TOXECONTM RETROFIT FOR MERCURY

AND MULTI-POLLUTANT CONTROL ON

THREE 90-MW COAL-FIRED BOILERS

Public Design Report

We Energies

ADA Environmental Solutions, Cummins & Barnard, and

the Electric Power Research Institute

DOE Cooperative Agreement No. DE-FC26-04NT41766

December 2009
i

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States 

Government. Neither the United States Government nor any agency thereof, nor any of their 

employees, makes any warranty, express or implied, or assumes any legal liability or 

responsibility for the accuracy, completeness, or usefulness of any information, apparatus, 

product, or process disclosed, or represents that its use would not infringe privately owned 

rights. Reference herein to any specific commercial product, process, or service by trade 

name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its 

endorsement, recommendation, or favoring by the United States Government or any agency 

thereof. The views and opinions of the authors expressed herein do not necessarily state or 

reflect those of the United States Government or any agency thereof.
ii

ABSTRACT

This document provides a summary of the design efforts involved in the project 

“TOXECONTM Retrofit for Mercury and Multi-Pollutant Control on Three 90-MW CoalFired Boilers.” This U.S. Department of Energy (DOE) Clean Coal Power Initiative (CCPI) 

project was based on a cooperative agreement between We Energies and the DOE Office of 

Fossil Energy’s National Energy Technology Laboratory (NETL) to design, install, evaluate, 

and demonstrate the EPRI-patented TOXECONTM air pollution control process. Project 

partners included Cummins & Barnard (C&B), ADA Environmental Solutions (ADA-ES), 

and the Electric Power Research Institute (EPRI). The primary goal of this project was to 

reduce mercury emissions from three 90-MW units that burn Powder River Basin coal at We 

Energies’ Presque Isle Power Plant in Marquette, Michigan. Additional goals were to reduce 

nitrogen oxide, sulfur dioxide, and particulate matter emissions; allow reuse and sale of fly 

ash; advance commercialization of the technology; demonstrate a reliable mercury 

continuous emission monitor (CEM) suitable for use at power plants’ and demonstrate 

recovery of mercury from the sorbent.

In addition to the primary air pollution control system, balance-of-plant design considerations 

were addressed. These included booster fans, a compressed air system, an ash handling 

system, ductwork, electrical, and instrumentation and controls. Design considerations of a 

mercury continuous emissions monitor are included in this report.

The costs of equipment and installation for the TOXECONTM and balance-of-plant systems 

were $34.6 million, including the engineering effort.

This project demonstrated a significant reduction in the rate of emissions from Presque Isle 

Units 7, 8, and 9, and substantial progress toward establishing the design criteria for one of 

the most promising mercury control retrofit technologies currently available. The Levelized 

Cost for 90% mercury removal at this site was calculated at $77,031 per pound of mercury 

removed with a capital cost of $63,189 per pound of mercury removed. Mercury removal at 

the Presque Isle Power Plant averaged approximately 97 pounds per year.
iii

POINTS OF CONTACT

Steve Derenne

Principal Engineer

We Energies

333 West Everett Street

Milwaukee, WI 53201

414-221-4443 

steven.derenne@we-energies.com

Robin Stewart

Manager, Contract R&D 

ADA-ES, Inc. 

8100 SouthPark Way, Unit B

Littleton, CO 80120

303-734-1727

robins@adaes.com

Michael H. McMillian

U.S. Department of Energy

National Energy Technology Laboratory

3610 Collins Ferry Road

Morgantown, WV 26507

304-285-4669

mmcmil@netl.doe.gov

Ramsay Chang

Electric Power Research Institute

3420 Hillview Avenue

Palo Alto, CA 94304-1338

650-855-2535

rchang@epri.com
iv

TABLE OF CONTENTS

LIST OF TABLES................................................................................................................... vi

LIST OF FIGURES ................................................................................................................ vii

LIST OF ABBREVIATIONS................................................................................................ viii

GLOSSARY OF TERMS......................................................................................................... x

EXECUTIVE SUMMARY .................................................................................................... xii

1.0 PROJECT OVERVIEW ............................................................................................. 1-1

1.1 Purpose of the Public Design Report.......................................................................... 1-1

1.2 Brief Description of the Project .................................................................................. 1-1

1.2.1 Project Schedule ..........................................................................................................1-1

1.2.2 Project Organization....................................................................................................1-2

1.2.3 Project Description ......................................................................................................1-3

1.2.4 Project Location...........................................................................................................1-4

1.3 Objectives of the Project............................................................................................. 1-5

1.4 Significance of the Project.......................................................................................... 1-6

1.5 DOE's Role in the Project ........................................................................................... 1-7

2.0 TECHNOLOGY DESCRIPTION .............................................................................. 2-1

2.1 Brief Description of the Technology Being Used....................................................... 2-1

2.1.1 Proprietary Information ...............................................................................................2-2

2.2 Overall Block Flow Diagram...................................................................................... 2-2

3.0 PROCESS DESIGN CRITERIA ................................................................................ 3-1

3.1 Design Recommendations for Presque Isle TOXECON ......................................... 3-1

3.2 Baghouse Design Specifications................................................................................. 3-2

3.3 Coal Analysis.............................................................................................................. 3-3

4.0 DETAILED PROCESS DESIGN............................................................................... 4-1

4.1 General Arrangement.................................................................................................. 4-1

4.2 Equipment List............................................................................................................ 4-2

4.3 Baghouse Design ........................................................................................................ 4-2

4.3.1 Inlet Particulate Loading .............................................................................................4-2

4.3.2 Type of Baghouse........................................................................................................4-3

4.3.3 Air-to-Cloth Ratios......................................................................................................4-3
v

4.3.4 Flue Gas Cooling.........................................................................................................4-4

4.3.5 Bag Material and Length .............................................................................................4-5

4.3.6 Cleaning Method .........................................................................................................4-6

4.3.7 Compartments..............................................................................................................4-7

4.3.8 Tube Sheet Pressure Drop ...........................................................................................4-8

4.3.9 Model Study Objectives and Results...........................................................................4-9

4.4 Powdered Activated Carbon System Design ............................................................ 4-11

4.5 Balance-of-Plant Considerations .............................................................................. 4-14

4.5.1 Booster Fans..............................................................................................................4-14

4.5.2 Compressed Air System ............................................................................................4-16

4.5.3 Ash Handling System................................................................................................4-17

4.5.4 Ductwork ...................................................................................................................4-22

4.5.5 Electrical....................................................................................................................4-25

4.5.6 Instrumentation and Controls ....................................................................................4-27

4.6 Mercury Measurements ............................................................................................ 4-28

5.0 PROCESS CAPITAL COST...................................................................................... 5-1

5.1 Additional Cost of Modifications since Start Up........................................................ 5-3

6.0 ESTIMATED OPERATING COSTS......................................................................... 6-1

7.0 COMMERCIAL APPLICATIONS............................................................................ 7-1

8.0 REFERENCES AND BIBLIOGRAPHY OF OTHER PROJECT REPORTS .......... 8-1

Appendix A. PAC Data Sheet

Appendix B. PAC Injection System Flow Diagram

Appendix C. Drawings

Appendix D. Modifications Since Startup
vi

LIST OF TABLES

Table 1-1. Flue Gas Composition Downstream of HESPs in Flues 7, 8, and 9 at PIPP....... 1-5

Table 2-1. Stream Data. ........................................................................................................ 2-3

Table 3-1. Baghouse Design Specifications. ........................................................................ 3-3

Table 3-2. PIPP PRB Coal Analysis. .................................................................................... 3-3

Table 4-1. Major Equipment List.......................................................................................... 4-2

Table 4-2. Typical Particulate Loading at Presque Isle. ....................................................... 4-3

Table 4-3. Test Bag Materials............................................................................................... 4-6

Table 4-4. Ductwork Sizing Summary. .............................................................................. 4-23

Table 5-1. Summary of Equipment, Balance-of-Plant, and Engineering Costs. .................. 5-1

Table 5-2. Additional Equipment Costs since Startup.......................................................... 5-4

Table 6-1. Summary of Operating and Maintenance Costs.................................................. 6-1

Table 6-2. Summary of Startup Costs................................................................................... 6-2
vii

LIST OF FIGURES

Figure 1-1. Organizational Chart. ........................................................................................ 1-2

Figure 1-2. TOXECONTM Configuration. ............................................................................ 1-3

Figure 2-1. Process Flow Diagram. ...................................................................................... 2-3

Figure 4-1. Schematic of Thermo Prototype Mercury CEM. ............................................. 4-29
viii

LIST OF ABBREVIATIONS

A/C Air-to-cloth ratio

acfm Actual cubic feet per minute

ACI Activated carbon injection

A/E Architect/Engineer

BOP Balance-of-plant

CCPI Clean Coal Power Initiative

CEM Continuous emissions monitor

COHPAC® Compact Hybrid Particulate Collector

DCS Distributed control system

DOE Department of Energy

EPRI Electric Power Research Institute

ESP Electrostatic precipitator

gr/acf Grains per actual cubic foot

HESP Hot-side electrostatic precipitator

Hg Mercury

HP Horsepower

HVAC Heating ventilation air conditioning

ID Induced draft

I/O Input/output

lb/hr Pounds per hour

LOI Loss on ignition

MCC Motor control center

MMacf Million actual cubic feet

MW Megawatts

NEP National Energy Policy

NEPA National Environmental Policy Act

NETL National Energy Technology Laboratory

NOx Oxides of nitrogen

NFPA National Fire Protection Association

O2 Oxygen

O&M Operation and Maintenance
ix

OEM Original equipment manufacturer

PAC Powdered activated carbon

PIPP Presque Isle Power Plant

PM Particulate matter

ppm Parts per million

PPS Polyphenylene sulfide

ppt Parts per trillion

PRB Powder River Basin

psig Pounds per square inch gauge

RATA Relative Accuracy Test Audit

RIO Remote I/O

rpm Revolutions per minute

scfm Standard cubic feet per minute

SO2 Sulfur dioxide

T/R Transformer Rectifier

VAC Volts alternating current

VIV Variable inlet vane

WAPC Wheelabrator Air Pollution Control

” w.c. Inches of water column
x

GLOSSARY OF TERMS

The following information provides the reader with an introduction to common terminology 

related to fabric filters and the TOXECONTM technology.

Pressure Drop/Drag – Pressure drop and drag are both used to monitor the permeability of 

the filter and filter cake. Pressure drop is a direct measurement of the pressure difference 

across the fabric filters. Drag is a calculated number that normalizes pressure drop to flow 

by dividing pressure drop by the air-to-cloth (A/C) ratio. These values are a function of inlet 

grain loading, filtering characteristics of the particulate matter, flue gas flow rate, and time 

between cleaning. The particulate matter, or dust, adhering to the outside of the bags is 

usually referred to as “cake,” which acts as a filtering medium and presents a resistance to 

flow. A greater inlet loading or longer bag cleaning cycle time will result in deposition of a 

thicker cake collected on the bag surface. A thicker cake on the surface results in a higher 

pressure drop. Excessive pressure drop is undesirable because of the energy required to 

overcome it. Fans need to be sized to compensate for this expected pressure drop and higher 

pressure drops require larger fans and subsequently more horsepower. Once a system is 

designed and in operation, excessive pressure drop is a problem if the pressure drop exceeds 

the fan capacity. In this case, a generating unit becomes load limited due to insufficient fan 

capacity to run at full load. In addition, the cleaning system needs to run more often, which 

consumes additional compressed air motor energy, and the bag life is shortened due to 

additional cleaning cycles. Bags flex when they are cleaned because they are made of a 

fabric material, and this flexing eventually causes a failure of the material (McKenna, 1989).

Cleaning Frequency – Pressure drop and drag are controlled in a baghouse by the cleaning 

frequency. Higher inlet loading causes increased pressure drop and subsequent increased 

cleaning frequency. Cleaning cycles are initiated by a set pressure drop value for the system. 

When the system pressure drop increases to this point a cleaning cycle is initiated (see 

“Cleaning Modes” below). Cleaning frequency increases with the increased particulate 

loading from sorbent injection.
xi

Opacity/Emissions – Cleaning frequency and particulate matter characteristics can affect 

collection efficiency across the baghouse. Most emissions occur immediately following 

cleaning, so increasing the cleaning frequency can increase outlet emissions. The emissions 

could also increase if the particulate does not form a high-efficiency filter, but tends to work 

through the fabrics.

Air-to-Cloth (A/C) Ratio – The ratio between flue gas flow (acfm) and total fabric surface 

area (ft2), expressed in ft/min. A lower A/C ratio indicates a larger, more conservative 

design. Typically, pulse-jet fabric filters are designed with A/C ratios between 3 and 

4 ft/min. COHPAC and TOXECONTM applications target a higher, more economical 

design between 5 and 8 ft/min.

Cleaning Modes – Pulse-jet fabric filters are generally cleaned with either “online” or 

“offline” cleaning. In either case, cleaning is usually initiated when a predetermined pressure 

drop or drag setpoint is reached. In the case of offline cleaning, when the setpoint is reached, 

inlet and/or outlet dampers close, isolating a single compartment. This compartment is then 

systematically pulsed, row-by-row, until it has been entirely cleaned. The isolating dampers 

are then opened and flue gas reenters the compartment. In the case of online cleaning, when 

the setpoint is reached single rows are cleaned around the various compartments without any 

isolation. Because flue gas continues to flow through the bags being cleaned during online 

cleaning, the degree of cleaning is reduced. The benefits of online cleaning are that there is 

not a pressure spike (from isolating a compartment) and there is not a sudden very clean area 

in the fabric filter. When a compartment is cleaned offline, it creates a “hole” in the fabric 

filter, which can temporarily reduce particulate control and potentially mercury control.
xii

EXECUTIVE SUMMARY

This document provides a summary of the design efforts involved in the project 

“TOXECONTM Retrofit for Mercury and Multi-Pollutant Control on Three 90-MW CoalFired Boilers” that was completed on September 30, 2009. This U.S. Department of Energy 

(DOE) Clean Coal Power Initiative (CCPI) project was based on a cooperative agreement 

between We Energies and the DOE Office of Fossil Energy’s National Energy Technology 

Laboratory (NETL) to design, install, evaluate, and demonstrate the EPRI-patented 

TOXECONTM air pollution control process. Project partners included Cummins & Barnard

(C&B), ADA Environmental Solutions (ADA-ES), and the Electric Power Research Institute

(EPRI).

