Formatted Title
Efficient, Streamlined, and Accurate: An Innovative Inline Reagent Blending System to Avoid the Problems of Batch Mixing
Background/Objectives
Background/Objectives. In the in situ environmental remediation industry, various reagents are employed to address contamination in soil and groundwater. These reagents are commonly mixed with water and injected for distribution into the subsurface. A critical requirement for successful remediation involves the transfer and mixing of specified reagents at requisite mass to mix water ratios.
The most common and simplistic approach to mixing single or multiple reagents with water is batch mixing. Batch mixing involves a labor-intensive process that entails transferring reagent concentrate from containers into a batch tank filled with water. This transfer can be carried out manually or with the assistance of a transfer pump. In each case, adding the ingredients (water and reagents) into a batch tank is typically completed by transferring one reagent at a time, based on mass-to-mix water ratios. Once combined in the batch tank, the fluid is agitated with high-energy vortex mixers, or recirculated until adequately homogenized.
Batch mixing presents several inherent challenges to efficient and accurate mixing and injection; it is labor-intensive and is a redundant, time-consuming, multi-step process. Batching requires a large footprint for mixing tanks with sufficient volume and expensive spill and containment measures must be in place to match. Reagent additions are most often based on volumetric conversions using flowmeters and/or graduated markings on tanks, thereby introducing potential inaccuracies among the mix ratios.
Approach/Activities
Approach/Activities. A unique inline blending injection system was designed and built to increase onsite efficiencies, reduce labor requirements, and improve reagent dose delivery ratios to the remediation sites. The system combines water with up to four liquid reagents, producing a final solution for direct application at its discharge point. The blending system uses positive displacement pumps and mass flow meters in formulated ratios for proper solution ratio control. The reagents are then mechanically blended through a static mixer within a shared pipeline before reaching the discharge point. Each of the pumps connect directly to the bulk reagent concentrate containers and water supply, reducing the overall footprint requirements. Onboard electronic automation controls align the operation in a feedback loop, protecting against out-of-ratio mixing or dry run scenarios, providing highly accurate ratio control of each reagent.
Results/Lessons Learned
Results/Lessons Learned. Field trials have resulted in a significant decrease in labor requirements associated with the inline blending operations, as well as increased production efficiencies through a quicker daily setup and teardown phase. The system’s design and approach eliminates the impact of reagent concentrate variability within the shipping container, improves mixing, and results in a significantly more precise delivery of the reagent dose to the target treatment zone. The use of this innovative system translates to shorter application programs, improved onsite health and safety through reduced manual handling, increased surety of accurate injectant emplacement, and successful contaminant remediation. Details of the system, field trials, and resultant findings will be presented.