Sizing Decanters

1 of 2 Source: Coulson and Richardson's Chemical Engineering Volume 6 - Chemical Engineering Design (4th Edition) By: Sinnott, R.K. © 2005 Elsevier Inputs Heavy Liquid flow rate Heavy Liquid density Heavy Liquid Viscosity Light Liquid flow rate Light Liquid density Light Liquid viscosity Droplets diameter Holdup time Height to diameter ratio The inlet velocity for decanter

2444 940 3 13346 1000 1 20 10 2 1

kg/hr kg/m3 mNs/m2 kg/hr kg/m3 mNs/m2 µm min m/sec

5388 58.7 3 29416 62.4 0.5 150 10 2 3.28

lb/hr lb/ft3 Cp lb/hr lb/ft3 Cp µm min ft/sec (recommended value)

Calculations Settling velocity of the dispersed phase droplets -0.000655977 m/s -0.655977445 mm/s Continuous phase volumetric flow rate 13 m3/hr 0.00371 m3/sec Area of the interface 5.6517 m2 radius of the cylinder 1.3413 m Diameter of the cylinder 2.6825 m Height of the cylinder 5.365 m Dispersed band height 0.537 m 817.87 sec Residence time of the droplets in the dispersion band 13.63 min Velocity of Oil phase 0.000127819 m/sec Checking droplets diameter Droplets diameter 0.00010827 m 108.2700149 µm Check Adjust droplets diameter

8.80 ft 17.60 ft

Piping Arrangment Feed flow rate Cross Area of Pipe Pipe diameter

0.004429795 m3/sec 0.004429795 m2 0.075101199 m 75.10119905 mm 2.96 inches Take the position of the interface as half-way up the Vessel and the light liquid off take as at 90% of the vessel height 90% Height from datum to light liquid overflow 4.83 m 15.84 ft Height from datum to heavy liquid overflow 2.68 m 8.80 ft Height from datum to the interface,m 4.70 m 15.42 ft Proposed design 8.80

15.838

Light Liquid Take-off

15.415

8.799

Heavy Liquid Take-off

2 of 2 User's input Handbook of Chemical Engineering Calculations, Fourth Edition by: Tyler G. Hicks, P.E., Nicholas P. Chopey 3.15. *LIQUID-LIQUID SEPARATION ANALYSIS

Source:

Inputs Liquid1 Volumetric Flow Rate Liquid1 Density Liquid2 Volumetric Flow Rate Liquid2 Density Time required for settling

11.4 59 70.4 52 108

gal/min lb/ft3 (Light) gal/min lb/ft3 (Heavy) min

Liquid Holdup Volume Liquid1 Mass Flow Rate Liquid2 Mass Flow Rate Holdup Volume Separator Tank Volume Separator Tank volume to holdup Volume Ration Tank Volume

5388 lb/hr 29416 lb/hr 15215 gal 1.2 Usual design practice is to make the separator tank volume 10 to 25% greater than the required holdup volume 18258 gal 2441 ft3

Size the Separator Tank Height to Diameter Ratio Tank Diameter Tank Height Tank Volume

5.00 8.53 ft 42.67 ft

Use goal seek to set Tank Volume equal to Holdup Volume by changing the Tank diameter

2441 ft3 18259 gal

Liquid depth in the Tank Liquid depth in the Tank Height of heavy liquid over flow

35.56 ft Assume that the two liquids interface midway between the vessel bottom and the Liquid surface 17.779 ft 37.82 ft

Height of heavy liquid Height of heavy liquid over flow Piping Arrangment

Velocity in pipe 6 ft/sec Feed flow rate 0.182445055 ft3/sec Cross Area of Pipe 0.030407509 ft2 Pipe diameter 0.196763927 ft 2.361167128 in Take the position of the interface as half-way up the Vessel and the light liquid off take as at 90% of the vessel height 50% Height from datum to light liquid overflow 21.33581855 ft Height from datum to heavy liquid overflow 21.33581855 ft Height from datum to the interface,m 21.33581855 ft Proposed design

37.818

Heavy Liquid Take-off #####

Light Liquid Take-off

42.67

8.53