Chapter 8: Vapor Power Cycle¶

Example 1, page no. 275¶

In [1]:
from __future__ import division

#Variable Declaration:
p1 = 7 #Lower pressure limit(in kPa):
p2 = 7 #Higher pressure limit(in MPa):
h2 = 2772.1 #Enthalpy at state 2(in kJ/kg):
s2 = 5.8133 #Entropy at state 2(in kJ/kg.K):
h3 = 1267 #Enthalpy at state 3(in kJ/kg):
s3 = 3.1211 #Entropy at state 3(in kJ/kg.K):
sf1 = 0.5564 #Value of sf at 7 kPa(in kJ/kg.K):
sfg1 = 7.7237 #Value of sfg at 7 kPa(in kJ/kg.K):
hf1 = 162.60 #Value of hf at 7 kPa(in kJ/kg):
hfg1 = 2409.54 #Value of hfg at 7 kPa(in kJ/kg):
s1 = s2 #Entropy at state 1(in kJ/kg.K):

#Calculations:
x1 = (s1-sf1)/sfg1 #Dryness fraction at state 1:
h1 = hf1+x1*hfg1 #Enthalpy at state 1(in kJ/kg):
s4 = s3 #Entropy at state 4(in kJ/kg.K):
x4 = (s4-sf1)/sfg1 #Dryness fraction for state 4:
h4 = hf1+x4*hfg1 #Enthalpy at state 4(in kJ/kg):
W1 = h2-h1 #Expansion work per kg(in kJ/kg):
W2 = h3-h4 #Compression work per kg(in kJ/kg):
H = h2-h3 #Heat added per kg(in kJ/kg):
W = W1-W2 #Net work done(in kJ/kg):
n = W/H #Thermal efficiency:

#Results:
print  "Thermal Efficiency: ",round(n*100,2),"%"
print  "Turbine work: ",round(W1,2),"KJ/Kg"
print  "Compression work: ",round(W2,2),"KJ/Kg"

Thermal Efficiency:  44.2 %
Turbine work:  969.52 KJ/Kg
Compression work:  304.3 KJ/Kg


Example 2, page no. 276¶

In [4]:
from __future__ import division

#Variable Declaration:
p1 = 5        #Lower pressure limit(in kPa):
p2 = 5000 #Higher pressure limit(in kPa):
#From gas tables:
hf5M = 1154.23 #Value of hf at 5 MPa(in kJ/kg):
sf5M = 2.92 #Value of sf at 5 MPa(in kJ/kg.K):
hg5M = 2794.3 #Value of hg at 5 MPa(in kJ/kg):
sg5M = 5.97 #Value of sg at 5 MPa(in kJ/kg.K):
hf5k = 137.82 #Value of hf at 5 kPa(in kJ/kg):
sf5k = 0.4764 #Value of sf at 5 kPa(in kJ/kg.K):
hg5k = 2561.5 #Value of hg at 5 kPa(in kJ/kg):
sg5k = 8.3961 #Value of sg at 5 kPa(in kJ/kg.K):
vf5k = 0.001005 #/Value of vf at 5 kPa(in m**3/kg):

#Calculation:
sfg5k = sg5k-sf5k #Value of sfg at 5 kPa(in kJ/kg.K):
hfg5k = hg5k-hf5k #Value of hfg at 5 kPa(in kJ/kg.K):
s2 = sg5M #Entropy at point 2(in kJ/kg.K):
s3 = s2         #As process 2-3 is isentropic:
x3 = (s3-sf5k)/sfg5k #Dryness fraction at point 3:
h3 = hf5k+x3*hfg5k #Enthalpy at point 3(in kJ/kg):
h2 = hg5M #Enthalpy at point 2(in kJ/kg):
s1 = sf5M #Entropy at point 1(in kJ/kg.K):
s4 = s1  #Process 1-4 is isentropic:
x4 = (s4-sf5k)/sfg5k #Dryness fraction at point 4:
h4 = hf5k+x4*hfg5k #Enthalpy at point 4(in kJ/kg):
h1 = hf5M #Enthalpy at point 1(in kJ/kg):
n = ((h2-h3)-(h1-h4))/(h2-h1) #Carnot efficiency:
Pw = vf5k*(p2-p1) #Pump work:
h5 = hf5k #Enthalpy at point 5(in kJ/kg):
h6 = h5+Pw #Enthalpy at point 6(in kJ/kg):
Nw = (h2-h3)-(h6-h5) #Net work in the cycle:
nr = Nw/Ha #Rankine efficiency:

#Results:
print "Carnot cycle efficiency: ",round(n*100,2)
print "Rankine cycle efficiency: ",round(nr*100,2)

Carnot cycle efficiency:  43.09
Rankine cycle efficiency:  36.59


Example 3, page no. 278¶

In [7]:
from __future__ import division

#Variable Declaration:
p1 = 40 #Pressure of steam entering(in bar):
T1 = 350+273    #Temperature(in K):
p4 = 0.05  #Pressure of steam leaving(in bar):
#From steam tables:
h2 = 3092.5                 #kJ/kg
s2 = 6.5821                 #kJ/kg.K
h4 = 137.82                 #kJ/kg
s4 = 0.4764                 #kJ/kg.K
v4 = 0.001005               #m**3/kg
sf = 0.4764                 #kJ/kg.K
sfg = 7.9187                #kJ/kg.K
hf = 137.82                 #kJ/kg
hfg = 2423.7                #kJ/kg

#Calculations:
s3 = s2  #Entropy at state 3:
x3 = (s3-sf)/sfg            #Dryness fraction at state 3:
h3 = hf+x3*hfg  #Enthalpy at state 3(in kJ/kg):
h1 = h4+v4*(p1-p4)*10**2    #Enthalpy at state 1(in kJ/kg):
Wp = h1-h4 #Pump work(in kJ/kg):
Wnet = h2-h3-Wp  #Net work(in kJ/kg):
Q = h2-h1 #Heat added(in kJ/kg):
n = Wnet/Q*100   #Cycle efficiency(in kJ/kg):

#Results:
print "Net work per kg of steam: ",round(Wnet,2),"kJ/kg"
print "Cycle efficiency: ",round(n,2),"%"
print "Pump work per kg of steam: ",round(Wp,2),"kJ/kg"

Net work per kg of steam:  1081.88 kJ/kg
Cycle efficiency:  36.67 %
Pump work per kg of steam:  4.01 kJ/kg


