Steam Power Plant Cycles

Example 6.1,Page 366

In [1]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
P1=200.0 #psia
T1=600.0 #F
P2=2.0 #psia
J=778.0

#calculations
#"from mollier charts,"
h1=1322 #Btu/lb
h2=974 #Btu/lb
vf2=0.01623 #cu ft per lb
hf2=94.0 #Btu/lb
t2=126.0 #F
Wtj=h1-h2
Qout=h2-hf2
Wp=(P1-P2)*vf2
Wpj=Wp/J
h3=hf2+Wpj
Qin=h1-h3
etat=((h1-h2)-Wpj)/(h1-(hf2+Wpj)) #efficiency
eta=((h1-h2))/(h1-(hf2)) #efficiency

#results
print round(etat*100,3),"Efficiency of rankine cycle in percent"
print round(eta*100,3)," Efficiency of rankine cycle neglecting boiler feed pump in percent"

28.339 Efficiency of rankine cycle in percent
28.339  Efficiency of rankine cycle neglecting boiler feed pump in percent

Example 6.2,Page 366

In [1]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
B=70 #F
P1=140 #psia
x=0.986
P2=14.7 #psia
ms=2000.0 #lb/hr
Ihp=80.0

#calculations
#"From mollier charts"
hc=38 #Btu/lb
hf=324.82 #Btu/lb
hfg=868.2 #Btu/lb
h1=hf+x*hfg
Qin=ms*(h1-hc)
eta=Ihp*2545*100/(Qin) #efficiency
Qw=Ihp*2545 
Qr=Qin-Qw
per=Qr/Qin *100 #percent

#results
print "Heat input to the boiler in Btu/hr",round(Qin,3)
print " Cycle efficiency in percent",round(eta,3)
print " Heat rejected to waste in Btu/hr is",round(Qr,3)," or in percent of Qin",round(per,3)
print "The answer is a bit different due to rounding off error in textbook"

Heat input to the boiler in Btu/hr 2285730.4
 Cycle efficiency in percent 8.907
 Heat rejected to waste in Btu/hr 2082130.4  or in percent of Qin 91.093
The answer is a bit different due to rounding off error in textbook

Example 6.3,Page 372

In [2]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
B=70.0 #F
P1=140.0 #psia
x=0.986
P2=14.7 #psia
ms=2000 #lb/hr
Ihp=80

#calculations
#"From mollier charts"
hc=180.0 #Btu/lb
hf=324.82 #Btu/lb
hfg=868.2 #Btu/lb
h1=hf+x*hfg
Qin=ms*(h1-hc)
eta=Ihp*2545*100/(Qin)
Qw=Ihp*2545 #Btu/hr
Qr=Qin-Qw #Btu/hr
per=Qr/Qin *100 #percent

#results
print "Heat input to the boiler in Btu/hr",round(Qin,3)
print " Cycle efficiency in percent",round(eta,3)
print " Heat rejected to waste in Btu/hr is",round(Qr,3)," or in percent of Qin",round(per,3)
print "The answer is a bit different due to rounding off error in textbook"

Heat input to the boiler in Btu/hr 2001730.4
 Cycle efficiency in percent 10.171
 Heat rejected to waste in Btu/hr 1798130.4  in percent of Qin 89.829
The answer is a bit different due to rounding off error in textbook

Example 6.4,Page 380

In [10]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
m=1.24 #lb
HV=11300 #Btu/lb

#calculations
HR=m*HV
eff=3413/HR #efficiency

#results
print "Plant heat rate in Btu/kw hr",round(HR,3)
print " Overall efficiency in percent",round(eff*100,3)

Plant heat rate in Btu/kw hr 14012.0
 Overall efficiency in percent 24.358