Analysis of Steam Cycles

Analysis of Steam Cycles

Dr. Rohit Singh Lather, Ph.D.

Constant Pressure Steam Generation ProcessConstant Pressure Steam Generation ProcessConstant Pressure Steam Generation ProcessConstant Pressure Steam Generation Process

Theory of flowing Steam Generation

vdpdhq

qHVm fuelSG

Constant Pressure Steam Generation:

vdpdhq = 0

Types of SteamTypes of SteamTypes of SteamTypes of Steam

Sensible HeatSensible Heat

It should be noted that thepoints 2 and 3 are at thesame boiling pointtemperature and pressureand also that, at thoseconditions, the liquid and thesteam (whether wet or dry)are in equilibrium with eachother.


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It should be noted that thepoints 2 and 3 are at thesame boiling pointtemperature and pressureand also that, at thoseconditions, the liquid and thesteam (whether wet or dry)are in equilibrium with eachother.


• Wet steam: AA mixturemixture ofof waterwater plusplus steamsteam (liquid plus vapor) at the boilingpoint temperature of water at a given pressure. Quality of steam refers tothe fraction or percentage of gaseous steam in a wet steam mixture.

• Dry steam: Steam, at the given pressure, that containscontains nono waterwater (also(alsoreferredreferred toto asas saturatedsaturated steam)steam).. TheThe steamsteam qualityquality == 100100%%.. At the top ofsteam generator units for producing saturated steam, there are moistureseparators used to remove residual water droplets from outgoing steam.

• Superheated steam: Dry steam, at the given pressure, that has beenheatedheated toto aa temperaturetemperature higherhigher thanthan thethe boilingboiling pointpoint ofof waterwater atat thatthatpressurepressure..


• Wet steam: AA mixturemixture ofof waterwater plusplus steamsteam (liquid plus vapor) at the boilingpoint temperature of water at a given pressure. Quality of steam refers tothe fraction or percentage of gaseous steam in a wet steam mixture.

• Dry steam: Steam, at the given pressure, that containscontains nono waterwater (also(alsoreferredreferred toto asas saturatedsaturated steam)steam).. TheThe steamsteam qualityquality == 100100%%.. At the top ofsteam generator units for producing saturated steam, there are moistureseparators used to remove residual water droplets from outgoing steam.

• Superheated steam: Dry steam, at the given pressure, that has beenheatedheated toto aa temperaturetemperature higherhigher thanthan thethe boilingboiling pointpoint ofof waterwater atat thatthatpressurepressure..

Temperature Entropy DiagramTemperature Entropy DiagramTemperature Entropy DiagramTemperature Entropy Diagram

Latent Heat of EvaporationLatent Heat of Evaporation

• The horizontal axis is not enthalpy but instead is enthalpy divided by the meantemperature at which the enthalpy is added or removed.

• By starting at the origin of the graph at a temperature of 0°C at atmosphericpressure, and by adding enthalpy in small amounts, the graph can be built.

• As entropy is measured in terms of absolute temperature, the origin temperature of0°C is taken as 273.15 K.

• The specific heat of saturated water at this temperature is 4.228 kJ/kg K. For thepurpose of constructing the diagram in the base temperature is taken as 273 K.

• Assuming 1kg of water at atmospheric pressure, and by adding 4.228 kJ of energy,the water temperature would rise by 1 K from 273 K to 274 K. The mean temperatureduring this operation is 273.5 K.
















This value represents the change in enthalpy perdegree of temperature rise for one kilogram ofwater and is termed the change in specificentropy. The metric units for specific entropy aretherefore kJ/kg K.

This value represents the change in enthalpy perdegree of temperature rise for one kilogram ofwater and is termed the change in specificentropy. The metric units for specific entropy aretherefore kJ/kg K.

• As the temperature increases, the change in entropy for each equalincrement of enthalpy reduces slightly.

• If this incremental process were continuously repeated by adding moreheat, it would be noticed that the change in entropy would continue todecrease.

• This is due to each additional increment of heat raising the temperatureand so reducing the width of the elemental strip representing it. As moreheat is added, so the state point line, in this case the saturated waterline, curves gently upwards.










• At 373.14 K (99.99°C), the boiling point of water is reached at atmospheric pressure, and furtheradditions of heat begin to boil off some of the water at this constant temperature.

• At this position, the state point starts to move horizontally across the diagram to the right, and isrepresented by the horizontal evaporation line stretching from the saturated water line to the drysaturated steam line.