Example 4, page no. 279¶

In [11]:
from __future__ import division

#Variable Declaration:
p1 = 20  #Pressure of the steam entering(in MPa):
T1 = 500+273   #Temperature(in K):
x = 0.90  #Dryness fraction of the steam leaving:
p6 = 0.005 #Condensor pressure(in MPa):
#From steam tables:
h2 = 3238.2                 #kJ/kg
s2 = 6.1401                 #kJ/kg.K
s3 = s2
hf = 137.82                 #kJ/kg
hfg = 2423.7                #kJ/kg.K
sf = 0.4764                 #kJ/kg.K
sfg = 7.9187                #kJ/kg.K
h6 = 137.82                 #kJ/kg
h4 = 3474.1                 #kJ/kg
sf1 = 2.2842                #kJ/kg.K
sfg1 = 4.1850               #kJ/kg.K
hf1 = 830.3                 #kJ/kg
hfg1 = 1959.7               #kJ/kg
v6 = 0.001005               #m**3/kg

#Calculations:
h5 = hf+x*hfg #Enthalpy at state 5(in kJ/kg):
s5 = sf+x*sfg
p4 = 1.4 #By interpolation, pressure at state 4(in bar):
x3 = (s3-sf1)/sfg1  #Dryness fraction at state 3:
h3 = hf1+x3*hfg1 #Enthalpy at state 3(in kJ/kg):
h1 = h6+v6*(p1-p6)*10**3    #Enthalpy at state 1(in kJ/kg):
Wnet = (h2-h3)+(h4-h5)-(h1-h6) #Net work per kg of steam(in kJ/kg):
Q = h2-h1 #Heat added per kg of steam(in kJ/kg):
n = Wnet/Q*100  #Thermal efficiency:

#Results:
print "Pressure of steam leaving HP turbine: ",round(p4,2),"MPa"
print "Thermal efficiency: ",round(n,2),"%"

Pressure of steam leaving HP turbine:  1.4 MPa
Thermal efficiency:  56.4 %


Example 5, page no. 280¶

In [14]:
from __future__ import division

#Variable Declaration:
p1 = 10 #Pressure of steam leaving the boiler(in MPa):
T1 = 700+273 #Temperature(in K):
p4 = 0.005 #Pressure of steam leaving the turbine(in MPa):
W = 50 #Output of the plant(in MW):
Twin = 15+273 #Temperature of the cooling water entering and leaving the condensor(in K):
Twout = 30+273
#From steam tables:
h2 = 3870.5             #kJ/kg
s2 = 7.1687             #kJ/kg.K
sf = 0.4764             #kJ/kg.K
sfg = 7.9187            #kJ/kg.K
hf = 137.82             #kJ/kg
hfg = 2423.7            #kJ/kg
v4 = 0.001005           #m**3/kg
Cp = 4.18 #Specific heat of water(in kJ/kg.K):

#Calculations:
s3 = s2
h4 = hf
x3 = (s3-sf)/sfg #Dryness fraction at state 3:
h3 = hf+x3*hfg #Enthalpy at state 3(in kJ/kg):
h1 = h4+v4*(p1-p4) #Enthalpy at state 1(in kJ/kg):
Wnet = (h2-h3)-(h1-h4) #Net output per kg of steam(in kJ/kg):
ms = W*10**3/Wnet #Mass flow rate of steam(in kg/s):
mw = (h3-h4)*ms/(Cp*(Twout-Twin))#Mass flow rate of water(in kg/s):
Q = h2-h1 #Heat added per kg of steam(in kJ/kg):
n = Wnet/Q #Thermal efficiency:
r = (h2-h1)/(h3-h4)	#Ratio of heat supplied:

print "Mass flow rate of steam: ",round(ms,2),"kg/s"
print "Mass flow rate of condensor cooling water: ",round(mw,2),"kg/s"
print "Thermal efficiency: ",round(n*100,2),"%"
print "Ratio of heat supplied and rejected: ",round(r,3)

Mass flow rate of steam:  29.69 kg/s
Mass flow rate of condensor cooling water:  969.78 kg/s
Thermal efficiency:  45.12 %
Ratio of heat supplied and rejected:  1.822


Example 6, page no. 282¶

In [15]:
from __future__ import division

#Variable Declaration:
p1 = 200  #Pressure of steam leaving the boiler(in MPa):
T1 = 650+273 #Temperature(in K):
p4 = 0.05  #Pressure of steam leaving the turbine(in MPa):
#From steam tables:
h2 = 3675.3                 #kJ/kg
s2 = 6.6582                 #kJ/kg.K
h4 = 137.82                 #kJ/kg
v4 = 0.001005               #m**3/kg
sf = 0.4764                 #kJ/kg.K
sfg = 7.9187                #kJ/kg.K
hf = 137.82                 #kJ/kg
hfg = 2423.7                #kJ/kg
hf8 = 721.11                #kJ/kg
hfg8 = 2048                 #kJ/kg
vf8 = 0.001115              #m**3/kg
sf8 = 2.0462                #kJ/kg.K
sfg8 = 4.6166               #kJ/kg.K
T10 = 370.36+273            #K(by interpolation)
h10 = 3141.81               #kJ/kg
sf4 = 1.7766                #kJ/kg.K
sfg4 = 5.1193               #kJ/kg.K
hf4 = 604.74                #kJ/kg
hfg4 = 2133.8               #kJ/kg
s3 = s2
s6 = s2  #For case b:
s10 = s2    #For case c:
s9 = s2
h11 = hf4
h13 = 1087.31               #kJ/kg
v11 = 0.001084              #m**3/kg
v13 = 0.001252              #m**3/kg
p10 = 40                    #bar
p9 = 4                      #bar

