Flow Through Packed Lab report for chemical engineering

Flow Through Packed Columns

A Research Report Submitted by:Manukumar Balaraman

in partial fulfillment of the requirements ofCHE 352

Spring Semester, 2014Arizona State University

Chemical Engineering Program

Abstract

Object of this Technical lab report give a detail study of the characteristics of a packed columns (porous

media) with respect to pressure drop of certain point on the columns with different flow rates. Theory

behind this experiment is the Comparison of each columns pressure drop with respect to Ergun equation .

The experiment was done with two different packed columns one is filled with 25/45mesh-Glass sphere

and other is filled with 150 gm Plastic spheres ( similar to 1/8 inches plastic sphere), and water is use as a

fluid in the reactor. Five pressure reading are taken for each columns from two different point. Two

rotameters are used to maintained the different flow rate, the height of the porous media is recorded. In

this experiment seems to use of many equation and concept from the last year Fluid Mechanics class . The

resulting data is plotted as a log-log function of dimensional pressure and Reynolds number ,this plot

support the theory of Ergun’s equation. Theory is that dimensional pressure drop increase when the

Reynolds number increase.

Flow Through the Packed Columns Manukumar BalaramanA2

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Table of Contents

PageAbstract.............................................................................................................................................iIntroduction/background/theory .....................................................................................................1Materials and apparatus/procedure, ................................................................................................4Results .............................................................................................................................................6Discussion/conclusion/recommendations......................................................................................10References......................................................................................................................................11Appendix A: (title of Appendix A)................................................................................................12

List of Figures

PageFigure 1 (Basic setup of a Pack Bed Columns).............................................................................................4Figure 2 (Change in Pressure with the Flowrate for 25/45 mesh Glass sphere columns)……………..…...6Figure 3 (Inlet and Outlet Pressure of 1/8 inches Plastic sphere columns)……………………...................7Figure 4 (Theoretical pressure drop versus experimental with respect to superfical velocity)…................8Figure 5 (Comparison of experimental Dimensionless pressure with Ergun’s equation)……….................9

List of Tables

PageTable 1 (Pressure data collected for 25/45 mesh glass sphere)....................................................................12Table 2 (Constant and Variable parameter of water and media at STP)......................................................12Table 3 (Data collected for 25/45 glass sphere dimensionless pressure drop and Re)…………………....13Table 4 (Pressure data collected for columns with 1/8 inches plastic sphere)…………………................13Table 5 (Calculated value for Dimensionless pressure and Re for 1/8 inches plastics sphere)…………...14

List of Terms

Density (kg/m3)..............................................................................................................................................ρSuperficial Velocity (m/s)………………………………………………………………………………....μ0

Reynolds number (Dimensionless) …………………………………………………………....................ReLength (m)…………………………………………………………………………………………………LVoid Fraction (Dimensionless) ……………………………………………………………………………ƐViscosity (Dimensionless) (kg/ms)………………………………………………………………………...μEffective Diameter (m)…………………………………………………………….……………………...Dp

Volumetric flow rate…………………………………………………………………………...............…QGallons per minute (1/min)……………………………………………………………………………...gpmPressure Drop (kPa)……………………………………………………………………………...............ΔpFriction Factor (Dimensionless)…………………………………………………………………………..f

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Introduction / Background / Theory

Most chemical processing industry use packed column to exchange the heat and mass transfer.

Packed columns is a kind of packed bed reactor .Study of pack bed is important now a days, because its

theory has a wide verity of application . main attraction is it low maintenance cost and low energy

conception.Most of chemical separation are carried out through the packed columns like

absorption ,distillation ,extraction ,stripping etc and also used in combustion too. Study of the pressure

drop lead for stepping stone of many application such a pump designing ,process optimization that lead

to cost effectiveness .the concept of Pack bed often used for controlling greenhouse gas production , for

example it is used in the waste stream for scribe H2s gas going out to air and also used in automobile for

Catalytic converter .The important application is the water purification .In the pack bed , packing done

with different kind of material like ceramics, glass sphere ,plastic sphere marbles and active carbon and

also with sand too. The advantage of the packed columns is the packing material it increase the surface

area of the contacting phases, that help to transfer heat or mass from one phase to another2.

