Chemical & Process Technology

Sunday, December 27, 2009

Calculate Wetted Surface Area For VERTICAL Cylindrical vessel with Elliptical Head

This post is in response to some readers request for calculation of Wetted Surface Area For VERTICAL Cylindrical vessel with Elliptical Head.

Earlier post "Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head" has presented an accurate equation may be used to calculate wetted surface area for Horizontal Cylindrical Vessel with Elliptical Head. Simplified equations also presented in "Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head (Simplified)"

to calculate the wetted surface area.

This principle in deriving Wetted Surface Area For VERTICAL Cylindrical vessel with Elliptical Head was based on the accurate equations as presented in "Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head". Two main principles used were :

horizontal vessel liquid height (H) reached maximum level (d) where H = d
horizontal vessel tan-tan length (L) equal to the vessel vessel liquid height ( l) where L = l

Wetted Surface Area (Cylindrical section)
Wetted Surface Area for Cylindrical section can be calculated with following equation :

Wetted Surface Area (Elliptical head)
Wetted Surface Area for Elliptical head (one head) can be calculated with following equation :

where
d = Vessel inside diameter (m)
l = Liquid height from bottom tangent line (m)

Example

An ellipsoidal heads VERTICAL vessel with internal diameter (d) of 1m and liquid level height from bottom tangent line is 2m. Determine wetted surface area.

d = 1m

l = 2m
Awet,Cyl = PI x d x l = PI x 1 x 2 = 6.28 m2
Awet,Head = 1.084 x d^2 = 1.084 x 1^2 = 1.084 m2
Total wetted surface area, Awet,total = Awet,Cyl + Awet,Head = 7.37 m2

Ref : "Accurate Wetted Areas for Partially Filled Vessels", by Richard C. Doane, "Chemical Engineering", December 2007
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Labels: Area, Fire

posted by Webworm, 8:39 AM | link | 0 Comments |

Saturday, April 11, 2009

Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head (Simplified)

Earlier post "Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head" has presented an accurate equation may be used to calculate wetted surface area for Horizontal Vessel with Elliptical Head. This post will presented a simplified equation to calculate the wetted surface area. Compare to accurate presented earlier, the difference is within 2%.

Let take the same sketch and example used in earlier post... :
A horizontal pressure vessel with radius R and length L (tan-tan) with liquid height of H, the wetted surface area can be the total wetted surface area of cylindrical section and elliptical head (2 heads).

Wetted Surface Area (Cylindrical section)
Wetted Surface Area for Cylindrical section can be calculated with following equation :

Wetted Surface Area (Elliptical head)
Wetted Surface Area for Elliptical head (one head) can be calculated with following equation :

where
R = Vessel inside radius (m)
H = Liquid height from bottom (m)
L = Vessel tangent-to-tangent length (m)

Example

An ellipsoidal heads horizontal vessel with internal diameter (D) of 3m and tangent-tangent length is 6m. Determine wetted surface area when maximum liquid level is at 1m above vessel bottom.

L = 6m
R = D / 2 = 1.5m
Awet,Cyl = 2LRxAcos[(R-H)/R]
Awet,Cyl = 2x6x1.5xAcos[(1.5-1)/1.5]= 22.16 m2
Awet,Head = [2.178 / (2 x 3.141592654)]x(2x1.5)^2 x Acos[(1.5-1)/1.5] = 3.84 m2
Total wetted surface area, S = Scyl + 2 x Shd = 29.84 m2

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Above equations have been programmed by Ankur & Kenny, share with readers of Chemical and Process Technology. You may download here.

Thanks to Ankur & Kenny
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Labels: Area, Fire

posted by Webworm, 3:09 PM | link | 0 Comments |

Thursday, April 9, 2009

Calculate Wetted Surface Area For Horizontal Vessel With Elliptical Head

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Fire relief estimation for two phase gas liquid in horizontal pressure vessel, wetted surface area is required to estimate total heat input into the horizontal pressure vessel. A horizontal pressure vessel with radius R and length L (tan-tan) with liquid height of H, the wetted surface area can be the total wetted surface area of cylindrical section and elliptical head (2 heads).

Wetted Surface Area (Cylindrical section)
Wetted Surface Area for Cylindrical section can be calculated with following equation :

Wetted Surface Area (Elliptical head)
Wetted Surface Area for Elliptical head (one head) can be calculated with following equation :

where
R = Vessel inside radius (m)
H = Liquid height from bottom (m)
L = Vessel tangent-to-tangent length (m)
e (epsilon) = Eccentricity (0.866 for 2:1 Ellipsoidal head)
F = Fraction Liquid Level, = H / 2R

Example

An ellipsoidal heads horizontal vessel with internal diameter (D) of 3m and tangent-tangent length is 6m. Determine wetted surface area when maximum liquid level is at 1m above vessel bottom.

L = 6m
R = D / 2 = 1.5m
F = H / 2R = 1 / (2 x 1.5) = 0.333
A = F - 0.5 = 0.333 - 0.5 = -0.167
B = SQRT[1+12A^2] = SQRT[1+12x(-0.167)^2] = 1.1547
Awet,Cyl = 2LRxAcos[(R-H)/R]
Awet,Cyl = 2x6x1.5xAcos[(1.5-1)/1.5]= 22.16 m2
Awet,Head = (PIxR^2/2)x[AxB+1+1/(4e)xLn[((4exA)+B)/(2-3^0.5)]=3.64 m2
Total wetted surface area, S = Scyl + 2 x Shd = 29.43 m2

Ref : "Accurate Wetted Areas for Partially Filled Vessels", by Richard C. Doane, "Chemical Engineering", December 2007

**********************************

Above equations have been programmed by Ankur, a experience Chemical Engineer, share with readers of Chemical and Process Technology. You may download here.

Thanks to Ankur
Download

*If you have any useful program and would like to share within our community, please send to me.

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