Repco Food Premix Dense Phase Conveying Case Study

The old transfer created housekeeping, segregation and cleanout loss

Repco’s vitamin and mineral premix operation used a bucket elevator to move finished blends from the mixer to packaging.

Coperion’s project account says the decade-old system produced housekeeping problems, product segregation and significant cleanout loss.

Those three symptoms point to different mechanisms: open transfer and leakage affect housekeeping, repeated free fall can promote segregation, and inaccessible retention zones increase product loss.

Representative full-scale testing drove the selection

Repco and Coperion tested several blended premixes at the Bulk Solids Innovation Center, operated with Kansas State University.

The trials were used to determine whether dense-phase pressure conveying could move the blends consistently without unacceptable segregation.

Transferable lesson: The evidence came from the real material at system scale, not from the label “dense phase” or a generic low-velocity claim.

The installed system included the complete receiving boundary

The published arrangement comprised an Omniveyor pressure vessel, PLC, conveying pipework, a diverter valve, specially designed hopper lids and modular cartridge bin vents.

The pressure vessel received material from the mixer. The line then delivered it to packaging destinations through controlled routing.

Receiver venting matters because conveying gas has to leave without carrying excessive product into the room or creating backpressure that shifts the operating point.

Dense-phase performance is material and route specific

Pressure-vessel conveying works as a batch sequence: fill the sender, close the boundary, pressurise, convey, depressurise and prepare for the next transfer.

The useful operating window balances solids loading, gas velocity, pressure demand and transfer time.

Premixes can contain particles with very different sizes and densities. Too much velocity or repeated acceleration can increase attrition and segregation, while an unstable low-velocity condition can leave material in the line.

The full-scale trials were therefore important for more than nominal capacity. They provided a way to observe whether the representative blends moved through the proposed architecture without the quality problem that triggered the project.

Routing creates distinct acceptance cases

A diverter and several packaging destinations do not necessarily present the same resistance or cleanout behaviour.

Each route should be tested for transfer completeness, vent performance and residual material.

The PLC recipe should bind the selected destination to the correct valve position and prevent a batch from starting when the receiving hopper or bin vent is unavailable.

Blend protection needs its own acceptance method

A conveying trial should compare the blend before and after transfer using a sampling plan that can detect segregation at the scale relevant to the package.

One convenient grab sample is weak evidence. Samples should cover the transfer sequence and credible differences between early, middle and late discharge.

The acceptance record should include material condition, batch size, pipe route, gas flow, pressure, transfer time, residue and the analytical variability before and after conveying.

The results are attributed to Repco and Coperion

Coperion states that the system improved plant cleanliness, product quality and reliability while providing full process automation.

The source does not publish numerical values for dust reduction, segregation, yield recovery, availability or energy use.

Those improvements can be reported as project-party observations, but they should not be converted into independent percentages.

Hygienic design continues beyond the conveying pipe

Food-premix service needs controlled access to the sender, diverter, hopper lids and filter elements.

Dead zones can retain a concentrated minor ingredient that later enters another formulation.

A cleaning study should recover and quantify residue from the hardest locations, then connect the result to allergen, nutritional and formulation risks.

The published account supports the equipment scope and qualitative outcome. It does not state a validated cleaning limit or changeover time.

Dust safety and product quality share interfaces

Bin vents and filters keep conveying gas and powder separated, but collected fine material can also form a combustible dust inventory.

Protection, grounding, isolation and safe filter maintenance should be assessed without compromising hygienic access.

The useful design is the one that engineers can inspect and operators can clean while the safety functions remain intact.

Review points for a similar food-premix project

• Test the worst credible blend, including fine and low-dose ingredients.
• Define a statistically useful segregation and uniformity acceptance plan.
• Include mixer discharge, sender filling, route switching, receiver venting and package feed in the boundary.
• Measure retained product and cleaning time at every product-contact zone.
• Challenge a dirty filter, interrupted batch and restart with material in the line.
• Complete food-hygiene and combustible-dust reviews for the installed arrangement.

Use the dense-phase selection and design guide to develop the test matrix.