presentation draft me 2010 atlanta
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Fueling the Minds of Electricity
Marcus Evans 4th
annual Strategic Asset Management for
Power Plants
January 26th 28th
Introduction:
Existing market conditions call for
extra effort involving asset
management of our power plant fleet.
The standard for maintaining power
plant equipment is not the same as it
has been in years past. We do not
have the financial resources due to
budget restraints and the overall
termination of capital projects system
wide. In light of these current market
conditions, we are forced to do more
with less concerning our equipment.
The goal during these times is to use
our expertise and knowledge to
maintain our assets with limited resources. How do we reduce costs while increasing efficiency and
productivity? This workshop will highlight and discuss practical methods that will aid in streamlining
inspection and repair practices.
Changes in maintenance philosophy and the good old days:
If we thought it was tough to get funds
approved to perform maintenance in the
last 10 years, we would be astonished at
what we have to work with now. Utilities
are operating under staunch restrictions.
As a result, the conservative nature of
utility executives is shining through. At the
end of the day, all of us, the asset managers
are left holding the bag.
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Availability performance improvements pertaining to existing units traditionally, prior to current
market conditions:
Utilities have many opportunities to increase electrical output with existing units without increasing fuel
burn. This is achieved by improving efficiency or reducing forced outages through component
replacement and proper maintenance and performance improvements. In some cases, utilities do so asa reaction to unexpected component failures (reactive replacement). In others, utilities replace worn or
aging components that are expected to fail in the future or whose performance is deteriorating
(predictive replacement). In some cases, utilities replace components because more advanced designs
are available and would improve
operating characteristics at the
unit. Such component
replacement can restore a unit's
original design efficiency or, in
some cases, improve efficiency
beyond original design.
Historically, we just simply needed
to justify repairs by data and
component facts. Based off of
those findings, we could justify
funds. Now days its a little more
difficult, utilities are willing to
except greater EFOR and take
more risks when it comes to maintaining the equipment. Environmental impact plays a greater role
than equipment reliability and in some cases safety. Funds are being allocated to pollutant controls, andrenewable fuel source research, and less money is being allocated towards maintaining the actual
equipment that currently energizes our nation.
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Our nations craze for alternative energy sources and fuels has
depleted our efforts to work towards operating our existing
equipment and fuels to their cleanest, fullest potential. Of course,
we should always be looking for ways to improve the process and
operate more efficiently and cleanly. Having said all of this, during
unit operation with most fuels, there are pollutants that we must
battle against as an industry. Through chemistry we have found
ways to control certain emission such as NOx, SOx, Mercury etc,
but yet we still strive as a society to find continuous improvement.
The key here is to practice maintenance procedures that allow us
to operate reliably while controlling these types of pollutants.
Due to maintenance budget cuts etc, we are at risk of sacrificing
reliability due to emissions control equipment usage.
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Availability, reliability, and sustainability in a down economy:
With a reduction in electrical demand throughout the country we find ourselves in a paradigm shift.
Availability has taken a back seat to environmental, safety and economic considerations in running a
power plant. We need to be very cautious here as decisions made in these trying times can have asubstantial impact on our systems sustainability for decades to come. In more robust economic times
we have traditionally suggested availability improvement programs meant to restore the plants'
infrastructure to a level that restores the original reliability of the plants. Implementation of these
recommendations would allow the plants to increase generation output above recent historical output
without increasing gross generating capability.
Maintaining or restoring plants that are over 20 years old to a condition similar to plants that are under
20 years old can result in more reliable facilities that will be available to play an important role in
supporting the increasing strain on our electrical system's reserve margins and electrical demand
growth.
The U.S. electric generating system's reserve margins have declined dramatically over the last 20 years.
This situation has put pressure on the operators of our existing coal-fired fleet to restore, maintain, or
improve the reliability and availability of their facilities to keep pace with the growing demand for
electricity in the face of limited new capacity coming on line. The mandate for higher availability, lower
forced outage rates, and longer time spans between planned outages is more critical today than ever in
our history. But how do we accomplish these goals when we have fewer resources available?
