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W P C A
Worldwide Pollution
Control Association
WPCA-Duke Energy
FF/HAPS Seminar
October 12-13, 2011
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© 2005 by General Electric Company. All Rights Reserved.
WPCA-Duke Energy Pulse-Jet Fabric Filter Training Robert Brinkley Babcock & Wilcox Tim Stark GE-Fabric Filter
GE Proprietary 2 2
Typical SDA System Schematic
Stack
Induced Draft Fan
Hoppers
Baghouse
Ash/Reagent Silo
Silo Baghouse
SDA/Slurry Tower
Reheat Section
Economizer
Steam Generator
Air Heater
GE Proprietary 3 3
Hot Gas Market APC Trends
Historically, 95% of applications utilized Reverse Air collector designs:
• Woven Fiberglass bags
• Woven Fiberglass with PTFE
• 2:1 air-to-cloth ratio
• 11.5" x 30' filters (29cm x 9m)
• 4 – 8 year filter life
• Large footprint housing
GE Proprietary 4 4
Hot Gas Market APC Trends
Utility Boiler 500,000+ ACFM
Municipal Solid Waste Incineration
16 MW – 65,000 ACFM
Coal-fired Industrial Boiler
110,000 ACFM
In the past 10 years, the trend is moving to Pulse Jet collectors (approximately 80% of applications):
• Felt used for under 375°F (190°C)
• 2.5-3.5:1 Air-to-Cloth ratio
• 3 – 6 year filter life
• Smaller housing footprint
Proprietary and Confidential
Pulse-Jet Baghouse
.5
GE Proprietary 6 6
Three Types of Cleaning Systems
• High Pressure/Low Volume
– 8-7bar (80-100psi)
• Medium Pressure/High Volume
– 2-3bar (30-45psi)
• Low Pressure/High Volume
– 1bar (15psi)
GE Proprietary 7 7
Medium Pressure/High Volume
• 2.5" to 3" pulse valves
• Typically round filters with cages
• Do not use traditional venturis
• Filters: 125-159mm x 3000-6000mm 5"-6.25" x 10'-20‘
• Requires an air compressor
Proprietary and Confidential
Pulse Jet Baghouse
Clean
Gas Outlet
Dirty
Gas Inlet
Proprietary and Confidential
Pulse-Jet Designs
© 2011 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .9
Bags & Cages Bags & Cages
Hatch Design Plenum Design
Proprietary and Confidential
Pulse Jet Fabric Filter
Flue
Gas Inlet
Clean
Gas Outlet
8 and 10 m
bags
Proprietary and Confidential
Pulse Air System
Tubesheet
“J” Pipes
Blow Pipes
Bag/Cage
Proprietary and Confidential .12
Pulse Jet Baghouse
Pulse Valves
Pulse Header
Solenoid Boxes
GE Proprietary 13 13
Medium Pressure Cleaning System
GE Proprietary 14 14
Cleaning Systems
GE Proprietary 15 15
Cleaning Systems
GE Proprietary 16 16
Medium Pressure / High Volume Pulsing
• Standard pulsing system
• 14" nominal diameter compressed air header
• 3" diameter pulse valve & blowpipe
• Blowpipes typically include nozzle extensions at each blow hole
• 3" diameter pulse valve @ 30 psi consumes 140 scfm max. pulse interval: 6 seconds duration: 230ms volume: 14.03 scfm/pulse
• Horsepower required to compress air to 30 psi: 15.26 Hp = 11.38 Kwh
• Formula: HP = 0.2267Q [[PSI/14.7+1] 0.283 –1] + 30% safety factor
GE Proprietary 17 17
Cleaning Systems
GE Proprietary 18 18
ACFM
Actual Cubic Feet of gas per Minute
The volume of the gas flowing per unit of time at the operating temperature, pressure and composition.
(also measured in cubic meters per hour)
GE Proprietary 19 19
Air-to-cloth ratio = acfm÷total filter area
(Filter dia. X length x 3.14) = filter area
Total # filters x filter area = total filter area
Air-to-Cloth calculations
GE Proprietary 20 20
Air-to-Cloth ratio (filter rate)
Type of Filter Maximum Recommended Cleaning System Air-to-Cloth Ratio
Shaker 3.0 0.91
Reverse Air 2.5 0.76
Pulse-Jet:
A. Cylindrical Filter Bags:
-For elevated temp 2.5-4 .76-1.22
B. Pleated Filters (Non-Paper Media) 3.5 1.07
C. Pleated Filters (Paper Media) 2.0 0.67
Imperial Metric
GE Proprietary 21 21
Can velocity
In a pulse jet dust collector with the filter elements suspended from the tubesheet and a hopper level inlet, Can Velocity is the upward air stream speed passing between the filters calculated at the horizontal cross-sectional plane of the collector housing at the bottom of the filters.