• Because this is an evaporation process, this added heat is referred to as enthalpy of evaporation.

At atmospheric pressure, steam tables state that theamount of heat added to evaporate 1 kg of waterinto steam is 2256.71 kJ. As this takes place at aconstant temperature of 373.14 K, the meantemperature of the evaporation line is also 373.14 K.

The change in specific entropy from the watersaturation line to the steam saturation line istherefore:

At atmospheric pressure, steam tables state that theamount of heat added to evaporate 1 kg of waterinto steam is 2256.71 kJ. As this takes place at aconstant temperature of 373.14 K, the meantemperature of the evaporation line is also 373.14 K.

The change in specific entropy from the watersaturation line to the steam saturation line istherefore:

1: Saturated water line.2 : Dry saturated steam line.3 : Constant dryness fraction lines in the wet

steam region.4: Constant pressure lines in the superheat

region.

H – S DiagramIsenthalpic expansion of steam through acontrol valve is simply represented by astraight horizontal line from the initialstate to the final lower pressure

The isentropic expansion of steam through anozzle is simply a line from the initial statefalling vertically to the lower final pressure.

• As the expansion through a control valve orifice is an isenthalpic process

Accelerate at high Speed

Borrowing energy from its enthalpy and converting it tokinetic energy.

HeatDrop

This part of the process isisentropic

This part of the process isisentropic

SteamSteam DeacceleratesDeaccelerates

Fall in velocity requires a reduction in kineticenergy which is mostly re-converted back intoheat and re-absorbed by the steam.

The heat drop that caused the initial increasein kinetic energy is reclaimed (except for asmall portion lost due to the effects offriction), and on the H - S chart, the state pointmoves up the constant pressure line until itarrives at the same enthalpy value as the initialcondition.

Steam Generation : Expenditure Vs WastageSteam Generation : Expenditure Vs Wastage

Liquid +Vapour

Vapour

h

s

Liquid

Variable Pressure Steam GenerationVariable Pressure Steam GenerationVariable Pressure Steam GenerationVariable Pressure Steam Generation

s

h

Pressure, MPa Enthalpy, kJ/Kg Entropy, kJ/Kg/K Temp, C Volume, m³ /kg

1 1 3500 7.79 509.9 0.3588

2 5 3500 7.06 528.4 0.07149

3 10 3500 6.755 549.6 0.03562

4 15 3500 6.582 569 0.02369

Analysis of Steam Generation at Various PressuresAnalysis of Steam Generation at Various PressuresAnalysis of Steam Generation at Various PressuresAnalysis of Steam Generation at Various Pressures

4 15 3500 6.582 569 0.02369

5 20 3500 6.461 586.7 0.01776

6 25 3500 6.37 602.9 0.01422

7 30 3500 6.297 617.7 0.01187

8 35 3500 6.235 631.3 0.0102

More Availability of EnergyMore Availability of EnergyMore Availability of EnergyMore Availability of Energy

Temp, C Pressure, MPa Volume m³/kg Enthalpy, kJ/kg Entropy, kJ/kg/K

575 5 0.0762 3608 7.191

575 10 0.03701 3563 6.831

575 12.5 0.02917 3540 6.707

575 15 0.02393 3516 6.601

575 17.5 0.02019 3492 6.507

575 20 0.01738 3467 6.422

575 22.5 0.0152 3441 6.344

575 25 0.01345 3415 6.271

575 30 0.01083 3362 6.138

575 35 0.008957 3307 6.015

6.6

6.8

7

7.2

7.4

Creation/Reduction of WastageCreation/Reduction of WastageCreation/Reduction of WastageCreation/Reduction of Wastage

5.8

6

6.2

6.4

6.6

0 10 20 30 40

s

MPap,

Less Fuel for Creation of Same TemperatureLess Fuel for Creation of Same TemperatureLess Fuel for Creation of Same TemperatureLess Fuel for Creation of Same Temperature

3500

3550

3600

3650

kgkJh,

3250

3300

3350

3400

3450

0 10 20 30 40MPap,

kgkJh,

Carnot Cycle (NoCarnot Cycle (No IrreversablitiesIrreversablities))Carnot Cycle (NoCarnot Cycle (No IrreversablitiesIrreversablities))


1. No heat device can generate work withoutwithout netnet rejectionrejection ofof heatheat toto aa lowlowtemperaturetemperature reservoirreservoir..2. It is impossible for any device that operates in a cycle toto receivereceive heatheat fromfrom aa singlesinglehighhigh temperaturetemperature reservoirreservoir andand produceproduce aa netnet amountamount ofof workwork and no other effects.

