Friday 16 December 2016

A Burst of Air From Our Super Air Nozzles Keeps Vacuum System Pipes Clean

An overseas textile company had many automated spinning machines to manufacture yarn from raw cotton and polyester fibers. They used a vacuum collection system to remove any floating fibers from within their spinning machines for safety reasons.  In this facility, they had three rows of ten spinning machines.  Above each row, a collection duct, ranging for 8” to 30” in diameter, would collect the fibers and transport them to a baghouse.  The difference in diameters was to keep the vacuum pressure the same in each spinning machine.  The machine that was the farthest from the baghouse had the smallest diameter pipe, and the machine that was closest to the vacuum system had the largest.  They needed to keep an optimum vacuum pressure inside each machine because too much would affect the production of the yarn and too little would allow the fibers to migrate into the production area.  The concern with fibers migrating in the production area was a fire hazard, a big safety issue.  In order to have each row of machines performing effectively, they needed to keep the static pressure as low as possible.

The issue that they had was the discarded fibers would gather and collect in the ductwork. Each machine had a 4” duct that would draw the fiber from the spinning machine into the bottom of the collection duct overhead.  The velocity profile inside the main line was being disrupted by each feed duct, as it allowed a “dead” spot for the fibers to gather.  As fibers would entangle with each other and become larger, the static pressure would increase.  This would cause the vacuum pressures to change inside the spinning machines, affecting production.  They would have to shut the row down, open the ductwork, and clean the entire piping system.  This was time consuming and costly as it stopped production.

The customer tried a homemade nozzle made of a copper tube. He flattened one end and placed it in the bottom of the ductwork just upstream of the problem area.  He triggered it intermittently, and after a while he noticed that he still had the fibers collecting in the pipes, but in different areas.  In knowing how the velocity profile is very sensitive in dust collection systems, any additional obstructions could cause the problem to change to another location within the system.  He contacted EXAIR to see if we could help him.
 Mr Johnball put on his engineering hat to help solve this issue. He suggested Exair's model 1104 Super Air Nozzles because it had enough force to reach the other side within the range of diameters.  The EXAIR Super Air Nozzles are very powerful and efficient nozzles.  It is designed to entrain the ambient air.  This gives it a powerful force without using a lot of compressed air.  My suggestion was to place them along the top of the collection pipe as Exair needed to keep the profile smooth along the bottom section of the pipe.  As a recommendation, He suggested for them to use an angled extraction port (not made by EXAIR).

It screws to the outside of the ductwork, and it has a 2” opening with a 45 degree angle (reference photo above).  They could aim the Super Air Nozzles at the “dead” spots to lift the fibers off the bottom; allowing the system to pull them toward the baghouse.  Without having to redo their entire collection system, they were able to cut an opening in the top of the duct and mount the Super Air Nozzles.  As an added benefit, the nozzles were not in the air stream; so, there was no additional static pressure in the system.  The customer was able to design a solenoid triggering system to have only one Super Air Nozzle to operate at one time.  It would start from the farthest point, and trigger one at a time toward the bag house.  With a short burst of air, it would keep the fibers in the air stream without affecting the operations of the spinning machines.  This customer was very happy as they were able to keep their operation running without a buildup of static pressure in the vacuum system and without allowing fibers to escape into the work area.

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