# WET FLUE GAS DESULFURIZATION FGD  SYSTEMS ADVANCED TECHNOLOGY FOR MAXIMUM SO 2 

# REMOVAL

# B & 

# W WET FGD SYSTEMS

– FLEXIBILITY OF DESIGN AND ADVANCED FEATURES TO MEET CUSTOMER NEEDS When performance counts

SINCE 1971, THE BABCOCK & WILCOX COMPANY’S ( B & 

### W ) WET
FLUE GAS DESULFURIZATION ( FGD ) SYSTEMS, OR SCRUBBERS, HAVE OPERATED EFFICIENTLY, ECONOMICALLY AND RELIABLY, HELPING
OUR CUSTOMERS MEET PERMIT REQUIREMENTS WHETHER AS A
NEW SOURCE OR RETROFIT APPLICATION. CURRENT DESIGNS CAN
ACHIEVE MORE THAN 

# 99% REMOVAL OF SO 2 

### . IMPROVEMENTS
IN B & 

### W’s WET SCRUBBER DESIGN AND AUXILIARY EQUIPMENT HAVE
RESULTED IN SYSTEM AVAILABILITY GREATER THAN 

# 99.5%

.largest network of field service engineers to support project development, project execution, and long-term operation and maintenance. We also conductextensive research and development ( R&D ) activities to continue product advancement. 

# Experience
**Original Equipment Supply** At the time of publication, B &W has provided wet FGD systems for a total scrubbed capacity of more than 60,000 MW. Through licensees in China and Germany, B &W wet FGD technology has been utilized for an additional capacity of more than 45,000 MW. **Upgrades** B & W has also improved the performance of more than 8,000 MW of non-B &W wet FGD systems by replacing the original absorber internals with our absorption tray technology and through forced oxidation conversions. Benefits have included improved SO 2 removal, reduced absorber pump power 

# Scope of supply

B & W is a full-scope supplier. In addition to flue gas absorbers, we supply reagent preparation systems, dewatering systems and related system equipment. We also provide complete construction services through our subsidiary, Babcock & Wilcox Construction Co., Inc. ( BWCC )

. B & W employs an experienced staff of design engineers, project managers, and the industry’s Current B & W designs are achieving 99% SO 2 removal with system availability greater than 99.5%.

3systems with two to four smaller boilers feeding one absorber and three larger units feeding two absorbers. 

# Choice of reagents

B &W has designed FGD systems using a variety of reagents. While most of our experience is with limestone, designs have utilized lime, magnesium-enriched lime, and soda ash. Limestone-based systems using organic acid enhancement have also been provided. 

# Oxidation experience All new wet FGD systems are designed and supplied with forced oxidation. Existing units can also be converted to forced oxidation. This beneficial process converts calcium sulfite to calcium sulfate and improves scrubber operation while providing a marketable gypsum bypr oduct. B & W has more than 16,000 MW of commercial units successfully operating with in situ forced oxidation systems. In addition, we have 2,800 MW of commercial units operating with specialized forced oxidation systems that are separate from the absorber reaction tank, most notably on magnesium-enhanced lime systems. 

# Advanced design bene fits

B & W continues to optimize its FGD systems by refining the technology to improve SO 2removal efficiency, improve longterm operating reliability, and reduce capital and maintenance costs. As an indication of our constant efforts to improve our designs, we currently have more than 40 patents involving wet FGD technology. As a full-scope supplier, B & W can provide complete FGD systems including reagent preparation, dewatering and other system equipment as well as a wide range of multi-pollutant control technologies.

consumption and maintenance costs, reduced limestone consumption, the elimination of costly additives, decreased landfill requirements, and the opportunity to provide a marketable byproduct. **Fuel Experience** B &W operating experience encompasses a complete range of fuels including bituminous, subbituminous, Powder River Basin (PRB), lignite and brown coals. We have also provided systems for heavy oil and Orimulsion ® fuels. **Large, Single Absorbers** As the technology of wet FGD systems has improved, typical units have a single absorber module. B & W absorber modules up to 1,300 MW are available. Absorber design and reliability allows many utilities to treat the flue gas from multiple boilers with one absorber. To reduce project costs B & W and our licensees have provided

