Mastodon Power plant and calculations

Formulae for Boiler 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

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

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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Quick troubleshooting guide for steam Turbines.


                         








  Quick troubleshooting guide for steam Turbines

SL No.

Problem

Root cause

Remedy/Action to be taken

 

 

 

 

 

 

 

   1

 

 

 

 

 

 

 

High bearing vibrations

High lube oil temperature

Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations

More clearance in bearing

Maintain bearing clearance within the limit as recommended by OEM

Contaminants/burs in oil

1.Ensure oil centrifuge is in service and is running in clarification mode

2.Get tested the oil parameters yearly and ensure all parameters are within limit

Over load operation

Operate the Turbine at or within its maximum capacity

Malfunction of the vibration sensor

Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.

 

 

 

 

 

 

2

 

 

 

 

 

High bearing temperature (Journal)

High lube oil temperature

Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations

Low lube oil pressure

Maintain correct lube oil pressure at all bearing inlet

Over load operation

Operate the Turbine at or within its maximum capacity

Less clearance in bearing

Maintain bearing clearance within the limit as recommended by OEM

Malfunction of the temperature sensor

Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.

 

 

 

 

 

 

 

 

 

 

3

 

 

 

 

 

 

 

 

 

High bearing temperature (Thrust)

High lube oil temperature

Maintain normal lube oil temperature 40-42 deg C or as per OEM recommendations

Low lube oil pressure

Maintain correct lube oil pressure at all bearing inlet

Operation of the Turbine at more exhaust flow (Active side thrust side bearing temperature will increase)

Operate the turbine well within the designed/OEM recommended steam flow

Operation of the Turbine at more extraction or bleed steam flow (Non-active side thrust bearing temperature will increase)

Operate the turbine well within the designed/OEM recommended steam flow

Improperly set Rotor during overhauling

Rotor centring should be corrected during overhauling

Malfunction of the temperature sensor

Get confirm the high bearing vibrations are due to malfunction, if confirmed ensure tightness of all connections.

    4

High axial displacement

Operation of the Turbine at more extraction or bleed steam flow or exhaust flow

Operate the turbine well within the designed/OEM recommended steam flow

  

 

 

 

 

 

 

 

   5

 

 

 

 

 

 

 

Turbine Over speed/High speed

Sudden load throw/off

Tuning governing system/actuator to avoid over speeding of rotor during sudden load through off or trips

Improperly set control valves

Proper setting of control/throttle valves

ESV & HP-valves Passing (Turbine rotor can go over speed if ESV does not close properly after tripping of Turbine)

Servicing of throttle (HP) valves & ESV during Turbine overhauling

Malfunction of Governor and control system

Re-tuning of Governor system

Stuck up of control/throttle valves

Checking Burs & foreign materials in control valves seating ensure no accumulation of dust over there.

  

 

 

 

 

 

 

 

 

 

 

 

   6

 

 

 

 

 

 

 

 

 

 

 

Turbine running at Low vacuum/exhaust pressure

Condenser cooling (MCWP) water flow/pressure low

Increase MCWP flow and pressure

Low pressure of ejector motive steam

Increase ejector steam pressure & maintain ejector steam pressure as per OEM recommended

More Cooling water temperature

1.Increase cooling water flow

2.Increase CT fans speed

3.Operate one more CT fan of required

Gland sealing steam pressure less

Increase gland steam pressure & maintain as per OEM recommended.

Note: Worn out labyrinths’ seals may call for more gland steam pressure than normal recommended

Operation of the Turbine at more condensing load (Exhaust steam flow to condenser is more)

Reduce the exhaust steam flow & operate the Turbine at optimum exhaust steam flow to condenser

Worn out ejector nozzles

Replacement of ejector nozzles during shutdowns

Atmosphere air ingress in condensate system

Check & Arrest air ingress (Check all valves gland, flanges, pipe line flanges, safety/relief valves, CEP strainer flanges)

Ejector condenser tubes leakage

Check & replace or plug the leaked tubes

Ejector vacuum steam traps not working properly

Check the traps & adjust steam flow properly. If required service the steam traps

 

 

 

 

 

 

 

 

 

 

 

  7

 

 

 

 

 

 

 

 

 

 

 

Sudden drop of vacuum

MCWP trip/Cooling water flow reduced

Start stand by pump or increase the flow

Sudden increase in condenser load/ More exhaust steam flow to condenser

Reduce turbine load

Increase cooling water flow

Then normalise the Turbine load

Ejector steam pressure reduced

Increase & maintain ejector steam pressure

Gland sealing steam pressure reduced

Check gland sealing steam control valve & normalise the steam pressure

Air ingress in condensate system

Check possible ingress points & arrest the leakages.

