{
"metadata": {
"name": "",
"signature": "sha256:6a2922d727738ae70604bae46fb35f03608e71a4b1a12c93dd485fb1323281a2"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"Chapter 11: Boilers and Boiler Calculations"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 1, page no. 481"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"H = 30 #Height of chimney(in m):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"m = 20 #Mass per kg of fuel required for complete combustion(in kg):\n",
"hw = 12 #Height in the water column(in mm):\n",
"\n",
"#Calculations:\n",
"Tg = (Ta*353*H)/(353*H-hw*Ta)*(m)/(m+1)#Temperature of burnt gases(in K):\n",
"\n",
"#Results:\n",
"print \"Temperature of the burnt gases: \",round(Tg,2),\"K\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Temperature of the burnt gases: 432.86 K\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 2, page no. 482"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"m = 18 #Mass per kg of fuel required for complete combustion(in kg):\n",
"hw = 20 #Height in the water column(in mm):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"Tg = 300+273 #Temperature of burnt gases(in K):\n",
"\n",
"#Calculations:\n",
"H = hw/(353*(1/Ta-(m+1)/(m*Tg)))#Height of chimney(in m):\n",
"\n",
"#Results:\n",
"print \"Height of chimney: \",round(H,2),\"m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Height of chimney: 37.99 m\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 3, page no. 482"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"H = 20 #Height of chimney(in m):\n",
"Tg = 380+273 #Temperature of burnt gases(in K):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"\n",
"#Calculations:\n",
"m = 2*Ta/(Tg-2*Ta) #Air supplied(in kg air per fuel):\n",
"\n",
"#Results:\n",
"print \"Air supplied:\",round(m,2),\"kg/kg of fuel\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Air supplied: 11.32 kg/kg of fuel\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 4, page no. 482"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"H = 60 #Height of chimney(in m):\n",
"Ta = 17+273 #Ambient air temperature(in K):\n",
"Tg = 300+273 #Temperature of burnt gases(in K):\n",
"Tga = 150+273 #Temperature of the artificial burnt gases(in K):\n",
"m = 19 #Mass per kg of fuel required for complete combustion(in kg):\n",
"Cpg = 1.0032 #Specific heat of hot gases(in kJ/kg.K):\n",
"c = 32604 #Calorific value of burnt fuel(in kJ/kg):\n",
"\n",
"#Calculations:\n",
"hw = 353*H*(1/Ta-(m+1)/(m*Tg)) #Draught (in mm of water column):\n",
"n = 9.81*H*(m/(m+1)*Tg/Ta-1)/(Cpg*(Tg-Tga)*10**3)*100 #Chimney efficiency:\n",
"Q = (m+1)*Cpg*(Tg-Tga) #Extra heat carried away by flue gases(in kJ):\n",
"\n",
"#Results:\n",
"print \"Draught: \",round(hw,2),\" mm of water\"\n",
"print \"Chimney efficiency\",round(n,4),\"%\"\n",
"print \"Extra heat carried away by flue gases per kg of fuel burnt\",round(Q,1),\" kJ\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Draught: 34.13 mm of water\n",
"Chimney efficiency 0.3431 %\n",
"Extra heat carried away by flue gases per kg of fuel burnt 3009.6 kJ\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 5, page no. 483"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"H = 80 #Height of chimney(in m):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"m = 20 #Mass per kg of fuel required for complete combustion(in kg):\n",
