CHIMNEY H=211.

19 m

1. If the actual draft required

for a furnace is 6.2 cm of water 2. The density of a gas in
and the friction losses in the stack chimney is 0.79 kg/m3 and the
is 12% of theoretical draft, density of air is at atmospheric.
calculate the required stack height Determine the computed height of
in meters. Assume that the flue the chimney if the driving
gas have an average temperature temperature is 0.23 kpa.
of 149°C and molecular weight of
30. Assume air temperature of
21°C. hw =H ( ρa− ρg )

hw =6.2+ 0.12 hw KN 9.81 KN

9.81
0. 23
m2
=H (1.2−0.79 ) (
1000 m3 )
hw =7.05 cm H 2 O
(
100
KPa ) H=57.18 m
1 cm H 2 O
3. The DENR is very strict in
hw =0.691 KP a terms of air pollution. The height
of the chimney’s is by then
m P regulated to be at 65m to 100m.
=
V RT Compute the mean draft pressure
if the gas density is determined to
101.325
¿ be at 0.91 kg/m3.
0.287(21+273)
hw =H ( ρa− ρg )
kg
¿ 1.2 3
m 9.81
hw =100 ( 1.2−0. 91 ) ( 1000 )
hw =0.284 KP a
m P
=
V RT hw =H ( ρa− ρg )
101.325 9.81
¿
8.314
(149+273)
hw =65 (1.2−0. 91 ) ( 1000 )
30
hw =0.185 KP a
kg h +h
¿ 0.866 3 h´w = w1 w 2
m 2

hw =H (ρa− ρg ) 0.284 +0.185

h´w =
2
KN 9.81 KN
0.691
m 2 ( )
=H (1.2−0.866 )
1000 m 3 h´w =235 P a
4. A steam generator uses 6. In a steam power plant, 5 kg
1800 kilogram of coal per hour. If of coal is consumed per second
ash loss is 11% while the air-fuel and it was later found that 25 kg of
ratio is 15 kg/kg, determine the
dry flue gas is produced per kg of
mass of gas entering the chimney.
coal fired. Air enters at 25°C. The
ma +mf =mash +mg average temperature of the flue
15 ( 1800 )+ 1800=0.11 ( 1800 )+ m g gas inside the chimney is 250°. A
draft of 5 cm of water at the base
kg
mg=28602 of the chimney is needed. The
hr
gage fluid specific volume is
0.0025m3/ kg. if the molecular
weight of the gas is 30, calculate
the height of the chimney.

5. If the air required for

combustion is 20 kg per kg of coal
and the boiler uses 3000 kg of coal 7. A 15 kilograms enters a
per hour, determine the mass of chimney at 10m/s. is the
gas entering the chimney. Assume temperature and pressure of a gas
an ash loss of 15%. are 26°C and 100kpa respectively,
what is the diameter of the
ma +mf =mash +mg chimney?
20 ( 30 00 ) +30 00=0. 15 ( 30 00 ) +mg

kg PV =mRT
mg=62550
hr 10 0 V =15 ( 0.287 ) ( 26+273 )
m3
V =12 . 87
s
Q= AV
m3 π 2 m
12.87 = d 10
s 4 ( )( )
s

d=1.28 m

8. The DENR is very strict in

terms of air pollution. The height
of chimney’s is by then regulated and it was later found that 25 kg of
to be at 65m to 100m. Compute the dry flue gas is produced per kg of
maximum draft pressure in kg/cm2 coal fired. Air enters at 25°C. the
if the gas density is determined to average temperature of the flue
be at 0.88kg/m3. gas inside the chimney is 250°C. A
draft of 5 cm of water at the base
hw =H (ρa− ρg )
of the chimney is needed. The
hw =100 ( 1.2−0. 88 ) gage fluid specific volume is
0.0025m3/kg. If the molecular
kg m2
hw =32 (
m2 1002 cm2 ) weight of the gas is 30, calculate
the volumes of flue gas assuming
kg
hw =0.0032 an ash loss of 12%.
c m2
P
ρg =
RT