 

Potential points for Air ingress are;

1-Air ingress from CEP suction strainer

2-Vacuum breaker valves

3-Ejector safety/relief valves

4-Glands & flanges of valves

All the CT fans tripped or stopped

Check & start the fans

Vacuum breaker valve open/malfunction/passing

Check the valve and close properly

 

 

 

 

 

 

   8

 

 

 

 

 

 

 Hot well level rising

Sudden drop of vacuum

Check the root cause of vacuum drop ( MCWP pump trip or less cooling water flow, ejector steam pressure low etc) and correct it.

CEP pump tripped

Ensure stand by pump is in AUTO mode & has started immediately

Air lock in running CEP

Check the reason for air ingress

Prime the pump & restart

Hot well level control valve stuck or malfunction

Check & rectify the valve issue

CEP to D/A control valve stuck or malfunction

Check & rectify the valve issue

 

 

 

 

   9

 

 

 

 

Low hot well level

Sudden increase in extraction steam flow

Reduce extraction steam flow

Hot well level control valve closed/stuck/malfunction

Check and open the hot well level control valve

CEP to Deaerator control valve stuck/mal function

Check and rectify the issue

Sudden start of stand by pump

Check and stop the pump if not required

 

 

 

 

 

 

 

   10

 

 

 

 

 

Low lube oil pressure

Running oil pump tripped

Ensure stand by pump is in AUTO mode & has started immediately

PRV stuck or malfunction

Check & rectify the valve issue

Oil leakage

Check & arrest oil leakage

Air lock in running pump

Start tart the stand by pump if not started in AUTO and then prime the pump.

High lube oil temperature

Maintain lube oil temperature within normal limit (40-45 deg C)

Lube oil filter clogged

Change over the oil filter

Clean the filter

 

 

 

 

   11

 

 

 

 

Low Control oil pressure

Running oil pump tripped

Ensure stand by pump is in AUTO mode & has started immediately

PRV stuck or malfunction

Check & rectify the valve issue

Oil leakage

Check & arrest oil leakage

Air lock in running pump

Start tart the stand by pump if not started in AUTO and then prime the pump.

Control oil filter clogged

Change over the oil filter

Clean the filter

 

 

  

 

    12

 

 

 

 

High lube oil temperature

Lube oil cooler outlet valve throttled

Open the cooling water outlet valve as per requirement

Less cooling water flow to Oil cooler

Ensure oil cooler inlet cooling water valve is open 100% & outlet valve is throttled as per requirement

Less cooling water flow or low ACWP pressure

Increase the cooling water flow & pressure

Poor heat transfer in oil cooler or tubes fouling

Tubes cleaning & back wash

  

 

 

 

 

 

 

 

   13

 

 

 

 

 

 

 

Turbine load/speed hunting

Variation in extraction steam pressure

Maintain extraction steam pressure & flow constant-Talk with end user or process steam.

Burs on actuator spindles

Clean the actuator shaft & Ensure oil purification unit is in service

Control oil pressure fluctuation

Ensure accumulator is healthy and its operating pressure is at least 85-90% of control oil operating pressure.

Contamination in oil

Ensure oil purification unit is in service.

Improper tuning of governor

Tune the Governor properly

Tightness in actuator links/resistance in the movement of linkages

Clean & lubricate the actuator linkages & ensure free movement

 

 

  14

More specific steam consumption of Turbine

Pressure & Temperature of main steam are low

Maintain the correct pressure & temperature

Low vacuum

Maintain the vacuum on higher side

High exhaust temperature

Maintain the exhaust temperature in the range of 40-50 deg C or as per exhaust pressure

Operation of the Turbine at lower/partial loads

Operate the Turbine at higher loads or at full capacity

More clearance in labyrinth seals

Maintain OEM recommended clearance between rotor & casing during Turbine major overhauling

More extraction steam flow than recommended

Reduce the extraction flow & maintain as per HMBD

More bleed steam flow than recommended

Reduce the bleed steam flow & maintain as per HMBD

 

 

 

   15

 

 

 

High wheel chamber pressure

Scaling of rotor blades

1-Maintain water and steam quality as per design

2-Descaling of rotor blades during Turbine overhauling

Less clearance in labyrinth seals

Maintain OEM recommended clearance between rotor & casing during Turbine major overhauling

15-Emergencies in power plant operation

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