The hardness of calcium and magnesium in the boiler feed water will be chemically reacted in a high temperature environment, or concentrated and crystallized to form insoluble scale, which is firmly attached to the heating surface of the boiler. This scale is a poor conductor of heat, which may hinder heat conduction and may occur in severe cases. Boiler blasting accidents, in addition, will induce and aggravate the chemical corrosion of metal under the scale, and the damage is quite serious. Although the boiler condensate and feed water have undergone strict softening and desalination treatment, there is still a small amount of calcium and magnesium hardness entering the furnace water. If this part of the hardness is not treated, the scale will also pose a threat to the safe operation of the boiler. At present, furnace water plus phosphate is the most suitable treatment method, the reaction is as follows:
10Ca2+ +6PO43- +2OH- =Ca10(OH)2 (PO4)6
(basic calcium phosphate)
Alkali-type calcium phosphate is a kind of soft water slag, which is easy to be removed with boiler blowdown and does not adhere to the pot and becomes scale.
Function introduction of automatic control system: In the automatic control state, the system automatically adjusts the speed and stroke of the metering pump according to the signal of flow rate, PH value and phosphate value through PLC, host computer or DCS. The metering pump flow adjustment range is 0~100. %, the inverter's speed control input signal is a standard 4 to 20 mA signal, and the feedback signal is also a 4 to 20 mA signal. The status and fault signals of all metering pumps and mixers can be transmitted to the DCS or the host computer as needed. The DCS or the host computer can remotely start and stop the dosing pump as needed.
? According to different technical requirements, the electric control cabinet can be equipped with local manual control, semi-automatic control and fully automatic control.
? The over-current material can be made of 316 stainless steel or 304 stainless steel according to different corrosion resistance requirements.