Introduction to Rankine cycleIntroduction to Rankine cycleIntroduction to Rankine cycleIntroduction to Rankine cycle

• It is difficult if not impossible, to maintainmaintain perfectperfect constantconstant temperaturetemperatureheatheat additionaddition andand heatheat rejectionrejection..

• By usingusing waterwater asas thethe workingworking fluid,fluid, andand consideringconsidering thethe latentlatent heatheatconceptconcept can closely resemble the theoreticaltheoretical CarnotCarnot cyclecycle.

•• Rankine cycle is a waterRankine cycle is a water--vapor cycle that describe the operation of steamvapor cycle that describe the operation of steampower generation system in it’s thermodynamic aspects.power generation system in it’s thermodynamic aspects.

• Rankine cycle is also referred to as a “practical Carnot cycle”“practical Carnot cycle” due to :

1. The TThe T--s diagram resembless diagram resembles the Carnot cycle.

2. Heat addition in the boiler and heat rejection in the condenser takesplace :

i– Isothermally in Carnot[ ΔT = 0 ]

ii –Isobarically in Rankine[ ΔP = 0 ]

3. Steam is converted in the condenser to saturated liquidsaturated liquid

• It is difficult if not impossible, to maintainmaintain perfectperfect constantconstant temperaturetemperatureheatheat additionaddition andand heatheat rejectionrejection..

• By usingusing waterwater asas thethe workingworking fluid,fluid, andand consideringconsidering thethe latentlatent heatheatconceptconcept can closely resemble the theoreticaltheoretical CarnotCarnot cyclecycle.

•• Rankine cycle is a waterRankine cycle is a water--vapor cycle that describe the operation of steamvapor cycle that describe the operation of steampower generation system in it’s thermodynamic aspects.power generation system in it’s thermodynamic aspects.

• Rankine cycle is also referred to as a “practical Carnot cycle”“practical Carnot cycle” due to :

1. The TThe T--s diagram resembless diagram resembles the Carnot cycle.

2. Heat addition in the boiler and heat rejection in the condenser takesplace :

i– Isothermally in Carnot[ ΔT = 0 ]

ii –Isobarically in Rankine[ ΔP = 0 ]

3. Steam is converted in the condenser to saturated liquidsaturated liquid


Rankine CycleRankine CycleRankine CycleRankine Cycle

A Rankine cycle consists of the following processes:-

• Process 4 - 1 Isentropic Compression: The workingfluid is pumped from low to high pressure.

• Process 1 - 2 Isobaric Heat Supply: The high pressureliquid enters a boiler where it is heated at constantpressure by an external heat source to become a drysaturated vapor.

• Process 2 - 3 Isentropic Expansion: The dry saturatedvapor expands through a turbine, generating power.This decreases the temperature and pressure of thevapor, and some condensation may occur.

• Process 3 - 4 Isobaric Heat Rejection: The wet vaporthen enters a condenser where it is condensed at aconstant pressure to become a saturated liquid.

A Rankine cycle consists of the following processes:-

• Process 4 - 1 Isentropic Compression: The workingfluid is pumped from low to high pressure.

• Process 1 - 2 Isobaric Heat Supply: The high pressureliquid enters a boiler where it is heated at constantpressure by an external heat source to become a drysaturated vapor.

• Process 2 - 3 Isentropic Expansion: The dry saturatedvapor expands through a turbine, generating power.This decreases the temperature and pressure of thevapor, and some condensation may occur.

• Process 3 - 4 Isobaric Heat Rejection: The wet vaporthen enters a condenser where it is condensed at aconstant pressure to become a saturated liquid.


Losses in Rankine CycleLosses in Rankine CycleLosses in Rankine CycleLosses in Rankine Cycle

• At the end of condensationcondensation thethe liquidliquid pressurepressure mustmust bebe raisedraised toto boilerboiler pressurepressure by the action ofthe feed water pump, and this is bring about the first kind of power losses.

• The pumped saturated liquid inside the boiler is out of the liquid saturation line, and therefore heatheatmustmust bebe addedadded atat constantconstant pressurepressure toto returnreturn toto saturationsaturation pointpoint, such heat added is another kindof power losses in the cycle.

