Regarding the dosing concentration of deoxidizers in boiler water
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For low-pressure boilers, the deoxidizer used is hydrazine (hydrated hydrazine with 80% purity). What is the typical concentration of hydrazine used in low-pressure boilers? What is the oxygen content in low-pressure boiler water, in ppm, under normal conditions?
The oxygen content in boiler feed water is expressed in ppb, typically ranging from a few to several dozen ppb. When adding deoxidizers, it is also not advisable to use too much of them. The concentrations of dissolved oxygen and hydrazine can be monitored using online analyzers, which provides accurate reference data for the boiler feedwater.
The lower the dissolved oxygen level in the boiler, the better. Generally, hydrazine is added with the aim of removing oxygen from the water. Therefore, there is no fixed amount specified for its addition; instead, the amount of hydrazine to be added is determined by measuring the residual amount of hydrazine in the water, with the goal of keeping this residual level at around 1 ppm
The lower the dissolved oxygen level in the boiler, the better. Dissolved oxygen can cause oxygen corrosion within the boiler, and as this corrosion progresses, iron oxide scale with extremely poor thermal conductivity forms on the inner walls of the boiler, which can lead to tube failures or even explosions. The purpose of adding hydrazine is generally to remove oxygen from water; therefore, there is no fixed amount specified for its addition. Instead, the amount of hydrazine to be added is determined by testing the residual level of hydrazine in the water, with the goal of keeping the residual amount at around 1 ppm