The processes of discovery inspections followed by prioritization and execution of remediation have
proven to be effective historically. Unfortunately many in tough times cut the legs out from under the
discovery inspection portion of the program and expect the same outcome. If we restrict our ability togather information how can we make good decisions on where best to put our limited resources? So we
must maintain a vigorous and robust discovery inspection regime. This effort will provide our decision
makers with a full picture of the condition of the asset. By identifying the most critical problem areas
we can pin point with laser accuracy the monies we do have to spend. We also will have a clear picture
what our risks are going forward.
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Risk management:
Data Driven Planning
The challenges of successfully completing projects within an Operations and Maintenance environment
have increased over the last 10 years. In the Do More with Less" corporate environments,
maintenance staffs have experienced reductions in skilled staffing and budgets. Maintenance projectsare typically driven by unrealistic time constraints and typically delivered late. Both the operations and
maintenance staffs must find the right balance in planning and executing projects. Risk management is
the key to finding the acceptable balance within the project management methodology.
The typical application of the boiler outage project planning process, is to back fit the work flow or logic
into a given timeframe as developed by the boiler inspection scope of work, based on constraining
completion times for the project and with
consideration of resources constraints. The best
practices have the identification of risks (boiler
inspection results) beginning during a project selection
process or during the early planning process. These
risk events, if addressed, are identified as mostly
independent events when analyzed, and may have
several independent responses put in place. Due to the
project inspection team's lack of data or adequate
time, the responses usually consist of putting in place
contingencies of time and money.
While most repairs do not result in a loss of emissions
control, efficiency, performance issues are generally
not addressed when making Cost-based decisions.
While these effects are not directly related, the
secondary effects of disturbances in operation cause a
reduction in overall capacity and increased emissions. Conversely, by closely monitoring thermal
performance at the component level, O&M personnel can improve component reliability by spotting
problems early.
Utilities need to move from a "Cost-based" approach to asset management to a "Value-based"
approach.
The key difference between the two approaches is that the:
Value-based approach involves strategic decision-making that takes the long term affect of repairs into
account when making overhaul repair, replacement, and refurbish decisions.
Cost-based approach relied on available budget (can we afford it?) for maintenance decision-making
that often ignores equipment thermal performance and emissions considerations.
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Choice of Corrective /Preemptive Action:
Repeat tube failures can occur because a temporary rather than permanent
solution is applied to correct and/or prevent the tube failure problem. An
example of a temporary action is the use of sacrificial shields or
metal/plasma sprays to inhibit fire-side corrosion or erosion. A permanentsolution would be based on determining the respective root-cause, such as
a reducing atmosphere in the furnace, excessive flue gas velocity
respectively, and taking appropriate engineering and/or maintenance
preventive action. An example of a temporary action is the use of a window or pad weld to make a tube
leak repair. Best practice would be to immediately replace the damaged tube with a new tube section
(Dutchman), or to replace the window or pad welded section at the next scheduled boiler outage.
Unfortunately, many temporary solutions are not replaced with permanent action, and therefore fail
again within a short time interval.
All scheduled major boiler inspections should include boiler tube wall-thickness measurements in areas
experiencing erosion or corrosion damage, until erosion/corrosion rates are established. In areas
experiencing damage, root cause analysis will be performed and corrective, preventive, and control
actions taken to inhibit forced outages due to these mechanisms.
Problem Definition
Root-cause analysis of every tube failure is a prerequisite mandate for an effective formalized tube
failure prevention program. Before the actual root-cause of a boiler tube failure problem can be
determined, it is essential that the problem be clearly defined in terms of: the failure mechanism
Multidiscipline Approach
Activities associated with boiler tube failures, that is, mechanism
identification, root-cause analysis and verification, and appropriate
corrective and/or preventive action, are complex and usually
require the expertise of several technical/experience disciplines.
