Steam Generation

Example 5.1,Page 296

In [22]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
x=0.98
vg=26.80
vf=0.01672

#calculations
vx=x*vg+(1-x)*vf #specific wet volume

#results
print "Specific volume of wet steam in cu ft per lb",round(vx,3)

Specific volume of wet steam in cu ft per lb 26.264

Example 5.2,Page 298

In [21]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
hf=167.99 #Btu/lb
hg=4.5 #Btu/lb

#calculations
hc=hf+hg

#results
print "Enthalpy of water in Btu/lb",round(hc,3)

Enthalpy of water in Btu/lb 172.49

Example 5.3,Page 300

In [23]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
x=0.97
hg=1187.2 #Btu/lb
hf=298.40 #Btu/lb
hfg=888.8 #Btu/lb

#calculations
hx1=x*hg+(1-x)*hf
hx2=hf+x*hfg
hx3=hg-(1-x)*hfg

#results
print " In case 1, enthalpy in Btu/lb",round(hx1,3)
print " In case 2, enthalpy in Btu/lb",round(hx2,3)
print " In case 3, enthalpy in Btu/lb",round(hx3,3)

 In case 1, enthalpy in Btu/lb 1160.536
 In case 2, enthalpy in Btu/lb 1160.536
 In case 3, enthalpy in Btu/lb 1160.536

Example 5.4,Page 302

In [7]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
h1=1172.0 #Btu/lb
hf1=355.36 #Btu/lb
hfg1=843.0 #Btu/lb

#calculations
h2=h1
x1= (h2-hf1)/hfg1

#results
print "Quality of steam in percent",round(x1*100,3)

96.873 Quality of steam in percent

Example 5.7,Page 306

In [26]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
P=200 #psia
T=260 #F

#calculations
#"From mollier chart"
hx=1174 #Btu/lb
x1=2.8 #percent
y1=100-x1 #percent

#results
print "Quality in percent",round(y1,3)

Quality in percent 97.2

Example 5.8,Page 306

In [27]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
P=200 #psia
T=500 #F

#calculations
#"From mollier chart"
hi=1269 #Btu/lb
hf=1063 #Btu/lb
dh=hi-hf
y1=91

#results
print "Quality in percent",round(y1,3)
print  " Change in enthalpy in Btu/lb",round(dh,3)

Quality in percent 91.0
 Change in enthalpy in Btu/lb 206.0

Example 5.9,Page 307

In [13]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
P=200 #psia
Ts=260 #F
Tf=220 #F
m=10000 #lb
Pc=20 #psia

#calculations
#"From mollier charts"
hf=188.0 #Btu/lb
h2=1172.0 #Btu/lb
Q=m*(h2-hf)

#results
print "Heat absorption in Btu/hr",round(Q,3)

9840000.0 Heat absorption in Btu/hr

Example 5.10,Page 307

In [28]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
m=150000.0 #lb
P1=1000.0 #psia
Ts=900.0 #F
Tf=200.0 #F

#calculations
#"From mollier charts"
h2=1448.2 #Btu/lb
hf=167.99 #Btu/lb
correc=2.2 #Btu/lb
hc=hf+correc
Q=m*(h2-hc)

#results
print "Heat absorption in Btu/hr",round(Q,3)
print"The answer is a bit different due to rounding off error in textbook"

Heat absorption in Btu/hr 191701500.0
The answer is a bit different due to rounding off error in textbook

Example 5.11,Page 308

In [29]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
m=150000.0 #lb
P1=1000.0 #psia
Ts=900.0 #F
Tf=200.0 #F

#calculations
#"From mollier charts"
h2=1448.2 #Btu/lb
hf=167.99 #Btu/lb
correc=2.2 #Btu/lb
hc=hf+correc
Q=m*(h2-hc)
output=Q/1000

#results
print "Output of the steam generating unit  kB/hr",round(output,3)

Output of the steam generating unit  kB/hr 191701.5

Example 5.12,Page 308

In [30]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
m=150000 #lb
P1=1000 #psia
Ts=900 #F
Tf=200 #F
m2=21000 #lb
HV=12000 #Btu/lb

