Using three principal factors to customize pneumatic conveying systems
Material transfer is an integral part of any operation. When increased production demands and new product lines challenge a processing line, those charged with optimizing production must evaluate an array of factors when determining the best method for moving chemical ingredients.
To eliminate wasted efforts in production, manufacturers are moving away from conventional methods such as bucket elevators and hoists that can present a variety of challenges in the processing plant, and into more automated processes using pneumatic conveying technology to move material.
Pneumatic conveying systems are customized based on three principal factors primary goal, material characteristics and delivery speed.
Edward Dodge, Operations Manager, at Helena Industries’ Cordele, Georgia plant agrees. “It all depends on the area or what we are doing or the type of material we’re using.”
The Georgia plant uses a broad range of process technologies to manufacture, formulate, and packages herbicides, fungicides, and insecticides for its clients of well known brand products. “We had a unit that started to get a lot of business,” says Dodge, “and that is why we started looking at different transfer systems.”
Perhaps the most important aspect of choosing a vacuum transfer is determining the primary goal processors wish to attain. These systems have the ability to increase productivity, solve safety and hygiene problems, reduce costs, add flexibility to line, eliminate product contamination and a host of other issues.
Helena Industries strongly protects its workers and has a comprehensive plan to improve ergonomics in its plants. When increased demand turned up the notch on production, the company’s primary goal was to eradicate an ergonomic issue by removing the need for workers to dump 20-40 drums containing powder chemicals, that weighed up to 225 pounds each, from a raised platform.
Although the job required a single operator, Helena staffed it with two people. “We haven’t had any injuries, but it was always a potential and we have tried to go through the plant and kill any potential we have with ergonomics,” stresses Dodge.
“We tried a bucket elevator and it was terrible because it created a lot of dust in the air and we still had some ergonomic issues with over exertion when dumping the product into the elevator.”
In attempt to yield desired results from the bucket elevator, several speeds and discharges were tested and the unit was eventually moved to the other side of the tank to modify the angle of repose.
When the drawbacks for this application proved insurmountable, Dodge considered a hoist system but that would have required operators to do some drum handling which would have made the process significantly slower than their existing method.
After bucket elevators and hoist systems failed to provide a solution, Dodge says “we finally threw in the towel because it was worse than what we had to start out with,” and he contacted VAC-U-MAX, one of the few suppliers who routinely designs and builds custom pneumatic conveying solutions.
“They had the best understanding of what I wanted to do,” he says. “I didn’t have to spend a half hour trying to explain why I was transferring and how I was transferring it—they were well educated in that area.”
An understanding of material characteristics is essential when designing a vacuum transfer system. Commonly, there are several product grades within the same product group and those forms may be free flowing, sluggish or non-free flowing. For instance, one grade of Zinc Oxide may have the consistency of talc while another is more cohesive and may stick to the sides of conveying tubes.
When cohesive materials that are prone to stick inside the system are used, solutions such as a high polish finish applied to the interior may be appropriate to reduce the possibility of packing inside the conveying line.
Since vacuum transfer systems pull material through the tubes vs. pushing the material, they are suitable for most materials and can be customized regardless of the characteristic.
“That is what we like about those units, they are flexible. If you want speed you can build up the system, if you want to eliminate a hazard you are able to do that and not have timing be an issue,” says Dodge.
The size of the vacuum transfer system depends upon the desired speed at which product is transferred from one place to another as well as the distance between two transfer points.
“If we wanted we could have purchased a much larger unit if speed was of the essence, but it wasn’t a timing issue we were looking to solve, so we chose not to do that with this unit,” he says.
To move several hundred pounds of material in 30 minutes, an 8×16 unit with a cartridge filter was utilized to transfer the claylike material up a level into a volumetric feeder. Another 8×16 unit with a unifilter was also added to a separate line that pulled granular material from awkward shaped drums weighing aver 200 pounds each, up into a liquid mixing tank.
Although the time to transfer the products stayed relatively the same with the new units, the jobs went from requiring two people to a single operator. “We weren’t looking to cut any people, but we did save some money by it. We actually paid for that first piece of equipment in one year.”
When improved production capacity is the goal, vacuum systems are designed to meet the need. For high volume products systems can even be designed to pneumatically load material directly from silos at an even greater rate of speed.
Many manufacturers have additional concerns that also need to be addressed outside of the primary goal. Helena Industries, for instance, was concerned about clean up between different runs on the line and wanted to be sure that the equipment could be taken apart easily and put back together again without sharing any contamination.
“We don’t need to send a maintenance man down to take it apart. Our operators who run the equipment easily take it apart and clean it and reassemble it and you don’t need a special tool,” he says.
There is virtually no maintenance or cleaning necessary in the pneumatic conveying systems because they have few moving parts. “As far as reliability we have had the unit for about 18 months now and the only thing we ever do to it is check and clean the filter. “
Dodge is also pleased with what he calls bonuses from the vacuum system such as minimizing environmental dust exposure and improved housekeeping because the drums no longer need to be inverted.
“Vac-U-Max supplied all the drawing so we don’t have to do them ourselves. It was one of those rare instances that when you spec out something over the phone and email, bring it into the plant and have look like you thought it was going to and install and work like they said it would,” exclaims Dodge, “it doesn’t get any better than that.”