Managing Coal Assets under Flexible Operations

© 2015 Electric Power Research Institute, Inc. All rights reserved.

Managing Coal Assets

under Flexible

Operations

Revis W. JamesSenior Technical ExecutiveGeneration Sector Research and Development

Workshop on Best Practices in Production of Electricity from CoalUnited Nations Economic Commission for Europe29 October 2015

2© 2015 Electric Power Research Institute, Inc. All rights reserved.

Flexible Operations:

Plant Design Versus Plant Capability

Normal Operating

Range

Normal Operating

Range

Alarm Limit Transient Region Automatic Action Design Limit

(Trip Point)

Understanding, Utilizing and Optimizing Design and Operating Margin


The Impact of Changing Missions

1. Increased Routine Damage with Less Operation

2. New ‘Unpredictable’ Damage Models


The Power System – Looking to the Future

Power

Flow

A More Dynamic End-to-End Power System

Generation Becomes

More Flexible

Consumers Become

Energy Producers

T & D Becomes More

Controllable and Resilient

Loads

Become More

Interactive and Dynamic


Operational Flexibility Driven by Evolving

Electricity System

Increasing renewable

energy, distributed

generation, automated

load management

Increase Fossil

Efficiency and

Flexibility

Improved

Environmental

Controls Technology

Flexible, dispatchable assets support increasing generation, demand variability

Improved environmental controls technologies enable continued availability of dispatchable fossil units

Flexible environmental controls technologies necessary to increased fossil unit flexibility


Flexible Operations Drives Challenges at the

Fleet and Unit Level

Fleet planning and management– How can future fleet maintain/improve operational flexibility?

Ensuring availability of adequate dispatchable capacity

Operational flexibility needs driven by both variability and ancillary services

– How to incorporate value of operational flexibility into definition of

“cost-effective” at fleet level?

– How to define optimum asset management strategy?

Unit operations– Developing operator understanding of effects on emissions control

systems during flexible operations.

– Developing operator understanding of balancing availability and

reliability with needs for flexibility and environmental compliance.

– Developing/adopting appropriate staff training?


Drivers

Operational flexibility and shifts in capacity factors– Increasing renewable generation share

Aging plants nearing retirement

More stringent emissions requirements

Limited operations and maintenance (O&M) budgets, technical staff, and capital resources

Unintended consequences, system interactions and reduced design margins

Results in “changing mission profiles” for coal and gas plant operations.

Meet environmental constraints while operating more flexibly

but balance cost, reliability/availability, performance


Modes

– Extended Lay-up

– Turndown to 25-30% Load (without selective catalytic

reduction [SCR])

– Load-Following (with SCR)

– Cycling (daily start/stop)

Constraints/challenges

– Varying fuel quality

– Environmental compliance (i.e. mercury, particulates,

sulfur, SOx/NOx)

Changing Mission Profiles Pilot Project

Factors Driving Different Mission Profiles


U.S. Utility Perspectives:

Key Unit Design/Mission Profile Combinations

Other Key Issues

• Ramp rate improvements for coal,

gas/oil boilers

• Consider mission of managing units to a

specific limited life (coal)


Geographical Distribution of Pilot Studies

Ontario, Canada

Possible


Unit Level Operations

Key Issues/Insights

Sustained operations at minimum load

Combination of low load and need for fast ramp rates is

large challenge

Flue gas desulfurization (FGD) and other environmental

control equipment issues have high priority

Greater need for guidance where layup duration is uncertain

Budget uncertainty limits available options

Anticipated impacts of key issues on plant staff is high

Value of cross-functional, multi-discipline team to prioritize

issues, identify potential solution strategies


Specific Technical Challenges with

Key Missions

Increased minimum load operation for coal; avoid cycling– Implications for boiler feed pump (BFP) operation– Combustion and NOx compliance; controls tuning– Ramp rate management

Increased shutdowns– Layup and equipment preservation– Freeze protection– Reduced spending and relaxing equivalent forced outage

rates (EFOR) targets (e.g., seasonal)

Increased capacity factors for combined cycle fleet => base load operation– Increased interval between outages – technical basis

needed


Future Needs/Solutions

Staffing

– Smaller operating envelope challenges operations staff

– Reduced maintenance and engineering – relying on original equipment suppliers and third-parties

– Sharing of staff between plants and between O&M disciplines

– Using simulators to help maintain competence

as staff move between plants

to train for different mission profiles

– Investments in monitoring & diagnostic (M&D) centers

Specific technical concerns

– Checklist for off-design operation

– Increased wear on breakers (safety topic), boiler feed pump maintenance

– Increased generator rewinds and transformer failures

– Increased corrosion issues on layup on boilers/turbine-generator

– High pressure valve packing; on-line turbine stress analyzers (fast start)

– “Remaining Life Costs” of existing units – determining optimum added investment


Closing Thoughts

The importance of dispatchable assets increasing, driven by more renewables, distributed resources, and customer management of energy consumption and loads.

The need for flexible operations in dispatchable assets, including coal, will grow.

Fundamental materials, chemistry and component reliability research and development build the foundation for enabling flexible operations of coal units.

Technology adoption and Operations & Maintenance strategies enable flexible operations

Both new and existing assets will need increased operational flexibility.


Together…Shaping the Future of Electricity


Overview of Research Activities on Changing Mission Profiles

Changing Mission Profiles Pilot study– Examining actual experience at coal and gas units experiencing significant

flexible operations.

Mission Profiles Working Group– Facilitate exchange of experience between power companies

– Develop generic research and tools to assist asset management decisions for

fleets experiencing diverse mission profiles.

