Please use shot peening pipes instead of smooth conveying pipe!

shot-peening pipes can decrease heat generation.

Dense phase pneumatic conveying process can effecrtively decrease angel hair too. Because it adopt lower velocity relative to dilute phase process.

chenjun-nj@163.com ■

Certain types of plastic materials when pneumatically conveyed in smooth pipe tend to deposit material on the inside wall of the pipe. These mini-depositions tend to meld together and are randomly released into the conveying stream. The nature of the released material varies between short threads and long streamers. QC issues occur when downstream gravity flow paths are blocked by agglomerated threads / streamers.

It is well known that treating (roughening) of the pipe wall is effective in reducing streamer generation. There are numerous treatment methods available but the most cost-effective solution has proven to be directional shot peening.

Shot peening is a cold working process in which the inside surface of the pipe is bombarded with a spherical media called shot. For conveying pipe applications a special nozzle using high pressure air is forwarded through each section of pipe. A dimpled surface is created that changes the pellet-to-wall impingement mechanism from sliding to impingement. In this way streamers can be effectively eliminated but be aware that the level of fines will likely increase.

Regards,

Dennis Hauch ■

Treated pipe and elutration are acceptable starts. I would suggest that you also look at blower speed, air volume and line size. If you do not have a cooler and you are running at high velocitys, you will continue to have fines and streamer problems even after you treat the pipe.

If the product is virgin, treating the pipe will help. If the product has additives that will destroy the treatment. Some compounded Polymers will not cause streamers because they are self cleaning the line. If you are conveying with 50c-65c air (120f to 200f) you will possibly coat even treated pipe. Also look at velocity and try to stay below 6000 fpm terminal. It migh help to step the pipe at the end.

There are other variables based on copolymer and homopolymer materials.

You should have a study done to identfy all the problems so when you do spend capitol, you do so wisely.

Belsco Services, Inc.

www.belscoservices.com

Report ■

Dear kalpesh,

Since some years we are using a typical kind of pneumatical transport at low air velocity. If you are investigating a new installation this application might be of your interrest.

At this low air velocity the behavior is a bit different from high velocity transports. Because of air viscosity a laminar air sheet is formated and almost no contact between the material and pipes will occur. The velocity of the material is the same velocity as the air velocity and thermic influences are almost 0. We even use this method to transport milk powders with increased amount of fat which is extremely sensitive to temperature influences.

Technical specs:

Starting velocity of the system is about 2-3 m/s at 2-2,5 bars overpressure, end velocity is about 6-9 m/s at 0 bars overpressure. Loading degree is about 100-300 kg material / kg air. The amount of air needed can be produced by a normal 6 bar compressor and pipe dimensions are less then traditional transport systems, 2 bars effective air consumption or . Maintenance costs are in your case about 25-50% related to traditional systems. Obstructions in the pipes, caused for example by power drops, are automatically pulled back to the sending vessel, prohibiyting the necessity to take apart the piping.

If this is of your interest, please contact me. ■