Role of Chemical Compounds in Boiler Maintenance

Boilers and their assembly of system should be well maintained in order to keep them moving efficiently and to prolong their lifespan. People die from accidents every year resulting from a poorly maintained water treatment system. It is even said that a typical 30-gallon home water boiler has enough energy to throw a 2,000 pound car up a hundred feet in the air if the system disastrously fails. Some companies tend to be delinquent with maintenance and approach the issue reactively. Evaluation and repairs are only made when a failure is seen in the system. In effect, expenses are raised, especially with labor and overtime. Anticipating and remedying problems proactively before conditions aggravate are the best approaches to save lives and expenditures. Part of these approaches is through the application of boiler  chemicals. Boiler chemicals are composed of different compounds, depending on the boiler type, that are applied regularly to keep system in top shape. Some of them are blended in different formulations, but some are composed only of one specific type to cater to a specific need.

Alkalis are used to boost boiler water pH to 10.5. An alkali will ensure the reduction of corrosion rate, maintain a 3:1 ratio of total alkalinity to silica to avoid boiler plating, and allow polymer to react with calcium.

Amines are used to boost the condensate pH range to 7.8-8.7, reducing the overall steam system corrosion rates. When steam is generated, carbonic acid forms, which will render the steam acidic. A low pH will result in excessive condensate pipe corrosion. Amines are volatile and increase the condensate pH immediately when it is introduced into the steam header or boiler water.

Phosphates and polymers are used to keep calcium in solution and keep scale from developing. Phosphate treatment must be done daily to release accumulated calcium. Failure to do so will cause build-up, which in turn will lead to scaling. This will decrease boiler efficiency and will drastically increase your fuel cost. After introduction of the compound to the boiler water, polymer attaches itself to the calcium ions to be able to exit the system either through the surface or the bottom blowdown.

Sulfites are used to remove oxygen, another cause of corrosion. Dissolved oxygen enters boiler either in make-up water or as sucked air into the system. It is extremely corrosive to the tubes, and build-up will form localized pits, resulting in premature tube failure in the long run. A sulfite residual of 20 to 40 ppm. must be maintained in your boiler system.

References:
Ezine - http://ezinearticles.com/?The-Purpose-of-Boiler-Chemicals&id=3792536

P.C. McKenzie Company - http://www.mckenziecorp.com/boiler_maintenance.htm