This report explain the characteristic and function of a pack bed reactor by calculating the

pressure drop when a fluid passed through different submerged porous media at different flow rate.

When the fluid flow is zero that is no flow through the packed bed then the net gravitation force acting

downwards. When fluid is flowing through the columns then the upwards frictional force of the fluid is

counter balance the gravitational forces. Our focus in this lab is to measure the pressure difference in each

columns with two different type of porous material used as packing the columns. The pressure drop of

the fluid flowing through the system accompanying by lose of kinetic and viscous energy .the factors

determining this energy lose are fluid flow, density of the fluid and viscosity of the fluid ,shape and size

of the porous media1.

After taking the pressure difference in different fluid flow we can compare the measured data

with Ergun equation and make a log-log plot with dimensionless pressure versus the Reynolds number



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because pressure drops is a depended variable and the Reynolds number is a independent variable . There

are several approaches are describing the flow through the packed bed and most successful is Ergun

equation. This equation describe both type of fluid flow that is turbulent and laminar . The main reason

for the ergun equation is good to predict the pressure drop because this equation is not only depend on the

pressure drop of the fluid but also it account other factors too like particle packing

density ,shape ,uniformity and fluid properties such as viscosity etc and he also account for void fraction

and sphericity of the porous media. Ergun equation as follows3

(Equation#1)

There are number of theory help Ergun to derive this equation for example Reynolds number ie

Osborne Reynolds observed the friction in the pack bed is due to properties of fluids and packing and also

the following two equation are basis of the Ergun’s equation one is Carman-Kozeny equation for the

viscous flow and Burke-Plummer equation for turbulent flow1.

Carman- Kozeny equation

(Equation#2)

Burke-Plummer equation1

(Equation#3)

Where Δp is the pressure drop ,L is the length of the Bed, Dp Spherical diameter of the particle of the

packing , ρ is the density of the fluid, μ viscosity of the fluid,V0 is superficial velocity,Ɛ is the void

fraction of the bed. Void fraction is the ration of the space unfilled by the packing ( Pack bed is not fully



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packed ) to the volume of the columns. if the fluid flow with low flow rate that is Reynolds is less than

2000 and if the flow is high and Reynolds number is greater than 4000 then that flow is called turbulent.

Equation for Reynolds number and friction for a packed bed and is as follows3.

(Equation#4)

(Equation#5)

The fp called the friction factor for the packed bed

Δp is the pressure drop

L is the length of the Bed

Dp Spherical diameter of the particle of the packing

ρ is the density of the fluid

μ viscosity of the fluid

Vs is superficial velocity

Ɛ is the void fraction of the bed



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Materials and Apparatus / Procedure

Figure 1: Basic setup of a Packed bed reactor1

In this setup there are four column filled with different packing materials and each column has separate

input and output valve. To control the fluid flow there is three different rotometer is used two GPM and

one is GPH ,in two GPM one is low flow rate rotameter and other is high flow rotameter. packing bed

column is connected to four small hose in the body of the column, through this hose we are calculating

the pressure reading .For reading pressure we have a electronic pressure gauge ,in the small hose there is

clamp connected this hold the fluid coming out of the small hose.



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Procedure

The experiment is doing with a packed column device located in the Lab. Before starting the pump exam

all valves and connection are properly secured and they are in correct position, once instructor is verify

the pre lab and granted permission for doing the experiment ,identify the packing material from data info

tag take the diameter of column to use the experiment and measure the height of the packing bed write

down all the data in to lab note book after completing these preliminary task we start actual lab

experiment. Then run the pump for a minute take out all trapped air bubbles from columns this help to

improve the data precision , because it may affect the pressure drops. Team chose two columns to take the

pressure drop with different flow rate set in the rotameter, one is packed with the 1/8 Plastic sphere (150

grams) and other is 25/45 mesh glass sphere of 150 grams. Start the water at low flow rate set the

rotameter with low value setting, start the first columns inlet and outlet valve open at the same time and

pressure is measured at each point with an electronics pressure reader (pressure reader need to calibrate

to atmospheric pressure this is done by pressing tare button in the pressure gauge) , change the random

water flow rate with as specific setting in rotameter and note the rotamete setting the lab note book ,there

are small hose in the column plugged with a clamp first connect the hose to the electronic pressure

reading meter and then clamp is realized then water will flow to the pressure reader and show the pressure

of the fluid in the reader display not the reading the book with respect to the flow rate .and take the

pressure reading of each flow rate. Collect pressure data for different rotameter setting that is different

fluid flow. Occasionally we can observer that air bubble will come in the hose then unscrew the

connection between the small hose and the pressure meter and allow to flow out some water from the

hose, this will avoid the trapped air bubbles from the system. Nature of the packing material is very

important for the characterization of packed columns. Repeat this experiment with other columns with

plastic sphere with 1/8 inch thickness for different flow rate and find the pressure drop



