Blower Fill rate using a ventury

Below are the latest pictures of a ventury I am now using. I am getting a fill rate of 960 lbs. per hour with this ventury. The rate of fill now appears to be limited to the amount of air being pushed through the pipe. If too many pellets are put into the fill pipe they feed into the pipe slowly as the pellets in the blower pipe are gone.

The next thing I plan to do is to add a second saw dust blower into the system. This should double the amount of air feeding pellets and hopefully increase the rate pellets can be fed into the silo.

The air is flowing through the 4" "T" fitting and on up to the silo. The vertical tube is a 3" pipe that extends down into the air flowing through the 4" pipe.

The end of the 3" pipe is cut at a taper that allows pellets to drop into the air flowing through the 4" pipe. The shape of the taper on the three inch pipe is critical. Too much blockage in the 4 inch pipe and not enough air gets around the 3 inch pipe to carry the pellets to the silo. Notice that air can flow around and under the 3 inch pipe.

Because the 3" pipe extends down into the air flow it acts as a restriction in the 4" pipe causing an increase in pressure. After the air goes around the three inch pipe it once again is in an unrestricted 4" pipe which causes a drop in air pressure. This makes a small suction on the three inch pipe which also helps pellets enter the air flow. As more and more pellets enter the 4 inch pipe there is more and more weight in the 4 inch pipe that has to be pushed up the pipe. If there is too much weight in the 4 inch pipe back pressure builds up to the point that the pellets in the 3 inch pipe stop dropping into the 4 inch pipe until the weight is reduced. A steady flow of pellets feeds faster than the stop and go method created when there is too much weight in the 4 inch pipe.

I am using a funnel with around a 1 3/4 inch outlet when dropping pellets into the 3 inch pipe. Right now using a 1HP 220 volt 11.5 amp shop sawdust collector I can unload around 960 pounds per hour.

I have a friend with another shop saw dust blower that is also 1 HP. I am going to hook both machines to the 4 inch pipe using a "Y" fitting to see if I can increase to amount of pellets I can move.

If there are any engineers out there that would like to wade in here I would like to hear from them.