The primary goal of this project was to reduce mercury emissions from three 90-MW units 

that burn Powder River Basin coal at the We Energies’ Presque Isle Power Plant in 

Marquette, Michigan. Additional goals were to reduce nitrogen oxide, sulfur dioxide, and 

particulate matter emissions; allow reuse and sale of fly ash; advance commercialization of 

the technology; demonstrate a reliable mercury continuous emission monitor (CEM) suitable 

for use at power plants; and demonstrate recovery of mercury from the sorbent.

The project was chosen for award in 2003 with Budget Period 1 taking place in 2004 and 

early 2005. Budget Period 2 of the project began in 2005 and came to a close in September 

2009. Budget Period 1 included activities of project definition, design and engineering, 

prototype testing, major equipment procurement, and foundation installation. Budget 

Period 2 activities included CEMS demonstration, TOXECONTM erection, TOXECONTM 

operation, and carbon ash management demonstration.

Technology Overview

We Energies and the project team designed, installed, evaluated, and operated an integrated 

emissions control system for mercury and particulate matter that treated the flue gases of 

three 90-MW subbituminous coal-fired units. This was the first commercial full-scale 

TOXECONTM demonstration using activated carbon injection (ACI) for mercury removal. 

TOXECONTM is an EPRI-patented process (U.S. Patent 5,505,766) for removing pollutants 
xiii

from combustion flue gas by injecting sorbent between an existing particulate collector and a 

fabric filter (baghouse) installed downstream for control of toxic species. At Presque Isle, 

the existing collectors were hot-side electrostatic precipitators (HESP). The TOXECONTM 

configuration, shown in Figure 1, allowed for separate treatment or disposal of the ash 

collected in the hot-side ESP (99% or greater) and the ash/sorbent collected in the 

TOXECONTM baghouse, unlike other configurations that have ACI upstream of the 

particulate control device.

Figure 1. Process Flow Diagram.

The TOXECONTM system at Presque Isle consisted of a modification of the flue gas 

ductwork from each of the three units into a single duct that led to the new baghouse. A

single duct exited the baghouse and then split into three individual branches with three new 

booster fans. The ducts exiting the booster fans were then recombined into a single duct 

back to the existing stack where the combined duct was again separated into three branches 

that supplied the three existing individual unit stack flues. The combined design condition 

FABRIC FILTER

ACI 

SILO

ID FAN

HESP

UNIT 9

HESP

UNIT 8

HESP

UNIT 7

COAL

AIR 

HEATER

AIR 

HEATER

AIR 

HEATER

COAL

COAL

STACK

ID FAN

BOOSTER 

FAN

BOOSTER 

FAN

CEM

CEM

TOXECON

Retrofit*

*Also includes inlet 

CEMS and ACI 

Injection System

PAC/Ash
xiv

for the three-unit flue gas system flow was 1,200,000 acfm @ 350 F with approximately 14” 

w.c. of pressure drop from the ID fan discharges to the stack.

Also included in the TOXECONTM system was the PAC storage silo and injection system;

and a new ash storage silo and ash unloading system.

Design and Engineering Considerations

A full evaluation of the commercial potential of TOXECONTM required long-term data on an 

installation that was specifically designed for both particulate control and sorbent injection. 

The installation also needed to have the flexibility to handle potential variability in 

particulate loading due to mercury control parametric and optimization testing, as well as 

increased loading from injecting sodium sorbents for the sulfur dioxide reduction tests. The 

design specifications for the pulse-jet style baghouse are listed in Table 1.

Table 1. Baghouse Design Specifications.

Item Specification

Total Compartments 10

Bags per Compartment 648

Total Bags in Baghouse 6480

Air-to-Cloth Ratio (gross) 5.2

Design Gas Volume 1,200,000 acfm

Cleaning Method On-line

The bag fabric chosen was 18 oz/yd2, 2.7 denier PPS (polyphenylene sulfide fiber) felt. The 

bags were 26 feet long and 5 inches in diameter. Several test bags made from newer 

materials were also installed and tested throughout the demonstration project.

Norit Americas DARCO® Hg and Hg-LH were the two primary sorbents tested during the 

project. The activated carbon injection system installed was designed by ADA-ES and 

equipment was provided by Norit Americas. The design injection rate was 216 lb/hr 

(3 lb/MMacf total) and there were three injection trains (one per duct). The maximum 

capacity of the injection system was 600 lb/hr. The silo storage capacity was 4,490 cu ft, and 

depending upon the PAC density, could hold 80–100 tons of sorbent. Several other 
xv

experimental and/or imported carbons from Norit and ADA-ES were also tested full-scale 

using temporary injection equipment.

In addition to the primary air pollution control system, balance-of-plant design considerations 

were addressed. These include booster fans, compressed air system, ash handling system, 

ductwork, electrical, and instrumentation and controls. A task in the project was devoted to 

advancing a monitoring system that would reliably measure mercury in flue gas from coalfired power plants. Design considerations for the mercury continuous emissions monitors, 

including reporting and monitoring needs were also included.

Modifications to the Installation

After the construction was complete and throughout the demonstration portion of the project, 

several modifications to the equipment and structures were required.

Baghouse Modifications

Several modifications were incorporated to gain more optimal temperature control in the 

baghouse and booster fan building including larger ventilation fans and louvered windows at 

the top of the baghouse, additional walls in the upper and lower baghouse areas to block flow 

of hot air from the fan building, additional louvered windows at the booster fan inlet gate 

level and modified temperature controls to achieve better heat control, and additional walls 

and larger heaters in the lower baghouse area.

Additional modifications were added to improve structural integrity and maintenance access: 

the baghouse covers were rebuilt with checker plate and angle iron, and additional stiffeners 

were added across the width of the covers to improve strength; a redesigned lifting spreader 

for the covers was provided to keep from bending the covers when trying to open under 

negative pressure; platforms were added to access the booster fan outlet; and ice breaks were 

added to the top of the baghouse vent louvers.

Ash Handling System Modifications

Excessive dusting was occurring during the use of the wet unloading system, especially when 

starting the pin mixer. Several modifications were incorporated into the original pin mixer. 

Finally, a larger pin mixer had to be installed because the modifications still did now allow 
xvi

for a dust-free unloading process. This helped to eliminate the dusting and equipment issues 

seen during the demonstration. The main differences between the original mixer and the new 

mixer were additional fogging and spray nozzles, and the motor was increased from 7.5 HP

to 10 HP, thereby increasing the mixer speed at 60 Hz motor frequency from 76 rpm to 

100 rpm.

Additional modifications were made to improve flow of the PAC/ash mixture into the pin 

mixer. A new rotary valve was added to replace the original butterfly valve and, although 

fluidization at the silo discharge was normally not required, the original fluidization valves 

were replaced by three large air cannons.

There were other modifications to improve operability of the ash unloading system. A

rubber skirt was added to the wet unloading spout to improve dust control, the sequencing of 

the exhauster and system relief valves was optimized to allow dust to be purged from 

vacuum relief piping before purging, an extension to the unloading shelter to the east of the 

silo was installed. This reduced the wind tunneling effect and protected the area from the

elements.

Ductwork Modifications

Two inches of insulation was added to all expansion joints on the baghouse ductwork 

(approximately 28 places) to minimize corrosion due to flue gas condensation on cold spots 

in and around the joints.

Access Platform Additions

Four access platforms were added to the baghouse discharge ducts. Three platforms (one for 

each unit) were located underneath the ductwork at the 90 elbows just upstream of the 

diverter damper. The fourth additional platform was added on top of the Unit 8 ductwork to 

provide access to the baghouse.

Equipment and Installation Costs

The costs of equipment and installation for the TOXECONTM and balance-of-plant systems 

were $34.6 million, including the engineering effort. The cost of the additions and 

modifications after construction were $413,500.
1-1

1.0 PROJECT OVERVIEW

1.1 Purpose of the Public Design Report

This Public Design Report provides non-proprietary information on the performance and 

economics of the TOXECONTM air pollution control system installed at We Energies’

Presque Isle Power Plant (PIPP) located in Marquette, Michigan, under U.S. Department of 

Energy Cooperative Agreement No. DE-FC26-04NT41766. This report describes the design 

and equipment associated with the TOXECONTM multi-pollutant system. This is the second 

of two final documents describing the installation at PIPP. The first document is the Project 

Performance and Economics Report (We Energies, 2009). A Preliminary Design Report was 

issued after the completion of the construction phase (We Energies, 2006), and this document 

is an expanded update of that report.

1.2 Brief Description of the Project

The project described in this report was conducted under the Department of Energy’s (DOE) 

Clean Coal Power Initiative (CCPI). The CCPI is an industry/government cost-shared 

partnership to implement clean coal technologies.

The CCPI was initiated in 2002 with a goal of accelerating commercial deployment of 

advanced technologies to ensure the United States has clean, reliable, and affordable 

electricity. The CCPI builds upon the advancements made by previous and continuing clean 

coal research and ensures the ongoing development of advanced systems for commercial 

power production.

1.2.1 Project Schedule

The project was selected for award in early 2003 with Budget Period 1 taking place in 2004 

and early 2005. Budget Period 2 of the project began in 2005 and came to a close in 

September 2009. Budget Period 1 included activities of project definition, design and 

engineering, prototype testing, major equipment procurement, and foundation installation. 

Budget Period 2 activities included CEMS demonstration, TOXECONTM erection, 

TOXECONTM operation, and carbon ash management demonstration.
1-2

1.2.2 Project Organization

The project team included We Energies, ADA Environmental Solutions (ADA-ES), 

Cummins & Barnard (C&B), and the Electric Power Research Institute (EPRI). We Energies 

provided and operated the demonstration site, as well as provided project management, 

environmental permitting, and reporting. ADA-ES was the project management interface 

with DOE’s National Energy Technology Laboratory (NETL), and was responsible for the 

design of the mercury control system, design of the mercury monitoring system, 

demonstration testing of the overall process, and reporting. Wheelabrator was responsible 

for the design and construction of the baghouse, support of baghouse installation, and 

provided startup support under a subcontract to We Energies. C&B provided architectural 

and engineering services, construction management, design and specification of equipment, 

equipment installation, and startup training for plant operators. EPRI provided technical 

advice to We Energies. Figure 1-1 is a simplified organizational chart for the project.

Figure 1-1. Organizational Chart.

DOE/NETL

Program Manager

We Energies

Program Manager

ADA-ES

Manage 

Demonstration

ADA-ES

CEM Development

ADA-ES 

TOXECON

ADA-ES/We Energies

Ash Management

Cummins & Barnard

Engineering/Construction

We Energies/ADA-ES

Environmental 

Permitting

We Energies

Construction 

Management

Wheelabrator

Baghouse

EPRI

Technical Advisor

ADA-ES

Financial, Contracts, Reporting
1-3

1.2.3 Project Description

We Energies and the project team designed, installed, evaluated, and operated an integrated 

emissions control system for mercury and particulate matter that treated the flue gases of 

three 90-MW subbituminous coal-fired units. This was the first commercial full-scale 

TOXECONTM demonstration using activated carbon injection (ACI) for mercury removal. 

TOXECONTM is an EPRI-patented process (U.S. Patent 5,505,766) for removing pollutants 

from combustion flue gas by injecting sorbent between an existing particulate collector and a 

fabric filter (baghouse) installed downstream for control of toxic species. At Presque Isle, 

the existing collectors were hot-side electrostatic precipitators (HESPs). The TOXECONTM 

configuration, shown in Figure 1-2, allows for separate treatment or disposal of the ash 

collected in the HESP (99% or greater) and the ash/sorbent collected in the TOXECONTM 

baghouse.

Figure 1-2. TOXECONTM Configuration.

The project advanced the ancillary processes that are significant to mercury control, such as 

mercury measurement technology and waste minimization. As a secondary priority, the 

project also investigated SO2 and NOx control after mercury control issues had been 

addressed.

Pulverized 

Coal Boiler

Air 

Heater

Stack

TOXECONTM

Coal

Sorbent 

Injection

Baghouse

HESP
1-4

1.2.4 Project Location

The project took place at We Energies’ Presque Isle Power Plant (PIPP) located in 

Marquette, Michigan. PIPP had nine boilers and this project applied to Units 7, 8, and 9. 

Each of the 90-MW units had a HESP as the primary particulate matter (PM) control device. 

The exhausts from the three HESPs were ducted into individual flues of a common stack. 

The project involved controlling the emissions from the three units using a single baghouse. 

Integrating the three units into one project and structure provided significant cost savings 

over treating the units separately, and optimized the use of space.

The TOXECONTM process was ideal for PIPP because the existing HESP exhausts benefitted 

from the additional PM control, especially during startup and shutdown. Also, the existing 

HESPs used for PM control did not have the ability to remove mercury from the flue gas, and 

injection of powdered activated carbon (PAC) into these HESPs was not feasible due to the 

high flue gas temperatures. The TOXECONTM process also allowed We Energies to 

continue to sell its fly ash from the HESPs because the carbon was injected downstream of 

these units.

The PIPP Units 7, 8, and 9 were placed in service in 1978, 1978, and 1979 respectively by 

Upper Peninsula Power Company to meet the needs of Cleveland-Cliffs Iron Co. Wisconsin 

Electric purchased the plant in 1988. Refer to Appendix C for plant schematics.

The boilers were Riley Turbo units rated for a maximum continuous capacity of 

615,000 lb/hr steam flow at 1625 psig superheater outlet pressure and 1005 oF. Reheater 

steam flow was 555,000 lb/hr at 390 psig and 1005 oF. Each unit was fired by two 10’ X 13’ 

Riley ball tube mills and directional flame burners.

The precipitators were designed and built by Joy-Western and were designed as HESPs with 

an operating range of 565–745 oF. The units were two chambers wide and were a weighted 

wire unit consisting of six mechanical fields per chamber and twelve electrical frames, six 

per chamber powered by six full-wave transformer/rectifiers (T/R). The units were designed 

to collect fly ash from a pulverized coal boiler with a gross rating of 93 MW and a design gas 

volumetric flow rate of 530,000 acfm. The design collection efficiency was 99.20%.
1-5

Typical flow rates and gas components in the flue gas exiting the HESPs of Units 7–9 are 

shown in Table 1-1.

