Page 334 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

10.10 Practice Problems 311

6. A selective catalytic reduction system is designed to remove 80 % of NO x in the
flue gas. Calculate the stoichiometric amount of ammonia needed if flue gas has
3
500 ppmv of NO x and is flowing at a rate of 10,000 m per minute at 300 °C
and 1 atm.
7. The flue gas from an industrial power plant contains 1100 ppmv of NO and is
3
emitted at a rate of 1200 m /s at temperature of 573 K and pressure of 1 atm. A
selective catalytic reduction system is designed to remove 75 % of NO. Cal-
culate the quantity of ammonia needed in kg/hr.
8. Particles with low conductivity passing through an ESP are likely to

a. form a dust cake that can be easily removed from the collecting plate
b. restrain the gas stream
c. lose ions quickly through the collection plate
d. have low migration speed because of the resistance from the dust cake on
the collection plate.
9. In a power plant, SCR is used for NO emission control by conversion of NO
into N 2 . Urea is preferred over ammonia because

a. urea has a great inertia and cover a wider range of flue gas
b. urea costs less and less evaporative
c. urea based SCR is not sensitive to dust
d. urea based SCR is not sensitive to temperature.
10 Which one of the following statements is most accurate?

a. High dust SCR is less frequently maintained than a low dust SCR
b. The gas temperature passing through a high dust SCR is lower than that of a
low dust SCR
c. The catalyst in a high dust SCR costs less than that in a low dust SCR
d. None of the above.

References and Further Readings

1. Agnihotri R, Chauk S, Jadhav R, Gupta H, Mahuli S, Fan L-S (1998) Multifunctional sorbents
for trace metal capture: fundamental sorption characteristics. In: Proceedings of the 15th
annual international Pittsburgh coal conference, Pittsburgh, PA, USA, Sept 1998
2. Bae SW, Roh SA, Kim SD (2006) NO removal by reducing agents and additives in the
selective non-catalytic reduction (SNCR) process. Chemosphere 65:170–175
3. Basfar AA, Fageeha OI, Kunnummal N, Al-Ghamdi S, Chmielewski AG, Licki J, Pawelec A,
Tyminski B, Zimek Z (2008) Electron beam flue gas treatment (EBFGT) technology for
simultaneous removal of SO 2 and NO x from combustion of liquid fuels. Fuel 87:1446–1452
4. Biswas P, Wu CY (1998) Control of toxic metal emissions from combustors using sorbents: a
review. J Air Waste Manag Assoc 48:113–127
5. Borman GL, Ragland KW (1998) Combustion engineering. McGraw-Hill, New York