For a long, there is a big challenge in Power, Cement, Mineral and ore processing plant operation with clogging of Silos and Bunkers, scaling on Heat Exchanger/Boiler/ ESP and many other places. It will bring the risk of emergency shut down together with lose of efficiency of the total system. Due to frequent shut down for long hours, a considerable amount of revenue is lost on regular basis. In addition to the above, in a number of cases in the past, valuable lives have been lost during the manual cleaning operation.
The above challenge has necessitated the scientists to innovate some technology which could bring an end to those age-old traditional cleaning process. All scientists in this field were working on this and a few years back brought Pneumatic Hammer technology. This technology was definitely improved the efficiency of cleaning of silos using Pneumatic hammer instead of manually hammering, but it takes long time, high cost and brings the risk of damaging the mother plate of the Silos prematurely.
A solution provider company from China, started working on this challenge at their Laboratory and did a number of experiment .They thought if they use different sound frequencies and can generate resonance, the same could create a surge frequency on the material that is sticking inside the Silo wall. This surge frequency due to resonance can help to dislodge the clogged material from the silo surface to make the surface clean. By using compressed air, a multi-frequency generating device was made. Frequency controllers were also used to regulate the frequency as per requirement. This Audio cleaning system was retrofitted in one of the Silos of a cement plant in China to test its efficiency of cleaning. The result was highly encouraging. It is cleaning the surface to almost 100 percent at ease without consuming much energy or effort.
Material is vibrated in resonance with certain frequency of sound wave. Resonance is generated on to the material particles helps to dislodge the clogged material from the surface of the silo. Since the material is getting loosen, it would lose its sticking ability with the silo surface. Material hence would flow smoothly, sufficiently without clogging the silo.
Audio cleaning and clogging Removal Technique
It is to pass compressed air through the audio sound generating device. The audio resonance cavity to produce a strong audio wave and then amplify the audio sound wave by the audio amplifier, into the application area. Sound wave propagates in flue, furnace and silo which affects the synchronous vibration of ash particles in air or in flue gas.
Under the action of sound wave vibration and repeated accumulation, it is difficult for small particles to approach the ash exposed surface. High efficiency acoustic wave can also destroy and peel off the dust deposited on the heating surface, so as to achieve the purpose of clogging removal.
This Audio technology is much better, convenient and highly economical if compared with lastly introduced Pneumatic hammering one. It does not require any human interference. This technique has the following advantages:
Simple operation, cleaning Silo at any time on real time basis, no need to stop the production. Hence no production loss due to intermittent cleaning operation.
Compared with manual cleaning, the efficiency of silo cleaning has been greatly improved and cleans the silo wall more thoroughly(may be up to 100 percent).
Unmanned real time cleaning of silo wall is realized.
Reducing the security risk of personnel who would be cleaning at the lowest .
level to ZERO. The casualties that otherwise arise in the process of silo cleaning will be totally eliminated.
Since it requires Compressor with working pressure of 0.25 to 0.3 MPa. The energy requirement is very low.
Since it does not call for any shut down, the efficiency of the total system achievable is very high.
Emission of dust is in Audio system is reduced
It ensures the continuity of safety in continuously running plant.
Audio cleaning has got a wide coverage - A single unit can cover 12 square meters high .
It develops a strong energy- the audio propagates.
in the range of 25 to 360 Hz randomly by vibration.
Very low energy consumption - A single unit consumes 0.15cubic meter per minute while working pressure is 0.25 to 0.3 MPa.
Very long service life - the service life of main body of the equipment is more than 10 years.
No new Silo is required for fitting the Audio unit- Retrofitting is possible .Hence no additional cost is involved in installing this system in existing System.
No maintenance is required to run the Audio cleaning system continuously.
Cost is very low - it is less costly.
Life Guarantee - A minimum Guarantee of 10 years is possible from the manufacturers.
Initially a prototype was retrofitted in a cement silo in one of the plants in China. After getting a positive feedback from them, the system was offered to other Thermal power Plants, Coal plants, Chemical plants situated in different parts of China. Each user got positive results by implementing this system in their equipment. With this, at present more than 40 companies in China are using this innovative technology of cleaning the Silos etc. in their respective plants.
Feedback from the Prototype user.
Feedback from all the prototype users are very encouraging. Since this requires very less investment in retrofitting the equipment, together with very little energy consumption on sustained basis, implementing this innovative technology in their individual plants were very easy.
Conclusion: It will bring a lot of benefit if this Audio cleaning in implemented in all Thermal Power, Cement, Mineral Processing plants in India. It would be ideal solution in all cement plants located in all over India.
To be given box
Typical applications area
Smoke Chamber Silo Waste Heat Boiler Calciner
Shrinkage of blanking pipe
Authored by: U K Mullick, who is a Mechanical Engr, worked at L&T,WIRTGEN INDIA,TELCO, AMW MOTORS (ESSAR Group), Mahindra & Mahindra. A total of 40 years of experience in Sales, Marketing and Business Development.