"Tga = 110+273 #Temperature of the artificial burnt gases(in K):\n",
"Cpg = 1.0032 #Specific heat of hot gases(in kJ/kg.K):\n",
"\n",
"#Calculations:\n",
"Tg = Ta*2*(m+1)/m #Temperature of burnt gases(in K):\n",
"hw = 353*H*(1/Ta-(m+1)/(m*Tg)) #Draught in water column(in mm):\n",
"n = 9.81*H*(m/(m+1)*Tg/Ta-1)/(Cpg*(Tg-Tga)*10**3)*100 #Chimney efficiency:\n",
"\n",
"#Results:\n",
"print \"Hot gas temperature in chimney: \",round(Tg),\"K\"\n",
"print \"Natural draught: \",round(hw,2),\"mm of water\"\n",
"print \"Chimney efficiency: \",round(n,4),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Hot gas temperature in chimney: 630.0 K\n",
"Natural draught: 47.07 mm of water\n",
"Chimney efficiency: 0.3167 %\n"
]
}
],
"prompt_number": 12
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 6, page no. 484"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
" \n",
"from math import sqrt,pi\n",
"\n",
"#Variable Declaration: \n",
"R = 2.5*10**3 #Rate at which coal is burnt(in kg/hr):\n",
"m = 20 #Mass per kg of fuel required for complete combustion(in kg):\n",
"Tg = 327+273 #Temperature of burnt gases(in K):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"h = 7+6+3+2 #Pressure head(in mm):\n",
"na = 0.90 #Ratio of actual natural draught to theoretical draught:\n",
"g = 9.81 #Acceleration due to gravity(in m/s**2):\n",
"\n",
"#Calculations:\n",
"hw = h/na #Actual natural draught(in mm of water):\n",
"H = hw/(353*(1/Ta-(m+1)/(m*Tg))) #Height of chimney(in m):\n",
"dg = 353/Tg*(m+1)/m #Density of hot gases(in kg/m**3):\n",
"hg = H*((m+1)/m*Tg/Ta-1) #Height of hot gases column(in m):\n",
"Mg = R*hw/3600 #Mass flow rate of hot gases(in kg/s):\n",
"C = sqrt(2*g*hg) #Velocity of got gases(in m/s):\n",
"D = sqrt((4*Mg)/(pi*C*dg)) #Diameter of chimney(in m):\n",
"\n",
"#Results:\n",
"print \"Height of chimney:\",round(H,2),\"m\"\n",
"print \"Diameter of chimney:\",round(D,2),\"m\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Height of chimney: 35.78 m\n",
"Diameter of chimney: 1.01 m\n"
]
}
],
"prompt_number": 14
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 7, page no. 485"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
" \n",
"#Variable Declaration: \n",
"hw = 50 #Draught in water column(in mm):\n",
"T = 300+273 #Temperature of burnt gases(in K):\n",
"m = 19 #Mass per kg of fuel required for complete combustion(in kg):\n",
"T1 = 27+273 #Ambient air temperature(in K):\n",
"T0 = 273 #Zero temperature(in K):\n",
"n = 0.90 #Mechanical efficiency:\n",
"d = 1.293 #Density of hot gases(in kg/m**3):\n",
"\n",
"#Calculations:\n",
"M = 2000/3600 #Rate at which coal is burnt(in kg/s):\n",
"P = hw*9.81 #Pressure applied by the draught water(in N/m**2):\n",
"PFD = P*m*M*T1/(d*T0*n*1000) #Power required in FD fan(kW):\n",
"P1D = P*m*M*T/(d*T0*n*1000) #Power required in 1D fan(kW):\n",
"\n",
"#Results:\n",
"print \"Power for FD fan:\",round(PFD,2),\"kW\"\n",
"print \"Power for 1D fan:\",round(P1D,2),\"kW\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Power for FD fan: 4.89 kW\n",
"Power for 1D fan: 9.34 kW\n"
]
}
],
"prompt_number": 16
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 8, page no. 486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"Cpg = 1.0032 #Specific heat of hot gases(in kJ/kg.K):\n",
"Tg = 177+273 #Temperature of burnt gases(in K):\n",
"Ta = 27+273 #Ambient air temperature(in K):\n",
"Tn = 327+273 #Natural draught temperature(in K):\n",
