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Jacketed Vessel Design

Nov 08 2010 01:20 PM | Guest in Heat Transfer ***** Share this topic:
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Half Pipe Coil Jackets

jacketed_vessel_design4
Figure 4: Half Pipe
Coil Jacket

Half pipe coils provide high velocity and turbulence. The velocity can be closely controlled to achieve a good film coefficient. The good heat transfer rates, combined with the structural rigidity of the design, make half-pipe coils a good choice for a wide range of applications. A good design velocity for liquid utilities is 2.5 to 5 ft/s.

The maximumspacing between coils should be limited to 3/4". Half-pipe coils are ideally suited for high temperature applications where the utility fluid is a liquid.

There are no limitations of the number of inlet and outlet nozzles, so the jacket can be divided in multipass zones for maximum flexibility. The rigidity of the half-pipe coil design can also minimize the thickness of the inner vessel wall which can be especially attractive when utilizing alloys.

Half-pipe coil jackets are not covered in Section VIII, Division I of the ASME code. Generally, they are limited to 600 psig design pressure and a design temperature up to 720 °F. A carbon steel half-pipe jacket can be applied to a stainless steel vessel up to 300 °F. Over 300 °F, the jacket should be stainless steel as well.

Heat Transfer Coefficients: Half-Pipe Coil Jackets

Half-pipe coil jackets are generally manufactured with either 180° or 120° central angles (Dci):

jacketed_vessel_design13
Figure 5: Depiction of Center Angles
jacketed_vessel_design5
Figure 6: Half-Pipe Coil
to Tank Details

For a 180° central angle:

Equivalent Heat Transfer Diameter, De = Π / (4 Dci)

Cross Section Area of Flow, Ax = Π / (8 (Dci2))

For a 120° central angle:

Equivalent Heat Transfer Diameter, De = 0.708 Dci

Cross Section Area of Flow, Ax = 0.154 (Dci2)

Using the same nomenclature as previous, the heat transfer coefficients are calculated as follows:

hj De/ k= 0.027(NRe)0.8 (NPr)0.33 (µ/µW)0.14 (1+3.5 (Dc/De) ) (For NRe>10,000)Eq. (7)
hj De/ k = 1.86 [ (NRe) (NPr) (Dc/De) ] 0.33 (µ/µW)0.14 (For NRe<2,100)Eq. (8)

Do not confuse Dci with Dc. Dc is defined as Dji + ((Djo-Dji)/2).

Hydraulic Radius: Half-Pipe Coil Jackets

jacketed_vessel_design6
Figure 7: Hydraulic Radius
Dimensions

Referring to Figure7:

jacketed_vessel_design15

Eq. (9)





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2 Comments

Very useful guidance for designing Jacketed vessel. Thank you for your sharing.

thank you, but i have an situation here i already fabricated double jacket tank half pipe but i need another type of jacket to prevent marks of welding on the inner tank walls. kindly see below picture

http://postimg.org/image/4xhiuehkn/

http://postimg.org/image/ctl1tbqt3/

http://postimg.org/image/5cgfruqnr/

 

cloud you please advise