Pneumatic conveying is one of the most efficient methods of transporting products or materials from Point A to Point B. All it takes is a sealed tube or a series of sealed tubes and either compressed air or a vacuum inducer to create air flow from one end to the other. Then, just introduce the…whatever you’re moving and WHOOSH! Off it goes. (If you’re having trouble visualizing a pneumatic conveyor system, just think of the tubes that bring the canisters back and forth between customers and tellers in the drive-through lanes at your bank.)
Pneumatic technology in general has been around for quite some time. But just when, exactly, was it first put to use as a material conveyor? And from whence did this idea originate?
Blowin’ In the Wind
The true origin of pneumatic conveying is hard to pin down. The first recorded use of pneumatics for material conveying purposes comes, perhaps unsurprisingly, from Germany, circa 1950. A crafty German by the name of Gasterstadt made the first forays into pneumatic conveying, developing the first pressure drop flow meter and experimenting with 100 meter-long horizontal pipes. Professors Rumpf and Barth of Karlsruhe University (now the Karlsruhe Institute of Technology) carried Gasterstadt’s torch onward into the 1960s.
Further advances were made in 1960s-era Japan, when a professor at Nagoya University tasked a team of students with finding a solution for solid material conveying that would work throughout a multi-level facility. Several of the students involved went on to make significant advances in the science of pneumatic conveying; one even became a professor in the subject at Osaka University and, later, a technical advisor for the Hosokawa Research Foundation.
In the United States, major companies in the energy generation industry and adjacent industries put a good deal of time and money into advancing pneumatic conveyor technology. R&D teams from Exxon, Union Carbide, and especially Dow Chemical developed innovative ideas that would make pneumatic conveying more efficient and more effective. Soon, two different schools of emerged that ultimately led to the two different types of pneumatic conveying used today.
Dilute Phase vs. Dense Phase Conveying
Dilute phase pneumatic conveying technology is based on Gasterstadt’s original designs. This method uses low pressure moving air (or another gas) at high velocity to carry products or materials throughout the system. Although faster and effective for a wider range of materials, dilute phase conveying is also less energy efficient and can cause more damage to the conveyed product.
Dense phase conveying was developed by researchers at Cambridge University in Great Britain. This method is more or less the opposite of dilute phase conveying, as it uses high pressure gas to move materials at low velocity. It is a more energy efficient process, but is applicable to a far smaller range of materials.