GE Proprietary 22 22
6:1 AC Ratio
8' bags
6:1 AC Ratio
10' bags
6:1 AC Ratio
12' bags
6:1 AC Ratio
6' bags
Can velocity
GE Proprietary 23 23
6:1 AC Ratio
12' bags
6:1 AC Ratio
8' bags
6:1 AC Ratio
10' bags
6:1 AC Ratio
6' bags
Industry Standard
with hopper inlet:
<300 fpm
Point of measuring
can velocity (bag
bottom)
L
W
Can velocity
GE Proprietary 24 24
GE Proprietary 25 25
Diaphragm valve
GE Proprietary 26 26
Manifold
GE Proprietary 27 27
Solenoid valve with bleeder tube or integral to valve
GE Proprietary 28 28
Blowpipe
GE Proprietary 29 29
Tubesheet (cell plate)
GE Proprietary 30 30
Bags
GE Proprietary 31 31
Cages
GE Proprietary 32 32
GE Proprietary 33 33
GE Proprietary 34 34
GE Proprietary 35 35
GE Proprietary 36 36
Valve / solenoid operation
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .37
Pulse Air Headers
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .38
Pulse Jet Valves
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .39
Inside a Compartment
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .40
Compartment Outlet Dampers
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .41
Bypass Dampers
GE Proprietary 42 42
GE Proprietary 43 43
GE Proprietary 44 44
.05
.15
Time (standard for 1.5” DD valve, .250 sec target for 3” valve)
Valve Energy
GE Proprietary 45 45
Clean-on-Demand system
High-Low set points at no greater than 1" apart… Ideal is no more than 0.5"
GE Proprietary 46 46
3 1/2 - 4
GE Proprietary 47 47
Gauge Connection Modification
Clean Air Plenum
Gauge
Copper or Plastic Tubing
Pipe Cap Reducer
12" Pipe Nipple (or shorter)
2 1/2" diameter Weld Dusty Air Plenum
or Hopper Wall
Tubesheet
GE Proprietary 48 48
Cleaning sequence
1 4 7 10 2 5 8 3 6 9
GE Proprietary 49 49
Multi-Compartment Cleaning
GE Proprietary 50 50
Common Inlet Design
Inlet baffle directs airflow down into hopper.
Collected material can swirl upward, causing heavier than design grain-loading.
Narrow hoppers and nearby bag bottoms may experience abrasion damage.
Proprietary and Confidential
Photo of Bags as Viewed from the Hopper
1352 Bags
Per Compartment
GE Proprietary 53 53
Abrasion failure: Bottom of filter bags located directly in line with inlet gas stream Excessive movement of filters causing bag-to-bag abrasion
GE Proprietary 54 54
GE Proprietary 55 55
GE Proprietary 56 56
Blowpipe problem
GE Proprietary 57 57
GE Proprietary 58 58
GE Proprietary 59 59
GE Proprietary 60 60
GE Proprietary 61 61
Blowpipe manifold/bag seam alignment
GE Proprietary 62 62
GE Proprietary 63 63
Bag house refurbishment Fabric characteristics and suitability for power generation applications
* Sensitive bag-to-cage fit
** Fair with chemical or acid-resistant finishes
*** Must oversize bag for shrinkage for temperatures above 450°F (232°C)
Polypropylene Polyester Acrylic Fiberglass Aramid PPS P84 *** Teflon® ***
Max. continuous operating temp.
170° F (77° C)
275° F (135° C)
265° F (130° C)
500° F (260° C)
400° F (204° C)
375° F (190° C)
500° F (260° C)
500° F (260° C)
Abrasion Excellent Excellent Good Fair* Excellent Good Fair Good
Energy absorption Good Excellent Good Fair Good Good Good* Good
Filtration properties Good Excellent Good Fair Excellent Excellent Excellent Fair
Moist heat Excellent Poor Excellent Excellent Good Good God Excellent
Alkaline dust Excellent Fair Fair Fair Good Excellent Fair Excellent
Mineral acids Excellent Fair Good Poor** Fair Excellent Good Excellent
Oxygen (>15%) Excellent Excellent Excellent Excellent Excellent Poor Excellent Excellent
Relative cost $ $ $$ $$$ $$$$ $$$$$$ $$$$$$ $$$$$$$
GE Proprietary 64 64
Filtration Application Conditions Where PPS Excels
• Continuous temperature is 375°F (192°C) or less
• Oxygen content is 15% or less
• Sulfur is present in the fuel, and/or oxides of sulfur are present in the flue gas
• Moisture is present in the flue gas
• Dew-point excursions take place
GE Proprietary 65 65
Bag and cage selection
Standard recommended bag pinch
Dependant upon fabric selection:
Bag
Cage
Precoating New Filters
GE Energy
Copyright© GE 2004
GE Proprietary 67 67
New fabric receives more airflow
• New fabric accepts airflows in the range of approximately 20 to 50 cfm.
• Filter bags that have been in service and have a good porous dustcake have airflows at 5 to 10 cfm.
• The new filters will be subjected to three times the airflows as the bags that are currently in service, causing potential damage early in the bag’s life.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .68
PJFF Theory
Filters out particulates
Filter cake on bags contributes about 20% of SO2
reduction
SO3
HF
HCl
SO2
“Clean Gas”
GE Proprietary 69 69
Unprotected new
fabric interstices
work like miniature
venturis to accelerate
airflow through the
fabric, causing
particulate
impingement.
Unprotected fabric
GE Proprietary 70 70
Initial dustcake requirements:
1. Porous, ensuring high airflows
A. Range of particle sizes
B. Varying particle shape
2. Provide a uniform coat.
(1/16” to 1/8”)
3. Material should be neutral (pH).
4. Safe to handle.
GE Proprietary 71 71
Protected
Unprotected
Artificial Dustcake
Embedded Particles in Interstices
New fabric protection & porosity
GE Proprietary 72 72
Pre-coat injection
High on hopper wall 3” diameter
x 6” long pipe nipple. Neutralite®
can be injected here.
3” diameter x 6” long pipe nipple
on inlet ductwork/elbow.
Neutralite® can be injected here.
Discharge Hose
Vacutrans™
Compressed Air
Connects Here
Poke hole port, usually 3”
or 4” dia. Location is too
low to inject Neutralite,
not enough air volume to
maintain velocity needed
to carry Neutralite to top
section of filter bags.
Vacuum
Hose
Airlock or
slide gate.
To ash removal
system.
Hopper door lockout
procedures usually won’t
allow this access door to be
open while dampers are
open or fan is running.
Insulation and
sheet metal
lagging.
Hopper Side Wall
Proprietary and Confidential
Apply Pre-coat Material into Hopper Door
© 2007 The Babcock & Wilcox Company. All rights reserved. The Babcock & Wilcox Company.73
Proprietary and Confidential
Startup Pre-Coated Bags
•Season Bags
•2 pounds on a 10
Meter x 150
mm Bag
•Material
1. Limestone
2. Fly ash
3. Aluminum
Silicate
4. Diatomaceous
earth
© 2007 The Babcock & Wilcox Company. All rights reserved. The Babcock & Wilcox Company.74
Proprietary and Confidential
Apply Pre-coat Material into Hopper Door
© 2007 The Babcock & Wilcox Company. All rights reserved. The Babcock & Wilcox Company.75
Proprietary and Confidential
Apply Pre-coat Material into Hopper Door
© 2007 The Babcock & Wilcox Company. All rights reserved. The Babcock & Wilcox Company.76
Leak Detection
GE Energy
GE Proprietary 78 78
Purpose
• Identify holes in filters
• Check for proper installation
• Detect structural air leaks
GE Proprietary 79 79
Key information
• Clean Air Plenum Access
• Cloth Area
• Injection Location
GE Proprietary 80 80
Injecting Leak Detection Powder
GE Proprietary 81 81
Keys to successful test
• Shut off cleaning system
• Fan in operation
• Inject powder (1lb per 1000 sq ft of cloth)
• Shut off Fan after sufficient time for powder to disperse
• Test with light
GE Proprietary 82 82
Powder collects around air leaks
BHA Visolite® Leak Detection System
GE Proprietary 83 83
Options:
BHA Visolite® colors:
Monchromatic lights:
GREEN ORANGE PINK YELLOW
Proprietary and Confidential
Startup
•Preheat hopper
with heaters 24
hours prior to startup
•Close all doors
•Verify Pulse Jets
are operational
•Monitor
Temperatures & DP
© 2007 The Babcock & Wilcox Company. All rights reserved. The Babcock & Wilcox Company.84
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .85
PJFF Overview Screen
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .86
PJFF Control
PJFF starts cleaning when the baghouse differential
pressure exceeds the “start” setpoint. Stops cleaning
when the dP drops below the “stop” setpoint.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .87
PJFF Control – Groups
Whole baghouse doesn’t clean at once!
