# ELECTROSTATIC PRECIPITATOR

UNI T 5 & 6

EVALUATION REPORT

ADDITIONAL COLLECTI NG AREA

NRG OSWEGO HARBOR POWER LLC
261 Washington Boulevard Oswego, New York 13126

Date March 25, 2012

Prepared by Kenneth Aken Keith Bradburn Thomas Keeler


## TRK ENGINEERING SERVICES, INC.
95 Clarks Farm Road Carlis le, Massachuset ts 01741, USA 978-287-0550 trkeng@apcnetwork.com

TRK Report # NROS120326NRG Oswego I. INTRODUCTION

NRG has requested T R K Engineering to pr ovide an overview cost for adding an additional field to Oswego Harbor Power Un it 5 and 6 electrostatic precipitators.

Unit 5 and 6 are identical units with a rat ed capacity of 850 MW. Unit 5 was completed in 1975 and Unit 6 in 1980. The boilers were furnished with Joy Western weighted wire precipitators to remove filterable particulate. Each unit has four precipitators arranged to operate in parallel wit h two side by side at a lower level and two arranged at an upper elevation above the lower units giving a f our square arrangement. Since both systems are similar only one Unit is being evaluated in this report.

The boiler, ESPs, ductwork and fans are all enclo se d in a superstructure building. This makes the demolition and inst allation of any new equipment very difficult. TRK Engineering looked at several different meth ods to add additional c o llecting area/fields to the ESPs. Because of the ductwork and boi ler location addin g the new field to the inlet of the ESP app ea rs to be impossib l e, therefore the outlet of the ESP is the only viable locat i on.

To add an additio nal 6 foot field to the ESPs will requ ire all of the outlet nozzle and ductwork to be removed and replaced with a new design. A new casing, internals, hopper, ash removal system, ra pper system, pow er supplies and f oundations will need to be installed. The superstructure for t he system will need to be dismantled, modified and reinstall to accommodate the in stallation and additional space needed.

TRK Report # NROS120326 1NRG Oswego Side view of existing ESP

Side vie w o f ESP with the new outlet field

TRK Report # NROS120326 2NRG Oswego II. ESP DESIGN

From the material supplied by NRG the following data was found or calculated. The following is a list of the original design data supplied comparing it with the proposed additional field in place.

Description Units Existing Proposed

L o a d M W 8 5 0 8 5 0
Number of precipitators # 4 4

Number of series fields # 5 6
Length of series fields ft 6 / 9 / 9 / 9 / 6 6 / 9 / 9 / 9 / 6 / 6
Total treatment length f t 3 9 4 5
# of cells per precipitator # 4 4
# of gas passages per cell # 2 3 2 3
# of gas passages per ESP # 9 2 9 2
Collector plate height f t 3 0 3 0
Collector plate spacing i n 9 9
Aspect ratio # 1

. 3 0 1

. 5 0
Collector plate area per ESP ft 2 2 1 5

, 2 8 0 2 4 8

, 4 0 0

Total collec t or plate area ft 2 8 6 1

, 6 2 0 9 3 3

, 6 0 0

Calculated Gas Volume acfm 3,200,000 3,200,000
Flue gas velocity ft/s 6.44 6.44

Treatment time sec 6.05 6.98
SCA (Spec ific Collecting Area) @ 9” 269 310

III. PERFORMANCE IMPROVEMENT

The addition of a 6 ft fi eld would y i eld a 15.38% increase in plate area and treatment time. There would als o be an increase in the as pect ratio form 1.3 to 1.5. All of these factors would increase t he efficiency of the ESP.

Assuming that the removal efficiency is 99. 33% with an emission of 0.06 lb/mmBtu then with the addition of an additional field of this si ze the emissions is predicted to reduce by 31% to 0.041 lb/mmBtu.

TRK Report # NROS120326 3NRG Oswego IV. SCOPE OF W O RK

Scope of work needed to install an additional 6 ft field for each of t he four preci p itators would include the following.

Site Inspection

• Examine precipitator, assess physical ar ea, structural steel to be removed, assess stru ctural steel that w ould receive additional loads.

• Identify locations for addi tional required foundations.

• Identify building rewor k

.

• Examine power load c enter for capacity.

• Examine fly ash remo val system for capacity and additional lines.

• Evaluate c onstructability fo r the addition al field.

• Check for presence of lead paint and asbestos.

• Examine gas distribution for flow balanc e between precipitators and internal flow distribution

Engineer and Supply

• Casing side walls, int e rnal bracing, t op plate, hoppers, replacement transitions and ductwork.

• Supporting structures.

• Precipitator internals, collector plat es and suspension, discharge electrodes and suspension systems, Collector plat e and discharge electrode rapping systems

• Additional transformer- rectifie rs and associated equipment and controls

• Additional controls for rapping systems.

• Additional hopper acc e ssories, heaters, level ind i cators etc

• Modify and extend ins u la tor heated purge air systems.

• Modify external access

• Additional hopper flyash remova l valves and evacuation lines.

• Design Foundations

Site Work

• Install addit i onal foundations

• Evacuate and clean down existing precipitators.

TRK Report # NROS120326 4NRG Oswego • Remove /demolish existing boiler build ing structural components and sheeting to give acces s and allow for additional field.

• Install provisional steel as required.

• Remove thermal insulation and cladding fo r precipitator trans ition nozzles and ductwork as required.

• Remove existing transition nozzles from precipitators and ductwork as required.

• Install supporting steel structures.

• Install the additional casing struct ures and hoppers for t he precipitator’s additional field.

• Install transition nozzles and ductwork.

• Install thermal insulation and cladding.

• Install building structural and siding

• Install all internal components, suspensions and rapping systems.

• Install addit i onal transformer rectifiers.

• Install addit i onal transformer re ctifier and rapper control panels.

• Install low voltage wiring, cable and conduit.

• Check out and commission the precipitat or’s additional field for service.

V. BUDET ARY COS T ESTIMATES

To add an additio nal 6 foot field to the ESPs will requ ire all of the outlet nozzle and ductwork to be removed and replaced with a new design. A new casing section, internals, hoppers, ash removal system, ra pper system, power supplies and foundations will need to be installe d. The superstructur e for the system will nee d to be dismantled, modified and reinstall to accommodate the installation and additio nal space needed. This will require approximately 16 to 24 weeks of outage time to accomplish.

Based on s i milar projects of this complexi ty and size TRK Engineer ing estimates the budgetary cost would be $15.2 million dollar s per unit.

Desig n , engineer and supply wo u l d be $6.1 milli on dollars and demolition, in stallation and site wo rk would be $9.1 millio n dollars

The above does not consider the cost of any loss of power generation or other outage related costs.

TRK Report # NROS120326 5