How do you calculate Steam turbine heat rate and efficiency???

 

How do you calculate the Turbine efficiency?

 Turbine efficiency is the ratio of heat out put to the heat input

Here, heat input is heat content in inlet steam and out put is power generation.

Actually, total  power generation =Power generated on generator terminal / (Gear box efficiency X Alternator efficiency).

 What is Turbine heat rate?

Turbine heat rate is the ratio of total heat required to generate unit power.

 Turbine efficiency = 860 X 100 / Turbine heat rate

 Thermal power plant turbine heat rate

 = Steam flow (Main steam enthalpy-Feed water enthalpy) / Power generation

 Co-generation Turbine heat rate:

 =((Steam Flow x Steam Enthalpy +Makeup Water flow x Its Enthalpy+ RC Flow x RC Enthalpy)-(Process-1 steam flow x its Enthalpy + Process-2 steam flow x Its Enthalpy+ FW Flow x FW Enthalpy)) /Power Generation

 Co-generation Turbine heat rate is also calculated as;

 ((Steam Flow x Steam Enthalpy)-(1St EXT Flow x Its Enthalpy + 2nd Ext flow x its Enthalpy + 3rd Ext flow x Its Enthalpy+ Exhaust Steam flow x its Enthalpy)) /Power Generation

 Calculations:

 A thermal power plant is generating 55 MW power at specific steam consumption 3.7 MT/MW and at pressure and temperature 110 kg/cm2 and 540 deg C respectively.Calculate the Turbine heat rate and  efficiency if its feed water inlet temperature at economizer is 215 deg C

 Turbine inlet steam flow = 55 X 3.7 = 203.5 TPH

Enthalpy of inlet steam at rated pressure and temperatures = 821 kcal/kg

Enthalpy of feed water = 217 kcal/kg

 Thermal power plant turbine heat rate= Steam flow (Main steam enthalpy-Feed water enthalpy) / Power generation

THR = 203.5 X (821-217) / 55

THR = 2234.8 kcal/kwh

 Turbine efficiency = 860 X 100 / 2234.8

Turbine efficiency = 38.48%

 A back pressure turbine is generating 7.5 MW load at specific steam consumption 7.5 MT/MW, calculate the turbine heat rate and efficiency if inlet steam pressure and temperatures are 64 kg/cm2 and 485 deg C and exhaust steam parameters are 4 kg/cm2 and 165 deg C

 Inlet steam flow = 7.5 X 7.5 = 56.25 TPH

Enthalpy of inlet steam= 810 kcal/kg

Enthalpy of exhaust steam = 665 kcal/kg

 Turbine heat rate = (Inlet steam flow X Enthalpy-Exhaust steam flow X Enthalpy) / Power generation

Turbine heat rate =(56.25 X 810-56.25 X 665) / 7.5

Turbine heat rate = 1087.5 kcal/kw

Turbine efficiency = 860 X 100/ Heat rate

                                 = 860 X 100/1087.5

                                 = 79%

 The operation details of a 22 MW condensing cum extraction turbines are as below, calculate its heat rate & efficiency

 

SL No	Particular	UOM	Value
1	Turbine inlet steam pressure	Kg/cm2	88
2	Turbine inlet steam temperature	Deg C	515
3	Turbine inlet steam flow	TPH	120
4	Process steam flow	TPH	65
5	Process steam pressure	Kg/cm2	2.0
6	Process steam temperature	Deg C	140
7	Exhaust steam pressure	Kg/cm2	-0.88
7a	Exhaust steam flow	TPH	55
8	Process return condensate flow	TPH	58
9	Process condensate temperature	Deg C	115
10	DM Make up water flow	TPH	9
11	DM Make up water temperature	Deg C	27
12	Feed water flow	TPH	121
13	Feed water temperature	Deg C	145

 Solution:

 Enthalpy of turbine inlet steam = 818 kcal/kg

Enthalpy of process steam =655 kcal/kg

Enthalpy of feed water= 147 kcal/kg

Enthalpy of return condensate=116 kcal/kg

Enthalpy of DM water = 25 kcal/kg

Enthalpy of exhaust steam in( liquid form) = 52 kcal/kg

 Co-generation Turbine heat rate:

 =((Steam Flow x Steam Enthalpy +Makeup Water flow x Its Enthalpy+ RC Flow x RC Enthalpy)-(Process-steam flow x its Enthalpy + FW Flow x FW Enthalpy)) /Power Generation

