Pressure Reducing Stations
Pressure Reducing Stations
(OP)
Hi all,
I recently posted a question about nitrogen purging calculations in this forum. Im glad to say that I have resolved my earlier question, but I now have something of a follow up!!
On our plant, we are planning on generating nitrogen at 6-8BarG, distributing it at 3BarG and supplying it to our vessels for inertion/purging/blanketing etc at 25mBarG.
My question is this:
Does anyone have any operational/design experience that would allow them to advise me on the appropriate number of pressure reducing stations that would be required to reduce the pressure from 3BarG to 25 mBarG and to maintain an accurate control of the N2 pressure around the set point (25 mbarG).
I have spoken to different people within my department, nad have, in general, been told one of two things;
1)It is not possible to reduce from 3 BarG to 25 mBarG and maintain accurate control around a set point. What I should do is have two stations, one to go from 3 to 1 BarG and then a second to go from 1 BarG to 25 mBarG.
2)There is no reason why I couldnt reduce from 3BarG to 25mBarG in one go and still maintain accurate control around my set point.
The reason that an accurate control is of such concern is that the vessel is not designed to handle much over pressure, and there is a conservation vent set at 30 mBarG.
If anyone has any suggestions as to how I should proceed, I would be most interested in hearing them.
Regards
Niall
I recently posted a question about nitrogen purging calculations in this forum. Im glad to say that I have resolved my earlier question, but I now have something of a follow up!!
On our plant, we are planning on generating nitrogen at 6-8BarG, distributing it at 3BarG and supplying it to our vessels for inertion/purging/blanketing etc at 25mBarG.
My question is this:
Does anyone have any operational/design experience that would allow them to advise me on the appropriate number of pressure reducing stations that would be required to reduce the pressure from 3BarG to 25 mBarG and to maintain an accurate control of the N2 pressure around the set point (25 mbarG).
I have spoken to different people within my department, nad have, in general, been told one of two things;
1)It is not possible to reduce from 3 BarG to 25 mBarG and maintain accurate control around a set point. What I should do is have two stations, one to go from 3 to 1 BarG and then a second to go from 1 BarG to 25 mBarG.
2)There is no reason why I couldnt reduce from 3BarG to 25mBarG in one go and still maintain accurate control around my set point.
The reason that an accurate control is of such concern is that the vessel is not designed to handle much over pressure, and there is a conservation vent set at 30 mBarG.
If anyone has any suggestions as to how I should proceed, I would be most interested in hearing them.
Regards
Niall





RE: Pressure Reducing Stations
Few choices exist with these regulators for the soft goods. Check the regulator elastomeric and plastic parts for material compatibility with the fluid in the vessel. Assume that the regulator will be exposed to that fluid not just nitrogen.
RE: Pressure Reducing Stations
I've seen inert gas holders of the bell-shape floating type that serve as pressure-controlled gas reservoirs, the pressure being controlled by weights on the (water) floating bell, their volume sufficient for a 24- to 48-hour supply of gas. Breather valve protection, nevertheless, has to be given to atmospheric inert-gas blanketed tanks in line with what JLSeagull says.
These type of gas holders are called 'gasometers' in Europe and used for the distribution of fuel gas.
RE: Pressure Reducing Stations
RE: Pressure Reducing Stations
http://www.grothcorp.com/3011.htm
>>2)There is no reason why I couldnt reduce from 3BarG to 25mBarG in one go and still maintain accurate control around my set point.<<
I think that would be true but it would be easier with a small valve than a large one. Example: Scuba tank regulators. Admittedly dual stage, but the final stage takes a vastly greater drop than 3 bar. And having it go overpressure migh ruin one's day.
RE: Pressure Reducing Stations
Good luck,
Latexman
RE: Pressure Reducing Stations
Do not forget the tank over-pressure protection. Tyco, Groth and Protectoseal are also among those who sell this sort of stuff.