Next steps– Modify/augment current research programs to address new challenges

created by increasing flexible operations and diversity in

different mission profiles

– Key areas: maintenance, component reliability, operation &

management approaches


EPRI Research at Unit and Fleet Level

MP Pilot Project

R&D Portfolio

MPWG

Member Initiatives

Addressing unit level issues created by new

mission profiles

Planning

operational

flexibility into

future fleet

Unit Level Research:

Changing Mission Profiles

Fleet Level Research:

Enabling Central Station Flexible Operations


Criteria Definition

Impact on corporate

metrics?

•How does this issue impact corporate performance indicies and related metrics

(i.e., safety, reliability, cost)? Overall, how important is this issue to the business?

•High impact = High rank

Acceptable options? •Are there good solution alternatives?

•Are there acceptable options with a clear understanding of compromises such

that decisions can be made?

•No = High rank

Available technical

resources?

•Are solutions available through EPRI or other organizations?

•Are applicable peer experiences available?

•No = High rank

Degree of

uncertainty?

•Do we understand the technical basis for the issue and for the solution path

forward? Are all elements of the resolution well understood?

•No = High rank

Impact on plant staff

and O&M?

•How will the solution to the issue be sustained and impact the plant staff

(operators, maintenance, crafts, technicians, etc.)? Will the solution be easily

accommodated within existing plant resources (i.e., processes, systems, staffing,

etc.)?

•High negative impact on plant staff resources = High rank

Changing Mission Profiles Pilot Project:

Issue Prioritization -- Criteria


Pilot Studies of Specific Units

Mission Profiles

Unit TypeReduced/ minimum

load

Load following

2-ShiftingLayup

(short and extended)

Other

Subcritical PCFirstEnergy/

SammisDuke/ Cliffside 5

Supercritical PCLuminant/ Monticello

FirstEnergy/Sammis

Gas boilerEntergy/ Ninemile,

Little Gypsy

Entergy/ Ninemile,

Little Gypsy

CT/CC SRP/Santan

Oil-fired Boiler HECO?

HydroOPG/Thunder

Bay


Interpretation of Unit Design/Mission Profile Priorities

Pulverized Coal

Highest interest in low turndown – sub and supercritical units

– High interest in ramp rate improvements for both

Higher interest for both short-term shutdown and extended

shutdown for subcritical than for supercritical – both important

– Limited life of subcritical units

No interest yet for two-shifting – is this “around the corner?”

Hydropower

Priorities are (in order) load follow, low turndown, and two-shifting

– Concerns for increased equipment wear (i.e., sluice gates)


Interpretation of Unit Design/Mission Profile Priorities

Oil boilers

Priorities are low turndown, then ramp rate improvements, and shutdown

Gas boilers

Priorities are shutdown periods (short/extended), then low turndown

Combined cycle

Priorities are low turndown and load follow (and ramp rate improvement), then two-shift and short-term shutdown


Generation Becomes

More Flexible

Consumers Become

Energy Producers

T & D Becomes More

Controllable and Resilient

Loads

Become More

Interactive and Dynamic

Impact to the Existing Fossil Fleet

Need to Achieve New Mission Profiles in Bulk Central Generation

Frequency of

Startups and Shutdowns

Greater Turndown /

Minimum Load Goals

Increasing Ramp Rates

Unit Layups


Alarms per Position - Configured

An Evolving Industry Creating New Challenges

Standardized, Digitized and Centralized is the Future of Power Generation


The Impact of Changing Missions

Life cycle equivalent forced outage factor for

conventional plants operating in the base load

mode and cycling regime

Life cycle equivalent forced outage factor for CCGT

plants operating in the base load

mode and cycling regime

Coal CCGT

The Least Impactful Mode of Operation is Base Load Operation


Fundamental Material Research Critical

Changing Missions Leading to Unanticipated Failures


Repair Techniques that Enable Safe Operation

Well-Engineered Welds Prevent Catastrophic Failures


Damage Prevention through Innovative Techniques

▪ Increasing flexible operations has increased the risk

from offline damage mechanisms such as turbine

pitting, corrosion fatigue and boiler tube pitting

▪ Filming amine treatments are emerging technology

that have the potential to provide enhanced offline

corrosion control through the formation of corrosion

inhibiting films

Corrosion Fatigue LP Turbine Pitting

Reheater Pitting

Filming amines prevent

corrosion through

formation of corrosion

inhibiting films on metal

surfaces


Fundamental Engineering Principles and Research

The Next Phase of Evolution

Merging Technology and Flexibility

▪ More stringent emissions requirements

(including CO2)

▪ Unintended consequences, system

interactions and reduced design margins (e.g.,

environmental controls systems performance)

▪ Limited O&M budgets, staff, and capital

resources

▪ Transitioning Workforce


Using Technology to Provide FlexibilityC

ON

NE

CT

ED

NE

SS

UNDERSTANDING

ACTIONABLE

INTELLIGENCE

Understanding

Principles

INSIGHT

INFORMATION

Understanding

Relationships

DATA

Data Collection

SIGNALS

Understanding

Patterns

ForesightHindsighthow

why

who

what

where

when

Figure courtesy of Duke Energy


Modeling and Optimization

Optimized duct firing operation resulted in ~$1M in annual fuel savings


Data Enables Alternate Operational Strategies

HRSG Stack Damper

Decay rates of HP

drum Tsat studied

Temperature history

of several

shutdown/startup

sequences revealed

average half-life of:

– 13 hours when stack

damper closed

– 10 hours when stack

damper open

Hot restart capability is extended by ~3 hours with stack damper closed

Documents

Managing Coal Assets under Flexible Operations