Read>>>>>Boiler and calculations
Boiler
1-Boiler efficiency direct method
Boiler efficiency = (Mass of steam flow X Steam enthalpy-Feed water flow at economizer inlet X Enthalpy-Attemperator water flow X Enthalpy) / (GCV of fuel X Fuel consumption)
2-Boiler efficiency by indirect method
Boiler efficiency = 100-Various losses
3-Theoretical air requirement for combustion
Theoretical air Thair = ((11.6 X C% + (34.8 X (H2-O2/8)) + (4.35 X %S))/100
Where C = % of carbon in fuel
H2 = % of Hydrogen present in fuel
S = % of sulphur present in fuel
4-Excess air requirement for combustion
%EA = O2% / (21-O2%)
Where O2 = % of oxygen present in flue gas
5-Mass of actual air supplied
AAS = (1 + EA / 100) X Theoretical air
6-Mass of flue gas
Mfg = Mass of Air + 1
6-Mass of dry flue gas
Mfg = Mass of Co2 in flue gas + Mass of Nitrogen in fuel + Mass of Nitrogen in combustion air + Mass of oxygen in flue gas + Mass of So2 in flue gas
Mfg =(Carbon % in fuel X Molecular weight of CO2 / Mol.weight of Carbon) + N2 in fuel + (Mass of actual air supplied X % of N2 in air i.e 77/100) + ((Mass of actual air – Mass of theoretical air) X 23/100) + S2 in fuel X Mol.weight of SO2 / Mol.weight of sulphur)
7-% of heat loss in dry flue gas
Heat loss = Mfg X Cp X (Tf-Ta) X 100 / GCV of fuel
Where,
Mfg = Mass of flue gas
Cp = Specific heat of flue gas in kacl/kg
Tf = Temperature of flue gas
Ta = Ambient air temperature
9-% of heat loss due to moisture in fuel
Heat loss = M X (584 + Cp X (Tf-Ta)) X 100 / GCV of fuel
Where,
M = Moisture in fuel
Cp = Specific heat of flue gas in kcal/kg
10-% of heat loss due to moisture in air
Heat loss = AAS X humidity X Cp X (Tf-Ta) X 100/ (GCV of fuel)
Where,
AAS = Actual air supplied for combustion
Cp = Specific heat of flue gas in kcal/kg
Tf = Temperature of flue gas
Ta = Ambient air temperature
11-% of Boiler water blow down
Blow down % = (Feed water TDS X % of makeup water) X 100 / (Maximum permissible TDS in Boiler water –Feed water TDS)
12-Steam velocity in line
Velocity of steam in pipe line,V = Steam flow in m3/sec / Area of pipe line (A)
Steam flow in m3/sec = (Steam flow in kg/hr / Density of steam X 3600)
Area of pipe, A = Pi X D2 / 4
Where D is pipe internal diameter
Read more>>>>>Boiler erection and commissioning guide
13-Condensate flash steam calculation
Flash steam % = (H1-H2) X 100 / Hfg)
Where, H1 = Sensible heat at high pressure condensate in kcal/kg
H2 = Sensible heat of steam at low pressure in kcal/kg
Hfg = Latent heat of flash steam
14-Calculation of amount of heat required to raise the water temperature
Heat required in kcal=Mw X Cp X (T2-T1)
Where, Mw = Mass of water
Cp = Specific heat of water in kcal/kg (1 kcal/kg)
T1 = Initial temperature of water in deg C
T2 = Final temperature of water in deg C
15-Calculation of heat required to raise air temperature
Heat required in kcal=Mair X Cp X (T2-T1)
Where, Mw = Mass of water
Cp = Specific heat of flue gas in kcal/kg (0.24 kcal/kg)
T1 = Initial temperature of air in deg C
T2 = Final temperature of air in deg C
16-Surface heat loss calculation
S = (10 + (Ts-Ta) / 20) X (Ts-Ta) X A
S = Surface heat loss in kcal/hr m2
Ts= Hot surface temperature in deg C
Ta = Ambient air temperature in deg C
17-Dryness fraction of steam
X = Mass of dry steam / (Mass of dry steam + Mass of water suspension in mixture)
18-Heat content in wet steam
h = hf + xhfg
h= Heat content in saturated steam
x = Dryness factor of steam
