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Help troubleshooting Pump for ball mill sin exchange for FREE CHOCOLATE!

H

Hallotp

Plastic
Joined
Jun 25, 2019
Hello to all on the forum

This may not be the correct place to post this, so if anyone has advice on a better location, I would really appreciate the help.

My problem is with the ball mill that grinds chocolate from the roasted beans. There is a pump at the base that cycles the chocolate through and returns it to a spout at the top to reincorporate with the rest. The pump should be activated until the beans and sugar have ground up enough to flow. At this stage its basically a viscous suspension of melted fat and small solids like sugar.

The problem is that even with the pump off a small but continuous trickle of chocolate comes out of the spout. My first thought was that the shaft of the pump was still turning through some fault, either electrical or mechanical however I have verified several times that it is not turning even in the slightest. The fact that the chocolate is still passing through and going straight up a pipe WELL ABOVE th level of the chocolate in the mill is something that I cant get my head around. Im attaching photos to help, but if anyone knows what this is, I'll gladly send you out some chocolate.
Thanks!0-1.jpgIMG_3429.jpg0.jpg0-2.jpg
 
Total shot in the dark, but maybe a clog or one of the braided lines collapsed inside and while the pump is pumping everything flows fine but when the pump shuts off the residual pressure behind the clog keeps oozing?
 
If there was air mixed in with the melt it would tend to expand at the first opportunity and force the melt out of the spout. I see what appears to be a pneumatic operated ball valve below the spout. It is the box shaped gadget with the red hat in the second picture. Is the valve closing when the pump cycle is complete?

The return pipe also has a water or steam jacket. Is there a steam leak in the jacket that may be forcing the melt out?

I would also expect that there would be some process which blows out and empties the return pipe at the end of the work shift to prepare the grinder for cleaning. The problem may be that the PLC controller is confused and is instructing the grinder to clear the pipe.
 
I'm inclined to hitch my wagon to Robert's guesses above. Have you noted how long the undesired flow persists after the pump is shut off? If it is reasonably finite and consistent I would think that something may be purging the line with some kind of pneumatic pressure.

It may even be leftover pressure in the system. 80 psi is about 5.5 atm, so in order to equalize after everything is shut off, 5x the volume of air on the "process" side of the valve will need to go somewhere. Path of least resistance is spitting a little extra chocolate out of the spout. In this case it would taper off very slowly and probably never completely purge the line. You might notice significant burbling on start-up of the next batch.
 
My guess is the ball mill is actually forcing the choclate through the pump. How about a pic inside the ball mill next time you get it cleaned up.
 
gbent said:
My guess is the ball mill is actually forcing the choclate through the pump. How about a pic inside the ball mill next time you get it cleaned up.
Click to expand...

My thinking as well. The rotation of the mill is causing hydrodynamic pressure of the viscous fluid, causing it to be pumped up the return pipe.
 
gbent said:
My guess is the ball mill is actually forcing the choclate through the pump. How about a pic inside the ball mill next time you get it cleaned up.
Click to expand...

That was my first thought, + any air pockets in the system would compress and ''squeeze'' the choccy out of the pipe after the pump is off.

Please, no nuts in my choccy, (the bits get caught under my denture plate) raisins are good, cherries even better :)
 
Seems easy enough to test the two prevailing hypotheses:

1. If it's a positive displacement pump, it would not allow fluid to be forced through it without shaft rotation. Otherwise, the mill itself could be pushing chocolate around.

2. If the flow tapers off and eventually stops, it could be pressurized air pockets expanding after shutoff.

Keep us updated, I'm interested to hear about what you end up finding. No need for sweets, I just think it's an interesting puzzle.
 
I don't see anything there that I recognize as a ball mill. I don't see how it could grind or produce any flow. Could you give more details on this
 
The chocolate ball mill machines, judging from a duckduckgo search all seem to be made in Europe or Asia.

The Packint mill is made in Italy. Their website is :About Us | PACKINT

This is a example of a major manufacturer's product line: Chocolate Processing - Royal Duyvis Wiener B.V.


The OP's grinder is a small machine. The grinder uses a high pressure pump for the viscous melt. It appears to be a gear pump. The small machines have a three way ball valve. The valve allows recirculation of the melt during the grind phase and then directs the melt to a holding tank using a transfer line when it is time to empty the grinder. The 3 way valve is placed at the base of the grinder on other designs to allow the vat and return pipe to be emptied.

The OP's grinder has the valve at the top of the vat. The return pipe continues past the spout and the three way valve to a higher elevation for the transfer line. This feature is cut off from the top of the picture.

The transfer line is acting as a stand pipe and would cause the unintended spout flow if the valve leaks.

The ball mill design consists of a central vertical shaft driven by a motor -speed reducer set. The vertical shaft has a number of radial arms extending outward. At the end of each arm there is a pocket which holds one grinding ball. The ball rolling against the side of the vat grinds the chocolate and sugar to 30 micron size particles. The taste of the chocolate is strongly dependent on the grinding operation. This grinding process is followed by a tempering process which cools the liquid and forms crystals. This insures that the chocolate will become a stable solid.
 
Last edited:
How about this. The chocolate is very viscous and when you turn the pump off it takes a while for it to run out of the spout. This isn't water.
 
Keyepitts said:
OP's in California; the machine is missing its Prop65 warning label, that's the problem. #needmorelawyers.
Click to expand...
I just bid on some collets on the bay and they list a Prop65 warning, and they're in Iowa! I remembered reading about it here (I'm in Switzerland). They we're probably made in the 60s.
 
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