Impulse Cleaning System

Maximize Coal-Fired Boiler Heat Transfer

Powerwave+*Impulse Cleaning System

GEs Impulse Technology

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Case StudiesPrevent ash build-up on boilersurfacesExtend time between outagesImprove heat rate transfer

Coal-Gen PresentationBoiler Fouling, On-line CleaningSolution Using Impulse Cleaning

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Trademark of General Electric Companyor its affiliates.2012 General Electric Company.All rights reserved.

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Improve Boiler Operations The path to helping enhance boiler operation and minimize maintenance expenses is closer than you

think and it starts with the Powerwave+ Impulse Cleaning System.

This revolutionary technology offers significant advantages over traditional cleaning methods such as:

Soot blowing

Rapping

Manual shaking

Blasting

High-pressure water washing

The Powerwave+ Impulse Cleaning System uses controlled, repeated impulses; cleaning is simply performed

online. Plus, you benefit from less tube wear and avoid wasting steam and water.

GEs powerful impulse technology augments and

potentially replaces cleaning systems used to

dislodge buildup and deposits on convection

surfaces in boilers and heat exchangers. This helps

provide high levels of penetration and dramatically

increases performance compared to alternative

methods such as soot blowing while helping

reduce operating costs and minimizing tube

and shield damage.

http://www.ge-energy.com/products_and_services/products/air_filtration/powerwave_plus_cleaning_system.jsp

Play the video below to see the effect of the Powerwave+ impulse wave.

How It WorksUsing groundbreaking jet propulsion technology, impulses form in a controlled, pulsed manner to direct

cleaning waves at surfaces where debris has collected.

The cleaning cycle results from a complex process but its fully managed by a simple, automated control

system. Heres how the cleaning cycle works:

Each burst delivers fuel and air to the combustion chamber

The mixture ignites and accelerates from subsonic to supersonic Mach 5 speeds

A supersonic impulse exits the Powerwave+ cleaner and travels into the boiler for cleaning

This process repeats up to 2 times per second

The strength and frequency of operation is adjustable, depending on the application

This shockwave weaves around obstructions and surrounding areas to provide more complete surface

contact. So you get a much cleaner boiler with optimized heat exchange and increased performance.

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Harness the Power of Online Cleaning Technology

Removes thick and stubborn ash deposits better than traditional cleaning methods

Reduces or eliminates the need for steam soot blowing

Enhances long-term operability

Reduces platenization

Fuel-efficient design offers low operating cost with minimal maintenance

Can integrate into plant control systems or operate in self-timed mode

Cleaner tubes increase heat transfer and overall efficiency of boiler

Operates online using proactive cleaning vs. requiring an outage and reactive cleaning

Extends time intervals between downturns caused by off-line cleaning, allowing more time

for production

Will not cause abrasion or erosion to boiler tube surfaces

Easy to install and maintain, with a small footprint that preserves valuable space

Uses only small amounts of compressed air, fuel and 110 VACv

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Powerwave+ Impulse Cleaning System

Frequency of cleaning cycle every 15 minutes to 1 hour

# of impulses per cleaning cycle 20 bursts, Typical

Output Power Level (Decibels) up to 180 dB

Material Stainless steel and cast malleable iron

Max Operating Temperature 1600 F (870C)

Weight 205 lbs. (93 kg)

Air Consumption 100-120 SCFM @ 70-90 PSI

(47-57 l/s @ 4.83-6.21 bar)

Fuel Consumption Call +1-800-821-2222

or +1-816-356-8400 for more information

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Powerwave+ Impulse Cleaning System

Controller Assembly:

External Dimensions ~12 x 9 x 6 to ~12 x 12 x 6.5 (~30.5 cm x 22.9 cm x 15.2 cm to ~30.5 cm x 30.5 cm x 16.5 cm)

Weight 23 lb. (10.4 kg)

Input Voltage 120/240 VAC

Input Frequency 50/60 Hz

Input Current 0.9 Amps @ 240 VAC/1.8 Amps @ 120 VAC

General:

Operating Temperature 120 to 158 F (48.9 to 70 C) cooling systems available for higher temperature areas

Operating Humidity Maximum 90% Relative Humidity, non-condensing

Operating Altitude Range 0-9842 ft. (0-3000 m)

Storage Temperature Range -68F to 122F (-20C to 50C)

Storage Humidity Range 20-50% Relative Humidity, non-condensing

Storage Altitude Range 0-9842 ft. (0-3000 m)

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Case Study 1

Prevent ash build-up on boiler surfaces

Challenge: This 220 MW unit uses 100% PRB coal. The T-fired boiler had heavy ash build up in the backpass.

The low temperature superheat (LTSH) section was fitted with an in-line tube arrangement that had ash

platenization in some areas and pluggage in others. Piling and ash accumulation were also a challenge in

the lower economizer section. Traditional sootblowers provided limited cleaning and used valuable steam

that caused corrosion and weakened boiler surfaces. The unit required an annual cleaning outage in order

to operate until the major scheduled outage.

Solution: Following a thorough evaluation,

GE recommended the installation of six

Powerwave+ Impulse Cleaning Systems to clean

the entire backpass of the boiler.

Results: After the installation of the Powerwave+

Impulse Cleaning Systems in early 2007, the plant

did not require an unplanned outage for boiler

cleaning and repair.

Other benefits included: 33F improvement in economizer outlet gas temperature

>25F improvement in air preheater outlet temperature

30% improvement in air preheater

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Case Study 2

Extend time between outages

Challenge: The 96 MW PRB coal-fired boiler was experiencing severe ash accumulation in its reheat

section. The plant had to take a major outage every year to clean the boiler in an effort to keep ash build up

in check. The primary goal for the plant was to keep this area as clean as possible and prevent costly

structural damage.

Solution: Powerwave+ Impulse Cleaning System technology delivers online high-energy impulse cleaning

that cleans transfer surfaces improving efficiency of coal-fired boilers.

Results: Installation of the Powerwave+ Impulse

Cleaning System has allowed the plant to maintain

boiler temperatures and pressures at desired levels.

Additionally, sootblowers were eliminated in two

locations and the time between scheduled cleaning

outages has been extended by 50% (from 12 to 18

months) due to the ongoing cleanliness of the boiler.

Key results Eliminated sootblowers in

two locations

50% increase in time between scheduled outages (from 12 to 18 months)

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Case Study 3

Improve heat rate transfer

Challenge: The combination of PRB coal and a tight fin design in the economizer was causing pluggage

in the boiler backpass. The existing cleaning methods for this 70 MW unit were inadequate and the plant

would become rate limited due to pressure and heat transfer efficiency loss.

Solution: Originally developed for jet propulsion, Powerwave+ Impulse Cleaning System technology can

increase energy output while reducing overall maintenance time and costs.

Results: Shortly after two Powerwave+ Impulse

Cleaning Systems were installed, the plant

experienced over a 70F drop in flue glass

temperature across the economizer and a 15F

drop across the air preheater. The boiler gained

a 0.5% improvement in heat transfer rate

following the Powerwave+ Impulse Cleaning

Systems start up.

If GE Powerwave+ cleaning

systems were installed on

10 percent of all coal-fired

boilers in the United States,

boiler operators could produce

an additional 1.09 million MWh of

electricity per year without

burning additional coal.

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Presented at Coal-Gen

Boiler Fouling, Online Cleaning Solution Using Impulse Cleaning See how impulse cleaning technology can offer effective non-erosive heat transfer surface cleaning

plus lower operation, maintenance and installation costs.

IntroductionDue to ever-increasing efforts towards maximizing availability and efficiency of utility and industrial

coal-fired boiler equipment and minimizing emission rates, there have been recent surges in research and

development in the areas of alternative fuels, chemical additives, active monitoring, combustion tuning, and

line cleaning.