Examples could be: mechanism identification may require
knowledge of the metallurgical characteristics of boiler tube steels
at high temperature over time.
Permanent Engineered SolutionsIn many tube failure problems, temporary rather than permanent
engineered solutions are used to solve the problem, with the result that the remedy is a continuing and
costly maintenance burden. A good example might be where tubing is damaged by soot blower erosion
because the blower is located too close to a corner or wall protrusion, yet rather than relocate the soot
blower, the tubing is pad welded or shielded. In most cases, temporary repairs should only be used in
emergencies, with engineering fixes being the permanent solution.
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Operations personnel play a key role in heat rate and emissions
improvement and reliability at facilities where even small gains in
thermal efficiency provide big dividends in terms of improved
financial performance. A major point for plant management is to
recognize the importance of efficiency and availability awareness
among operators, and to make this awareness part of all operators
training. Including this awareness training in operator training is an
important part of any optimization effort. In order to identify
performance problems, the following are offered as inspection
points that can have an immediate impact on controllable heat
losses.
In some cases, emphasis on unit availability (stay running at all costs, regardless of short-term fuel
expenditures, material and labor costs) has been the paradigm for many plants. This is not to imply that
management was wasteful, but simply that the priority was on reliable delivery of power to the
customers, regardless of cost. This approach is easily justifiable because the general public demands andexpects the uninterrupted supply of electrical power. This approach spread across all segments of utility
business.
Training regimes of personnel:
It is essential that all inspection team members have formal
inspection technology training. Insufficient inspection training is
the primary contributing factor to instances of poor performance
of an inspection team. Having a background that well equips an
inspection team member for boiler inspection, in itself, is not
sufficient. This includes engineers, managers, welders, andmechanics; no one involved with the inspection process should
be exempt.
Quality initiatives: Initiatives such as Total Quality Management,
Quality Circles, benchmarking, etc., require basic training about
technology, quality concepts, guidelines and standards for quality, etc.
Safety:Safety training is critical where working with heavy equipment, hazardous chemicals, repetitive
activities, etc., but can also be useful with practical advice for avoiding problems.
y Increased job satisfactionand moraleamongemployeesy Increasedemployee motivationy Increasedefficienciesin processes,resultinginfinancialgainy Increasedcapacity to adoptnewtechnologiesand methodsy Increasedinnovationinstrategiesand productsy Reducedemployeeturnovery Enhancedcompany imagey Riskmanagement
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Certification:
Professional certification can be found in almost every industry in the United States today. Law,
construction, auto repair, nursing, accountancy, information technology training, aerobic instructing,
social work, engineering, software development, and association management just scratch the surface
of the wide range of professions that have voluntary or mandatory certification.
In our industry every employer has a general obligation to perform due diligence in ensuring the
competency of the personnel providing services at our facilities. Boiler Assessment certification provides
employers with evidence that the certificate holder has demonstrated a certain level of job-related
knowledge, skills and abilities. It provides a documented level of assurance that employees are
competent in safe work practices.
Certification provides concrete evidence that
the vendor is staffed with people who know
what they are doing and is competitive in any
comparison of quality of service.
All inspection and service personnel should
be qualified and certified by industry
standards to insure the quality of the
inspection outcome. Even though
certification programs have existed in the
past (ASNT, AWS) none of the previous
certification programs addressed the specific
needs of a power plant. A new organization
has been formed for this express purpose.
The American Association of Boiler Assessors
(AABA) has recently been launched. The
AABA will train, certify, and maintain a
registry of boiler professionals. This is a way
to increase quality and accountability of
Boiler Assessors working in your plants.
Certification demonstrates to governmental oversight, competitors, suppliers, staff and investors that
you use industry-respected best practices.
