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Until recently, gas turbines were manufactured
with an expected operating time between overhauls
of typically 8,000 hours when operating on a gas
fuel. Utilizing the latest technology, plant users
expect the most efficient performance levels available
on the market. However, the addition of certain
new or upgraded components to older equipment
can bring attractive gains in terms of improved
availability, improved fuel economy and increased
power output.
With regard to availability, MJB International
has introduced a programme to greatly improve
the durability of combustion system components.
This programme improves cost effectiveness of
gas turbine operation by increasing combustion
inspection intervals by up to 16,000 hours, and
consequently leading to improved availability.
The Problem
Stress, wear and creep growth are very common
problems with the following consequences:
- Thermal stresses leading to cracking
of critical components
- Excessive wear due to vibration caused
by the combustion dynamics
- Creep growth in areas such as the transition
piece picture frames, which leads to distortion
and incorrect power distribution in the
critical gas path
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The Solution
By the application of thermal barrier coatings,
local "hot spotting" of the parent materials is
reduced, as is the thermal stress, thus preventing
cracking of critical components. By applying hard-face
coatings and wear resistant materials, and by
reducing clearances, wear due to vibration is
minimized.
The Benefits
By employing the latest technology in this way:
- Availability is increased by reducing
the number of overhauls
- Spare parts requirements are reduced
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All of which allow the power station managers
to achieve their objective of increasing the overall
profitability of their plant.
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