Table 1-1. Flue Gas Composition Downstream of HESPs in Flues 7, 8, and 9 at PIPP.

Characteristic Flue 7 Flue 8 Flue 9

Gas Volumetric Flow Rate, acfm 377,719 375,014 335,439

Average Gas Temperature, oF 364.6 344.8 366.6

Flue Gas Moisture, % by volume 12.1 13.3 12.7

Average % CO2 by volume, dry basis 12.8 13.0 13.0

Average % O2 by volume, dry basis 6.2 6.0 6.0

Filterable PM, lb/hr 15.13 9.99 20.35

NOx, lb/hr 407.8 410.5 406.8

SO2, lb/hr 461.9 464.7 474.7

Mercury, ppm dry (Average Units 7–9) 0.062 0.062 0.062

The combustion process was controlled by an Emerson distributed control system with a 

SmartProcess® Combustion Optimization software package to optimize NOx and loss on 

ignition (LOI).

PIPP burned Powder River Basin (PRB) subbituminous coal in Units 7–9. Analysis of the 

coal sampled at PIPP during the project showed a mercury concentration of 0.062 μg/g on a 

dry basis. PRB coal was supplied by several mines in Wyoming and Montana (dependent on 

the price of the fuel) and shipped by rail to Superior, Wisconsin, where it was then loaded 

onto a lake boat for delivery to PIPP.

1.3 Objectives of the Project

The primary goal of this project was to reduce mercury emissions from three 90-MW units at 

the We Energies Presque Isle Power Plant. Additional objectives were to reduce nitrogen 

oxide (NOx), sulfur dioxide (SO2), and particulate matter (PM) emissions; allow for reuse 

and sale of fly ash; develop and demonstrate a reliable mercury continuous emissions 

monitoring system (CEMS) suitable for use in the power plant environment; and demonstrate 
1-6

methods for sorbent regeneration and/or by-product reuse. This demonstration provided for 

the use of a novel multi-pollutant control system to reduce emissions of mercury and other 

air pollutants while minimizing waste from a coal-fired power generation system.

The specific objectives of this project were to demonstrate the operation of the TOXECONTM 

multi-pollutant control system and achieve:

90% mercury removal from flue gas through activated carbon injection.

An evaluation of the potential for 70% SO2 control and trim control of NOx from flue 

gas through sodium-based or other novel sorbent injection.

Reduced PM emission through collection by the TOXECONTM baghouse,

Recovery of 90% of the mercury captured in the sorbent.

100% availability for utilization of fly ash collected in the existing electrostatic 

precipitator.

Demonstration of a reliable, accurate mercury CEMS suitable for use in the power 

plant environment.

A successful system integration and optimization of TOXECONTM operation for 

mercury and multi-pollutant control.

1.4 Significance of the Project

The CCPI demonstration of the TOXECONTM process was important to the industry because 

it provided long-term operational experience directly applicable to power plants that burn 

western subbituminous coal. With its proven ability to reduce mercury emissions, the 

process offers a significant benefit to operators of subbituminous-fueled units in that mercury 

in flue gas produced by these units exists primarily in the elemental vapor form that is 

insoluble in water and, as such, will pass through most types of other air pollution control 

devices. As a result of this project, the TOXECONTM process is in the position to become a 

leading mercury control choice for western coals, especially for units that use a hot-side 

electrostatic precipitator.
1-7

A primary benefit of this project was the long-term demonstration of 90% mercury removal 

from the stack emissions. The project also demonstrated emission control of particulate 

matter and sulfur dioxide. In addition, the process is able to maintain the beneficial use of 

HESP fly ash as a concrete additive.

A very important additional benefit has been identifying and solving the technical hurdles as 

they were discovered. One of the most notable issues was the overheating and autoignition 

of the high carbon ash in the baghouse hoppers. The subsequent investigation into the 

mechanism and development of operational guidelines has proven to be useful to other 

utilities using the TOXECONTM configuration. Optimization testing also provided important 

data on reducing sorbent costs and maximizing the life of the bags in the baghouse.

The project was able to significantly reduce the rate of carbon injection needed for achieving 

an average 90% mercury removal rate. The results of numerous test runs pointed out the 

importance of various factors that impacted mercury removal efficiency. These factors 

included the temperature of the flue gas, the amount of time PAC remained on the bags, the 

amount of PAC on the bags, and the amount of carbon in the fly ash. The result led to a 

revised control scheme for cleaning the baghouse that reduced operating costs while not 

impacting emissions or maintenance costs.

1.5 DOE's Role in the Project

The TOXECONTM project is part of the DOE’s Clean Coal Power Initiative, which is an 

industry/government cost-shared partnership. Under the CCPI, the DOE provides up to 50% 

of the funding for the projects. The total cost share for this project was just under $48 

million with the DOE contributing about $24 million and We Energies contributing about 

$24 million.

In 2003, a management plan was prepared to provide a suitable strategy for tracking project 

progress at the task level using an Earned Value Management system. The management plan 

included final work breakdown structure, final statement of project objectives, schedule 

baseline, cost baseline, technology baseline, and management controls. As part of the 

management plan, the DOE had oversight of the project while We Energies communicated 
1-8

project results to DOE to keep DOE fully informed of all aspects of the project. We Energies 

provided quarterly Technical Progress Reports summarizing technical progress, quarterly 

Cost Status Reports summarizing financial status, and quarterly Schedule Status Reports 

summarizing schedule status.

The extended project team including the DOE, EPRI, We Energies, and ADA-ES personnel 

participated in weekly phone meetings to coordinate project activities and to discuss relevant 

project management and technical issues. In this way, all participants including the DOE 

were able to provide value-added input to the success of the project.
2-1

2.0 TECHNOLOGY DESCRIPTION

2.1 Brief Description of the Technology Being Used

Injecting a sorbent such as PAC into the flue gas represents one of the simplest and most 

thoroughly studied approaches to controlling mercury emissions from coal-fired boilers 

(Government Accountability Office, 2005). The gas-phase mercury in the flue gas contacts 

the sorbent and attaches to its surface. The sorbent with attached mercury is then collected 

by the existing particulate control device, either an electrostatic precipitator (ESP) or in the 

case of a TOXECONTM technology, a fabric filter. Over the past several years, the results 

from numerous full-scale evaluations of ACI for mercury removal indicate that activated 

carbon is a viable technology for mercury control on many coal-fired power plants (Durham, 

2003; Bustard, et al., 2001).

For some plants, one of the disadvantages of injecting activated carbon is its impact on the 

salability of ash for making concrete. Tests have shown that the activated carbon interferes 

with chemicals used in making concrete (Bustard, 2003). This has also been confirmed 

under the project described in this report. One straightforward, cost-effective approach to 

achieving high mercury removal without contaminating the fly ash is the use of the EPRI 

TOXECON process. With the TOXECONTM configuration, the ash collected upstream of 

the carbon injection remains acceptable for sale. The downstream fabric filter provides an 

effective mechanism for the activated carbon to have intimate contact with vapor-phase 

mercury, resulting in high levels of mercury control at relatively low sorbent injection rates.

The advantages of the TOXECON configuration are:

Sorbents are mixed with a small fraction of the ash (the less than 1% that exits the 

primary PM device), which reduces the impact on ash reuse and waste disposal.

Full-scale field tests have confirmed that fabric filters require significantly less sorbent 

than ESPs to achieve similar mercury removal efficiencies (Bustard, 2004). This was 

also confirmed on the CCPI project.
2-2

Outage time can be significantly reduced with TOXECON systems in comparison to 

the major ESP rebuilds/upgrades that might be required to handle the increased 

loading and greater collection difficulty of the injected carbon. Since the 

TOXECONTM unit is added downstream of the ESP, experience shows that it can be 

built, installed, and checked while the ESP is still in full operation, thus keeping 

outage time to a minimum.

Baghouse types include shaker-cleaned, reverse-air-cleaned, pulse-jet-cleaned, and 

sonic-cleaned. A pulse-jet-cleaned baghouse was chosen for this application. Pulse 

jet baghouses use fabric filtration media shaped like tubes called bags, which are 

usually 4–6 inches in diameter and 10 to 26 feet long, to remove the particulate matter 

from the flue gas stream. The bags are mounted (hung) from a tube sheet and the gas 

stream flows from the outside of the bag through the bag, depositing particulate matter 

on the outside of the bag. A wire cage inside the bag supports the bag during filtration 

and cleaning. The particulate matter is removed from the bags by a cleaning system 

that employs compressed air (systems are designed to use compressed air from 30–

120 psig) to back flush the bags (McKenna, 1989).

2.1.1 Proprietary Information

There is no proprietary information listed in this report.

2.2 Overall Block Flow Diagram

Figure 2-1 shows a simplified process flow diagram showing the TOXECONTM retrofit 

equipment. The inlet CEM probes and lines were integrated into the three ducts upstream of 

the ID fans. The ACI lances were installed in each duct downstream of the ID fans and just 

before the ducts’ exit from the building envelope. Mercury data was taken upstream of PAC 

injection and downstream of the baghouse, and, occasionally, at the stack.
2-3

Figure 2-1. Process Flow Diagram.

Table 2-1 shows some of the process stream data for the TOXECONTM baghouse. Many 

stream components remained unchanged, such as gas flow rate and all major flue gas 

components. Mercury concentration in the flue gas was reduced by an average of 90%. 

Particulates were significantly reduced through the baghouse also. The flue gas temperature 

was reduced slightly as it passed through the baghouse. More detailed information can be 

found in Section 4.1 of this report.

Table 2-1. Stream Data.

Stream Parameter Baghouse Inlet Baghouse Outlet TOXECONTM Ash

Volumetric Flow Rate 1,200,000 acfm 1,200,000 acfm ----

Mercury Concentration 5.5–7.0 ug/m3< 1 ug/m340–80 ppm

Temperature 320–375 oF 5 oF below inlet ----

Particulates 0.0116 gr/acf 0.0016 gr/acf Approx. 200 lb/hr

PAC/ash mixture

Loss on Ignition (LOI) < 1% ---- 40–50%

FABRIC FILTER

ACI 

SILO

ID FAN

HESP

UNIT 9

HESP

UNIT 8

HESP

UNIT 7

COAL

AIR 

HEATER

AIR 

HEATER

AIR 

HEATER

COAL

COAL

STACK

ID FAN

BOOSTER 

FAN

BOOSTER 

FAN

CEM

CEM

TOXECON

Retrofit*

*Also includes inlet 

CEMS and ACI 

Injection System

PAC/Ash
3-1

3.0 PROCESS DESIGN CRITERIA

3.1 Design Recommendations for Presque Isle TOXECON

A full evaluation of the commercial potential of TOXECONTM required long-term data on an 

installation that was specifically designed for both particulate control and sorbent injection. 

The installation also needed to have the flexibility to handle potential variability in 

particulate loading, as was planned for the SO2 reduction testing with sodium sorbents, and 

between the short-term parametric and long-term testing periods.

Operational experience from the only two existing COHPAC fabric filters in the U.S. at the 

time this project was in the design phase (Gaston Units 2 and 3 and TXU’s Big Brown 

Units 1 and 2) and test results from bench-, pilot-, and full-scale tests provided a good basis 

for design recommendations (Miller, et al., 1999; Bustard, et al., 2001). These

recommendations included:

Air-To-Cloth Ratio – The Gaston tests showed that TOXECON units designed at 

lower A/C ratios than COHPAC were capable of high, 90%, mercury removal (short 

term). The recommendation for this TOXECON fabric filter, based on the low A/C 

ratio tests at Gaston, was for a maximum design gross A/C ratio of 6.0 ft/min.

Fabric – The most accepted fabric for pulse-jet fabric filters installed on coal-fired 

power plants is made from a polyphenylene sulfide fiber, commonly referred to 

worldwide as PPS. PPS felted material is currently available under the trade names 

TORCON and PROCON . The original equipment manufacturer (OEM) fabric for 

the four existing COHPAC fabric filters was an 18 oz/yd2, 2.7 denier PPS felt. 

Denier is a unit used to measure the fineness of fabric, equal to the mass in grams of 

9,000 meters of thread. For example, 9,000 meters of 15 denier nylon, used in nylon 

stockings, weighs 15 g/0.5 oz, and in this case the thickness of thread would be 

0.00425 mm/0.0017 in.

In recent years, advancements have been made with higher permeability fabrics that 

operate at lower pressure drop. A high permeability fabric made with a 7.0 denier 
3-2

fiber has replaced the OEM fabric at both Gaston and Big Brown. The 2.7 denier 

fabric was recommended for PIPP because:

- TOXECON was designed at a lower A/C ratio than COHPAC and did not 

require higher fabric permeability.

- Field observations indicate that there may be higher particle penetration through 7.0 

denier bags. Although this had not been quantified, it was desirable in this 

demonstration to use a more conservative design.

Sorbent – Norit Americas DARCO® Hg (formerly DARCO®FGD) activated carbon 

had been the benchmark sorbent used in test programs starting as early as 1991. This 

sorbent had a proven record on many different coals, excellent quality control, and 

adequate capacity to supply 20–30 units. DARCO® Hg is made from Texas lignite 

coal, has a mass mean diameter of nominally 17 microns and a bulk density of about 

30 lbs/ft3. Appendix A contains detailed information on DARCO®FGD carbon. 

DARCO®FGD carbon was used at the Gaston plant with excellent mercury removal 

efficiencies (Bustard, et al. 2004). The initial PAC injection concentration was 

3.0 lb/MMacf and was based on the Gaston and EPRI tests described above (Bustard 

et al., 2001; Sjostrom, et al., 2002).

Cleaning – In order to obtain the highest utilization of the activated carbon, it was 

originally desirable to keep the carbon on the bag as long as possible before cleaning. 

With that in mind, online cleaning was recommended. During the demonstration, 

mercury removal data indicated that more frequent cleaning improved mercury control 

by preventing reemission of the mercury from the carbon particles.

3.2 Baghouse Design Specifications

The design specifications for the baghouse are listed in Table 3-1.
3-3

Table 3-1. Baghouse Design Specifications.

Item Specification

Total Compartments 10

Bags per Compartment 648

Total Bags in Baghouse 6480

Air-to-Cloth Ratio (gross) 5.2

Design Gas Volume 1,200,000 acfm

Cleaning Method On-line

3.3 Coal Analysis

Presque Isle Units 7–9 bur PRB subbituminous coal. A typical coal analysis is shown in 

Table 3-2.

