Heating for hydrogen pipelines

No heat tracing is needed; whether hydrogen is produced by electrolysis or by the cracking of hydrocarbons, water has already been largely removed during its production process – so where could there still be water? Not even the instrument air and plant air in the factory are heated. I don’t know where to start talking about hydrogen carrying water! Generally, the condensation of water vapor is related to its saturated vapor pressure at a certain temperature, that is, to its concentration; the water content in hydrogen should be on the order of PPM.

1. Heat tracing is not required; insulation alone is sufficient； 2. The claim made regarding the second floor cannot be accepted: The hydrogen produced by electrolyzing salt water still contains saturated water even after treatment; if it is transported over long distances, water will precipitate due to temperature differences, which leads to the problem mentioned by the poster

Additional note: If hydrogen is the medium to be compressed at the compressor inlet, it should be heated. Our plant’s hydrogenation unit is equipped with heating to reduce the amount of liquid carried by the hydrogen, thereby preventing it from entering the compression cylinders

It is true that hydrogen still contains water after being cooled and compressed, but there is no need to provide heat tracing for the hydrogen pipes. If water condenses, water removal devices can be installed at all locations where water may accumulate. However, it should be noted that drainage points may freeze in winter; we encountered this problem here this year, with the drain valves freezing up. After installing steam heat tracing tubes on those valves, the freezing issue was resolved

It should be determined based on specific conditions such as local extreme temperatures, hydrogen temperature, moisture content, and the spacing between devices; there is no one-size-fits-all solution. In some areas, insulation alone is not sufficient; heat tracing is also required ； Some insulation is sufficient; the pipes should have a slope, and the distance between dewatering tanks should not be too large ； In some cases, only a dehydration tank is required. In cold regions, after cooling and water removal, it is advisable to install air-cooling tubes and mist eliminators; otherwise, it is also difficult to remove water from the fluid during transportation. I have dealt with ice blockages in the pipes between electrolysis and hydrogen treatment; I didn’t dare to stop the machine for fear that it would be even more difficult to restart it after a power outage. The hydrogen was released directly in the electrolysis plant, and steam was used to warm the hydrogen pipes until the ice melted enough for production to resume. It wasn’t until later that I realized just how dangerous it was.

Our company also faces this issue with hydrogen: using heating elements or not using them is a contradictory approach. Without heating elements, the pipelines are prone to freezing in winter, while the use of heating elements makes it difficult for the water present in the hydrogen to be removed, which affects the proper operation of the compressor and hinders safe production. The best solution is to ensure stable operation of the hydrogen production system; only by achieving stability there can the problem of water in the hydrogen be resolved.

Whether water is present or not may have a lot to do with the compressor. In compressors that use water for lubrication and cooling, a large amount of moisture enters the hydrogen gas during compression. This moisture is then removed through cooling or other methods, but it may not be removed completely, resulting in the hydrogen gas containing a significant amount of water. For locations with high traffic, if freezing still occurs, considering adding insulation should resolve the issue. For locations with low flow rates and at low temperatures, consider adding heat tracing.

Insulation is sufficient; heat tracing is not needed

Hydrogen should be insulated. The pipeline from the liquid separation tank at the inlet of the new hydrogen or recycled hydrogen compressor to the compressor inlet needs to be insulated in order to maintain a constant temperature of the medium at the compressor inlet and reduce the amount of liquid carried by the hydrogen. Additionally, some foreign process packages require insulation at the bottom of the liquid separation tank at the inlet of the recycled hydrogen compressor as well.

In one of the projects I have worked on, for a gasoline hydrogenation unit, most of the hydrogen pipelines were equipped with heat tracing； In a hydroprocessing unit for residual oil after vacuum distillation, some hydrogen pipelines are also equipped with heat tracing ； Both of the devices I mentioned are in the northeast. Whether heating is necessary should be determined on a case-by-case basis.