978-1118741498 Chapter 11 Solution Manual Part 2

11.9 This problem allows you to think about how exposure impacts the concentration of

air pollutants you are exposed to. (a) Maintain a diary for one full day and record all the

locations you visit. Include the times of entry and exit for each location. Also record any

interesting air quality information for each location. Calculate the percentage of time

spent in each type of location. Summarize the data in a table. (b) In which location did

you spend the most amount of time? The least? (c) Calculate the 24–hr time integrated

average exposure concentration (units of µg/m3) to airborne particles based on your

recorded activity patterns, using the average airborne PM10 concentration for different

locations provided below.

Location

Average Airborne PM

10

Concentration (µg/m

3

)

Home

90

Office–Factory

40

Bar–Restaurant

200

Other Indoor

20

In a Vehicle

45

Outdoors

35

(a) (b) Students should be developing this type of table from the data entered into

their dairy for their 24 hour period. Their raw data from the diary can be attached

(d) Now add a 35 µg/m3 “proximity effect” to one of your locations above that we will

assume is from exposure to cigarette smoking at that location. How does this change

your 24-hr time integrated average exposure concentration (units of µg/m3) to airborne

particles?

Solution:

Students’ answers should vary.

11.10 (a) Define NAAQS and (b) identify the NAAQS pollutants.

Solution:

NAAQS is described in Section 11.4.

11.11 On January 12, 2013 the AQI in Beijing (China) the AQI was determined to be

775. In contrast, on January 11, 2013, Salt Lake City (Utah) has a reported AQI of 142

compared to a value of 67 in San Francisco’s and a value of 23 in Las Vegas. Develop a

table with three columns. List the four cities, the AQI reported above, and the third

column should provide the level of health concern related to an AQI for general and

sensitive populations.

Solution:

11.12 The following data on U.S. population, number of licenses drivers, and number of

vehicles was obtained from the U.S. Department of Transportation, Federal Highway

Administration (http://www.fhwa.dot.gov/policyinformation/statistics/2010/dv1c.cfm).

(a) Determine the rate of growth (on a per year basis) for the population, number of

licensed drivers, and number of vehicles. (b) Are the rates of growth similar or different?

Solution:

11.13 A travel demand management action is planned that will add parking spaces to an

existing park–and-ride facility that is served by transit. The plan will add 120 parking

spaces. Assume the new spaces will have a 95 percent estimated utilization rate and

these individuals will use the available light rail and bus service. Also assume that the

average commute that will be eliminated is 42 miles roundtrip (distance from lot to

destination and return), and there are 250 operating days per year. (a) What is the annual

reduction in vehicle miles traveled from implementation of the park and transit ride

facility? (b) if the emission factor for reactive hydrocarbons is 0.23 grams/mile driven

and for NOx is 0.40 grams per mile driven, what is the estimated reduction in air

emissions for both of these air pollutants over the year?

Solution:

11.14 True or False? Compared to a baghouse with a high pressure drop, a baghouse with

a low pressure drop would need a large fan and require more energy to move the gas

through the baghouse.

Solution:

11.15 A baghouse that employs a shaker collection method is being designed to remove

99.75 percent of an incoming stream of sawdust particles originating from a sawmill

plant. What fabric area is required for the baghouse if it treats 15,000 ft3/min of polluted

air? How many bags are required if the bags are cylindrical and are 6 inches in diameter

and 15 ft long? Assume the filter manufacturer has specified a woven fabric.

Solution:

11.16 You are assigned to determine the number of filter bags required for an 8-

compartment baghouse that uses pulse–jetting as the method to remove particulate matter

from the bags. The following information is known: process gas exhaust rate is 100,000

ft3/min and the recommended air–to–cloth ratio is 4 ft/min. The bags specified by the

manufacturer have a diameter of 6 inches and height of 10 ft. (a) what is the total required

fabric area? (ft2)? (b) What number of bags is required? (c) How many bags are in each

compartment?

Solution:

11.17 A thermal oxidizer incinerator operates as a plug flow reactor at a temperature of

250oC and has a gas residence time of 0.3 seconds (a) If the pollutant (vinyl chloride)

enters the incinerator at a flow rate of 3,000 m3/min and it is desired to remove 99.99% of

the pollutant, what should the length of the incinerator be? (b) What is the length of the

incinerator if the desired removal is increased to 99.99995? The first order rate constant

for vinyl chloride removal is 45/sec at 250oC and the inside diameter of the incinerator

(which is shaped like a cylinder) is 1 m.

