combustion of # 2 oil with chrorides

[mukundjoshi]

hi there,

anybody has experience of combustion of # 2 fuel oil with Chlorides (50 ppm).
we want to use this fuel in water tube boiler. tubes are plain carbon steel.
Chorides will combine with moisture to form HCl - this would happen when flue gases reach below dew point, but what would happen in the combustion chamber at high temperature (from 800 to 1800F)?
any experience, suggestions ?
regards,

 

[niko99]

I should preface my remarks by stating that the bulk of my experience has been in coal and MSW combustion.

The fuel will introduce chlorine-containing compounds, as well as alkali metal compounds [especially sodium (Na) and potassium (K)], and heavy metals such as lead (Pb), tin (Sn), and zinc (Zn), all of which may combine in the flame to form potential corrodants. Many of these chloride compounds have melting points under 600 °F, and some are as low as 350 °F. Low-melting point chlorides of these metals or mixtures of chlorides, deposited on the heat transfer surfaces, removes the protective oxide scale from the tube surfaces, allowing for rapid dissolution into the molten salts, or rapid oxidation of the tube surface. Solid chloride deposits also can cause corrosion in the presence of sulfur dioxide in the combustion gas. Although sulfates form in the deposits on the tube surfaces, they typically have melting points above the temperatures that are typically encountered on the heat transfer surfaces of boilers, and so are not particularly corrosive. Corrosion occurs on furnace walls where metal temperatures are in excess of 450 °F, under constant or cycling (redox) reducing conditions. These surfaces also are vulnerable to corrosion when in contact with combustion gases at temperatures in excess of 1750 °F.