"mn = 25 #Mass per kg of fuel required for natural draught(in kg):\n",
"ma = 20 #Mass per kg of fuel required for artificial draught(in kg):\n",
"r = Tg/Ta #Ratio of brake power for induced draught to forced draught:\n",
"\n",
"#Calculations:\n",
"Qgad = (ma+1)*Cpg*(Tg-Ta) #Heat carried by hot flue gases in artificial draught(in per kg of fuel burnt):\n",
"Qgnd = (mn+1)*Cpg*(Tn-Ta) #Heat carried by hot flue gases in natural draught(in per kg of fuel burnt):\n",
"rh = Qgad/Qgnd #Ratio of heat carried away:\n",
"\n",
"#Results:\n",
"print \"Ratio of power required: \",round(r,1)\n",
"print \"Ratio of heat carried away: \",round(rh,3)"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Ratio of power required: 1.5\n",
"Ratio of heat carried away: 0.404\n"
]
}
],
"prompt_number": 18
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 9, page no. 486"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"T = 27+273 #Feed water supply temperature(in K):\n",
"P = 10 #Mean steam generation pressure(in bar):\n",
"x = 0.95 #Dryness fravtion of steam generated:\n",
"Q = 2500 #Feed water supplied(in kg/hr):\n",
"Q1 = 275 #Coal burnt(in kg/hr):\n",
"d = 300 #Difference in mass of water after trial:\n",
"hf = 762.81 #kJ/kg #From steam tables:\n",
"hg = 2778.1 #kJ/kg\n",
"hfg = 2015.29 #kJ/kg\n",
"\n",
"#Calculations:\n",
"h = hf+x*hfg #Enthalpy of steam generated(in kJ/kg):\n",
"mw = Q+d #Mass of water evaporator per hour(in kg/hr):\n",
"Ae = mw/Q1 #Actual evaporation(in per kg of coal):\n",
"Ee = Ae*h/2257 #Equivalent evaporation(in kg per kg of coal):\n",
"\n",
"#Results:\n",
"print \"Actual evaporation: \",round(Ae,2),\" kg per kg of coal\"\n",
"print \"Equivalent evaporation: \",round(Ee,2),\"kg per kg of coal\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Actual evaporation: 10.18 kg per kg of coal\n",
"Equivalent evaporation: 12.08 kg per kg of coal\n"
]
}
],
"prompt_number": 22
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 10, page no. 487"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
" \n",
"#Variable Declaration: \n",
"p = 10 #Average pressure of the steam(in bar):\n",
"Ww = 15 #Weight of water consumed(in ton):\n",
"Wc = 1.5 #Weight of coal produced(in ton):\n",
"n = 1-0.03-0.04 #Percentage coal that caan be burnt:\n",
"nm = 0.03 #Composition of moisture in coal:\n",
"Tf = 35 #Temperature of feed water(in C):\n",
"hg = 2778.1 #From steam tables(kJ/kg) \n",
"\n",
"#Calculations:\n",
"h = hg-4.18*Tf #Enthalpy of steam generated(in kJ/kg):\n",
"m = Ww/Wc #Steam generated per kg of coal(in kg):\n",
"nb = m*h/(30.1*10**3)*100 #Boiler efficiency:\n",
"Ee = m*h/(2257*(1-nm)) #Equivalent evaporation per kg of dry coal(in kg:\n",
"Eea = Ee*(1-nm)/n #Equivalent evaporation per kg of combustible present in coal(in kg):\n",
"\n",
"#Results:\n",
"print \"Boiler efficiency: \",round(nb,2),\"%\"\n",
"print \"Equivalent evaporation per kg of dry coal: \",round(Ee,2),\"kg\"\n",
"print \"Equivalent evaporation per kg of combustible present in coal: \",round(Eea,2),\"kg\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Boiler efficiency: 87.44 %\n",
"Equivalent evaporation per kg of dry coal: 12.02 kg\n",
"Equivalent evaporation per kg of combustible present in coal: 12.54 kg\n"
]
}
],
"prompt_number": 24
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 11, page no. 488"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"t = 24 #Time of trial(in hrs):\n",
