Chapter 20, Air Pollution Control Video Solutions, Environmental Engineering

Problem 1

Taking into account cost, ease of operation, and ultimate disposal of residuals, what type of control device would you suggest for the following emissions?
a. Dust particles with diameters between 5 and $10 \mu \mathrm{~m}$.
b. Gas containing $20 \% \mathrm{SO}_2$ and $80 \% \mathrm{~N}_2$.
c. Gas containing $90 \% \mathrm{HC}$ and $10 \% \mathrm{O}_2$.

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02:28

Problem 2

An industrial emission has the following characteristics: $80 \% \mathrm{~N}_2, 15 \% \mathrm{O}_2$, $5 \% \mathrm{CO}$. What type of air pollution control equipment would you recommend?

Kratika Bhadauria

Numerade Educator

Problem 3

A whiskey distillery has hired you as a consultant to design air pollution control equipment for a new facility, to be built upwind from a residential area. What problems would you encounter and what would be your control strategy?

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Problem 4

Dust has specific gravity of 1.2 and particle size analysis as follows:
$$
\begin{array}{cc}
\text { Mean diameter }(\mu \mathrm{m}) & \text { \% of particles by weight } \\
\hline 0.05 & 10 \\
0.1 & 20 \\
0.5 & 25 \\
1.0 & 35 \\
5.0 & 10
\end{array}
$$
The dust is trapped by a cyclone with diameter 0.51 m , inlet width of 15 cm , and an inlet length of 25 cm , operating at five effective turns and $2.0 \mathrm{~m}^3 / \mathrm{s}$ air flow.
a. What is the removal efficiency?
b. What is the pressure drop at air temperature of $20^{\circ} \mathrm{C}$ and 1 atm ?
c. What is the separation factor? Is this a high-efficiency cyclone?

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06:02

Problem 5

A plate-type electrostatic precipitator is to remove particles having a diameter of $0.5 \mu \mathrm{~m}$ at a flow rate of $2.0 \mathrm{~m}^3 / \mathrm{s}$. The 40 plates are 5 cm apart and 3 m high. Ideally, how deep must the plates be to achieve removal?

Keshav Singh

Numerade Educator

Problem 6

Dust has particles with a drift velocity of $0.15 \mathrm{~m} / \mathrm{s}$. For a total air flow of $60 \mathrm{~m}^3 / \mathrm{s}$, what must be the number of $10 \times 10 \mathrm{~m}^2$ collecting plates needed to achieve $90 \%$ removal?

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Problem 7

Calculate the removal efficiencies for the dust described in Problem 20.4 for a standard cyclone, an electrostatic precipitator, and a fabric filter, using the curves of Fig. 20-12.

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02:12

Problem 8

Determine the efficiency of a cyclone of diameter 0.5 m , at a flow rate of $0.4 \mathrm{~m}^3 / \mathrm{s}$, and a gas temperature of $25^{\circ} \mathrm{C}$. The inlet width is $0.13 \mathrm{~m}^2$ and the area of the entrance is $0.04 \mathrm{~m}^2$. The particles have a diameter of $10 \mu \mathrm{~m}$ and a density of $2 \mathrm{~g} / \mathrm{cm}^3$.

Dading Chen

Numerade Educator

02:32

Problem 9

An electrostatic precipitator has the following specifications: height $=7.5 \mathrm{~m}$, length $=5 \mathrm{~m}$, number of passages $=3$, plate spacing $=0.3 \mathrm{~m}$. The flow rate is $18 \mathrm{~m}^3 / \mathrm{s}$ and the particle size is $0.35 \mu \mathrm{~m}$, and the particles have a drift velocity of $0.162 \mathrm{~m} / \mathrm{s}$. Calculate the expected efficiency.

Hubert Agamasu

Numerade Educator

Problem 10

For Problem 20.9 above, what would be the increase in efficiency achieved by doubling the length? by doubling the number of plates and reducing the flow rate to $9 \mathrm{~m}^3 / \mathrm{s}$ ?

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01:37

Problem 11

A copper smelter produces 500 tons of copper per day from ore that is essentially $\mathrm{CuS}_2$. The sulfur dioxide produced in this process is trapped in a sulfuric acid plant that produces $98 \%$ by weight sulfuric acid, which has a specific gravity of 2.3. If $75 \%$ of the $\mathrm{SO}_2$ produced is trapped by the acid plant, how many liters of $98 \%$ $\mathrm{H}_2 \mathrm{SO}_4$ are produced each day?

Harshit Mawandia

Numerade Educator

04:03

Problem 12

There are 168 h in a week, so that one 24-h day is $14.3 \%$ of a week. Therefore, you could decrease your personal electricity consumption by $14.3 \%$ by doing without electricity for one 24 -h period each week. Try this for a week. What activities did you have to curtail or change? You can do this in three 8-h periods or six 4-h periods, but they should be spread out during the day to encompass heavy-use hours as well as light-use hours (do not just take three 8 -h periods when you are asleep). If a fossil fuel power plant is $42 \%$ thermally efficient (that is, $42 \%$ of the heat generated is converted to electricity), what is your personal percent decrease in $\mathrm{CO}_2$ emission?

Khoobchandra Agrawal

Numerade Educator