Table 3-2. PIPP PRB Coal Analysis.

Parameter Results

(as received)

Proximate

Water 26.52%

Volatiles 30.46%

Fixed Carbon 38.45%

Ash 4.57%

Ultimate

Carbon 52.49%

Hydrogen 3.65%

Oxygen 12.3%

Nitrogen 0.75%

Sulfur 0.28%

Chlorine 0.01%

Water 25.85%

Ash 4.64%

High Heating Value 9052 Btu/lb
4-1

4.0 DETAILED PROCESS DESIGN

4.1 General Arrangement

The TOXECONTM system at Presque Isle consisted of a modification of the flue gas 

ductwork from each of the three units into a single duct that led to the new baghouse. The 

single duct exited the baghouse and was then split into three individual branches with three 

new booster fans. The ducts exiting the booster fans were then recombined into a single duct 

back to the existing stack where the combined duct was again separated into three branches 

that supplied the three existing individual unit stack flues. The combined three-unit flue gas 

system flow was 1,200,000 acfm @ 350 F with approximately 14” w.c. of pressure drop

from the ID fan discharges to the stack.

Also included in the TOXECONTM system were the PAC storage silo and injection system 

and a new ash storage silo.

Refer to Appendix C general arrangement drawings 4937-CGA-M1000, 4937-CGA-M1001, 

4937-CGA-M1002, 4937-CGA-M1003, and 4937-CGA-M1004 for a layout of the project. 

Drawing 4937-CBA-M0112 is a piping and instrumentation diagram of the flue gas system.
4-2

4.2 Equipment List

Table 4-1 lists all significant items of process equipment.

Table 4-1. Major Equipment List.

Item 

No.

Item Name Number Vendor

In Use Spare

1 Baghouse 1 0 Wheelabrator

2 Electrical Equipment n/a n/a Various

3 Controls (Including Enclosure) n/a n/a Emerson

4 Air Compressor/Dryer 1 1 Sullair

5 ID Booster Fans 3 0 Flakt-Woods

6 Ash System 1 0 United Conveyor

7 PAC System 1 0 Norit

8 Dampers n/a n/a Wahlco

9 Expansion Joints n/a n/a PAPCO

10 Ductwork and Structural Steel n/a n/a Merrill, Cives

11 Mercury Continuous Emissions Monitors 2 0 Thermo Fisher

Design conditions were:

1) Unit capacity of 270 MW.

2) Air/cloth = 5.2 ft/min.

3) Flue gas flow rate of 1,200,000 acfm.

4.3 Baghouse Design

The mercury concentration in the ducts exiting the HESPs at Presque Isle was measured in 

2005 using both the Thermo Electron (now Thermo Fisher) CEM and the Sorbent Trap 

Method (STM) and was found to be around 6 μg/dNm3(Sjostrom, 2005). This was the 

mercury concentration typically entering the baghouse along with the 1% of the total ash. 

4.3.1 Inlet Particulate Loading

The original particulate loading was based on the collection rate of fly ash (200 lb/hr max) 

and the injection rate of PAC (450 lb/hr max), which included not only the initial PAC 
4-3

collection, but any recycled material that might be collected in later tests. The total 

maximum baghouse loading for fly ash/PAC was 650 lb/hr (0.325 tons per hour). Particulate 

tests were performed at the stack at Presque Isle in June 2005. Table 4-2 shows the 

particulate loading for Presque Isle and a comparison to the conditions during testing at 

Gaston.

Table 4-2. Typical Particulate Loading at Presque Isle.

Location Particulate Loading

(gr/acf)

Carbon Injection

(gr/acf)

PIPP Flue 7 0.0047 -

PIPP Flue 8 0.0031 -

PIPP Flue 9 0.0071 -

PIPP Estimated Inlet (Total 7–9) 0.0050 0.021

Gaston – Low Load 0.0062 0.0063–0.014

Gaston – High Load, Mid-Range Values 0.07–0.14 0.0025

4.3.2 Type of Baghouse

A pulse jet style baghouse was selected for Presque Isle. This style reflected a typical 

industry standard and required a small footprint area for the congested Presque Isle site. 

Based on a competitive bid process, a baghouse provided by Wheelabrator Air Pollution 

Control was selected. The baghouse was appropriate for the Presque Isle TOXECONTM 

project since baghouses of this type have been installed successfully in other power plant 

applications where the flue gas flow and particulate loading were much higher than the 

conditions at Presque Isle.

4.3.3 Air-to-Cloth Ratios

Low flow tests performed at Gaston showed that a baghouse configuration utilizing an A/C 

ratio of less than 6 ft/min was recommended for new TOXECONTM units (Bustard, et al., 

2004). These tests also showed that a mercury removal over 90% was achievable under these 

conditions. These tests also showed that the outlet mercury concentrations varied from 3.2-
4-4

0.61 μg/Nm3 with an injection concentration of 0.9–3.3 lbs/MMacf, respectively. For PIPP 

to have a 90% removal at an inlet concentration of 6 μg/Nm3or an outlet concentration of 

0.6 μg/Nm3, it was anticipated that the design injection rate of 216 lb/hr (3.0 lb/MMacf) was 

required. Gaston was used as a guide here since no other test data was available. The 

differences in coal composition and gas temperatures between the two sites were substantial. 

Knowing this, the installed excess injection capacity allowed for adequate removal 

considering that the system could inject up to 600 lb/hr (8.3 lb/MMacf). The excess capacity 

also allowed testing of additional sorbents such as recycled PAC injection material.

Based on industry historical experience, test results from Gaston, bag supplier experience, 

the project stated goals, and compartment configuration; an A/C ratio of 5.2 ft/min was 

selected. The net (one compartment out of service) and net-net (two compartments out of 

service) A/C ratios were 6.1 and 6.8 ft/min, respectively.

The volumetric flow of 1,200,000 acfm of flue gas was calculated using heat balance 

software and compared to test data that were taken for air heater performance tests and stack 

emissions tests. The final selection of flow was chosen at 350 F, which was determined to 

be an achievable flue gas temperature considering the historical operational flue gas 

temperatures.

4.3.4 Flue Gas Cooling

A technical concern of this project was the expected range of flue gas temperatures. The air 

preheater on each of the three units deviated significantly from its design such that the gas 

outlet temperature operating range was measured at about 350 °F to 380 °F. This range was 

above the optimal condition for untreated sorbent performance and would likely preclude 

acceptable mercury control with the standard sorbent. Additionally, the high gas exit 

temperature could have a negative impact on unit heat rate and would be a risk to the filter 

bags. As such, efforts were undertaken to reduce the gas outlet temperature using 

sootblowers on the air preheaters in each of the three units. This should have improved the 

efficiency of the air preheaters and increased the cooling of the exit gas from the HESPs. 

Sootblowing tests performed during the demonstration showed a significant reduction in flue 
4-5

gas temperature, allowing 90% mercury removal at relatively low PAC injection rates 

(1.2 lb/MMacf for brominated PAC).

The alternative was to use a spray system to cool the flue gas before treating it with sorbent. 

After completion of the parametric testing and sootblowing tests, the project team determined 

that a spray cooling system was not needed.

4.3.5 Bag Material and Length

4.3.5.1 Base Bag Design

The fabric filter bag material chosen was a polyphenylene sulfide (PPS) material based on 

the flue gas temperature, flue gas analysis, and PAC properties (Appendix A). The base 

design for the TOXECONTM fabric filter was to use PPS fabric bags with the following 

specifications:

Felted, 2.7 denier PPS fabric

Weight of nominally 18 ounces/yd2

Singed on both sides

Scrim material made from 3 ounces/yd2of PPS 

Mullen burst minimum of 500 psi

Maximum temperature for continuous use is 375 oF

Permeability at 0.5” w.c. of 25–40 cfm/ft2

Three of the four baghouse proposals offered a 26-foot bag, while the fourth offered a 20-

foot bag. The final selection was a 26-foot bag with a nominal 5-inch diameter.

4.3.5.2 Alternate Test Bag Materials

The TOXECONTM program also included testing of bags and/or materials provided by other 

manufacturers. A description of the different types of test fabrics installed in Compartment 8 
4-6

can be found in Table 4-3. All test bags were installed in bundle A, or the bundle closest to 

the inlet and outlet plenums. In the case of the Ahlstrom fabric, four approximately 4” x 11” 

swatches were installed in frames in a swatch holder, which was placed on the supporting 

steel above the bags and pulse pipes. Although full-scale bags were preferred for the tests, 

using swatches reduced the risk of premature failures with experimental bags. For 

comparison, four OEM swatches were also installed. Additional test bags and swatches were 

installed and tested throughout the demonstration project. Refer to the Project Performance 

and Economics Report (We Energies, 2009) for more detail.

Table 4-3. Test Bag Materials.

Bag ID Material/Design Benefit Quantity

9065 Dual density Torcon (0.9 

and 2 denier blend on filter 

side, 7 denier on other side)

High Perm on one side, 

high collection efficiency 

on other side

9

1342 P84 Higher temperature, 

higher collection 

efficiency

11

GE/BHA-TEX Scrim-supported PPS felt 

with a BHA-TEX Expanded 

microporous PTFE 

Membrane

Membrane provides 

higher collection 

efficiency and promotes 

light dustcake formation

10

Toray Proprietary material 2

Environmental 

Products and 

Systems, Inc.

PPS fabric Alternate source of PPS 

bags

1

Ahlstrom

GFTS #4406

Armorguard felt, proprietary 

blend

Swatches 

only

4.3.6 Cleaning Method

Baghouses typically clean the filter bags in one of two methods: offline and online cleaning. 

Offline cleaning is accomplished by isolating an individual compartment in the baghouse 

from the flue gas flow prior to cleaning the bags. The bags are then cleaned in the stagnant 

compartment and the dust allowed to settle into the ash hopper before opening the 

compartment to the flue gas flow. Offline cleaning is an efficient method for cleaning the 

bag thoroughly; however, a disadvantage to this method is an increase in velocities and the 
4-7

resulting pressure drop in the other compartments in service when isolating a compartment 

for cleaning. Online cleaning is accomplished without isolating the compartment from the 

flue gas flow. As the bags are cleaned, the normal flue gas flow through the compartment 

would occur. Although the online cleaning method would cause some re-entrainment of the 

dust on the bags, an advantage of the online cleaning method is that it can be accomplished in 

a shorter duration because compartment isolation is not required.

Both cleaning methods clean the filter bags by using pressurized air to blow down the filter 

bags. The burst of compressed air that travels down the filter bag snaps the bag outward, 

causing the agglomerated ash and carbon on the bag to fall off the bag and into the collection 

hopper at the bottom of the compartment.

Online and offline cleaning capabilities were considered and online cleaning was chosen with 

the objectives of maintaining a consistent pressure drop across the baghouse and dust cake on 

the bags. With offline cleaning, all of the bags in a compartment are cleaned at once, 

dislodging the fly ash/activated carbon dust cake and potentially creating an area with lower 

pressure drop and higher flow that does not have adequate sorbent to maintain a high 

mercury removal. During the demonstration program, online cleaning proved to be efficient 

and was chosen for long-term operation. 

The baghouse was configured to clean three rows of filter bags in a compartment, then 

advancing to another compartment. Staggering the cleaning cycle through multiple 

compartments evenly distributed the flow through the baghouse and prevented short circuit 

issues.

During testing it was determined that moisture in the exposed baghouse pulse-air piping may 

have been freezing and restricting air flow during bag cleaning. The plant built a sheet metal 

cover to help insulate this piping from the cold weather (ref: JPG_002, Appendix D).

4.3.7 Compartments

The selection of ten compartments in the baghouse design was based upon the total footprint 

area available at Presque Isle, and the desire to isolate compartments in order to simulate 
4-8

higher A/C ratios. Each compartment had 18 rows and 18 columns, and contained 648 bags. 

In this configuration, isolating one or two compartments allowed testing at A/C ratios of 6.1 

and 6.8 ft/min.

4.3.8 Tube Sheet Pressure Drop

The specified design pressure drop across the TOXECONTM baghouse tube sheet was 

expected to be between 4” w.c. and 6” w.c., which is typical for baghouses installed on coalfired boilers. At this site, the particulate cake consisted of PAC/ash, and adsorption on the 

cake was the primary mercury removal mechanism.

The PIPP baghouse was sized based on WAPC historic design parameters and the design 

guideline of the We Energies specifications. The plenums were sized based on traditional 

flow velocities and were within the guidelines set by the We Energies specifications. Inlet 

and outlet dampers were sized as large as physically possible for the plenums and 

compartments selected. The compartments were provided with vanes and perforated plates 

to achieve the flow and dust distribution required in the specifications and not specifically to 

reduce pressure loss. Inlet and outlet plenums were modeled with various vane arrangements 

to reduce pressure loss without any significant improvements. The model study mechanical 

pressures losses exceeded the expectations of WAPC. WAPC stated the model study results 

were not representative of past WAPC baghouse designs.
4-9

ADA-ES’s calculation using a residual filter drag coefficient generally accepted in the 

industry is listed below. The formula for predicting pressure loss in a fabric filter is:

ΔP = ΔPR +K2V

2Ct/7000 Predictive equation for fabric filter pressure loss, where:

K2 Specific resistance coefficient of freshly deposited dust

(” w.c.)/(ft/min)/(lb/sq ft)

K2 70 (” w.c.)/(ft/min)/(lb/sq ft)

ΔPR Anticipated residual drag was 0.7” w.c./(ft/min) at design air-to-cloth ratio

ΔPR 5.48 ft/min

V Face velocity or A/C (ft/min)

C Dust loading (grains/acf)

t Filtration time (min)

The residual filter drag coefficient of 0.7 for this calculation was conservative for this 

application. The calculated pressure loss based on the above factors was 8.0” w.c. with a 

cleaning time of about 100 minutes. The allotted pressure drop for the PIPP collector was

8.0” w.c. A minimum accepted cleaning cycle time was every 40 minutes.

4.3.9 Model Study Objectives and Results

NELS Consulting Services modeled the baghouse and surrounding ductwork at a 1:12 scale. 

