Pneumatic Systems

1. The fan is operating at its rated speed and cfm.

2. There is no upstream valve. There is a vortex tube though, and it is through this that the air is taken up through the fan suction.

3. There is no obstruction in the feed pipe, but there has been reports that there is a slight build-up of solids within the feed pipe to the cyclone.

Pl comment.

Unblock the pipe.

Oke. Will try . Tq.

Check also that the solids loading in the feed to the cyclone does not exceed the design maximum criterion provided when the unit was built.

Thank you. Just for info, the system loading has been designed backwards. That is . the fan cfm has been calculated with pipe and efficiency loss parameters included so that the maximum feed throughput is catered for.

Thank you. Please note the system in question :

Raw Material under suction -> suction vertical ducting -> suction horizontal ducting -> Separating Cyclone -> raw material + air swirl around the cyclone -> heavier raw material drops to the cyclone base -> Raw material expelled via the air lock -> to open hopper.

Air travels up into a vortex tube -> tube leads to the suction pipe of the Cyclone Suction Fan -> air is expelled from the Fan to the atmosphere.

The expelled air should be clean air, but now contains fibre fines. The air lock is air tight.

Would your solution suit the above issue ?

I believe that it would. I feel that the fines are building up on the inner "lid" of the Cyclone (held by static forces triggered from the friction) and are breaking loose and being captured in the relatively high velocity fan intake.

My recommendation of the 10% larger pipe could, and probably should be more like 25-50% larger diameter to be sure that the velocity is well below transport speed.

The rest of my original post explains the further operating parameters.

Noted and thank you. Will look into increasing the diameter ( 25 - 50% of fan suction intake diameter) and length ( 35 - 40% of cyclone height) of the vortex tube within the cyclone as suggested.

FINES are always a problem. I once worked on a system where the Cyclone supplier told the customer that- due to the fines in the process- their system would only be 50% efficient in product removal. My customer (who had hired me AFTER they bought the cyclone) had missed that statement.

My solution was to use a positive feed INTO the cyclone and to change to a negative extraction FROM the cyclone- providing for a point of ZERO PRESSURE inside the cyclone- and then to take the cyclone exhaust to a bag house that was to support a dust collection process that was part of the overall system. We just had the bag house make a little larger to support the added air flow. WE got over 80% performance from the cyclone and the bag house was able to support the added material load with no trouble.

Is the product still meeting the original specification in terms of particle size? If there has been an increase in the proportion of particles below 10-15µ within your product, those particles may not have enough mass to be effectively separated by the cyclone.

Two solutions available. Easy solution, bring the product back to specification. More difficult solution, install a new hopper with a filter and back-jet cleaner between the fan and the cyclone exhaust fan. Periodically empty any build up up product fines accumulated in the filter hopper back into the product stream after the cyclone outlet.

Thank you for the input. Unfortunately, for my application it is not possible to install a filter on line. Also the system has been designed to cope with the entire mass. based on the inputs, I may need to get the feed line checked and cleaned periodically, also to improve upon the cfm to cater for the finer mass particles.