Burning of solid hydrocarbon fuels results

in what is commonly referred to as slag-

ging and fouling of downstream heat

transfer surfaces due to the bi-products

of the combustion process. As heat trans-

fer surfaces are layered with or blocked by ash deposits, efficiency of heat transfer drops dramatically.

If left to continue to foul, the mass loading of the deposits, the redirected flow patterns, and/or the

excessive cleaning using current technology can lead to expensive operation and maintenance

expenditures for plants.

Looking at a sample 270 MW coal-fired power boiler, improvement of online cleaning that results in a 0.5%

efficiency gain can yield significant direct payback. This payback could equate to a maximum of 5,400 tons

reduction of coal consumption or the equivalent of 14,500 MWhr of electricity, 11,500 tons reduction in CO2

Significant payback is also seen in termsof reduced maintenance and cleaningcosts during outages, and less forced

outages throughout the year.

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emissions, and up to 50-ton reduction in SO2 emissions. Significant payback is also seen in terms of reduced

maintenance and cleaning costs during outages, and fewer forced outages throughout the year.

Impulse cleaning technology, a derivative of acoustic cleaning, has recently shown potential for dramatic

improvements in online cleaning of fouled surfaces when compared to existing cleaning systems being

used. This paper will present a brief background and description of impulse cleaning technology,

explanation of placement and operation, and highlight case studies from a sampling of plants that have

benefited significantly from the implementation of impulse cleaning systems to either augment or replace

existing soot blower cleaning systems.

BackgroundAcoustic cleaning technology in one form or another has been utilized in plants for over 3 decades to aid in

cleaning of heat transfer surfaces in boilers, filters

in baghouses, plates in electrostatic precipita-

tors, air preheater modules, catalyst in selective

catalytic reduction reactors, fans, silos, hoppers,

and various other pieces of equipment. Acoustic

cleaning systems typically utilize compressed air

to rapidly vibrate thick titanium diaphragm plates

to create sound waves or pressure waves. The

resulting sound waves are amplified and directed

into the equipment to be cleaned. The transverse

sound waves push and pull at the deposits, breaking them apart, and allowing gas flow or gravity to carry

the deposits away from the surfaces. Typically, a dry, friable, ash-deposit is the most receptive to this type of

cleaning power. There have been numerous papers written and presented over the years regarding

A significant benefit of acoustic orimpulse cleaning systems over sootblowers is that they can be operated

very aggressively in terms of theircleaning frequency per day withoutcausing the tube erosion associated

with soot blowers.

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the benefits of acoustic cleaning technology over other types of cleaning systems such as rappers, soot

blowers, shakers, reverse-air systems, vibrators, and air cannons.

Impulse cleaning technology, the main subject of this paper, utilizes intense pressure waves of magnitudes

more intense than acoustic cleaners can emit, to provide significantly more complete and far reaching

cleaning of heat transfer surfaces and the ability to address more sticky deposits typically outside the range

of acoustic cleaning capabilities. The method utilized to create these impulse pressure waves vary greatly,

including just flexing a diaphragm plate with air as described for acoustic cleaners. In most cases, the

impulse or shock waves are created through the rapid combustion, or detonation, of a charge of

fuel/oxidizer in such a manner to direct the resulting impulse wave into the heat transfer surface to be

cleaned. The basis for this rapid combustion technology has roots deep within the aerospace research and

development field (where high-throughput, pressure-rise combustion has the potential to radically change

the design of future propulsion systems). A shock wave, or impulse wave, is an intense single pressure pulse

characterized as having an immediate pressure rise followed by a sharp pressure-decay. This pressure wave

is utilized in impulse cleaning systems to physically break apart agglomerations and facilitate them to move

on through the process, without damaging the heat transfer and surrounding structure.

