Type
Quiz
Book Title
Chemical Process Safety: Fundamentals with Applications-- 4/e 4th Edition
ISBN 13
978-0134857770

978-0134857770 Chapter 6

December 2, 2020
Chapter 6
6-1. The flash point of the mixture occurs when the partial pressure of methanol is equal to the
vapor pressure of pure methanol at the flash point temperature.
From Appendix B, the flash point temperature for methanol is 11oC = 284.5 K
At the flash point temperature of 284.5 K
The partial pressure is given by
i i i
p x P
6-2. First compute the mole fraction on a combustible basis only, ignoring the non-combustible
air. We can obtain the flammable limits from Appendix B. So we have:
Then we use Equations 6-2 and 6-3 to compute the LFL and UFL of the mixture.
6-3. For carbon monoxide, the stoichiometric combustion equation is:
From Equations 6-10 and 6-11:
Clearly the UFL is in error – it cannot be greater than 100%. This compares to the LFL of
12.5% and UFL of 75.0% from Appendix B. The prediction is not very good.
For heptane the balanced combustion equation is:
From Equations 6-10 and 6-11:
This compares to the values in Appendix B of 1.0% to 7.0%. Much better than for CO.
6-4. From Appendix B,
Applying LeChatelier’s equation, Equations 6-2 and 6-3:
6-5. Ethylene: C2H4
Substituting into Equations 6-10 and 6-11
Actual values for ethylene from Appendix B are 2.7% and 36.0%. The estimation
equations do not work all that well in this case.
6-6. Refer to Example 6-6 in the text. Ethylene: C2H4
6-7. For carbon monoxide, the stoichiometric combustion equation is:
4
6-8. Need data for methyl alcohol.
The stoichiometric line is plotted from the 60% oxygen on the oxygen axis to the 100%
inert vertex.
6
6-9. Propane: C3H8
20 lbm propane = 9.07 kg of propane
From Appendix B, the energy of explosion for propane is given by the lower heating value,
or 2043.1 kJ/mole.
The molecular weight for propane is 3x12 + 8x1 = 44 gm/mole = 0.044 kg/mol
The number of moles of propane is 9.07 kg/0.044 kg/mol = 206 mol
From Equation 6-30:
6-10. Methane (CH4) VCE. House destroyed 100 feet from blast. 100 ft = 30.5 m
Molecular weight of methane is 16 gm/mole
From Equation 6-27,
Substituting,
7
0.02
6-11. Tank Truck Compartment: 11,860 Liters
T = 25oC, P = 1 atm.
a. Stoichiometric concentration of octane: C8H18.
2. Basic stoichiometry:
Assume 100 moles of air
b. Use Equation 6-30 in the text to determine the equivalent mass of TNT:
8
6-12. Worst case stability conditions: F-stability, 2 m/s wind speed, rural conditions
Apply Equation 5-17:
Solve for
m
Q
:
Need to determine concentration in kg/m3:
Convert to PPM:
Then use Equation 2-7 to convert to kg/m3:
6-13. a. T = 25oC = 298 K
b. Use Equation 6-30:
Use the ideal gas law to determine the total number of moles in the storage vessel:
Substituting into Equation 6-30:
TNT
c. Use Equation 6-27:
6-14. First, determine mass of TNT that will result in a 3 psi overpressure. Use Equation 6-28
to determine the scaled overpressure:
10
TNT
Now use Equation 6-30 to determine the mass of butane. Since this is a vapor cloud
6-15. Equation 6-22 applied: 1/3
G
MAX
dP
V K
dt
 
 
 
See drawings below:
12
6-16.
Procedure:
1. Use Antoine equation (Appendix C) to determine the saturation vapor pressure.
a. Acetone
b. Benzene
c. Cyclohexane
d. Ethyl alcohol
13
e. Heptane
f. Hexane
g. Pentane
sat
h. Toluene
6-17. The reaction is: 2KNO3 + 3C + S K2S + 3CO2 + N2
The required information is shown in the table below:
Species
f
H
(kJ/mol) Molecular Weight
14
This is for the reaction as written.
Thus, per kg of gunpowder: