Kalina Cycle

7/30/2019 Kalina Cycle

1/31

Power Generation Using Multi Component

Working Fluids

P M V Subbarao

Professor

Mechanical Engineering Department

Indian Institute of Technology Delhi

Synthesis of More Appropriate Working Fluids


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Irreversible Heat transfer process : Rankine Cycle

S

1

33

5

7

6

8 1kg

T

Flue gases

Cooling water

s

External Irreversibilities with Rankine cycle

e

f

2

1

4

5

6

C

A

External

Irreversibility-1

External

Irreversibility-2

Steam


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3

34.520

0.057M

7.135

KCAL/KG

34.700

735.8

683.2

15.87

61.067 424.534.700 3

09.4

200.0

639.314

HEAT RATE=1985.05 K CAL/KW

Radiation losses are Ignored

210.3

206.0

639.3

14

61.067

256.21

0.000M

247.0

6.0K

0.0K

D

38.54

205.5

170.0

172.0

509.0

26

124.0

6.414

639.31495.766

T/HR CEL

162.1

160.7

205.5

639.314

6.0K

0.0K

168.3

164.1

120.8

121.3

34.520

6.564

26.299

2.269

2.8K

195.5

740.70352.2

2.154

M

0.024

M

0.935

M

2.186

M

740.70

352.2

6

1.067

4

0.57

740.7

0

350.4

40.57

572.218

14.970 M

639.314

816.06

537.0

ABC

150.0

A

1.251

M

0.701

M

0.018

M

0.043

M

0.946

M

537.0

843.89

789.916.70789.9

423.0

572.156

36.52

CB C B

4.352 M

777.2 H

B

A

0.4361 619.864.846 M

D

C

123.8

95.0

95.0

76.2

76.3

58.8

509.026

92.4

509.026 92.2

26.299

43.183

72.7

72.6

63.693

63.693

58.8

3.7K

0.8616

16.883

2.8K

106.8

642.9

0.4143

20.510

619.8

76.

5

509.028

509.028

D

77.96

49.2

49.0

20.510

47.0

0.299M

46.8

99.9

99.9

0.299

46.3

46.7

46.446.1

509.028

D

12.0K

509.0280.1033

19.38748.8H

0382M

0.078M

16.833

0.9069

26.299

2.389 683.2

195.8

310.0

735.8

642.9

107.1

310.0

735.8

506.53

7.135

C B C

0.382

0.078

577.3

P=210.061 MW

46.45441.114

0.1033

3.068 M B

0.854 MD

G

B

C

Fig.1.4 Layout of 210MW Coal Fired Power Plant

Low pressure and low temperature region

Fig 2 Layout of modern Coal fired power plant

Working fluid waterBest performance at high pressure

Heat and mass balance program

Optimal bleed pressure &


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4

Location of condensation process in a Low pressure steam turbine

(Source Alstom )

Exit at higher

velocity

Kinetic

Energy

loss

MoistureLoss

0.3783 m3/ kg

12.65 m3/ kg


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Erosion of a long last stage blade

( Source Alstom )

For example, a long, full speed rotor blade,operating in a non-reheat cycle, may

involve wetness levels of about 15% at

exhaust.

Without suitable counter-measures this can

result in extreme tip-erosion (illustrated in

Fig).


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Source of Energy Vs Working Fluid

The overall efficiency of a thermodynamic conversion

cycle is a consequence of ;

the energy potential of the source-sink combination, of

internal inefficiencies (losses in turning machinery, in

regenerators,etc.) and

of losses from irreversible heat transfer from a source

and to a sink.

The latter depends mostly on the levels of matching of

the apparent heat capacities of the working fluid, source

and sink.


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In principle, a divergence in the thermal behaviour

between a working fluid and a source or sink can be

counteracted by using complex cycle configurations such

as evaporation at multiple pressure levels in modern

combined cycles or condensation at 2 or 3 decreasingtemperatures in cogenerative systems.


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Energy Recovery from Hot Gas

Two Phase Fluid

300

250

200

150

100

50

T 0C


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T-S and T-X DIAGRAMS : Binary Components


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The condenser pressure can be much higher in two componentfluid cycle, and the cooling water temperatures do not impact

the power output of the turbine . Thermo-physical properties of mixture can also be altered by

changing the concentration of one component.

This helps to recuperate or regenerate energy in the

condensation system. Modifications to the condensing system are also possible by

varying the mixture concentration and thus more energy can berecovered from the exhaust gases.

Expansion in turbine can give a saturated vapor in two

component fluid cycle compared to wet steam. Conventional equipment such as steam turbines can be used in

two component fluid cycle.


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Brief History

The technology is the creation of Dr. Alexander Kalina, a

Russian scientist.

He left a high position in Soviet Union 30 years ago to

come to US.

Formed Exergy Inc. to develop and commercialize anadvanced Thermodynamic Cycle.

1993, General Electric signed an agreement with Exergy

for a world wide exclusive licensing rights to use the

technology for combined cycle systems in 50 MW to 150

MW range.

GE and Exergy working on a combined cycle plant that

will operate on an overall efficiency of 62%.


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Simple Kalina CycleThe pump pressurized the saturated liquid (5)

which is leaving from the condenser and it is

sent in to the high temperature recuperator (6).

The liquid takes off the heat from the two phasedead vapour (3).

The pressurized hot liquid (sub-cooled state)

enters (1) into the vaporizer where the liquid is

converted in to vapor (2) by utilizing the latent

or sensible heat of the hot source (1s-2s).

The saturated vapor (2) from the vaporizer is

expanded in the turbine up to its condenser

pressure.

The two phase mixture after giving a part of

its latent heat to the incoming liquid (4) enters

in to the condenser, where cooling water enters

(1w), takes away all the heat available in the

two-phase mixture, and leaves at higher

temperature (2w).

The saturated liquid is pressurized in the pump

and the cycle repeats.


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T-S and T-X DIAGRAMS


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Ammonia water cycle modeling

The mathematical models for Ammonia water cycle are

constructed using the theory of thermodynamics.

The whole system is divided into many components namely

vaporizer, steam turbine, condenser, high temperature

recuperator etc.

According to the characteristic construction of each

component, appropriate assumptions are introduced.

Steady State Steady Flow Models are developed.


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Vaporizer


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Optimization

In this case, efficiency of the cycle is considered as the objective function to be

optimized.

The Ammonia water cycle has four variables.

Fraction of ammonia (x)

Turbine inlet pressure (P3)

Heat source inlet temperature T1S

Heat source outlet temperature T3S.

The cycle performance depends on the values for these four variables that are

free to change during optimization.

Each combination of the eight values represents a unique operating condition of

the cycle.

Searching for optimum values for these variables are the task of this

optimization work.

Consequently, the objective function to be maximized can be written as,


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Variation of first law efficiency at different steam inlet conditions of simple

Saturation Pressure of Rankine Cycle (bar)


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Modern Kalina Cycle


27/31

Effect of variation in fraction of ammonia at the evaporator inlet on

first law efficiency

The following modifications are suggested for the proposed Ammonia water

cycle when compared to KCS 34.

1.Super heater is added in the cycle to utilize the superheated steam at low

temperature and pressure.

The saturated vapor from the separator is superheated in the super heaterbefore entering the steam turbine.

2.The additional feed water is included in the system, which utilize the

sensible heat of low grade to heat the sub-cooled water coming it from the

condenser of an Ammonia water cycle


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Kalina Cycle with Subcooler


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The Superheat Kalina Cycle


31/31

Comparison of Exergy destruction in various

components of the Ammonia water cycles

Documents

Kalina Cycle