"p = 16 #Pressure at which steam is generated(in bar):\n",
"c = 10000 #Coal consumed(in kg):\n",
"r = 2500 #Rate of steam generation(in kg/hr):\n",
"Tf = 27 #Feed water temperature(in C):\n",
"hsa = 3000 #Total heating surface area(in m**2):\n",
"ga = 4 #Total grate area(in m**2):\n",
"C = 28000 #Calorific value of coal(in kJ/kg):\n",
"hg = 2794 #From steam tables(kJ/kg)\n",
"L = 2257 #Latent heat at 100 C:\n",
"\n",
"#Calculations:\n",
"m = c/t #Coal burnt per hour(in kg/hr):\n",
"mg = m/ga #Coal burnt per m**2 of grate per hour:\n",
"r1 = r/m #Rate of steam generated per kg of coal(in kg steam/kg coal):\n",
"Q = r1*(hg-4.18*Tf) #Heat added to steam per kg of coal(in kJ):\n",
"Ee = Q/L #Equivalent evaporation from and at 100 C per kg of coal(in kg):\n",
"Eepm = Ee*m/hsa #Equivalent evaporation from and at 100 C per m**2 of total surface per hour(in kg):\n",
"n = Ee*L/C*100 #Boiler efficiency:\n",
"\n",
"#Results:\n",
"print \"Mass of coal burnt per m**2 of grate per hour: \",round(mg,2),\"kg\"\n",
"print \"Equivalent evaporation from and at 100 C per kg of coal: \",round(Ee,2),\"kg\"\n",
"print \"Equivalent evaporation from and at 100 C per m**2 of total surface per hour: \",round(Eepm,2),\"kg\"\n",
"print \"Boiler efficiency: \",round(n,2),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Mass of coal burnt per m**2 of grate per hour: 104.17 kg\n",
"Equivalent evaporation from and at 100 C per kg of coal: 7.13 kg\n",
"Equivalent evaporation from and at 100 C per m**2 of total surface per hour: 0.99 kg\n",
"Boiler efficiency: 57.45 %\n"
]
}
],
"prompt_number": 26
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 12, page no. 489"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"p = 30 #Pressure at which steam is generated(in bar):\n",
"Ts = 300 #Temperature of steam(in C):\n",
"r = 11 #Rate at which feed water enters(in kg/s):\n",
"T1 = 100 #Temperature at which feed water enters the economiser(in C):\n",
"m = 5000 #Mass of fuel used(in kg):\n",
"C = 35000 #Calorific value of fuel(in kJ/kg.K):\n",
"T = 27 #Temperature of feed water(in C):\n",
"hg = 2993.5 #From steam tables:\n",
"L = 2257 #Latent heat at 100 C:\n",
"\n",
"#Calculations:\n",
"ms = r*3600/m #Mass of steam genrated per kg of fuel(in kg/kg fuel):\n",
"Q = hg-4.18*T #Heat added per kg of fuel(in kJ):\n",
"Ee = ms*Q/L #Equivalent evaporation from and at 100 C per kg of coal(in kg):\n",
"n = Ee*L/C*100 #Boiler efficiency:\n",
"Q1 = ms*4.18*(T1-T) #Heat utilised in economiser per kg of fuel(in kJ):\n",
"P = Q1/C*100 #Percentage of energy utilised in economiser:\n",
"\n",
"#Results:\n",
"print \"Equivalent evaporation per kg of fuel: \",round(Ee,2),\"kg\"\n",
"print \"Boiler efficiency: \",round(n,2),\"%\"\n",
"print \"Percentage of energy utilised in economiser: \",round(P,1),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Equivalent evaporation per kg of fuel: 10.11 kg\n",
"Boiler efficiency: 65.18 %\n",
"Percentage of energy utilised in economiser: 6.9 %\n"
]
}
],
"prompt_number": 28
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 13, page no. 489"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"m = 8 #Mass of steam genrated per kg of fuel:\n",
"Ts = 400 #Temperature of steam(in C):\n",
"p = 30 #Pressure of feed water(in bar):\n",
"T = 40 #Temperature of feed water(in C):\n",
