Chemical Engineering Answers

A 30-plate bubble cap column is to be used to remove n-pentane

from oil by means of pure steam stripping. The inlet oil contains 6% n-pentane

by volume and it is desired to reduce the n-pentane to 0.1% by volume. Assume

isothermal operation and an overall plate efficiency of 30%. Find out the ratio

of actual to minimum steam consumption. The equilibrium relation for the

system is y=3x.

A can of pumpkin puree 8.73cm diameter by 11.43cm in height is being heated in a steam retort in which the steam pressure is 100 kPa above atmospheric pressure. The pumpkin has a thermal conductivity of 0.83Jm's "C", a specific heat of 3770Jkg and a density of 1090kgm³. The temperature in the can prior to retorting was 20°C. Plot out the temperature at the centre of the can as a function of time until this temperature reaches 115°C. Assume is very high

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. 

A tank of volume 0.00354 m³ contains 0.00292 kg of saturated water vapour at 0.143 MPa. A line is attached to the tank in which water vapour flows at 0.7 MPa and 200 °C. Steam from this line enters the tank until the pressure in the tank is 0.7 MPa.

                             i)     Why can this process be analysed as uniform flow?

[2 marks]

ii) State THREE assumptions, other than uniform flow, that must be made when analysing this process.

[3 marks]

ii)              Use the mass balance to write an expression for the final mass of steam, m₂, in the tank.

[2 marks]

iii)            Write an expression for the energy balance for the system based on the assumptions made in part (ii) and calculate the mass of steam that enters the tank. The properties of steam under these conditions are:

h_in = 2845.3 kJkg^-1 u₁ = 2517.6 kJkg^-1 and u₂ = 2749.9 kJkg^-

1

[5 marks] v) Predict and explain what would happen to the temperature of the steam in the tank during this process.

[3 marks] 

Variation of the rate constant with temperature for the reaction

2N2O5 2N2O4+O2

is given in the following table.

Determine graphically, the activation energy for the reaction and frequency factor. (BL-3)

What is the physical significance of NTU?

(1) Describe the composition of fabrication

(2) Describe the physical properties of fabrication

(3) Describe the mettods of fabrication

Describe the composition , physical properties and mettods of fabrication , and uses of acid resistant brick

A 10min experimental run shows that 75% of liquid reactants is converted to produce by a half other rate 1/2 other rate or half. What will be the amount converted in a half hour (1/2 hr run)mm

By what percentage would the rate of absorption be increased or decreased by increasing the total pressure from 100 to 200 KN/m2 in the following cases:

a. The absorption of ammonia from a mixture of ammonia and air containing 10% of ammonia by volume, using pure water as solvent. Assume that all the resistance to mass transfer lies within the gas phase.

b. The same conditions as (a) but the absorbing solution exerts a partial vapour pressure of ammonia of 5 KN/m2. The diffusivity can be assumed to be inversely proportional to the absolute pressure.