How are the water quality standards for boilers determined
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Dear friends from Sichuan, I have a question: how are the water quality standards for industrial boilers determined? Why is the pH level to be controlled between 9-11 or 10-12, and how are the ranges for parameters such as boiler water hardness and phosphoric acid determined? If the national standard specifies it this way, then there’s no need to reply. Because I always mix up numbers, I want to find out for sure. Thank you!
It is determined based on the causes, conditions, and degree of scale formation.
You ask how to determine the parameters specified in national standards; this is a bit difficult – it usually relies on experience
Determined based on PH, SIO2, Fe, COD； Keep PH between 9-11 to reduce corrosion of equipment ； The hardness of phosphoric acid is adjusted through routine analysis based on the amount of reagent added.
You want to know how the **standard is determined, right?
For specific scaling factors, calculations can be carried out using chemical principles and stoichiometry; other indicators, which are intended to prevent oxidative corrosion, are also calculated based on the chemical factors involved in corrosion principles. In the case of scaling, it is determined by the product of the concentrations of the cations and anions that cause scaling; factors such as the temperature of the water in the boiler and its pH value also need to be taken into account. Once these influencing factors are identified, the quality parameters for the boiler water and make-up water can be determined. This is because the operation of a boiler also needs to follow certain procedures (here, this generally refers to drum boilers). In the case of DC furnaces, during the operation period, the amount of scale deposition remains within an allowable range, and the water quality is determined based on this allowable range. The water quality requirements for DC boilers are higher than those for drum boilers, as drum boilers can carry out continuous or periodic drainage operations to remove the concentrated water containing scale-forming substances, whereas DC boilers vaporize all of the feedwater into steam.