 =((120 X 818 + 9 X 25 + 58 X 115)-(65 X 655 + 121 X 147)) / 22

=2031.5 kcal/kg

 Turbine efficiency = 860 X 100 / 2031.5

                                 = 42.33%

 Same can be calculated by another formula

 THR=((Steam Flow x Steam Enthalpy)-(EXT Flow x Its Enthalpy ++ Exhaust Steam flow x its Enthalpy)) /Power Generation

THR =(120 X 818 -65 X 655 - 55 X 52) / 22

THR =2396.5 kcal/kg

Turbine efficiency = 860 X 100 / 2396.5

                                 = 35.88%

Read more>>>powerplant and calculations

How do you calculate power plant efficiency???

 Efficiency of the power plant is calculated based on heat input and out put.

 Power plant efficiency = Heat out put X 100 / Heat out put

In power plant, generally heat input is fuel, make up water and condensate return water from process.

Heat out put is power generation.

The formula for efficiency calculation is different for different plants.

Efficiency of the power plant is given as

Efficiency = 860 X 100 / Heat rate

 1-For thermal power plants efficiency is calculated as;

 Efficiency = 860 X Power generation / Heat input

Efficiency = 860 X PG X 100 / (Fuel consumption X Fuel GCV)

 2-For co generation plants heat rate is calculated as;

 Efficiency = 860 X Power generation X 100 / (Fuel consumption X GCV + Make up water X Make up water enthalpy + Return condensate water X Enthalpy-Process steam flow X Enthalpy)

 3-Cogen plant Efficiency is also calculated as;

 Efficiency = 860 X Boiler efficiency X 100 / Turbine heat rate

 Calculation:

 1.Calculate the efficiency of power plant having heat rate 3451 Kcal/kwh

 Efficiency of the power plant = 860 X 100 / Heat rate

Efficiency of the power plant = 860 X 100 / 3451

Efficiency of the power plant = 24.92%

Read power plant O&M reference books

 2.A 75 MW Thermal power plant consumes 1100 MT coal per day, calculate the plant efficiency, consider the GCV of coal 5000 Kcal/kg

 Efficiency of the plant = 860 X 24 X 75 X 100 / (1100 X 5000)

Efficiency of the plant = 28.15%

 3. A 29 MW thermal power plant is having Turbine of heat rate 2798 kcal/kwh, which consumes steam at the rate of 4.2 MT/MW from a boiler having efficiency 69%.Calculate the efficiency of power plant

 Efficiency = 860 X Boiler efficiency X 100 / Turbine heat rate

Efficiency = 860 X 0.69 X 100 / 2798

Efficiency = 21.2%

How do you calculate Steam turbine heat rate and efficiency???

 4. A 30 MW biomass Co generation plant consumes 1750 MT fuel per day and supplies 2880 TPH steam to process at pressure 2 kg/cm2 & 135 deg C, in turn receives 90% return condensate at 119 deg C temperature.The make up water for this plant is 610 m3 at temperature 27 deg C.Calculate the efficiency of the plant, consider GCV of biomass fuel 2250 kcal/kg.

 Efficiency of Co-gen plant  = 860 X Power generation X 100 / (Fuel consumption X GCV + Make up water X Make up water enthalpy + Return condensate water X Enthalpy-Process steam flow X Enthalpy)

 Enthalpy of process steam at 2 kg/cm2 and 135 deg C is 652 kcal/kg

Enthalpy of return condensate water is 121 kcal/kg

Enthalpy of make up water at 27 deg C is 27.2 kcal/kg

 Efficiency of Co-gen plant  = 860 X 30 X 24 X 100 / (1750 X 2250 + 610 X 27.2 + 2880 X 80% X 121 X 2880 X 652)

Efficiency of Co-gen plant  = 860 X 30 X 24 X 100 / (1750 X 2250 + 610 X 27.2 + 2880 X 80% X 121 - 2880 X 652)

Efficiency of Co-gen plant = 26.29%

 5. A thermal power plant operating at 125 MW operating  at pressure 110 kg/cm2 and temperature 545 deg C.A AFBC boiler of efficiency 84% consumes 379 TPH Feed water at temperature 200 degC to generate 375 TPH steam.Calculate the efficiency of the thermal power plant.

