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 of CHE 352

Spring Semester, 2014 Arizona 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 Balaraman A2 02/17/2014

Table of Contents Page Abstract ............................................................................................................................................ i Introduction/background/theory .....................................................................................................1 Materials and apparatus/procedure, ................................................................................................4 Results .............................................................................................................................................6 Discussion/conclusion/recommendations ......................................................................................10 References ......................................................................................................................................11 Appendix A: (title of Appendix A) ................................................................................................12

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

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

List of Terms Density (kg/m3) ............................................................................................................................................. ρ Superficial Velocity (m/s)………………………………………………………………………………....μ0 Reynolds number (Dimensionless) …………………………………………………………....................Re Length (m)…………………………………………………………………………………………………L Void Fraction (Dimensionless) ……………………………………………………………………………Ɛ Viscosity (Dimensionless) (kg/ms)………………………………………………………………………...μ Effective Diameter (m)…………………………………………………………….……………………...Dp Volumetric flow rate…………………………………………………………………………...............…Q Gallons per minute (1/min)……………………………………………………………………………...gpm Pressure Drop (kPa)……………………………………………………………………………...............Δp Friction Factor (Dimensionless)…………………………………………………………………………..f

printed 3/2/2014

Balaraman_Flow Through Packed Columns.doc  Document1

p. 1



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

printed 3/2/2014


p. 2



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

printed 3/2/2014


p. 3



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

printed 3/2/2014


p. 4



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.

printed 3/2/2014


p. 5



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

printed 3/2/2014


p. 6



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

Pressure Difference (kPa)

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

140 120 100 80 60 40 20 0 0

0.2

0.4

0.6

0.8

Flow rate (GPM)

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.

printed 3/2/2014


p. 7



40 P1

P2

35

Pressure KPa

30 25 20 15 10 5 0 0

0.5

1

1.5 2 Flow Rate (GPM)

2.5

3

3.5

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.

printed 3/2/2014


p. 8

Pressure Drop (kPa/s )



140

Theoretical Value

120

Experimental Value

100 80 60 40 20 0 0

0.01

0.02

0.03

0.04

0.05

0.06

Superficial Velocity (m/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 .

printed 3/2/2014


p. 9


10000

25/45 Mesh Glass Sphere 1/8 in Plastic Sphere Ergun Equation

1000

log (fp)


100

10

1 0.1

1

10

100

1000

10000

log(Rn) 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.

printed 3/2/2014


p. 10



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.

printed 3/2/2014


p. 11



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

printed 3/2/2014


p. 12

Appendix A


Appendix A: (Measured Data and Calculated Data ) Table 1 : Pressure Data collected for 25/45 Mesh Glass sphere Rotameter Input Pressure Out Put Pressure Readibg(GPM) (kPa) (kPa) 0.2 21.6 1.12 0.3 37.2 1.28 0.4 54.5 1.48 0.5 74.17 1.73 0.6 90.4 1.93 0.7 118.75 2.3

Change in Pressure (kPa) 20.48 35.92 53.02 72.44 88.47 116.45

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

Fluid Dp (Spherical diameter ) (m) Density of the Particle (Kg/m^3) Ɛ Pipe Circumference (m) Column Radious (m) Cross-sectional area (m^2) Diameter Ratio Viscosity (kg/ms) Density (kg/m^3) Height (m)

printed 3/2/2014

25/45 Mesh-Glass sphere

1/8'' Plastic sphere (150 gm)

0.00031

0.00039

1200 0.1691 0.1025 0.01632 0.000836

2500 0.6012 0.1575 0.02508 0.00196

0.01899

0.0156

0.18

0.16

0.001 997.08


p. 13


Table 3 : Data Calculated from 25/45 Glass sphere Dimensionless Pressure (fp) and Reynolds number ΔP/L fp Flow Rate Change in Superficial Reynolds (m^3/s) Pressure (kPa) velocity(m/s) Number 1.2618E-05 20.48 0.01508 5.61147 113777.8 0.9047 1.89271E-05 35.92 0.02266 8.41619 199555.6 0.7052 2.52361E-05 53.02 0.03019 11.2215 294555.6 0.5855 3.15451E-05 72.44 0.03771 14.0263 402444.4 0.5120 3.78541E-05 88.47 0.04525 16.8336 491500 0.4342 4.41631E-05 116.45 0.05279 19.6377 646944.4 0.41993

Table 4 : Pressure data collected for the columns with 1/8'' Plastic Spheres Rotameter Reading Input Pressure (GPM) (kPa) Output Pressure (kPa) 0.2 1.24 0.99 0.3 1.55 1.08 0.4 1.96 1.23 0.5 2.37 1.37 0.6 2.85 1.57 0.7 3.5 1.81 1 5.75 2.69 1.5 10.66 4.68 2 17.45 7.53 3 37.8 16.1

printed 3/2/2014

Balaraman_Flow Through Packed Columns.doc)  Document1

Change in Pressure (Kpa) 0.25 0.47 0.73 1 1.28 1.69 3.06 5.98 9.92 21.7


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 ΔP/L fp Superficial Reynolds (kPa) velocity (m/s) Number 1.2618E-05 0.25 0.00638 6.22909 1562.5 8.1563 1.89271E-05 0.47 0.00956 9.34364 2937.5 6.8152 2.52361E-05 0.73 0.01277 12.4581 4562.5 5.9544 3.15451E-05 1 0.01597 15.5727 6250 5.2202 3.78541E-05 1.28 0.01916 18.6872 8000 4.6402 4.41631E-05 1.69 0.02236 21.8018 10562.5 4.5012 6.30902E-05 3.06 0.03194 31.1454 19125 3.9930 9.46353E-05 5.98 0.04791 46.7182 37375 3.4685 0.00012618 9.92 0.06388 62.2909 62000 3.2369 0.000189271 21.7 0.09583 93.4364 135625 0.00972

printed 3/2/2014



Post-Reflection Experiment #___: (title) Full technical laboratory/research report (put post-reflection work here)

printed 3/2/2014


Flow Through Packed Lab report for chemical engineering

Recommend Documents