SONIC HORN TO IMPROVE BOILER EFFICIENCY

Sonic Soot Blowers in Boilers Vs Steam Soot Blowers

Soot is an excellent insulator and reduces heat transfer in the boiler heat transfer area thereby
stack/chimney flue gas temperature goes higher than normal which is a waste of energy.

When SO2 from the flue gas reacts with alkali ash, components forms alkali sulphates which act
as a glue and fly ash particles bind together. This type of deposit happens in convective
surfaces such as convective superheaters, boiler banks, evaporators, economizers, air
preheaters, etc. in coal-fired boilers.

Ash deposits/soot deposits need to be removed continuously through a steam soot blower or
through sonic horns to avoid wastage of energy due to higher stack temperature/dry flue gas
loss.

Steam soot blowers are traditional soot blowers which have various disadvantages such as
those mentioned below:

● Operation cost is too high
● The initial investment is too high
● To drain condensate properly before operation, a steam trap management program is
needed so that dry steam is allowed to pass through the steam soot blower to avoid
erosion of boiler tubes
● Steam soot blowers require frequent maintenance or it may damage boiler tubes
Sonic horn is an alternative to a steam soot blower with various advantages as mentioned
below:
● Sonic horn does not create corrosion, erosion or mechanical damage to boiler tubes and
does not produce any effluent
● Sonic horn/Sonic soot blowers usually make noises for a few seconds (200DB) every 10
to 15 minutes and can be operated by SCADA or individual timer on each solenoid valve
hence, the air requirement for producing sound is too low which is a 2mm hole at 6
Kg/CM2 1 Min in one hour hence operating cost is far less than steam soot blowers. It
creates sound on the same principle as Sankha
● No moving parts in the sonic horn hence the meager maintenance cost
● 360° cleaning of all tube surfaces is possible in sonic horn
● Help to combat global climate change and the effects of global warming
● The cost of one sonic horn is around Rs. 1 Lakh and the steam soot blower is Rs. 5 lakh
hence initial investment is very low
● One steam soot blower if operated 3 times in a day consumes 3MT steam which is
equivalent to 500 kWh whereas one sonic horn consumes 2 kWh equivalent of power in
a day hence operating cost is very low
● The maintenance cost of one sonic horn is Rs. 7000 per year (diaphragm) whereas the
maintenance cost of one steam soot blower is Rs. 1 lakh to 3 lakh
● Both soot blowers can reduce stack temperature by 20°c thereby improving 1%
efficiency but steam soot blower requires much dedication and effort resulting in people
not operating it even if it is installed whereas sonic soot blower operates in auto mode. 5
tph steam improvement that totals(A B C D E) which is equal to 36000 MT steam
improvement in a year. For 300 days running in a year, we will have 6.3 crore worth of
additional power generation at a power cost of Rs 7 per unit

If we replace all steam soot blowers of economizers of WHRB ABCDE 18 Nos with 24 sonic horns, then saving are as mentioned in the table below:

Remarks:

It is pertinent to note that the steam soot blower is hardly operated in a plant so the savings of Rs 6.3 crores as per point no 4 is compromised whereas the sonic horn operates in auto mode thereby fetching the benefit of Rs 6.3 crores directly to the company and additional 2 croresl benefits compared to steam soot blower.

Conclusion:

The above calculation is made for the economizer of WHRBS (waste heat recovery boilers) however, it is advisable to install evaporators as well as all pressure parts of coal-fired boilers to maximise benefits. It is also installed in the air preheater as well as ESP to improve hot air temperature to increase efficiency and to get rid of the perennial problem of the RAPPING SYSTEM to fulfil compliances as per the GPCB norms. Initially, we may go for economizer which is low-hanging fruit. We may go for other pressure parts and heat exchangers like APH in a phased manner.

Author

Ashwini Mishra

V.P- CPP