"T1 = 150 #Temperature at which feed water leaves the economiser(in C):\n",
"x = 0.98 #Dryness fraction:\n",
"C = 29000 #Calorific value(in kJ/kg.K):\n",
"h = 3230.9 #Enthalpy of steam generated(in kJ/kg): #From steam tables:\n",
"hf = 1008.42 #kJ/kg\n",
"hfg = 1795.78 #kJ/kg\n",
"\n",
"#Calculations:\n",
"Q = h-4.18*T #Heat to be added(in kJ):\n",
"n = m*Q/C*100 #Boiler efficiency:\n",
"Q1 = 4.18*(T1-T) #Heat added in economiser per kg of steam generated(in kJ/kg):\n",
"r1 = Q1/Q*100 #Percentage fraction of heat in economiser:\n",
"Q2 = (hf+x*hfg)-4.18*T1 #Heat added in evaporator per kg of steam generated(in kJ/kg):\n",
"r2 = Q2/Q*100 #Percentage fraction of heat in economiser:\n",
"Q3 = Q-Q1-Q2 #Heat added in super heater per kg of steam generated by difference(in kJ/kg):\n",
"r3 = Q3/Q*100 #Percentage fraction of heat in economiser:\n",
"\n",
"#Results:\n",
"print \"Boiler efficiency: \",round(n,2),\"%\"\n",
"print \"Percentage fraction of heat in economiser: \",round(r1,2),\"%\"\n",
"print \"Percentage fraction of heat in evaporator: \",round(r2,2),\"%\"\n",
"print \"Percentage fraction of heat in superheater: \",round(r3,2),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Boiler efficiency: 84.52 %\n",
"Percentage fraction of heat in economiser: 15.01 %\n",
"Percentage fraction of heat in evaporator: 69.89 %\n",
"Percentage fraction of heat in superheater: 15.1 %\n"
]
}
],
"prompt_number": 30
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 14, page no. 490"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"T1 = 20 #Temperature at which feed water enters and leaves the economiser(in C):\n",
"T2 = 125\n",
"r = 3 #Rate at which feed water leaves the economiser(in kg/s):\n",
"T3 = 425 #Temperature of flue gases at inlet and outlet of economiser(in C):\n",
"T4 = 300\n",
"r1 = 18 #Rate at which coal is supplied(in kg/min):\n",
"nc = 0.80 #% of C in coal:\n",
"Cpg = 1.05 #Specific heat of flue gases(in kJ/kg.K):\n",
"Ta = 15 #Atmospheric temperature(in C):\n",
"m1 = 23.65 #Mass of dry flue gases at inlet and exit of economiser(in kg):\t\t\t\t#From table:\n",
"m2 = 24.78\n",
"\n",
"#Calculations:\n",
"A = m2-m1 #Air leakage in economiser per kg of coal:\n",
"Q1 = m1*Cpg*T3+A*Cpg*Ta #Heat entering economiser with flue gases and leakage(in kJ):\n",
"Q2 = m2*Cpg*T4 #Heat entering economiser with flue gases and leakage(in kJ):\n",
"Q = Q1-Q2 #Heat lost in economiser per kg of coal(in kJ):\n",
"Q3 = (r*60/r1)*4.18*(T2-T1)\t#Heat picked up by feed water in economiser per kg of coal(in kJ):\n",
"\n",
"#Results:\n",
"print \"Heat released by the flue gases: \",round(Q,2),\"kJ per kg of coal\"\n",
"print \"Air leakage: \",round(A,2),\"kg per kg of coal\"\n",
"print \"Heat gained by feed water: \",round(Q3),\"kJ per kg of coal\"\n",
"print \"___Please check there is a calculation mistake in book in calculating Q3____\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Heat released by the flue gases: 2765.91 kJ per kg of coal\n",
"Air leakage: 1.13 kg per kg of coal\n",
"Heat gained by feed water: 4389.0 kJ per kg of coal\n",
"___Please check there is a calculation mistake in book in calculating Q3____\n"
]
}
],
"prompt_number": 32
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 15, page no. 492"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"CpKg = 0.84 #Carbon present per kg:\n",
"CpKgDf = 0.0495 #Carbon present per kgof dry fluegas:\n",
