A cyclone cluster is required to classify a slurry feed of 29wt% solids (SG_p = 2.9) at a solids flowrate of 410 tonnes per hour.

a. Determine the diameter of the cyclones required to operate at a d₅₀ of 70 micrometres. The cyclones are to be operated at a pressure drop of 150 kPa. The SG of the liquid phase water = 1.0.

b. Determine the number of cyclones that are required if the capacity of the cyclone found in question (a) is 75 litres/second.

Using an iron-iron carbide (Fe-Fe3C) Phase Diagram, identify and discuss the different important phases found in this diagram and the development of microstructure in iron-carbon alloys.

Describe each type of phase diagram and show all phase regions with all the relevant information for each region.

(A) Binary isomorphous phase diagram

(B) Binary eutectic phase diagram

Have you ever wondered what happens to your recycled plastics when they are picked up at the curb by the trash truck? It gives everybody a good feeling to recycle, but what if recycling means more trash fees?

Michael Dumper, CEO of Belmont Waste Hauling, recently told citizens of Belmont at a recent Town Council meeting that because of the closure of the closest recycling center, he will now need to haul recycled plastics almost 200 miles to be recycled. Recyclables make up almost 40% of the trash load from Belmont and as a result Belmont Waste Hauling will lose money on hauling recyclables.

The city of Belmont requires all municipal buildings and all newly constructed public buildings to provide recycling containers for use. Belmont Waste Hauling will continue to haul the city’s waste and recycling this year, but the company’s contract with the city expires next June. At that point the city will need to renegotiate a new contract, maybe with a new company.

Many of the larger trash hauling giants are not willing to deal with the many issues involved with recycling plastics and simply bury it in landfills. It takes a lot of money up front to recycle, and they are not willing to lose any amount of profit on any load of trash.

Michael Dumper maintains that he wants to keep the Belmont trash contract. He hopes that with a small increase in fees he can continue to serve the city of Belmont. Competition forces companies to stop recycling programs unless consumers are willing to pay for them, he says. And yes, finding recycling centers that are still sorting and recycling is a challenge, but Michael is not yet conceding defeat and will continue to face the challenge of finding the plants that are still operating.

1. Discuss the reasons some trash haulers dump recyclable plastics into landfills.
2. Explain why aluminum cans are recycled more often than most other recyclables.
3. Give three reasons why it is important to recycle as much as possible.
4. Identify three materials that can be recycled, other than plastic or aluminum, and explain how they are recycled.

Consider an irreversible 2nd-order reaction (A + B → C) in a batch reactor with the initial molar ratio of ΘB=CB0/CA0. Find the relation between time (t) and conversion (XA). (Hint: You need to consider cases of both CA=CB and CA≠CB.)

In a process plant, a large amount of saturated steam is available at a pressure of 2 MPa. Connected to the saturated steam system through a valve is a turbine followed by a well insulated tank which is initially evacuated (P=0). The volume of the tank is 2000 L. When emergency power is needed, the valve is opened and steam flows through the turbine, generating power and the tank fills until its pressure is 2 MPa.

At the end of this process the temperature of steam in the tank is 250 °C.

a) Draw a diagram of the system showing all mass and energy flows

b) Making (and listing & justifying) suitable assumptions, determine the amount of work generated by the turbine.

c) Determine the entropy generated by this process.

d) If there was no pressure drop across the valve when it is fully opened, and the turbine is adiabatic and isentropic, what would be the final temperature in the tank?

Explain briefly the following terms: a) Superheated steam b) Saturated steam c) Dryness fraction d) Sensible Heat e) Latent Heat f) Dry steam g) Wet Steam.

2. A solution of 500 kg of Na2SO4 in 2500 kg water is cooled from 333 K to 283 K in an
agitated mild steel vessel of mass 750 kg. At 283 K, the solubility of the anhydrous salt
is 8.9 kg/100 kg water and the stable crystalline phase is Na2SO4.10H2O. At 291 K,
the heat of solution is −78.5 MJ/kmol and the specific heat capacities of the solution
and mild steel are 3.6 and 0.5 kJ/kg deg K respectively. If, during cooling, 2 per cent
of the water initially present is lost by evaporation, estimate the heat which must be
removed. (use both methods)

Task # 1.

For the homogeneous autocatalytic reaction A + B → 2B, where –rA = kCACB, aconversion rate of A of X = 0.44. The velocity constant is k = 10-3  m3 / (mol s). The feed stream of 0.1 m3 / s contains A with CA0  = 90 mol / m3 and B with CB0 = 10 mol / m3. It is considered whichreactor configuration that will be most suitable

1.1

The reaction must take place in a flow reactor. Set up the stoichiometric table and find CA and CB asfunction of CA0 and X.

A high grade semi-anthracite coal has a complete analysis of 85.86% C, 4.44% H, 2.7% O, 1.2% N, 5% ash and 0.8% S. Analysis of the Residue shows 58% C and 42% ash. Air is
supplied dry at 30°C and 750mmHg. Partial orsat analysis of the stack gas (400°C, 755mmHg) shows 8.05% CO2, 2.42% CO and 2.9%H2.Assume the S and N gasified burns to SO2 and NO respectively. Calculate
a. % excess O2
b. Complete orsat analysis of stack gas
c. m3 stack gas/ m3 air

A sample of hemispherical particles of quartz having the uniform particle diameten of 13.2 cm with a density of 0.89 g/cm3 and the total surface area is 3980.6 mm2/g. What is the total mass of the sample? Sphericity of sample can be calculated for a hemispherical particle with an individual particle diameter of 1.5 cm.

We can precipitate lead with many anions, including sulfide and sulfate (among others). Using the two equilibrium relationships below, the treatment target (based on the ‘action level’) of ~7x10-8 M, and the associated costs of the salts, which would you select (ignoring all other considerations, which are many, but looking at cost alone) to remove lead from 100 m3 of solution with lead at 2x10-5 M? In each case you will have to determine the amount of anion (sulfide or sulfate) needed to i) form the solid, and ii) increase its concentration in solution from the initial value of 0 to the equilibrium value from Ksp. Assume CaS costs ~$440/kg and CaSO4 costs ~$1/kg (MW of CaS = 72.2 g/mol, MW of CaSO4 = 136 g/mol).

Ksp = 1x10-28 = [Pb2+][S2-]

Ksp = 2.53x10-8 = [Pb2+][SO42-]

a. Using only P-v-T data, estimate the enthalpy of vaporization of water at T oC where, T is T= 38 and so on. b. If the enthalpy (h), as an unmeasured thermodynamic property is related to the temperature (T) and Pressure (P) as measured thermodynamic properties according to the following relation: h = f (T,P). Show that: dh = Cp dT +[ v – T (dv/dT)p] dP Where: Cp is the specific heat at constant pressure, v is the specific volume.

(a) In a dropping mercury electrode (dme), a new measurement is made on each drop. The drop size can be controlled by the diameter of the capillary which feeds the dme. Discuss advantages and disadvantages of using a small drop vs. a large drop.
(b) Discuss the differences between the hydrodynamic boundary layer and the diffusion boundary layer near the surface of a rotating disk electrode.
(c) Discuss advantages and disadvantages of linear vs. cyclic voltammetry.