Flooding Velocity in Vertical Shell and Tube Condensers

Use this calculation procedure to calculate the minimum flooding velocity in a verticallymounted shell and tube condenser.

This procedure includes helpful worksheets to obtain the necessary physical propertiesfor the calculation as well as heat exchanger tube data.

The spreadsheet includes both english and metric units.

Do not rename sheets in this workbook

Sheets are protected, but protection may be turned off.

Revision History :12/31/2003 - Vapor Density worksheet was using standard temperatures in error.

Worksheet changed to reflect the use of absolute temperatures.

This spreadsheet is copyright 2002, The Chemical Engineers' Resource Page, www.cheresources.com. The information contained herein may not be retransmitted, copied, or electronically posted without the expressed written consent of The Chemical Engineers' Resource Page. You may use this spreadsheet for personal or professional use only. Cheresources, Inc. and it's associates can not be held responsible for the results obtained from this program. Good engineering judgement should always be exercised in using this or any other software.

Flooding Velocity in Vertical Shell and Tube Condensers

Applicable to: Vertically oriented shell and tube condensers with upflow vapors on the tubeside

Assumption of Method:--Methods used are based on correlations derived from experimental data--Actual vapor velocity calculated is the velocity at the tube entrance

Calculation Details:

Begin by defining the physical properties of the fluids in the system.

Define the liquid density at the condensing temperature:57

Define the vapor density at the condensing temperature and pressure:0.9

Define the surface tension of the liquid:28 dynes/cm

Define the liquid viscosity at the condensing temperature:0.33 cP

Next, identify the heat exchanger geometry:

Number of Tubes = 2000.732 in

= 0.58449

Identify the mass flow rates at the end of the exchanger:Liquid Mass Flow Rate = 2500 lb/h (condensate flow out of exchanger)Vapor/Gas Mass Flow Rate = 5000 lb/h (vapor flow into exchanger)**For total condensation, enter "1" here --> (for partial condensation, leave blank)*** Vapor flow into exchanger must be larger than or equal to the condensate flow out of the exchanger

Choose tube end style: Square End (standard tubes)Cut tubes can result in a significant increase in the Cut Tubes (below)maximum allowable floodingvelocity:

% increase in allowableAngle gas flow rate30° 560° 2570° 55

rL = lb/ft3 Liquid Density Worksheet

rV = lb/ft3 Vapor Density Worksheet

s = Surface Tension Worksheet

mL = Liquid Viscosity Worksheet

Inside Diameter (Di) = Tube Data Lookup Chart

Ax ft2

NomenclaturerL= liquid density (lb/ft3)rV= vapor density (lb/ft3)s = liq. surface tension (dynes/cm)mL= liquid viscosity (cP)Di = tube inside diameter (in)Ax = cross sectional area (ft2)ML = liquid mass flow rate (lb/h)MV = vapor mass flow rate (lb/h)q = tube cut angle (degrees)Vflood = flooding velocity (ft/s)Vactual = actual vapor velocity (ft/s)

References:Alekseev and English, et.al, presented by ESDU, "Reflux Condensation in Vertical Tubes", Data Item 89038, 1989.HEDH, page 2.6.2-7

q = 60 ° (only needed for cut tubes)

Flooding Velocity in Vertical Shell and Tube Condensers

Applicable to: Vertically oriented shell and tube condensers with upflow vapors on the tubeside

Assumption of Method:--Methods used are based on correlations derived from experimental data--Actual vapor velocity calculated is the velocity at the tube entrance

Calculation Details:

Begin by defining the physical properties of the fluids in the system.

Define the liquid density at the condensing temperature:880

Define the vapor density at the condensing temperature and pressure:14.4

Define the surface tension of the liquid:28 dynes/cm

Define the liquid viscosity at the condensing temperature:0.33 cP

Next, identify the heat exchanger geometry:

Number of Tubes = 20018.59 mm

= 0.05428

Identify the mass flow rates at the end of the exchanger:Liquid Mass Flow Rate = 2273 kg/h (condensate flow out of exchanger)Vapor/Gas Mass Flow Rate = 2273 kg/h (vapor flow into exchanger)**For total condensation, enter "1" here --> 1 (for partial condensation, leave blank)*** Vapor flow into exchanger must be larger than or equal to the condensate flow out of the exchangerLiquid Mass Flow Rate should equal Vapor/Gas Mass Flow Rate

Choose tube end style: Square End (standard tubes)Cut tubes can result in a significant increase in the Cut Tubes (below)maximum allowable floodingvelocity:

