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8/11/2019 4. WESP Round Table Presentation October 2010
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Operating Experience of Wet
Electrostatic PrecipitatorsSam Kumar & Adel Mansour
Babcock & Wilcox Company, USA
Round Table Sulfuric Acid Conference
Puerto Varas, Chile
October 17-20, 2010
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Typical Acid Product Specifications
Hg PPM 0.5
As PPM 0.5
Se PPM 0.5
Pb PPM 1.0
As+Cu+Ni+Cd PPM 1.0
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Venturi Scrubber Performance Alone
Is Not Enough
To achieve low levels of arsenic emissions
highly efficient wet ESPs will be required
High level of fine particulate control is needed
High level of sulfuric acid mist control is needed
Maximum practical particulate control ahead
of wet ESPs ( in the dry ESPs and venturis ) will
reduce maintenance requirements of WESPs
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B&Ws Wet ESP Technology Milestones
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.4
The B&W Company offers WESP products based on the technology, experience and
know-how of Western Precipitation, Joy, Fluid Ionics, and FLS.
B&W licensed all of FLS WESP technology for all applications
on a world-wide basis
B&W acquired the pollution control business of Joy Environmental, which
included that of Joy Western and Western Precipitation
1907
1995
2004
2003
B&W entered into a contract with FLS to supply WESPs for supply of (2)
power plant capturing sulfuric acid mist ESPs for a power plant complex
totaling 1,050 MW of generation
Western Precipitation installs their first wet precipitator on a smelter in Selby
California
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Several B&W wet ESP reference plants
in the Americas
Groupo Mexico, SPCC, Ilo, Peru
CODELCO El Teniente, Chile
Groupo Mexico, Mexicana DeCobre, Mexico Cominco Trail, BC, Canada
Xstrata Horn, Canada
Xstrata CEZinc, Canada Xstrata Falconbridge, Canada
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Lead wet ESP Codelco EL Teniente
Casing bottom and middle section installation
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Codelco EL Teniente
ChileInstallation of lead tubesheet
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Grupo Mexico-Southern Peru Copper ILO
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Grupo Mexico-Southern Peru Copper, ILO
Lower High Voltage Discharge Electrode Frame
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Wet ESP Tube/Rigid Electrode Design
Old Cells
New Cells
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WESP Corona Current Profiles
Acid Plant Inlet Outlet Electrode
Field* Field*
#1 15 23 Star wire#2 7.5 20 Star Wire
#3 15 15 Star Wire
#4 50 60 Pipe & Spike#5 60 - Pipe & Spike
* Corona current density in mA/1000 ft2
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Benefits Of Alloy Design
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.13
All alloy materials
Excellent electrical conductor
Continuous irrigation system not required
Robust construction permits periodic high pressure washing
Greatly reduces risk of damage by fire
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Hex Tube WESP Design Collector DesignMore Capacity in Same Footprint
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.14
More efficient
footprint with the
hex tube design
More collection surface using double sided collection
Replacement of round tube design with higher capacity alloy hex tube
B&W WESPs
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Rigid Discharge Electrodes in Alloy Design
Electrode DesignHigh Reliability
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.15
Self-supporting
rigid discharge
electrodes
Rigid pipe and nail construction = higher reliability
Higher corona producing discharge electrodes = superior WESP
performance
Self supporting arrangement, no insulators in the gas stream
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Hex Tube Design and Project Advantage
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.17
Modular designFits existing footprint
Flexibility in size (surface area)
Maintenance accessibility
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Transporting Collector Assemblies
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.19
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Lifting the Collector Assembly
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.20
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Installing the WESP Collector
Assembly
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.21
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Alloy WESP Units Replacement
for Lead Acid Mist Units
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.22
Customer A B1 B2 C
Application Pet-Coke
Calciner #3, #1& #2
Metallurgical
Sulfuric Acid Plant
#1
Metallurgical
Sulfuric Acid
Plant #2
Spent Acid Regeneration
WESP unit Cell #4, #1 (in
parallel) & #6
2 cells
(in parallel)
4 cells
(2+2 in series)
2 cells ( in series)
Foot print 16 ft x 17.5 ft
(each)
13.5 ft x 15.5 ft
(each)
13.5 ft x 15.5 ft
(each)
15 ft x 16 ft (each)
New WESP
No. of tubes
238 & 248 hex(each)
17 ft long tubes
150 hex (each)
17 ft long tubes
150 hex (each)
17 ft long tubes
248 hex (each)
15 ft long tubes
New WESP
collecting area
11,650 sq. ft.