The objectives of the flow model study were to determine the configuration of flow 

distribution devices and to achieve the following:

Determine baghouse gas flow and dust distribution

Confirm design velocities and flow distribution in compartments

Evaluate temperature mixing at the baghouse inlet

Determine pressure drop of system

Confirm minimal dust deposits in the ductwork

Configure PAC injection location flow distribution

Determine velocity distribution and gas flow angle at proposed CEM duct location

Confirm balanced flow in the three stacks
4-10

Flow modeling was used primarily to study gas flow distribution in the inlet and outlet ducts 

and in the baghouse primarily in the hopper region. These model studies can visually show 

gas distribution patterns. Model testing of filter bag and tube sheet loss was not accurate and 

was just used to simulate resistance in the system for the purpose of flow and dust 

distribution. The purpose of the baghouse model study was primarily for flow and dust 

distribution.

The findings indicated that the design goals had been achieved. Additionally, the locations 

and configurations of the flow control vanes were determined by NELS during the testing.

Design velocities within each TOXECONTM baghouse compartment were chosen based upon 

ash-only baghouse designs with similar pressure drop and outlet emissions. Low vertical gas 

velocity at the bottom of the filter bags was desired since this enabled online bag cleaning. 

Providing low vertical gas velocity was accomplished by including gas distribution baffles in 

the compartment inlet hopper area that direct a portion of the gas flow away from the bottom 

of the compartment toward the top of the filter bags. This distribution also had an additional 

benefit of providing a flow pattern that caused the particulate flow to impact the bags rather 

than dropping out when it entered the bag compartment. Deposition of particles on the bags 

was beneficial in this application because it provided gas-solid contact that enabled mercury 

capture, as compared with conventional baghouse applications where particle dropout is 

desirable. The distribution baffles were included in the baghouse model study that confirmed 

their performance.

With regard to particle re-entrainment, the individual particles collected on filter bags 

agglomerate in conventional baghouse applications where fly ash is filtered. This system 

was designed assuming carbon particles would agglomerate with fly ash particles making 

them large and heavy enough to fall to the hopper, not subject to excessive re-entrainment. 

WAPC experience was that a portion of the filter ash cake would fall into the hopper after 

bags were pulsed and a portion of the ash would return to the filter bags. The pulse would 

cause all of the ash cake to break and when a portion of the ash would re-deposit on the filter 

bag the structure of the ash cake would be altered in a manner that further reduces resistance 

to gas flow.
4-11

4.3.9.1 Baghouse Modifications Required After Construction

Several modifications were incorporated to gain more optimal temperature control in the 

baghouse and booster fan building including:

Added larger ventilation fans and louvered windows at the top of the baghouse

Added walls to the upper and lower baghouse areas that block flow of hot air from the 

fan building

Added louvered windows at the booster fan inlet gate level and modified temperature 

controls to achieve better heat control

Added walls and larger heaters to the lower baghouse area

Additional modifications were added to improve structural integrity and maintenance access:

The baghouse covers were rebuilt with checker plate and angle iron. Additional 

stiffeners were added across the width of the covers to improve strength.

A redesigned lifting spreader for the covers was provided to keep from bending the 

covers when trying to open under negative pressure.

Platforms were added to access the booster fan outlet (ref: JPG_006, Appendix D).

Ice breaks were added to the top of the baghouse vent louvers.

4.4 Powdered Activated Carbon System Design

Norit Americas and ADA-ES provided the PAC injection system for Presque Isle. Norit 

Americas supplied the PAC and hardware, while ADA-ES supplied the engineering design 

for the system, and the distribution and duct injection system. The system consisted of two 

general components: the PAC storage and feeding system and the duct injection system. 

The PAC storage and feeding system consisted of a bulk storage silo with pneumatic truck 

unloading capability, three PAC feeder trains each consisting of a feed hopper and variable 
4-12

speed feeder, an eductor, and a transport air blower. This system was complete with the 

necessary control provisions to operate and monitor the system equipment.

The duct injection system consisted of the transport piping from the feeding system and the 

necessary injection lances.

The PAC system was designed for an injection concentration of 3 lbs/MMacf. This projected 

injection rate was based on data obtained from full- and bench-scale testing. Appendix B 

contains a simplified drawing for the PAC system installed at Presque Isle.

The design parameters for the TOXECONTM system using PAC alone at Presque Isle for 

Units 7, 8, and 9 were as follows:

Design flue gas flow rate: 1,200,000 acfm at 350 oF.

PAC design injection concentration: 3.0 lb/MMacf

PAC design injection rate (total): 216 lb/hr

Number of PAC injection trains: 3

Capacity of each train: 200 lb/hr

Total injection capacity: 600 lb/hr

Silo storage capacity: 4,490 cu ft

Silo storage capacity at 35 lb/cu ft: 157,000 lbs or 78 tons

Storage capacity of bulk storage silo at design injection rate: 30 days

Method for determining PAC distribution to the baghouse compartments: physical 

flow modeling, 1:12 scale

As a part of the effort to optimize the design of the injection system and the performance of 

the PAC system for mercury removal, NELS performed physical modeling of PAC injection 

at two locations in the ductwork leading to the baghouse using the existing 1:12 scale model. 
4-13

This modeling looked at the distribution of the injected PAC in the baghouse inlet duct and 

inlet plenum and at the discharge of each of the compartments. The testing used two 

methods for making this determination: visible plume testing in the ducts, and carbon 

monoxide concentration distribution.

The first injection location consisted of a multi-lanced injection grid in the duct just prior to 

the inlet connection to the baghouse. Because of a widely varying flue gas flow distribution 

at this point, the modeling indicated a very uneven PAC distribution to the baghouse 

compartments using this design.

The second injection location consisted of a single injection lance in the round duct at the ID 

fan outlet for each generating unit. The modeling indicated that injecting at these locations 

gave a significantly better PAC distribution to the baghouse compartments.

Based on these tests, the PAC injection system used a single lance in the discharge duct of 

each ID fan. With three feeder trains, each generating unit had a dedicated injection train, 

transport line, and injection nozzle. The injection rate was controlled based on several 

variables, including boiler load/flue gas flow and mercury removal. Two CEMs were used, 

one measuring mercury concentration prior to ACI and the other in the common booster fan 

discharge duct.

The overall system design included the capability to inject a recycled PAC/ash mix collected 

from the baghouse hoppers. Since this mix would include partially spent PAC along with 

ash, the volume of injected material would increase substantially. Thus, the system capacity 

would accommodate the injection of the PAC/ash mix with the design PAC injection rate of 

sorbent (3.0 lb/MMacf) and the ash escaping the HESP. At the time of the original design, 

the benefit of recycling the PAC/ash mixture was unknown. During the demonstration 

program, it was determined that the PAC quickly reached equilibrium with the mercury in 

the flue gas and therefore was unable to sequester more mercury. Sorbent re-injection was 

not tested because of this observation.
4-14

4.5 Balance-of-Plant Considerations

4.5.1 Booster Fans

4.5.1.1 Two versus Three Fans

With the additional pressure drop associated with the installation of the TOXECON

baghouse and associated ductwork, new ID booster fans were required. A study was 

prepared outlining the pros and cons of two versus three booster fans. The final decision to 

select three booster fans was influenced by the following issues:

Three fans would allow designating a single fan for each of the three boiler units, 

thereby maintaining the established practice at the plant of individual components for 

the three units.

The three-fan arrangement had a smaller impact on the plant’s electrical systems.

Turndown of the three-fan arrangement would be greater and would ensure 

compliance with National Fire Protection Association boiler purge flow requirements.

4.5.1.2 Margin (Test Block Performance)

The booster fans were sized for a single unit’s full load flue gas flow and the calculated 

pressure drop of the new ductwork and baghouse. A margin was then applied to these values 

based on typical power industry practice of 15% margin on flow, 32% margin on head, and 

25 oF margin on temperature. The conditions of the fan with margin were referred to as 

“Test Block” conditions. The expected operating conditions were referred to as “Net” 

conditions. Test Block conditions were specified to account for system losses in the actual 

fan installation as compared to the ideal test setup installation with which the fans have been 

shop-tested to determine their capacity.

4.5.1.3 Purge Flow

The booster fans needed to have sufficient turndown capability in order to purge the boiler 

during a unit startup. The initial purge flow requirements were calculated and it was 
4-15

determined that the fan manufacturer needed to install sealing strips on the fan control 

damper to limit leakage. This would achieve the turndown on the fan performance necessary 

to meet the purge flow requirements.

4.5.1.4 Inlet Damper versus Variable Inlet Vanes

A variable inlet vane (VIV) control damper was selected for the booster fans. The VIV has a 

higher efficiency than inlet dampers. A 13–15% increase in power consumption was 

projected when an inlet damper configuration was evaluated. The VIV had a higher initial 

cost; however, the savings in electricity offset this cost.

4.5.1.5 Fan Description

Manufacturer: Fläkt Woods

Quantity: 3

Test Block Rating: 460,000 acfm @ 375 oF with 18.5” w.c.

Net Rating: 400,000 acfm @ 350 oF with 14” w.c.

Total Efficiency: 87.7% (test block), 87.6% (net)

Operating Speed: 893 rpm

Fan Configuration: Double inlet

Fan Blade Style: Airfoil

Fan Bearings: RENK-ERZLQ 18–180mm - Pressure lubricated

Control Damper: Radial Variable-Inlet-Vane (VIV)

Damper Actuator: Jordan Controls SM-60000

Motor Size: 1,700 hp

Motor Voltage: 2,300 Volts

Vibration Transmitters: Alaron Model VT-100

Lube Oil Console Manf.: Howard Martin

Lube Oil Console Capacity: 3.5 gal/min

This minimum design of 400,000 acfm @14” w.c. was consistent with the flow modeling. 

The flow model report stated “the pressure drop measured in the model study ductwork and 

baghouse from the ID fan discharges to the stack was 10.72” w.c., excluding the filter bags, 

ash cake on the bags, and buoyancy effects of the hot flue gas in the stack.” The result of 

summing the expected pressure drop across the bags and cake (4–8” w.c.) and the buoyancy 
4-16

effect of the hot flue gas (negative 1.5–2” w.c.) was 12–16” w.c. This result indicated that 

the design was close to the modeling results.

Each fan was sized for one unit’s flue gas flow. The booster fans controlled the draft on the 

discharge side of the ID fans by modulating VIV control dampers at the fan inlet. The 

booster fans were sized to offset the additional pressure drop of the baghouse and ductwork. 

The booster fan control scheme was to mimic the existing pressure conditions at the ID fans 

discharge prior to the TOXECONTM retrofit by measuring the pressure at the common flue 

gas ductwork and modulating the booster fan dampers. Each booster fan had an isolating 

guillotine gate on the inlet and outlet to allow online maintenance.

4.5.2 Compressed Air System

4.5.2.1 Compressed Air Users

The compressed air system provided instrument quality compressed air to the following 

systems and equipment:

PAC System (10 SCFM)

Ash Handling System (52 SCFM)

Fabric Filter Baghouse (350 SCFM)

Mercury CEMs Shelter (20 SCFM)

4.5.2.2 Capacity and Design

The compressed air system consisted of the compressed air skid and the associated 

distribution piping network. Refer to Drawing 4937-CIA-M0113, Appendix C for a P&ID of 

the compressed air skid. The compressed air skid was supplied by Sullair and included:

Pressure: 80–120 psig (normal operation at 100 psig)

Dew point: -40 oF at 100 psig

Particulate: Less than 1 micron
4-17

Oil Content: 0.008 ppm

Maximum Flow: 475 SCFM

4.5.2.3 Equipment Description

The compressed air system consisted of the compressed air skid and the associated 

distribution piping network. The piping distribution network consisted of ASTM A53 carbon 

steel piping. The compressed air skid included:

Two single stage, heavy duty, flood lubricated rotary screw type compressor units

Coalescing pre-filters

Two fully automatic, regenerative desiccant dryers composed of a fully automatic 

pressure swing, twin tower using an activated alumina desiccant bed

Particle after-filters

Storage tank

Flow controller

4.5.3 Ash Handling System

4.5.3.1 System Type

The ash handling system selected was a dilute-phase pneumatic conveying system. This type 

of system has been used in conveying both fly ash and PAC. The supplier of the system was 

United Conveyor Corporation (UCC).

4.5.3.2 Capacity and Margin

The particulate generation rate was based on the collection rate of fly ash (200 lb/hr max) and 

the maximum injection rate of sorbent (450 lb/hr max). The total maximum baghouse 

loading for fly ash/PAC was 650 lb/hr (0.325 tons/hr).
4-18

The conveying rate of the ash handling system was based on four times the total particulate 

loading rate of 0.325 tons/hr. This converts to 1.3 tons/hr.

4.5.3.3 Ash System Hardware

Refer to drawings M-54025-020 and M-54025-021, Appendix C for piping and 

instrumentation drawings of the ash handling system.

The ash system at Presque Isle was a vacuum dilute-phase transport system. The hardware 

consisted of the ten hoppers in the baghouse, transport lines from the bottom of each hopper 

leading to a filter/separator located on the penthouse of the ash storage silo, the ash storage 

silo itself, and finally trucks to transport the ash for disposal. A mechanical exhauster 

downstream of the filter/separator created the vacuum in the lines.

Each of the ten hoppers had a valve at the bottom to separate the ash from the lines. The ash 

was removed from the hoppers sequentially, starting at the furthest hopper on one side of the 

baghouse. When one side was emptied, the sequence was repeated on the other side. A 

purge cycle then cleared the main line of any residual ash. As each hopper emptied, the 

ash/air mixture was conveyed to the filter/separator. When the level probe in the 

filter/separator was activated, the transport of ash from the hoppers was discontinued. Then 

the exhauster relief and the system relief valves opened to relieve conveyor line vacuum and 

enabled the mechanical exhauster to pull in atmospheric air. After a predetermined time 

delay, the bottom gate opened so the ash discharged by gravity into the storage silo. After 

another predetermined time delay, the bottom gate closed. The exhauster relief and the 

system relief valves then closed, allowing the system to reestablish a vacuum. With 

sufficient vacuum available, ash transporting resumed to the filter/separator.

Fly ash/PAC was removed from the conical bottom storage silo by two different means. The 

fly ash/PAC was conditioned with water and unloaded through a pin paddle mixer, or it could 

be unloaded dry through a telescopic spout.
4-19

4.5.3.4 Unloading System Selection

Disposal of the fly ash/PAC mixture was by open bed trucks to a landfill. A wet unloading 

system was selected to condition the ash/PAC mixture, leaving the storage silo with water 

thereby binding the dust to allow transportation by open bed trucks. A dry unloading system 

was also installed on the ash silo to allow the ash/PAC mixture to be recovered dry for use in 

testing re-injection (recycling) of the mixture into the flue gas stream, or for testing methods 

of recovering the mercury from the used PAC.