"sg = 8 #Steam generated (kg per kg of coal):\n",
"mh = 0.04*9 #H2O produced during the combustion(kg per kg of coal):\n",
"ash = 0.05 #Ash produced duing cumbustion(kg per kg of coal):\n",
"M = 0.015 #Moisture in coal burnt per kg of coal:\n",
"h = 3213.6 #Enthalpy of heat generated at 40 bar 400\u00b0C (KJ/Kg):\n",
"C = 4.18 #Heat capacity of water (KJ/Kg.K):\n",
"Ti = 27 #Feed water temperature at inlet to economiser (\u00b0C):\n",
"Te = 137 #Feed water temperature at exit of economiser(\u00b0C):\n",
"Tfe = 300 #Flue gas temperature entering air heater(\u00b0C):\n",
"Tae = 120 #Temperature of air entering boiler furnace(\u00b0C):\n",
"Tatm = 15 #Atmospheric air temperature(\u00b0C):\n",
"Hs = 32600 #Heat supplied by the fuel(KJ/Kg coal):\n",
"cp = 1.0032 #Heat capacity of air and dry gas (KJ/Kg.K):\n",
"sp = 2.0064 #Specific pressure of vapour(KJ/Kg.K):\n",
"\n",
"#Calculations:\n",
"md = CpKg/CpKgDf #Mass of dry flue gas per kg of coal: #Specific pressure of vapour = 2.0064 kJ/kg K\t\t\t\t#Partial pressure of vapour in flue gas = 0.075 bar\t\t\t\t#For air and dry flue gas, cp = 1.0032 kJ/kg K\t\t\t\t#Calorific value of coal = 32600 kJ/kg\t\t\t\t#Datum temperature = 15C\t\t\t\t#Dry flue gas composition by volume = 12.5% CO2, 7.5% O2, 80% N2\t\t\t\t#Dry coal composition by mass = 84% C, 4% H2, 7% O2 and remainder ash\t\t\t\t#Temperature of air entering boiler furnace = 120C\t\t\t\t#Flue gas temperature leaving air heater and entering chimney = 150C\t\t\t\t#Flue gas temperature entering air heater = 300C\t\t\t\t#Moisture in coal burnt = 1.5%\t\t\t\t#Feed water temperature at exit of economiser = 137C\t\t\t\t#Feed water temperature at inlet to economiser = 27C\t\t\t\t#Steam generated per kg of coal = 8 kg\t\t\t\t#Steam generation: 40 bar, 400C\t\t\t\t#Atmospheric air temperature: 15C\n",
"ma = md-(1-ash-mh) #Amount of air supplied for combustion of one kg of dry coal(in kg):\n",
"m = M/(1-M) #Moisture per kg of dry coal(in kg):\n",
"mt = round(mh+m,4)#Total moisture per kg of coal(in kg):\n",
"sgd = sg/(1-M) #Steam generated per kg of dry coal(in kg steam):\n",
"H = sgd*(h-C*Ti) #Heat utilized by steam per kg of coal(KJ):\n",
"n = H/Hs*100 #Boiler efficiency:\n",
"Hu = ma*cp*(Tae-Tatm) #Heat utilized by air(KJ/Kg of coal)\n",
"Ha = (md*cp+mt*sp)*(Tfe-Te) #Heat available in air heater(KJ/Kg of coal):\n",
"na = Hu/Ha*100 #Efficiency of heat exchange in air heater:\n",
"\n",
"#Results:\n",
"print \"Boiler efficiency: \",round(n,2),\"%\"\n",
"print \"Efficiency of heat exchange in air heater: \",round(na,2),\"%\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Boiler efficiency: 77.25 %\n",
"Efficiency of heat exchange in air heater: 59.54 %\n"
]
}
],
"prompt_number": 34
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 17, page no. 496"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"p = 20 #Pressure at which steam is generated(in bar):\n",
"Ts = 300 #Temperature at which steam is generated(in C):\n",
"T1 = 50 #Temperature of feed water supplied to the boiler(in C):\n",
"C = 30000 #Calorific value of fuel(in kJ/kg):\n",
"r = 600 #Rate at which coal is used(in kg/hr):\n",
"r1 = 5000 #Rate at which steam is generated(in kg/hr):\n",
"T = 100 #Temperature of the boiler unit(in C):\n",
"L = 2257 #Latent heat(in kJ/kg.K):\n",
"\n",
"#Calculations:\n",
"ms = r1/r #Steam generation per unit coal burnt per hour:\n",
