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Questions and Answers on Key and Difficult Points of Pure Water Treatment (2)

Sep 19, 2020

1. What are the factors affecting the coagulation effect?

(1) The pH of water: If PAC is added to hydrolyze to produce Al(OH)3 colloid, when the pH is 6.5-7.5, the dissolution is small and the coagulation effect is good;

(2) Water alkalinity: When the alkalinity is insufficient, the coagulant continuously produces H+ during the hydrolysis process, which reduces the PH value and the coagulation effect;

(3) Water temperature: when the temperature is low, the viscosity of water is large, the hydrolysis rate is slow, the formation of flocs is slow, and the structure is loose, and the particles are small and difficult to precipitate;

(4) The composition of impurities in the water: the nature and concentration have a great influence on the coagulation effect.

2. What is the relationship between the form of carbonic acid compounds in water and the pH value?

(1) When the PH value is ≤4.3, there is only CO2 in the water;

(2) When PH value=8.3-3.4, more than 98% are HCO3-;

(3) When the PH value is greater than 8.4, there is no CO2 in the water.

3. The purpose of water treatment in the boiler?

(1) Prevent the water and steam of the boiler body and auxiliary systems from accumulating deposits and corrosion during operation. Improve the heat transfer efficiency of the boiler;

(2) Ensure steam quality, prevent scaling and corrosion of steam turbine components, reduce boiler blowdown losses and improve economic benefits under the condition of ensuring water quality.