Higher power production with reduced
downtime is a major challenge in most power plants. Thermal spray technologies
for example arc wire spray are commonly used in the power production repair
units. The electric arc spray wire process offers economical and
possible coating options that encourage affordability and reliability of power
production units that run with maximum capacity for several months.
Thermal spray coatings increase service
time and life of a boiler steam based power units. Production water wall tubes
and super heater banks that experience attacks of sulfuric and vanadium gases
in coal-fired boilers, get extensive increase in their service when sprayed
with coatings. When application requirements allow the use of electric arc
spray process, the coating significantly increase the service life. Arc sprayed
materials are widely in use in global boiler applications including high
chromium based nickel alloy for longer life of coal based boiler tubes and
Iron-Chromium alloy that has very high hardness is fit for the coal fired
boiler condition and a matrix nanocomposite material is used in flu gas
component of the boiler.
Introduction and application of thermal
spray techniques is fully accepted for service in main tube components of
boilers. A venture to extend these benefits to critical systems is now under
analysis. By increasing the scope of thermal spray applications, the overall
lifecycle of the whole boiler can be enhanced. Boiler systems are made from fly
ash handling unit, induced draft fan and fuel handling unit.
Various solid fuels are used in power units
such as coal. Considering the alternatives to fossil fuels, wood and trash fuel
sources are receiving increased popularity. The main trouble with solid fuels
such as coal, wood or trash is the large magnitude of particulates that carry
flue gas path from the fire box to the exiting stack, causing wide erosion of
several components. This factor of the process causes more complications.
A crucial ask in power production facility
is to keep up environmental discharges at ideal limits. An example of this
emission factor is opacity limit- magnitude of particulate matter that travels
through the whole flu path and is released into the atmosphere through smoke
stacks. To maintain the opacity level in a specific essential level and reuse
as potential energy from the fuel source as feasible , fly ash is re-sent back
in the boil before to the induced draft fans through a classifier that
separates the exiting char. The re-supplied char moves back to the warmest area
of the furnace and moves through the remaining flue gas before it is fully
burned to a size beyond the limit of classifier and into the exiting
particulate scrubber unit before leading to plant’s exit point.
In wood fire units the resupplied char is
very abrasive. It can adversely affect classifier components and cut deep
grooves in the re-injection pipes, creating poor flow that causes beyond the acceptable
limits of opacity discharge. Users of thermal spray technology in boiler repair
field encourages the applications in addition of coating the boiler tubes to
increase the life of power production systems.
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