Glavic Tikeri

Date of Award

December 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemical Engineering

First Advisor

Alshami A. Ali

Abstract

Despite the ongoing research, there remains a significant gap in the understanding of the formation dynamics of mineral scale, particularly calcium carbonate and calcium sulfate. This study primarily aims to elucidate the behaviors of these scales' interactions and deposition. The experimental work was conducted mostly using an in-house-made continuous stirred tank reactor laser setup. By continuously monitoring changes in laser intensity within supersaturated solutions of calcium carbonate and calcium sulfate, their formation kinetics was captured, and variations in induction time under varying physicochemical conditions of temperature and pH was quantified. The laser setup was also used to assess the effectiveness of scale inhibitors in delaying or mitigating scale formation. Key findings reveal that the scaling rate increases, and the induction time decreases as temperatures rise for the co-precipitated scale. At lower temperatures, such as 20 and 30˚C, the formation of the co-precipitate is relatively slow, with an induction time of 11 minutes and 40 seconds at 20℃. A 10℃ increase in temperature reduces the induction time by 45.4% to 6 minutes 22 seconds. It was also noted that while both scale types respond differently to pH changes, the co-precipitates' response was akin to that of calcium carbonate, with the induction time decreasing as pH rises. Moreover, this study provides valuable insights into the formation mechanism through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction analysis (XRD). These techniques reveal calcium carbonate as the dominant scale type in the co-precipitate, exhibiting several polymorphic transformations with changes in temperature and pH. The laser setup was also utilized to evaluate the effectiveness of two commercial inhibitors used at the Grand Forks Water Treatment Plant. This served as a rapid screening method to determine inhibitor efficacy at different concentrations, with optimal inhibition achieved at 30ppm of commercial 2. This research sheds light on the co-precipitation of calcium carbonate and calcium sulfate scale, highlighting how the presence of one scale affects the formation and precipitation of the other. It also underscores the laser setup's potential as a key tool in advanced scale control measures, ultimately facilitating optimized industrial operations and improved resource management.

Download

Share

COinS