A friend involved in industrial cleaning recently tried to explain to me how ash can build up and become really difficult to remove. The analogy he used made me smile - 'pigeon poo cleaning'!
He explained that ash builds up constantly in things such as power plant economizers and that it gets baked on with the high temperature, forming a hard crud. He asked me which was easier - cleaning up pigeon poo the moment it's been dropped onto a ledge or waiting for a few hours until it's been left to dry and harden? The answer was obvious :)
So the ideal way of dealing with ash build up in an economizer, he explained, would be to prevent it occurring in the first place and not allow it to form a hard deposit. This is where the sonic soot blower is a great tool apparently as it emits audiosonic waves at regular intervals and prevents ash build-up. By contrast a steam soot blower tends to be employed at intervals of about 8 hours, so the ash can build up in that 8 hours and become baked on hard. This can result in the steam soot blower not being able to remove it fully and thus performing with reduced efficiency.
I never thought pigeons could be used to explain engineering science but there you are!
