The document discusses technologies for improving gas turbine efficiency through higher operating temperatures. It covers new high-temperature materials like superalloys and ceramics that allow increasing the combustion temperature. It also discusses manufacturing techniques like directional solidification and single crystal growth that enhance material properties. Combined cycle power plants are highlighted as a way to further increase efficiency by capturing waste heat. Challenges of using syngas from gasification as a fuel are also summarized.

1. Advancement in
Turbine Technology
Team Global

2. The important point of turbine system is turbine expansion process
(working fluid’s high T energy gas is converted into mechanical
energy to drive the compressor and the electric generator).
One of the ways to increase the efficiency of turbine expansion
process is raising the temperature. But there has limit to maintain the
materials shape of turbine system.
So, we need to improve an effective thermal barrier to shield the spar
from the hot combustion gases.
How we enhance the strength of materials of turbine? We associated
the way to enhance the strength of materials with process of
materials in material science and engineering.

3. New Materials
Materials with High Thermal Resistance

4. Types of high temperature materials for gas turbines
Ni-base Super Alloys
Used for high temperature components
Single Crystal Super Alloys
High temperature capabilities
Third-generation SC Alloys
Increase inlet gas temperature to increase thermal efficiency (in land-based gas turbines)
Fourth-generation SC Alloys
With platinum group metals; next generation Jet engines

5. New Materials
Oxide Dispersion-strengthened Super Alloys
Excellent creep strengths at high temperature, ultra-high thermal efficiency
Intermetallic Alloys
Disadvantage: poor room-temperature ductility
e.g.: Ti-Al alloy: light weight and high specific strength, certain level room-temperature ductility
Refractory Alloys
High melting points (uncooled turbine blades)
Platinum-group Metals based Refractory Super Alloys:
“refractory super alloys” composed of the γ / γ’ structure observed in Ni-base super alloys in Platinum
group metals with high melting points

6. New Materials
Ceramics
Long creep rupture life at high temperature, high toughness, long-time oxidation & corrosion resistance
At extremely low temperature, some ceramics exhibit superconductivity
E.g. Silicon Nitride (Si3N4)
Composite Materials
Ceramic matrix composites (CMC): great fracture resistance ,lightweight, can tolerate ultra-high
temperatures
(excellent candidates for combustor liners, high-pressure turbine vanes and shrouds)
Ceramic fiber reinforced ceramic (CFRC) material: elongation to rupture up to 1%, strongly increased
fracture toughness, extreme thermal shock resistance, improved dynamical load capability,
anisotropic properties following the orientation of fibers

7. New Materials
Composite Materials
Carbon-Carbon (C/C) composites: lightweight, high strength at high temperature
Notes:
• It is essential to improve the properties of high temperature
materials so that higher inlet gas temperatures can be
reached.
• Ni-base super alloys will be playing a major role in near
future although new materials are being materialized.

8. Processing of Materials
Manufacturing Processes to Maximize Resistance

9. Heat treatment techniques
Heat treatment involves the use of heating or chilling, normally to extreme
temperatures, to achieve a desired result such as hardening or softening of a
material. Heat treatment techniques include annealing, case hardening,
precipitation strengthening, tempering and quenching.
There are many purposes of heat treatment.
•
Improving resistance to strength and tensile force (Tempering)
•
Making grains finer and less directional (Normalizing)
•
Stabilization and homogenization of structure (Annealing)
•
Improvement of surface strength (Surface Hardening)
and so on...

10. Directional solidification
Directional and progressive solidification describe types of solidifications within castings.
Directional solidification occurs from farthest end of the casting and works its way towards
the sprue. Progressive (or Parallel) solidification starts at the walls of the casting and
progresses perpendicularly from that surface.
Having many grains at high temperature
reduces material property because of grain
boundary sliding. Grain boundary sliding
also creates surface cracks. Directional
solidification technique enhances properties
of the materials at high temperature by
avoiding grain boundary sliding. Directional
solidification also helps to match to alloy
composition by reducing creep strength of
certain super alloys.
Note: The [100] growth direction offers the best overall mechanical properties.

11. Single crystal solids
A single crystal or monocrystalline solid
is a material in which the crystal lattice
of the entire sample is continuous and
unbroken to the edges of the sample,
with no grain boundaries. The absence
of the defects associated with grain
boundaries can give monocrystals
unique properties, particularly
mechanical, which can also be
anisotropic depending on the type of
crystallographic structure.
Single crystals has no grain boundaries so
they are expected to endure high
temperatures. But it is difficult to
manufacture single crystals in the shape of
a blade so we need to study about casting.

