Sonic soot blowers
Encyclopedia
Sonic soot blowers offer a cost-effective and non-destructive means of preventing ash
and particulate
build-up within the power generation industry. They use high energy – low frequency sound waves that provide 360° particulate de-bonding and at a speed in excess of 344 metres per second. Because they employ non-destructive sound waves, unlike steam soot blower
s they eliminate any concerns over corrosion
, erosion
or mechanical damage and do not produce an effluent stream.
such as an oboe
, where the ‘base tone’ is created by blowing air over a reed and then converting this ‘base tone’ into a particular high or low note, depending on how far the sound wave has to travel along inside the body of the instrument.
The sonic soot blower operates in the same manner, the ‘base tone’ being produced by passing compressed air
into a wave generator which houses a titanium
diaphragm causing it to oscillate rapidly. This ‘base tone’ is then converted into a range of selected frequencies ranging from 350 Hz down to 60 Hz by the design and length of the horn section
, producing the desired sound frequency at a sound level approaching 200 dB. The sonic soot blower is usually ‘sounded’ for a few seconds at intervals of between 3 and 10 minutes. This ‘sounding’ pattern is normally controlled via the plant’s PLC. However, it may also be operated by such means as a SCADA
system, individual timers on each solenoid valve
or via a manual ball valve
.
as opposed to some sonic horns which are manufactured from heavy cast iron
. For installations in harsher environments, such as high temperature or acidic gas streams, other types of stainless steels are used such as 310, 316 and 825.
surface to which they are bonded and so carried away in the gas stream. This prevents the ash from building up and sintering
onto the boiler
tubes thus significantly reducing thermal efficiency
. This is in contrast to the operating principles of steam soot blowers which are usually only employed at most once every eight hours by which time the ash has built up and baked hard onto the heat transfer surfaces. The steam soot blower then tries to blast away his hard deposit, usually only from the leading edge of the steam tubes.
s and other waste fuels including biofuels
. Depending on the application and boiler plant design, sonic soot blowers usually totally replace existing high maintenance steam soot blowers whether of the retractable or rotary type. In a few cases, sonic soot blowers can be used to supplement steam soot blowers.
Sonic soot blower cleaning technologies can be applied in superheaters
, generating sections, economizers
, and airheaters as well as downstream equipment such as electrostatic precipitators
, baghouse filters and fans.
The main advantages of sonic soot blowers over steam soot blowers
are:-
• Elimination of opacity spikes due to more regular, more efficient cleaning
• No structural damage to tube bundles or boiler structure
• Elimination of tube corrosion and erosion problems
• 360° cleaning of all tube surfaces – not harsh leading edge tube cleaning as with steam soot blowers
• Prevention of ash build up and sintering on steam tubes due to sonic soot blowers regular operation
• Extremely low maintenance or operational costs
• Eco-friendly – helps to combat global climate change
and the effect of global warming
Incinerator bottom ash
Incinerator bottom ash is a form of ash produced in incineration facilities. This material is discharged from the moving grate of municipal solid waste incinerators. Following combustion the ash typically has a small amount of ferrous metals contained within it. This ash can be processed to...
and particulate
Particulates
Particulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...
build-up within the power generation industry. They use high energy – low frequency sound waves that provide 360° particulate de-bonding and at a speed in excess of 344 metres per second. Because they employ non-destructive sound waves, unlike steam soot blower
Soot blower
A Sootblower is a system for removing the soot that is deposited on the furnace tubes of a boiler during combustion. Various types of soot blowers such as Wall Blowers, Long Retractable Blowers and Air Heater Blowers are used for the cleaning...
s they eliminate any concerns over corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
, erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
or mechanical damage and do not produce an effluent stream.
History and Design
The sonic soot blower can in some ways be compared to a musical reed instrumentReed (instrument)
A reed is a thin strip of material which vibrates to produce a sound on a musical instrument. The reeds of most Woodwind instruments are made from Arundo donax or synthetic material; tuned reeds are made of metal or synthetics.-Single reeds:Single reeds are used on the mouthpieces of clarinets...
such as an oboe
Oboe
The oboe is a double reed musical instrument of the woodwind family. In English, prior to 1770, the instrument was called "hautbois" , "hoboy", or "French hoboy". The spelling "oboe" was adopted into English ca...
, where the ‘base tone’ is created by blowing air over a reed and then converting this ‘base tone’ into a particular high or low note, depending on how far the sound wave has to travel along inside the body of the instrument.