#Calculations:
#Case a:
x3 = (s3-sf)/sfg  #Dryness farction at state 3:
h3 = hf+x3*hfg #Enthalpy at state 3(in kJ/kg):
h1 = h4+v4*(p1-p4)   #Enthalpy at state 1(in kJ/kg):
Wnet = (h2-h3)-(h1-h4)    #Net output per kg of steam(in kJ/kg):
Q = h2-h1   #Heat added(in kJ/kg):
na = Wnet/Q*100    #Thermal efficiency:
#Case b:
x6 = (s6-sf8)/sfg8   #Dryness fraction at state 6(in kJ/kg.K):
h6 = hf8+x6*hfg8   #Enthalpy at state 6(in kJ/kg):
h7 = hf8   #Enthalpy at state 7(in kJ/kg):
h5 = h4+v4*(p1-p4)*10**2    #Enthalpy at state 5(in kJ/kg):
m = (h7-h5)/(h6-h5)	    #Mass of steam(in kg):
h1 = h7+vf8*(p1-p4)*10**2   #Enthalpy at state 1(in kJ/kg):
nb = ((h2-h6)+(1-m)*(h6-h3)-((1-m)*(h5-h4)+(h1-h7)))/(h2-h1)*100 #Thermal efficiency:
#Case c:
x9 = (s9-sf4)/sfg4    #Dryness fraction at state 9:
h9 = hf4+x9*hfg4  #Enthalpy at state 9(in kJ/kg):
h8 = h4+v4*(p9-p4)*10**2    #Enthalpy at state 8(in kJ/kg):
h12 = h11+v11*(p10-p9)*10**2#Enthalpy at state 12(in kJ/kg):
h1a = h13+v13*(p1-p10)*10**2#Enthalpy at state 1'(in kJ/kg):
m1 = (h13-h12)/(h10-h12)    #Mass of steam flowing through first heater:
m2 = ((1-m1)*h11-(1-m1)*h8)/(h9-h8)#Mass of steam flowing through second heater:
Wcep = (1-m1-m2)*(h8-h4)    #Work done by Condensate extraction pump(in kJ/kg):
WFP1 = h1a-h13 #Work done by feed pump 1(in kJ/kg):
WFP2 = (1-m1)*(h12-h11)   #Work done by feed pump 2(in kJ/kg):
nc = ((h2-h10)+(1-m1)*(h10-h9)+(1-m1-m2)*(h9-h3)-(Wcep+WFP1+WFP2))/(h2-h1a)*100	#Thermal efficiency:

#Results:
print "Thermal efficiency in case a: ",round(na,2),"%"
print "Thermal efficiency in case b: ",round(nb,2),"%"
print "Thermal efficiency in case c: ",round(nc,2),"%"

Thermal efficiency in case a:  46.51 %
Thermal efficiency in case b:  49.4 %
Thermal efficiency in case c:  51.39 %


Example 7, page no. 287¶

In [18]:
from __future__ import division

#Variable Declaration:
p1 = 50 #Pressure at which steam is generated(in bar):
T1 = 500+273 #Temperature of the steam(in K):
p3 = 5 #Pressure upto which steam is expanded(in bar):
T3 = 400+273 #Temperature(in K):
p5 = 0.05 #Final pressure(in bar):
#From steam tables:
h2 = 3433.8     #kJ/kg
s2 = 6.9759     #kJ/kg.K
s3 = s2
T3 = 183.14+273 #K(by interpolation)
h3 = 2818.03    #kJ/kg
h4 = 3271.9     #kJ/kg
s4 = 7.7938     #kJ/kg.K
s5 = s4
sf = 0.4764     #kJ/kg.K
sfg = 7.9187    #kJ/kg.K
hf = 137.82     #kJ/kg
hfg = 2423.7    #kJ/kg
h6 = hf
v6 = 0.001005   #m**3/kg

#Calculations:
x5 = (s5-sf)/sfg #Dryness fraction at state 5:
h5 = hf+x5*hfg #Enthalpy at state 5(in kJ/kg):
h1 = h6+v6*(p1-p5)*10**2#Enthalpy at state 1(in kJ/kg):
Wt = (h2-h3)+(h4-h5) #Turbine work(in kJ/kg):
Wp = h1-h6 #Pump work(in kJ/kg):
Wnet = Wt-Wp #Net output per kg of steam(in kJ/kg):
Q = h2-h1 #Heat added per kg of steam(in kJ/kg):
n = Wnet/Q #Cycle efficiency:
ssc = 0.7457*3600/Wnet #Specific steam consumption(in kg/hp.hr):
r = Wnet/Wt #Work ratio:

#Results:
print "Cycle efficiency: ",round(n*100,2),"%"
print "Specific steam consumption: ",round(ssc,2),"kg/hp.hr"
print "Work ratio: ",round(r,4)

Cycle efficiency:  45.74 %
Specific steam consumption:  1.78 kg/hp.hr
Work ratio:  0.9967


Example 8, page no. 288¶

In [20]:
from __future__ import division

#Variable Declaration:
m = 0.144  #Mass of steam entering the feed pump(in kg):
p1 = 60 #Pressure of steam fed in HP turbine(in bar):
T1 = 450+273 #Temperature of the steam(in K):
p3 = 3 #Pressure of steam entering LP turbine(in bar):
p4 = 0.05 #Pressure of steam leaving the LP turbine(in bar):
T3 = 115 #Condensate temperature(in C):
W = 30 #Alternator output(in MW):
nb = 0.90 #Boiler efficiency:
na = 0.98 #Alternator efficiency:
#From steam tables:
h2 = 3301.8     #kJ/kg
s2 = 6.7198     #kJ/kg.K
hf = 137.82     #kJ/kg
hfg = 2423.7    #kJ/kg
vf = 0.001005   #m**3/kg
h8 = 561.47     #kJ/kg
sf3 = 1.6718    #kJ/kg.K
sfg3 = 5.3201   #kJ/kg.K
hf3 = 561.47    #kJ/kg
hfg3 = 2163.8   #kJ/kg
sf = 0.4764     #kJ/kg.K
sfg = 7.9187    #kJ/kg.K

#Calculations:
h5 = hf
v5 = vf
s3 = s2
s4 = s2
h9 = h8
v6 = v5
x3 = (s3-sf3)/sfg3                  #Dryness fraction at state 3:
x4 = (s4-sf)/sfg                    #Dryness fraction at state 4:
h3 = hf3+x3*hfg3                    #Enthalpy at state 3(in kJ/kg):
h4 = hf+x4*hfg                    #Enthalpy at state 4(in kJ/kg):
h1 = 4.18*T3                  #Enthalpy at state 1(in kJ/kg):
Wp = v5*(p1-p4)*10**2               #Pumping work(in kJ/kg) also equal to h7-h6:
Wnet = (h2-h3)+(1-m)*(h3-h4)-(1-m)*Wp#Net output(in kJ/kg):
ms = W*10**3/(na*Wnet)              #Mass of steam required to be generated(in kg/hr):
Q = (h2-h1)/nb                    #Heat added(in kJ/kg):
no = Wnet/Q*100                     #Overall thermal efficiency:

#Results:
print "Steam bled for feed heating: ",round(m,3),"kg"
print "Capacity of boiler: ",round(ms,2)*3600,"kg/hr"
print "Overall thermal efficiency: ",round(no,2),"%"

Steam bled for feed heating:  0.144 kg
Capacity of boiler:  94464.0 kg/hr
Overall thermal efficiency:  37.21 %


