Device 1. Electric Motor =2. Home Oil Furnace = 3. Home Coal Furnace =4. Steam Boiler (power plant) =5. Power Plant (thermal) =6. Automobile Engine =

Efficiency(%)

90

65

55

8936

25

A coal-fired thermal power station.

1. Cooling tower. 6. Boiler drum2. Electric generator (3-phase). 7. Superheater3. Condensor. 8. Economiser 4. High pressure turbine. 9. Air preheater 5. Feed heater 10. Chimney Stack.

CRITICAL CONDITION IS THERMODYNAMIC

EXPRESSION DESCRIBING THE STATE OF A

SUBSTANCE BEYOND WHICH THERE IS NO

CLEAR DISTINCTION BETWEEN THE LIQUID

AND GASEOUS PHASE

DEFINITION OF CRITICAL CONDITION

WHAT IS SUPERCRITICAL PLANT

The power plant which operates above the critical condition is a ”SUPER CRITICAL POWER PLANT

Water reaches to this state at a critical pressure above 22.1 MPa and 374 oC.

Rankine Cycle Supercritical Unit

8

1 - 2 > CEP work

2 – 2s > Regeneration

2s - 3 > Boiler Superheating

3 – 4 > HPT expansion

4 – 5 > Reheating

5 – 6 > IPT & LPT Expansion

6 – 1 > Condenser Heat

rejection

This advanced technology for power generation

Higher Efficiency, Clean, Safe Overall Environment

The development of coal fired supercritical power plant technology can be described as an evolutionary advancement towards greater power output per unit and higher efficiency.

Sub-Critical vs Super CriticalSub-Critical vs Super Critical

Description Sub Critical Super Critical

Full Load Pressure <190 atm >240 atm

Flow in Water wall 2-Phase 1-Phase

Cycle efficiency Base + 2 - 3 % Approx

Fuel saving Base +8 - 10 % Approx

Boiler weight Base + 10 %

Stages of reheat 1 2 Preferred

Supercritical power plants are highly efficient plants with best available pollution control technology, Reduces existing pollution levels by burning less coal per megawatt-hour produced, capturing the vast majority of the pollutants. Increases the kWh produced per kg of coal burned, with fewer emissions.

WHY ADVANCED SUPERCRITICAL

• Efficiency of the Rankine Cycleincreases with increasing Turbine inletTemperature and Pressure

• Cycle efficiency of typical sub-criticalplant is 38% whereas today’ssupercritical technology increases thisto around 45-47%

Coal-fired Supercritical Power plants operate at very high temperature [580°C temp.] & with a pressure of 23 MPa)

Resulting much higher heat efficiencies (46%), as compare to Sub-Critical coal-fired plants.

Sub-Critical coal-fired plant operates at 455°C temp., and efficiency of within 40%.

Supercritical & Ultra-Supercritical Power Plants

BENIFITS: High Thermal Efficiency Environment Friendly Lower fuel cost per unit of power Run-of-Mine Coal can be directly used

Weaknesses: Materials Limitation High levels of corrosion Increased supervision and maintenance

costs Limited scope for retrofitting

opportunities

Supercritical & Ultra-Supercritical Power Plants

CONCLUSION The current state-of-the-art for coal-fired supercritical

steam cycles is –600C/300 bar maximum steam conditions, with a net thermal efficiency of about 45% (LHV, based on UK inland conditions). 620C plant are expected within five years while, in the longer term (10-20 years). 650-700C is expected, with resulting cycle efficiencies in the range 50-55%.

Materials limitations are the major factors limiting further development, with key constraints at the furnace wall, superheater and reheater outlets, and the first stages of the HP and IP turbines. Considerable materials R&D is under way in Europe, Japan and the USA.

Thank you for your Attention