A significant benefit of acoustic or impulse cleaning systems over soot blowers is that they can be operated

very aggressively in terms of their cleaning frequency per day without causing the tube erosion associated

with soot blowers. The benefit of this is that on average the boiler maintains more cleanliness and therefore

operates more efficiently. Soot blowers typically clean 2-3 times a day and between those cleanings, the

tubes become fouled again leading heat transfer efficiencies to continue to degrade until the next soot

blower cycle. Impulse cleaners typically operate multiple times per hour throughout the day and therefore

maintain higher heat transfer efficiencies.

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Impulse cleaners have been applied by plants in boilers to reduce their reliance on soot blowers and slow

down the associated tube erosion, augment the cleaning of deposits to gain back efficiency loss, and to

completely replace existing soot blowers that are not performing to plant expectations. Impulse cleaners

are generally not utilized for cleaning of filter bags in baghouses, or catalyst in SCR reactors, however there

are other applications where friable deposits clinging to heavy metal structures can be removed with

impulse waves.

Placement and Operation of Impulse CleanersSince most impulse cleaners are wall mounted units that

emit shockwaves radially out from the penetration point,

it is necessary to design the placement of the system

or systems and operate them in such a manner to fully

cover the area to be cleaned. This section will describe

the basic operation of impulse cleaners and how this

impacts cleaning sequence and range of the cleaning

impulse wave.

Impulse waves from each cleaner are created

individually, in that each combustion event results in a single impulse wave. Impulse cleaners therefore

operate in cyclic cleaning sequences, creating multiple cleaning waves per cleaning sequence. Typical

cleaning sequences consist of 10-20 impulses with delays of 30 minutes to two hours between cleanings,

radically different from the typical operation of a soot blower cleaning system. This exemplifies a pro-active

cleaning cycle that enables continued removal of deposits resulting in improved average efficiency of the

Placement of the cleaners isimportant to the success of

installation and it is important totake into account tenacity of

deposit, its physical state, andthe temperature of the flue gas

through which the shockwave is travelling.

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boiler. This is possible due to the low operation cost of the cleaner and the fact that it does not damage

tube surfaces.

Each impulse is the result of the filling of the generating chamber with a mixture of fuel and compressed air

and igniting that mixture instantaneously. The combustion event moves at speeds approaching 1800 m/s

(roughly five times the speed of sound) as it consumes the fuel/air mixture. This supersonic

combustion speed is what creates the strong shock wave coupled to the leading edge of the combustion

flame as it consumes the volume gas within the chamber. The generating chamber shape can affect the

strength of the resulting shock wave significantly. Once the fuel and air is fully consumed, the shockwave

decouples from the combustion process, exits the chamber, and begins expanding spherically as it

continues to travel away from the penetration point of the cleaner. A unique benefit of cleaning with

impulse waves versus soot blowers is that the impulse waves will actually clean the leading edge and

trailing edge of all tube-scale structures it passes. This is what allows the impulse wave to penetrate deeply

throughout tube bundles and clean in a non-line-of-site manner to remove deposits typically left behind by

other cleaning systems. This is a very important feature of an impulse wave with regards to boiler cleaning,

where deposits build up in many areas that soot blowers cannot reach.

Although the Mach 5 velocity of the impulse wave quickly decays to the speed of sound once it leaves the

combustion chamber, the steep pressure rise associated with the wave decays significantly slower as the

impulse wave expands and travels throughout the boiler. This pressure decay is approximated by blast wave

decay theory and has been verified via previous research (Glaser, 2007). Based on what is known about

leaning with pressure waves, once the wave pressure decreases beyond a threshold, dependent on type

of deposit, it is no longer effective at removing those deposits. Similar to how the further away the deposit

is from a soot blower jet, the less effective that jet of air/steam is for cleaning. Therefore, the initial shock

strength is a variable that can affect the effective cleaning distance of each cleaner. Placement of the

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cleaners is important to the success of installation, and it is important to take into account tenacity of

deposit, its physical state, and the temperature of the flue gas through which the shock wave is traveling.