Example 9, page no. 290¶

In [22]:
from __future__ import division

#Variable Declaration:
p1 = 30 #Pressure of steam entering(in bar):
T1 = 300 #Temperature(in C):
p3 = 6 #Pressure of steam leaving the first stage(in bar):
p4 = 1 #Steam leaving second stage at pressure(in bar):
p5 = 0.075 #Pressure of steam leaving the third stage(in bar):
T = 38 #Condenstate temperature(in C):
T8 = 150 #Temperature of water after leaving first and second heater(in C):
T13 = 95
n = 0.8 #Efficiency of turbine:
W = 15 #Turbine output(in MW):
#From steam tables:
h2 = 3230.9                     #kJ/kg
s2 = 6.9212                     #kJ/kg.K
T3 = 190.97                     #K(by interpolation)
h3 = 2829.63                    #kJ/kg
s3a = 7.1075                    #kJ/kg.K
sf1 = 1.3026                    #kJ/kg.K
sfg1 = 6.0568                   #kJ/kg.K
hf1 = 417.46                    #kJ/kg
hfg1 = 2258                     #kJ/kg
h5 = 234.64                     #kJ/kg
hf6 = 670.56                    #kJ/kg

#Calculations:
s3 = s2
s4 = s3a
h11 = hf6
h3a = round(h2-n*(h2-h3),2) #Actual enthalpy at state 3(in kJ/kg):
x4 = round((s4-sf1)/sfg1,3) #Dryness fraaction at state 4:
h4 = hf1+x4*hfg1  #Enthalpy at state 4(in kJ/kg):
h4a = round(h3a-n*(h3a-h4),2) #Actual enthaly at state 4(in kJ/kg):
x4a = (h4a-hf1)/hfg1 #Actual dryness fraction at state 4:
s4a = sf1+x4a*sfg1 #Actual entropy at state 4(in kJ/kg.K):
s5 = s4a #Entropy at state 5(in kJ/kg.K):
x5 = 0.8735 #Dryness fraction:
h5 = 2270.43 #Enthalpy at state 5(in kJ/kg):
h5a = h4a-n*(h4a-h5) #Actual enthalpy at state 5(in kJ/kg):
m1 = 0.1293
m2 = 0.1059
Wt = (h2-h3a)+(1-m1)*(h3a-h4a)+(1-m1-m2)*(h4a-h5a)  #Turbine output(in kJ/kg):
r = W*10**3/Wt*3600 #Rate of steam generation required(in kg/hr):
c = (m1+m2)*r #Capacity of drain pump(in kg/hr):

#Results:
print "Capacity of drain pump: ",round(c,2),"kg/hr"

Capacity of drain pump:  16273.8 kg/hr


Example 10, page no. 292¶

In [24]:
from __future__ import division

#Variable Declaration:
p1 = 70 #Pressure of the steam entering(in bar):
T1 = 450 #Temperature of the steam entering the HP turbine(in C):
p3 = 30 #Pressure at which steam is extracted(in bar):
T4 = 400 #Temperature at which it is reheated(in C):
p6 = 0.075 #Pressure of steam after expanding(in bar):
T = 140 #Temperature at which steam is bled(in C):
nh = 0.80 #Efficiency of HP turbine:
nl = 0.85 #Efficiency of LP turbine:
#From steam tables:
h2 = 3287.1                     #kJ/kg
s2 = 6.6327                     #kJ/kg.K
h3 = 3049.48                    #kJ/kg
h4 = 3230.9                     #kJ/kg
s4 = 6.9212                     #kJ/kg.K
h6 = 2158.55                    #kJ/kg
p5 = 3.61                       #bar
h5 = 2712.38                    #kJ/kg
h9 = 1008.42                    #kJ/kg
v7 = 0.001008                   #m**3/kg
h7 = 168.79                     #kJ/kg
h8 = 169.15                     #kJ/kg
v9 = 0.00108                    #m**3/kg

#Calculations:
s6 = s4
s5 = s4
h3a = h2-nh*(h2-h3) #Actual enthalpy at state 3(in kJ/kg):
h6a = h4-nl*(h4-h6) #Actual enthaly at state 6(in kJ/kg):
h5a = h4-nl*(h4-h5) #Actual enthaly at state 5(in kJ/kg):
h8 = h7+v7*(p5-p6)*10**2 #Enthalpy at state 8(in kJ/kg):
m = (h9-h8)/(h5a-h8) #Mass of bled steam per kg of steam generated(in kg/kg steam generated):
h1 = h9+v9*(p1-p5)*10**2 #Enthalpy at state 1(in kJ/kg):
Wnet = (h2-h3a)+(h4-h5a)+(1-m)*(h5a-h6a)-((1-m)*(h8-h7)+(h1-h9))#Net work per kg of steam generated(in kJ/kg):
Q = (h2-h1)+(h4-h3a) #Heat added per kg of steam generated(in kJ/kg):
n = Wnet/Q*100 #Thermal efficiency:

#Result:
print "Thermal efficiency: ",round(n,2),"%"
print "___There is a calculation mistake in calculating h2-h1 in book hence difference in answer_____"

Thermal efficiency:  39.22 %
___There is a calculation mistake in calculating h2-h1 in book hence difference in answer_____


Example 11, page no. 294¶

In [26]:
from __future__ import division

#Variable Declaration:
p1 = 150 #Pressure of the steam entering the boiler(in bar):
T1 = 450 #Temperature of the steam entering the turbine(in C):
p6 = 0.05 #Condensor pressure(in bar):
p3 = 10 #Pressure of steam bled out between 1st & 2nd stage and 2nd & 3rd(in bar):
p4 = 1.5
T11 = 150 #Temperature of feed water leaving closed water heater(in C):
m = 300 #Mass flow rate(in kg/s):
#From steam tables:
h2 = 3308.6                     #kJ/kg
s2 = 6.3443                     #kJ/kg.K
h3 = 2667.26                    #kJ/kg
h4 = 2355.18                    #kJ/kg
h5 = 1928.93                    #kJ/kg
h6 = 137.82                     #kJ/kg
v6 = 0.001005                   #m**3/kg
h8 = 467.11                     #kJ/kg
v8 = 0.001053                   #m**3/kg
h10 = 1610.5                    #kJ/kg
v10 = 0.001658                  #m**3/kg

