Discussion on the unqualified conductivity of deoxygenated water from the deaerator
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Dear sea friends, welcome to engage in lively discussions. The details are as follows: We have two deaerators here, one of pressure type and the other of atmospheric type. These days, the conductivity of the steam in the company’s pipeline system has been below the required standards, so we started investigating from the source. Since this transformation unit is a major steam producer, upon analyzing the steam at various pressure levels, the conductivity of the lower-pressure steam (0.46, 1.1 MPa) was above 10 us/cm in all cases, while that of the higher-pressure steam was above 20 us/cm. It was found that the conductivity of the deoxygenated water coming from the atmospheric deaerator was above the specified limit, approaching 30, whereas the conductivity of the deoxygenated water from the pressure deaerator was around 6. Note: All low-grade steam is produced from deoxygenated water generated by atmospheric deoxidizers. The hydrazine concentration in atmospheric deoxidizers is around 20, with a pH value between 9.5 and 10, while the hydrazine concentration in pressure-type deoxidizers is around 5, with a pH value between 9.0 and 9.5. Is it the hydrazine concentration in the deoxygenation chemicals that affects its conductivity?
Of course, there is an impact: when hydrazine (i.e., hydrazine hydrate) dissolves in water, it becomes alkaline and thus contributes to the conductivity. Other polar pollutants can also contribute to the conductivity of water.
Have you guys experienced this too? Does it have a lot to do with the pH value?
We don’t experience this phenomenon; you can try reducing the amount of hydrazine added, and then check whether the conductivity decreases once the pH value drops. Or try injecting a small amount of steam into the atmospheric deaerator.
After adjusting the pH of normal deionized water, the conductivity is around 2, and it doesn’t become very high even after adding hydrazine. Contamination of the condensate or steam can also affect the electrical conductivity of the boiler water.
Atmospheric deaerators are also heated by steam; we are conducting experiments on them these days
Oh, I see. You mean the heating steam in the deaerator is of poor quality, with a conductivity level that exceeds the standard, is that right? Perhaps that’s the reason; thank you very much