You have been sent by the Environmental Protection Agency to measure SO2 emissio

Question

You have been sent by the Environmental Protection Agency to measure SO2 emissions from a small industrial power plant. You withdraw and analyze a gas sample from the boiler stack and obtain the following composition: 75.66% N2, 10.24% CO2, 8.27% H2O, 5.75% O2, and 0.0825% SO2. You show these figures to the plant superintendent next day, and she insists they must be wrong, since the fuel was a natural gas containing methane and ethane, and no sulfur. You ask if they ever burn another fuel, and the superintendent replies that they sometimes use a fuel oil but the plant log shows that they were not doing so when the measurements were made. You do some calculations and prove that the oil and not the gas must have been the fuel; the superintendent checks further and discovers that the plant log is in error and you are right.

a. Calculate the mole ratio of carbon to hydrogen in the fuel, and use the result to prove that the fuel could not have been the natural gas.

b. Calculate the mass ratio of carbon to hydrogen and the wt% of sulfur in the fuel, assuming that C, H, and S are the only elements present. Then use the results in conjunction with the ultimate fuel oil analyses in Table 24-6 of Perry’s Chemical Engineers’ Handbook18 to deduce the most probable classification of the fuel oil.

Explanation / Answer

a.Given: N2=75.66%=0.7566 g N

CO2=10.24%=0.1024 g CO2

H2O=8.27%=0.0827 g H2O

O2=5.75%=0.0575 g O2

SO2=0.0825%=0.00825g SO2

Now, determine the element i.e C and H in grams

CO2=0.1024g*(12.011g/44.0098)

=0.0279 g

H20=0.0827g*(2.0158/18.0152)

=0.0092g

Convert gram into moles

C=0.0279/12.011=0.0023

H=0.0092/1.0079=0.0091

Now divide the molar amount C and H by the 0.0023 or the lowest value to convert them into whole numbers

C=0.0023/0.0023=1

H=0.0091/0.0023=3.9=4

b.. Mass ratio of carbon to hydrogen

CO2=8.27

H20=5.75

C=12/44*100=27% C in CO2

H=1/18*100=5.5% C in CO2

Now 27% of 8.27=2.23

5.5% of 5.75=0.31

Now mass ratio of C: H

=2.23/0.31

=7.19

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