12. Design and Testing
Configurations and Component
Testing Methods

13. Focus
Power plants today focus mainly on the
Cost Efficient Production of Energy.
Imposes requirements of:
•
Low overall life cycle costs
•
High reliability and availability
•
Operating flexibility

14. Types of Power Plants
Steam Power Plants (SPP)
Standard steam power plants.
Operated at sub-critical conditions.
These have efficiencies of about
30-35%

15. Types of Power Plants
Combined Cycle Power
Plants (CCPP)
A combined cycle is an
assembly of heat engines
that work in tandem from
the same source of heat,
converting it into
mechanical energy, which
in turn usually drives
electrical generators.
Principle:
Exhaust of one heat
engine is used as the heat
source for another, thus
extracting more useful
energy from the heat,
increasing the system's
overall efficiency.

16. Example: Integrated Gasification Combined Cycle (IGCC)
The waste heat
produced from the
reaction to create
the syngas is then
recovered to create
steam that is used
to drive a steam
turbine
creating
more electricity.
Source: http://www.instructables.com/id/Top-Tips-for-a-Power-Station-to-increase-its-effic/step4/Integrated-Gasification-Combined-Cycle-IGCC/

17. Improving Efficiency
Technologies that can be used to increase efficiency:
Fluidised Bed Combustion
Supercritical & Ultra supercritical Technology
Integrated Gasification Technology
Advantage: If implemented across all power plants
up to 25% reduction in C02 emissions from coal
which would equate to a
6% reduction in global CO2 emissions.

18. Fluidised Bed Combustion
The process of fluidised
bed combustion involves
suspending solid fuels in
upwards jets of air during
the combustion process.
The advantage that FBC
has is it makes it easier to
burn fuels that are hard
to ignite such as coal
mine
wastes
and
petroleum coke.
Source: http://www.instructables.com/id/Top-Tips-for-a-Power-Station-to-increase-its-effic/step3/Fluidised-Bed-Combustion-FBC/

19. Supercritical & Ultra-supercritical Technology
Supercritical Steam
Generator
Ultra-supercritical
In contrast to a "subcritical
boiler", a operates at such a high
pressure (over 22 MPa) that
actual boiling ceases to occur,
the boiler has no liquid water steam separation.
Steam temperatures above
600 degrees Celsius and
pressures around 27 MPa.
Efficiency
Efficiency
42-46%
45-48%

20. Testing
Laboratory testing
• Destructive
• Non-destructive:
ultrasonic, liquid
penetrant, magnetic
particle and X-ray
examination (For critical
rotating components)
Field testing
Example: Rainbow tests
Materials for evaluation are
installed in customers’
machines for side-by-side
comparison with current
baseline material.

21. Syngas as a Fuel
High Temperature Combustion

22. The fuel gas generated by gasification of coal consists primarily of H2 and CO, along
with smaller amounts of CH2 and higher-order hydrocarbons, CO2 , and H2O;
The level of N2 in syngas can vary from low to high,
depending on whether the gasifier is oxygen- or air-blown.
Advantages:
High Temperature Combustion (700 degrees)Higher Efficiency
Renewable Source (if biomass is used)
Reduced or even zero emissions coupling of a gas turbine
combined-cycle system with coal gasification

23. Major Challenges
• CV of syngas = 1/3 of natural gas;
CV of hydrogen = 0.3 times that of methane
Leads to differences in the relative gas flows in the turbine when compared on
the basis of constant power; implications for combustor design, flame stability
and increased heat transfer to the combustor can and airfoils.
• Need for better long-term data to characterize creep and fatigue
performance of materials as a basis for improved design and reliable
operation, as well as better definition of the actual conditions, especially
temperature and temperature range, experienced by the key components in
the hot gas path.

24. Major Challenges
• Syngas (and hydrogen) have significantly higher laminar flame speeds than
natural gas, giving rise to flame stability issues.
• High levels of water in changes heat transfer properties of the flame and
ability to maintain adequate cooling of key components; high water vapor
levels also may have detrimental effects on component durability.
• Greater corrosion potential based on its increased water vapor content, and
presence of alkali and sulfur levels near the maximum typically allowed.

25. Higher Efficiency
High Temperature
Fuel
Combustion at Higher
Temperatures
Materials with high
thermal resistance
Material Behavior for
Design
Better Coatings
Combined Cycle
Power Plants (CCPP)
Better cooling
techniques
Testing and Sensing
Techniques

26. Thank You