Chemical Engineering Answers

A shell-and-tube heat exchanger has one pass on the shell side and two passes on the tube side (i.e.al-2shell and tube heat exchanger). It is being used for oil cooling. The oil flows in the tube side. It enters at 1120C and leaves at 78 0C The shell-and-tube fluid is water at a flow rate of1.35 kg/s, entering at 360C and leaving at 78 0C. The heat capacity of water is 4180j/(kg. K), and the overall heat transfer coefficient for the heat exchanger is 350 W/(m2.K). The geometry factor, F is 1.15. Determine the heat transfer area required for the unit.

A pipe of 6.5 cm outside diameter is covered with 5 cm (thickness) of asbestos layer

(conductivity = 0.12) and 4 cm (thickness) layer of cork (conductivity = 0.03). If the

temperature of outer surface of the pipe is 150 0 C and the temperature of the outer surface of

the cork is 35 0 C. Calculate the heat loss in W/m 0 C.

When doing a PLC project, there are 5 steps that are typically followed. Please list and describe these steps in your own words.

Using the PLC comparison table compare PLC’s from 2 different manufactures in term of support for IEC- 61131, communication protocols and redundancy. Try to explain what the advantage and disadvantage of the support would mean to you as an end consumer

A reaction between methanol and oxygen can be used to produce formaldehyde: 2𝐶𝐻3𝑂𝐻 + 𝑂2 (𝑔) → 2𝐻𝐶𝐻𝑂(𝑔) + 2𝐻2𝑂(𝑙): ∆𝐻̂𝑟 𝑜 = −326.2 𝑘𝐽/𝑚𝑜𝑙 The standard heat of combustion of hydrogen is: 𝐻2 (𝑔) + 1 2 𝑂2 (𝑔) → 𝐻2𝑂(𝑙): ∆𝐻̂𝑟 𝑜 = −285.8 𝑘𝐽/𝑚𝑜𝑙 (a) Use these heats of reaction and Hess’s law to determine the standard heat of the direct decomposition of methanol to form formaldehyde: 𝐶𝐻3𝑂𝐻(𝑙) → 𝐻𝐶𝐻𝑂(𝑔) + 𝐻2(𝑔)

An irreversible first-order homogeneous reaction A ----> P is carried out in a batch reactor. It is

required to produce 500 tons of product in 5000 hours of operation. The following data is

available.

Kat 1630C = 0.8 h-1 ; E = 28.96 kcal/gmol ; ΔHr = -15 kcal/gmol ; CPA= 150 kcal /gmol K

A=    kg / m3

;

The times necessary to fill and drain the reactor are 10 & 15 minutes. Negligible reaction occurs

in 10 minutes required to heat reactor to 1630C. XA= 90% . Compare the size requirements for

adiabatic and isothermal operation.

A barite composed of 100% BaSO4 is fused with carbon in the form of coke containing 6% ash (which is infusible). The composition of the fusion mass is

BaSO4 11.1%

BaS 72.8

C 13.9

Ash 2.2

_____

100%

Reaction:

BaSO4 + 4C → BaS + 4CO

Find the excess reactant, the percentage of the excess reactant, and the degree of completion of the reaction. 

One thousand kilograms per hour of a mixture of benzene (B) and toluene (T) that contains 60 % benzene by mass are separated by distillation into two fractions. The mass flow rate of benzene in the top stream is 470 kg B/h, and that of toluene in the bottom stream is 350 kg T/h. The operation is at steady state. a. Draw and label the flowchart of the process. b. Write balances on benzene and toluene to calculate the unknown component flow rates in the output streams.

Hydrogen can be produced using a process called coal gasification. It is desired to supply nearly pure oxygen to this process. Oxygen is separated from nitrogen out of the air (79 mol% nitrogen and 21 mol% oxygen) via a process known as cryogenic distillation. A cryogenic distillation unit has a feed of 2000 kgmol/hr air. The top stream has 1400 kgmol/hr nitrogen and the bottom stream has 320 kgmol/hr oxygen. a. Draw and label the flowchart of the process in block diagram. b. Write balances on the oxygen and nitrogen to determine the unknown component molar flow rates.

the distillation column of an Acetaldehyde plant has the following process

conditions temperature, 60 0C; gas density,3220 g/cm3., liquid density,

0.74g/cm3., L/D =3; Bottom flow rate = 139 kg/hr; distillate flow rate=25kg/hr;

Liquid flow rate at top of the column =75 kg/hr; vapour rate at the top =

100kg/hr: Plate spacing of60 cm; maximum vapour density = 1.603 m/s;

assuming safe operating velocity as 60% of this value, determine (a) the column

cross-sectional area (b) diameter of the column.