% increase in allowableAngle gas flow rate30° 560° 2570° 55

rL = kg/m3 Liquid Density Worksheet

rV = kg/m3 Vapor Density Worksheet

s = Surface Tension Worksheet

mL = Liquid Viscosity Worksheet

Inside Diameter (Di) = Tube Data Lookup Chart

Ax m2

References:Alekseev and English, et.al, presented by ESDU, "Reflux Condensation in Vertical Tubes", Data Item 89038, 1989.HEDH, page 2.6.2-7

NomenclaturerL= liquid density (kg/m3)rV= vapor density (kg/m3)s = liq. surface tension (dynes/cm)mL= liquid viscosity (cP)Di = tube inside diameter (mm)Ax = cross sectional area (m2)ML = liquid mass flow rate (kg/h)MV = vapor mass flow rate (kg/h)q = tube cut angle (degrees)Vflood = flooding velocity (m/s)Vactual = actual vapor velocity (m/s)

q = 65 ° (only needed for cut tubes)

Shell and Tube Heat Exchanger Tube Data

Outside Diameter BWG Wall Thick. Inside Diameter Inside Cross Sectional Areain. mm Number in. mm in. mm1/2 12.7 12 0.109 2.77 0.282 7.16 0.000434 0.4030

14 0.083 2.11 0.334 8.48 0.000608 0.565316 0.065 1.65 0.370 9.40 0.000747 0.693718 0.049 1.24 0.402 10.21 0.000881 0.818920 0.035 0.89 0.430 10.92 0.001008 0.9369

5/8 15.88 12 0.109 2.77 0.407 10.34 0.000903 0.839414 0.083 2.11 0.459 11.66 0.001149 1.067516 0.065 1.65 0.495 12.57 0.001336 1.241618 0.049 1.24 0.527 13.39 0.001515 1.4073

3/4 19.05 12 0.109 2.77 0.532 13.51 0.001544 1.434114 0.083 2.11 0.584 14.83 0.001860 1.728216 0.065 1.65 0.620 15.75 0.002097 1.947818 0.049 1.24 0.652 16.56 0.002319 2.1540

1 25.4 10 0.134 3.40 0.732 18.59 0.002922 2.715112 0.109 2.77 0.782 19.86 0.003335 3.098614 0.083 2.11 0.834 21.18 0.003794 3.524416 0.065 1.65 0.870 22.10 0.004128 3.8353

1 1/4 31.75 10 0.134 3.40 0.982 24.94 0.005260 4.886312 0.109 2.77 1.032 26.21 0.005809 5.396614 0.083 2.11 1.084 27.53 0.006409 5.954116 0.065 1.65 1.120 28.45 0.006842 6.3561

1 1/2 38.1 10 0.134 3.40 1.232 31.29 0.008278 7.690912 0.109 2.77 1.282 32.56 0.008964 8.327914 0.083 2.11 1.334 33.88 0.009706 9.0171

2 50.8 10 0.134 3.40 1.732 43.99 0.016362 15.200312 0.109 2.77 1.782 45.26 0.017320 16.0906

Return to English Units Return to Metric Units

ft2 m2 x 104

Liquid Density Calculation Worksheet

1. For pure fluids, check the If your fluid is not listed, consult one of many good source in print or online.

2. For mixtures, use a weighted average of the liquid densities of each component:=

Mass Fractions Liquid Densities Weighted Densities0.2 62 12.40.1 95 9.50.3 55 16.50.5 58 29

00

67.4 Estimated Mixture Density

Return to English UnitsReturn to Metric Units

table below

rmix S xi ri

Vapor Density Calculation Worksheet

1. For pure vapor below 10 bar or 150 psi, employ the ideal gas law:English Units

P (MW) = 25.5 psia 85 lb lb-mole °RR T lb-mole 11 250 °R

* °R = °F + 459.7= 0.808 250 °F = 709.7

Metric Units

P (MW) = 1.8 bar 85 g mol KR T mol 0.08 L bar 120 K

* K = °C + 273.15= 15.336 g / L 300 °C = 573.15

2. For pure vapors above 10 bar or 150 psi, employ the Redlick-Kwong relationship to calculate the compressibility:

where:A = 0.4278 Pr and B = 0.08664 Pr

TrTr = T / TcPr = P / Pc

English UnitsTc = 455.36 °F Operating Temperature = 600 °F

Pc = 734.8 psia Operating Pressure = 100 psia

Tr = 1.15807 °R Pr = 0.136091 psia

A = 0.040340 B = 0.010182

Z = ### Solver Cell = 0.010 (set equal to zero)If you have Solver installed, press "Ctrl+s" to solve

Then, compressibility can be added to the gas equation for improved accuracy:

