cooling tower specifications

8/9/2019 Cooling Tower Specifications

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Cooling Tower Specifications

Since this is s cooling tower used in a steam power plant therefore it does not

include radiator and it is called Open System Evaporative Cooling.

Condition:

Design of Unit 1 & 2 (4MW each)

(From H.B. STA. MARIA, THERM!"#AMI$S II B%&

Mass of led Stea! in Condenser"ṁSC

ṁSC =(1−m1−m2 )ṁS

¿ (1−0.0422−0.2659 )(1.8896 kgsec )

ṁSC =1.3074 kg

sec

#eat $e%ected in the Condenser"Q R

Q R=ṁSC (h4−h5 )


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¿1.3074 kg

sec (2304.83−163.4 )

kJ

kg

Q R=2804.9352 kW

ig're refer to # ST M$*" $efrigeration & ir Conditioning oo+

($,M $-D-$*C. T M,$S-" //- ,,. page 102

Fan 'ower is t(picall(

3.75hp

1000 kg

min cooled water

SSUM-:

Temperature differential int 3∧t 2 of 3 ℃ and )**+ outgoing humidit( t 4=27℃ ,

li-e human s-in.

$ooling tower to e used is forced draft with an efficienc( of /*+


3/29

The condition of air entering ist DB=20 ℃∧50 humidity

C,,*3 -*C*-C"ɳ C

ɳ C =t a−t b

t a−t w; @ psychometic chact ! =50 ; t DB=20 ℃thet WD=14 ℃

0here1

t a=tempeatue of point 3

t b=tempeatue of point 4

t w=wet bu"b tempeatue of ai @ point 1


4/29

0.70=t a−27 ℃

t a−14 ℃

t a=57 ℃ ; t a=t 3

indt 2=#

t 3−t 2=3 ℃

57−t 2=3 ℃

t 2=54 ℃

#eat alance in Condenser

Q R=ṁw C pw (t 3−t 4 )

0here1 Q= $eat e%ected∈condense

ṁw=mass of watee&uiement

C pw=4.187 kJ

kg− '

2804.9352 kJ

sec=ṁw4.187

kJ

kg− ' (30 ' )


5/29

ṁw=22.3305 kg

sec

Condition of ir 5 1

2from 's(chometric chart, Fig A3)4, Morse Boo-&

p1=1.033 kg

cm2=101.325 k(a

t DB=20 ℃

t WD=14 ℃

! =50

W 1=0.0076 kgkg

h1=39.5 kJ

kg

) 1=0.842 m

3

kg

Condition of ir 52


6/29

Sincet 2=54 ℃ it cannot e located on ps(chrometric chart, then use the

con5entional e6uation1

(ro! # Sta Maria" $efrigeration and ir Conditioning oo+)

! 2= p s2

pd2

0here1

ps2=∂ (essue e*eted by the +apo

pd2= (essue satuation @54 ℃

! 2= Re"ati+e $umidity

2ro! Stea! Ta6le of .eenan and .e7es)

(d2= ( sat @54 ℃

(d2=15.02k(a

Since )**+ Humidit(, then (s2= (d2=15.02k(a

W 2=0.622 (s2

(t − (s2


7/29


8/29

VCW/ ¿ṁW + f 4

+ f 4=+ f 7 27

+ f 4=0.0010035m

3

kg

V$0'¿22.3305

kg

sec (0.0010035 m3

kg )

VCW/¿0.00224 m

3

sec

(ro! T Morse" //- oo+)

Cooling Tower $ange

$ange ¿ t a−t b

¿57−27

$ange ¿30

Cooling Tower pproach

pproach ¿ t b−t w


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¿27−14

pproach ¿13

The differentialt b−t w is also important to cooling tower si8e and cost. The

smaller the difference, the larger the tower.

#eat and Mass alance in the Cooling Tower

Mass alance"m¿−mout

ṁ3+ṁa w1=ṁ4+ṁa w2;ṁ4=ṁw=22.3305 kg

sec

ṁ3−ṁ4=ṁa ( w2−w1 )

ṁ3−22.3305=ṁa (0.1082−0.0076 )

ṁ3−22.3305=0.1006ṁa ,❶

#eat alance"Q¿−Qout

ṁ3h3+ṁa h1=ṁ4 h4+ṁa h2


10/29

(ro! Stea! Ta6le .eenan and .e7es)

h3=hf @57 ℃

h3=238.59kJ

kg

h4=h f @27 ℃

h4=113.25 kJ

kg

ṁ3 (238.59 )+ṁa (39.5 )=22.3305 (113.25 )+ṁa (335.5574 )

238.59ṁ3−2528.9291=ṁa (335.5574−39.5 )

ṁ3−10.5995=1.2409ṁa ,❷

E6uate ❶ ❷;