• The efficiency of Rankine cycle is limited by the working fluid possible temperature range to avoidconstruction material failure, and on the other side to avoid possible condenser leakage andinability of heat removal. Such limits (Th=565 °C) and (TL = 30 °C) will results in Carnot thermalefficiency of (63%) compared to (42%) in modern coal fired power station.

• Work required by the pump consumes only ( 1 to 3 %)of the turbine power o/p, since all vapor isconverted to liquid in the condenser. However heat must be added in the boiler to raise pumpedliquid to saturation temperature. i.e

Pump work is improved →→→ thermal eff. Is increasedOverall heat added →→→ thermal eff. Is reducedTherefore, the resultant effects → is better thermal eff.

• At the end of condensationcondensation thethe liquidliquid pressurepressure mustmust bebe raisedraised toto boilerboiler pressurepressure by the action ofthe feed water pump, and this is bring about the first kind of power losses.

• The pumped saturated liquid inside the boiler is out of the liquid saturation line, and therefore heatheatmustmust bebe addedadded atat constantconstant pressurepressure toto returnreturn toto saturationsaturation pointpoint, such heat added is another kindof power losses in the cycle.

• The efficiency of Rankine cycle is limited by the working fluid possible temperature range to avoidconstruction material failure, and on the other side to avoid possible condenser leakage andinability of heat removal. Such limits (Th=565 °C) and (TL = 30 °C) will results in Carnot thermalefficiency of (63%) compared to (42%) in modern coal fired power station.

• Work required by the pump consumes only ( 1 to 3 %)of the turbine power o/p, since all vapor isconverted to liquid in the condenser. However heat must be added in the boiler to raise pumpedliquid to saturation temperature. i.e

Pump work is improved →→→ thermal eff. Is increasedOverall heat added →→→ thermal eff. Is reducedTherefore, the resultant effects → is better thermal eff.


Rankine CycleRankine CycleRankine CycleRankine Cycle

• SFEE for boiler

Q₁ = h₁ - h₄

• SFEE for turbine

Q₂ = h₂ – h₃

• SFEE for pump

Wp = h₄ – h₃

• The efficiency of Rankine cycle:

Ƞ = Wnet / Q₁= (Wt – Wp) / Q₁

= (h₁ – h₂) - (h₄ – h₃) / (h₁ - h₄)

• SFEE for boiler

Q₁ = h₁ - h₄

• SFEE for turbine

Q₂ = h₂ – h₃

• SFEE for pump

Wp = h₄ – h₃

• The efficiency of Rankine cycle:

Ƞ = Wnet / Q₁= (Wt – Wp) / Q₁

= (h₁ – h₂) - (h₄ – h₃) / (h₁ - h₄)

TheThe capacitycapacity ofof aa steamsteam powerpower plantplant isis oftenoften expressedexpressed inin termsterms ofof SteamSteamRateRate oror SpecificSpecific SteamSteam ConsumptionConsumption (S(S..SS..C)C)..

DefinedDefined asas thethe raterate ofof steamsteam flowflow (kg/s)(kg/s) requiredrequired toto produceproduce unitunit shaftshaftoutputoutput ((11 kW)kW)..

SteamSteam RateRate (S(S..RR..)) == 11//WnetWnet ;;kg/kWkg/kW ss

TheThe cyclecycle efficiencyefficiency isis sometimessometimes expressedexpressed alternativelyalternatively asas HeatHeat RateRatewhichwhich isis thethe raterate ofof heatheat inputinput (kJ/s)(kJ/s) requiredrequired toto produceproduce unitunit shaftshaft outputoutput..

HeatHeat RateRate (H(H..RR..)) == Q₁Q₁ // WtWt –– WpWp == 11//ȠȠ;; kJ/kWkJ/kW ss

TheThe capacitycapacity ofof aa steamsteam powerpower plantplant isis oftenoften expressedexpressed inin termsterms ofof SteamSteamRateRate oror SpecificSpecific SteamSteam ConsumptionConsumption (S(S..SS..C)C)..

DefinedDefined asas thethe raterate ofof steamsteam flowflow (kg/s)(kg/s) requiredrequired toto produceproduce unitunit shaftshaftoutputoutput ((11 kW)kW)..

SteamSteam RateRate (S(S..RR..)) == 11//WnetWnet ;;kg/kWkg/kW ss

TheThe cyclecycle efficiencyefficiency isis sometimessometimes expressedexpressed alternativelyalternatively asas HeatHeat RateRatewhichwhich isis thethe raterate ofof heatheat inputinput (kJ/s)(kJ/s) requiredrequired toto produceproduce unitunit shaftshaft outputoutput..