P (MW) = 100 psia 85 lb lb-mole °RR T Z lb-mole 11 1059.7 °R 0.980

= 0.763

Return to English UnitsReturn to Metric Units

rvap =ft3 psia

lb / ft3

rvap =

or kg / m3

Z3 - Z2 + (A-B-B2) Z - AB = 0

Tr2.5

Lookup Chart for Critical Temperatures and Pressures

rvap =ft3 psia

lb / ft3

Metric UnitsTc = 235.2 °C Operating Temperature = 200 °C

Pc = 50.6 bara Operating Pressure = 20 bara

Tr = 0.930756 K Pr = 0.395257 bara

A = 0.202316 B = 0.036793

Z = ### Solver Cell = -0.032 (set equal to zero)If you have Solver installed, press "Ctrl+d" to solve

Then, compressibility can be added to the gas equation for improved accuracy:

Metric Units

P (MW) = 20 bar 85 g mol KR T Z mol 0.08 L bar 473.15 K 0.729

= 59.3 g / L

3. For vapor mixtures where the density is not known consult the following online calculation which utilizes Peng-Robinson:

If one or more of your components are not available in the component list at this site, you may have to utilize another EOS along with Kay's method andgeneralized compressibility charts.

Lookup Chart for Critical Temperatures and Pressures

rvap =

or kg / m3

http://www.questconsult.com/~jrm/thermot.html

Liquid Surface Tension Calculation Worksheet

1. For pure liquids, check the following source of online data:

(Download PhysProps)

If you still cannot find the data that you need, email support at:

and request the following parameters for your chemical:A = 132.674 Default data is ConversionTc = 647.13 K for water 54 °C = 327 Kn = 0.955 100 °F = 311 K

Then enter the temperature of your system = 298.15 K

Surface Tension = 73.56 dynes/cmPlease refer to "Chemical Properties Handbook", page 216 with your request.

employ the following to estimate the surface tension for the mixture:

where:surface tension of the mixture (dynes/cm) Density Conversion:

58.5 lb/ft3 = 0.93708mole fraction for each componentsurface tension of each component (dynes/cm)

Enter the data below, employing the units described above:Components Mole Fractions Component Surface Tensions Component Liquid Densities

1 Benzene 0.577 28.23 0.87222 Diethyl Ether 0.423 16.47 0.70693456

Enter the mixture liquid density = 0.7996

= 1.52489

= 1.20547 22.72 dynes/cm= 0= 0 This method is best for mixtures that are = 0 soluble in one another. It assumes that the = 0 surface of the liquid will act like the bulk of

Return to English UnitsReturn to Metric Units

http://www.cheric.org/kdb/index.htmlhttp://gpengineeringsoft.com/pages/products.html

support@cheresources.com

2. If your system is a mixture of organic compounds and does not contains water,

sm1/4 = rLm S((xi si

1/4) / rLi)

sm =rLm = liquid density of the mixture (g/cm3) g/cm3

xi =si =rLi = liquid density for each component (g/cm3)

g/cm3

((x1 s11/4) / rL1)

((x2 s21/4) / rL2) sm =

((x3 s31/4) / rL3)

((x4 s41/4) / rL4)

((x5 s51/4) / rL5)

((x6 s61/4) / rL6)

2.73035 the liquid.

estimate from support or reference the following:

4. If your system contains water and multiple other components, consult a process simulator or a knownreliable model for your fluid. These types of systems are best suited to experimentation.

3. If your system contains water and one other component, request a surface tension

"Properties of Gases and Liquids" by Reid, et. Al, page 648support@cheresources.com

Liquid Viscosity Calculation Worksheet

1. For pure fluids, lookup the constant values on the below and enterthem into the following calculation:

ConversionSystem Temperature = 373 K 100 °C = 373 KConstant B = 658.23 100 °F = 311 KConstant C = 283.16

Default constants are for water (B=658.25, C=283.16)Liquid Viscosity = 0.275 cP

This method is best for saturated liquids.

If your liquid is not shown in the list below, consult the following online source:

2. For liquid mixtures, there has been much experimental work performed and the error levelfor most of these correlations does not justify the complexity of their use for a propertythat can be easily measured. If measurements are not available, utilize the following estimate for the properties of the mixture:

This method assume that the components are soluble in one another.

Mole Fraction Viscosity of ComponentComponent in Process Stream at System Pressure (cP)

1 Benzene 0.6 0.6082 Toluene 0.4 0.5583456

-0.29855-0.23336

0 0.587 cP000

-0.53191

Return to English Units

Return to Metric Units

Table

http://www.cheric.org/kdb/index.html

LN mmix = x1 LN m1 + x2 LN m2 + ...

x1 LN (m1) =x2 LN (m2) =x3 LN (m3) = mmix =x4 LN (m4) =x5 LN (m5) =x6 LN (m6) =