101.325
¿
8.314
(250+273)
30

kg
¿ 0. 699
m3

m
ρ=
v

5(25)
0. 699=
v

m3
v =178.81
s

10. A 15 kilograms gas enters a

9. In a steam power plant, 5 kg chimney at 10m/s. If the
of coal is consumed per second temperature and pressure of a gas
are 26°C and 100 Kpa respectively, Determine the chimney diameter if
what is the theoretical draft the mass of flue gas is 70000
pressure of the chimney? Express pounds per hour.
in Kpa.
PV =mRT
lb 1hr 1 kg
hw (
99 V = 70,000
hr )( 3600 s )( 2.205 lb )
√
V= 2g
( )
ρg KJ
(0.288 KgK ) ( 25.8+273 ) K
hw m3
10
0.4 √
= 2(9.81) (
100
0.287(26+ 273)

kg 0.00981 KN
)
V =7.67
Q= AV
m3 π 2
s 4
s

( )
7.67 = d ( 8 )
hw =37.12 2
m (
1 Kg ) d=1. 105 m

hw =0.364 KP a 12. The pressure of a certain

gas is 80Kpa and the temperature
is at 21°C. The theoretical velocity
is 12.5 m/s. Determine the required
diameter if the miss flow gas is
40,000kg per hour.

PV =mRT
40,000
80 V = ( 0.287 ) ( 21+ 273 )
3600
m3
V =11.72
s
Q= AV
m3 π 2
s ( )
11.72 = d ( 12.5 ( 0.4 ) )
4
d=1.728 m

13. A 15 kilograms gas enters a

11. The actual velocity of gas chimney at 10m/s. if the
entering in a chimney is 8m/s. The temperature and pressure of a gas
gas temperature is 25.8°C and are 26C and 100kpa respectively,
pressure of 99Kpa with a gas determine the frictional draft if the
constant of 0.288KJ/KgK. actual draft us 200Pa.
 m P pressure of 98kpa. Assuming an
=
V RT ash loss of 10% and allowable gas
100 velocity if 7.5m/s, find the diameter
¿
0.287(26+273) of chimney?

kg ma +mf =mash +mg

¿ 1.17
m3
2500+14 (25 00)=0. 1 ( 25 00 ) + mg
h
V =2 g w
2
ρg ( ) mg=37250
kg 1 hr
( )
hr 3600 s
10
2
h
( ) 0.4
=2 ( 9.81 ) w
1.17 ( ) mg=10.3 5

kg 9.81 KN PV =mRT
(
hw = 37.12
m2 )( 1 kg ) 98 V =10.35 ( 8.314
10 )
( 250+273 )

hw =364.16 Pa m3
V =45.91
s
hw =ha +h f Q= AV
m3 π 2
364.16=200+ hf
( )
45.91 = d ( 7.5 )
s 4
1 KPa
hf =164.16 Pa ( 1000 Pa ) d=2 . 79 m

hf =0.164 KPa

15. A power plant situated at an

altitude having an ambient air of
14. A water tube boiler with a 98.2kpa and 22°C. Flue gas at a
heating surface of 4 square meters rate of 4kg/s enters the stack at
uses 2500kg of coal per hour. The 180°C and leaves at 150°C. The
flue gas temperature is 250°C and flue gases gravimetric analysis are
with molecular weight of 10. The 18%CO2, 6%O2, and 76%N2.
air required for combustion is 14 Calculate the height of stack
kg per kg coal at barometric
necessary for a driving pressure hw
of 0.25kpa. V= 2g
√ ( ) ρg

220
CO2 =

O 2=
0.18
=
9
44 2200

0. 06
=
3
√
¿ 2(9.81) ( )
9.81
0 .814

m
32 16 00 V =23.24
s
0.76 19 m
N 2= = ρ=
28 700 v
¿ 0.033 7
0. 814=
v
m P
=
V RT
m3
v =8.59
98.2 s
¿
8.314 180+150

( 1
0.033 )( 2
+273 ) Q= AV
23.24
¿
0.4
¿ 0.814 m3 π

hw =H (ρa− ρg )
8.59 = d2 ¿
s 4 ( )
d=1.08 m
0.25=H ( 1.15−0.814 ) ( 19.00081 )
H=73.78 m