4.5.3.5 Modifications to the Ash Handling System since Start Up

Excessive dusting was occurring during the use of the wet unloading system, especially when 

starting the pin mixer. Several possible causes of the dusting were identified:

Inadequate water mixing in the pin mixer

Vacuum relief piping was venting to atmosphere

Inconsistent flow of material from the silo through the valves at the bottom of hopper

Bags in filter/separator improperly installed

Ash becoming airborne at mixer discharge into truck

Wind tunneling effects creating turbulence in uncovered truck beds

Several modifications were incorporated in to the pin mixer: 

The mixer cover was raised to allow the water spray to enter above the rotor (ref: 

JPG_001, Appendix D).

A high-pressure water spray was added and sequenced into the control logic for mixer 

start-up.

Baffles were added in the space above the pin mixer shaft to help control dust flow.

A smaller sprocket was added to the mixer drive to increase the mixer speed.

A VFD was added to allow adjustment of mixer speed.
4-20

Finally, a larger pin mixer was installed (ref: Dwg 5-5200-PIPP, Appendix D). This helped 

to eliminate the dusting and equipment issues seen during the demonstration. The main 

differences between the original mixer and the new mixer were as follows:

Additional fogging nozzles.

The motor was increased from 7.5 Hp to 10 Hp. Mixer speed at 60Hz motor 

frequency was increased from 76 rpm to 100 rpm.

The tensioner design was changed.

Additional modifications were made to improve flow of the PAC/ash mixture:

A new rotary valve was added to replace the original butterfly valve (ref: JPG_007, 

Appendix D).

Although fluidization at the silo discharge was normally not required, the original 

fluidization valves were replaced by three (3) large air cannons (ref: JPG_008, 

Appendix D).

Other modifications to improve operability of the ash unloading system:

A rubber skirt was added to the wet unloading spout to improve dust control (ref: 

JPG_0012, Appendix D).

The sequencing of the exhauster and system relief valves was optimized to allow dust 

to be purged from vacuum relief piping before purging. The 7-9 baghouse fly ash 

system setpoints were modified to provide a better differential pressure between the 

empty line and empty hopper vacuums. Increasing vacuum on hoppers helped to

ensure they emptied.

The plant extended the unloading shelter to the east of the present shelter below the 

silo. This reduced the wind tunneling effect and protected the area from the elements.
4-21

Two recommendations for any similar program were made:

Use a larger pin mixer

Design the silo hopper leg to have a smoother transition into the discharge valves. The 

current design had a somewhat square transition which may have impeded smooth 

flow of PAC/Ash.

New setpoints:

Full load vacuum (hopper valve closes): 6.8" Hg 

Vibrator vacuum (vibrator is activated in this range): 4.7"–2.5" Hg 

Plugged hopper vacuum (if vacuum stays in this range for a fixed amount of time): 

4.7"–2.5" Hg 

Empty line (index – no hopper valves open, pulling air through the intake end check ): 

2.8" Hg 

No load (hopper gate opens - value set between empty line and empty hopper): 2.5" 

Hg 

Empty hopper (pulling on an empty hopper - hopper step sequence after time 

duration): 2.1" Hg

The vacuum relief piping was rerouted from atmospheric release to release back into 

silo.

The vacuum relief piping was insulated (ref: JPG_005, Appendix D).

An external control station was provided to give the operator a better view of 

unloading and minimize exposure to dusting (ref: JPG_003, Appendix D).

A silo inspection hatch, access platform, and inspection port were added at the bottom 

of the straight section to assist inspection of silo internals (ref: JPG_004, 

Appendix D).
4-22

4.5.4 Ductwork

4.5.4.1 Layout, Area Constraints, Existing Ductwork Tie In

The layout of the ductwork system to tie the existing units to the new baghouse was governed 

by the configuration of the existing power plant and its surrounding structures and 

equipment. Refer to general arrangement drawings 4937-CGA-M1000, 4937-CGA-M1001, 

and 4937-CGA-M1002, Appendix C for a layout of the plant. A location north of the 

existing Unit 9 boiler building was the site for the new baghouse. The location of the new 

baghouse was constrained to the north by the existing plant access road and property line, to 

the south by the existing Unit 9 boiler building, to the west by an emergency coal discharge 

chute and administration building, and to the east by the plant access road.

The ductwork layout to tie Units 7–9 to the new baghouse was constrained by the back wall 

of the existing boiler building and the exhaust stack for Units 7–9. With the proximity of the 

new ductwork run to the existing plant, the existing boiler room structure was used to tie into 

the new ductwork support structure. Because of the space constraints between the plant west 

wall and the existing stack, the use of round ductwork was precluded and rectangular crosssection ductwork was utilized. The ID fans for the existing units were located inside the 

existing boiler building near the back wall of the plant. The discharge ducts of the ID fans 

penetrated the back wall of the building and were routed to the exhaust stack location, which 

was centrally located on the centerline of Unit 8. The distance between the back wall of the 

boiler building and the exhaust stack provided just enough room to tie a supply duct and 

return duct into the existing flue gas stream. The supply duct and return duct were routed 

parallel with each other along the back wall of the boiler building and the tie-in location for 

each unit was “stepped” into the ductwork flow stream by increasing the vertical height of 

the common duct as each unit ties in.

4.5.4.2 Velocity Design

The new ductwork was sized to provide a similar cross sectional area to the existing round 

duct, thereby matching the existing velocity. The combined unit ductwork size was larger to 

provide a lower pressure drop. Table 4-4 reflects the sizing of the ductwork and the design 

velocities.
4-23

Table 4-4. Ductwork Sizing Summary.

Duct Section Size

(ft x ft)

Flow Area

(sq ft)

Flow

(acfm)

Velocity

(ft/s)

One unit’s flow – existing duct 9.5 dia 70.88 400,000 94.1

One unit’s flow – new duct 8.5 x 8.5 72.25 400,000 92.3

Two units’ flow – new duct 8.5 x 20 170 800,000 78.4

Three units’ flow – new duct 8.5 x 30 255 1,200,000 78.4

A two-stage static mixer was included in the inlet duct to the baghouse to provide a more 

uniform temperature profile from the three units and promote even carbon distribution across 

the duct cross section. The static mixer consisted of opposed inclined plates and was 

supplied by KOMAX Systems.

4.5.4.3 Structural Design

The structural design aspects of the ductwork system and its supporting structure utilized 

industry standard practices for ductwork and structural steel design. The provisions of the 

American Institute of Steel Construction’s (AISC) Specification for Structural Steel 

Buildings – Allowable Stress Design and Plastic Design (ASD) presented in the AISC 

Manual of Steel Construction – Allowable Stress Design (AISC-ASD) were used with 

allowances made for elevated temperatures in the ductwork system. The load criteria 

governing the design of the structural systems included dead loads; live loads; environmental 

loads such as wind, seismic, and snow loads; and operating loads such as normal and 

transient pressures, unbalanced pressures, operating and excursion temperatures, and ash 

loading. The various load combinations were analyzed to determine the most critical case for 

each component of the system. Once the most critical load case was determined for a 

particular component, the structural aspects of that component were designed to withstand 

the loads being applied. This philosophy was carried through the entire structural system to 

determine member sizes, spacing, and ductwork support locations.
4-24

4.5.4.4 Diverter Damper Provisions

The ductwork from each unit between the ID fan and the stack was modified to install two 

diverter dampers in series forming a four-port arrangement. The first port was connected to 

each unit’s ID fan discharge ductwork, the second port was connected to ductwork that 

combined the flue gas flows from all three units into a common header directed to the fabric 

filter baghouse, the third port connected to the common return ductwork from the baghouse, 

and the fourth port connected to each unit’s stack. When flue gas was directed to the 

baghouse, the diverter dampers were aligned to block the direct flow of flue gas to the stack. 

If required, the diverter dampers could close the supply and return ductwork to the baghouse 

and bypass the flue gas directly to the stack. Normally, the combined flows of all three units 

were directed by the common ductwork to the fabric filter baghouse. Since this was a test 

project for the TOXECONTM system, the ability to align the flue gas to the baghouse or the 

stack was a design criterion. The need for diverter dampers in a commercial application 

would most likely not be required.

An engineering and economic evaluation prior to damper procurement compared the costs 

associated with installation of three diverter dampers in lieu of nine guillotine type dampers. 

Based on considerations including the purchase cost of the dampers, the required ductwork 

costs, and flue gas pressure drop through the dampers and associated ductwork, the total 

evaluated life cycle costs of utilizing the diverter dampers for this application provided an 

overall savings in cost when compared to the guillotine damper option.

4.5.4.5 Diverter Damper Upgrades since Start Up

Baghouse discharge duct pressures varied from slightly positive at Unit 9 to negative at 

Units 7 and 8. The positive pressure at the Unit 9 diverter damper allowed exhaust gas to 

leak back through the seal air system and corrode seal air fan blades. A new tighter sealing, 

10” Ultraflo Cast Iron actuated valve was installed and seal air logic was modified to ensure 

that seal air valves were shut during fan cycling to minimize possibility of leakage.
4-25

4.5.4.6 Ductwork Modifications since Start Up

Two inches of insulation was added to the exterior of all expansion joints on the baghouse 

ductwork (approximately 28 places) to minimize corrosion due to flue gas condensation on 

cold spots in and around the joints.

4.5.4.7 Access Platform Additions since Start Up

Four (4) access platforms were added to the baghouse discharge ducts. Three (3) platforms 

(one for each unit) were located underneath the ductwork at the 90 elbows just upstream of 

the diverter damper. These platforms allow access to hatch covers that provide maintenance 

access to the dampers. The fourth additional platform was added on top of the Unit 8 

ductwork to provide access to the baghouse. Pictures of these platforms are included in 

Appendix D (ref: JPG_009 & JPG_010, Appendix D).

4.5.5 Electrical

4.5.5.1 Electrical Constraints and Upgrades

Presque Isle Power Plant is a mature power plant that has been expanded and developed over 

the course of many years. When installed, the plant electrical systems were designed for 

nominal load growth. Emissions controls and other upgrades have stretched some of the 

plant electrical systems past their design parameters.

For startup, the plant relies on reserve system transformers to provide power to the individual 

unit switchgear, until the time that the unit is up to operating speed and capable of powering 

the unit electrical loads via the unit auxiliary transformer. During a unit trip, the unit 

electrical requirements are transferred from the unit auxiliary transformer to the reserve 

system to maintain boiler draft and safely shut down unit loads.

Units 7, 8, and 9 switchgear (2,400 VAC) were studied to determine if the existing gear 

could adequately power the running load, and were capable of starting the motors. The plant 

reserve system was also checked to see if it could provide enough power to satisfy the 

requirements of startup and multiple unit trips. The study verified the suitability of the 
4-26

switchgear to handle the new running loads, but pointed out deficiencies in the reserve 

system used during emergency situations.

As a result of the study, upgrades to the plant reserve electrical system were identified and 

implemented to ensure the success of the TOXECONTM project. Refer to drawings 4937-

CMP-E1000 and 4937-CMP-E1001, Appendix C for an overview of the one-line diagram.

4.5.5.2 Electrical System Configuration and Hardware

The electrical systems supporting the baghouse were related to the function and size of the 

baghouse equipment. To achieve the desired exhaust gas flow from boiler to stack, ID 

booster fans were added to the baghouse outlet to compensate for the pressure drop across 

the baghouse and ductwork to maintain suitable flow to the stack. These booster fan motors 

were each rated 1,700 hp, with one booster fan associated with each unit. These motors were 

controlled by dedicated medium voltage starters, which are fed from the unit 2,400-volt 

switchgear attached individually from each respective unit. The motor starters receive 

commands from the baghouse distributed control system (DCS) for start/stop, and supply 

information to the DCS to allow operators in the control room to monitor booster fan 

performance. Based on the limitations of the existing plant electrical system and the reserve 

bus design, the motors were designed for a soft start utilizing an autotransformer. This 

allowed the individual motors to start at reduced voltage and current draw.

Remaining baghouse systems comprised the balance-of-plant electrical system. These loads 

were powered from motor control centers (MCCs) operating at 480 volts. This system 

provided the operating power for all core baghouse functions, as well as the PAC injection 

system, ash handling, booster fan lube oil system, air compressors, the DCS system, lighting, 

HVAC, and damper operation for flue gas control.

Essential 480-volt loads were fed from MCCs, which received power from existing plant 

equipment to ensure the most reliable source and functionality possible.
4-27

4.5.6 Instrumentation and Controls

The existing plant DCS system was based on the Emerson Ovation®platform. The DCS 

system expansion required to support the Presque Isle Power Plant TOXECONTM project was 

based on this same platform.

An overview of the DCS expansion for the PIPP TOXECONTM project is shown on the 

Control System Overview drawings 4937-CCX-K6000 and 4937-CCX-K6001, Appendix C. 

This expansion provided all functions required for controlling the plant equipment and 

monitoring of other plant systems installed as part of the TOXECONTM project.

The DCS expansion included three new cabinet groups that were interconnected as shown on 

the Control System Overview drawings. Each cabinet group consisted of the required 

redundant controllers, I/O modules, redundant power supplies, communication modules, and 

other components as required to implement the required control strategies.

One of the cabinet groups (Unit 8, Drop 4) provided control and monitoring for the 

baghouse. Unit 8, Drop 4 consisted of the following cabinets:

79CX-CPU-0004 (Processor I/O Cabinet)

79CX-EXP-0004A (Expansion I/O Cabinet)

A second cabinet group consisting of unitized remote I/O cabinets (Unit 7, Drop 1; Unit 8, 

Drop 1; Unit 9, Drop 1) was dedicated to providing controls interfaces with the existing plant 

control system for booster fan draft control, control of their respective unit booster fans, 

control of their respective unit baghouse supply and return diverter dampers, and control of 

their respective baghouse supply and return diverter damper seal air blowers and valves. The 

remote I/O (RIO) group consisted of the following cabinets:

7CX-RIO-0001 (Unit 7 RIO)

8CX-RIO-0001 (Unit 8 RIO)

9CX-RIO-0001 (Unit 9 RIO)
4-28

The third cabinet group (Unit 8, Drop 5) was dedicated to control of the remaining 

TOXECONTM balance-of-plant (BOP) equipment including booster fan draft control, fly ash 

system, PAC injection system, compressed air system, and baghouse outlet mercury CEMs. 