Solution:

11.18 A tubular thermal oxidizer is operated at 225oC to remove toluene (C6H7) from a

polluted airstream. The residence time for the gas is 1 sec. (a) Write the balanced

reaction for theoretical oxidation of toluene to carbon dioxide and water. (b) If the

toluene enters the incinerator at a flow rate of 2,500 ft3/min and the reaction rate constant

is 7.2/sec at this temperature, what percentage of the toluene is removed? (c) What is the

length required for the oxidizer if the inside diameter is 4 feet?

Solution:

11.19 A biofilter design uses a media that consists of a mixture of wood chips and

compost at a ratio of 1 to 3 parts wood chips to municipal compost. The biofilter has the

following dimensions, L = 8 m, W = 4.8 m, Depth = 0.35 m, and the air flow rate is 2.6

m3/s. (a) What is the empty bed residence time (sec)? (b) Using the Table provided in the

chapter that relates empty bed residence time to application, what application(s) might

this biofilter be appropriate for?

Solution:

b. From table 11.23, agriculture is the application this biofilter may be used for.

11.20 Calculate the (a) stack emissions and (b) fugitive emissions if some process

equipment that is associated with a hood system generates 220 kg/hr of VOCs, the hood

capture efficiency is 87%, and the collection efficiency of the air pollution control

technology used to treat the captured air emissions is 95%.

Solution:

97.5% efficiency. The plant produces 350 metric tons of sulfuric acid at 100% purity

every day. A wet scrubbing system is installed to reduce the SO2 emissions and has a

removal efficiency of 97%. The emission factor for this process equals 17 kg SO2/metric

ton of raw material processed. (a) What are the daily emissions of SO2 from the

manufacturing facility prior to treatment? (b) What are the daily emissions of SO2 from

the manufacturing facility after treatment?

Solution:

11.22 Assume the emissions factor for release of mercury from a solid waste incinerator

is 0.107 lb per ton incinerated and for dioxin is 2.13×10-5 lb per ton solid waste

incinerated. Estimate the daily emission rates (lb pollutant/day) and annual emissions

rates (lb/yr) of each of these hazardous air pollutants. Assume the incinerator processes

2.88 ×106 lbs of solid waste per year.

Solution:

11.23 Acetone is released from combustion of 100,000 metric tons of wood waste per

year. The wood waste has an average heat content of 0.05 MM BTU/lb. The reported

emission factor for acetone emitted from a waste bark fired boiler with no emissions

control is 9.5×10-3 kg/metric ton of wood burned. What are the annual emissions of

acetone from this facility (metric tons per year)?

Solution:

11.24 A company annually applies 25,000 liters of a surface coating to their product. The

surface coating contains the VOC, acetone. The emissions are collected and an

emissions control technology is installed that reduces the VOC emissions by 80%. The

company is required to report their emissions to the atmosphere if they exceed 3,500

kg/year. For this coating process operation, there is no loss of the coating compound to

the coating equipment and no loss to the system’s liquid or solid waste streams. All the

VOC applied is captured by the collection system prior to treatment. The Material

Safety Data Sheet reports that the surface coating product contains 25% by weight

acetone and the specific gravity of the material is 1.35 kg/L. Use a mass balance

approach to estimate if the company must report their air emissions to the state regulatory

agency.

Solution:

11.25 A company applies 21,000 liters of a coating every year that contains three VOCs;

0.26 kg xylene per liter of coating, 0.040 kg n-butyl alcohol per liter of coating, and 0.13

kg ethyl benzene per liter of coating. (a) What is the total mass of VOC in the coating

(kg VOC/liter of coating)? (b) Estimate the total mass of VOCs released to the

atmosphere every year (kg/year) assuming no collection or treatment of the VOCs takes

place. (c) What is the total mass of VOCs released to the atmosphere assuming that 8%

of the applied VOC is retained in a liquid wastestream and is discharged to the

wastewater treatment plant and the company installs some control technology which

captures and degrades 60% of the collected air emissions?

Solution:

11.26 A company performs measurements that show the VOC xylene is present in the

stack gas and the gas flow rate is 2,200 m3/min. The concentration of xylene was

measured exiting the stack on a weekly basis and averaged 0.62 kg/hr. The

manufacturing process runs 6,700 hours every year. If the reporting threshold for the

xylene is 3,200 kg/year, use the source measurements to determine if the company

exceeds the annual reporting threshold.

Solution: