Liquid nitrogen cleaning to remove blockages – experts needed
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Liquid nitrogen washing occurs occasionally; when the molecular sieve is used along with a small valve left open for about two hours, the raw material gas pipeline freezes up and the pressure difference increases. It was operating normally after three hours; please find the reason. Preliminary assessment indicates that the methane concentration is around 1500 PPM; methane discharge can cause freezing and blockages. Leakage of heated gas generated during production may also lead to methane release. The dew point temperature of the regenerated nitrogen is -70, and carbon dioxide levels are below 2 PPM
Where does raw gas freezing blockage occur between the heat exchangers?； Has there been any change in the temperature between heat exchangers 02 and 03?
In the image above, that area is blocked; what is the load?
Normal; there is a significant temperature difference between 04 and 05. It is preliminarily determined that the feed gas has caused freezing and frosting in the pipes at E05, which has led to a reduced heat exchange efficiency
At full load, the feed gas causes freezing and blockage in the internal pipes of E05, resulting in an increase in pressure difference
Since it occurs occasionally, it is recommended to consider the possibility of a molecular sieve system
The online analysis of the molecular sieve system has been functioning normally; whenever a problem occurs, manual sampling for analysis is carried out, and the levels of water, carbon dioxide, and methane are all within normal ranges
The methane level is too high; adjust the temperature of the gasifier
The methane level isn’t high; it’s fine to pass it through liquid nitrogen treatment even if it’s around 2500 ppm, while ours is only around 1500 ppm