DUŠKA Jaroslav U.S.Steel Košice, s.r.o.

Spoluautoři DROTÁR Atila, MERC Jaroslav, MAŠLEJOVÁ Alica

This contribution deals with the occurrence of copper and copper oxides in the Heating Plant heat-transfer circuit, particularly in the steam-water system of high pressure steam boilers. Boilers produce high-pressure superheated steam, which is used for cogeneration of heat and electricity. Steam-water boiler system consists of a set of steel tubes, chambers, drum and accessories made of Class 12 and 15 materials. Materials containing copper do not occur in the boiler system. The presence of copper in the heat transfer medium (condensate, water, steam) is undesirable, is monitored and evaluated by chemical analyses. Boilers as steam sources are connected to the consuming units - turbo-generators, where the steam is used to produce electricity or steam with lower pressure levels. The system of turbo-generators contains brass materials, which are used in condenser tubes and regeneration heaters. Initial symptoms of excessive amounts of copper in the boiler circuit revealed themselves by plugging the blowdown system from boiler drums. Subsequent research and analyses have shown the sources and mechanisms of clogging of the boiler systems with copper and copper oxides and also pointed to the significant risks of deposition of copper particles on the inner surface of steel tubes, because each particle creates an electric cell and causes galvanic pitting corrosion of boiler tubes. Analyses of the systems and sampled boiler tubes confirmed pitting corrosion in a more or less extensive stage.