Why is deoxygenated water added to medium-pressure steam?

In my opinion, it is necessary to prevent the residual oxygen in water from causing oxidation reactions in metals under high temperature and pressure conditions, thereby affecting the lifespan of equipment and pipelines.

It is to cool down, to reach saturation in terms of cooling.

Could you explain it in more detail? I’m not very familiar with this issue either.

This post was last edited by chenxh123 on 2015-7-16 23:16. Is what the original poster is referring to a thermostat? Medium-pressure steam is superheated steam; using deoxygenated water is intended to convert the steam into saturated steam, and deoxygenated water can also turn into saturated steam. Steam has a high latent heat, I guess that’s why. :)

If it is added at the boiler outlet, it is to appropriately adjust the temperature.

Typical heat exchanger designs are based on the principle of steam condensation for heat release; in other words, they utilize the latent heat of steam to function. It is likely that the steam on your end is superheated; therefore, some deoxygenated water is added before the user to cool it down to a saturated state, or to a temperature about 5-10°C above saturation, before it reaches the heat exchanger. A characteristic of steam condensation in heat exchangers is that the heat transfer coefficient is at its highest when a liquid film is formed as a result of condensation. If the steam pressure remains constant, no liquid film is formed during the superheating and cooling stages; in such cases, the heat transfer coefficient is very low. This not only results in unnecessary use of the heat exchange surface area but also significantly reduces the total amount of heat that can be transferred. Is it clear now? In other words, it is most appropriate for heat exchangers to use steam at the saturation point, but pipeline system control requires superheating in order to compensate for the heat losses caused by thermal radiation from the pipes ； In the design of heat exchangers, there is always a phase of superheat reduction. Therefore, if the superheat level in your company’s pipeline network is too high, it may be suitable to use steam for power generation units such as turbines, but the steam needs to be cooled down when it is used by users who rely on heat exchange.

The water used in boilers is determined based on the required steam pressure; the higher the steam pressure, the greater the degree of oxygen removal. I don’t agree with what was said above. Of course, I don’t know at which stage this oxygen removal takes place, so it’s impossible to say whether what the person above said is correct or not

Convert superheated steam into saturated steam.

I think it’s mainly to prevent corrosion.