Natural gas pipeline replacement plan
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The boiler uses natural gas as fuel, and it is necessary to introduce natural gas into the system before the first trial run. The DN150 pipeline runs for about 500 meters to reach the device, with a pressure of 0.2 Mpa; the pressure inside the device is reduced to 30 kpa. How should gas pipelines be replaced? Introduce nitrogen to reduce the oxygen content to below 0.5%, and then introduce natural gas? When replacing nitrogen with natural gas, can the mixed gas be discharged directly? What are the potential risks or hazards associated with discharging natural gas? Fire is prohibited on site. Are there any other things to be aware of? Is it necessary to dry the pipeline before replacement, and are there any standards for this? Thank you
1. I think your nitrogen displacement plan is fine. 2. Does natural gas not have any smell? When using natural gas to displace nitrogen, it is difficult to determine when the displacement is complete by relying on venting. 3. Dry? What was the condition of the pipeline before you replaced it with nitrogen?
It’s not that complicated; don’t worry, just proceed with the replacement boldly.
This post was last edited by *nht1 on 2015-9-13 at 11:29. Using nitrogen for purging is a reasonable approach; when starting up for the first time, it’s advisable to wash the pipes with water first to remove rust, otherwise the natural gas filter may get clogged. After that, blow dry the pipes with compressed air, and then introduce nitrogen. Maintain pressure and check for leaks at the flanges to ensure that the pressure matches that indicated on the pressure regulator. Once everything is normal, drain the air, turn off the drainage valve, turn off the nitrogen supply, and start using natural gas. Monitor the pressure, and after draining the air for a few minutes or so, turn off the drainage valve again. Note that trace amounts of thiol are present in natural gas, as informed to us by the gas company; therefore, it can be detected by smell, and this odor is indeed present on site. I hope this information is useful to you. PS: By the way, what is your natural gas flow rate? Our flow rate is below 200 Nm3. We haven’t used nitrogen for purging; we simply use natural gas for purging, drain the air, and then ignite it.
The moisture inside the pipeline must be blown dry to prevent affecting subsequent systems; if there is an abundance of nitrogen, it can be used directly to remove moisture and purge the pipeline (ensuring that the oxygen content is less than 0.5%). There should be a natural gas venting site, right? It is generally equipped with a flame arrester. Natural gas contains thiols (odorants), which can be detected by smell~~
The pipeline is new and has undergone a hydrostatic test; is it necessary to measure the dew point? There is an ample supply of nitrogen and compressed air, so they can be used freely. The concern is whether releasing natural gas directly could cause harm, such as environmental pollution or explosions; flame arresters should be installed at the ends of the pipes for high-altitude discharge. Thank you
Will it explode? Or pollute the environment?
Do natural gas companies also release the gas directly into the atmosphere? Other systems use flares to burn the gas, but ours don’t have pipelines connected to flares; therefore, there is a risk of explosion or environmental pollution
What should the moisture content be? Is it necessary to measure the dew point?
This post was last edited by *nht1 on 2015-9-13 21:49. Master, it turns out to be a thiol; the claims made by the natural gas company are unreliable – they’ve been deceiving me for years. But it doesn’t really matter; I hope someone more knowledgeable can give some advice
Our volume is low – only 150-180 Nm3 per hour – so not much can be discharged; a small amount is released each time