Why is it necessary to control the concentration of metal ions such as copper and iron in desalinated water and deoxygenated water?
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The test parameters for demineralized water and deoxygenated water include limits for the concentrations of copper and iron ions. In my opinion, the concentrations of these metal ions should be extremely low after several processes of flocculation, filtration, and reverse osmosis; the units used to express these concentrations are ppm. Is it really necessary to set such limits? Also, may I ask what are the pollutants that metals cause to water and equipment?
In high-temperature and high-pressure environments, if the levels of copper ions and iron ions are too high, it may lead to problems such as corrosion. Although the amount is small, it can cause equipment failure over time. It's a personal interpretation.
The presence of metal ions in water can create a galvanic cell effect with the metals in the pipes, leading to corrosion. Furthermore, if metal ions are present after membrane treatment, it indicates that the treatment was not effective; the concentration of metal ions after such treatment should be at trace levels, as it is demineralized water, which means that the salts in the water have been removed.
According to available information, medium-pressure boilers are generally equipped with turbines. Requirements regarding water quality in terms of metal ions and silica exist mainly because these substances can cause corrosion and salt deposition in the turbines. Our factory has installed two new sets of medium-pressure boilers, but they are not equipped with turbines. If we do not consider the long-term effects of corrosion and salt deposition on the pipes and boiler structures, is it possible to waive these requirements?
Does the medium-pressure boiler come with a superheater? If it is equipped with a temperature reducer, is it surface cooling or mixed cooling? Mixed cooling requires high standards for water quality in order to prevent salt buildup in the superheater ； Based on the experiences of various users, surface coolers can leak after being in use for some time due to thermal expansion and contraction; it is best to have high requirements regarding water quality.