Destination of compressor isolation air
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May I ask, does most of the isolation air from the compressor go into the oil sump through the oil return pipeline?
This post was last edited by liuyudzh on 2017-2-10 at 11:33. Before the unit starts operating, isolation gas is introduced to prevent lubricating oil from entering the dry gas seal system and contaminating the seal surfaces; nitrogen is generally used as this isolation gas. Before starting the machine, it prevents lubricant from leaking into the collective; after starting, it prevents lubricant from entering the dry gas seal. Go to the site and take a look at the dry gas seal; there should be a pipeline that leads to the atmosphere for venting.
Hello, according to the PID markings, the flow rate of the isolation gas is 20 Nm3/h, but only 10 Nm3/h flows into the atmospheric vent – so what happens to the remaining gas? So I think it flowed into the lubricating oil; I’m not sure if that’s correct
The isolation gas serves to prevent oil from entering the dry gas seal; it creates a membrane that separates the oil. Some of this gas will inevitably mix with the oil, but instead of some going into the atmosphere and some returning to the oil tank, it is necessary to maintain a certain pressure in order to ensure sealing effect – without such pressure, there can be no sealing action.
You’re right; it’s necessary to maintain a pressure of several tens of KPa to ensure that oil doesn’t get into the dry gas seal. However, the flow meter shows readings, indicating that nitrogen is being continuously added, which in turn means that nitrogen is also being consumed. So, what I mean is that part of the nitrogen went into the oil circuit pipes, while part of it was released. Is the above understanding incorrect?
Those that cannot return to the fuel tank are divided into two parts; they have comb-like structures inside, and the gas from them mixes directly with the air leaking from the secondary seal before being released into the atmosphere. On the other hand, I’m not sure where yours is from; the dry gas seals designed by Sichuan Nikki Sealing are such that they mix with oil to form an oil-gas mixture. Since that mixture generates heat, there is a short oil and gas pipe next to the cylinder, through which the oil-gas mixture is discharged directly. An oil retention device located at the upper part of this pipe ensures that the oil flows back into the cylinder, while some of the oil-gas mixture is discharged on-site. Please take a close look at the device in use to see if this is the case, and also let me know what type of dry gas seal you have.
Another portion of the isolation gas did not enter the lubricating oil; to be precise, some of it was expelled along with the fumes from the lubricating oil tank’s exhaust fan.