16. A power plant having an 17. A steam generator with

ambient air of 97.1kpa and 23°C. economizer and air heater has an
Flue gases ate a rate of 7kg/s overall draft loss of 19.6cm of
enters the smokestack at 190°C water. If stack gases are 180°C and
and leaves at 150°C. the gas if the atmosphere is at
gravimetric analysis are 17%CO2 atmospheric with 26°C
8%O2 and 75%N2. Calculate the temperature, what theoretical
diameter of stack in meters for a height of stack In meters is
driving pressure of 220Pa. needed when no draft fan are
used? Assume gas constant is the needed when the barometric
same as that of air. pressure is 29.92 inch Hg.
Determine the height of the
P
ρg = chimney.
RT
1∈¿
101.325 25.4 mm
¿ ¿
0.287(180+273) ¿
P=29.92 inHg ¿
¿ 0.77 9
P=101.32 Kpa
P
ρg =
RT hw =H ( ρa− ρg )
101.325 2.5
¿
0.287(26+273) 994.78 ( 100 )=H ( 0.287101.32
( 33+273 ) )
¿ 1.18 −101.32
0.287(270+273)
hw =H (ρa− ρg )
H=49.38 m
9. 81 9. 81
19.6 ( )
1 00 (
=H ( 1. 18−0. 78 )
1 000 )
H=488.28 m

18. A steam boiler plant

consumes 10000kg of coal per
hour and produces 15kg dry flue
gas per kg or coal fired. Outside 19. 2.8Kg coal per second are
air temperature is 33°C, average consumed by a steam boiler plant
temperature of dry flue gas in the and produced 17.52kg of dry flue
chimney is 270°C. The gage fluid gas per kg of coal fired. The air
density 994.78Kg or cubic meter temperature outside is 31°C, the
and the theoretical draft of 2.5cm average temperature of the flue
of water at the chimney base is gases entering the chimney is
324°C and the average second. Assume an ash loss of
temperature of the flue gas in the 7%.
chimney is 270°C. The gage fluid
specific volume is 1.005x10-3 m3 ma +mf =mash +mg
per kg and theoretical draft of 3.2
cm of water at the chimney base is 4500+30 (25 00)=0. 07 ( 45 00 ) + mg
needed when the barometric kg 1 hr
pressure is atmospheric. Find the mg=139185 (
hr 3600 s )
diameter of the chimney in meters.
Assume molecular weight of 30. kg
mg=38.66
s
P
ρg =
RT
101.325
¿
8.314
(270+ 273)
30
¿ 0.673

hw
V= 2g
√ ( )
ρg

√
3.2 1

¿ 2(9.81)(( 100 0.001005 )

)( )
0. 673

m
V =30.46
s

Q= A V

17.52(2.8) π 2
0.673 4 ( )
= d ( 0. 4 ( 30.46 ) )

d=2.76 m 21. In a steam power plant, 5 kg

20. If the air required for of coal is consumed per second
combustion is 30 kg per of coal and it was later found that 25kg of
and the boiler uses 4500kg of coal dry flue gas is produced per kg of
per hour, determine the mass of coal fired. Air enters at 25°C. The
gas entering the chimney in kg per average temperature of the flue
gas inside the chimney is 250°C. A installed, what is the height of the
draft of 5 cm of water at the base chimney? Use gas constant of
of the chimney is needed. The 0.277KJ/kgK.
gage fluid specific volume is
hw =H ( ρa− ρg )
0.0025m3/kg. If the molecular
weight of the gas is 30, calculate 400
the diameter of the chimney.
1000 ( 100 )0 =H ( 0.287101.32
(26 +273 ) )

P −101.32
ρg =
RT 0.27 7 (25 0+273)
101.325 H=830.99 m
¿
8.314
(250+ 273)
30
23. What is the height of the
¿ 0.699
chimney if the driving pressure is
hw 500Pa and the gas and air
V= 2g
√ ( )
ρg densities are 2kg/m3 and 2.8kg/m3
respectively?

