Why is there a large amount of free water at the end of the air purification duct network?
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During on-site inspection, it was found that there was drainage of large amounts of free water and rust at the end of the purge air supply in the tank area as well as on the air supply lines of the pneumatic isolation valves for the oil pipelines. Rust formation is understandable; it is caused by internal corrosion of carbon steel pipes and the scouring effect of the cleaning air. But why is there varying amounts of free water? According to the purification air standards, the dew point temperature of the air is generally -30 degrees. My personal judgment is that although the water vapor content in the air has been significantly reduced, a partial pressure still exists; as a result of pressure and temperature conditions at the end of the pipeline network, trace amounts of liquid water precipitate. As it is at the end, there is no gas flow, which causes water volume to keep accumulating. They are also present on the air supply pipelines of those less frequently used cut-off valves, which serves as evidence. Of course, if there are deviations in the operation of the air compressor station, it could also lead to an abnormally high water vapor partial pressure in the purified air, below the design specifications, thereby allowing free water to precipitate out of the purified air; this is a possible scenario, but it seems unlikely. It is doubtful that, as a specialty in instrument maintenance, there are no explicit regulatory requirements regarding the inspection and maintenance of instruments and control valves What do you all think? Please give me some advice! ! !
It is likely that the dew point of the purified air is too high, causing liquid water to precipitate at room temperature. Generally, different types of air compressors result in different dew points for the purified air produced.
We encountered a similar problem with the boiler; at that time, the supervisor explained some theoretical concepts, but they weren’t convincing. It was eventually determined that the issue stemmed from the pressure supply point located at the bottom of the equipment, which shared the same inlet as the air used for stirring. When the equipment was in operation, pressure was released, and there were always fluctuations in air pressure. By moving the pressure supply point to the upper part of the equipment, the problem was resolved.
Thank you so much for participating! Our facility is located in Shandong, and the outdoor temperature is currently around 30 degrees. This month, the dew point temperature of the purified air in our facility has frequently been in the teens, or even 30 degrees, which is 10-15 degrees lower than the temperature of the surrounding air; at times it’s even less than 5 degrees lower. We suspect that there is dirt on the probe of the dew point meter, and after cleaning it, the temperature difference between the two values dropped to 20-25 degrees. The process uses compressor technology and does not employ freeze-drying. Checking HG/T20510, there is a problem: the standard requires that the dew point temperature be 10 degrees lower than the local extreme temperature. Does this refer to the coldest temperature during winter throughout the year, or the coldest temperature in the current month? For example, in summer when the outdoor temperature is above 35 degrees, is it sufficient to require that the dew point temperature of the purified air be at 20 degrees?
Is the mild heat drying system effective? Check it to see if the drainage is working properly. Also check the bottom of the buffer tank to see if there’s any water there
If there is no seal at the pipe opening or if the valve is not closed, some moisture will accumulate, which over time leads to the formation of condensation water. This is a normal phenomenon; it can be resolved by using dry gas to purge the area.
Thank you first, I’ve learned it. In winter, condensation of instrument air can cause the control valves to open or close fully. In fact, what seems like a small issue can have a very significant impact. If it is indeed due to dew point, we can add insulation or heat tracing to the key valves to raise the temperature of the air. Enhance drainage at the lowest points.
In response to this situation, I believe there are several factors that need to be taken into consideration: 1. Whether the data on the dried air coming out of the dryer is accurate; as far as I know, many dryer manufacturers, in order to save costs, opt for dew point meters whose readings are favored by everyone； 2. How is the interior polishing of the entire pipeline, especially in the sections where problems occur? Are there any burrs or similar elements that could lead to water retention? 3. The pipeline design should avoid dead zones; more purging ports should be installed, and pipe cleaning operations should be intensified during actual operational conditions ； For issues related to dew point and gas analysis, please send messages to me at yh@tyrande-sc.com; we specialize in solving all kinds of humidity problems.