Most US bakeries rely on dilute phase conveying to transfer powders and granular ingredients such as flour, starch, salt and minor ingredients. However, if a snack producer wants to move an ingredient that is friable or requires little or no particle breakage, as is often the case with nuts or whole-kernel corn, a dense-phase system might be preferred, noted Tom Leach, national sales manager, baking and snack industry, Horizon Systems, Lawrence, KS.

Dilute-phase systems generally operate using high air velocity and air volume but lower operating pressure or vacuum, explained Mark Ungashick, executive vice-president, Shick USA, Kansas City, MO. Dense phase is just the opposite, with lower air velocity and air volume and higher operating pressure or vacuum. “A dilute-phase system will usually employ a positive-displacement blower to provide the motive force,” he said. “Sometimes, a fan or regenerative blower can be used in a dilute-phase system. A dense-phase system usually uses a compressor, rotary screw or ring pump to develop the higher range of pressure or vacuum.”

Horizon Systems offers a continuous dense-phase conveying system that substantially reduces product degradation, according to Mr. Leach. Additionally, the company supplies vacuum dense-phase and traditional pressure pot dense-phase conveying, depending on the type of product that needs to be transferred along with the distance and rates required. Not only does the Horizon ConTran continuous dense-phase system require little energy to operate, but it also is designed to reduce segregation of material and product changeover delays, Mr. Leach said.