#calculations
#"From mollier charts"
h2=1448.2 #Btu/lb
hf=167.99 #Btu/lb
correc=2.2 #Btu/lb
hc=hf+correc
Q=m*(h2-hc)
output=Q
inpu=m2*HV
eta=output/inpu

#results
print "Efficiency of the steam generating unit in percent",round(eta*100,3)

Efficiency of the steam generating unit in percent 76.072

Example 5.13,Page 309

In [31]:
# Initialization of Variable
from math import pi
from math import atan
from numpy import *
hv=11780 #Btu/lb
steam=55000 #lb/hr
coal=6480 #lb
x1=0.66 # %Carbon
x2=0.044 #% Hydrogen
x3=0.079 #% Oxygen
x4=0.015 #% Nitrogen
x5=0.11 # % Sulphur
z1=14.5 # % CO2
z2=0.2 # CO
z3=4.4 # O2
z4=80.9 # N2
xash=0.076 #% ash
xmois=0.115 # % moisture
yc=0.21 # % Carbon in refuse
refuse=622 #lb/hr
cp=0.24 #coeff of heat
tg=400 #F
ta=70 #F
Qco=10160 #Btu/lb
Qc=14600 #Btu/lb

#calculations
#"From steam tables"
hf=269.6 #Btu/lbm
hfg=1.5 #Btu/lbm
h1=hf+hfg #Btu/lbm
h2=1196.5
Qb=h2-h1
h3=1407.7 #Btu/lbm
Qs=h3-h2
h4=h3-h1
out=steam*h4/1000
eff=steam*h4/(coal*hv)
#Energy balance
Ci=coal*x1
Cr=refuse*yc
Cb=(Ci-Cr)/coal
lbt= z1*44+z2*28+z3*32+z4*28
lbC=z1*12+z2*12
dry=lbt/lbC *Cb
loss1=dry*cp*(tg-ta)
loss2=z2*12/(lbC) *Cb*Qco
loss3=Cr*Qc/coal
loss4=xmois*(1089+0.46*tg-ta)
loss5=x2*9*(1089+0.46*tg-ta)
loss6=steam*h4/coal

#results
print "Heat absorbed in the boiler in Btu per lb of steam generated",round(Qb,3)
print " Heat absorbed in the superheater in Btu/lb of steam",round(Qs,3)
print  " Heat absorbed in steam generating in Btu/lb of steam generated",round(h4,3)
print " Output of steam generating unit in kB",round(out,3)
print " Efficiency of steam generating unit in percent",round(eff*100,3)
print  " Carbon burned to CO and CO2 in lb of C per lb of fuel",round(Cb,3)
print " Dry products of combustion in lb per lb of fuel",round(dry,3)
print " Loss due to sensible heat in dry gaseous products of combustion in Btu/lb of fuel",round(loss1,3)
print " Loss due to CO in dry products of combustion in Btu/lb of fuel",round(loss2,3)
print  " Loss due to C in refuse in Btu/lb of fuel",round(loss3,3)
print " Loss due to evaporating moisture in fuel in Btu/lb of fuel",round(loss4,3)
print " Loss due to water vapor formed from H in Btu/lb of fuel",round(loss5,3)
print  " Energy absorbed in generating steam in Btu/lb of fuel",round(loss6,3)
print "The answers are a bit different due to rounding off error in the textbook"

Heat absorbed in the boiler in Btu per lb of steam generated 925.4
 Heat absorbed in the superheater in Btu/lb of steam 211.2
 Heat absorbed in steam generating in Btu/lb of steam generated 1136.6
 Output of steam generating unit in kB 62513.0
 Efficiency of steam generating unit in percent 81.894
 Carbon burned to CO and CO2 in lb of C per lb of fuel 0.64
 Dry products of combustion in lb per lb of fuel 11.062
 Loss due to sensible heat in dry gaseous products of combustion in Btu/lb of fuel 876.078
 Loss due to CO in dry products of combustion in Btu/lb of fuel 88.446
 Loss due to C in refuse in Btu/lb of fuel 294.298
 Loss due to evaporating moisture in fuel in Btu/lb of fuel 138.345
 Loss due to water vapor formed from H in Btu/lb of fuel 476.388
 Energy absorbed in generating steam in Btu/lb of fuel 9647.068
The answers are a bit different due to rounding off error in the textbook