Process flow and principle of the boiler feedwater chemical dosing system

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This post was last edited by B0SS on 2017-9-2 at 18:10. Process flow and working principle of the chemical dosing device for boiler feedwater; chemical dosing system for boiler water treatment. The calcium and magnesium hardness in boiler feedwater can undergo chemical reactions or concentrate and crystallize under high temperatures, resulting in insoluble scale that adheres firmly to the heating surfaces of the boiler. Such scale is a poor conductor of heat, which hinders heat transfer; in severe cases, it can cause boiler tube failures. Additionally, it induces and exacerbates chemical corrosion of the metal beneath the scale, posing serious hazards. The boiler feed water dosing equipment produced by Shanshui Environmental Protection Machinery meets **standards, and it can be configured according to your actual needs. The ammonia addition unit in the process flow consists mainly of a solution tank, an ammonia addition metering pump, an electrical control cabinet, a mixer, a magnetic flap level gauge, a safety valve, a check valve, a flow calibration column, a pulse damper, a Y-type filter, a needle valve, a ball valve, a drain valve, a pressure gauge, an ammonia mist absorption device, cables installed inside the equipment, an equipment base, and a support platform. Ammonia water is drawn into the solution tank by a water ejector, and then added to the tank in proportion to be mixed evenly with deionized water or condensed water. It is subsequently supplied to the boiler’s condensed water or feed water via a metering dosing system. Dosage control can be performed manually, or it can be automated based on the control signals output by the upper-level system. The working principle is as follows: Free CO2 in water can make the water acidic, through the reaction CO2 + H2O → H+ + HCO3-. The H+ ions in such water can cause hydrogen-depolarized corrosion in metals such as carbon steel, leading to damage to iron components; the reaction is as follows: H+ + 2e− → H2, and Fe → Fe+ + 2e−. Especially in chemically desalinated water with high temperatures and no buffering capacity, free CO2 **accelerates steel corrosion; therefore, it is necessary to suppress this electrochemical reaction. Adding ammonia to water raises its pH value, which can effectively suppress the dissociation of H+, thereby controlling metal corrosion.