HeatHeat RateRate (H(H..RR..)) == Q₁Q₁ // WtWt –– WpWp == 11//ȠȠ;; kJ/kWkJ/kW ss

Latent heat ofVaporization 5 - 6

Const. Pr. Heating

Heated 4 – 5 till it becomessaturated liquid

Latent heat ofVaporization 5 - 6

Sensible Heating

• As the pressure increases, the latent heat decreases and sothe heat absorbed in the evaporator decreases and thefraction of the total heat absorbed in the superheaterincreases.

• In high pressure boilers, more than 40% of the total heat isabsorbed in the superheaters.

• There is a physical limit to the amount of heat that water

can absorb in any state. As the amount of heat that is usedto raise the temperature of water before vaporization cantake place increases, the amount of latent heat used toaccomplish that vaporization decrease.

Pressure

• As the pressure increases, the latent heat decreases and sothe heat absorbed in the evaporator decreases and thefraction of the total heat absorbed in the superheaterincreases.

• In high pressure boilers, more than 40% of the total heat isabsorbed in the superheaters.

• There is a physical limit to the amount of heat that water

can absorb in any state. As the amount of heat that is usedto raise the temperature of water before vaporization cantake place increases, the amount of latent heat used toaccomplish that vaporization decrease.

Latent Heat

• The total heat of the steam increases with the system pressure up toapproximately 30 bar.

• Thereafter, the total heat decreases with increasing pressure.• As the steam system approaches the critical pressure, little expansion can

take place.• The specific volume of steam decreases as the system pressure increases.• At atmospheric pressure a pound (0.4535 kg) of steam occupies about

1,600 times the volume of a pound of condensate.• As pressure increases in the system, the specific volume of the steam

decreases.• Because of this principle, a greater quantity of steam is available in a

smaller space (pipe, heat exchanger) at higher pressures.• This is why steam is often distributed at higher pressure but is reduced to

a lower pressure to perform specific heat-transfer functions.

• The total heat of the steam increases with the system pressure up toapproximately 30 bar.

• Thereafter, the total heat decreases with increasing pressure.• As the steam system approaches the critical pressure, little expansion can

take place.• The specific volume of steam decreases as the system pressure increases.• At atmospheric pressure a pound (0.4535 kg) of steam occupies about

1,600 times the volume of a pound of condensate.• As pressure increases in the system, the specific volume of the steam

decreases.• Because of this principle, a greater quantity of steam is available in a

smaller space (pipe, heat exchanger) at higher pressures.• This is why steam is often distributed at higher pressure but is reduced to

a lower pressure to perform specific heat-transfer functions.

• Rising pressure constrains the molecules from moving apart when water vaporizes.At the critical pressure of 221 bar, the specific volumes of liquid and gas are equal.

• Differences in density are generally referred to by the measurement of specificvolume. As pressure increases in the system, the specific volume of the liquid risesmarginally.

Water is incompressible, and therefore is not affected by steam pressure. Aspressure increases, however, so does the steam temperature. This temperatureincrease results in greater motion in the molecules of the water and a slightincrease in its specific volume.

• Rising pressure constrains the molecules from moving apart when water vaporizes.At the critical pressure of 221 bar, the specific volumes of liquid and gas are equal.

• Differences in density are generally referred to by the measurement of specificvolume. As pressure increases in the system, the specific volume of the liquid risesmarginally.

Water is incompressible, and therefore is not affected by steam pressure. Aspressure increases, however, so does the steam temperature. This temperatureincrease results in greater motion in the molecules of the water and a slightincrease in its specific volume.

Improving Rankine CycleImproving Rankine CycleImproving Rankine CycleImproving Rankine Cycle

The efficiency of the steam turbine will be limited by water dropletformation. As water condenses, water droplets hit the turbine blades athigh speed, causing ‘’pitting & erosion’’, and so, gradually decreasing thelife and efficiency of the turbine.

In order to avoid above disadvantages and improve cycle efficiency, thefollowings are to be used wherever possible :

LoweringLowering thethe CondenserCondenser PressurePressure

IncreasingIncreasing thethe BoilerBoiler PressurePressure

CycleCycle withwith SuperheatSuperheat

CycleCycle withwith ReheatReheat

CycleCycle withwith RegenerationRegeneration

The efficiency of the steam turbine will be limited by water dropletformation. As water condenses, water droplets hit the turbine blades athigh speed, causing ‘’pitting & erosion’’, and so, gradually decreasing thelife and efficiency of the turbine.

