. One wishes to burn 100 moles of a fuel mixture with weight percentages of 80% CH4, 15% C2H6, and 5% C3H8. Find the following: a) The molar composition of this fuel b) The three balanced reactions for the complete combustion of these hydrocarbons c) The stoichiometric amount of O2 needed for the complete combustion of the fuel d) The actual amount of air needed if you wanted 20% excess Knowing the molecular weights are 16 g/mol for CH4, 30 g/mol for C2H6, and 44 g/mol for C3H8.

A closed system contains an equimolar mixture of n-pentane and isopentane. a) Suppose the system is initially all liquid at 120°C and a high pressure, and the pressure is gradually reduced at a constant temperature. Estimate the pressures at which the first bubble of vapor forms and at which the last drop of liquid evaporates. Also calculate the liquid and vapor compositions (mole fractions) at those two conditions. b) Now suppose the system starts as a vapor at 1960 mm Hg and a high temperature, and the temperature is gradually reduced at constant pressure. Estimate the temperatures at which the first drop of liquid forms and at which the last bubble of vapor condenses. Also calculate the liquid and vapor compositions (mole fractions) at those two conditions. (use excel to solve question b.)

Describe 2 examples of how thermoplastic extrusions are rapidly cooled.

Methanol is produced by reacting carbon monoxide and hydrogen. A fresh feed stream containing CO and H2 joins a recycle stream and the combined stream is fed to a reactor. The reactor outlet stream flows at a rate of 350 mole/min and contains 10.6 wt% H2 , 64 wt% CO and 25.4 wt% CH3OH. This stream enters a cooler in which most of the methanol is condensed. The liquid methanol condensate is withdrawn as a product, and the gas stream leaving the condenser – which contains CO, H2 and 0.4 mole % uncondensed CH3OH vapor – is the recycle stream that combines with the fresh feed. Determine:

a) the molar flow rates of CO and H2 in the fresh feed

b) the production rate of liquid methanol (mol/min) and

c) the molar flow rate of the recycle stream.

(Draw and completely label the process flow diagram and determine all molar flow rate)

A copper ball of temperature 100 °C is immersed to a water bath of 50 °C. After 10 minutes the temperature of the ball is 80 °C and the temperature of the water is 60 °C. You may assume that Newton’s Law of Cooling is obeyed and all the heat lost by the ball is absorbed by the water. Find the equilibrium temperature of the ball as a function of time.

The feed to Column C1 is given in Figure 1. The separation is performed to produce a distillate of 95 mol% pure isobutane with a recovery in the distillate of 96%. Because of the sharp separation in Column C1 between isobutane and normal butane, asuume all propane goes to the distillate and all pentanes go to the bottoms. ( Propane = 2.2 lbmol/h, Isobutane = 171.1 lbmol/h, Normal butane = 226.6 lbmol/h, Isopentane = 28.1 lbmol/h, Normal pentane = 17.5 lbmol/h ). a) Compute the flow rates in lbmol/h of each component in each of the two product leaving Column 1. b) What is the percent purity of the normal butane bottoms product ? c) If distillate contained no normal butane, what would be the purity of normal butane at the bottoms ?

Methanol is produced by reacting carbon monoxide and hydrogen. A fresh feed stream containing CO and H2 joins a recycle stream and the combined stream is fed to a reactor. The reactor outlet stream flows at a rate of 350 mole/min and contains 10.6 wt% H2, 64 wt% CO and 25.4 wt% CH3OH. This stream enters a cooler in which most of the methanol is condensed. The liquid methanol condensate is withdrawn as a product, and the gas stream leaving the condenser – which contains CO, H2 and 0.4 mole % uncondensed CH3OH vapor – is the recycle stream that combines with the fresh feed. Determine a) the molar flow rates of CO and H2 in the fresh feed b) the production rate of liquid methanol (mol/min) and c) the molar flow rate of the recycle stream.

Five hundred twenty kilograms of aqueous solution containing 185 kg of dissolved MgSO4 is fed to a crystallizer wherein 80% of the dissolved salt crystallizes out as MgSO4·6H2O. The solubility of MgSO4 in the solution leaving the crystallizer is 20 g MgSO4 per 100 g H2O.

