The control of industrial boiler water parameters is the core of ensuring the safe operation of boilers and extending equipment life. It is necessary to strictly follow the "Industrial Boiler Water Quality" (GB1576-2018). The core parameters and control requirements are as follows:
The pH value affects boiler corrosion and scaling. The national standard for feedwater requires 8.8-9.2, and the boiler water should be controlled within 9-11 (not exceeding 12). Abnormal pH is often caused by the hydrolysis of organic matter colloids in raw water and the hydrolysis of resin polymer organic matter to produce acid. If it is too low, it is prone to scaling and accelerated corrosion, while if it is too high, it can cause alkaline corrosion of pipelines. At the same time, pH regulation is needed to reduce the carrying capacity of steam silicate and ensure that phosphate ions react with calcium ions to generate easily discharged sewage sludge.
Conductivity reflects the ion content in water and is related to the discharge rate and dissolved solids. The standard for water conductivity is 0.3 μ S/cm (applicable to boilers with steam pressure<2.5MPa), and the boiler water is classified according to pressure: low-pressure boilers (≤ 1.0MPa) ≤ 1400 μ S/cm, medium and low-pressure boilers (1.0-3.8MPa) ≤ 1500 μ S/cm, medium and high-pressure boilers (3.8-9.8MPa) ≤ 2000 μ S/cm, and high-pressure boilers (>9.8MPa) ≤ 2500 μ S/cm. Exceeding the standard will increase the risk of equipment operation.
Dissolved oxygen requires strict deoxygenation, and deoxygenation facilities must be installed for steam boilers with an evaporation rate greater than 2t/h and hot water boilers with a rated power of ≥ 4.2MW. The qualified standards are divided according to pressure:<5.83MPa boilers<15 μ g/L,>5.88MPa high-pressure/subcritical boilers<7 μ g/L, supercritical and above boilers<5 μ g/L, to avoid oxygen accelerated metal oxidation corrosion.
sodium ionThe standard is ≤ 10 μ g/kg, and an appropriate amount can prevent corrosion and control scaling. Exceeding the standard will accelerate corrosion, increase the risk of scaling, and affect steam quality.
Total hardness/total alkalinityThe hardness of the water supply is generally ≤ 0.03mmol/L (for hot water boilers ≤ 0.6mmol/L), and the total alkalinity (bicarbonate concentration) is 100-500mg/L. The specific range is determined according to the boiler pressure, and the pH can be adjusted for corrosion prevention.
phosphate radicalControl at 0.3-2mg/L, too low cannot remove calcium scaling, too high wastes chemicals and causes salt accumulation in furnace tubes, affecting heat transfer.
Silicate radicalBoiler water/circulating water in thermal power plants has a silica content of ≤ 250 μ g/L and steam water content of ≤ 25 μ g/L. Exceeding the standard can easily form silicate scale and cause furnace tube leakage.
These parameters need to be accurately monitored online to ensure compliance with national standards, especially in scenarios such as thermal power plants. Parameter control is directly related to safety production and power generation efficiency.