The sonic soot blower operates in the same manner, the ‘base tone’ being produced by passing compressed air
Compressed air
Compressed air is air which is kept under a certain pressure, usually greater than that of the atmosphere. In Europe, 10 percent of all electricity used by industry is used to produce compressed air, amounting to 80 terawatt hours consumption per year....
into a wave generator which houses a titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
diaphragm causing it to oscillate rapidly. This ‘base tone’ is then converted into a range of selected frequencies ranging from 350 Hz down to 60 Hz by the design and length of the horn section
Horn section
In music, a horn section can refer to several groups of musicians. It can refer to the musicians in a symphony orchestra who play the horn . In a British-style brass band it refers to the tenor horn players. In popular music, it can also refer to a small group of wind instrumentalists who augment a...
, producing the desired sound frequency at a sound level approaching 200 dB. The sonic soot blower is usually ‘sounded’ for a few seconds at intervals of between 3 and 10 minutes. This ‘sounding’ pattern is normally controlled via the plant’s PLC. However, it may also be operated by such means as a SCADA
SCADA
SCADA generally refers to industrial control systems : computer systems that monitor and control industrial, infrastructure, or facility-based processes, as described below:...
system, individual timers on each solenoid valve
Solenoid valve
A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid: in the case of a two-port valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports...
or via a manual ball valve
Ball valve
A ball valve is a valve with a spherical disc, the part of the valve which controls the flow through it. The sphere has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends...
.
Construction
Sonic soot blowers are normally constructed from fabricated, 316 grade stainless steelStainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
as opposed to some sonic horns which are manufactured from heavy cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...
. For installations in harsher environments, such as high temperature or acidic gas streams, other types of stainless steels are used such as 310, 316 and 825.
Performance
Sonic soot blowers create a rapid series of very powerful sound induced pressure fluctuations which when transmitted into the ash or particulate, cause them to de-bond from other particles and from the heat transferHeat transfer
Heat transfer is a discipline of thermal engineering that concerns the exchange of thermal energy from one physical system to another. Heat transfer is classified into various mechanisms, such as heat conduction, convection, thermal radiation, and phase-change transfer...
surface to which they are bonded and so carried away in the gas stream. This prevents the ash from building up and sintering
Sintering
Sintering is a method used to create objects from powders. It is based on atomic diffusion. Diffusion occurs in any material above absolute zero, but it occurs much faster at higher temperatures. In most sintering processes, the powdered material is held in a mold and then heated to a temperature...
onto the boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
tubes thus significantly reducing thermal efficiency
Thermal efficiency
In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator for example.-Overview:...
. This is in contrast to the operating principles of steam soot blowers which are usually only employed at most once every eight hours by which time the ash has built up and baked hard onto the heat transfer surfaces. The steam soot blower then tries to blast away his hard deposit, usually only from the leading edge of the steam tubes.
Advantages
Sonic soot blowers are a proven alternative to conventional steam soot blowers in power generation plants which burn a range of fossil fuelFossil fuel
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...
s and other waste fuels including biofuels
Biofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
. Depending on the application and boiler plant design, sonic soot blowers usually totally replace existing high maintenance steam soot blowers whether of the retractable or rotary type. In a few cases, sonic soot blowers can be used to supplement steam soot blowers.
Sonic soot blower cleaning technologies can be applied in superheaters
Superheater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...
, generating sections, economizers
Economizer
Economizers , or economisers , are mechanical devices intended to reduce energy consumption, or to perform another useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, powerplant, and heating, ventilating, and air-conditioning uses are...
, and airheaters as well as downstream equipment such as electrostatic precipitators
Electrostatic precipitator
An electrostatic precipitator , or electrostatic air cleaner is a particulate collection device that removes particles from a flowing gas using the force of an induced electrostatic charge...
, baghouse filters and fans.
The main advantages of sonic soot blowers over steam soot blowers
Soot blower
A Sootblower is a system for removing the soot that is deposited on the furnace tubes of a boiler during combustion. Various types of soot blowers such as Wall Blowers, Long Retractable Blowers and Air Heater Blowers are used for the cleaning...
are:-
• Elimination of opacity spikes due to more regular, more efficient cleaning
• No structural damage to tube bundles or boiler structure
• Elimination of tube corrosion and erosion problems
• 360° cleaning of all tube surfaces – not harsh leading edge tube cleaning as with steam soot blowers
• Prevention of ash build up and sintering on steam tubes due to sonic soot blowers regular operation
• Extremely low maintenance or operational costs
• Eco-friendly – helps to combat global climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
and the effect of global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...