Superheated Steam

Sorry, I am not your company's consultancy service.

If this is for that hydroprocessing project you mentioned previously then have you asked them these questions?

You need to retain a properly qualified consultant.

Getting answers from total strangers who are unknown to you and your client

could prove deadly, even though there may well be highly qualified members here.

This is not homework, is it?

1. Valves should be suitable for the service. A valve supplier will be happy to help. I think a single valve even so the application is unknown will never be enough. You will very most likley need more than one valve
2. Is "letdown" a technical term?
   I found this http://www.spiraxsarco.com/resources/steam-engineering-tutorials/desuperheating/basic-desuperheater-types.asp
   This could give all the answers needed

Have fun!

Good reference...

"Letdown" is a standard industry term used all the time Stateside.

"Letdown Station" is what we call a pressure reducing valve (with controler), by-pass, and steam trap.

-A-

Thanks Smith.

Lyn and Jack@ Thanks for You as well. This a not a question related to any project.

This just a general question.

When i checked i found that velocity was very high. I think in general the maximum allowed velocity for steam application is around 180-230 feet/sec

But here it seems its very large..I think the flow here is wrong.. Do any one agree to me here..

Using your data of 4 Barg, (which would be saturated at 416.78 °K, but you mentioned superheated...) at maximum flow of 222,654 Kg/hr and the density for saturated steam of 0.4625 m³/kg, I arrive at 102977 m³/hr, and your 30" pipe at inlet to the let-down is 0.456 m². Thus your velocity is 225,826 m/hr or 62.7 m/sec (205.7 ft/sec) which is slightly under the upper limit you mentioned, but I have no recommendation on that. It does seem somewhat roaring.

Any amount of superheat will by raising the temperature lower the density accordingly, and will add to the velocity. You report an initial temperature of 494.2 °K, so the velocity must increase by a factor of approximately 18% to 242.7, which may well exceed any known limits.

A1) Discuss the project with a local friendly valve distributor, and let that company quote for it.

A2)Yes, and possibly.

A3) Turndown is 222654/60000 [No calculator available here].

A4) as above, in all three cases

A5) Make the line size appropriate to the velocity in it not exceeding 10m/s.