Can hydrogen pipelines be purged with steam? Why?
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As the title suggests, I hope experts can provide answers! ! ! ! !
Hydrogen pipelines with reactors cannot be purged with steam, as catalysts can break easily when they absorb water
Hydrogen pipelines are generally not purged with steam, as the medium contains hydrogen and its explosion limit is quite wide. If pipeline work is required, purging with N2 is sufficient; for such purposes, industrial air is used first, followed by nitrogen. ,
Do you mean that oxygen is mixed in with the steam, or is it because the temperature of the steam is too high?
After steam purging, condensed water remains in the pipelines, which can easily cause the catalyst to break down and become inactive.
It is mainly because, after steam purging, there is residual water in the pipelines; when this water enters the reactor, the catalyst absorbs water and becomes brittle, which leads to the catalyst breaking down and becoming inactive. It also increases the pressure drop in the reactor. So, it’s primarily to protect the catalyst
Steam cannot be used; I use air for purging and nitrogen for displacement here
For newly constructed pipelines, steam can be considered under the condition that effective isolation is in place; however, the pipelines must be thoroughly purged before being connected to the system (to protect the catalysts). Air should be used first, followed by nitrogen, so there is no need to use steam – industrial air and nitrogen are usually sufficient； Old installations usually only have nitrogen-based purging lines; of course, if work is to be carried out on hydrogen-containing pipelines, temporary lines can also be used in order to ensure proper analysis and effective isolation. It isn’t just steam that can be used – water washing is also an option. Of course, the system still needs to be thoroughly purged before it is put into formal use.
The explosion limit of hydrogen is relatively wide; I think prohibiting the use of steam for purging is intended to prevent the formation of explosive gases. In actual production, nitrogen is generally used for purging and displacement; steam is only used for displacement when nitrogen purging has been successful and work involving open flames or personnel entry is required.
For simple pipe replacement (only pipes), steam purging can also remove air, but this is possible only if the pipes can withstand the steam temperature; moreover, it’s necessary to find a way to lower the hydrogen dew point~~
The steam ultimately cannot be completely cleaned, and by the time it reaches the reactor, the catalyst will be affected negatively