KOH dosing system

[IPGBen]

Hi,

I'm looking for an (automatic) dosingsystem to add KOH pellets into a vessel.
Amount around 25 or 50 kg (so 2 bags)each time

Now we add this through a funnel. this means we have to open the vessel when adding the KOH.

Is there anybody who has experience with this kind of equipment?

Grtz
Ben

 

[DeltaCascade]

Not too familiar with this but:
- have you considered buying in liquid and using a metering pump (eg" MiltonRoy/LMI diaphgram pump)? Your KOH would cost more as it would come diluted with water in a 1 m3 tote tank or have bulk delivery, or such, but easy to handle.
- perhaps your KOH Pellet supplier or manufacturer has suggestions.
- try "solids handling" in the Chemical Engineering Journal Buyers Guide, or other such index. There's many manufacturer's listed there.
- try a keywork search on this site?
Hopefully someone with direct experience will reply.
Good luck.

 

[IPGBen]

Hello DeltaCascade,

thanks for your thoughts. To answer your questions:
The option to use disolved KOH in water is considered but is no option for this material.

I will however see if there are any manufacturers which will come up with solutions.

Thanks and I hope to hear from others with experiences.

Grtz
Ben.

 

[bchoate]

Bill Choate

Only a little information has been given to us so far. This approach will encounter more than a few problems. How often is KOH added to the vessel. If it is infrequent, automating addition is questionable from economic view. A system that can work is described as follows. It assumes that your vessel can be configured appropriately.

The most important issue to deal with is the fact that KOH pellets absorb water from wherever it is available. Keeping the system anhydrous (if you want pellets to flow)is key.

Why is aqueous KOH solution not an option? Does the vessel not contain water? Would it be possible to dissolve the KOH in something like methanol.

A system to deliver KOH consists of:
bulk KOH pellet storage
a volumetric shot tank
a reactor recyle line
actuated control valves
nitrogen blanketing

The bulk KOH bin must be kept dry with a nitrogen purge.
This bin should be a mass flow bin with a steep cone lined with ultra high molecular weight polyethylene (UHMWPE). A knife or iris valve can be used to control flow out of the bin. The bin should have a purgeable port through which to add KOH to the bin.
The bin outlet (3" min.) should connect to a small vessel (cone bottom) which will recieve the charge of KOH and measure it. There needs to be someway to measure the KOH charged to the vessel and to keep from overfilling the vessel (load cells, point level switch, etc.) The small vessel connects to the reactor, etc. through an actuated valve.
Operation is as follows:
Actuated valve on reactor is closed. Actuated valve beneath knife valve is closed as is knife valve. Actuated valves on reactor liquid recycle and purge gas are closed. Actuated valve on vapor balance line between shot tank and reactor is closed.
Fill cycle starts:
Actuated valve beneath knife valve opens
knife valve opens - shot tank begins to fill
vapor balance actuated valve opens
level switch closes knife valve
actuated valve beneath knife closes after delay
actuated valve between shot tank and vessel opens and begins to dump KOH pellets into the vessel
liquid recycle line actuated valve opens and begins to wash out shot tank
on time - liquid line actuated valve closes and nitrogen line opens to dry out shot tank
nitrogen line actuated valve closes
shot tank bottom actuated valve closes
vapor balance actuated valve closes

This scheme will add KOH by weight and time to the vessel. If there is a solvent that can be used for the KOH, addition will be much easier.
Bill Choate