#Calculations:
s3 = s2
s4 = s2
s5 = s2
h7 = h6+v6*(p4-p6)*10**2                #Enthalpy at state 7(in kJ/kg):
h9 = round(h8+v8*(p1-p4)*10**2,2)       #Enthalpy at state 9(in kJ/kg):
h12 = round(h10+v10*(p1-p3)*10**2,2)    #Enthalpy at state 12(in kJ/kg):
m1 = round((4.18*T11-h9)/(h3-h9+4.18*T11-h10),2)#Mass of steam bled out in closed feed water heater(in kg/kg of steam generated):
m2 = round(((1-m1)*(h8-h7))/(h4-h7),2)
h1 = (4.18*T11)*(1-m1)+m1*h12   #Enthalpy at state 1(in kJ/kg):
Wnet = (h2-h3)+(1-m1)*(h3-h4)+(1-m1-m2)*(h4-h5)-((1-m1-m2)*(h7-h6)+(1-m1)*(h9-h8)+m1*(h12-h10))	#Net work output per kg of steam generated(in kJ/kg):
Q = h2-h1  #Heat added(in kJ/kg):
n = Wnet/Q*100    #Cycle thermal efficiency:
P = Wnet*m                              #Net power developed(KW)

#Results:
print "Cycle thermal efficiency: ",round(n,1),"%"
print "Net power developed: ",round(P),"kW"

Cycle thermal efficiency:  47.6 %
Net power developed:  365700.0 kW


Example 12, page no. 297¶

In [28]:
from __future__ import division

#Variable Declaration:
p1 = 100 #Pressure of the steam entering the boiler(in bar):
T1 = 500 #Temperature of the steam entering the turbine(in ºC):
p6 = 0.075 #Condensor pressure(in bar):
p3 = 20 #Pressure at which steam is extracted at exit of HPT(in bar):
p4 = 4 #Pressure at which steam is extracted at exit of IPT(in bar):
T = 200 #Temperature at which feed water leaves closed feed warere heater(in C):
W = 100 #Net power output(in MW):
#From steam tables:
h2 = 3373.7                     #kJ/kg
s2 = 6.5966                     #kJ/kg.K
T3 = 261.6                      #C(by interpolation)
h3 = 2930.57                    #kJ/kg
h4 = 2612.65                    #kJ/kg
h5 = 2055.09                    #kJ/kg
h10 = 908.79                    #kJ/kg
h8 = 604.74                     #kJ/kg
v6 = 0.001008                   #m**3/kg
h6 = 168.79                     #kJ/kg
h8 = 604.74                     #kJ/kg
v8 = 0.001084                   #m**3/kg
#For modified part:
h3a = 3247.6                    #kJ/kg
s3a = 7.1271                    #kJ/kg.K
T4 = 190.96                     #C(by interpolation)
h4a = 2841.2                    #kJ/kg
h5a = 2221.11                   #kJ/kg

#Calculations:
s3 = s2
s4 = s2
s5 = s2
h1 = 4.18*T
h11 = h10
s4a = s3a
s5a = s3a
h7 = h6+v6*(p4-p6)*10**2 #Enthalpy at state 7(in kJ/kg):
h9 = h8+v8*(p3-p4)*10**2 #Enthalpy at state 9(in kJ/kg):
m1 = (h1-h9)/(h3-h10) #Mass of steam bled out in closed feed water heater(in kg/kg of steam generated):
m2 = ((h8-h7)-m1*(h11-h7))/(h4-h7)
Wnet = (h2-h3)+(1-m1)*(h3-h4)+(1-m1-m2)*(h4-h5)-((1-m1-m2)*(h7-h6)+(h9-h8)) #Net work per steam generated(in kJ/kg):
Q = h2-h1 #Heat added(in kJ/kg):
n = Wnet/Q*100 #Thermal efficiency:
sgc = W*10**3/Wnet #Steam genration rate(in kg/s):
m2a = ((h8-h7)-m1*(h11-h7))/(h4a-h7)#Mass of steam bled out in closed feed water heater(in kg/kg of steam generated):				#For modified part:
Wneta = (h2-h3)+(1-m1)*(h3a-h4a)+(1-m1-m2a)*(h4a-h5a)-((1-m1-m2a)*(h7-h6)+(h9-h8)) #Net work per steam generated(in kJ/kg):
Qa = h2-h1+(1-m1)*(h3a-h3) #Heat added(in kJ/kg):
na = Wneta/Qa*100 #Thermal efficiency:
I = (na-n)/n*100 #% Increase in thermal efficiency due to reheating:

#Results:
print "Thermal efficiency: ",round(n,2),"%"
print "Steam generation rate: ",round(sgc,2),"kg/s"
print "Thermal efficiency: ",round(na,2),"%"
print "Percentage increase in efficiency due to reheating: ",round(I,2),"%"

Thermal efficiency:  44.8 %
Steam generation rate:  87.95 kg/s
Thermal efficiency:  45.04 %
Percentage increase in efficiency due to reheating:  0.52 %


Example 13, page no. 301¶

In [30]:
from __future__ import division

#Variable Declaration:
hd = 349    #Enthalpy of dry saturated vapour at 8.45 bar(KJ/Kg)
hi = 234.5   #Enthalpy after isentropic expansion to 0.07 bar(KJ/Kg)
hs =  35  #Enthalpy of saturated liquid at 0.07 bar (KJ/Kg)
n1 = 0.85 #Capability:
Cpw = 4.18 #Specific heat of water:
#From steam tables:
h1 = 2767.13                            #kJ/kg
h2 = 3330.3                             #kJ/kg
s2 = 6.9363                             #kJ/kg.K
h3 = 2899.23                            #kJ/kg
x4 = 0.93
h4 = 2517.4                             #kJ/kg
x5 = 0.828
h5 = 2160.958                           #kJ/kg
h6 = 168.79                             #kJ/kg
v6 = 0.001008                           #m**3/kg
h7 = 168.88                             #kJ/kg
h9 = 417.46                             #kJ/kg
h13 = 721.11                            #kJ/kg
v13 = 0.001252                          #m**3/kg
T1 = 150                                #ºC
h10 = 418.19                            #kJ/kg
m1 = 0.102
m2 = 0.073

#Calculations:
s3 = s2
s4 = s2
s5 = s2
qd = hd-hi #For mercury cycle,Isentropic heat drop:
qda = n1*qd#Actual heat drop:
qre = hd-qda-hs #Heat rejected in condenser(in kJ/kg):
qa = hd-hs #Heat added in the boiler(in kJ/kg):
qam = h1-Cpw*T1 #Heat added in the condenser of mercury cycle(in kJ/kg):
m = qam/qre #Mercury per steam required per kg of steam:
Wp = v13*(40-8)*10**2 #Pump work(in kJ/kg):
qt = m*qa+h2-h1 #Total heat supplied(in kJ/kg steam):
Wm = m*qda #Work done in mercury cycle(in kJ/kg):
Ws = (h2-h3)+(1-m1)*(h3-h4)+(1-m1-m2)*(h4-h5)-(1-m1-m2)*(h7-h6)-m2*(h10-h9)-m1*Wp#Work done in steam cycle(in kJ/hr):
Wt = Wm+Ws #Total work done(in kJ/kg):
n = Wt/qt*100 #Thermal efficiency:

