please show full explination and steps for answer A coal-fired power plant burns
ID: 1068492 • Letter: P
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please show full explination and steps for answer
A coal-fired power plant burns bituminous coal at a rate of 50.0 kg/s. Composition analysis shows that the coal contains 2.0 wt% of sulphur. Assume that the combustion efficiency of sulfur in the coal is 95% (i.e., 95% of the sulfur will convert to SO_2(g), and 5% of the sulfur will be present in the ash). What is the daily rate of emission of SO_2(g) without the installation of any flue gas desulfurization (FGD) system? Give your answer in kg/d. A FGD system is installed to remove SO_2(g) by the reaction: SO_2(g) + CaCO_3(s) + 2H_2O + 0.5O_2(g) = CO_2(g) + CaSO_4 middot 2H_2O_(s) What mass of the product CaSO_4 middot 2H_2O_(s) will be produced in one day? Assume a 100% yield of the above reaction (i.e., all SO_20(g) can be converted to CaSO_4 moiddot 2H_2O). Give your answers in kg/d.Explanation / Answer
a. The flowrate of coal is 50 kg/s which contains 2 % sulfur.
Therefore sulfur content in the coal is 0.02 * 50 = 1 kg/s.
Now combustion efficiency is 95 % for Sulfur. Therefore out of 1 kg/s, 0.95 kg /s will be converted to SO2.
0.95 kg/s of sulfur needs to be converted to moles = 0.95/32 kmoles of sulfur /s.
Now it can be observed that 1 mole of sulfur will give 1 mole of SO2. Therefore 0.95 / 32 kmoles of SO2 will be produced per second.
THerefore mass of SO2 produced will be (0.95/32) * 64 = 1.9 kg sulfur dioxide / s.
Now in 1 second 1.9 kg is produced, therefore in one day amount of SO2 produced will be 1.9 * 60 * 60 * 24 = 164160 kg per day.
b. For this question, since it is asked in kg/d, lets keep the basis as 1 day and not 1 second.
We have 164160 kg/day of SO2. = 164160 / 64 kmol/d = 2565 kmol/d of SO2. Yield is 100 %.
According to reaction stoichiometry of the FGD system, 1 mole SO2 will produce 1 moles CaSO4.2H2O.
Therefore moles of CaSO4.2H2O produced per day are 2565 kmol/d. Moar mass of CaSO4.2H2O = 172.14 kg/kmol.
Therefore mass of CaSO4.2H2O produced = 2565 * 172.14 = 441539.1 kg/d
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