By Dan Haugh

A modular, mobile production system allows chemicals to be transported in their dry, stable state and mixed on-site as needed.

Over the last decade, the economics of complex manufacturing have expanded to take into account truly global markets and swift-changing demand. Production facilities that were once expansive and centralized have been reorganized into networks of smaller-volume, regional production sites.

In addition, cost-reduction and environmental-stewardship initiatives are crossing paths, as production reclaims the revenue sources that can be found in hitherto-forgotten waste streams. For these reasons, mobile production, or modular pre-processing, is increasingly vital to the process industries, including in oil & gas, chemical, energy, food & beverage, pharmaceutical and others.

In other words, one way to overcome challenges in processing raw materials in uncertain operating environments is to mix or pre-process at the point-of-use rather than trucking feedstock directly from the sourced location. Mixing material at point-of-use reduces transportation and processing costs and improves chemical volume and quality.
Extraction challenges, production boundaries

Even in a controlled plant environment, homogenous blending of dry and wet ingredients to specific ratios is a challenge. Doing the same in the field requires a different, unconventional approach. One example can be taken from the world of minerals and mining.

As is well known, natural-resource mining is more often than not conducted in remote areas. Given a lack of infrastructure and utilities, the transportation and storage of chemicals used in mineral extraction is a significant cost and drain on profits. Moreover, even in ideal conditions, transporting sensitive chemicals in their fluid state isn’t a good idea. 

When a natural-resources customer had this problem, Hapman engineers developed an innovative solution that allowed the customer to boost operating efficiency and decrease costs, using a modular, mobile production system.

Process chemicals had been trucked to the remote work site as a premixed liquid contained in large plastic totes. This was problematic for several reasons. Storing and transporting chemicals in totes makes them susceptible to viscosity degradation, which can negatively impact process efficiency.

In addition, these polymeric compounds could react adversely in the presence of UV light, oxidation, temperature fluctuations and contamination from bacteria or other compounds. Stabilizers can be added to slow polymer chemical bonds breakdown, but this adds costs and raises further contamination possibilities.

Another drawback was that to maintain uninterrupted operation, the totes had to be hauled by flatbed trucks in large numbers. The chemical’s fluid weight increased both transportation and labor costs.

Prototype to best practices

The solution was to instead transport the chemicals in their stable dry state and mix them on-site as needed, with available water. Hapman rigged a 40-foot flatbed trailer with a fully functional, customized mobile-mixing delivery system, ready to go wherever it was needed.

The unit reduced the amount of chemicals needed, decreased transportation and labor costs, maintained needed chemicals viscosity and made overall operations more efficient. Controlling the dry material-to-water ratio allowed tailoring the solution to the process as field conditions changed. The mobile approach allowed for a wide range of different concentrations. In either continuous- or batch-control, operators can select concentrations and quickly respond to changing work site requirements.

This mobile unit meets local and federal transportation requirements, and its maximum height won’t exceed the lowest major highway overpasses. The system withstands all weather conditions, as well as the wear and tear of highway speeds and rough off-road environments. 

Mobile-mixing cornerstone capabilities are delivered by Hapman’s Solidquid eductor technology, which measures and adds dry chemicals to an accuracy of 0.5%, while recording the results. In some cases, where several materials are required, the system weighs multiple components — either in batch- or continuous-mode — and mixes them together through a common eductor. Solidquid’s vortex action effectively achieves a thorough blending of fluids and powders.

The user’s control scheme required a unique loss-and-weight algorithm, developed by Hapman engineers. The loss-and-weight feeding system achieved the tight mixing tolerances the application required.

Starts with eductor

At the system’s heart is an eductor that, along with a unique wetting cone, pre-wets the material. As the eductor draws in the pre-wetted material via a vacuum created by Venturi effect, it further blends the slurry with the motive liquid, generating a turbulent mixing action. The Hapman system controls flow to the eductor and wetting cone to precisely the desired ratio of powders to liquid.

The Helix flexible screw conveyor moves chemical powder from bulk bag unloader into the mixing process. Mixing system moving parts are hydraulically driven, though standard electric motors could as easily be used. Bag house and storage bin accommodate both bulk bags and dry powder vacuum-transferred from another bulk-handling truck. A collection system prevents dust from leaving the system. Finally, the hopper, set beneath the dust collector, has a Plexiglas window, allowing operators to monitor material in the on-board storage hopper.

On-board pumps deliver sufficient flow and pressure to the eductor, fed by a PosiPortion feeder. Software-controlled process automation precisely measures chemical solution delivery. The scale system, unique in design, isolates its load cells in transport mode. Auto-calibration allows users to validate load cells before each operation. A single operator runs the entire system, and all controls on-board are easily accessible.

Innovating on the edge

Hapman’s mobile mixing system provided the ability to mix dry chemicals at the job site as needed. It also:

• Reduced transportation and labor costs

• Increased the quality/viscosity of the chemicals

• Decreased the amount of chemicals required to do the job

• Improved the process by eliminating chemical quality variability

The mobile mixing system allows weighing of the dry chemical material and measuring an accurate amount of powder, then providing valuable usage reports. Chemical mixture delivery is more concentrated compared to the previous system. The solution proves efficient and cost-effective. Other industries mixing dry material outside of a traditional plant environment could benefit from this technology.

Dan Haugh is a product manager with Kalamazoo, Mich.-based Hapman. Haugh earned his Bachelor of Chemical Engineering degree from Georgia Institute of Technology, with a concentration in polymer science, and graduate work in biochemical engineering. He also studied electrical engineering at the University of Houston and has worked in the pharmaceutical, chemical, food, packaging, energy and manufacturing industries.