Exchanger
1. Problem Statement & Scope of Work
Ethylbenzene is manufactured by alkylation of benzene with ethylene. The reaction
products are separated in a series of distillation columns. Ethylbenzene is obtained as
the distillate from the last column (called the ethylbenzene column). In a 70 ton per
day ethylbenzene plant, the final product leaves the overhead condenser at 1350C.
This is required to be cooled to 400C before pumping it to the storage tank. Cooling
water is available at 300C for cooling. Please provide a proposal for the design of a
multi-pass counter-current Shell & Tube Heat Exchanger (Figure-1) that fulfils the
specifications in Section 3 (Process Data) and includes the following items:
Item 1: Do energy balance and find heat duty (Q) and water flow rate
Item2: First start trial with 1-1 pass counter current exchanger and do LMTD
calculation and find out area, assuming overall heat transfer coefficient
based on outside area, Udo
Item 3: Select tube BWG (i.d, o.d and length) from available market and number of
tubes required and linear velocity of water (a velocity above 1 m/s should be
maintained).Do selection of tube side and shell side fluid with proper
justification
Item 4: Start second trial with suitable tentative selection of tube passes (say 1-4
pass) and repeat calculation and find out tube specifications and number of
tubes (You may use Tube-sheet layout and tube count of a shell and tube
heat exchanger Table which are available in standard data book)
Item-5: Select 25% cut segmental baffles with 0.15 m (6 inch) baffle spacing and
shell specification
Item 6: Estimate the tube-side and shell-side heat transfer coefficient (hi) using any
suitable correlation. Number of correlations are available such as Dittus-
Boelter equation, Colburn jH factor etc. At this stage there are number of
decision options on baffle spacing, number of tube passes etc are available to
get reasonably high local heat transfer coefficients.
Item 7: Calculate the ‘clean’ Overall coefficient, U on the outside tube area basis.
and repeat the above calculation to get area required, tube specifications,
number of required tubes. Neglect dirt factor calculation for U.
Item-8: No need to do pressure-drop calculation exercise but you may discuss this
variable and its role on design calculation.
N.B. You may be referred for various data from standard data book or from
Chemical Eng handbook- by Perry if required
2
go through S&T H.E. design calculation from Process Heat Transfer book by D.
Q. Kern. My expectations are your approaches and method of calculations
2. Project Report
This is an individual self-study mini-project on Shell & Tube Heat Exchanger
equipment design. Individual student is to require a report writing covering all
sections of design items. The report should also include an executive summary, along
with brief conclusions and recommendations. Your approaches and method of
calculations are also important and carry significant weightage
3. Process Data
The allowable pressure drop is 0.15 kg/cm2 on both tube and shell sides.
Ethylbenzene at the mean liquid temperature (87.50C):
Density: 840 kg/m3
Specific heat: 2.093 kJ/kg.K
Viscosity: 0.33 cp =3.3 x 10-4 kg/m-s
Thermal conductivity: 0.1156 W/m K = 0.0994 kcal/h m K
Water at 350C (mean temperature)
Density: 993 kg/m3
Viscosity: 8 x 10-4 kg/m s
Specific heat: 4.175 kJ/kg K = 1.0 kcal/kg K
Thermal conductivity: 0.623 W/m.K = 0.536 kacl/h m2K
.

Explain the meaning of the pour point, flash point for crude oil

Explain in details why crude oil requires to be refined and explain how this process is done with suitable diagram.

i) Determine the sedimentation coefficient of sphere particles with 0.1 micrometer size and density of 1200 kg/m^3 in tetrahydrofuran (THF) at 25 degrees celcius which density of THF is 889 kg/m^3 and its viscosity is 0.456 mPa.s. ii) Assume the particle size is doubled, determine the sedimentation coefficient.

One of the primary functions of impact testing is to determine whether a material experiences a ductile-to-brittle transition. Clearly explain what it means when a material exhibits “ductile-to-brittle transition” behavior?

The air exiting a furniture manufacturing factory from a extractor fan needs to be treated. What method could be used to
treat the organic gases in the air? Explain with the used of diagrams, how this would be done.

1. A distillation column is separating 100 kmol/h of saturated vapor feed that is 30 mol% ethanol, 25 mol% i-propanol, 35 mol% n-propanol, and 10 mol% n-butanol at a pressure of 1.0 atm.  We want a 98.6% recovery of i-propanol in the distillate and 99.2% recovery of n-propanol in the bottoms.  The column has a total condenser and a partial reboiler. The distillate flow rate in kmol/hr is ___________, the bottoms flow rate in kmol/hr is ____________, the molar fraction of i-propanol in the distillate is ______________, and the molar fraction of n-propanol in the bottoms is _________________.

Can the Rachford-Rice equation be used for binary systems? If yes, use it to solve the following:

A mixture of 50 mole % normal heptane and 50% normal octane at 30 degrees C is continuously flash distilled at 1 standard

atmosphere so that 60 mol% of the feed is vaporized. What will be the composition of the vapor and liquid products? Assume

constant relative volatility, αAB=2.0.

The composition of the vapor product is nearly_______________

A student is studying a temperature-composition diagram of a binary mixture of two pure substances, Kimium and Kallosium, at 1 atm. The molar mass of Kimium and Kallosium are 80 kg/kmol and 100 kg/kmol respectively. The substances are completely miscible, without any azeotrope at 1 atm. The student has obtained the following data from the diagram.

a) in an experiment, 1 kmol of liquid mixture of 30 mol% Kimium and remaining Kallosium is brought to an equilibrium temperature of 100 degrees Celsius at 1 atm.

i) how many phases are present?

ii) Find the amount of each phase in kmol.

iii) find the amount of each phase in kg.

b) How many phases will be present at equilibrium in a closed container filled with 25 mol Kimium and 75 mol Kallosium at 110 degree Celsius and at 1 atm?

1. Is there a relationship between the temperature and the dissolved oxygen concentration? If so, describe
their relation.

2. What is the importance of knowing the amount of dissolved oxygen in water quality?

3. What is the standard acceptable range of dissolved oxygen (DO) set by the government agencies for
water quality?

Write an introduction about heat exchangers and heat exchanger type (single shell pass, four tube pass shell and tube heat exchanger). Provide necessary references and citations (Harvard system).

Discuss the results that you would obtain and give reasons for the different values of the overall heat transfer coefficient and the heat transfer area, if you had to calculate the heat transfer area with and without the fouling factor. Also, include the effects of incorporating fouling factors on the final heat exchanger size and operation. Provide proper Harvard referencing with citations.