Development of Steam & Gas Turbines

P M V SubbaraoProfessor

Mechanical Engineering Department

Basic Elements of Industrial Revolution……

Steam Vs Gas Turbines

Steam Turbine Gas Turbine

External Combustion Internal Combustion

Works at the mercy of Heat Transfer No impact of Heat Transfer

Heavy infrastructure Light infrastructure

Working fluid is recycled Working fluid is refreshed

Working fluid behaves cleverly and suitably changes its phase

Remains gaseous.

Very low internal consumption of work. Huge internal consumption of work.

Relative more efficient Relatively pure efficiency.

Best suited for Stationary Power Packs Best suited for Mobile Stations

Historical Debate : Steam Turbine Vs Gas Turbine

• Experience gained from a large number of exhaust-gas turbines for diesel engines, a temp. of 538°C was considered absolutely safe for uncooled heat resisting steel turbine blades.

• This would result in obtainable outputs of 2000-8000 KW with compressor turbine efficiencies of 73-75%, and an overall cycle efficiency of 17-18%.

• First Gas turbine electro locomotive 2500 HP ordered from BBC by Swiss Federal Railways

• The advent of high pressure and temperature steam turbine with regenerative heating of the condensate and air pre-heating, resulted in coupling efficiencies of approx. 25%.

• The gas turbine having been considered competitive with steam turbine plant of 18% which was considered not quite satisfactory.

• The Gas turbine was unable to compete with “modern” base load steam turbines of 25% efficiency.

• There was a continuous development in steam power plant which led to increase of Power Generation Efficiencies of 35%+

• This hard reality required consideration of a different application for the gas turbine.

First turbojet-powered aircraft – Ohain’s engine on He 178

The world’s first aircraft to fly purely on turbojet power, the Heinkel He 178.

Its first true flight was on 27 August, 1939.

Rankine Cycle for Nuclear Power Plant

Rankine Cycle for Geothermal Power Plant

Ranking Cycle for Solar Thermal Power Plant

Ranking Cycle for Biomass Thermal Power Plant

How to select the Principle of Torque Creation ?

Impact of Cycle Thermodynamics …..

Constant Pressure Steam Generation Process

W J M Rankine ~ 1860

Constant Pressure Steam Generation: vdpdhq =0

Theory of flowing Steam Generation

vdpdhq

qHVm fuelSG

Knowledge for Use & Design

Constant Pressure Steam Generation: dhHVm fuelSG

Practical way of understanding the utilization of fuel energy:

dTcHVm pfuelSG

Is it possible to get high temperature with same amount of burnt fuel?

What decides the maximum possible increase for same amount of burnt fuel?

Knowledge for Conservation

dss

hTdsq

p

constant

constantps

hT

Creation of Temperature at constant pressure :

TdsdhqHVmpfuelSG

Steam Generation : Expenditure Vs Wastage

h

s

Liquid

Liquid +Vapour

Vapour

Variable Pressure Steam Gneration

s

h

Increase in Specific

Increase in Specific Specific

Pressure Enthalpy Entropy Temp VolumeMPa kJ/kg kJ/kg/K C m3/kg

1 1 3500 7.79 509.9 0.35882 5 3500 7.06 528.4 0.071493 10 3500 6.755 549.6 0.035624 15 3500 6.582 569 0.023695 20 3500 6.461 586.7 0.017766 25 3500 6.37 602.9 0.014227 30 3500 6.297 617.7 0.011878 35 3500 6.235 631.3 0.0102

Analysis of Steam Generation at Various Pressures

More Availability of Energy

Specific Specific Specific

Temp Pressure Volume Enthalpy EntropyC MPa m3/kg kJ/kg kJ/kg/K

575 5 0.0762 3608 7.191575 10 0.03701 3563 6.831575 12.5 0.02917 3540 6.707575 15 0.02393 3516 6.601575 17.5 0.02019 3492 6.507575 20 0.01738 3467 6.422575 22.5 0.0152 3441 6.344575 25 0.01345 3415 6.271575 30 0.01083 3362 6.138575 35 0.008957 3307 6.015

Behavior of Vapour At Increasing Pressures

ps

hT

constp

.

All these show that the sensitivity of the fluid increases with increasing pressure.

T

v

p

s

constT

.

T

v

p

s

constT

.

s

MPap,

Creation/Reduction of Wastage

Less Fuel for Creation of Same Temperature

MPap,

kgkJh,

Availability of Steam for Condenser Temperature of 450C

Turbine Inlet : 3500 kJ/kg Turbine Exit

Specific Specific Specific Available

Pressure Entropy Temp Volume Enthalpy Quality Work

MPa kJ/kg/K C m3/kg kJ/kg kJ/kg

1 1 7.79 509.9 0.3588 2464 0.9502 1036

2 5 7.06 528.4 0.07149 2232 0.8532 1268

3 10 6.755 549.6 0.03562 2135 0.8127 1365

4 15 6.582 569 0.02369 2080 0.7897 1420

5 20 6.461 586.7 0.01776 2041 0.7736 1459

6 25 6.37 602.9 0.01422 2012 0.7615 1488

7 30 6.297 617.7 0.01187 1989 0.7518 1511

8 35 6.235 631.3 0.0102 1969 0.7436 1531

Progress in Rankine Cycle

Year 1907 1919 1938 1950 1958 1959 1966 1973 1975

MW 5 20 30 60 120 200 500 660 1300

p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 15.9 24.1

Th oC 260 316 454 482 538 566 566 565 538

Tr oC -- -- -- -- 538 538 566 565 538

FHW -- 2 3 4 6 6 7 8 8

Pc,kPa 13.5 5.1 4.5 3.4 3.7 3.7 4.4 5.4 5.1

,% -- ~17 27.6 30.5 35.6 37.5 39.8 39.5 40

Steam Path in Modern Turbines

Steam Conditions : Recent Installations of The World

Advanced 700 8C Pulverised Coal-fired Power Plant Project