√
5 1

¿ 2(9.81)(( 100 )( 0.0025 )

) hw =H ( ρa− ρg )

0 .699

m
500 ( 1001 )=H ( 2.8−2) ( 0.00981
1 )
V =23.69
s H=63.71 m

Q= A V

5 (25) π 2
0.699 4 ( )
= d ( 0.4 ( 23.69 ) )

d=4.9 m

24. A 16 kilograms gas enters a

22. The overall draft loss of chimney at 10m/s. If the
steam generating unit is 400mm temperature and pressure of a gas
H2O. Air enters at 101.325Kpa, are 26°C and 100Kpa respectively,
26°C and the average flue gas determine the volume of the gas.
temperature is found to be to be
250°C, if no draft fans are to be PV =mRT
 100 V =16 ( 0.287 )( 26+273 ) gas is 260°C. The gage fluid
3
m density is 995.68kg per cubic
V =13.73
s
meter and the theoretical draft of
25. A steam generator with a 2.157cm of water at the chimney
economizer and air heater has an base is needed when the
overall draft loss of 21.78cm of
water. If stack gases are at 177°C barometric pressure is 1.033kg/m2.
and if the atmosphere is at Determine the height of the
atmospheric with 26°C chimney in meters.
temperature, what theoretical
height of stack in meters is
2 2
needed when no draft fan are kg 100 cm
used? Assume gas constant is the
P=1.033
cm
2 (
m
2 () 0.00981
1 kg
KN
)
same as that of air.
KN
¿ 101.34
m2
hw =H (ρa− ρg )

1000
21.78
(100
=H ) (101.32
0.287 ( 26+273 ) )
995.68 ( 2.157
100 )=H
( 101.3 4
0.287 ( 31+273 ) )

−101. 34
−101.32
0.28 7( 260+ 273)
0.28 7(177 +273)
H=43.03 m
H=550 m

26. A steam boiler plant 27. A 150,000kg of coal supplied

consumes 8500kg of coal per hour to two boilers. One has the
and produces 19kg of flue gas per capacity of 350 kg/hr and the other
kg of coal fired. Ambient air boiler has a capacity of 100kg/hr.
temperature is 31°C and the Air fuel ratio of boilers are 15 and
average temperature of dry flue 10 respectively with ash loss of
11% to both. The pressure and cm H2O is needed at the base of
temperature of the gas as it directs the chimney and considering an
to chimney is 98kpa and 130°C. ash loss of 7%. Determine the
Use molecular weight of gas of height if the difference of their
30kg/kgmol. Determine the height densities is 25%?
of the chimney of the most
hw =H ( ρa− ρg )
consumed fuel if the draft
pressure is 2.89cm H2O. 1000 ( 3.67
100 )
=H (0.25)

hw =H (ρa− ρg ) H=146.8 m

10 00 ( 2.89
100 ) 94

( 8.314 (130+273 ) )
=H ( 1.2 )−
30

H=89.6 m

29. A steam generator

evaporated 20,000kg of water per
28. A typical steam generator
hour from feed water with enthalpy
with an efficiency of 75% is
of461.3 KJ/kg of steam with
producing 10kg/s of steam. The
enthalpy of 2706.3KJ/kg. Coal
fuel used has heating value of
consumption is 2100 kg/hr and
42,150KJ/kg. the A/F ratio by
produces 16 kg of flue gas per kg
weight is 14. Actual specific
of coal fired. The gas pressure and
evaporation is 1.2. A draft of 3.67
temperature are 97Kpa and 57°C
respectively as it enters the
310=H ( 1.2−0.99 ) ( 9.811 )
chimney at 37.7315ft/s. Determine H=150.48 m

the diameter of the chimney in

meters. 31. A fire tube boiler which has a
heating surface area of 2960 sq.ft

ma +mf =mg consumed 10000 kg of coal per

hour which produces 19kg of flue
16+2100=mg
gas per kg of coal fire. Assume an
kg 1 hr
mg=35700 (
hr 360 0 s ) ash loss of 5% determine the
volume flow rate of the gas if gas
kg
mg=9.92 pressure and temperature are
s
98Kpa and 33°C respectively.
Q= A V

PV =mRT
9.92(0.278)(57+273) π 2 37.33
97
= d
4 ( )(
3.281 ) 98 V =
10,000(19)
3600
( 0.287 )( 33+273 )
3
d=1.04 m m
V =47.296
s

