CLEANINGCLEANING

Cleaning
We offer a mechanical hammer cleaning system, "Ahlstrom-Foster Wheeler (Finland)" type, already installed in the above mentioned plants. Advantages derived from the use of this type of percussion system are as follows:
- same hammers for all heat exchangers,
- hammers and driving systems are totally outside the flue gas zone, so as to avoid hot corrosion effects, which are induced for skin temperatures above 400 °C,
- hammers can be removed at the same time as heat exchangers and can be immediately installed on the spare heat exchange units.

Over 4000 applications of this kind of hammers have been carried out in about 500 plants

The system is managed by a PLC, allowing to vary cleaning times and intervals between cleaning sessions, while a device inside the hammers allows to change their percussion effort. Each hammer has start/stop and manual/automatic push buttons.

Extraordinary cleaning, when the plant comes to a halt, can be carried out without operators having to enter the flue gas zone. It is done through portholes at different heights with compressed air or washing jets for the radiant zone. For the convective zone it is done from numerous portholes, placed among the heat exchange units with compressed air or mechanically. This latter operation can be carried out for coldest heat exchangers (economizers), also when the boiler is in operation .

In order to facilitate quick and economical cleaning or maintenance of the radiant chambers, they are prepared for fitting partial scaffoldings, without having to start from the bottom part of the chambers themselves.

For manual maintenance during plant stop, as an alternative or in addition to the portholes, the radiant zone can be accessed inside with an ascending system, using a hoist let down from the chamber roof.

We advise against steam soot-blower cleaning in this type of plant, because it can do more damage than surface cleaning. In fact the risk of corrosion due to the reaction between steam and tube dust increases considerably; localised erosion is also possible where steam jets hit the tube and cleaning is limited to some zones only.