4

# C B & W’s wet FGD systems operate efficiently, economically and reliably on a variety of worldwide fuels to help our customers meet permitting and operating requirements.Conical Outlet

Interspatial Spray Levels SO 2 and Flue Gas In

Gas Distribution Trays
Oxidation Zone

Slurry Agitators Oxidation Air Supply

Recirculation Pumps Clean Flue Gas Out

Moisture Separators/ Mist Eliminators 

# The B &

# W Absorber

Babcock & Wilcox Absorber

6 

# Absorption tray system A proven design for high SO 2 

# removal

B &W’s absorber design features provide the highest levels of SO 2 removal, reduced operating costs and significant reductions in maintenance costs compared to other technologies. These benefits allow our customers to stay competitive with today’s increasingly more stringent environmental requirements. 

# Absorber design

B &W’s absorber module is a counter-current flow design. Slurry is sprayed downward from a series of headers and nozzles and scrubs the flue gas as it moves upward through the absorption tray and spray zone. The control system automatically adjusts the feed of fresh reagent to achieve an outlet SO 2 emission limit or the required SO 2 removal efficiency.

B &W’s absorber tray system serves the dual purpose of providing gas/liquid contact for SO 2 absorption and more uniform distribution of flue gas across the tower. The gas rises through the absorber, contacting a froth of slurry on the tray. This action results in efficient contact of gas and reagent throughout the absorber.
B &W absorbers use one or two trays depending upon the fuel and specified requirements for SO 2 removal and operating parameters. The tray provides uniform gas distribution and effective gas/slurry contact. As an economic design for high efficiency, B &W offers our dual-tray technology for certain applications. Table 1 summarizes the benefits of the B &W tray absorber tower design. The slurry and the flue gas must be uniformly distributed across the absorber tower’s cross-section for optimum SO 2 removal. An efficient spray header and nozzle system is used to evenly distribute the liquor, while the tray distributes the gas flow. As determined by both physical and computer modeling, the gas side pressure drop induced by the slurry sprays is not sufficient by itself to adequately distribute the flue gas at the base of the spray zone. In open spray towers, uniform gas distribution is not achieved as effectively.
The B &W tray design effectively achieves uniform gas distribution, which becomes even more criticalB & W’s absorption tray provides for uniform gas flow and maximizes SO 2 removal. This photo shows a tray after two years of continuous service. **TABLE 1** 

## EXAMPLE ABSORBER COMPARISON **Unit Size : 617 MW SO 2**  **Inlet : 1,100 ppmdv Reagent : Limestone**  **SO 2**  **Removal : 97.6% 2 Trays 1 Tray Open Tower**  L/G 56 82 108 P, in. wc 10.2 8.2 7.0 Pump Flow, gpm 34,500 50,000 66,000 Fan/Pump Power, kw 6,470 6,560 7,470 Power Base +90 +1,000 Pump/Header Cost Base +$400k +$700k

7 High gas velocity in spray area is less effective. Uniform gas distribution through spray zone(s) results in more effective and efficient SO 2 removal.

in larger-diameter spray absorber towers. Without a tray, some zones of the absorber have poor gas distribution, which results in zones of either inadequate or excess slurry and reactant. With the tray, flue gas is uniformly distributed for the most efficient SO 2 removal. The tray is rugged, made from an alloy steel. The tray is also used as a convenient inspection and maintenance platform when using appropriate planking. Costly and time-consuming scaffolding is not required.
B & W’s tray design has been proven through extensive laboratory testing and modeling and many years of successful operation. B & W uses both advanced numerical modeling and physical modeling to design the most efficient wet flue gas desulfurization systems. a) Wet FGD Without B & W Tray b) Wet FGD With B & W Tray

Outlet Outlet Gas Velocity Magnitude

(ft/s) 30 28 26 24 22 20 18 16 14 10 8 6 4 2 0

Slurry Level Slurry Level Inlet Inlet Mist Eliminator 2
Mist Eliminator 1

Spray Header 2 Spray Header 1 Mist Eliminator 2
Mist Eliminator 1

Spray Header 2 Spray Header 1 TrayTwo levels of moisture separators effectively prevent slurry carryover and deposition in the downstream flue.

Multiple side-entering agitators on B & W’s absorber tower provide uniform slurry mixing.