32. A fire tube boiler which has a

heating surface area of 2960 sq.ft
30. The density of a gas in consumed 10000 kg of coal per
3
chimney is 0.99kg/m and the hour which produces 19kg of flue
density of air is at atmospheric. gas per kg of coal fire. The gas if
Determine the computed height of gas pressure and temperature are
the chimney if driving temperature 98Kpa and 33°C respectively.
is 310Pa. Assume an ash loss of 5%,

hw =H (ρa− ρg ) determine the diameter of the

chimney if the actual velocity is chimney if the driving pressure is
6.6m/s. 180Pa.
Q= AV
hw =H ( ρa− ρg )
m3 π 2 ( )
47.296
s ( )
= d 6.6
4 98
180=H 1.2−
( 0.287 ( 33+273 ) )( 9.811 )
d=3.02 m
H=218.15 m

34. A draft of 3.4 cm of water is

needed at the base of the chimney.
The gas temperature and pressure
are 150°F and 14.5psi,
respectively. Assume a molecular
weight of 30.2kg/kgmol. Determine
the height of the chimney.

33. A fire tube boiler which has a 150 ℉=65.56 ℃

heating surface area of 2960 sq.ft 14.5 psi=99.95 KPa

consumed 10000 kg of coal per hw =H ( ρa− ρg )

hour which produces 19kg of flue
3.4
gas per kg of coal fire. The gas if 1000 ( 100 )=H (( 1.2)− 8.314 (99.95
65.56+ 273 ) )
gas pressure and temperature are 30.2

98Kpa and 33°C respectively. H=266.34 m

Assume an ash loss of 5%,

determine the diameter of the
35. The pressure of a certain 101.325
¿
8.314
gas is 32ft of H 2O and the (137+ 273)
30
temperature is at 23°C. By design
the velocity is set to be 11m/s.
kg
¿ 0.892
Determine the chimney diameter if m
3

the mass flow rate of gas is

48,000kg per hour. Use gas m
ρ=
v
constant of 0.279KJ/kgK.
19
0. 892=
v
Q= A V
m3
v =21.31
( 48,000
3600 )
(0.279)( 23+273)
π
=( d ) ( 11 )
2
s

32
( 3.381 9.81
)( 1000 )( 1000 ) 4 hw
d=1.15 m
V= 2g
√ ( )
ρg

36. If the actual draft required

√
8.62
for a furnace is 7.5 cm of water
¿ 2(9.81)
( 100 )
( (1000 )
)
and the frictional losses in the 0.892
stack is 13% of theoretical draft. m
V =23.69
Calculate the diameter of the s

chimney if gas molecular weight is Q= A V

30, mass of 19kg/s and 137°C
m3 π 2
temperature. 21.31
s 4 ( )
= d ( 0.4 ( 43.55 ) )

hw =ha +h f d=1.25 m

hw =7.5+ 0.13 hw

hw =8.62 cm H 2 O

P
ρ=
RT
 m
V =24.13
s

Q= A V

( 82800
3600 ) π
0.789 ( 4 )
2
= d ( 0.4 ( 24.13 ) )

d=1. 96 m

38. In steam power plant, 5 kg of

37. The height of the chimney is
coal is consumed per second and
57.18m and the mass of the gas is
it was later found that 25kg of dry
82800kg per hour. Determine the
flue gas is produced per kg of coal
diameter of the chimney if the
fired. Air enters at 25°C. The
driving temperature is 0.23Kpa.
average temperature of the flue
100 gas inside the chimney is 250°C. A
0.23 KPa ( 9.81 )=2.34 cm H O 2

draft of 5cm of water at the base of

hw =H (ρa− ρg ) the chimney is needed. The gage

2.34 fluid specific volume is

1000 ( )100
=57.18 ( ( 1.2 )−ρ g )
0.0025m3/kg. If the molecular
ρg =0.78 9 weight of the gas is the same as
that of air, calculate the diameter
hw
V= 2g
√ ( )
ρg
of flue gas assuming an ash loss
of 12%.

