Decreasing Unload times for Pneumatics

If you think you've mastered bulk tankers, you are setting yourself up for trouble.....

 

Lol what else is there to know?

 

Over here in Australia our tanks have working pressure of 175kpa and a test pressure 260kpa.
I agree the secret to fast unload times for cementishous products is tank pressure and air supply to the tank through the aerators fluidising the product for exit of the product valve.
minimum amout of purge/boost or line pressure up the pipe to help the product on its way. This amount varies depending on length of push, 10 feet no purge 200 feet up 17 stories high full purge.
A short hose from tank to silo pipe.
I usually have a trade off between tank pressure and purge governed by the tanks safety pressure relief valve Which starts leaking and making noise at around 150kpa
if the silo fill pipes are in good order and the silo doesn't look like its 100years old there will be no problems as long as the gauge is watched for pressure drop signalling danger for the fillter/s on the silo caused by an empty compartment.
The pressure in the tank registed on the gauge is just that the pressure in the tank not the pressure in the silo, there is more pressure in the product hose and silo pipe than the tank.

Have I had silo pipes rupture? Yes and on inspection of the pipe it was never a concern about pressure more that the product as worn the pipe thin over a period of time. Best one was a section 10 inches long split and the pipe was paper thin in this section

 

Look, there's no point in being a big swinging #### about this. It's not rocket science. You follow the instructions printed on the side of the tank. If you can't read, then try to make sense of the pictures that accompany the instructions. Once you get the basics, like any halfway decent monkey, you start fooling around with the valves and see what works better.

Some things work with some tanks. Some things work with some products. Some things work with some products inside some tanks.

To the person who asked about sand, the short answer is no. The reason is sand is so heavy that it doesn't need any tank pressure to blow it into the product pipe. It naturally falls into the air stream you have going in there. Also, with sand, you can only let a little fall into the product pipe at a time, or it will start clogging up. It makes little sand dunes inside your product pipe unless you have almost all your pressure used to adios it to wherever you are pumping it.

So, with that in mind, for sand my prescription would be - product valve wide open. Hopper valve partially open. One hopper at a time. If tank pressure starts to build, open blow down valve for a few seconds to get pressure back down to a fairly low level, maybe 3 to 5 to 8 psi (depending on how your tank handles sand). Keep pumping. (again, depending on how your tank handles) No more than 10 psi or the sand will start making little sand dunes in the product pipe and you are looking to get clogged up.

Depending on what you got and your tank and what you are pumping into, you are looking at 2 hours plus for a full tanker.

Does that sound about right, you sand jockeys?

Keep in mind, I have never done fracsand, only calcium aluminate and bottomash/bedash. I would be interested in learning how fracsand pumps out of a trailer and hear the ins and outs of your specialization. Do you guys pump it into a pig on a jobsite or something, or up into a silo, or where?

EDIT: one quick note about why I empty the last hopper first (personal preference). If I have to reverse pump and suck product back into a hopper, the last one in line is the easiest both in terms of a clog in a silo and a clog somewhere upstream of the empty hopper. In a reverse pump, your air pressure will be flowing from first to last, so you won't have to fight both the clog and the full amount of air pressure you are creating by reverse pumping. Just my reasoning on why I do it that way. I'd be interested in other people's reasoning and hearing about their troubleshooting tips. I'm always looking to find a better way to skin this job...

 

One of the key factors in unloading time is plant facilities. We haul mostly cement and flyash on doubles, usually 27 tons to the load. Some of the more modern and well maintained plants are a pleasure to unload...25 minutes and you're gone.
Some of the older plants with high silos, long hose runs, clogged unload tubes, and poor bag houses might take a couple of hours. There's one company that we call Clog City and we always make sure to take an extra sandwich and something to read.
As I general rule I figure an hour average, gate to gate. That allows for set up, hookup, pressurizing, unloading, and takedown.
We get paid by the hour and the company is happy with an hour average. They're happier if we can shorten the times, too.

 

I just got a set of J&Ls and at first I didn't want them because they looked old as hell but they unloaded in about 18 minutes. Type 2 cement. I couldn't believe it. I actually called our mechanic to ask him why and he said it was because they just installed fluffers. So, it can be done. I get paid per load so this is a major plus.

 

Anybody know anything about unloading sugar?

 

Wot?!

Park truck and trailer close to silo.

Get hose on both ends. Ideally the tanker...

Attach other hose that feeds air to tanker.

Grab 5 gallon bucket, fill with water for leaks. You will know then when you see one. Pour on it.

Make sure everything is tight and closed.

Add air until 12 pounds on main tank gauge.

Open rear pot a little bit. Watch discharge hose snake on ground as product begins to move.

Keep pot open just enough not to lose main tank pressure at 12 pounds.

Keep eye on hose. And stand on it too. You will feel the product moving in your feet. Just like a pulse. Now if you don't have a pulse and it's a trickle or worse nothing close off product line and feed max air into discharge pipe.

If your trucks starts to cough close all pots and open discharge to the max. Grab mallet and bang on the silo pipe.

If everything is in balance, cement should be out of there no longer than 1 hour. Give or take.

I never have hauled delicate stuff or melty stuff. So I am a bit of a anvil when it comes to bulk tanker work.

When first pot is empty (After it sings to you while you tap the pot with mallet (Rubber, never metal.) you will feel hollow inside.

Close first pot, open second. Achieve balance holding 12 pounds while snaking discharge hose.

empty that pot, close then open last pot. (OR third, forth etc)

empty that one. Your tanker will really be singing at this point.

Stand on your gauges make sure you are at 12 until last pot empty then close off discharge. Kill the feed air.

Walk around and CHECK THE DUMP Pipe outlet area for 5 feet and beyond to make sure no souls are hanging about. Blow down tanker.

Go get papers. Put away hose.

One last thing. This lesson is worth your life....

Never. Whatever you do, or are told to do... never.... go top of tanker when there is air in it. ESPECIALLY never undo the hatch and it's bolts. The third or fourth bolt you do will be the last thing you ever do in this life as your dead body is fired downrange and the whole yard filled with product a foot deep.

 

The fastest way to unload into a pig that I’ve found is to:

1. Get tank pressure 10-12 psi
2. Open line valve to full
3. Open product valve full
4. Verify product is moving
5. Close line valve all the way off.
6. When first pod starts dropping (you can hear the vibrators), close product valve.
7. Open line valve to full and open next pod and repeat 4-6.

I unload into pigs all the time and am rarely at the job site longer than 30-45 minutes total from the time I pull into the drive way until the time I leave.

For any newby reading this, please note this process is ONLY for pigs. You turn the line pressure valve all the way off going into a silo and you’re gonna plug. Reason is you need that line pressure to push the product up, and usually pretty high up and often a good distance.

It works on pigs because you’re not pushing product very far and and not more than 10-12 foot high at the most.

 

The "expert" at my former company said to get the hose to the point where it was jumpin'.
Had the opportunity to use a new clear hose on a load. Got the product to move smooth and fast.
No hose jumpin'. 50K+ of stuff like baby powder.
Fastest onload (railcar to trailer/pup, with truck mounted air pump supplying) I ever did.