Unit 8, Drop 5 consisted of the following cabinets:

79CX-CPU-0005 (Processor I/O Cabinet)

79CX-EXP-0005A (Expansion I/O Cabinet)

79CX-EXP-0005B (Expansion I/O Cabinet)

79CX-EXP-0005C (Expansion I/O Cabinet)

4.6 Mercury Measurements

When this CCPI program was selected in 2003, stack compliance-grade continuous 

emissions monitor (CEM) mercury monitors were not available. Several research-grade 

mercury monitors were proven to be accurate and reliable; however, they required operation 

by a highly skilled engineer and continuous maintenance.

Throughout the demonstration project, ADA-ES worked with Thermo Electron (now Thermo 

Fisher) Corporation to develop a mercury CEM for use on this program to measure mercury 

concentrations at the inlet and outlet of the TOXECON fabric filter. ADA-ES’s role was 

to validate different components by operating them in parallel with ADA-ES’s semicontinuous mercury monitor. The Thermo instrument had four key components: sample 

extraction probe, sample converter, mercury analyzer, and calibration module. Figure 4-1

shows a schematic of these components.
4-29

Figure 4-1. Schematic of Thermo Prototype Mercury CEM.

The extraction probe used an inertial filter to obtain a particulate-free vapor-phase sample 

without passing the gas through a fly ash filter cake. This minimized the sample gas 

interactions with the fly ash, which could cause sampling artifacts. An eductor, driven with 

compressed, dry, mercury-free motive air, drew the ash-free sample from the inertial filter. 

The line between the inertial filter and the vacuum port on the eductor contained a criticalflow orifice. To maintain a constant sample flow rate to the analyzer, the eductor diluted the 

sample with the motive air resulting in a dilution ratio between 25:1 and 100:1, depending on 

the size of the critical-flow orifice. The dilution ratio was determined based on flue gas 

conditions and operator preference. All of the extraction probe internal surfaces exposed to 

sample gas had a glass coating to prevent unwanted chemical reactions with the mercury.

Calibration gas from the calibration module was introduced into the sample stream either 

upstream or downstream of the inertial filter.

The converter module converted the oxidized mercury in the diluted sample to elemental 

mercury for a total vapor-phase mercury measurement, or it scrubbed oxidized mercury from 

Mercury Analyzer

Mercury Calibrator

Chamber

Hg Source

Hg Scrubber

Clean, Dry Air

Eductor

Dilution Air

Air

Probe Control Module

(Pressure and Temperature)

Zero Air Supply Hg Scrubber

Hg Total

Hg Elem

Blowback Air

Zero Air

Hg Span

Probe/Converter

Orifice Inlet

Filter Inlet

Converter

Scrubber

Diluted sample

Exhaust

c

c

c

c

c

c

c
4-30

the diluted sample to deliver only elemental mercury to the analyzer when a speciated 

measurement is desired. The proprietary design combined high temperature (> 750 oF) and a 

chemical reaction to achieve the conversions.

The analyzer measured mercury directly using Cold Vapor Atomic Fluorescence technology. 

Because the sample was diluted, it had low moisture, was relatively non-reactive, and 

therefore had minimal interference from other gases. The analyzer detection limit was 

1 ng/m3( 0.1 ppt) and no cross interference from SO2 has been observed.
5-1

5.0 PROCESS CAPITAL COST

The capital cost associated with construction of the TOXECONTM was $34,644,237. This is 

the actual installed cost expressed in 2005 dollars. A listing of the costs by major equipment 

item is shown in Table 5-1.

Table 5-1. Summary of Equipment, Balance-of-Plant, and Engineering Costs.

TOXECONTM and Balance-of-Plant Equipment and Installation Costs

Presque Isle Power Plant Units 7, 8, and 9

Item Description Cost

Baghouse

Baghouse Supply and Erection $9,728,779

Equipment

Electrical Equipment $624,102

Controls (Including Enclosure) $295,295

Air Compressor/Dryer $121,589

ID Booster Fans $1,199,802

Ash System $623,789

PAC System $360,786

Dampers $655,744

Expansion Joints $101,519

Ductwork and Structural Steel $3,114,209

Erection

Construction Supervision and Indirects $1,659,883

Foundations $1,603,112

Electrical Installation $1,455,979

Mechanical and Structural Installation $7,796,968

Other

Engineering Costs (A/E and Utility) $3,949,052

Mercury Continuous Emissions Monitors (2) $1,353,629

TOTAL (excludes testing program costs) $34,644,237
5-2

Baghouse: Includes baghouse casing structure and support steel, hoppers, bags and cages, 

maintenance elevator, exterior siding and roof structure, inlet and outlet plenums, access 

stairways and platforms.

Electrical Equipment: Includes medium voltage motor starters, motor control centers, and 

transformers.

Controls: Includes a digital control system and a prefabricated enclosure for the digital 

control system equipment.

Air Compressor/Dryer: Includes skid mounted air compressor with an air receiver tank and 

dryer.

ID Booster Fans: Includes booster fans, motors, lube oil skid, and fan control instruments.

Ash System: Includes ash storage silo, ash piping and ash hopper valves, vacuum 

exhausters, and ash system controls.

PAC System: Includes powdered activated carbon storage silo, blower, piping, injection 

ports, and control instruments.

Dampers: Includes damper assemblies and drives.

Expansion Joints: Includes ductwork expansion joint material and hardware.

Ductwork and Structural Steel: Includes, ductwork to and from the baghouse, internal 

turning vanes, static mixer, ductwork support steel, booster fan building support steel, access 

platforms, and stairways.

The bulk of the construction consisted of site fabrication of process elements. One notable 

exception was the PAC system which was pre-fabricated. Construction commenced in 

November, 2004 and ended in December 2005. This resulted in significant work being done 

during winter weather conditions which can be severe at this location. Construction costs in 

a milder climate would be expected to be somewhat less.
5-3

This installation was a retrofit application which represents higher costs than would be 

required for a new plant application. However, it is felt that new plant applications of the 

TOXECONTM technology as demonstrated at this site are unlikely. This is because hot-side 

ESP installations on units burning PRB coal are no longer being considered. The application 

of retrofits using TOXECONTM technology is expected to continue.

5.1 Additional Cost of Modifications since Start Up

Table 5-2 is a summary of changes made to the TOXECONTM installation which were not 

covered in the original proposed costs shown in Table 5-1. These additional costs are broken 

down into four categories: Baghouse; Pin Mixer; Silo/Unloading; and Diverter Dampers and 

Ductwork. In general, these changes were considered necessary to meet the performance 

specifications set forth in the original contract and to ensure trouble-free operation in the 

future. The cost for the additional modifications was $413,500.
5-4

Table 5-2. Additional Equipment Costs since Startup.

Item: Baghouse Material Labor

Install larger ventilation fans: upper baghouse $15,000 $5,000

Install larger louvered windows: upper BH $3,000 $5,000

Install louvered windows booster fan inlet $4,000 $5,000

New heaters: lower baghouse Warranty $10,000

Insulating wall: lower baghouse $2,500 $2,500

Insulating wall: upper baghouse $2,500 $2,500

Rebuild baghouse covers: checkerplate and angle iron $3,000 $5,000

Build new lifting spreader $1,000 $2,000

Platform additions at booster fan outlet $30,000 $25,000

Ice breaks upper baghouse vent louvers $500 $1,000

Sheet metal cover for purge air piping $500 $500

Item: Pin Mixer

Add high pressure washer $2,500 $500

Add baffles $200 $400

Modify cover (raise) $1,500 $500

Add higher speed drive sprocket $500 $1,000

Item: Silo/Unloading

Add rotary valve $8,000 $1,000

Add (3) air cannons $3,000 $1,500

Add rubber skirt to wet unloading spout $1,500 $500

Add rubber truck skirt to enclosure $1,500 $500

Add external control station $8,000 $2,000

Insulate/modify vacuum relief piping $500 $500

Add silo hatch $1,500 $1,000

Add inspection nozzle for above $200 $200

Add platform for silo hatch $2,500 $2,000

Extend ash unloading building $100,000

Item: Diverter/Dampers/Ductwork

Replace 10” seal air valve 4,500 $500

Insulate expansion joints (~ 28 plcs) 10,000 $65,000

Add (3) platforms under duct for Diverter access 15,000 $15,000

Add (1) platform on top of unit 8 20,000 $15,000

Total Cost 142,900 270, 600
6-1

6.0 ESTIMATED OPERATING COSTS

The operating costs for TOXECONTM were determined based on actual project expenditures 

associated with long term, ongoing operation. This does not include costs associated with 

testing, technology demonstration, or other costs not directly related to standard utility 

practice. These costs are in 2008 dollars and are summarized in Table 6-1. The operation is 

assumed to target an average 90% mercury removal level on a long-term basis.

Table 6-1. Summary of Operating and Maintenance Costs.

TOXECONTM Summary of Operating & Maintenance Costs

Annual Fixed O&M Cost

Cost, $/yr

Operating Labor 27,851

Maintenance Labor 18,574

Maintenance Material 255,719

Administration/Support Labor 43,586

Sub-Total Annual Fixed O&M Cost 345,730

Variable Operating Cost

Commodity Unit $/Unit Qty/hr Cost $/hr

Powdered Activated Carbon lb 1.009 72.8 73

Electric Power kW 0.02 3000 60

Waste Disposal Charges ton 81.5 0.07 11

Sub-Total Annual Variable Cost 145

The startup of the TOXECONTM facility began on December 17, 2005, and was completed 

on February 12, 2006. The costs associated with this activity are shown in Table 6-2 and 

were $360,000 (based on year of occurrence dollars).
6-2

Table 6-2. Summary of Startup Costs.

TOXECONTM Summary of Startup Costs

Description Cost

Internal Labor $50,563

Misc. Expenses $62,332

Contractor Support $148,145

Electrical Power $83,520

PAC $33,004

Waste Disposal $15,405

TOTAL $359,965
7-1

7.0 COMMERCIAL APPLICATIONS

This demonstration project was the first dedicated, full-scale use of the TOXECONTM 

process and identified issues relating to the technology itself and balance-of-plant issues. 

Valuable experience was gained by testing a full-scale TOXECONTM unit over the course of 

several years, allowing fine-tuning of the process. Testing for simultaneous removal of SO2

and NOx, and mercury using trona injection showed that there is a significant negative impact 

on mercury removal when injecting trona at the levels required for SO2 removal. Testing of 

new bag fabrics will also aid others in choosing fabrics for their installation. Marketplace 

acceptance will be higher by demonstrating long-term use of the TOXECONTM process and 

providing economic information so that other potential users can determine if TOXECONTM 

is cost-effective for their situation.
8-1

8.0 REFERENCES AND BIBLIOGRAPHY OF OTHER PROJECT 

REPORTS

Bustard, C.J. (2003). “Field Test Program to Develop Comprehensive Design, Operating, 

and Cost Data for Mercury Control Systems: Final Site Report for Pleasant Prairie Power 

Plant Unit 2, Sorbent Injection into a Cold-Side ESP for Mercury Control.” Topical Report 

No. 41005R12, U.S. DOE Cooperative Agreement No. DE-FC26-00NT41005, May.

Bustard, C.J., C. Lindsey, P. Brignac, T. Starns, S. Sjostrom, T. Taylor, and C. Larson 

(2003). “Field Test Program for Long-Term Operation of a COHPAC System for 

Removing Mercury from Coal-Fired Flue Gas,” Quarterly Technical Report, Report 

#41591R05, October 31.

Bustard, C.J., C. Lindsey, P. Brignac, T. Starns, S. Sjostrom, T. Taylor, and C. Larson 

(2004). “Field Test Program for Long-Term Operation of a COHPAC System for 

Removing Mercury from Coal-Fired Flue Gas,” Quarterly Technical Report, Report 

#41591R09, October 25.

Bustard, C.J. (2004). “Full-Scale Evaluation of Mercury Control by Injecting Activated 

Carbon Upstream of ESPs and Fabric Filters,” presented at the Air & Waste Management 

Association, Rocky Mountain States Section, 2004 Technical Fall Conference, Denver, CO, 

September 30.

Bustard, C.J., M. Durham, C. Lindsey, T. Starns, K. Baldrey, C. Martin, S. Sjostrom, R. Slye, 

S. Renninger and L. Monroe (2001). “Full-Scale Evaluation of Mercury Control with 

Sorbent Injection and COHPAC at Alabama Power E.C. Gaston,” presented at the 

A&WMA Specialty Conference on Mercury Emissions: Fate, Effects, and Control and The 

US EPA/DOE/EPRI Combined Power Plant Air Pollutant Control Symposium: The MEGA 

Symposium, Chicago, IL, August 20–23.

Bustard, C.J., T. Grubb, R. Merritt, S. Sjostrom, R. Chang, A. Casey, K. Turchi, and R. 

Jeanes (2001). “TXU Big Brown COHPAC Performance Improvement with High 

Permeability Fabric,” presented at A&WMA Specialty Conference on Mercury Emissions: 
8-2

Fate, Effects and Control and the US EPA/DOE/EPRI Combined Power Plant Air Pollutant 

Control Symposium: The MEGA Symposium, Chicago, IL, August 20–23.

Durham, M.D. (2003). “Field Test Program to Develop Comprehensive Design, Operating 

and Cost Data for Mercury Control,” presented at the DOE/NETL Mercury Control 

Technology R&D Program Review Meeting, Pittsburgh, PA, August 12.

Greiner, G. P. 1993. “Fabric Filter - Baghouses II. Operation, Maintenance, and Trouble 

Shooting (A User’s Manual).” Salem, VA: Valley Printers.

Government Accountability Office (2005). “Emerging Mercury Control Technologies Have 

Shown Promising Results, but Data on Long-Term Performance Are Limited,” report to 

Congressional Requesters, GAO-05-612, May.

McKenna, J. D. and J. H. Turner. 1989. “Fabric Filter-Baghouses I. Theory, Design, and 

Selection.” Roanoke, VA: ETS.

