Proper Valve for a Organic Solid Charge Chute

[LucayaLive]

We have several applications where charge solids into vessels via 8" and 6" diameter charge chutes. These vessels may contain organic solids. We have tried knife (gate) valves, qurter turn ball valves and butterfly valves and each failed for a variety of reasons:

Knife Valves get solids stuck on gate and between seats, preventing a good seal. The butterfly valve blocks if the material is too lumpy. The ball valves also get solids stuck to it's surfaces, which score the seals causing leaks.

Any solutions out there that can help?

 

[JimCasey]

Well, there are "rotary valves" also called airlocks.

a 6-8-or 10 vaned rotor spins inside a housing. The rotor is driven by a gearmotor at up to around 20 rpm. The solods drop into the rotating wedge-shaped chambers, the rotor carries them around, and they fall out of the bottom

THis is almost exactly the same principle as a scaled-down revolving door.

Profiling of the rotor tips helps to tailor the valve for abrasive, or gummy, or other material properties. Materials of the rotor an housing can be selected for compatibility.

I am familiar with Premier Pneumatics who make such a valve. I will follow with a post and a link.

 

[JimCasey]

Here's a link. This is their quick-clean valve so you can open it up and clean it if it gets fouled with sticky product.

http://www.premierpneumatics.com/alockQC.htm

 

[LucayaLive]

JimCasey,

Thank you for your response. I should have been more specific. The valve is needed to hold pressure on the reactor once the charge is completed.

I don't think rotary valves would hold pressure (they are typically used to maintain inert atmosphere in charging vessel, are they not?).

I need something that will hold 40 - 50 PSIG once I close it after charging.

 

[moltenmetal]

How about a teflon-lined ductile iron full port plug valve? Nice big hole to drop solids through, and teflon so there's reduced risk of things sticking and hanging up on the valve. On the downside, the rotational torque on these is large due to the large seating surface. Consider putting an air operator on it. Xomox or Durco (Flowserve) are the two big brands.

Or a ball valve with hard (metal) seats. No organic is THAT hard...

Or a resilient seated butterfly valve, but put a Grizzly screen ahead of the addition hopper to get rid of the lumps. You won't scratch a rubber seat...

There are knife gates where the knife goes straight through the body leaving no cavity to stop the knife from being completely inserted, but I doubt you'll find one of these good for tight sealing.

Or you could put a chute or funnel on the inlet, so the solids fall straight through the hole of an ordinary full-port ball valve and don't get a chance to hang up on the ball and score the seats.

 

[JimCasey]

You're mostly right about the rotary airlock valves. They are rated at up to 50 psi differential, but I would not expect them to be tight. You can feed solids thru them into an up-to 50 psi system.

Moltenmetal has some really good tips. the rubber-lined butterfly valve with the rubber-coated vane is a good choice for sticky crumbs. The rotating vane will fracture clumps, and the flexing rubber will break loose any crusts much like the old pneumatic deicer boots on airplanes. FDA-approved materials are just a check box on the order sheet...not tough to get. Tyco/Keystone and Bray are among the manufacturers who make such valves.