Re: Leakage Air From Rotary Seal
Is the blowing seal vented at all? If you are not venting the blowing seal correctly then the leakage air (which may be excessive) must go somewhere. This will ultimately be up through the silo which may also cause problems with filling and throughput of the valve.
I run and engineering consultancy business that specialises in pneumatic conveying systems. I can advise on system and component design ans if required viist site to analyse you systyems and make recommendations.
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Re: Leakage Air From Rotary Seal
Dear sinclasc,
Although the information you supply is not extensive, I understand that the silo has over pressure while unloading at the bottom.
If no air is supplied to the silo, one would expect an under pressure.
Probably there is fluidization air injected to the material, causing an over pressure in the silo.
To prevent dust escaping from the top, there are 2 options:
-make the top 100% sealed. In case the over pressure increases to a too high level the safety valve must become active and dust is released. (no way around it)
-Install a filter on top of the silo with a de-aeration fan of sufficient size. This fan creates an under pressure in the silo and dust cannot escape from the silo against the incoming air through possible openings.
If the rotary seal is leaking dust, than the rotary seal is worn or not fit for the application or another method of retracting material from the silo should have been chosen.
success
teus ■
Teus
Re: Leakage Air From Rotary Seal
Ask the rotary valve manufacture for the air leakage curve you know the pressure in the conveying line, this will give you air leakage. Remember air leakage is also dependent of valve conditions. Generally for 200-250 dia. RV you are looking at 80 -120 m3/hr. It is clear that your filter is not coping with the duty so is it insufficient filter area, blind cartridge or worn out rotary valve?
I would also recommend a fan assisted filer on your silo as it will solve the leakage problems, ■
Re: Leakage Air From Rotary Seal
If there is a pressure difference between the inlet and outlet of the valve then the high pressure is carried round the rotor between the vanes of the valve. This does not mean that seals are leaking. This pressurised air is normaly vented either into the silo or to a venting device mid way around the valve.
If you are venting into a sealed silo there is a serious risk of damage to the silo integrety or even a potential pressure induced rupture.
Your options are simple, vent the silo or fit a rotary valve with a venting device that does not relieve into the silo. ■
Leakage air from rotary seal
Hi all,
At the bottom of my silos I have a rotary valve / blowing seal.
When pulling material from the silos air is blown past the seal thus tranferring the material to a new location.
During this process however powder can be seen clearly leaking from the tops of the silos by different routes; the infeed valve, the inspection hatch, the pressure relief valve. There is a pressure relief filter (single cartridge type) which is rated for "normal conditions" and has clean filters, however is incapable of displacing the air.
Is there a way to see if the leakage air past the blowing seal is normal or excessive? ■