#Results:
print "Thermal efficiency: ",round(n,2),"%"

Thermal efficiency:  55.36 %


Example 14, page no. 303¶

In [2]:
from __future__ import division
from sympy import symbols,solve

#Variable Declaration:
h1 = 3023.5             #KJ/Kg
s1 = 6.7664             #KJ/Kg.K
n = 0.8                 #Efficiency ratio of HP and LP
W = 0.1                 #Steam consumption at no load
P = 2500                #Pressure turbine output
mHP,cHP,mLP,cLP = symbols('mHp cHP mLP cLP')     #Symbolic expressions for  mHP,cHP,mLP,cLP respectively
LPavail = 1.5           #LP steam available(Kg/s) for getting 1000hp
DhLP = 387.49           #Actual enthalpy drop in LP(KJ/Kg)

#From Table 3
sf = 0.5764
sfg = 7.6752
hf = 168.79
hfg = 2406.0

#Calculations:
s2 = s1
x3 = round((s2 - sf)/sfg,3)
h3HP = hf + x3*hfg
DhHP = n*(h1-h3HP)      #Actual enthalpy drop in HP(KJ/Kg)
x3a = (7.1271-sf)/sfg
h3LP = hf+ x3a*hfg      #Enthalpy at exit(KJ/Kg)
HPfull = P*0.7457/DhHP  #HP steam consumption at full load(Kg/s)
HPNL = W*HPfull         #HP steam consumption at no load(Kg/s)
LPfull = P*0.7457/DhLP  #LP steam consumption at full load(Kg/s)
LPNL = W*LPfull         ##LP steam consumption at no load(Kg/s)
HP = solve([mHP*P+cHP-HPfull,mHP*0+cHP-HPNL],[mHP,cHP])
LP = solve([mLP*P+cLP-LPfull,mLP*0+cLP-LPNL],[mLP,cLP])
xLP = (LPavail-LP[cLP])/LP[mLP]
xHP = 1000-xLP
yHP = HP[mHP]*xHP + HP[cHP]

#Results:
print 'HP steam required:',round(yHP,2),'Kg/s'

HP steam required: 0.63 Kg/s


Example 15, page no. 304¶

In [35]:
from __future__ import division

#Variable Declaration:
Cpw = 4.18 #Specific heat of water:
#From steam tables:
h2 = 2960.7                     #kJ/kg
s2 = 6.3615                     #kJ/kg
x3 = 0.863
h3 = 2404.94                    #kJ/kg
h7 = 358.59                     #kJ/kg
x10 = 0.754
h10 = 1982.91                   #kJ/kg

#Calculation:
s3 = s2
s10 = s3
m1 = (1-x3)*0.5 #Mass pf moisture in separator(in kg):
m2 = 0.5-m1 #Mass of steam entering LPT(in kg):
m3 = 0.5+m1 #Mass of water entering the hot well(in kg):
T = (m3*90+m2*40) #Temperature of water leaving hotwell(in C):
Q = 0.5*(h3-h7) #Heat transferred per kg steam generated:
Wnet = (h2-h3)*1+m2*(h3-h10) #Net work output(in kJ/kg):
Qa = h2-Cpw*T #Heat added(in kJ/kg):
n = Wnet/Qa*100 #Thermal efficiency:

#Results:
print "Temperature of water leaving hotwell: ",round(T,3),"°C"
print "Heat transferred per kg steam generated: ",round(Q,3),"kJ/kg steam"
print "Thermal efficiency: ",round(n,2),"%"

Temperature of water leaving hotwell:  68.425 °C
Heat transferred per kg steam generated:  1023.175 kJ/kg steam
Thermal efficiency:  27.59 %


Example 16, page no. 306¶

In [37]:
from __future__ import division

#Variable Declaration:
m = 35 #Steam flow rate(in kg/s):
#From steam tables:
h1 = 3530.9                     #kJ/kg
s1 = 6.9486                     #kJ/kg.K
x2 = 0.864
h2 = 2288.97                    #kJ/kg
v3 = 0.001017                   #m**3/kg
h3 = 251.40                     #kJ/kg

#Calculations:
s2 = s1
Wp = v3*(70-0.20)*10**2 #Pump work(in kJ/kg):
Wt = h1-h2 #Turbine work(in kJ/kg):
Wnet = Wt-Wp #Net work(in kJ/kg):
P = m*Wnet/10**3 #Power produced(in MW):
h4 = h3+Wp #Enthalpy at state 4(in kJ/kg):
Q = m*(h1-h4) #Total heat supplied to the boiler(in kJ/s):
n = Wnet*m/Q*100 #Thermal efficiency:

#results:
print "Net power: ",round(P,2),"MW"
print "Thermal efficiency: ",round(n,2),"%"

Net power:  43.22 MW
Thermal efficiency:  37.73 %


Example 17, page no. 307¶

In [39]:
from __future__ import division

#Variable Declaration:
P = 10 #Output(in MW):
#From steam tables:
h1 = 3625.3             #kJ/kg
s1 = 6.9029             #kJ/kg.K
h2 = 3105.08            #kJ/kg
x3 = 0.834
h3 = 2187.43            #kJ/kg
h6 = 908.79             #kJ/kg
h5 = 191.83             #kJ/kg

#Calculations:
s2 = s1
s3 = s2
h4 = h5
h7 = h6
mb = (h6-h5)/(h2-h5) #Steam bled per kg of steam passing through HP stage:
m = round(P*10**3/((h1-h2)+(1-mb)*(h2-h3)),2) #Mass of steam leaving boiler(in kg/s):
Q = m*(h1-h7) #Heat supplied to the boiler(in kJ/s):

#Results:
print "Steam bled per kg of steam passing through HP stage: ",round(mb,3),"kg"

Steam bled per kg of steam passing through HP stage:  0.246 kg


Example 18, page no. 309¶

In [41]:
from __future__ import division

#Variable Declaration:
P = 50  #Net output(in MW):
#From steam tables:
h1 = 3373.7                     #kJ/kg
s1 = 6.5966                     #kJ/kg.K
s3 = 7.7622                     #kJ/kg.K
h6 = 2930.572                   #kJ/kg
h3 = 3478.5                     #kJ/kg
T2 = 181.8                      #C
h2 = 2782.8                     #kJ/kg
T8 = 358.98                     #C
h8 = 3188.7                     #kJ/kg
x4 = 0.95
h4 = 2462.99                    #kJ/kg
h11 = 856.8                     #kJ/kg
h9 = 604.74                     #kJ/kg
h7 = 908.79                     #kJ/kg
h4a = 191.83                    #kJ/kg
v4a = 0.001010                  #m**3/kg
v9 = 0.001084                   #m**3/kg

