Vacuum conveyor helps get chemical process flowing

International Specialty Products (ISP), an $800-million company that has matured into a global leader in specialty chemicals, has developed a highly effective formula for success: equal parts manufacturing expertise, quality control, and customer-centred service.

While the chemicals produced at the company’s Freetown, Ma.-based facility often comprise a small percentage of the end-use products in which they are used, they nonetheless play vital roles in those products which serve the pharmaceutical, photographic, personal care, agricultural, coatings and polymer industries.

Until recently, though, some of the specialty chemicals produced at the facility were not flowing quite as smoothly as the company’s success. Specifically, a raw material that the company used in the production of an ingredient for a hair spray product was creating some manufacturing challenges.

The company received the material in bulk bags and wanted to load it directly into its process vessel. Unlike a material with high granularity, this fine powder tended to form “rat holes” in the bulk bag in which it was delivered, preventing the material from being fed easily into the process vessel.

And there were other reasons why ISP wanted to re-evaluate the method they were using to charge this raw material, according to Fran Minnock, a 12-year veteran in the company’s process engineering and quality assurance department.

“We needed to control the dust that the material generated into the production atmosphere. We needed to improve efficiency and we needed to accomplish this in an oxygen-free atmosphere,” says Minnock.

Hoping to identify a supplier to meet these multiple challenges, ISP evaluated several solutions such as screw conveyors and other vacuum conveyor technology suppliers, but ultimately turned to PIAB Inc., a supplier of industrial vacuum conveying technology located in Hingham, Mass. The company’s headquarters are based in Taby, Sweden, about 20 km northeast of Stockholm.

PIAB delivered a conveying system consisting of an air-driven vacuum conveyor, pneumatic controller and bulk bag unloader. “PIAB provided us with the two most important elements in our decision-making process, these being a complete solution as well as a cost-effective price,” says Minnock. “The fact that we could remotely mount the Bulk Bag Unloader away from the actual conveyor appealed to us.”

Another benefit was ISP’s ability to test the flow of its product under real-life conditions using both PIAB’s testing facility in Hingham and a unit at the production site. PIAB offers the use of the test facility to all of its potential customers, running a wide variety of materials to assess their conveying characteristics — and identify any possible challenges over distances of varying configuration.

“There’s no doubt that the use of PIAB’s testing facility and the use of the unit at the site was a strong selling point for us,” said Minnock. “It’s not enough for us to see some theoretical equations on a blackboard. We needed to see how our process would work in the plant. PIAB gave us the chance to do that.”

“PIAB’s C-Series 33 Vacuum Conveyor offered us many features to help improve the process,” adds Minnock. The C-Series conveyor’s modular design made it easy for ISP to adapt the conveyor to suit its specific needs. The conveyor’s stainless steel design offers ISP the hygienic (USDA & 3-A accepted) and corrosion-resistant characteristics desired for this application. The conveyor can transport the raw material safely and quietly.

The PIAB vacuum pump is the heart of the vacuum conveying system. The pump is driven by compressed air and is characterized by high flow rates and deep vacuum down to 27 in. Hg. Owing to their unique design, the pumps put the energy in their compressed air supply to maximize use and efficiency, keeping overall energy consumption low. The pump also produces minimal noise in the workplace — only 72-76 dB(A).

Another benefit is that the vacuum conveyors are 100% pneumatically operated, not electrical. Consequently, the need for an explosion-proof electrical rating — a rather expensive proposition — is eliminated. And because the conveyor incorporates few moving parts, routine maintenance and downtime are greatly minimized.

Used in conjunction with the compressed air-driven vacuum conveyors, the PIAB bulk bag unloader is constructed of stainless steel and is a simple, fully contained unit for the unloading of bulk bags. With the bulk bag elevated above the station, the spout of the bag is attached — before it is untied — to an inflatable seal, providing for a totally dust-tight connection. This eliminates the need for gloveboxes, doors or enclosures, and there is no dust connection. The bulk bag unloader is also easily disassembled for periodic cleaning.

If rat holes form in the bulk bag, a cylinder extends, lifting the feed assembly up into the bag, breaking up the bridges in the material and allowing fresh material to flow toward the feed point. The cylinder can be raised and lowered manually, or configured to cycle up and down automatically.

The time savings, as well as the reduction in labour, have been dramatic. In addition, the entire manufacturing process is far more efficient. Previously, it took three people charging 23 bags, moving them manually into a vessel, lifting them up onto a hoist and holding them over a manway. Ultimately, it took these three people a total of 10 hours to prepare the batch for the reactor. With the new PIAB equipment, that process was decreased to four hours.

ISP can now charge bulk bags quickly without oxygen in an inert atmosphere, do it safely, maintain a high level of cleanliness in the plant, and do it despite the fact that the raw-material powder did not have good flow properties.

That’s a formula for success that should keep ISP’s manufacturing process — and profits — flowing freely for a long time to come.

In the manufacturing process that produces the hairspray ingredient, the bulk bag unloader is positioned under the hanging bulk bag, with the spout of the bulk bag attached to the unloader. A pneumatic seal creates a dust-tight connection between the bag and the feed assembly for the vacuum conveying system. The feed assembly features a nitrogen fluidized cone to assist product flow towards the feed point. The nitrogen serves two purposes: it fluidizes the powder and makes the transport piping inert. The entire feed assembly is mounted on a large pneumatic cylinder.

The “PI” in PIAB stands for the symbol *. “AB” is the equivalent of Inc. in English. The Swedish company has Canadian distributors in British Columbia, Alberta, Manitoba, Ontario and Quebec. For more information, visit www.piab.com.