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Results

This experiment went well we take all required data with in time with out any major errors. calculation

are done by substituting the predefined value of density and viscosity of water at 250c .

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

20

40

60

80

100

120

140

Flow rate (GPM)

Pres

sure

Diff

eren

ce (k

Pa)

Figure 2: Change in Pressure with the Flow rate for 24/45 Mesh Glass sphere columns.

When we notice that there is an increase in pressure of difference in the 25/45 Mesh Glass sphere

columns with increase in flow rates. The pressure increase because the water is try to move fast with in

the small void space between the sphere.



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0 0.5 1 1.5 2 2.5 3 3.50

5

10

15

20

25

30

35

40P1 P2

Flow Rate (GPM)

Pres

sure

KPa

Figure 3:Inlet and Outlet Pressure of 1/8 inch plastic sphere column with different flow rates (P1-input pressure ,P2-output pressure )

As the flow rate increase the input pressure and output pressure are increase in the 1/8 inches plastic

sphere columns more pressure in the inlet this is because of water try to flow through the small void

between the 1/8 inches plastic sphere .so more pressure is creating the inlet than the out let. This figure

also give a comparison between the pressure difference between inlet and outlet of the packed bed

columns.



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0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.0550

20

40

60

80

100

120

140 Theoretical Value

Experimental Value

Superficial Velocity (m/s)

Pres

sure

Dro

p (k

Pa/s

)

Figure 4 : Theoretical pressure Drop versus the experimental Pressure drop value with respect to the superficial velocity in the 25/45 Mesh Glass sphere columns.

Figure 5 compare the theoretical pressure drop with re experimental value we obtain from the data

measured during the lab .theoretically the superficial velocity going down when the pressure going high

but in the experimental trends show that the when the superficial velocity is high the pressure is also

going high .



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0.1 1 10 100 1000 100001

10

100

1000

1000025/45 Mesh Glass Sphere1/8 in Plastic SphereErgun Equation

log(Rn)

log

(fp)

Figure 6: Comparison of Experimental Dimensionless Pressure with Ergun’s equation for both columns that is 1/8 inches Plastic Spheres and 25/45 mesh glass sphere.

A log-log scale used to show the experimental data value with theoretical ergun’s equation value , this is

because ergun equation correlate with Reynolds number.



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Discussion / Conclusion / Recommendations

For this experiment we choose two columns of the packed bed reactor two our experiment , this columns

are packed with two different materials, one is 25/45 mesh glass spheres column and other is 1/8 inch

plastic spheres column. Each sphere has different diameters and through this experiment we are trying to

find out the pressure drop which support the basic theory of ergun’s equation. That is the flow rate

increase as the pressure drop across the bed, as we seen in the figure 2 and figure 3 ,this is because of the

Reynolds number is directionally proportional to the flow rate. Trend in the pressure drop with ergun’s

equation is shown in the log-log figure that is when Reynolds number is increasing the pressure get

reduced that is the turbulent flow has reduced pressure than the laminar flow because laminar flow has

smaller Reynolds number . In conclusion this experiment is a huge success and we got all graph in a

proper shape and only thing make mistake is the calculation part . systematic error is a big factor in the

packed bed reactor experiment. Mistake can made while take the height of the bed or taking pressure

reading from the electronic device because it show two many up and down values for each time we

measure the reading that is reading Fluctuation from 5 kpa to 20 kpa, this was some air bubbles are

trapped in the hose and the columns, so we are always take two or more reading to make sure we got

accurate reading .So in future this is a good technique to avoid this type of systematic errors. And the

pressure reading equipment is old so it need to replace a new modern one . the rotameter using with

equipment is too out dated because of this we can’t get correct fluid flow rate .

