Over the last thirty years it has been proven that the key to optimizing emulsion polymer performance in in‐line polymer systems is the application of ultra‐high mixing energy applied in a way that prevents damage to the polymer’s molecular structure. To accomplish this, the term “infinite shear in zero time” was adopted in the early 1980’s. This term refers to the process of applying ultra‐high mixing energy at the point of polymer / water contact, while the polymer molecule is still coiled up and less susceptible to shear, then avoiding damaging mixing energy after this point. The more efficiently “infinite shear in zero time” is reached, the more effective the activation process will be.
Another fact is that, over the last thirty years, the range of polymers have widened – there are more difficult‐to‐activate polymers in use today, making a polymer system’s performance and versatility more important than ever. Consider that the difference in cost between two polymer systems might be a couple thousand dollars, but the cost implications in excess polymer usage and reduced process performance over the life of a poor performing system could be hundreds of thousands of dollars.
The History of Non‐Mechanical, Hydro‐Dynamic Polymer Blending
In the early 1980’s in‐line polymer blending systems were becoming increasingly more common. The original technologies utilized an impeller driven by a belt and pully with bearings and mechanical seals, which were prone to failure. The neat polymer check valve had very close tolerances, was prone to plugging, and was installed inside the mixing chamber making it very difficult to clean. These systems were inherently unreliable and performed relatively poorly.
In 1986, VeloDyne’s founder and CEO, Paul Plache, began his career in the polymer equipment industry. He joined his family’s business, Fluid Dynamics, where he was involved in the development of a new polymer activation technology – Hydro‐Dynamic, non‐mechanical mixing, trademarked DynaBlendTM*. While this new technology effectively addressed the reliability issues with mechanical blending, it was also proven to be a higher performing polymer activation technology…when sufficient water pressure and flow existed. In side by side trials, this technology consistently met or exceeded the performance of the more complicated and far less reliable mechanical mixers when a minimum of 50 psi differential (psiD) water pressure and ~5 GPM of water flow was present. Pressure and flows below this resulted in reduced performance. In 1990, a new, 75% active content, high molecular weight dispersion polymer was introduced, the Calgon Eclipse. The technology that proved to provide the highest performance at the time was Hydro‐Dynamic mixing, however it was found that 75 psiD was required to optimize the performance of this polymer, thereby setting the new standard for optimum water pressure of Hydro‐ Dynamic mixers to assure all polymers available, today and in the future, could be optimized. Prior to Fluid Dynamics being acquired in 2000, when adequate water pressure wasn’t available, an integral dilution water booster pump was recommended and included to assure adequate mixing energy existing. If, after installation, it was discovered that adequate water pressure wasn’t available, a dilution water booster pump was provided at no cost to the owner.
In 2005, Hydro‐Mechanical blending was introduced to the market. In part, this technology was designed to provide control over the “infinite shear in zero time” process while eliminating the reliance on water pressure and flow for mixing energy. Coincidentally, shortly after Hydro‐Mechanical technology was introduced, the required water pressure of the DynaBlendTM was claimed to be reduced from 50 psiD minimum to 30 psiD. This change in water pressure requirements was made even though there have been no changes to the DynaBlendTM technology in over twenty‐five years, and even though there are more difficult‐to‐activate polymers on the market today than ever before. The only apparent reason for this change was to reduce how often the manufacturer had to bear the cost of a booster pump, even though providing the booster pump could provide greater polymer & process performance for their customers.
When first introduced the DynaBlendTM technology was revolutionary, but like any technology, there was room for improvement. As DynaBlendTM installations grew, a problem in the technology was discovered: because most wastewater treatment plants use non‐potable water for polymer make‐down, the solids in the water were reacting with the polymer solution, over time producing a build‐up of gellike sludge in the four concentric chambers. This had the effect of closing a valve downstream of the mixing chamber, thereby reducing the differential water pressure and diminishing performance of the DynaBlendTM. This problem exists today.
The Development of Hydro‐Mechanical Polymer Activation Started with Advancing the Hydro‐
Dynamic Mixing Process
In 2005, VeloDyne’s founder, Paul Plache, applied for a patent on a new polymer activation technology – the hybrid, Hydro Mechanical VeloBlendTM. As necessity is the mother of invention, the VeloBlendTM was developed to improve the performance of the new, more difficult to activate polymers and address weaknesses in existing technologies.
In mechanical mixing, those weaknesses were: the inability to impart ultra‐high, non‐damaging mixing energy over the full flow range of the system; the common failure of the mechanical seal, and; an inherently unreliable check valve.
In Hydro‐Dynamic blending, those weaknesses were: reliance on water pressure & flow for mixing energy; polymer build‐up and plugging within the mixing chamber, and; an unreliable check valve.
The Process of Invention:
The next generation of advanced polymer activation technologies started with perfecting hydrodynamic, non‐mechanical mixing energy. Born was the VH Series, Non‐Mechanical, Hydro‐Dynamic VeloBlend Technology.
The VH series improved Hydro‐Dynamic mixing in three distinct ways:
Improvement #1 ‐ the polymer injection point was moved closer to the water‐jet producing orifice, thereby more efficiently utilizing non‐mechanical mixing energy (see illustrations below).
The more efficient use of non‐mechanical mixing of the VeloBlend VH series is shown using CFD modeling:
Hydro‐Dynamic blending operating at 10 psi Differential Pressure: Total lack of mixing energy. A booster pump or other means of mixing energy is required to optimize polymer performance. Hydro‐Dynamic blending operating at 30 psi Differential Pressure: Inadequate mixing energy exists at the competitor’s polymer injection point. A booster pump or other means of mixing energy is required to optimize polymer performance.
Hydro‐Dynamic blending operating at 30 psi Differential Pressure: Inadequate mixing energy exists at the competitor’s polymer injection point. A booster pump or other means of mixing energy is required to optimize polymer performance.
Hydro‐Dynamic blending operating at 50 psi Differential Pressure: Adequate mixing energy for some, but not all emulsion polymers. A booster pump or other means of mixing energy is required to optimize polymer performance.
Hydro‐Dynamic blending operating at 75 psi Differential Pressure: Ideal hydro‐dynamic mixing energy. When provided with a pressure regulating valve, control over mixing energy is possible. Typically a booster pump is required to provide this level of differential pressure.
Improvement #2 ‐ A new and improved, plug‐flow, poppet style check valve was introduced.
This new check valve injects polymer directly into the jet of water at a 45 degree angle through an injection quill, further improving the use of non‐mechanical mixing energy, and improving the reliability of the neat polymer check valve.
Improvement #3 ‐ the four concentric chambers were eliminated and a single baffled chamber that produces a high velocity centrifugal force throughout the mixing chamber was introduced. This single chamber design eliminates the buildup of the gel‐like sludge seen in concentric chamber style mixers, and prevents performance degradation over time.
In applications where there is known to be sufficient water pressure, and additional control and versatility is not required, the VeloBlendTM VH series has proven over last twelve years to offer improved performance and reliability over the original Hydro‐Dynamic mixing chamber design.
Considering polymer is typically one of the largest cost in a thickening and dewatering application, second only to sludge disposal in dewatering, polymer performance is paramount. Because of this, the relatively small cost of adding a booster pump to Hydro Dynamic technologies, or employing VeloDyne’s Hydro‐Mechanical polymer activation technology is recommended.
* DynaBlend is a trademark of Fluid Dynamics, Inc.