Chemical Engineering Answers

A ore with a work index of 12.5 kWhr/t is ground in a lab ball mill for 10 minutes using a
20,125 gram charge of half-inch stainless steel balls. The 80 % passing size of the ore was
initially 4 mm while the 80 % passing size after grinding was 93 microns. A second sample of
a similar ore was subjected to the identical procedure. The sample had an 80 % passing size of
3 mm and the product showed an 80 % passing size of 107 microns. What is the work index
of this second ore sample?

A piston-cylinder device contains 3.5 kg of water. Initially the water is a saturated
liquid at 105 °C (State 1). The water is heated until the piston just touches the stops, at
which point the volume is 2.18 m3 (State 2). Heating of the system continues until a
pressure of 1000 kPa is reached (State 3).
(a) Calculate the work done by the device during the process from state 1 to state 3
(kJ).
(b) Calculate the heat transfer required for this process (kJ).
(c) Draw the process on a pressure - volume diagram with respect to the saturation
lines.

A solution is to be concentrated from 10 to 50 percent solids in a single effect evaporator. Steam is available at a gauge pressure of 3 bar with reference to atmospheric pressure of 1 bar. A pressure of 0.5 bar absolute is maintained in the vapor space. The feed rate to the evaporator is 10,000 kg/hr at 30oC. The specific heat and latent heat of evaporation of feed solution are equivalent to that of water. The overall heat transfer coefficient is 1000 W/(m2-K). The solution has a negligible elevation in boiling point and heat of dilution. Calculate steam consumption and steam economy? -

Define Equilibrium

1.) Motor Benzole is a mixture of 3 lower aromatic hydrocarbons, benzene, toluene, and xylene in proportions of 75%, 15% and 10% by weight. Its calorific value is 41.9 MJ/kg. A motor is run using benzole and gives an exhaust gas which analyzes 10.7 % Carbon Dioxide 1.07% CO

Calculate:
a.) % excess O2
b.) Complete Analysis of the Exhaust gas
c.) % heat loss due to CO

Carbon dioxide and hydrogen gases are passed through a catalytic reactor and methyl alcohol is obtained according to the following reaction.

CO2 + 3H2 CH2OH + H2O Gas mixture enters the reactor at a stoichiometric rate and at 25 ° C.

There is 0.5% nitrogen gas in the feed stream. 57% conversion takes place in a single pass through the reactor. It is not required to have more than 2% nitrogen in the reactor. Methyl alcohol and water vapor in the gas mixture leaving the reactor are condensed in a separator and separated at 70 ° C. The remaining gases (CO2, H2 and N) are recycled. However, some of the gas mixture is thrown out for nitrogen cleaning.The temperature of the discharged gas mixture is 100 ° C and the returning gas mixture temperature is 90 ° C.

Accordingly, if 1 mol of methyl alcohol is produced,

Calculate the amount of insurgency

Note C = 91 J / mol. ° C for the liquid methyl alcohol.

The overhead condensate from a distillation column of density 0.6 g/cm3 and viscosity 0.6 x 10-4 Pas is fed at a rate of 300 kg/min from the condensate drum held at a gauge pressure of 12 bar to a pressurized storage vessel at a gauge pressure of 10.2 bar prior to further processing. The pipeline has a length of 2.5 km and an inside diameter of 7.5 cm with a wall roughness of 0.046 mm. If the difference in level of the condensate in the condensate drum and the discharge of the pipe into the storage vessel is 1 m, determine the power requirement of the pump and the motor assembly if their combined efficiency is 65%. Allow for entrance and exit losses and where the pipe contains fifty-six 90o elbows of 0.7 velocity heads each and four open gate valves of 0.15 velocity heads each

A shell and tube heat exchanger is designed to warm air from the environment by condensing steam that is passed through the tubes on the other side. The maximum air flow is 30 kg/min, and the air is inlet at the temperature and pressure of the environment 285K and 1 bar respectively. The steam flows through the system at a pressure of 10 bar and a flowrate of 3 kg/min. the quality of steam at the inlet is 0.9 and at the exit is 0.2. calculate the lost work during this process

Producer gas analyzing 25.3% CO, 13.2% H2, 0.4% CH4, 0.5%O2, 5.4% CO2, and 55.2% N2 is burned in excess air at 25°C, 745 torrs and 60% RH. Partial Orsat analysis of the stack gas shows 16.13% CO2, 1.79% CO and 0.72% H2. Calculate:

a. % Excess O2

b. Complete Orsat analysis of stack gas

c. GHV (kJ/mol)

d. % calorific value lost due to CO and H2