On Off valve used on adsorption tower

[fifaln]

Dear expert,
I have the following question on which need your help.

Background:
The adsorption towers are used for the SYNGAS (hydrogen) purification before it goes to COLD BOX. The licenser is Linde Engineering. My interest is in “the valves type selection used for the adsorption sequence control".

Before, I normally used the “rising stem" type ball valve (eg, Orbit of Cameron), since there is no friction between the seat and ball when it is opened/closed.

But this time Licensor required to ramp open/close the valves and bi-directional shut-off tightness. To satisfy this requirement, a bi-directional sealed valve with positioner is required, and obviously, the “Orbit” valve is not applicable.

In adsorption stage, the design temperature and pressure is -70 deg C and 3.7MPaA; in regeneration stage, it is 280 deg C and 0.9MPaA.

Question:
1. Is the triple offset butterfly valve applicable for the process described above? Since the big temperature difference between the two sides of the disc (during the valve closed, one side may -50 deg C, and the other side may 200 deg C), I wonder whether the valve can work properly.
2. Does anyone have such successful experience, using the triple offsets butterfly valve under the same condition? What is the brand name of the valve?

Thanks for your help.

 

[Montemayor]

fifaln:

I am quite surprised how easily you dispel the application of the Orbit valve in high pressure, fixed-bed, adsorption units (presumably using Molecular Sieves). After 49 years of designing and working with adsorption beds I have found no better block valve than the Orbit in this application. It is my opinion that it is the valve of choice in the field of fixed bed adsorption systems. The only reason it would not be employed would be because of its relatively higher price – and right fully so, considering the tight and special process specifications it has to fulfill.

You state: “To satisfy this requirement, a bi-directional sealed valve with positioner is required, and obviously, the "Orbit" valve is not applicable.” Could you please explain what is “obvious” about Orbit valves not being applicable? The Orbit is a ball valve and, therefore, perfectly bi-directional. The Orbit has probably more hours of service in adsorber operations (and under more severe pressure and temperature conditions that you cite) than any other single valve. Please correct me if I am wrong – anybody. I would never try to apply a butterfly valve to such a critical application as a fixed bed adsorber - whether offset or not. It just isn’t the design for the application. In my opinion, it will never withstand the consistent temperature and leakage constraints imposed on it.

What does the licensor, Linde Engineering, have to say about the application? It is their design that is susceptible to any leakage or failure occurring in the adsorber valve operation. I am sure that they will want to have a say-so about the quality and performance of such valves.

 

[fifaln]

Montemayor:

Thank you very much for your reply.

The Orbit valve is "rising stem" type which have an " orbit" in the stem to guide the valve rotate. And the sealing face of the ball and seat is only in one side, that's why there is a flow direction "arrow" on the valve body.

Also, I'v consulted with Orbit people, they said Orbit valve can't be worked with a positioner because of the "orbit in the stem".

Linde Engineer didn't provide any recommendation on the valve selection,but only said the positioner and bi-directional tightness are required.

I'v consulted in some other projects that some of them used the triple offset butterfly valve. To be honest,I also really doubt the reliability of the butterfly valve.

 

[JLSeagull]

Orbit valves have a "preferred pressure end" thus are not exactly bi-directional. Shutoff is better from one side than from the other. Contact Orbit for seat tightness with pressure on the "other" end. Perhaps another manufacturer such as Argus is acceptable. Request Linde, the licensor, to recommend a suitable valve.

 

[fifaln]

JL Seagull and all,

I'v asked Orbit for the tightness of the other side. The answer is that it depends on the force acted on the actuator, though they don't recommend to try that.

But how to deal with the positioner requirement?
Linde only gave their requirement, but would not tell me which valve type should be suitable.

I also checked with my friends and knew that butterfly valve were used in a project but the process condition is different (temp:-10~105deg C,max press:28 bar).

In my project, there are two adsorber(PSA),the process condition is: temp:-70~280 degC, max press:37 bar.

It's not a high pressure and temperature, I'm not sure whether butterfly is applicable?

 

[bcd]

I suggest contacting Mapag valve in Germany. Linde owned them up to a few months ago and I'm sure their engineers have designed an offset butterfly valve for this application. It will give you the bi-directional shut-off and quarter turn operation that is easy to set-up with a positioner. Mapag was essentially Linde's private valve company handling all their special needs.

bcd

 

[dcasto]

here is new valve, designed by ex orbit guys

http://hemiwedgevalve.com/public/pag12.aspx