Thermal deaerator

[larry_s]

The deaerator equipment has steam injected at the top to pressurize it to 0.2 bar, and steam is also injected at the bottom to heat the water temperature to 104°. The engineering details are explained as follows,

In order to prevent the system against shocks by implosion of steam bubbles in case of low feed water temperatures and high flow rates of injection steam, a maximum limit for the manipulated value of the temperature controller is calculated by evaluation of the actual deviation of the measured temperature to the saturation temperature as calculated for the actual tank pressure inside an internal function. - What’s the detailed reason for the steam bubble implosion ?

By comparing the difference between the water temperature and the saturation temperature at the current pressure, it’s used to control the valve opening. This opening value controls the flow of steam entering from the bottom to raise the water temperature. If the difference is small, the valve opens 100% to heat the water. Does a small difference really mean the impact of steam explosion is small?

 

[TBP]

The steam introduced into the deaeration section is to heat the incoming water to the boiling point - at whatever the operating pressure is - so as to drive off dissolved gases, primarily oxygen. Typically, the storage section is unheated. You can do direct steam injection to heat water, but there are some important design & installation considerations - such as a correctly sized sparge line, and the right number of correctly sized & spaced holes in this line. Also this sparge line - and the associated holes - need to be far enough from the sides of the tank to avoid impingement. I've seen steel tanks develop some serious cracks because the sparge system wasn't designed and installed correctly. A steam bubble forming in relatively cold water collapses instantly, leaving a void that is immediately filled by inrushing water - and the resulting pressure spike can be spectacular. There's a lot more to this than just stabbing a steam pipe into a water tank.

 

[larry_s]

The steam introduced into the deaeration section is to heat the incoming water to the boiling point - at whatever the operating pressure is - so as to drive off dissolved gases, primarily oxygen. Typically, the storage section is unheated. You can do direct steam injection to heat water, but there are some important design & installation considerations - such as a correctly sized sparge line, and the right number of correctly sized & spaced holes in this line. Also this sparge line - and the associated holes - need to be far enough from the sides of the tank to avoid impingement. I've seen steel tanks develop some serious cracks because the sparge system wasn't designed and installed correctly. A steam bubble forming in relatively cold water collapses instantly, leaving a void that is immediately filled by inrushing water - and the resulting pressure spike can be spectacular. There's a lot more to this than just stabbing a steam pipe into a water tank.

As the bubbles burst, they leave a cavity, and the water around the cavity sort of slaps into itself as it rushes to fill the space. This phenomenon is called cavitation and is quite noisy.

I feel like this phenomenon is really similar to the implosion of steam bubbles in a deaerator.