Hfg =Enthalpy of evaporation
19-Heat content in dry saturated steam
h = hf + hfg
h= Heat content in saturated steam
Hfg =Enthalpy of evaporation
20-Heat content in superheated steam
h = hf + hfg + Cps (Tsup - Ts)
h= Heat content in super heated steam
hfg =Enthalpy of evaporation
Cps = Specific heat of super heated steam
Tsup= Superheated steam temperature in deg C
Ts = Saturated temperature of steam in deg C
21-Calculation of Equivalent evaporation
Me = Ms X (h-hf) / hfg
Ms = Mass of steam
h = Steam enthalpy
hf= Feed water enthalpy
22-Factor of evaporation
Fe = (h-hf) / 539
23-Ash (Total) generation calculation
Ash generation in TPH = Fuel consumption per hour X % of ash in fuel / 100
24-Fly ash generation calculation
Fly ash generation in TPH = Fuel consumption per hour X % of ash in fuel X 80% / 100
25-Bottom ash generation calculation
Bottom ash generation in TPH = Fuel consumption per hour X % of ash in fuel X 20% / 100
26-Calculation of ash generation in ESP
Ash generation in ESP in TPH = Fuel consumption per hour X % of ash in fuel X 80% X 80% / 100
27-Boiler safety valve blow down calculation
Blow down % = (Set pressure - Re seat pressure) X 100 / Set pressure
28-Calculation of attemperator water flow
Attemperator water flow in TPH= Steam flow in TPH X (h1-h2) / (h2-h3)
h1 = Enthalpy of steam before desuper heating in kcal/kg
29-Economiser efficiency calculation
ηEco. = (Economiser outlet feed water temperature-Economizer inlet feed water temperature ) X 100 / (Economizer inlet flue gas temperature - Economizer inlet feed water temperature)
30-APH efficiency calculation
APH air side efficiency
ηAPHa = (Air outlet temp-Air inlet temp)) X 100 / (Flue gas inlet temperature -Air inlet temperature)
APH gas side efficiency
ηAPHg = (Flue gas inlet temp.-Flue gas outlet temp) X 100 / (Flue gas inlet temperature -Air inlet temperature )
31-Calculation of steam cost
Steam cost per ton = Steam enthalpy in kcal/kg X Fuel price per ton/ (Boiler efficiency % X GCV of fuel used in kcal/kg)
32-Travelling grate Boiler heating surface calculation
Boiler heating surface (Appx) = Boiler capacity in kg/hr / 18
Read more>>>>>Boiler service, repair and maintenance
33-AFBC Boiler heating surface calculation
Boiler heating surface (Appx) = Boiler capacity in kg/hr / 22
34-Travelling grate slop fired Boiler heating surface calculation
Boiler heating surface (Appx) = Boiler capacity in kg/hr / 12
35-AFBC slop fired Boiler (Low pressure up to 10 kg/cm2 WP) heating surface calculation
Boiler heating surface (Appx) = Boiler capacity in kg/hr / 8.2
36-Calculation of draught produced in Chimney
Hw = 353 X H (1/Ta – 1/Tg (Ma+ 1)/Ma)
H = Chimney height in meters
Ta = Atmospheric temperature in K
Tg = Flue gas temperature in K
Ma = Mass of air & Mass of flue gas = Ma+1
Also given as;
P = 176.5 X H / Ta
Hw = Chimney height in meters
Ta = Absolute atmospheric temperature in Kelvin
Hw = Draught in mmwc
37-Calculation of mass of flue gas flowing through chimney
Mg (kg/sec)= Density of gas (kg/m3) X Area of Chimney (m2) X Velocity of flue gas in Chimney (m/sec)
38-How to calculate the quantity of De-aerator venting steam?
De-aerator vent rate = 10.98 X Absolute pressure in deaerator X (D X D) Diameter of venting line orifice….Kg/hr
Note: Pressure in PSI
Diameter in inches
Or.
Steam venting flow = 24.24 X P(absolute pressure in PSI) X D X D (Size orifice in inch)........Lbs/hr
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