8 test the performance of moisture separators in our hydraulic model. We also work closely with our suppliers in the development of advancements to moisture separator technology. 

# Patented inlet awning

B & W’s patented inlet awning design prevents the buildup of deposits in the absorber inlet flue. The awning deflects the falling slurry away from the inlet, shifting the wet-dry interface out into the absorber away from the inlet flue. This design provides high reliability and lower maintenance costs.



# Tank agitators Slurry in the recirculation tank is agitated to keep the solids in suspension. B &W’s standard design allows for operation with one of the agitators out of service for high system reliability. 

# Patented interspatial headers
Achieving overlapping spray coverage with an effective spray header design is critical for optimal SO 2 removal performance. B & W’s patented interspatial header technology allows the location of two spray headers at the same elevation while maintaining full overlapping coverage with one or both spray headers in service. The use of interspatial spray headers results in a shorter absorber tower, reduced pump power, lower building height, less external recirculation piping, and easier nozzle inspection and maintenance. 

# Moisture separ ator Efficient moisture separation is essential to prevent slurry carryover and deposition in the flue downstream of the module. B &W absorbers utilize two levels of chevron-shaped moisture separators that are rugged in design and have a history of low replacement. We have performed extensive R&D to optimize gas flow distribution, develop velocity profiles, and Deposit buildups in the absorber inlet flue are reduced by B & W’s patented inlet awning.

# Materials of construction

B & W can supply absorber modules in a variety of materials for dependable operation and reliability: rubber and flake glass lined, stainless steel, and duplex stainless. Concrete and tile designs can also be supplied. Abrasion-resistant fiberglass reinforced piping ( FRP ) or alloy piping can be used for internal spray headers. Abrasion-resistant materials are used for the spray nozzles. External piping is typically FRP or rubber-lined carbon steel. 

# Multi-pollutant capability

B &W provides a full range of flue gas cleaning equipment. Our products include wet and dry precipitators, baghouses, wet and dry scrubbers, reagent injection systems for SO 3 and acid mistcontrol, and a variety of technologies for the control of mercury. The B & W wet scrubber provides control of several pollutants in addition to SO 2 . Filterable (solid) particulate is removed in the wet scrubber. The wet scrubber removes 40

- 90% of the flyash entering the scrubber, depending upon the ash inlet loading and the type of upstream particulate collector.
Acid mist ( H 2 SO 4 ) is removed in the wet scrubber. The removal is dependent upon a number of operating conditions such as gas temperature, gas humidity, inlet concentration, etc. H 2 SO 4removal in wet scrubbers ranges from 35

- 70%. Mercury is also removed in the wet scrubber. Using B &W’s patented and proprietary additives, a minimum of 90% removal of oxidized mercury can be achieved. Ongoing research at the time of this publication indicates the potential for at least 20% removal of elemental mercury. 

# Extensive R&D activities for improved performance

B & W is continuously working to improve our wet scrubber product line. Our research center is equipped with a wet scrubber pilot plant. The flue gas is supplied by a small boiler unit capable of firing a variety of coals, liquid and gaseous fuels. B &W also has an advanced hydraulic model that is used to study tray and spray fluid hydraulics and mist eliminator carryover.

Through extensive research and development, B & W scientists continually strive for product improvements to help our customers reduce emissions.

9 B & W’s interspatial spray header design provides complete spray coverage for optimal performance and easier maintenance.systems for mercury and SO 3 control, low NO xcombustion systems, and selective catalytic and non-catalytic reduction systems for NO xcontrol. In addition, B &W provides a complete package of aftermarket services including engineered equipment upgrades, startup and commissioning, performance testing and monitoring, field engineering and replacement parts. 

# Full

- Scope Integration

B & W FGD systems are backed by an experienced staff of design engineers, project managers and a network of field service engineers.

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# Modularization

B & W designs its scrubber systems with modularization in mind. Components are manufactured to minimize on-site labor requirements, particularly in locations with limited laydown area. This technique significantly reduces both the project schedule and construction costs and represents an important advancement in manufacturing and construction technology. 

# Project management Many times, a project calls for new ways of thinking. B & W’s innovation goes beyond traditional project management and vendor/supplier relationships. Innovative approaches, such as strategic alliances, can allow us to collaborate with our customers and key suppliers on ideas and solutions and ultimately share in the cost savings that can result from such an arrangement. Effective communication and trust are vital to make any project a success. 

