On/Off valve for syngas service

[DesertEagle01]

Hello,

I am in search for a manufacturer for On/Off valves for syngas service for a Syngas purging line.

Design conditions:

Pressure: 190bar (to atmosphere)
Temperature: -33°C/50°C
Size: DN50 or DN80
Housing material: Carbon steel

We have traces of catalyst in the purge gas which is a very hard material that can cause seat damages. We thought of a ball valve with a "Peak" ring to reach a longer service live. The valve shall be fully tight for a few years. Right now a globe valve is installed. It starts leaking after only opening and closing once.

Any help would be highly appreciated.

 

[Danlap]

Hi,

I presume syngas is very toxic gas with some nasty particulates. We also have similar application however less pressure (approx 80 bar) and higher temperature 200 degC
To guarantee fully tight, I would not rely on single valve (even with theoretically double seated design such as double expanding gate valve, etc)
and since there are particulates soft seated PEEK, PTFE, etc. also not recommended
Also ideally the cavity pocket and effective sealing area should not be "exposed" to this service. Globe valve you are using now is exposed to the service and particulates may stuck in between plug and seat

We use two gate valve through conduit with additional scrapper design (to scrap fouling built up on the wedge surface when valve is operated). And some standard gate valve with stem horizontally mounted. Some of these valves are sacrificial and replaced every 4 months in parallel with filter replacement or other maintenance activities.
Not really sure about special through conduit or slab gate valve availability on DN50 or DN80.
basically you can find any good manufacturer locally, but for your reference only the one that we use is Malbranque, KITZ and BSM

Overhauling or cleaning that small carbon steel valves might be not so economical, but if this is bigger valve (and exotic material) maybe extra steam nozzle purging on cavity or periodic cleaning can be one of the solution forward.
PS: we used to have DBB configuration, but the bleed was always clogged

Good luck, tight shut off for fouling application is always a challenge.

Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[LittleInch]

I agree, that is very severe service.

You won't get anyone to guarantee a valve if the duty is really 190 bar opening differential with "very hard material"

Your best bet is to look closely at some severe service wellhead choke valves and then add in a expanding gate slab gate valve as your true isolation valve once the flow has reduced to virtually nothing.

Then bank on replacing the trim in the choke valve ever few months.

How big are these hard bits?

Try these guys -

http://belvalves.com/products-services/surface-valves/surface-gate-valves/

High cost, but very good valves and will talk to you about your application.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

Are the plant process engineers aware of this catalyst breakthrough ? They ought to open up the reactor and see what's gone loose and call for repairs to eliminate this leakage - in the short term, it wont be just this purge valve having trouble with this catalyst fines.

Use a globe or choke valve with SiC or tungsten carbide hard faced trim to deal with this in the meanwhile.

 

[DesertEagle01]

Thanks for your replies.

Operations department informed me that the catalyst dust accumulates in the piping of the purge line (Valves are usually only opened once a year).
When the valve is opened, the accumulated dust is flushed with the gas stream to the atmosphere. It is almost impossible to remove the catalyst dust (Purge line is for emergency or plant shut down only) by a filter / separator.

There are two valves installed, both of which are currently of globe valve design with Stellite seats/plugs. Nevertheless, they start to leak after a few operations. The second valve was installed since the original one was leaking but it didn't really help.

We where thinking that a ball valve will give us a better sealing Performance than a globe valve.

 

[Danlap]

Is this similar with your dust?? the valve size is 8"

Even tough it is possible, I am a bit skeptical to use ball valve for two main reason:
- there is a micro gap between Ball and seat (that's why break to open/close torque is almost always bigger than run to close/open torque). The micro dust (not yet accumulated) as pictures above might be caught between this gap, and once operated it will scratch the sealing area. And this is prone for any common industrial hard facing such as TC, Stellite, etc.
- the size is DN 50 or DN 80 as you mentioned. Making it trunnion mounted with tight shut off requirement is a challenge, and making it with extra scrapping device would be an extra challenge. basically scrapper is an extra "relatively sharp tip" on the seat to remove the dust stuck on the ball surface.

Having said that, yes it is possible. But it would be really expensive and requires time to make one. Time = once these ball valves fail again, you will be depending on the manufacturer to provide similar design in a rush manner. Price is driven by the manufacturer.
Some good ball valve manufacturer for severe application ValvTechnology, MOGAS, etc.
IMHO, Plug valve would perform better in comparison with ball valve in terms of sealing ability for hard particles.

Success,
Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[LittleInch]

I think you really need some sort of expanding seat design where the seals are kept away from the sealing surface, so an expanding gate valve, plug valve or similar.

Any type of valve which involves a movement between sealing surfaces where the dust can reach will not seal after one or two operations.

Hence why I think you shouldn't bother and simply use some sort of controllable flow valve and a separate isolating valve.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[DesertEagle01]

@Danlap: That looks very similar to our catalyst dust! Was that valve leaking as well?

I will contact above mentioned suppliers to get some quotes as well as their idea on the issue. Is there anything like "seat cleaning" (e.g. with pressurized air) before the valve closes to "blow away" any hard paricles.

@LittleInch: Is there a supplier you could recommend?

Below a Picture of the damage we found last year on the plug.

BR

 

[Danlap]

Hi DE01,

Yes, that double expanding gate valve was leaking. Now we are using through conduit slab gate valve, with better performance
Related to your "seat cleaning" question. For syngas application, there is always a debate not to introduce extra leakage path which in this case extra nozzle to blast the air. But I leave this up to you and process safety to judge
For that reason: we don't use it for sygnas application, even-though I love to try it. But we use that for catalyst cracking valve, and works well. Snip drawing as below (my excuse, I will delete this photo if there is disclaimer from manufacturer).
These supplier are FCC (fluid catalytic cracking) specialist: TapcoEnpro; Zimmerman Jansen; IMI remosa. Hopefully someone can make a smaller version for you

the one LittleInch referring to is BEL valves. they are really good as well

Regards,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[georgeverghese]

Believe Mokveld make control valves for erosive service too for high pressure applications - here the trim is not exposed directly to the flowing stream. They cost somewhat more than other makes.
In the other hand, if you intend to stay with throttling valves, select the valve for more than 70% open at the required flow.
In addition, you could further reduce the erosion by installing another more rugged device in parallel to take say 80% of the available dp and leave the remaining 20% for the CV. This device would be one or more thick plate restriction orifices located upstream (or downstream) of the CV. These ROs' would also have be made out of some erosion resistant material. Replacing these ROs' would probably be much cheaper than replacing seat and trim (at the least) on the CV.