√
2.34

¿ 2(9.81)
((100 )
( 1000 )
) ρg =
P
RT
0 .789
101.325
¿
0.287(250+273)
 ¿ 0.675 65,000
97.53 V = ( 0.287 )( 27.78+273 )
3600(2.205)

h m3
V= 2g w
ρg√ ( ) V =7.02
Q= A V
s

√
5 1

¿ 2(9.81)(( 100 0.0025 )

)( ) 22
0.675 0.4 (¿)
m3 π
V =24.11
m
s
s ( )
7.02 = d 2 ¿
4

Q= A V d=1.01 m

24.11
0.4( ¿)
12(25) π 2
0.675
= d ¿
4 ( ) 40. The theoretical velocity is
15m/s. Determine the required
d=4.94 m diameter if the mass flow of gas is
35,000kg per hour. Assume
39. The theoretical velocity of
atmospheric conditions.
gas entering in a chimney is
22m/s. The gas temperature is
Q= A V
82°F and pressure of 28.8 in Hg a
gas constant of 0.278KJ/kgK.
15
Determine the chimney diameter if 0.4(¿)
35,000 π
mas of flue gas is 65000 pounds
3600 (1.2) 4 ( )
= d2 ¿
per hour.

d=1.31 m
28.8∈Hg≈ 97.53 KP a
82 ℉=27.78 ℃

PV =mRT
 98
¿
8.314
(250+273)
30
¿ 0.676

hw
V= 2g
√ ( )
ρg

hw
7.5
0.4 √
= 2(9.81)
0.676( )
kg
hw =12.12 2
m

41. A water tube boiler with a 42. A power plant situated at an

heating surface of 4 square meters altitude having an ambient air
uses 2500kg of coal per hour. The 98.2kpa and 22°C. Flue gas at a
flue gas temperature is 250°C and rate of 4kg/s enters the stack at
with molecular weight of 30. The 180°C and leaves at 150°C. The
air required for combustion is flue gases gravimetric analysis are
14kg per kg coal at barometric 18%CO2, 6%O2 and 76%N2.
pressure of 98kpa. Assuming an Calculate the diameter of stack
ash loss of 10% and allowable gas necessary for a driving pressure
velocity of 7.5m/s, find the of 0.25Kpa.
theoretical draft. 1
m g= =30.2
0.18 0.06 0.76
+ +
P 44 32 28
ρg =
RT
P
ρg =
RT
 98.2 P
¿ ρg =
8.314 180+150 RT
( +273)
30.2 2
97 .1
¿
¿ 0.814 8.314 19 0+150
( +273)
30.2 2
hw
V= 2g
√ ( )
ρg
¿ 0.795

ρ a=
P
RT

√
1

¿ 2(9.81) ( 0.25 ( 0.00981 ) ) 97 . 1

0.814 ρ a=
0.287 ( 23+273 )
m
V =24.78 ¿ 1.14
s
Q= A V
hw =H ( ρa− ρg )

24.78 220
= H (1.14−0.795)
0.4(¿) 9.81
4 π
= d2 ¿
0.814 4 ( ) H=64.5 m

d=0.794 m

44. A steam generator with

43. A power plant having an economizer and air heater has a
ambient air 97.1Kpa and 23°C. Flue driving pressure of 250Pa. If stack
gases at a rate of 7kg/s enters the gases are at 180°C and if the
smokestack at 190°C and leaves at atmosphere is at atmospheric with
150°C. The gas gravimetric 26°C temperature, what is the
analysis are 17%CO2, 8%O2 and diameter of stack in meters?
75%N2. Calculate the height of Assume gas flow rate of 3kg per
stack in meters for a driving sec and gas constant is same as
pressure of 220Pa. air.
1
m g= =30.16
0.17 0. 08 0. 75 P
+ + ρg =
44 32 28 RT
 101.325 base is needed when the
¿
0.287(180+273)
barometric pressure is 29.92 inch
¿ 0.779
Hg. Determine the diameter of the
hw chimney.
V= 2g
√ ( )
ρg
2 9.92∈ Hg=101.32 Kp a

√
250 P
¿ 2(9.81)
( 9. 81 )
( ) ρg =
RT
0.779
101.325
¿
m 0.287(270+273)
V =25.33
s
¿ 0. 65
Q= A V

hw
25.33
0.4 (¿)
V= 2g
√ ( )
ρg

3 π
= d2 ¿ ( )
√
2.5
0.779 4
¿ 2(9.81)
(
( 100 )
(994.78)
)
0. 65
d=0.696 m
m
V =27.395
s
Q= A V