Miller, R., W. Harrison, B. Corina, K. Cushing, and R. Chang (1999). “COHPAC

(Compact Hybrid Particulate Collector) The Next Generation in Particulate Control 

Technology, Alabama Power Company’s E.C. Gaston Units #2 and #3: A Success Story,” 

presented at the EPRI-DOE-EPA Combined Utility Air Pollution Control Symposium: The

MEGA Symposium, Atlanta, GA, August 16–20.

Sjostrom, S. (2005). “Thermo Relative Accuracy Tests at Presque Isle,” memorandum.

Sjostrom, S., T. Ebner, T. Ley, R. Slye and R. Chang (2002). “Evaluation and Comparison 

of Novel, Low-Cost Sorbents for Mercury Control,” presented at the Nineteenth Annual 

International Pittsburgh Coal Conference, September 23–27.

We Energies (2009). “TOXECONTM Retrofit for Mercury and Multi-Pollutant Control on 

Three 90-MW Coal-Fired Boilers: Project Performance and Economics Report.”

We Energies (2006). “TOXECONTM Retrofit for Mercury and Multi-Pollutant Control on 

Three 90-MW Coal-Fired Boilers: Preliminary Public Design Report.”
Appendix A. PAC Data Sheet

Appendix B. PAC Injection System Flow Diagram
Appendix C. Drawings

This Appendix contains the following drawings related to the project:

Drawing Title

4937-CGA-M1000 Site Plan

4937-CGA-M1001 Flue Gas Ductwork West Elevation

4937-CGA-M1002 Baghouse and Fan Enclosure Elevation

4937-CGA-M1003 Fan Enclosure Plan and Sections

4937-CGA-M1004 Flue Gas Ductwork Sections and Details

4937-CBA-M0112 P&ID Flue Gas System

4937-CIA-M0113 P&ID Compressed Air Skid

M-54025-020 P&ID Fly Ash System

M-54025-021 P&ID Fly Ash System

4937-CMP-E1000 One-Line Diagram

4937-CMP-E1001 One-Line Diagram 7–9

4937-CCX-K6000 Control System Overview

4937-CCX-K6001 Control System Overview





F6

PI07MBAK000013

DCS

841G

PT

INDOOR

OUTDOOR

4"

4"

4"

4"

HG

839A

AE

STATIC

MIXER

826

ZSC

826

ZSO

DCS

826

XO

826

XC

822

XC

822

XO

DCS

822

ZSO

822

ZSC

818

XO

818

XC

818

ZSC

818

ZSO

DCS

816

XO

816

XC

816

ZSC

816

ZSO

DCS

824

XO

824

XC

824

ZSC

824

ZSO

DCS DCS

820

ZSO

820

ZSC

820

XC

820

XO

NOTE 3

PM

HG

840

AE

839C

AE

WHEELABRATOR 10 COMPARTMENT 

FABRIC FILTER BAGHOUSE 

SEE P&ID’s

3905-3-110

3905-3-111 

DCS

BOOSTER 

FAN C

BOOSTER 

FAN B

BOOSTER 

FAN A

BA-79-BH-FN-B BA-79-BH-FN-C BA-79-BH-FN-A

STATIC

MIXER

815F

TE

815A

VE

815G

TE

815B

VE

815

ZT

815

FZ

DCS

DCS

DCS DCS

DCS

819F

TE

819A

VE

819G

TE

819B

VE

819

ZT

819

FZ DCS

DCS

DCS

DCS DCS

DCS DCS

DCS DCS

DCS

DCS

DCS

823

FZ

823

ZT

823B

VE

823G

TE

823A

VE

823F

TE

WAS: ________________

B

C

D

E

F

8 7 6 5 4 3 2

B

C

D

E

F

DRAWN PI 07 

... .....

APVD D

3

CHKD

APPROVED

AS NOTED

DATE SCALE

2

ANN ARBOR, MI 48108

5405 DATA COURT, SUITE 100

CUMMINS & BARNARD, INC.

REF FILES

CONSULTING

ENGINEERS

SINCE 1932

DRAWN

CHECKED

...

MICROFILM NO.

TEL (734) 761-9130 FAX (734) 761-9881

493704

ORDER NO.

JOB NO.

.....

DATE

DATE CGS NO.

REVISION

1

$DATE$

4937-CBA-M0112

SM

2

SHEET

FLUE GAS SYSTEM 

PIPING & INSTRUMENT DIAGRAM

PRESQUE ISLE POWER PLANT

A

ORDER NO.

REFERENCE DRAWINGS A

8 7

REVISION DESCRIPTION

REV

NO. DATE ORDER NO.

6

0

5

JOB DRAWN CHKD APVD DATE

REV

NO.

10/11/04

REVISION DESCRIPTION

4

FOR CONSTRUCTION

JOB

NOTES:

1. KOMAX SYSTEMS DWG 28055

2. SIX(6) - 6" TESTING PORTS

3. SAMPLE PORT FOR TEMPORARY NOx, SO2 MONITORING

4. ALTERNATE PAC INJECTION EIGHT (8) 6" PORTS

5. UNIT NUMBER IS 79 UNLESS NOTED OTHERWISE.

6. SYSTEM CODE IS BA UNLESS NOTED OTHERWISE.

7. PIPING AND INSTRUMENT CONNECTION SIZES ARE AS 

FOLLOWS UNLESS NOTED OTHERWISE

 -PRESSURE CONNECTIONS - 2" NPT

 -TEST CONNECTIONS - 2" NPT

8. SEE DRAWINGS PI07MBAK000012 (4937-CAA-M0100) FOR 

SYMBOL LEGEND.

9. TE 896A-C AND 897A-C INSTALLED BY WHEELABRATOR.

10. WATER INSPECTION PORTS (14)

BA-79-BH-FN-AA-DA-IL BA-79-BH-FN-BB-DA-IL BA-79-BH-FN-CC-DA-IL

BA-79-BH-FN-AA-DA-OE BA-79-BH-FN-BB-DA-OE BA-79-BH-FN-CC-DA-OE

FROM ID FANS

BA-79-BH-EJ-9

BA-79-BH-EJ-10

BA-79-BH-EJ-11

BA-79-BH-EJ-12

BA-79-BH-EJ-13

BA-79-BH-EJ-15

BA-79-BH-EJ-16 BA-79-BH-EJ-17 BA-79-BH-EJ-18

BA-79-BH-EJ-25 BA-79-BH-EJ-26 BA-79-BH-EJ-27

BA-79-BH-EJ-19 BA-79-BH-EJ-20 BA-79-BH-EJ-21 BA-79-BH-EJ-22 BA-79-BH-EJ-23 BA-79-BH-EJ-24

BA-79-BH-EJ-28

BA-79-BH-EJ-29

BA-79-BH-EJ-30

79BA901

79BA902

79BA903

79BA904

79BA905

WAPC

WAPC

ISOLATION DAMPER

ISOLATION DAMPER

ISOLATION DAMPER

ISOLATION DAMPER

ISOLATION DAMPER

ISOLATION DAMPER

NOTE 1

NOTE 1

NOTE 2

C&B #4937.1.1C10198

354533

115894

MBAK 000 014 2

TO STACK

F4

PI07MBAK000013

FAN ISOLATION DAMPER SEAL AIR SYSTEM TAG NUMBERS

 FAN C

BA-79-BH-FN-CC-DA-IL-SL

79BA001C

ZSO-824A

ZSC-824A

XO-824A

XC-824A

BA-79-BH-FN-CC-DA-OE-SL

79BA002C

ZSO-826A

ZSC-826A

XO-826A

XC-826A

 FAN B

BA-79-BH-FN-BB-DA-IL-SL

79BA001B

ZSO-820A

ZSC-820A

XO-820A

XC-820A

BA-79-BH-FN-BB-DA-OE-SL

79BA002B

ZSO-822A

ZSC-822A

XO-822A

XC-822A

 FAN A

BA-79-BH-FN-AA-DA-IL-SL

79BA001A

ZSO-816A

ZSC-816A

XO-816A

XC-816A

BA-79-BH-FN-AA-DA-OE-SL

79BA002A

ZSO-818A

ZSC-818A

XO-818A

XC-818A

ITEM DESCRIPTION

INLET DAMPER

 SEAL AIR BLOWER

 SEAL AIR ISO VALVE

 OPEN LIMIT SWITCH

 CLOSE LIMIT SWITCH

 OPEN COMMAND

 CLOSE COMMAND

OULET DAMPER

 SEAL AIR BLOWER 

 SEAL AIR ISO VALVE

 OPEN LIMIT SWITCH

 CLOSE LIMIT SWITCH

 OPEN COMMAND

 CLOSE COMMAND

DCS

XC

XO

ZSC

ZSO

M

GUILLOTINE 

ISOLATION 

DAMPER

SEAL AIR 

BLOWER

NC 79BA003A NC 79BA003B NC 79BA003C

DRAIN 

TO SLAB

DRAIN 

TO SLAB

DRAIN 

TO SLAB

01A-C15-2" 01B-C15-2" 01C-C15-2"

01A-C15-2" 01B-C15-2" 01C-C15-2"

NOTE 2

6"

NOTE 3

NOTE 3

NOTE 4

6"

6"

4"

4"

1 01/10/05 REVISED PAC INJECTION LOCATION, TAG NUMBERS

JLC JAC JAC

1

NOTE 10

TE

897C

TE

897B

TE

897A

TE

896C

TE

896B

TE

896A

NOTE 9

NOTE 9

2 02/11/05 ADDED INSTRUMENTATION

JLC JAC JAC

TE

815CB

TE

815DB

TE

815EB

TE

815EA

TE

815CA

TE

815DA

TE

815AA

TE

815BA

TE

815AB

TE

815BB

TE

819CB

TE

819DB

TE

819EB

TE

819EA

TE

819CA

TE

819DA

TE

819AA

TE

819BA

TE

819AB

TE

819BB

TE

823CB

TE

823DB

TE

823EB

823CA 823DA 823EA

TE

823AA

TE

823BA

TE

823AB

TE

823BB

TE TE TE

2

2

2

2

2

2

2
8

A

REFERENCE DRAWINGS

F

E

D

C

B

8 7 6 5 4 3 2

0

F

E

D

C

B

A

$DATE$WAS: ________________

JOB

PRESQUE ISLE POWER PLANT

PIPING & INSTRUMENT DIAGRAM

COMPRESSED AIR SKID SYSTEM 

SHEET

0

SM

4937-CIA-M0113

1

REVISION

CGS NO. DATE

DATE

.....

JOB NO.

ORDER NO.

493704

TEL (734) 761-9130 FAX (734) 761-9881

MICROFILM NO.

...

CHECKED

DRAWN

SINCE 1932

ENGINEERS

CONSULTING

REF FILES

CUMMINS & BARNARD, INC.

5405 DATA COURT, SUITE 100

ANN ARBOR, MI 48108

2

DATE SCALE

AS NOTED

APPROVED

CHKD

3

APVD D

... .....

DRAWN PI 07 

4

REVISION DESCRIPTION

REV

NO. JOB DRAWN CHKD APVD DATE ORDER NO.

6 5

DATE ORDER NO.

REV

NO. REVISION DESCRIPTION

7

0001

PT

0001

TE

0001

PI

0001

TI

TRAP

TRAP

TRAP

PORTABLE 

COMPRESSOR 

CONNECTION

WET AIR RECEIVER

COMPRESSOR A

100%

COMPRESSOR B

100%

AIR DRYER

SKID

AIR DRYER

SKID

PARTICULATE

FILTER

COALESCING FILTER

125 PSIG

SET @

0001

PSV

FO

DRAIN 

CONNECTION

DCS

DCS

EXPANSION 

JOINT

EXPANSION 

JOINT

COALESCING FILTER

PARTICULATE

FILTER

NOTES:

1. DIFFERENTIAL PRESSURE INDICATOR IS INTEGRAL TO 

FILTER.

MSAK 000 003

INST. AIR DIST.

DCS

DCS

DCS

DCS

DPI

NOTE 1

DPI

NOTE 1

DPI

NOTE 1

DPI

NOTE 1

SET AT

100 PSI

PI07MBAK000012 "P&ID LEGEND"

VENT

VENT

0 03/04/05 FOR CONSTRUCTION

TRAP

79IA100

79IA101

79IA103

79IA104 79IA105

79IA117 79IA118

79IA119 79IA120

79IA121 79IA122

79IA123

79IA107

79IA106 79IA108

79IA109

79IA111

79IA116

79IA102

79IA115

79IA114 79IA113 79IA112

79IA110

 PV

001

001

 PV

PI07MIAK000002

B8

AI-79-BH-DY-AA

AI-79-BH-DY-BB

AI-79-BH-CM-TK

AI-79-BH-CM-BB

AI-79-BH-CM-AA






Appendix D. Modifications Since Startup

This Appendix contains the following photos and drawing related to the project:

Photo Title

JPG_001 Raised Cover Pin Mixer

Dwg 5-5200-PIPP New Pin Mixer

JPG_002 Baghouse Pulse Pipe Cover

JPG_003 External Control Panel Ash Silo

JPG_004 Silo Access Hatch and Inspection Port

JPG_005 New Insulation Vacuum Unloading Pipes

JPG_006 New Platform – Booster Fan Outlet (TYP 3)

JPG _007 New Rotary Valve for Ash Unloading

JPG_008 Air Canon (TYP3)

JPG_009 Platform on Top of Duct Unit 8

JPG_010 Platform for Diverter Access Doors

JPG_011 Ash Unloading Truck Enclosure

JPG_012 Rubber Skirt, Wet Unloading System
JPG_001: Raised Cover Pin Mixer
...\WinWord\DEL'VE\5-5200-PIPP.d

gn 12/7/2009 1:10:18 PM
JPG_002: Baghouse Pulse Pipe Cover
JPG_003: External Control Panel Ash Silo

 
 JPG_004: Silo Access Hatch and Inspection Port 

 
 JPG_005: New Insulation Vacuum Unloading Pipes

 
JPG_006: New Platform – Booster Fan Outlet (TYP 3)
 JPG _007: New Rotary Valve for Ash Unloading

 
JPG_008: Air Canon (TYP3)
JPG_009: Platform on Top of Duct Unit 8 
JPG_010: Platform for Diverter Access Doors 
JPG_011: Ash Unloading Truck Enclosure
JPG_012: Rubber Skirt, Wet Unloading System