[vc_row][vc_column][vc_custom_heading text=\”Ineffective Chemical Cleaning?\” use_theme_fonts=\”yes\”][vc_custom_heading text=\”Introduction\” font_container=\”tag:h3|text_align:left\” use_theme_fonts=\”yes\”][vc_column_text]
Ineffective chemical cleaning? Not really… we have encountered situations where engineers and operators complaint about the cleanliness of the boiler as they see a black liquid coming off the blowdown system during first fire.
It´s not difficult to get carried away by a first impression and put into question the effectiveness of the chemical cleaning.
[/vc_column_text][vc_custom_heading text=\”Explanations\” font_container=\”tag:h3|text_align:left\” use_theme_fonts=\”yes\”][vc_column_text]
This dark watery constituent is in reality a very welcome natural corrosion-protection product called Magnetite and it is formed as the steel surface is exposed to water under certain conditions.
The formation of Magnetite is an electrochemical process controlled by a continuous diffusion of iron ions from the steel surface across the water boundary layer and its stability, morphology and porosity depends on the oxidation-reduction potential, pH, oxygen concentration, pressure, temperature and the influence of the make-up water chemistry (CO2, Cl, Si, Na, Ca, Mg…)
Solubility rises with temperature up to 150ºC, then decreases with a steep drop to 300°C. Pressure promotes the growth of magnetite and thickness Having said that, the reason of the dark appearance of the blowdown during a boiler ramp-up is mainly due to the deposition of low quality magnetite since steady conditions has not been reached yet.
[/vc_column_text][vc_single_image image=\”11931\” img_size=\”full\”][/vc_column][/vc_row]