#Calculations:
s6 = s1
s2 = s1
s8 = s3
s4 = s3
h7a = h7
h5 = h4a+v4a*(4-0.1)*10**2 #Enthalpy at state 5(in kJ/kg):
h10 = h9+v9*(100-4)*10**2 #Enthalpy at state 10(in kJ/kg):
m6 = (h11-h10)/(h6-h7) #Mass per kg of steam from boiler(in kg):
m8 = (h9-(1-m6)*h5-m6*h7a)/(h8-h5)
m6 = 0.135
m8 = 0.105
Whpt = (h1-h6)+(1-m6)*(h6-h2) #Work in turbines(in kJ/kg):
Wlpt = (1-m6)*(h3-h8)+(1-m6-m8)*(h8-h4)
Wcep = (1-m6-m8)*(h5-h4a) #Pump works(in kJ/kg)
Wfp = h10-h9
m = P*10**3/(Whpt+Wlpt-Wcep-Wfp)#Mass of steam entering first stage of turbine(in kg/s):
Q = m*(h1-h11) #Heat supplied in the boiler(in kJ/s):
n = P*10**3/Q*100 #Thermal efficiency:

#Results:
print "Mass of steam bled at 20 bar: ",round(m6,3)," kg per kg of steam entering first stage"
print "Mass of steam bled at 4 bar: ",round(m8,3)," kg per kg of steam entering first stage"
print "Mass of steam entering first stage: ",round(m,2)," kg/s"
print "Thermal efficiency: ",round(n,2),"%"

Mass of steam bled at 20 bar:  0.135  kg per kg of steam entering first stage
Mass of steam bled at 4 bar:  0.105  kg per kg of steam entering first stage
Mass of steam entering first stage:  36.7  kg/s
Thermal efficiency:  54.13 %


Example 19, page no. 312¶

In [43]:
from __future__ import division

#Variable Declaration:
nt = 0.85   #Turbine efficiency:
ng = 0.90  #Generator efficiency:
nm = 0.95  #Mechanical efficiency:
Cpw = 4.18 #Specific heat of water:
#From steam tables:
h1 = 3450.02                        #kJ/kg
s1 = 6.6923                         #kJ/kg.K
h3 = 3576.99                        #kJ/kg
s3 = 7.52411                        #kJ/kg.K
h2 = 3010                           #kJ/kg
h9 = 3175                           #kJ/kg
h4 = 2300                           #kJ/kg
h5 = 137.82                         #kJ/kg
v5 = 0.001005                       #m**3/kg
h8 = 962.11                         #kJ/kg
h12 = 1407.56                       #kJ/kg
h10 = 670.56                        #kJ/kg
v10 = 0.001101                      #m**3/kg
PO = 120                            #Plant output(MW)

#Calculations:
h2a = h1-(h1-h2)*nt #Enthalpy at state 2'(in kJ/kg):
h9a = h3-(h3-h9)*nt  #Enthalpy at state 9'(in kJ/kg):
h4a = h3-(h3-h4)*nt  #Enthalpy at state 4'(in kJ/kg):
h6 = h5+v5*(6-0.05)*10**2 #Enthalpy at state 6(in kJ/kg):
h6a = h5+(h6-h5)/ng #Enthalpy at state 6'(in kJ/kg):
h11 = h10+v10*(100-6)*10**2 #Enthalpy at state 11(in kJ/kg):
h11a = h10+(h11-h10)/ng  #Enthalpy at state 11'(in kJ/kg):
m1 = round((h11a-h12)/(h8-h2a),3)   #Mass flow rate(in kg/kg steam):
m2 = round((h10-m1*h8-(1-m1)*h6a)/(h9-h6a),3)
Whp = h1-h2a    #Work from HP turbine(in kJ/kg):
Wlp = (1-m1)*(h3-h9a)+(1-m1-m2)*(h9a-h4a)#Work from LP turbine(in kJ/kg):
Wp = (1-m1-m2)*(h6a-h5)+(h11a-h10)  #Pump work:
Wnet = Whp+Wlp-Wp #Net work(in kJ/kg):
ssc = 3600/(Wnet*ng*nm)  #Specific steam consumption(in kg/kw.h):
ssc = 3.93
no = Wnet*nm*ng/((h1-h12)+(1-m1)*(h3-h2a))*100  #Overall thermal efficiency:
m = ssc*PO*10**3 #Mass of steam required(in kg/hr):

#Results:
print "Specific steam consumption: ",round(ssc,2),"kg/kw.h"
print "Overall efficiency: ",round(no,2),"%"
print "Mass of steam held from HP turbine: ",round(m1*m,1),"kg/hr"
print "Mass of steam held from LP turbine: ",round(m2*m,1),"kg/hr"

print m1, m2

Specific steam consumption:  3.93 kg/kw.h
Overall efficiency:  36.57 %
Mass of steam held from HP turbine:  161758.8 kg/hr
Mass of steam held from LP turbine:  38671.2 kg/hr
0.343 0.082


Example 20, page no. 316¶

In [45]:
from __future__ import division

#Variable Declaration:
P = 14000 #Power required(in kW):
r = 0.75 #Efficiency ratio of turbine:
#From steam tables:
h1 = 3137                               #kJ/kg
s1 = 6.9563                             #kJ/kg.K
x2 = 0.765
h2 = 2170.38                            #kJ/kg
hf = 467.11                             #kJ/kg

#Calculations:
s2 = s1
h2a = h1-(h1-h2)*r #Enthalpy at state 2'(in kJ/kg):
m = P/(h2a-hf) #Mass of steam required(in kg/s):
P1 = m*(h1-h2a) #Power available to the generator(in kW):

#Results:
print "Power available to the generator: ",round(P1,2),"kW"

Power available to the generator:  5218.46 kW


Example 21, page no. 317¶

In [48]:
from __future__ import division

#Variable Declaration:
nt = 0.80 #Turbine efficiency:
nb = 0.80 #Boiler efficiency:
P = 9000 #Power required(in kW):
h1 = 3137 #kJ/kg #From steam tables:
s1 = 6.9563 #kJ/kg.K
s2 = s1
x2 = 0.960
h2 = 2638.34 #kJ/kg
hf = 503.71 #kJ/kg

