Why are there number soot blower units in large blower?

Why are there number soot blower units in large blower? Correct Answer To clean adequately

Steam jets clean soot from heating surface in their proximity, but the action is limited in extent in a close array such as tube banks; hence several units may be needed to clean the boiler adequately. It is quite common to see 8 to 16 units in a large boiler.

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