ṁ3−22.3305

0.1006 =

ṁ3−10.5995

1.2409

ṁ3=23.3654 kg

sec

S'6stit'teṁ3 to ❶;


11/29

23.3654−22.3305=0.1006ṁa

ṁa=10.287 kg

sec

8ol'!e of ir"Va

Va¿ṁa) 1

¿10.287 kg

sec (0.842 m3

kg )

Va¿8.6619

m3

kg

Ma+e9'p water"ṁmw

ṁmw=ṁa (W 2−W 1) ¿10.287 kg

sec (0.1082−0.0076 )

ṁmw=1.0349 kg

sec


12/29

an /ower

(fro! T Morse" //D oo+) page 102


3.75hp

1000 kg

min

Mass of 0ater $ooled¿22.3305

kg

sec

-an (owe=22.3305

kg

sec .

60 sec

1min .

3.75hp

1000 kg

min

-an (owe=5.0244hp

Capacit7 of Ma+e9'p Water /'!p"VMWP

VMW/¿ṁ /W ) - 5

) - 5=) - 4=0.0010035m

3

kg

¿1.10349 kgsec (0.0010035

m3

kg )

VMW/¿0.011

m3

sec


13/29

#eat -changer design of Unit 1 & 2 (4MW each)

(ro! .ents Mechanical -ngineer #and6oo+)

og Mean Te!perat're Difference (MTD)

0/1D=2 t a−2 t b

ln(2 t a2 t b )

9i5en1

$ondensing pressure ¿0.007 /(a

w: Temperature saturation ¿55.1℃

Te!perat're of cooling water:

t 1=enteingthe condense=27 ℃

t 2="ea+ingthecondense=54 ℃

MTD ; <

2 t a=t 3−t 1

2 t a=55.1−27


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2 t a=28.1 ℃

2 t b=t 4−t 2

2 t b=55.1−54

2 t b=1.1 ℃

0/1D=28.1−1.1

ln

(

28.1

1.1

) 0/1D=8.6408℃.1.8

0/1D=15.55 ℃

-2 U3 S.* D ., M .U3 /U U3 !ass ng condenser

3ina!it +o na lang 7'ng !ass ng stea! pano +a7a 7'n

Cooling Tower Specifications

Since this is s cooling tower used in a steam power plant therefore it does not include

radiator and it is called Open System Evaporative Cooling.


15/29

Condition:

Design of Unit 1 & 2

(From H.B. STA. MARIA, THERM!"#AMI$S II B%&

#eat $e%ected in the Condenser"Q R

Q R=ṁS (h4−h5 )

¿257.5018723 kg

sec (3352.662−359.86 )

kJ

kg

Q R=770,652.1184 kW

ig're refer to # ST M$*" $efrigeration & ir Conditioning oo+


16/29

($,M $-D-$*C. T M,$S-" //- ,,. page 102


3.75hp

1000 kg

min cooled water

SSUM-:

Temperature differential int 3∧t 2 of 3 ℃ and )**+ outgoing humidit(

t 4=27 ℃ , li-e

human s-in.

$ooling tower to e used is forced draft with an efficienc( of /*+

The condition of air entering ist DB=20 ℃∧50 humidity

C,,*3 -*C*-C"ɳ C


17/29

ɳ C =t a−t b

t a−t w; @ psychometic chact ! =50 ; t DB=20 ℃thet WD=14 ℃

0here1

t a=tempeatue of point 3 t 3 @0.06 /pa=85.94

t b=tempeatue of point 4

t w=wet bu"b tempeatue of ai @ point 1

0.70=85.94−t 4 ℃

85.94−14 ℃

t 4=35.582 ℃; t a=t 3

indt 2=#

t 3−t 2=3 ℃

85.94−t 2=3 ℃

t 2=82.94 ℃

#eat alance in Condenser

Q R=ṁw C pw (t 3−t 4 )


18/29

0here1 Q= $eat e%ected∈condense

ṁw=mass of watee&uiement

C pw=4.187 kJ

kg− '

770,652.1184 kJ

sec=ṁw 4.187

kJ

kg− ' (50.358 ' )

ṁw=3654.996304 kg

sec

Condition of ir 5 1

2from 's(chometric chart, Fig A3)4, Morse Boo-&

p1=1.033 kg

cm2=101.325 k(a

t DB=20 ℃

t WD=14 ℃

! =50

W 1=0.0076 kg

kg


19/29

h1=39.5 kJ

kg

) 1=0.842

m3

kg

Condition of ir 52

Sincet 2=82.94 ℃ it cannot e located on ps(chrometric chart, then use the

con5entional e6uation1

(ro! # Sta Maria" $efrigeration and ir Conditioning oo+)

