Topic - Chemical engineering ( reactor design ) polymath expert
For all problems, make sure to show ALL work, state ALL assumptions, include ALL reference points, and CIRCLE any answers requested (or the final if only one answer is requested).
You have a reactor that can hold 50 dm3 of gas that can be run co-currently or counter-currently. You are interested in running the following elementary reactions, which are in the gas phase:
A + B ←→ C + D
A + D → E
The reactants enter the reactor at 450K, while the coolant enters the reactor at 300K. The pressure of the reactor is 10 atm, The initial flow of A is 5.0 mol/sec, which is contained in a stoichiometric amounts with B. The first reaction has a reaction rate constant of 9.7 dm3/mol*sec at 440K and an activation energy of 31.4 kJ/mol. The second reaction has a reaction rate constant of 10.5 dm3/mol*sec at 400K and an activation energy of 45 kJ/mol. The equilibrium constant is 95 at 300K. The heat of reaction for reaction one is -20 kJ/mol, while the heat of reaction for reaction two is -27.5 kJ/mol. The heat capacity values are 40 J/mol for A, 25 J/mol for B, 15 J/mol for C, 30 J/mol for D, and 20 J/mol for E. The coolant can flow at a rate of 50 mol/sec, with a heat capacity of 17 J/mol. The heat transfer rate is 30 J/dm3*sec*K.
a) What conversion do you get for the co-current heat exchanger? For the counter-current heat exchanger? Are these values acceptable, based on what you know thermodynamically?
b) Using a co-current heat exchanger, what is the yield of C, which is the desired component? What is the selectivity of C/E? How do these values compare with the counter-current heat exchanger?
c) With the co-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream?
d) With the counter-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream entering the reactor?
You know that with a gas reactor, especially with a change in temperature, that a pressure drop could occur. Based on your calculations, you have determined that an appropriate α value is 0.02.
e) What conversion do you get for the co-current heat exchanger? For the counter-current heat exchanger? Are these values acceptable, based on what you know thermodynamically?
f) Using a co-current heat exchanger, what is the yield of C, which is the desired component? What is the selectivity of C/E? How do these values compare with the counter-current heat exchanger?
g) With the co-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream?
h) With the counter-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream entering the reactor?
You also know that if you want to drive your reaction forward, that you can use a membrane reactor. It just so happens that this reactor can also be modified for a membrane that would allow D to diffuse through, at a rate of 1.5/sec. To use a membrane reactor, though, you realize that with the D diffusing through, the reactor temperature will change, with the amount of D diffusing through the membrane times its enthalpy subtracted from the heat needed. The enthalpy of formation for component D is -15 kJ/mol, which is added to the heat capacity of D times the change in temperature from a reference point, which is 273K for the heat capacity given above. You also know that the equilibrium conversion is no longer useful at this point.
i) What conversion do you get for the co-current heat exchanger? For the counter-current heat exchanger?
j) Using a co-current heat exchanger, what is the yield of C, which is the desired component? What is the selectivity of C/E? How do these values compare with the counter-current heat exchanger?
k) With the co-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream?
l) With the counter-current heat exchanger, what temperature do you get for the stream exiting the reactor? For the coolant stream entering the reactor?
Write a paragraph, suitable for a high level manager, on the best way to operate the reactor, making sure to cover the best coolant flow direction, pressure drop usage, and membrane usage. This includes convincing the manager that this method is best by comparing conversion, yield, and selectivity.You may also want to include a comparison between product flows and maximum temperatures. Lastly, what change would you make to the reactor to improve the creation of the desired component (C), while reducing the creation of the undesired component - demonstrate this with a final set of values for this change.