Difficulties in boiler water treatment
There are three important problems that need to be solved and controlled in the normal operation of the boiler
1. The formation of scale. It will affect the boiler heating effect, increase energy consumption, and produce slag.
2. Water quality and steam quality. Bring impurities to the production process and affect product quality.
3. Internal corrosion of metal materials. Cause damage to the surface of equipment and pipelines, fail to work normally, and affect production efficiency.
The above problems are fundamentally caused by water quality, so they must be treated frequently to meet boiler water requirements and maintain circulating water quality.
1. Untreated inlet water (including supplementary water) has high calcium and magnesium ion content and high hardness. Under high temperature conditions, it is easy to combine with CO2 and H2O, and chemically react to form insoluble CaCO3 and MgCO3, forming scale. At the same time, the ammonia, nitrite, hypochlorite and other acid ions contained in the water will easily react to produce ammonia, nitrogen dioxide, chlorine dioxide, etc. and water vapor under long-term high temperature. If they are directly used in factory production , The formation of by-products (impurities) affects the purity and quality level of the product.
2. Even if the softened boiler water is repeatedly used in the process, due to the evaporation of high-temperature water vapor, the accumulation of salt, and the concentration continues to rise, its water quality gradually declines. Some factories artificially added chemicals such as scale removers and scale inhibitors are also accumulating impurities.
3. Incorrect treatment methods cause excessively acidic or alkaline pH of the water, which is likely to cause internal corrosion of the metal substrates of boilers and pipelines. More metal ions dissolve into the water, and TDS keeps increasing.
Boiler water treatment methods commonly used in most factories.
By adding a scale remover to remove the scale that has formed, and then discharge the sewage, use a composite scale inhibitor to preferentially chelate the calcium and magnesium ions in the water, without reacting with CO2, H2O, and prevent the formation of scale.
Adopt hydrogen or sodium cationic resin to release sodium ions or hydrogen ions to exchange with calcium and magnesium ions in the water to eliminate the generation of scale. It is also necessary to use hydroxide-type or sodium-type anion resins to release sodium ions or hydroxide ions, exchange them with acid ions in the water, and maintain the balance of anion and cations in the water to prevent the pH from being too acidic. The usage ratio of anion and cation resin is generally 2:1 (volume ratio).
Using RO treatment, the removal rate of soluble salt, organic matter, and insoluble suspended matter in the water is as high as 97% or more, and it becomes ultrapure water. When used in a boiler, there is no such problem. But RO is not suitable for online high-temperature boiler water treatment.
To solve the above problems, a single method cannot satisfy all of them. Usually, a combination of multiple methods is used to achieve the best results. It can be seen that boiler water treatment is not just about removing scale and preventing scale generation. It should pay attention to water quality test data and adopt corresponding treatment methods, especially the following items:
The treated water quality meets international standards
Hot water boiler
Content of calcium and magnesium ions
Content of acid radical ions
Refers to the pH of water
Total dissolved inorganic matter
Total dissolved organic matter
chloride ion content
Correct water treatment methods and steps
1. Measure the above indicators of influent and circulating water quality.
2. Develop treatment combination plans and steps based on water quality indicators.
3. Calculate the usage of various chemicals and resins.
4. Follow the scheduled plan and steps
5. Check again whether the above indicators of the treated water meet the standards and plans.
6. If the target is not reached, analyze and process again until it is completed.
7. Fill in the treatment record, submit the treatment report, and allow the boiler to be used normally.
Different water quality should be treated differently. Based on actual data, flexible formulation of plans, implementation of daily water quality inspections, and establishment of water quality treatment records are scientific, rigorous and effective water treatment management.
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