ELECTROSTATIC PRECIPITATOR 

UNIT 5 & 6 

EVALUATION REPORT 

ADDITIONAL COLLECTING 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 

Carlisle, Massachusetts 01741, USA 

978-287-0550 

trkeng@apcnetwork.com 

TRK Report # NROS120326 
 NRG Oswego 

I. INTRODUCTION 

NRG has requested TRK Engineering to provide an overview cost for adding an 

additional field to Oswego Harbor Power Unit 5 and 6 electrostatic precipitators. 

Unit 5 and 6 are identical units with a rated 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 with two side by side at a lower level and two arranged at an upper 

elevation above the lower units giving a four square arrangement. Since both systems 

are similar only one Unit is being evaluated in this report. 

The boiler, ESPs, ductwork and fans are all enclosed in a superstructure building. This 

makes the demolition and installation of any new equipment very difficult. TRK 

Engineering looked at several different methods to add additional collecting area/fields 

to the ESPs. Because of the ductwork and boiler location adding the new field to the 

inlet of the ESP appears to be impossible, therefore the outlet of the ESP is the only 

viable location. 

To add an additional 6 foot field to the ESPs will require all of the outlet nozzle and 

ductwork to be removed and replaced with a new design. A new casing, internals, 

hopper, ash removal system, rapper system, power supplies and foundations will need 

to be installed. The superstructure for the system will need to be dismantled, modified 

and reinstall to accommodate the installation and additional space needed. 

TRK Report # NROS120326 1 
 NRG Oswego 

Side view of existing ESP 

Side view of ESP with the new outlet field 

TRK Report # NROS120326 2 
 NRG 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 

Load MW 850 850

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 ft 39 45

# of cells per precipitator # 4 4

# of gas passages per cell # 23 23

# of gas passages per ESP # 92 92

Collector plate height ft 30 30

Collector plate spacing in 9 9

Aspect ratio # 1.30 1.50

Collector plate area per ESP ft2 215,280 248,400

Total collector plate area ft2 861,620 933,600

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 (Specific Collecting Area) @ 9” 269 310 

III. PERFORMANCE IMPROVEMENT 

The addition of a 6 ft field would yield a 15.38% increase in plate area and treatment 

time. There would also be an increase in the aspect ratio form 1.3 to 1.5. All of these 

factors would increase the 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 size the emissions is predicted to reduce by 

31% to 0.041 lb/mmBtu. 

TRK Report # NROS120326 3 
 NRG Oswego 

IV. SCOPE OF WORK

Scope of work needed to install an additional 6 ft field for each of the four precipitators 

would include the following. 

Site Inspection

• Examine precipitator, assess physical area, structural steel to be removed, 

assess structural steel that would receive additional loads. 

• Identify locations for additional required foundations. 

• Identify building rework. 

• Examine power load center for capacity. 

• Examine fly ash removal system for capacity and additional lines. 

• Evaluate constructability for the additional field. 

• Check for presence of lead paint and asbestos. 

• Examine gas distribution for flow balance between precipitators and internal flow 

distribution 

Engineer and Supply

• Casing side walls, internal bracing, top plate, hoppers, replacement transitions 

and ductwork. 

• Supporting structures. 

• Precipitator internals, collector plates and suspension, discharge electrodes and 

suspension systems, Collector plate and discharge electrode rapping systems 

• Additional transformer- rectifiers and associated equipment and controls 

• Additional controls for rapping systems. 

• Additional hopper accessories, heaters, level indicators etc 

• Modify and extend insulator heated purge air systems. 

• Modify external access 

• Additional hopper flyash removal valves and evacuation lines. 

• Design Foundations 

Site Work

• Install additional foundations 

• Evacuate and clean down existing precipitators. 

TRK Report # NROS120326 4 
 NRG Oswego 

• Remove /demolish existing boiler building structural components and sheeting to 

give access and allow for additional field. 

• Install provisional steel as required. 

• Remove thermal insulation and cladding for precipitator transition nozzles and 

ductwork as required. 

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

• Install supporting steel structures. 

• Install the additional casing structures and hoppers for the 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 additional transformer rectifiers. 

• Install additional transformer rectifier and rapper control panels. 

• Install low voltage wiring, cable and conduit. 

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

V. BUDETARY COST ESTIMATES 

To add an additional 6 foot field to the ESPs will require 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, rapper system, power supplies and foundations 

will need to be installed. The superstructure for the system will need to be dismantled, 

modified and reinstall to accommodate the installation and additional space needed. 

This will require approximately 16 to 24 weeks of outage time to accomplish. 

Based on similar projects of this complexity and size TRK Engineering estimates the 

budgetary cost would be $15.2 million dollars per unit. 

Design, engineer and supply would be $6.1 million dollars and demolition, installation 

and site work would be $9.1 million dollars 

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

related costs. 

TRK Report # NROS120326 5