"hfi = 3023.5 #Final enthalpy of the steam(in kJ/kg):\n",
"hfw = 209.33 #Enthalpy of feed water(in kJ/kg):\n",
"no = ms*(hfi-hfw)/C*100 #Overall efficiency of boiler:\n",
"Ee = ms*(hfi-hfw)/L #Equivalent evaporation of boiler unit(in kg steam per kg of coal):\n",
"Eea = Ee*r #Equivalent evaporation of boiler unit at 100 C(in kg/hr):\n",
"hfw1 = 313.93 #After fitting economiser the enthalp of feed water(in kJ/kg):\n",
"nom = no+5 #Modified overall efficiency of boiler unit:\n",
"mc = (hfi-hfw1)*r1*100/(C*nom) #Coal consumption(in kg/hr):\n",
"s = r-mc #Saving of coal(in kg/hr):\n",
"\n",
"#Results:\n",
"print \"Saving of coal: \",round(s,2),\"kg/hr\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Saving of coal: 57.03 kg/hr\n"
]
}
],
"prompt_number": 36
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 18, page no. 497"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
"\n",
"#Variable Declaration: \n",
"r = 5000 #Rate at which steam is generated(in kg/hr):\n",
"p = 20 #Pressure of steam(in bar):\n",
"x = 0.98 #Dryness fraction:\n",
"T = 60 #Temperature of feed water(in \u00b0C):\n",
"r1 = 600 #Rate at which coal is supplied(in kg/hr):\n",
"r2 = 16 #Rate at which air is supplied(in kg per kg coal):\n",
"C = 30000 #Cslorific value of coal(in kJ/kg):\n",
"Tr = 20 #Temperature of boiler room(in \u00b0C):\n",
"nl = 0.86 #Fraction of heat losr with flue gases:\n",
"Cpg = 1.005 #Specific heat of flue gases(in kJ/kg.K):\n",
"#From steam tables:\n",
"hf = 908.79 #kJ/kg\n",
"hfg = 1890.7 #kJ/kg\n",
"\n",
"#Calculations:\n",
"ms = r/r1 #Mass of steam genrated per kg of coal:\n",
"hfi = hf+x*hfg #Enthalpy of final steam produced(in kJ/kg):\n",
"hfw = 251.13 #Enthalpy of feed water(in kJ/kg):\n",
"Q = ms*(hfi-hfw) #Heat used for steam generation(in kJ per kg of coal):\n",
"Ql = C-Q #Heat lost per kg of coal:\n",
"Qlf = nl*Ql #Heat lost with flue gases(in kJ per kg of coal):\n",
"Tgas = Tr+Qlf/((r2+1)*Cpg) #Temperature of flue gases(in \u00b0C):\n",
"\n",
"#Results:\n",
"print \"Temperature of flue gases: \",round(Tgas,2),\" \u00b0C\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Temperature of flue gases: 476.99 \u00b0C\n"
]
}
],
"prompt_number": 38
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example 19, page no. 498"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"from __future__ import division\n",
" \n",
"#Variable Declaration: \n",
"Ta = 20+273 #Ambient temperature(in K):\n",
"V = 20 #Velocity(in m/s):\n",
"hw1 = 30 #Draught lost through grate(in mm of water column):\n",
"nm = 0.80 #Mechanical efficiency:\n",
"mf = 1000 #Rate at which coal is burnt(in kg/hr):\n",
"ma = 16 #Rate at which air is supplied(in kg/hr):\n",
"pa = 1.01325 #Ambient pressure(in bar):\n",
"d = 1.29 #Density of air(in kg/m**3):\n",
"g = 9.81 #Acceleration due to gravity(in m/s**2):\n",
"T0 = 273 #Zero temperature(in K):\n",
"\n",
"#Calculations:\n",
"P1 = d*V**2/2 #Pressure equivalent to velocity head(in N/m**2):\n",
"P = P1/g #mm of water column\n",
"hw = hw1+P #Total draught loss(in mm of water column):\n",
"p = hw*g #Pressure required(in N/m**2):\n",
"PFD = p*mf*ma*Ta/(d*T0*nm*3600) #F.D. fan power requirement(in W):\n",
"\n",
"#Results:\n",
"print \"F.D. fan power: \",round(PFD/10**3,2),\"KW\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"F.D. fan power: 2.55 KW\n"
]
}
],
"prompt_number": 40
}
],
"metadata": {}
}
]
}