After completing this experiment we got a good understanding about the theory we learned in the fluid

mechanics class. All got a deep understanding how the pressure change can apply different

applications ,and also by using ergon’s equation we understand how the theoretical and experimental

value can correlate each other.



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References

[1] Flow through the Packed Bed Reactors 1: Single Phase Flow . http://www.sciencedirect.com/science/article/pii/S000925090500x (accessed Februaru 14 ,2014)

[2] Geankpolis,C.J Transport process and Separation principles, 4th Edition 996-997,2010

[3] James.O.Wilkes , Fluid Mechanics for Chemical Engineers with Microfluid and CFD,Upper Saddle River .NJ:Prentice Hall Profesional Technical Reference 2006 page :204-207


http://www.sciencedirect.com/science/article/pii/S000925090500x

Appendix A Manukumar BalaramanA2

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Appendix A: (Measured Data and Calculated Data )

Table 1 : Pressure Data collected for 25/45 Mesh Glass sphere Rotameter

Readibg(GPM)Input Pressure

(kPa)Out Put Pressure

(kPa)Change in Pressure

(kPa)0.2 21.6 1.12 20.480.3 37.2 1.28 35.920.4 54.5 1.48 53.020.5 74.17 1.73 72.440.6 90.4 1.93 88.470.7 118.75 2.3 116.45

Table 2: Constant and Variable Parameters of the water and media at STP

Fluid25/45 Mesh-Glass

sphere 1/8'' Plastic sphere

(150 gm)

Dp (Spherical diameter ) (m) 0.00031 0.00039Density of the Particle

(Kg/m^3) 1200 2500Ɛ 0.1691 0.6012

Pipe Circumference (m) 0.1025 0.1575Column Radious (m) 0.01632 0.02508

Cross-sectional area (m^2) 0.000836 0.00196

Diameter Ratio 0.01899 0.0156Viscosity (kg/ms) 0.001Density (kg/m^3) 997.08

Height (m) 0.18 0.16


Manukumar BalaramanA2

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Table 3 : Data Calculated from 25/45 Glass sphere Dimensionless Pressure (fp) and Reynolds number Flow Rate

(m^3/s)Change in

Pressure (kPa)Superficial

velocity(m/s)Reynolds Number

ΔP/L fp

1.2618E-05 20.48 0.01508 5.61147 113777.8 0.90471.89271E-05 35.92 0.02266 8.41619 199555.6 0.70522.52361E-05 53.02 0.03019 11.2215 294555.6 0.58553.15451E-05 72.44 0.03771 14.0263 402444.4 0.51203.78541E-05 88.47 0.04525 16.8336 491500 0.43424.41631E-05 116.45 0.05279 19.6377 646944.4 0.41993

Table 4 : Pressure data collected for the columns with 1/8'' Plastic SpheresRotameter Reading

(GPM)Input Pressure

(kPa) Output Pressure (kPa)Change in Pressure

(Kpa) 0.2 1.24 0.99 0.250.3 1.55 1.08 0.470.4 1.96 1.23 0.730.5 2.37 1.37 10.6 2.85 1.57 1.280.7 3.5 1.81 1.691 5.75 2.69 3.06

1.5 10.66 4.68 5.982 17.45 7.53 9.923 37.8 16.1 21.7

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Table 5 : Measure the value for the dimensionless pressure and Reynolds number for the column with 1/8 ‘’ Plastic sphere

Flow Rate (m^3/s) Change in Pressure (kPa)

Superficial velocity (m/s)

Reynolds Number

ΔP/L fp

1.2618E-05 0.25 0.00638 6.22909 1562.5 8.15631.89271E-05 0.47 0.00956 9.34364 2937.5 6.81522.52361E-05 0.73 0.01277 12.4581 4562.5 5.95443.15451E-05 1 0.01597 15.5727 6250 5.22023.78541E-05 1.28 0.01916 18.6872 8000 4.64024.41631E-05 1.69 0.02236 21.8018 10562.5 4.50126.30902E-05 3.06 0.03194 31.1454 19125 3.99309.46353E-05 5.98 0.04791 46.7182 37375 3.46850.00012618 9.92 0.06388 62.2909 62000 3.23690.000189271 21.7 0.09583 93.4364 135625 0.00972



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Flow Through Packed Lab report for chemical engineering