Circular economy for evaluating technologies to eliminate colloidal silica from boiler feedwater in thermoelectric plants

Abstract

In Cuba, it is essential to develop a strategy that leads to a circular economy production model in sectors of the chemical industry, and especially in thermoelectric power plants, where the high consumption of technical water for boiler feedwater impacts production costs without the possibility of reusing this water. The presence of colloidal silica in freshwater represents one of the most critical challenges in steam-cycle thermoelectric plants, due to its capacity to generate scale in boilers and deposits in turbines. The objective of this study is to evaluate, from a circular economy perspective, possible technological alternatives to eliminate colloidal silica from boiler feedwater at the Cienfuegos Thermoelectric Power Plant. This study integrates a circular economy approach to water with a multi-criteria comparative analysis of treatment technologies, demonstrating that ultrafiltration (UF) is the optimal alternative for the removal of colloidal silica prior to demineralization systems. Applying the Analytic Hierarchy Process (AHP) method, technical, economic, and environmental criteria are evaluated to support the final selection. The proposed solution offers high efficiency, reduced purging, a smaller environmental footprint, and operational stability, aligning with the circularity of water resources and validating the second and third principles of the circular economy, as demonstrated by the Inédit circularity index and Circular Trans indicators. A feasibility study for technology transfer was subsequently conducted.