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Sample Problem Statement

Flow rate of water = 18 m3/hr Entrained Flow of fuel gas = 100 m3/hr 

Operating pressure of separator = 0. barg !near atmospheri"#Separation effi"ien"$ re%uired is to remo&e water droplets abo&e the si'e of 10 mi"rons.Fuel gas properties "an be appro(imatel$ ta)en as properties of ethane.

Step 1

For fuel gas properties*+ole"ular weight of ethane = 30 gm/gmole

Step ,he gas li%uid separation "an be modeled using Sto)es law. -here gas bubble terminal &elo"it$ is e(presse

,he subs"ripts and stand for li%uid phase and &apour phase respe"ti&el$. nd the gas bubble diameter p is des"ribed in mi"rons.,hus* using p = 10 mi"ron*

2ere e$nolds number is "al"ulated below*

 s e 4 Sto)es law is &alid.

Step 3

Step 5

6e(t the &essel diameter "an be "al"ulated based on the allowable gas phase design &elo"it$ &alue obtaine,he terminal &elo"it$ for gas phase "an be e(pressed as*

2en"e*

7onsidering the / ratio re%uirement*

esign a &erti"al gasli%uid separator or a 9no") Out rum for separation of li%uid droplets entrained in fuel be "onsidered to be mostl$ ethane.

Operating temperature of separator = : 07

-ater densit$ at : 07 = ;;5.< )g/m3-ater &is"osit$ at : 07 = 0.; "P

Fuel gas densit$ at : 07 = 1.5: )g/m3Fuel gas &is"osit$ at : 07 = 0.00; "P

V t   = 0.0078 m/s

(It should be noted that the use of Stokes law is valid only for Reynolds number lower than 2.En

  tentati&e 2/ ratio needs to be fi(ed for the &essel. Sin"e the diameter of &essel !# and ,, height of tbetween then in the form of 2/ ratio. 6ormall$ this ratio &aries from 3 to :. 2ere we sele"t 3.:.

>t = 5?>g/!300?@d#... where >g is gas &olumetri" flow !m3/hr# and AdA is &essel diameter 

d = B>g/!;00?@?>t#

d = B100/!;00?@?0.00<8# = .13 m

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= 3.: ? .13 = <.5: m 'his length has to be checked to be compliant with proect speci)cation of li%uid residence tim