 We have, Turbine heat rate = (Inlet steam flow X Enthalpy-Feed water flow X Enthalpy) / Power generation

 Turbine heat rate = 375 X 821-379 X 202) / 125

 Turbine heat rate = 1850.5 kcal/kwh

 Turbine efficiency = 860 X 100 / 1850.5

Turbine efficiency = 46.5%

 Power plant efficiency = Turbine efficiency X Boiler efficiency = 46.5 X 0.84 =39.06%

 For more calculations read Powerplant and calculations

Read Power plant O&M reference books

Practical Approach to Power Plant Operation and Maintenance

How do you calculate the efficiency of Air pre heater (APH) in Boilers??

 

APH is an auxiliary used in steam generators or boilers to increase the Boiler efficiency and to reduce the fuel consumption.

There are different types of air heaters. Major types are tubular & regenerative air preheater.

These may be installed horizontally or vertically as per requirement.

In some design of APH air flows outside the tubes and flue gas inside the tubes where as in some cases air flows inside the tubes and flue gas outside of the tubes.

The main functions of APH is to reduce the flue gas temperature to allowable limit that is coming out from Boiler and to increase combustion air temperature.

The efficiency of the APH are calculated from two ways one is from air side other from gas side.

APH gas side efficiency

ηAPHg = (Flue gas inlet temp.Tfi-Flue gas outlet temp.Tfo) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 

APH air side efficiency

ηAPHa = (Air outlet temp.Tao-Air inlet temp.Tao)) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 Read power plant O&M reference books

Calculate the APH gas side & air efficiency if its flue gas inlet and out let temperature are 230 deg C and 145 deg C and air inlet and out let temperatures are 28 deg C & 180 deg C respectively.

ηAPHg = (Flue gas inlet temp.Tfi-Flue gas outlet temp.Tfo) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 

ηAPHg =(230-145) X 100 / (230-28)

ηAPHg = 42.1%

ηAPHa = (Air outlet temp.Tao-Air inlet temp.Tao)) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 

ηAPHa = (180-28) X 100 / (230-28)

ηAPHa = 75.24%

Read Economiser efficiency calculation

A Tubular type APH is having air side efficiency 79%, its flue gas and air inlet temperature are 225 deg and 30 deg C respectively, calculate the APH outlet air temperature

We have,

ηAPHa = (Air outlet temp.Tao-Air inlet temp.Tao)) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 

79% = (Tao-30) X 100 / (225 – 30)

Tao-30 = 0.79 X 195

Tao = 184.05 deg C

A Tubular type APH is having gas side efficiency 39%, its flue gas and air inlet temperature are 225 deg and 30 deg C respectively, calculate the APH outlet flue gas temperature

We have,

ηAPHg = (Flue gas inlet temp.Tfi-Flue gas outlet temp.Tfo) X 100 / (Flue gas inlet temperature tfi-Air inlet temperature Tai)

 

39% = (225-Tfo) X 100 / (225-30)

0.39 X 195 = 225-Tfo

Tfo = 148.95 deg C

Read power plant and calculations

How do you carryout performance Guarantee (PG) test of power plant equipments??

 

What do you mean by performance Guarantee (PG) test?

 It is a test carried out to measure the performance of an equipment as guaranteed by the manufacturer.

What are the equipments on which PG test is carried out in power plants?

Generally all the equipments should met manufacturer guarantee performance value, but in Power plant, Boiler, Turbine & Generators are the major & critical equipments where PG tests are carried out.

When & who do carryout PG test?

PG test is carried out after erection & commissioning of the equipments and before hand over of the equipments PG test is carriedout.PG test is carried out. It is carried out by Original Equipment Manufacturer (OEM).

How do you carryout PG test?

For conducting the PG test, some parameters are measured & compared with standard design & operating values. Before conducting PG test, it is mutually agreed between OEM & Owner what parameters to be measured & means of measurement. And also it is mutually agreed that, how much time this test will be conducted. In some cases PG test is conducted for 8 hours, in some cases 24 hours.

And also the frequency of parameters measurement is decided before commence of PG test.

Procedure for PG test.

Testing Methodology: Standard testing methodology is decided

Testing equipment: Type of equipment, its measuring accuracy & calibration reports

Tolerance: The margin of error.

Ambient temperature: It is most important for conducting PG test since all the equipments & systems are designed on the basis of atmospheric temperature.

Parameters Log sheet & List of Operation team to be involved in PG tests are decided before the test.

Once the PG test completes, log sheets are collected & should be signed by owner & OEM for future reference.

What is the significance of carrying out PG test in Boilers?