A. How many kilograms of the hexahydrate salt crystals are obtained from the crystallizer?

B. How many kilograms of water is evaporated in the process?

Sodium salicylate (HOC6H4COONa) is used in medicine as pain killer. It can be prepared from sodium phenolate (C6H5ONa) and carbon dioxide. Most commonly, solutions of sodium phenolate are produced by treating phenol with sodium hydroxide. Suppose phenol is run into a 30% excess hot aqueous caustic soda (87% NaOH by mass) with 130 m3 dry carbon dioxide at 300 kPa and 100oC per hr. After the desired amount of carbon dioxide is absorbed and reacted, sodium salicylate solution is withdrawn. The solution has a composition of 68.21% HOC6H4COONa, 8.73% C6H5ONa, 5.24% C6H5OH, 8.92% NaOH, and 8.90% H2O. The gaseous stream contains CO2 and H2O. On a basis of 100 kg hot aqueous caustic soda, calculate:

a) kg of salicylate solution/hr

b) degree of completion of the reaction

c) composition of gaseous stream

A mixture of saturated hydrocarbon and N2 us burned in excess air supplied at 25°C, 740 torrs with 90% RH. An orsat analysis of the stack gas shows 7.6% CO2, 2.28% CO, 1.14% H2, 6.03% O2 and 82.95% N2. With a dew point of 53.46°C. The stack gases leave at 300°C, 765 mmHg with a volume ratio of 2.049 m3 wet stack gas/m3 wet air.

a. The formula of hydrocarbon is?

b. Mole % analysis of the fuel

c. % excess air

1. Explain the mechanisms of transport in membranes. Support your explanation with appropriate figures.

2. Explain equations that describe pore resistance (of porous membranes) to bulk flow.

3. Explain equations that describe gas diffusion through porous membranes.

A clarified broth from the fermentation of sucrose using Aspergillus niger consists of 16.94% wt citric acid, 82.69% wt water, and 0.37% wt other solutes. To recover citric acid, the broth would normally be treated first with calcium hydroxide to neutralize the acid and precipitate it as calcium citrate, and then with sulfuric acid to convert calcium citrate back to citric acid. To avoid the need for calcium hydroxide and sulfuric acid, U.S. Patent 4, 25, 671 describes a solvent-extraction process using, which is insoluble in water and has a density of 0.847 g/cm^3. In a typical experiment at 30 C, 50 g of 20% wt citric acid and water was contacted with 0.86 g of amide. The resulting organic phase assumed to be in equilibrium with the aqueous phase, contained 6.39% wt citric acid and 2.97% wt water.

Determine (a) the partition (distribution) coefficients for citric acid and water, and (b) the solvent flow rate in, needed to extract 98% of the citric acid in 1300 kg/ h of broth using 5 countercurrent, equilibrium stages, with the partition coefficients from part (a), but ignoring the solubility of water in the organic phase. In addition, (c) propose a series of subsequent stages to produce near-pure citric acid crystals. In part (b), how serious would it be to ignore the solubility of water in the organic phase? 5.10. Extraction

An ideal vapour refrigeration cycle uses RF-134a as the working fluid and consists of the following steps:

(i)        Saturated vapour at 20 psia is compressed adiabatically and reversibly to a pressure of 120 psia. [The compressor]

(ii)       The vapour is cooled and condensed at constant pressure, leaving the condenser as a saturated liquid. [The condenser]

(iii)      The saturated liquid is expanded through a throttling valve to a pressure of 20 psia. [The throttling valve]

(iv)      The liquid-vapour mixture leaving the throttling valve is heated at constant pressure until it is 100% saturated vapour. [The evaporator]

The flow rate of refrigerant in this cycle is 0.1 kg s^-1.   For this cycle do the following:

(a)        Plot the cycle on the attached P-h chart for RF-134a.                                  

(b)       Calculate the power input to the compressor in kW.                                     

(c)        Calculate the heat transferred to the environment in the condenser in kW.  

(d)       Calculate the coefficient of performance (as a refrigerator) for the cycle.     (5marks)

Total = 20 marks

Note: Use the attached P-H chart for R-134a as your data source.

            1 kg = 2.21 lbm

            1 J = 9.48*10^-4 Btu

            1 bar = 10⁵ Pa = 14.5 psia