CPS Spruce Unit 1

Optimization History

Joe Sepulveda - Manager, Maintenance

CPS Energy Spruce Plant

May 25, 2011

CPS Energy

Nation’s largest

municipally-owned

provider of electric

service and natural

gas

Located in 7th largest

city in USA

Provides services to

~707,000 electric and

322,000 natural gas

customers

CPS Generation

35% of CPS Energy’s power comes from coal fired generation

CPS has four coal fired units: JK Spruce 1 and 2

JT Deely 1 and 2

These 4 units and the Sommers gas plant located at the Calaveras power station

Coal-fired Units

Deely 1 and 2 are Alstom-CE tangentially

fired sub-critical units rated at 440 MWs

and commissioned in ’77 and ’78

Spruce 1 is an Alstom-CE tangentially fired

sub-critical boiler commissioned in 1992

that normally runs at 585 MW

Spruce 2 is an Alstom unit with SCR and

FGD that began commercial operation in

May 2010; normally runs at 818 MW

Units use PRB coal

Capacity factors of over 90%

CPS Energy NOx Reduction

History

1998 voluntarily committed to reduce NOx by

15 - 20%

Success achieved through:

• Combustion control tuning

• Staging of primary and secondary combustion air

• Installation of low NOx nozzle tips

• Attempted balancing coal flow through coal pipes with no

success

Derived benefits:

• Smaller SCRs

• Lower associated capital and O&M costs

CPS Energy NOx Reduction

History

TCEQ and State Senate enacted NOx rules in 2000

CPS Energy was required to reduce NOx emissions

by 50% by 2005 compared to emissions from ’96-’98

CombustionOpt installed at Spruce 1 in 2001/2002

Followed by CombustionOpt on both Deely units in

2004

Optimization objectives:

Primary objective: further reduce NOx emissions

Secondary objective: improve heat rate

Spruce Unit 1

CE T-fired unit

585 MW

LNB’s, SOFA

Six mills

PRB coal

98 wallblowers (IRs), 44 retract blowers (IKs), and 2

air preheater blowers (APHs), steam media

Emerson Ovation Distributed Control System (DCS)

OSI PI data historian

Diamond SBCS uses Allen Bradley PLC with HMI

configured in RSView

Initial CombustionOpt

Implementation

Project kick-off: July 2001

DCS integration complete by early September

Neural optimizer was on-line and operating in

closed-loop by late October

As CPS engineers became familiar with the

technology, they worked with NeuCo engineers

to fine-tune optimizer to maximize benefits

This included modifying system to handle plant

constraints and prioritization of NOx and CO

constraints

Initial NOx Results

Improvements Over Time

ProcessLink Upgrade

More robust; access to more technologies

Improved visibility, benchmarking, interface

Added Expert Rules

To address feeder issues at low load

Model Predictive Controller

Suited to dynamic operating conditions

Used for manipulating O2 bias

Tuning as needed

Changes to objectives, constraints, equipment

Addition of SootOpt

SootOpt project started May 2010

Justification

Concern about erosion in economizer area

• ‘09 blower inspection indicated high wear

Efficiency increasingly important to plant

• 0.375% HR improvement justifies investment

Site visits important

Addition of SootOpt

Goals:

Reduce sootblowing in high wear areas

Improve heat rate

Improve SH and RH temp control (reduce excursions)

during load ramps

Ensure side-to-side steam temp delta does not

significantly increase

• Reduce delta if possible

While:

Maintaining NOx at 0.125 lb/MMbtu or further

reducing it

Adhering to CO limits

Spruce 1 Heat Rate

Considerations

Heat Rate indicators to consider:

Internally-calculated heat rate

NeuCo Heat Loss Indicator (HLI) calculation

• Summation of 5 losses affected by BoilerOpt into a single

index

Other indicators of heat rate changes

• Attemperation sprays, steam temperatures, gas

temperatures, sootblowing activity, etc.

Relative heat rate trends over longer time periods

Note: Heat rate goes into the 10,000’s when coming

down in load at night

Operations Before SootOpt

Diamond Soot Blowing Control System (SBCS)

SentrySeries - 2005

SBCS running on Allen Bradley programmable logic

controller (PLC)

Sootblowing performed based on Operator judgment:

Some Operators picked individual blowers based on

experience

Others picked when to blow but used existing sequence

definitions

Ops used sootblowing to lower exit gas temps which tend to

run high at high load

Operations Before SootOpt

Control loops generally in automatic mode: Aux air

SOFA

Fuel/Air

Mills

Mill temperature control

Fans

RH and SH attemperation sprays

Control loops generally in manual mode: Underfire air – yaws and tilts set manually and locked

Burner tilts

SootOpt Installation Steps

Budget Approval April, 2010

Kickoff May 3, 2010

PI/ PLC communications established June 30, 2010

Initial blower and zone configuration June 30, 2010

PLC modifications June 30, 2010

Initial closed-loop configuration Aug. 17, 2010

SootOpt in sustained closed-loop operation Oct. 6, 2010

SootOpt in routine use Nov. 5, 2010

Analysis projects (GUI) completed Nov. 16, 2010

Model tuning Oct-Dec, 2010

Final training Feb. 21, 2011

Spruce Resources During

Implementation

Multi-discipline group involved in kick-off & goal

setting

I/C team involved in system integration

For final tuning stage, Chief Ops Manager &

Maintenance Manager more involved

NeuCo & operators interact directly with

questions or if something unexpected seen

Operators very knowledgeable and helpful

SootOpt Implementation

Operations Input (examples)

In summer, APH gas inlet temp may need to be reduced

to prevent absorber tower temps from exceeding trip limits

SootOpt must consider potential temp overshoot/lag

during during ramp up/ramp down

Only operate one retract blower at a time in front east,

front west, back east, and back west sections

Larger blowers that require higher steam flow should be

run only if main steam pressure is greater than 1900 psi

Ops suggested limiting wallblower actuations at lower

loads even if SH steam temperature is running a bit

higher, because the temperatures would suffer when the

Unit started picking up load

System Hardware

Configuration

SB

HMI

NeuCo

ProcessLink SootOpt

CombustionOpt

DCS PI Historian

SB Control

System

(PLC)

PI Driver

DCS Consoles

Process I/O

SB I/O

NeuCo Remote Access

Plant

Firewall

VPN

Firewall

Operator Interface

Plant Interaction with SootOpt

No dedicated resource

Process:

Maint. Mgr point person for significant adjustments

Communicates with Chief Ops Mgr who handles

implementation with NeuCo and operators

On smaller issues Operators provide feedback

direct to NeuCo and respond to NeuCo questions

Adopted new approach to IK maintenance

Every Wednesday vs. Ad Hoc

Things to Consider When

Implementing SootOpt

Plan for SootOpt, SBCS and data historian

integration/communication

Get operations feedback & address concerns

quickly

Interact with all shifts

CPS & BoilerOpt Current

Status

Ongoing efforts to improve performance:

Adjustments based on operations feedback

Addressing load swings & summer temperatures

Mill-specific models

Incorporating new boiler tube inspection data

Budgeted to install SootOpt on both Deely

units this year

Questions?