(each)
7,395 sq. ft. (each) 7,395 sq. ft.
(each)
10,711 sq. ft. (each)
Old WESPNo. of tubes
98 lead tubes
(each)
(in parallel)
3 cells x 126 lead
tubes
(in parallel)
6 cells x 120 lead
tubes (3+3 in
series)
2 cells x 164 lead tubes
(in parallel)
Old WESP
collecting area
4,360 sq. ft.
(each)
4,950 sq. ft. each 4,712 sq. ft.
each
4,126 sq. ft. each
In Operation 1999, 2007 &
2008
2000 2000 2006
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Alloy WESP Replacement Example For
Lead Acid Mist Units
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.23
Customer B1 - Acid Plant
6 Old Lead WESP Modules with
Lead Tubes and Steel Shell
4 New HEX WESP Modules 150 Tubes
replaced 6 old Lead WESP modules
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Alloy Materials Suitability Curve
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
.24
Approximate Service Limits for Stainless Steels and Nickel-Base Alloys in Flue Gas Condensates and Acid Brines
at Moderate Temperatures (140176 F)
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Corrosion Study
Confirm Material SelectionCorrosion rack will include alloy coupons of 904L,
6%Mo, 654SMO, C276, C22, etc.
Test rack to be installed in operating unitsat the inlet and outlet sides
Test rack to be removed and analyzed after
test period
A key planning tool to switch to highperforming , economical alloy WESP design
2010 Babcock & Wilcox PowerGeneration Group, Inc. All rights reserved.
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Design and Maintenance Issues with
wet ESPs
Uniform Flow Distribution improves performance
Well aligned electrodes maximize power toWESP to maximize performance Poorly aligned electrodes lower power input
Increased sparking can lead to wire breakage and de-energizing of precipitator stage affecting performance
Insulators need to be kept warm and dry Premature tracking leads to low power
Damaged insulators can short the entire precipitatorstage
Purge air systems need periodic maintenance
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Perforated Plate Gas Flow Distributor
& Lower Flush Header
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Misalignment of Discharge Wire
limits operating power
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Insulators Must Be Clean & Dry
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Frequent Inspection & Maintenance is important
Acid and dust buildup on HV insulators
limits operating power
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V/I Curves: Indicative of Performance
and Maintenance Issues
Normal curve. After corona is formed,
current increases with increasing voltage.
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Voltage, kV
Current,ma
1
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V/I Curves (2)
Indicates resistance path to ground. May be due tocracked insulator or loose wire touching tube wall.
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Voltage, kV
Current,ma
12
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V/I Curves (3)
Indicates severe misalignment betweenemitting electrodes and collecting plates.
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Voltage, kV
Current,ma
12
3*
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V/I Curves (4)
Acts like increased radius of emittingelectrode (heavy deposits on rounded star
wire edges).
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Voltage, kV
Current,ma
12
3*
*4
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V/I Curves (5)
Indicates corona quenching due to severe spacecharge. Little increase in current with increasing
voltage because corona is not formed.
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60
Voltage, kV
Cur
rent,ma
12
3* 5
*4
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Conclusions
Dedicated maintenance can result in highly
improved reliability and availability of wet
ESPs
Alloy designs have been introduced to
replace lead WESPs
Designs show much noticeable improvements in
both performance and reliability
Better footprint efficiency can help retrofit and
expansion options considerably
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Thank You !! Local Babcock & Wilcox Contact in Chile
Technagent
Raul A. Sigren O.
Gerente General
Presidente Emazuriz 3262
Casilla 25Santiago 35, CHILE
mailto:[email protected]:[email protected]