The steam boiler built in 1991 is one of the most important units at the Alter Galgen site. The steam boiler supplies thermal energy in the form of saturated steam. This steam (temperatures up to 196 degrees Celsius) is used to supply heat to the heating chambers and the production boilers. Ursa-Chemie has now decided, after consulting with the Schweitzer company, to carry out a professional chemical cleaning of the water side of the steam boiler to remove boiler and water scale.
A view into the interior of the steam boiler shows the flame tubes with a thin white layer of scale deposits.
The formation of deposits in water-bearing systems such as in the steam boiler leads to a reduction in heat transfer, as scale deposits have very poor thermal conductivity – energy consumption increases and performance falls. In addition to increased energy costs, thicker stone coverings experience thermal stresses because the coefficient of thermal expansion of the stone covering is much lower than that of the underlying metallic material. This can cause cracks to form (especially common in steam boilers), resulting in expensive repairs. To remove lime deposits, acids containing special corrosion inhibitors are used. The purpose of these corrosion inhibitors is to protect the metallic materials from acid attack. A monomolecular protective film is selectively formed on the metal surface without hindering the dissolution of the coating by the acids. Depending on the metal present in the system or the composition of the coating, an appropriately adapted stone removal agent must be used. Company Schweitzer has the already optimally adjusted combination products of acid and anti-corrosion agent, so that it could carry out the chemical rehabilitation of the water space of the steam boiler.