27.395
45. A steam boiler plant 0.4( ¿)
10000 (15) π 2
consumes 10000kg of coal per = d ¿
3600 (0.65) 4 ( )
hour and produces 15kg of dry
flue gas per kg of coal fired. d=2.73 m
46. 2.8kg of coal per second are
Outside air temperature is 33°C,
consumed by a steam boiler plant
average temperature of dry gas in
and produced 17.52kg of dry flue
the chimney is 270°C. The gage
gas per kg of coal fired. The air
fluid density is 994.78kg per cubic
temperature outside is 31°C, the
meter and the theoretical draft of
average temperature of the flue
2.5cm of water at the chimney
gases entering the chimney is What is the diameter of the
342°C and the average chimney if the driving pressure is
temperature of the flue gas in the 300Pa and the gas and air
chimney is 270°C. The gage fluid densities are 1kg/m3 and 1.5kg/m3,
specific volume is 1.005x10-3m3 per respectively?
kg and theoretical draft of 3.2 cm
hw
of water at the chimney base is
needed when the barometric
V= 2g
√ ( )
ρg

pressure is atmospheric. Find the

√
300
height of the chimney in meters. ¿ 2(9.81)
( 9.81 )
( ) 1
Assume molecular weight of 30.
m
V =24.49
P s
ρa= Q= A V
RT
101.325
¿
0.287(31+273) 24.49
0.4 (¿)
¿ 1.16 20,000
(17.25)
P 3600 π
ρg =
RT 1
= d2 ¿
4 ( )
101.325
¿
8.314 d=3.52 m
(270+ 273)
30
¿ 0.673

hw =H (ρa− ρg )

3.2 1
(
100 0.00 1 005 )
=H (1.16−0. 6 73)

H=65 .5 2 m

47. 20000kg of coal per hour is 48. A 15 kilograms gas enters a

being delivered to the furnace and chimney at 10m/s. If the
produces 17.25 kg of flue gas per temperature and pressure of a gas
kg of coal fired. Ash loss of 8%.
are 26°C and 10.1 m H2O, has a capacity of 100kg/hr. Air fuel
respectively. Determine the height ratio of boilers are 15 and 10
of the chimney if the driving respectively with ash loss of 11%
pressure is 2.35cm H2O. to both. The pressure and
temperature of the gas as it directs
10.1 H 2 O=99.081 KP a
to chimney is 98kpa and 130°C.
P
ρg = Use molecular weight of gas of
RT
30kg/kgmol. Determine the height
99.081
¿
0.287(26+273) of the chimney of the less
¿ 1.15 consumed fuel if the draft
P pressure is 2.79cm H2O.
ρa=
RT
hw =H ( ρa− ρg )
99.081
ρa= 2. 79 98
0.287 ( 21.11+ 273 )

¿ 1.17
100
(
(1000)=H 1. 2−
8.314
30
( 130+270 ) )
H=86.5 m
hw =H (ρa− ρg )

2.35
(1000)=H (1.17−1.15)
100
H=1224.42 m

50. A 150,000 kg of coal

supplied to two boilers. One has a
capacity of 350 kg/hr and the other
boiler has a capacity of 100 kg/hr.
Air fuel ratio of boilers are 15 and
10 respectively with an ash loss of
49. A 150,000kg of coal supplied
11% to both. The pressure and
to two boilers. One has a capacity
temperature of the gas as it directs
of 350kg/hr and the other boiler
to chimney is 98kpa and 130°C.
Use molecular weight of gas of 24.5 3
0.4( ¿)
30kg/kgmol. Determine the 10000 (15) π 2
diameter of the chimney of the ( )
= d ¿
3600 (0.65) 4
most consumed fuel if the draft
pressure is 2.79cm H2O. d=0.48 m

ma +mf =mash +mg

15 ( 35 0 ) +350=0. 011 ( 3 5 0 ) +mg

kg 1 hr
mg=5561.5 (
hr 3600 s )
kg
mg=1.54
s

P
ρg =
RT
98
¿
8.314
(130+273)
30
¿ 0. 877

hw
V= 2g
√ ( )
ρg

√
2.69

¿ 2(9.81)(( 100 )
(1000)
)
0 .877

m
V =24.5 3
s

Q= A V