Air separation equipment has strict requirements for the quality of cooling water, mainly involving suspended solids content, hardness, pH value, oil content, chloride ion concentration and other indicators. At the same time, water temperature, flow rate and pressure need to be controlled to ensure stable operation of the equipment.
Suspended solids content, requirement: ≤ 50mg/L. Suspended solids (such as sediment and dirt) can easily block the cooler channels, filter screens, and valves, affecting heat exchange efficiency and even causing equipment failure. It is necessary to set up sedimentation tanks or use filtration devices to remove suspended solids.
Hardness (temporary hardness), compressor cooling water ≤ 17 ° dH, nitrogen water pre cooling system ≤ 8.5 ° dH (it is recommended to use low hardness water or soft water). Calcium and magnesium bicarbonate in hard water are prone to form calcium carbonate (CaCO3) and magnesium carbonate (MgCO3) scale at high temperatures, which adheres to the pipe wall, packing, etc., reducing heat transfer efficiency and hindering fluid flow. The risk of scaling significantly increases when the water temperature exceeds 45 ℃. Magnetic water softener or ion exchange method should be used to reduce hardness.
The pH value requirement is 6.5-8.0. Excessive acidity (pH<6.5) or alkalinity (pH>8.0) can corrode metal equipment and shorten its service life.
The oil content requirement is<5mg/L. Oil stains will adhere to the heat exchange surface, forming a thermal insulation layer, reducing the cooling effect, and may also breed microorganisms.
The chloride ion concentration requirement is<50 × 10 ⁻⁶ (mass fraction). Chloride ions have strong corrosiveness, especially for stainless steel equipment, which may cause pitting corrosion or stress corrosion.