Certification helps you to demonstrate to shareholders that your business is run effectively. The process
of achieving and maintaining the certification also helps ensure that you are continually improving andrefining your activities. The regular assessment process will improve staff responsibility, commitment
and motivation. Certification can improve overall performance and remove uncertainty as to the quality
and experience of inspection personnel whether they be internal or external.
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Utilization of supplemental Boiler Inspection Team Members:
Intra Company
Personnel from other plants within your system are usually
team leaders or members of their respective plant boiler
inspection teams. This is a popular planned outage concept
as plants within the same system typically remove
equipment from service at different times. A wide range of
experience is enjoyed with such a compilation of talent;
however, their boilers and equipment may be of a different
model and manufacture. Additionally, management policy
may vary from plant to plant potentially confusing the relationship.
The team leader can address these problems by pairing the supplemental personnel with local boiler
inspection team members. Local paring of human resources ensures the policies and interests of the
subject plant are best served. Paring is also important in combining various levels of experience. Paring
experienced inspectors with trainees or lesser experienced inspectors promotes camaraderie and on the
job training, benefiting both the current inspection effort and the collective level of expertise of the
entire company. It is incumbent on the team leader to take advantage of highly trained and
experienced personnel in this manner to ensure optimal performance of the inspection effort.
Contracted Professionals
There are many advantages to contracting experts in the
field of inspection technology. Professional boiler
inspection team members work together during manyoutages each year. A well traveled professional brings a
wealth of expertise and experience to the outage. He is a
valuable source for vital technical information.
Professional consultants should be utilized extensively to
conduct on the job training during the inspection period.
Effective paring will facilitate this goal.
The selected inspection contractor should bring
experience and knowledge of your specific equipment and
the industry in general. They should be knowledgeable in
all aspects of team activity as it pertains to your inspection
program. They should be skilled, efficient, competent and
able to easily adapt to your inspection program. If you use specific software as part of your inspection
program, your contracted inspectors should be knowledgeable in those areas as well. It is important to
research prospective inspection contractors thoroughly to ensure your technical requirements are met.
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Outage management:
Cost Control
The process of cost containment is not just a reduction of total costs. Cost control can only be effective
if we focus the monies available in just the right locations. The shot gun approach or the process of
spending money for the sake of using up the budget will not provide relief from tube leaks. More money
does not necessarily translate into lower availability.
How to maintain our repair budget
The most effective way to maintain your repair
budget is to provide a comprehensive plan
supported by inspections, lab results or other
scientific results. This plan must have a financialcomponent indicating the return on investment in
the repairs. Data driven decision making is the only
consistently effective method to support budgets. In
many cases the data is best supported by good
photography of the problem areas, as well as a
statistical analysis of failures or near failures that
will likely be avoided. Varying lost generation
scenarios at different times of the year usually works well at underpinning your budget requests.
Simple, concise, data supported, and to the point is always more effective than the Chicken Little The
sky is falling technique.
The quality and quantity of your inspections and subsequent data gathered typically has a positive
physiological impact on financial decision makers. A compelling case well presented is likely to develop
more money over time than a more abstract approach.
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Inspections beyond availability
We have been reminded recently that boiler inspections are not completed just to improve availability.
Inspections have from the beginning of boiler operation, been a tool to prevent loss of life and injury to
the public. We have been historically successful in application of the ASME rules for construction and
repair to a point where the personal injury objective has been over shadowed by the desire to improveunit availability and performance. Our national fleet average age is now approaching a critical point
where years of operation have caught up with us. We can expect problems to arise that have not
traditionally been a problem. Things such as corrosion fatigue, under deposit corrosion, and cold side
corrosion to name a few, will become more prominent going forward. In many cases these problems are
especially dangerous since they will likely fail to the cold side or outside the boiler proper. These are
significantly more dangerous to personnel
than historic tube failures.
The methodology for outage repair planning
has been to consider the problems that have
occurred in the past, and proactively repair
and replace based on that knowledge. This
method has served us well in that tube leak
failure rates have been maintained below 4%
nationally. This method is likely to fall short
in the future since the expected problems
will not have history to support our activities.
