Is the expander seal damaged?
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After the expander is heated, all valves are closed, and the oil pump also stops operating; only the seal gas supply remains active. The pressure in the expander increases, which must mean that seal gas is leaking in through the labyrinth seal. Is this normal? Do all expanders also experience all valves closing after heating up?
Bro, the expander here with us is experiencing the same issue; after we shut down the machine, the nozzles and the heating outlet valves open. I think there shouldn’t be any problem, because we didn’t mess with it, and it works fine when driven.
We have encountered this situation before as well; we initially suspected that there was a problem with the expansion turbine’s seal. We brought the manufacturer of the expansion turbine from Sichuan to our construction site, and after spending a week on various attempts to fix it, nothing was resolved in the end. After examining it, we found that the wear on the seal was within normal limits, so there was no actual problem. In operation, the temperature at the expansion end of this expander is slightly lower than that of the one without air leaks, when the rotational speeds are similar. No solution! It can be said for sure that the sealing is fine. There’s no problem running it either; just operate it as you would normally
I’m also working on measures to reduce energy consumption here; it turns out that the expander uses over 300 cubic meters of heating gas per day, which is quite surprising. The original backup unit was constantly heating, so this issue wasn’t noticed. I hope the students can identify any other flaws in this method.
Reply to 4#: What’s its rank in the world? Over 300 per day – is that just the heating gas for the expander? Why keep it on all the time?
It is normal for the pressure to rise after closing the heating and blow-off valve; some of the sealing gas will surely leak into the gas side of the expander, and this cannot be used as an indicator of seal wear
When the sealing gas is not supplied, the pressure inside the machine increases. If a tower is connected to the back of the machine, when the pressure reaches a certain level (around 1 kilogram), the safety valve at the back of the machine will open. If a tower is connected behind the machine, it is necessary to check whether the pressure of the sealing gas will cause the safety valve to activate. Once the machine is heated properly and the sealing gas is not cut off, the blow-off valve of the volute can be opened slightly.
The heating gas volume is also calculated using the pipe diameter and pressure; when the pressure is high, the exhaust valve on the casing is opened. It seems nothing’s wrong. I think a bit of pressure is good too, to prevent moisture from getting in.
Reply to 1# Tianxia Di Ji, bro – it’s normal for this phenomenon to occur. If you study the expansion machine diagrams and flowcharts more closely, you’ll understand the principle behind the sealing air used in the expansion machine； With the inlet and outlet valves of the expander closed, after heating the expander and closing all purge valves, when the sealing gas is supplied as normal, the pressure inside the expander will increase slightly, which is normal. When the oil pump is not operating, the sealing gas flows directly into the oil tank through the return oil pipeline, and is then discharged into the atmosphere via the oil tank’s vent pipeline ； The expander labyrinth seal has connections on both the gas side and the oil side ；
Thanks to your reminder, I forgot about the oil issue; the smoke from the cooking is indeed heavy, and I had been wondering about that. Just call and have Che seal the gas.