# Total-scope services

B &W provides total-scope services, such as project engineering and management, component fabrication, and installation of complete environmental emissions control equipment. Our environmental equipment capabilities include fabric filter baghouses, precipitators, sorbent injection B & W is the only FGD supplier with a full capability construction company operating as a subsidiary on the same campus. Complete project integration, from concept to commercial operation, is necessary to control costs and schedule and is achievable through the team of B & W and BWCC.

# Q R S **MIDWESTERN U.S. UTILITY, UNIT 8**

NOMINAL BOILER CAPACITY NOMINAL SCRUBBER CAPACITY ( ACFM ) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION FUEL REAGENT OXIDATION METHOD 550 MW 2,127,000 2764

97 APRIL 2007 PULVERIZED COAL LIMESTONE

FORCED **PROGRESS ENERGY, ROXBORO UNIT 2**

NOMINAL BOILER CAPACITY NOMINAL SCRUBBER CAPACITY ( ACFM ) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION FUEL REAGENT OXIDATION METHOD 670 MW 2,079,000 1977

97 APRIL 2007 PULVERIZED COAL LIMESTONE

FORCED **AMERICAN ELECTRIC POWER, MITCHELL UNITS 1 AND 2** 

NOMINAL BOILER CAPACITY ( combined ) NOMINAL SCRUBBER CAPACITY (ACFM, per unit ) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION

FUEL REAGENT OXIDATION METHOD 1600 MW 3,238,700 1990

98 JAN 2007 ( Unit 2 ) APRIL 2007 ( Unit 1 ) PULVERIZED COAL LIMESTONE

FORCED

**PROGRESS ENERGY, ASHEVILLE UNITS 1 AND 2**

NOMINAL BOILER CAPACITY (combined ) NOMINAL SCRUBBER CAPACITY (ACFM , per unit) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION

FUEL REAGENT OXIDATION METHOD 400 MW 715,429

1990

97 NOV 2005 ( Unit 1 ) MAY 2006 ( Unit 2 ) PULVERIZED COAL LIMESTONE

FORCED **NEW BRUNSWICK POWER, DALHOUSIE UNITS 1 AND 2**

NOMINAL BOILER CAPACITY (combined ) NOMINAL SCRUBBER CAPACITY ( ACFM , per unit ) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION FUEL REAGENT OXIDATION METHOD 315 MW 1,078,400 2300

90 DEC 1994 ORIMULSION

LIMESTONE

FORCED **MIDWESTERN U.S. UTILITY, UNITS 2 AND 3**

NOMINAL BOILER CAPACITY ( combined ) NOMINAL SCRUBBER CAPACITY ( ACFM , per unit ) INLET SO 2 CONCENTRATION ( PPM ) PERCENT SO 2 REMOVAL COMMERCIAL OPERATION

FUEL REAGENT OXIDATION METHOD 661 MW 2,698,000 2550

97 DEC 2006 ( Unit 3 ) MAY 2007 ( Unit 2 ) PULVERIZED COAL LIMESTONE

FORCED ® 

## Recent B &

## W Wet FGD ProjectsBabcock & Wilcox Power Generaon Group, Inc. 20 S. Van Buren Avenue Barberton, Ohio 44203 USA Phone: 330.753.4511 Fax: 330.860.1886
The informaon contained herein is provided for general informaon purposes only and is not intended nor to be construed as a warranty, an offer, or any representaon of contractual or other legal responsibility. Orimulsion is a trademark of Bitumenes Orinoco, S.A. © 2007 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. E101 - 3167A2KA0G Babcock & Wilcox Power Generaon Group, Inc. is a subsidiary of The Babcock & Wilcox Company (B&W). Established in 1867, B&W is a world leader in providing steam generang and emissions control equipment, nuclear operaons and components, and defense program management services. For more informaon, or a complete lisng of our sales and service offices, call 1-800-BABCOCK (222-2625), send an e-mail to info@babcock.com, or access our Web site. www.babcock.com



# HELPING OUR CUSTOMERS PROVIDE CLEAN POWER
Working with our customers, B&W provides worldwide leadership in environmental products and services by applying the best technology through innovation, responsiveness and employee commitment.