Engineered Spouting Solution

If you look at the grain handling layout at most large modern elevators today, there’s a certain similarity, especially when it comes to spouting that transfers grain from one leg or conveyor system to another. Grain drops from one place to another via large, square, nearly vertical – a 60-degree slope or steeper.

One engineering firm thinks that in many cases, this is contributing to legs or conveyors functioning at less than 100% of their rated capacity.

“It’s a lot like pouring a carbonated beverage, like beer or soda, into a glass,” says Andrew Knapp, director of operations for the bulk material handling division of Baton Rouge, LA-based APTIM Corp. (832-549-8512). “If you pour the carbonated beverage vertically into the glass, you get a large amount of foam. If you pour the liquid down the side of the glass at an angle, you get much less foam.”

Something similar happens near the outlet of a near-vertical spout. The volume of grain falling through the spout sets up a lot of turbulence in the air, which interferes with the efficiency of the grain flow. This also kicks up a lot of grain dust inside the spout housing, which can become a safety issue.

This wasn’t always the case in the grain industry. In the 1940s through the 1960s, spouting connections were much more customized, often done at much shallower angles. “At a shallower angle coming off, for example, an open belt conveyor, the grain mass retains much more of its shape, so dust isn’t kicked up as much,” says Knapp.

In the 1970s, near-vertical spouting became much more standardized during the rapid increase in grain exports, resulting in a building boom in the industry, and things have been done that way ever since.

Move Into Grain

APTIM has been going back to the older way of designing spouting systems, thus far primarily in the coal and mining industries. In 2017, APTIM began applying this method in the grain industry, starting as part of a major expansion project at an export terminal in the Mississippi Gulf.

Knapp describes the design process as collaborative, involving the engineering firm with equipment suppliers. In this case, APTIM worked closely with suppliers of enclosed belt conveyors, air-supported conveyors, and the shiploading system. The photos on this page show some of the round, noodle-like spouting structures they developed.

According to Knapp, the terminal operator reported a number of important benefits from this new/old approach to design:

• Close to zero dust emissions during shiploading without the addition of dust control equipment, especially critical because of a residential neighborhood nearby.
• Improved electrical energy efficiency both from not having to add dust control and by being able to run equipment at rated capacity.
• Improved grain quality through reduced FM by eliminating free-fall “drops” through the spouts.

Reprinted from Grain Journal July/August 2020 Issue