A new CSTR method for scale inhibitor evaluation

Abstract

In various industries, the mineral scale control is critical to ensure productivity, facility integrity, and health and safety. Among different scaling control methods, the scale inhibitor is one of the most commonly used and economic methods. To optimize scale inhibitor applications, it is required to accurately and efficiently evaluate scale inhibitor performances, and determine the required minimum inhibitor concentration (MIC). However, the traditional NACE static bottle tests, dynamic scale loop (DSL) tests, and the batch laser test are limited by their testing conditions, consumable costs, or testing efficiency, especially when minimal inhibitor information is available. This study developed a new brine chemistry inhibitor (BCIn) CSTR (continuous stirring tank reactor) evaluation method to overcome these limitations. In the BCIn CSTR testing, the supersaturated solution with the same SI is pumped into the reactor without the continuous supply of scale inhibitors. As a result, the scale inhibitor concentration is diluted exponentially, which significantly accelerates the crystallization process and generates much sharper and more reproducible end point. More importantly, this study also developed a mechanistic model that correlates the crystallization processes of the BCIn CSTR and batch laser testing. This correlation model makes the BCIn CSTR method and the batch laser testing method equivalent in terms of scale inhibitor performance evaluation. Using this method, the inhibitor performance screening can usually be finished within 20 min with better accuracy and reproducibility (less than6.6% error). Furthermore, the MIC can be accurately determined by as few as one BCIn CSTR test using the correlation model, instead of via multiple lengthy batch laser tests. We believe this BCIn CSTR method can significantly improve the evaluation of scale inhibitor performance and MIC determination.