In some cases, we will have first time failures.
These failures can be devastating when a loss
of life or injury occurs in the process.
Since we have the scientific and accumulated knowledge of these potential leaks, they are preventable.
This is where the problem occurs. It is indefensible to have a personal injury when the means and
knowhow were available to prevent the loss. We will be held accountable if we do not act.
Unfortunately this approaching tube leak problem occurs when budgets are under financial pressure
due to economic restraints. We have to factor in the ethical and financial impact of a loss of life and/or
injury due to our failure to act to prevent the failure.
When budgets are tight, the boiler inspection effort has traditionally been reduced or eliminated for the
outage execution. This thinking has to be reversed. As the boiler equipment ages, the likelihood of
failure increases therefore the inspection and repair budget need to expand, not contract.
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Boiler/Steam Generator:
The primary cause of unavailability of our fossil -fired plants is the reliability of the boiler/steam
generator. Severe duty on both the fire side and the water/steam side of the various heat transfer
surfaces in the boiler/steam generator cause frequent unplanned outages and lengthening of planned
outage failures to these critical components of the power plant. Replacement of these components willsignificantly reduce outages and increase the facility's availability and total generation output capability
and emissions.
In the past the three primary areas of the boiler system were compartmentalized. These areas were;
Pulverizer / Burners
Boiler pressure parts
Emissions control equipment
It is known that by combining all
three into one model. Treating thesystem as a whole not individually
we can achieve far more
constructive results than by three
separate non overlapping
approaches. This holistic approach
creates many opportunities that
never were identified before
application of this methodology.
This synergistic approach is not new
as Aristotle concluded The whole ismore than the sum of its parts
thousands of years ago. Our
industry is just beginning to embrace
this concept as experts in these
three fields are interacting to
improve the overall outcome of
availability, sustainability,
performance and emissions.
Plant efficiency, availability, emissions, and safety are determined by process inputs and outputs fromthe coal yard to the stack. The economic and operating benefits of managing and improving the
complete process are substantial.
The alliance seen in the graphic was formed to be a foundation of area specific experts able to facilitate
the coordination of functioning initiatives within power plant groups. This joint effort results in
improved boiler reliability, plant efficiency, and overall environmental impact.
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Combustion, boiler pressure parts, and emissions:
When we take a holistic approach to the plant maintenance and operational challenges we must
consider some of the factors listed and how they interact with the entire process.
Coal
Bituminous coals from Eastern mines, sub-bituminous and lignite coals from Western mines, and
lignites from Texas mines are substantially different from each other in the combustion process. Coal
blending is now used for operational and financial benefits. This results in a wide range of boiler and
precipitator operating conditions.
Precipitating fly ash from difficult coals can be improved with conditioning systems. However, the
furnace and its associated equipment can still cause problems in the precipitator, particularly coal mills,
burners, and air pre-heaters.
Coal Mills
The setting of the coal mills and classifiers defines the coal particle size which in turn impacts the fly ash
particle size. Larger coal particles are more difficult to combust, but larger fly ash particles are easier to
collect in the precipitator.
Furnace
Base-load operation of the boiler is usually better for precipitator operation than swing-load operation
due to more stable operating conditions. Boiler operation at low loads may be as problematic for the
precipitator as operating the boiler at its maximum load level, due to fallout of fly ash in the ductwork,
low gas temperatures, and deterioration of the quality of the gas velocity distribution.
If low load operation cannot be avoided, the installation of additional gas flow control devices in the
inlet and outlet of the precipitator may prove beneficial.
Coal Burner
The operation of coal burners, together with the setting of the coal mills and their classifiers, affects the
percentage of unburned carbon (LOI or UBC) in the fly ash. The use of Lo-NOx burners increases this
percentage, and causes re-entrainment and increased sparking in the precipitator. Further, the UBC
tends to absorb SO3, which in turn increases the fly ash resistivity. Over-fire air optimization or coal-
reburn systems may reduce UBC in the fly ash.
