High Temperature Pilot Plant PSVs 1

[gkennedy34]

I'm looking for high temperature PSV options for a pilot plant (i.e. small). Design conditions are 1200 deg. F and approximately 80 psig. The highest temperature PSVs I've found are only rated for about 750 degrees F. If anyone has any firsthand knowledge or any ideas about how to deal with this situation, please comment.

I realize that we could move the PSV away from the vessel with a short run of tubing and get the temperature down quite a bit, but then I've gone against best practice by puting a tubing run between the vessel and the PSV!

Help!

 

[insult2injury]

Power boiler (Section I) valves are commonly rated at high temperatures.

I2I

 

[moltenmetal]

If putting an oversized PSV on the unit doesn't represent process problems, you'll have more likelihood of finding a suitable valve.

As long as you don't have a solidifying/polymerizing material that could plug the PSV inlet, and you stay within the 3% rule for inlet pressure loss, there's nothing wrong with putting an impulse line on a relief valve inlet to reduce the PSV's exposure temperature. "Best practice" shouldn't be followed if it causes a harm worse than it solves.

If you do have a solidifying/plugging material to worry about, consider a rupture disk.

 

[gkennedy34]

Thanks for the replies, all! I'll carry this information with me to our pending meeting on this topic.

 

[JoeWong88]

gkennedy34,
I don't quite understand what you trying to do.

Are you saying that you would like to install a PSV rated at 750 degF on a system with design temperature of 1200 degF ? If my understanding is correct, do you think this is allow by regulation ?

PSV rated at 750 degF. What does this mean ? Does it mean the maximum allowable working pressure is 80 psig at 750 degF or there are component e.g. soft seat which will damage when it see 750 degF ?
In both cases, whenever the PSV is popped open, the PSV will potential experience 110% x 80 psig at 1200 degF (may be slightly lower), i doubt the PSV can take this condition.

In you cases, please find a PSV good for your design condition. If not, you may consider Rupture disc. Your design condition is very challenging and high hazardous. If can not be avoided, may consider HIPPS system...

 

[gkennedy34]

The process is at 1200 deg F and the concern about the PSV is that there are elastomer seats which are only good up to 750 deg F. I am looking for a metal-to-metal seated relief valve which can handle the higher temperature or I am proposing using what moltenmetal called an "impulse line" to allow for cooling.

I have discovered a technical paper and have performed some natural convection calculations (there are some available on the web as well) which confirms that the temperature should drop considerably with very little length of "impulse line" used.

In any case, we have not yet determined what we will do.

 

[insult2injury]

Metal-seated SRVs for temperatures up to and in excess of 1200F are commonplace for utility boilers in the power industry. You shouldn't have a hard time finding them.

I2I