Ash fouling monitoring based on acoustic pyrometry in boiler furnaces

• An approach to monitor ash fouling on the heat surface in boiler furnaces was developed.
• The paper provides acoustic technology to obtain the changes of flue gas temperature near the water-cooling wall.
• The sound rays close to the water-cooling wall bend toward the high temperature area inside the furnace.
• A new clean factor, &, was proposed based on acoustic pyrometry.
• The technique is applied to a domestic 600-MW coal-fired boiler.

Unexpected fouling of heat transfer surfaces has always been one of the main operational concerns in coal-fired utility boilers. A cost-effective way to address this difficulty is the continuous monitoring of fouling tendencies. This article has adopted acoustic pyrometry to monitor the changes of the flue gas temperature near the heat surface and has proposed a new clean factor, &, based on this acoustic method to monitor the ash fouling. A laboratory study and field research using a boiler were conducted. The results indicated that the acoustic system could be adopted to monitor temperature changes near the water-cooling wall in the boiler furnace. The new clean factor, &, could be used to monitor the changes of the ash fouling on the heat surface. This study may help to develop a more intelligent use of soot blowers, save power station boiler furnace energy and reduce discharge.