanter like a gravity settling tank, the difference is the centrifugal force : it improves the settling time and efficiency!!

4 Gravity settling tank Sludge Feed Solids discharge Clarified liquid outlet Solids deposit

5 Gravity settling tank equivalent to a Decanter

6 Centrifugal acceleration 2 Ac = rω ω = 2 π n 60 Ac = centrifugal acceleration ω = angular velocity (radians / sec) n = rotation speed (rpm) r = radius

7 G Force G-force is defined as the ratio between the centrifugal acceleration created inside the bowl and the earth gravity acceleration g=9.81 m/s 2 G r 2 g For the CBB decanters: 3000 < G < 5000

8 Equivalent Area (A e ) The settling ability which indicates the decanter settling capacity is calculated as the surface area needed to a settling tank to obtain the same task L Area= 2R L 2R L R A e G Force g R = bowl radius L = distance between feed point and liquid outlet

9 Equivalent Area Sigma factor L 2 ( R b 1 2 R1 ) L 4 g The parameter takes into account that force G varies with the radius R b = bowl internal radius R 1 = liquid outlet radius L = distance between feed point and liquid outlet

10 How the Decanter Works Gearbox Beach (conical) section Scroll clarified liquid pond Scraper Baffle disc Cylindrical section Feed zone Bowl Sludge Feed pipe Solids discharge Solids deposited Liquids discharge

11 Shallow cone bowl Bowl type Steep cone bowl

12 Baffle plate Feed zone Baffle disc Polymer injection Lack of a baffle plate results for a biological sludge results in a sludge that is several percentage points less in dryness. When squeezing the sludge, it will try to take the exit of least resistance, this is the center of the centrifuge where G-forces are the lowest. The baffle plate stops these solids to leave the centrifuge through the liquid discharge, and allow them to be squeezed to the maximum H The baffle also allows positioning the liquid discharge higher than the solids discharge, thus creating a substantially increased dewatering volume

13 Decanter with variable differential speed 8 (hydraulic back drive) LEGEND: BUS DATA 1. Main motor 2. Gearbox 3. Scroll Belt 4. Bowl belts 5. Hydraulic punp 6. Hydraulic motor 7. Heat exchanger 8. Touch screen 9. DPC (Decanter Process Controller)

14 6 Decanter with electric back drive BUS DATA LEGEND: 1. Main motor 2. Gearbox 3. Scroll belt 4. Bowl belt 5. Scroll motor 6. Touch screen 7. DPC (Decanter Process Controller)

15 Differential speed regulation Hydraulic regulation Electric regulation

16 Decanter control and management system Touch screen (Writing) Touch screen (Reading) Decanter DPC

17 Scroll: wear resistent protection solid steel bar welded hard part Tungsten Carbide Open scroll construction made with solid steel bars

18 Vertical removal of the rotating assembly

19 Full geared scraper mechanism to prevent sludge built up in the solids discharge chamber Scraper

20 Construction details Individual inspection covers for the liquids and solids discharge chamber Ceramic discharge bushings Liquid weirs easy to adjust (one plate for 14 positions) Extremely easy to replace Solid and liquids discharge replaceable and in solid stainless steel not just cladded

21 DECANTER REGULATION AND OPTIMIZATION

22 Decanter Adjusting Adjust polymer rate Dirty centrate. Acceptable cake Clean/dirty centrate. Wet cake

23 Performance optimizing n r R Q To optimize the performance set the following parameters: Q= feed rate d = flocculation = viscosity n = RPM n = differential speed (R-r) = Pond depth

24 Adjusting the weir plates Most others

25 Performance optimizing Influence of flocculation, rotational speed and feed rate on separation efficiency Vg 2 d ( ) s l 2 r 18 ω Q

26 Oil reservoir integrated in the leg of the decanter

27 CBB mobile plant LEGEND: 1. Control panel 2. Decanter 3. Sludge conveyor 4. Polymer station 5. Sludge punp 6. Polymer pump