Cycles through pulse headers in “groups”.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .88
PJFF Control - Pulse Air Header Sequencers
One sequencer for each header.
The DCS gives the sequencer a
command to start firing pulse valves
when it is time to clean.
Two valves per header pulse at the
same time.
30 valves on a header, so it takes 15
pulses to complete a header.
Pulses are 10 seconds apart.
The last pulse valve on a sequencer
sends a “sequencer complete” signal
back to the DCS.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .89
PJFF Control
Once all 5 headers in a group say they are complete,
the DCS moves on to the next group.
Just because a group is “ready”, doesn’t mean it is
pulsing!
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .90
Monitoring the System
Usually, not much to look for.
BUT – If a pulse valve sticks open or pulse header air
supply line ruptures:
Typically the PJFF air compressor pressure indication will
drop a few psi and become erratic.
If the leak is bad enough, the pulse headers will stop firing
due to low pulse header pressure. This is VERY BAD
because differential pressure can rise rapidly without
cleaning at full load!
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .91
Hunting a Bag Leak
Typically, an opacity spike will occur when the leaking
bag is pulsed.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .92
Hunting a Bag Leak
Trend data showed this leak was likely in PJFF-A,
group B.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .93
Hunting a Bag Leak
The location of the leak can
be quickly narrowed down to
a particular compartment
header.
After the offending group is
identified:
Manually pulse each of the
headers in the group one at a
time and wait for an opacity
spike to occur.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .94
Hunting a Bag Leak
The header of the leaking bag is found!
So, we’ve got it down to 500 out of a possible 22,000
bags.
That’s still a lot of bags. What is the next step?
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .95
Hunting a Bag Leak
The leaking bag can usually be identified easily once
the compartment is locked out and entered. BUT –
only if previous leaks in the compartment have been
thoroughly cleaned up!
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .96
Repairing a Bag Leak
The blow pipe is removed, the bag cage is pulled out,
and the broken bag is extracted.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .97
Repairing a Bag Leak
This bag was damaged by rubbing against the
compartment wall.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .98
Repairing a Bag Leak
The area is vacuumed up, a new bag is installed, and
the cleaned and inspected cage is re-inserted.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .99
Bag Leaks – Final Thoughts
Bag leaks are relatively painless to identify and
correct – IF opacity spikes are checked regularly and
compartments are thoroughly cleaned when bags are
replaced.
Flue gas velocity in the compartments is very low.
The ash path from bag to outlet damper won’t just
sweep itself clean – it must be vacuumed.
Proprietary and Confidential © 2008 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .100
Questions ?
Proprietary and Confidential
Bag Attachment to Tubesheet
.101 © 2011 Babcock & Wilcox Power Generation Group, Inc. All rights reserved.
Proprietary and Confidential
Bag Cages
Process gas flows from the outside to the inside of the filter
bags. Bag cages are installed inside each bag to prevent
their collapse during operation
Bag Cage Splice
Proprietary and Confidential
Pulse Valves and Pilot Solenoids
•Compressed air is sequentially discharged to each blowpipe through a pilot controlled pulse valve. The pulse valve is a double diaphragm valve. The pulse valve is controlled using a normally closed electrically operated solenoid air valve
Pulse Valve
Pulse Valves
Proprietary and Confidential
10 meter Filter Bags
© 2011 Babcock & Wilcox Power Generation Group, Inc. All rights reserved. .104
Surface Area -
8,704 filter bags
10 - meter length?
10 – Acres
435,600 ft2