Chemical Engineering Answers

Find the Laplace Transform of the following functions:

i)ft=e-tsinh 3t

                                                       ii)ft=t9e5t

Discuss the similarities between the Rockwell and Brinell tests principles for the determination of hardness of the material.

If the reaction in a process is incomplete, explain if it affects the standard heat of reaction.

A waste gas and theoretical air are entering a furnace at 25°C to produce flue gas at 150°C. If pure O2 rather than air is fed to the furnace, would the flue gas temperature be higher, lower or the same? Provide reasons for the answer.

A reaction A → Bis to be conducted in two CSTRS in series. The steady state conversion desired is Xf. The reaction rate as a function of conversion is given by r = -1/(1+X). If the feed contains no B, then the conversion in the first reactor that minimizes the total volume of the two reactors is

1-Xf

0.2Xf

0.5Xf

0.5(1-Xf

After recovering all available sugars from your waste stream, you used a chemostat culture of Corynebacterium glutamicum to convert 12 g L-1 glucose to L-lysine. The steady state process was performed

aerobically in a 50 m3 continuous stirred tank reactor (CSTR). The laboratory based performance data

indicated that the yield of biomass from substrate is Yxs is 0.1 g g-1. From your experience, you know

that you can maximise production in continuous reactor systems by maximising the dilution rate.

1. As you had sufficient performance data, you decide to go to your office to determine the lowest

mean residence time τ you can operate to maximise the growth of Corynebacterium glutamicum.

You further calculate the product yield and maximum product yield at this dilution rate on mass

basis. In your calculations you assumed steady state operation.

The working volume of the reactor is 50 m3. The gas flow rate into the reactor is 0.75 vvm (volume gas per volume liquid per minute). Using the instrumentation available to you, you can confirm an inlet and outlet O2 concentration in the gas phase of 40% and 16% by volume, respectively. For the purposes of your calculation, you reasonably assume the flow rate across the reactor is constant. You find that the residual dissolved oxygen concentration in your system is 2.5 mg L-1 and confirm that the saturation dissolved oxygen concentration achieved on sparging water with air at 30oC is 7.5 mg L-1.

1. Knowing that temperature influences the rate of gas-liquid mass transfer, you decide to calculate the saturation dissolved oxygen concentration at 30oC using the enriched gas stream containing 40% oxygen.

2. Using a mass balance across the reactor, you further calculate the Oxygen Utilisation Rate (OUR)