#Calculations:
h2a = h1-(h1-h2)*nt #Enthalpy at state 2'(in kJ/kg):
ms = P/(h2a-hf) #Mass flow rate(in kg/s):
P1 = ms*(h1-h2a) #Power developed(in kW):
pt = (h1-hf)*ms #Total heat consumption in the bolier(in kW):
pa = pt/nb #Actual heat consumption(in kJ/s):

#Results:
print "Power developed: ",round(P1,2),"kW"
print "Actual heat consumption: ",round(pa,2),"kJ/s"

Power developed:  1606.88 kW
Actual heat consumption:  13258.6 kJ/s


Example 22, page no. 318¶

In [51]:

#Variable Declaration:
P = 4500 #Total power required(in kW):
Q = 15000 #Heat load(in kW):
n = 0.80 #Efficiency of turbines:
m = 10  #Steam consumption rate(in kg/s):
#From steam tables:
h1 = 3137                               #kJ/kg
s1 = 6.9563                             #kJ/kg.K
T2 = 179.18                             #C
h2 = 2813.41                            #kJ/kg
hf = 640.23                             #kJ/kg
#For case 1:
T2a = 213.34                            #C
s2a = 7.125                             #kJ/kg.K
x3 = 0.853
h3 = 2221.11                            #kJ/kg
#For case 2:
h2a = 2878.13                           #kJ/kg
T3aa = 210.04                           #C
s3aa = 7.138                            #kJ/kg.K
x4 = 0.855
h4 = 2225.92                            #kJ/kg

#Calculations:
s3 = s2a
h3aa = h2a
s4 = s3aa
h2a = h1-(h1-h2)*n #Enthalpy at state 2'(in kJ/kg):
q = h2a-hf #Heat available for process heating(in kJ/kg):
msh = Q/q #Mass flow rate(in kg/s):
h3a = h2-(h2a-h3)*n #Enthalpy at state 3'(in kJ/kg):
mshp = (P+msh*(h2a-h3a))/((h1-h2a)+(h2a-h3a)) #Mass of steam produced:
#For case 2:
mshpn = 10
mshn = 6.7
Pn = mshpn*(h1-h2a) #Power produced by HP turbine(in kW):
M3aa = mshpn-mshn
h4a = h3aa-(h3aa-h4)*n #Enthalpy at state 4'(in kJ/kg):
Pn1 = M3aa*(h3aa-h4a) #Power produced by LP turbine(in kW):
Pt = Pn+Pn1 #Total power produced(in kW):

#Results:
print "Total power produced: ",round(Pt,2),"kW"

Total power produced:  4310.55 kW


Example 23, page no. 322¶

In [54]:
from __future__ import division

#Variable Declaration:
na = 0.975 #Alternator efficiency:
nt = 0.80 #Turbine efficiency:
L = 50 #Turbine's losses(in kW):
p = 8 #Electric power developed(in mW):
m = 8 #Condenser discharge(in kg/s):
#From steam tables:
h1 = 3137                               #kJ/kg
s1 = 6.9563                             #kJ/kg.K
s1a = 7                                 #kJ/kg.K
h2 = 2830                               #kJ/kg
h4 = 2210                               #kJ/kg
hf = 376.92                             #kJ/kg

#Calculations:
h1a = h1
s2 = s1a
h2a = h1a-(h1a-h2)*nt #Enthalpy at state 2'(in kJ/kg):
h3 = h2a
h4a = h3-(h3-h4)*nt #Enthalpy at state 4'(in kJ/kg):
P = m/na #Power available to the alternator(in MW):
Pt = P*10**3+L #Total power produced(in kW):
plp = m*(h3-h4) #Power produced by LP turbine(in kW):
php = Pt-plp #Power produced by LP turbine(in kW):
m1 = round(php/(h1a-h2a),2) #Mass flow rate through HP turbine(in kg/s):
ph = (m1-m)*(h2-hf) #Heat available for process heating(in kW):

#Results:
print "Heat available for process heating: ",round(ph,2),"kW"

Heat available for process heating:  8389.53 kW


Example 24, page no. 323¶

In [56]:
from __future__ import division

#Variable Declaration:
nt = 0.80 #Turbine efficiency:
nm = 0.90 #Mechanical efficiency:
p = 720 #Power delivered by turbine(in kW):
#From steam tables:
h1 = 3045.8                             #kJ/kg
s1 = 7.0317                             #kJ/kg.K
x4 = 0.841
h4 = 2192.24                            #kJ/kg.K
h2 = 2706.7                             #kJ/kg
s2 = 7.1271                             #kJ/kg.K
x3 = 0.854
h3 = 2223.51                            #kJ/kg

#Calculation:
s4 = s1
s3 = s2
h4a = h1-(h1-h4)*nt #Enthalpy at state 4'(in kJ/kg):
h3a = h2-(h2-h3)*nt #Enthalpy at state 3'(in kJ/kg):
P = p/nm #Power developed in the turbine(in kW):
m1 = 3600/(h1-h4a) #HP steam consumption(in kg/kW.h):
m2 = 3600/(h2-h3a) #LP steam consumption(in kg/kW.h):

#Results:
print "HP steam consumption: ",round(m1,2),"kg/kW.h"
print "LP steam consumption: ",round(m2,2),"kg/kW.h"

HP steam consumption:  5.27 kg/kW.h
LP steam consumption:  9.31 kg/kW.h


Example 25, page no. 325¶

In [60]:
from __future__ import division

#Variable Declaration:
mhp = 2 #Mass flow rate(in kg/s):
mlp = 1.5
n = 0.90 #Expansion efficiency:
P = 3000 #Power developed by the turbine(in kW):
#From steam tables:
h1 = 3034.8                     #kJ/kg
s1 = 6.8844                     #kJ/kg.K
x3 = 0.9566
h3 = 2611.04                    #kJ/kg
h2 = 2706.7                     #kJ/kg
xout = 0.8535
hout = 2222.31                  #kJ/kg
h4 = 2676.25                    #kJ/kg
h5 = 2290                       #kJ/kg

#Calculations:
s3 = s1
hin = h2
h3a = h1-(h1-h3)*n #Enthalpy at state 3'(in kJ/kg):
houta = hin-(hin-hout)*n #Enthalpy of steam going out(in kJ/kg):
ms = P/(hin-hout) #Mass flow rate of steam(in kg/s):
h5a = h4-(h4-h5)*n #Enthalpy at state 5'(in kJ/kg):
p = mhp*(h1-h3a)+(mhp+mlp)*(h4-h5a)#Power output from mixed pressure turbine(in kW):

#Results:
print "Power: ",round(p,2),"KW"

Power:  1979.46 KW