! 2= p s2

pd2

0here1

ps2=∂ (essue e*eted by the +apo

pd2= (essue satuation @54 ℃

! 2= Re"ati+e $umidity

2ro! Stea! Ta6le of .eenan and .e7es)

(d2= ( sat @82.94 ℃


20/29

(d2=53.32k(a

Since )**+ Humidit(, then (s2= (d2=53.32k(a

W 2=0.622 (s2

(t − (s2

¿ 0.622(53.32)101.325−53.32

W 2=0.690866kg

kg

h2=C pa t 2+W 2 hg2

0here1

C pa=Specific $eat of dy ai=1.0062 kJ

kg− '

t 2=tempeatue@ point 2=82.94 ℃

hg2=entha"py of satuated steam @ t 2

hg2=2648kJ

kg (¿ steamtab"e )


21/29

h2=1.0062 (82.94 )+0.690866 (2648 )

h2=1912.867396 kJ

kg

Capacit7 of Circ'lating Water /'!p"VCWP

VCW/ ¿ṁW + f 4

+ f 4=+ f 7 35.582 ℃

+ f 4=0.0010062537 m

3

kg

V$0'¿3654.996304

kg

sec (0.0010062537 m3

kg )

VCW/¿3.677854

m3

sec

(ro! T Morse" //- oo+)

Cooling Tower $ange

$ange ¿ t a−t b

¿85.94−35.582


22/29

$ange ¿50.358 ℃

Cooling Tower pproach

pproach ¿ t b−t w

¿35.582−14

pproach ¿21.582 ℃

The differentialt b−t w is also important to cooling tower si8e and cost. The smaller

the difference, the larger the tower.

#eat and Mass alance in the Cooling Tower

Mass alance"m¿−mout

ṁ3+ṁa w1=ṁ4+ṁa w2;ṁ4=ṁw=3654.996304 kg

sec

ṁ3−ṁ4=ṁa ( w2−w1 )

ṁ3−3654.996304=ṁa (0.690866−0.0076 )

ṁ3−3654.996304=0.683266ṁa ,❶


23/29

#eat alance"Q¿−Qout

ṁ3h3+ṁa h1=ṁ4 h4+ṁa h2

(ro! Stea! Ta6le .eenan and .e7es)

h3=hf @85.94 ℃

h3=360kJ

kg

h4=hf @35.582 ℃

h4=149.02276 kJ

kg

ṁ3 (360 )+ṁa (39.5 )=3654.996304 (149.02276 )+ṁa (1912.867396 )

360ṁ3−544677.637=ṁa (1912.867396−39.5 )

ṁ3−1512.993436=5.203798322ṁa ❷

E6uate ❶ ❷;

ṁ3−3654.996304

0.683266 =

ṁ3−1512.993436

5.203798322


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ṁ3=3978.754133 kg

sec

S'6stit'teṁ3 to ❶;

3978.754133−3654.996304=0.683266ṁa

ṁa=473.8386357 kg

sec

8ol'!e of ir"Va

Va¿ṁa ) 1

¿473.8386357 kg

sec (0.842 m3

kg )

Va¿398.9721312

m3

kg

Ma+e9'p water"ṁmw

ṁmw=ṁa (W 2−W 1) ¿473.8386357 kg

sec (0.690866−0.0076 )


25/29

ṁmw=323.7578293 kg

sec

an /ower

(fro! T Morse" //D oo+) page 102


3.75hp

1000 kg

min

Mass of 0ater $ooled¿3654.996304

kg

sec

-an (owe=3654.996304 kg

sec .

60 sec

1min .

3.75hp

1000 kg

min

-an (owe=822.3741684hp

Capacit7 of Ma+e9'p Water /'!p"VMWP

VMW/¿ṁ /W ) - 5

) - 5=) - 4=0.0010062537 m

3

kg


26/29

¿323.7578293 kg

sec (0.0010062537 m3

kg )

VMW/ ¿0.3257825136 m

3

sec

#eat -changer design of Unit 1 & 2 (4MW each)

(ro! .ents Mechanical -ngineer #and6oo+)

og Mean Te!perat're Difference (MTD)

0/1D=2 t a−2 t b

ln(2 t a2 t b )

9i5en1

$ondensing pressure ¿0.007 /(a

w: Temperature saturation ¿55.1

Te!perat're of cooling water:

t 1=enteingthe condense=27 ℃

t 2="ea+ingthecondense=54 ℃

MTD ;


27/29

2 t a=t 3−t 1

2 t a=55.1−27

2 t a=28.1 ℃

2 t b=t 4−t 2

2 t b=55.1−54

2 t b=1.1 ℃

0/1D=28.1−1.1

ln( 28.11.1 )

0/1D=8.6408℃.1.8

0/1D=15.55 ℃


28/29


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cooling tower specifications

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