PG test is carried out to ensure following key performance Indicators (KPIs) of Boiler

• Specific fuel consumption of the Boiler or steam to fuel ratio (SFR)
• Steam Purity
• Steam pressure & temperature at various operating condition
• Boiler efficiency
• Load stability during various load demand
• Stack gas quality
• Minimum & maximum rating

What parameters are measured during Boiler PG test?

• Steam pressure & temperature
• Steam flow & feed water flow
• Fuel consumption
• Attemperator/Desuper heater water flow
• Feed water parameters like pH, conductivity, silica, Hydrazine
• Boiler Water parameters like pH, conductivity, silica, Phosphate
• Steam parameters like pH, conductivity, silica etc
• Feed water temperature at Deaerator outlet
• Feed water temperature at Economiser inlet
• Exhaust flue gas temperature
• Excess air & O2% in flue gas
• Flue gas parameters like SPM, SOx, NOx etc
• ESP & APH inlet & outlet flue gas temperature for air leakage test
• Combustion air temperature after APH
• Unburnt level in ash
• CBD water flow
• Drum level
• Boiler auxiliary power consumption
• Operating % of load Fans& fuel feeding system at various Boiler load.

In this test, a boiler is allowed to generate steam at various load conditions. Its capability to generate steam at required parameters and required efficiency is checked.

Note: While conducting Boiler PG test, input parameters like fuel moisture, GCV etc kept as per design values

What is the significance of carrying out PG test in Turbines?

PG test is carried out to ensure following key performance Indicators (KPIs) of Boiler

• Specific steam consumption (SSC)
• Exhaust steam temperature
• Condenser vacuum
• Heat rate & efficiency
• Turbine bearing vibrations & temperature
• HP valve demand during various load demand
• Turbine Noise level
• Stability during sudden load cut off
• Steam pressure & temperature of extraction & bleed steam
• Turbine auxiliary power consumption

What parameters are measured to conduct PG test of steam Turbine?

• Turbine inlet steam pressure & temperature
• Turbine inlet steam flow
• Auxiliary steam flow
• Condenser inlet & outlet cooling water temperature
• Turbine & Gear box all bearings & vibrations
• Noise level around turbine
• Load on Generator
• Oil cooler inlet & outlet water & oil temperature
• HP & LP valve lift & demand
• Turbine casing thermal expansion
• Wheel chamber pressure
• Pressure, temperature & steam flow of extraction & bleed steam
• Exhaust steam pressure, temperature and flow

What parameters are checked for PG test of Generators?

• Generator output power
• Terminal voltage
• Frequency
• Current
• Power factor
• Winding & air temperature
• Air cooler inlet & outlet water temperature

 

 Read.

Power plant equipments SOP

Power plant & calculations.

 

 

Standard Operation Procedure of Oil filter & oil Cooler change over

 

SOP: Oil Filter Change Over

Follow the below mentioned steps for changeover of filter.

This procedure is valid for duplex filter.

• Ensure Filter DP is high enough to change the running filter to stand by filter.
• Ensure that stand by filter is provided with filter element, which is cleaned or replaced with a new one.
• Open the vent of the standby filter.
• Crack- open the filter equalizer line.
• See that air is coming out of filter, close vent as soon as full bore liquid comes out of it.
• Operate change over mechanism.
• Observe that filter DP has come down to minimum DP position in the indicator.
• Close the equalizer line.
• Clean the choked filter & keep ready for immediate use.

SOP: Cleaning of Choked oil Filter Element

Follow below steps to clean or replace filter element.

• Open drain and vent of choked filter.
• Ensure complete draining of filter body.
• Open the filter flange and remove the filter element(s).
• Clean the filter body from inside.
• Clean the filter element with fresh water/ petrol and dry it with dry air, if it is a reusable filter or use new cartridge if it is a non-reusable one.
• Close the filter flange.

Oil Cooler Change Over

This procedure is valid where duplex type oil cooler is provided. When running cooler is required to do maintenance due to leakage, non-performing etc., it needs to change over to standby one. Proceed as per below mentioned steps for cooler change operation.

• Ensure stand-by one ready for operation.
• Ensure stand-by oil cooler vents on both tube and shell side of the cooler is open.
• Ensure the cooler drains are closed.
• Charge Cooling water in the cooler and close waterside vents after removing entrapped air.
• Open cooler oil equalizer line. It takes some times to fill a cooler.
• Close oil vent once entrapped air is completely removed.
• Operate change over mechanism.

Check all the parameters of oil and cooling water.

Control oil temperature by operating CW valve.