ThehomeworkofAirPollutionControl

14.2Considerthefollowingpilot-plantdataforcontrollingethanolemissionsbybiofiltration.Thegasflowwas15m3/min,T=28C.Beddimension=3m×2m×1m(deep)

Cj，ppm

Efficiency,%

200

98

300

98

350

98

400

98

450

89

500

81

550

74

600

68

650

63

Solution:

First,calculatetheEBRT,surfaceloading,andvolumeloading.

EBRT=(3m×2m×1m)/15m3/min=0.40min

SL=5m3/min/（3m×2m）=0.83m/min

VL=1/EBRT=2.5min-1

Next,foreachdatapoint,calculatetheinletconcentration(ing/m3)usingtheidealgaslaw,andthemassvolumeloadingandeliminationcapacity.

Cj，ppm

Cj，g/m3

Effic,%

MLV/m3-hr

EC,g/m3-hr

200

0.3723

98

55.84

54.72

300

0.5584

98

83.76

82.08

350

0.6515

98

97.72

95.76

400

0.7446

98

111.68

109.45

450

0.8376

89

125.64

111.82

500

0.9307

81

139.60

113.08

550

1.0237

74

153.56

113.63

600

1.1168

68

167.52

113.91

650

1.2099

63

181.48

114.33

14.3Awhiskeydistilleryemitsairwith400ppmethanol.Theairflowsoutseveralroofventsatatotalflowrateof2000m3/min(35Cand1atm).Thedistilleryisrequiredtocollectalltheventedairandrouteittoabiofiltertocontroltotalemissionstolessthan50kgofethanolperday.Calculatetherequiredcontrolefficiency.

Solution:

Thetotalemission:50kg/day×day/(24×60min)=0.0347kg/min

Theinletethanol:

So:

EnvironmentalEngineering1001

單玉龍YulongShan

21.3Solution:

Themake-upairflowrateisselectedbasedonASHRAEguidelines.

FromASHRAE1999,wecangetthatforanormalrestaurantthatallowssmoking,theoutdoorairrequiredis30cfmpp(cubicfeetperminuteperperson).

Thus,therequiredventilationrateis

Ventilationrate=30cfmpp×150p=4500cfm

Thesame,foranonsmokingrestaurant,theoutdoorairrequiredis20cfmpp(cubicfeetperminuteperperson).

Thus,therequiredventilationrateis

Ventilationrate=20cfmpp×150p=3000cfm

21.9Solution:

(a)TheambientCOconcentrationandtheinitialindoorconcentrationofCOarebothzero.

Assumingtherewasnoremovalreaction(k=0),

V=6000ft3=169.9m3A=0.75=4/3

Whent=1h,Ci=190mg/m3

So:S=45885.5mg/hr=764.8mg/min

（b）fort=2hThen:

21.10Solution：

Tostartthenumericalsolution,westartbyrewritingthematerialbalanceasafinitedifferenceequation,eliminatingthosetermthatdonotapply:

Defining△tas1min，seeFig.1forthegraphofCOconcentrationversustime

Fig.1SpreadsheetsolutiontoProblem21.10

FromFig.1wecangettheinformationneeded:

(a)Itwilltakeonly2minutesbeforetheCOconcentrationreachestheNAAQSof40mg/m3;

(b)Itwilltake35minutesbeforetheCOcon