In order to avoid above disadvantages and improve cycle efficiency, thefollowings are to be used wherever possible :

LoweringLowering thethe CondenserCondenser PressurePressure

IncreasingIncreasing thethe BoilerBoiler PressurePressure

CycleCycle withwith SuperheatSuperheat

CycleCycle withwith ReheatReheat

CycleCycle withwith RegenerationRegeneration


Mean Temperature of Heat AdditionMean Temperature of Heat Addition

ηrankine = 1 – T₂/ TmLowering the condenser pressure, Higher will be theefficiency of Rankine cycle.

Higher the mean temperature higher will be the cycle efficiencyHigher the mean temperature higher will be the cycle efficiency

We can improve the efficiency of a Rankinepower cycle by increasing the pressure of theboiler and by decreasing the pressure of thecondenser.

Lowering the operating pressure of thecondenser lowers the temperature at whichheat is rejected. The overall effect of loweringthe condenser pressure is an increase in thethermal efficiency of the cycle.







Increasing the Boiler PressureIncreasing the Boiler Pressure

Increasing the operating pressure of theboiler, automatically raises thetemperature at which boiling takesplace.

This raises the average temperature atwhich heat is added to the steam andthus raises the thermal efficiency of thecycle.







Effect of SuperheatingEffect of Superheating

The average temperature at which heat isadded to the steam can be increased withoutincreasing the boiler pressure by superheatingthe steam to high temperatures.

Superheating the steam to highertemperatures has another very desirableeffect: It decreases the moisture content of thesteam at the turbine exit.







Reheat CycleReheat Cycle

1. Increases thermal efficiency

2.Increases dryness fraction of the steam atturbine exhaust, this will reduce blade erosion.

3.Increase work done per unit mass ofsteam, thus reducing boiler size.

4. Increases plant cost due to re-heaterrequirement and it’s long piping system.

5.Increases condenser capacity due to theincrease in steam dryness fraction.
















Regenerative CycleRegenerative Cycle

The regenerative Rankine cycle is so named becauseafter emerging from the condenser, water is heatedby steam tapped from the hot portion of the cycle.

Direct contact heating: The fluid at 2 is mixed with thefluid at 6 (both at the same pressure) to end up with thesaturated liquid at 3

Bleed steam from turbine between stages and sentto feedwater heaters to preheat the water on its wayfrom the condenser to the boiler. These heaters do notmix the input steam and condensate, function as anordinary tubular heat exchanger, and are named "closedfeedwater heaters".










Effect of Inlet PressureEffect of Inlet PressureEffect of Inlet PressureEffect of Inlet Pressure

Superheaters, Valves, Pipelines, inlet stages of the turbine are subjected to highpressure and temperatures due to metallurgical limit.

The maximum temperature is fixed by this limit , as the operating steam pressure atwhich the heat is added to the boiler increases from p1 to p2, the mean temperatureof heat addition increases.


Effect of Variation of Steam Condition on Thermal Efficiency ofEffect of Variation of Steam Condition on Thermal Efficiency ofSteam Power PlantSteam Power Plant

Effect of Variation of Steam Condition on Thermal Efficiency ofEffect of Variation of Steam Condition on Thermal Efficiency ofSteam Power PlantSteam Power Plant

For inlet steam pressure above 100 bar, there is continuous but decreasing rate ofimprovement of cycle efficiency.

Increase in the steam pressure is limited by considerations of mechanical stresses andhigher cost of equipment.

Considerable improvement in the cycle efficiency with decrease of condenserpressure. Depends on the temperature of cooling water.

Less in warm region and more in cold region.


For inlet steam pressure above 100 bar, there is continuous but decreasing rate ofimprovement of cycle efficiency.

Increase in the steam pressure is limited by considerations of mechanical stresses andhigher cost of equipment.

Considerable improvement in the cycle efficiency with decrease of condenserpressure. Depends on the temperature of cooling water.

Less in warm region and more in cold region.

Rankine Cycle in a Power PlantRankine Cycle in a Power PlantRankine Cycle in a Power PlantRankine Cycle in a Power Plant


Power Plant CyclePower Plant Cycle

Combined CycleCombined Cycle

Analysis of Steam Cycles

Engineering

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