Air Pre-heater
Regenerative air pre-heaters cause temperature and SO3 stratification in the downstream gas flow. This
problem is more severe in closely coupled systems, where the precipitator is located close to the air pre-
heater. Depending upon site-specific conditions, flow mixing devices may be installed in the ductwork to
the precipitator, or flue gas conditioning systems may be used to equalize the gas flow characteristics.
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Fly Ash and Flue Gas Conditioning
Flue gas and fly ash characteristics at the inlet define precipitator operation. The combination of flue gas
analysis, flue gas temperature, and fly ash chemistry provides the base for fly ash resistivity. Typically, fly
ash resistivity involves both surface and volume resistivity. As gas temperature increases, surface
conductivity decreases and volume resistivity increases.
In lower gas temperature ranges, surface conductivity predominates. The current passing through the
precipitated fly ash layer is conducted in a film of weak sulfuric acid on the surface of the particles.
Formation of the acid film (from SO3 and H2O) is influenced by the surface chemistry of the fly ash
particles.
In higher gas temperature ranges, volume conductivity predominates. Current conduction through the
bodies (volume) of the precipitated fly ash particles is governed by the total chemistry of the particles.
Fly ash resistivity can be modified (generally with the intent to reduce it) by injecting one or more of the
following upstream of the precipitator:
Sulfur trioxide (SO3) Ammonia (NH3) Water
Sulfur Trioxide and Ammonia Conditioning Systems
In most cases, a sulfur trioxide conditioning system is sufficient to reduce fly ash resistivity to an
acceptable level. The source of sulfur trioxide can be liquid sulfur dioxide, molten elemental sulfur, or
granulated sulfur. It is also possible to convert native flue gas SO2 to SO3.
In some instances, ammonia alone has been proven a suitable conditioning agent. It forms an ammonia-
based particulate to increase the space charge. The source of ammonia may be liquid anhydrous or
aqueous ammonia, or solid urea.
Finally, sulfur trioxide and ammonia may be used in combination. This solution has been successful
because it can lower fly ash resistivity and also form ammonia bisulfate. The latter increases the
adhesion of particles, and thus reduces re-entrainment losses.
Water Injection
The injection of water upstream of the precipitator lowers the gas temperature and adds moisture to
the flue gas. Both are beneficial in cold-side precipitator applications. However, care must be taken that
all of the water is evaporated and that the walls in the ductwork or gas distribution devices do not get
wet.
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Streamline the inspection and repair process:
This work shop has discussed the importance of certain procedures and practices during these
challenging economic times; however, organization and execution of these procedures and practices are
required to make a difference. It is understood that you need trained and qualified personnel toperform your work. Once you develop your
plan of maintaining your assets with the
resources you have available, the next step
is to organize the practices and then you
need to execute. If it is part of your outage
plan to have inspection crews only record
priority 1 items (any item identified that
will bring the unit off-line prior to the next
scheduled shut down), then these P1 items
will require supervision to ensure the
repairs are made. Making a successful
repair and executing above and beyond the
initial process of finding the damage is
imperative. The follow through and
execution of this process is vital. If the
preparations and plans for an inspection
team include particular items of equipment,
the process of getting all of this equipment
on site in time for inspections would be to
execute the process. Every part of the
inspection and repair process started with a
plan, and should end with execution.
The organize and execute method is important when efforts are being made to streamline the
process. If we are limited on resources, we need to optimize the process. Follow these steps:
1) Plan2) Organize3) Execute4) Follow up
There is synergy between the execute and follow up stages. For whatever part of the plan that did not
get executed properly, there will be a follow up plan to satisfy the agenda. If a particular damage
mechanism was identified, however the repair was not performed and executed , the follow up will
begin the next step. The follow up may include future plans, or maybe an adjustment that still supports
the original organized plan.
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