The more tenacious, or more aggressively attached that the deposit is to the heat transfer surface, the

higher the pressure threshold required to remove it. Physical state is important, because as deposits cool,

they move from a molten state, to a plastic state, and eventually to a solid state. In a molten state, the

deposits absorb acoustic energy without breaking apart. Another important consideration is gas

temperature in the area of the boiler through which the impulse waves are traveling. As gas temperature

increases, the density of that gas decreases. Pressure waves moving through less dense gas result in

smaller pressure rise and therefore less cleaning range. Taking all of these variables into consideration,

impulse cleaning technology has been successfully implemented for coal-fired boilers throughout the entire

convection passes, up to temperatures as high as 1650 Fahrenheit.

Various fuel and oxidizer combination requirements exist for impulse cleaning systems. Physical sizes of the

combustion chambers can vary greatly based on the fuel/oxidizer combination. Operation costs vary based

on many factors, but a typical impulse cleaner can cost $2,000.00 USD to $4,000.00 in yearly operation

costs. Most installations have less than a one-year payback.

When impulse cleaners were first introduced to market, they were initially sought after to improve difficult

buildup situations in existing boilers where changes in fuel, operating conditions, or degradation of existing

cleaning systems had caused serious issues in the efficient operation of convection passes. Now, the

industry is seeing emergence of sites interested in replacing entire (traditional) cleaning systems with

impulse cleaning due to the operational and financial benefits.

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ConclusionIn the last five years there have been many advances in impulse cleaning systems and they have become

more accepted by utility and industrial boiler operators. Placement and operation of the systems is crucial

to their performance. When applied correctly, impulse cleaning systems represent a rapid change in boiler

cleaning technology and have provided proven benefits that include more effective non-erosive heat

transfer surface cleaning, lower operation and maintenance cost, and lower installation costs.

NotePaper presented by GE at Coal-Gen Europe 2011.

Works CitedGlaser, A. J. (2007). Performance and Environmental Impact Assessment of Pulse Detonation Based Engine

Systems. Cincinnati, OH: University of Cincinnati.

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Q: How is an impulse wave different from a typical sound wave used in acoustic cleaning?A: Acoustic waves have hundreds of pressure peaks per second. Impulse waves are more intense with fewer pressure peaks per second. That means the impulse waves can achieve greater cleaning power for tenacious deposits and can penetrate deeper into tube bundles.

Q: Will it damage my boiler?A: The Powerwave+ Impulse Cleaning System will not damage your boiler as other cleaning methods can. The impulse cleaning technologys shock wave generates a pressure disturbance in the gas stream, which causes displacement of dust particleswithout exposing the boiler tubes to erosion from steam soot blowing.

Q: What fuel is used?A: The system uses ethylene gas, a light hydrocarbon C2H4, which is readily available through local gasdistributors. Each system can generate about 10,000 impulses from a single, 30 lb. tank of ethylene.

Q: What else is required to install a Powerwave+ Impulse Cleaning System?A: In addition to ethylene gas, electrical power and plant air are needed. A standard 110/220 VAC line isrequired to power the control system. And the system draws about 80-100 SCFM at 80-90 psi when operating.

Q: How do I know if the technology is right for my application?A: Powerwave+ impulse cleaning is best suited for dry friable deposits. Systems have delivered effective results in superheaters down to economizers on boilers burning PRB coal, known for pluggage due to high ash content. Systems have been effective for both staggered and inline tubes, finned and smooth tubes, and tubular airhearters.

Q: How many systems are required to clean a boiler?A: This varies, but GEs engineering team can quickly determine the appropriate locations and number ofsystems needed for a boiler based on drawings and basic operational information.

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Powerwave+ Impulse Cleaning SystemFor more information, contact us at:1-800-821-22221-816-356-8400or visitwww.ge-energy.com/powerwaveplus

is GEs commitment to imagine and build innovative solutions to todays environmental challenges while driving economic growth. An ecomagination product must demonstrate a significant and measurable improvement to its customers operating performance or value proposition and environmental performance.

2012 General Electric Company. All rights reserved. GEA30396e (10/2012)

www.ge-energy.com/powerwaveplus

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