Boiler Chemicals

                                      Evaporation in a boiler causes impurities to concentrate. Boiler scale results from water impurities precipitating out on heat transfer surfaces or by suspended matters (such as organics) settling out on the metal and becoming hard and adherent. The high temperature in a boiler system breakdown some minerals, causing others to become less soluble.  

             Generally, as water in contact with hot metal surfaces evaporates, the dissolved solids in the water tend to deposit out. Impurities in water, which results in scaling and deposition, includes dissolved bicarbonates of calcium and magnesium (both are termed as hardness in boiler feed water which is generally associated with low pressure system), minerals such as silica, suspended or dissolved iron, oil and other process contaminants.Silica, usually not present in large quantities in water, can under certain conditions form an exceedingly hard scale. 

                             Oil and other process contaminants can form deposits as well as promote deposition of other impurities. Iron and copper from returning condensate, formed due to corrosion, can also cause potential deposition in the system.

Corrosion is the process whereby the boiler metal reverts to its ore form.  Iron, for example, reverts to iron oxide as a result of corrosion. Corrosion in a boiler system is attributed to one or a combination of the following causes. 

Oxygen in the boiler feed water reduces the boiler metal iron to its oxides form. This involves an oxidation - reduction reaction. High temperature and the presence of carbon dioxide accelerate this corrosion reaction, which is characterized by pitting. Concentrated solids at a higher heat input area in a boiler system can also produce corrosion in boiler. Process side contaminants such as hydrogen sulphite, ammonia or sulfur bearing gases may increase attack on copper alloys in the system. Organics such as sugar or solvent, if present in boiler water can decompose to release corrosive organic and mineral salts.  

Corrosion in the boiler system can be of two forms: general and pitting.  General corrosion involves a loss of metal uniformly over a large surface area, leading to boiler metal thinning.Pitting corrosion, a more severe form, involves metal loss over a localized area leading to metal perforation in a short period to time.

Corrosion is the process whereby the boiler metal reverts to its ore form.  Iron, for example, reverts to iron oxide as a result of corrosion. Corrosion in a boiler system is attributed to one or a combination of the following causes. 

Oxygen in the boiler feed water reduces the boiler metal iron to its oxides form. This involves an oxidation - reduction reaction. High temperature and the presence of carbon dioxide accelerate this corrosion reaction, which is characterized by pitting. Concentrated solids at a higher heat input area in a boiler system can also produce corrosion in boiler. Process side contaminants such as hydrogen sulphite, ammonia or sulfur bearing gases may increase attack on copper alloys in the system. Organics such as sugar or solvent, if present in boiler water can decompose to release corrosive organic and mineral salts.  

Corrosion in the boiler system can be of two forms: general and pitting.  General corrosion involves a loss of metal uniformly over a large surface area, leading to boiler metal thinning. Pitting corrosion, a more severe form, involves metal loss over a localized area leading to metal perforation in a short period to time.