How should the amount of hydrazine added to boiler feed water be determined?
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RT: The hydrogen boilers in use at the facility are equipped with thermal deaerators, with a temperature setting of 104°C. However, test results show that the dissolved oxygen level is 1.5 mg/L, which is well above the acceptable limit. It is now necessary to add hydrazine to further remove oxygen from the water. But how should the concentration and amount of hydrazine to be used be determined? I would appreciate advice from all of you experts. Thank you! It is preliminarily determined that ammonia should be added before entering the deaerator, and hydrazine should be added at the outlet of the deaerator – is this approach correct? I don’t know how to determine the concentration and amount.
Ammonia and deoxidizers must be added to the feed water of steam boilers to ensure water quality safety. Ammonia is added to the feed water to raise its pH value, and the dosing point is located at the outlet of the deaerator. If ammonia is added before entering the deaerator, it will decompose at high temperatures and be released into the atmosphere along with the deoxygenated gas. Hydrazine is a type of deoxidizer; adding hydrazine to the feed water serves to remove residual oxygen from it, and the dosing point is located at the outlet of the deoxidizer. Hydrazine also has the drawback of decomposing into ammonia and nitrogen at high temperatures; therefore, the dosing point is located at the outlet of the deaerator, before the feed water pump. If it is not a power plant boiler, the water quality concentration shall comply with the standards specified in GBT_1576 for industrial boiler water quality. For the dosage, please refer to books on water treatment.
The deoxidizer should be added at the inlet of the deoxidation tank, while ammonia should be added in the pipeline between the deoxidation tank and the water pump. Can the concentration and flow rate be determined based on the oxygen concentrations and pH values of the inlet desalinated water and the outlet water?
OP, how are you guys adding hydrazine now?
No hydrazine is being added at the moment… The water quality parameters are within acceptable limits; it’s just that the pH level of the boiler water is low, around 8-9, with everything else being normal