Monitoramento de estabilidade de águas de sistema de resfriamento – índice de Ryznar e Langelier

Abstract

Water is one of the essential resources for life on Earth, present in various daily activities and indispensable for survival. In the industrial sector, it is used in numerous processes, such as food manufacturing, equipment cleaning, and thermal exchanges in cooling systems. These systems mainly consist of pumps and cooling units, such as cooling towers and chillers. Water plays a central role in these processes and requires constant monitoring, as its conditioning and treatment can lead to corrosion and scaling phenomena in equipment, ultimately affecting process efficiency. To ensure water quality, this study analyzed samples from three cooling towers—Tower S, Tower P, and Tower M—over a five-month period, applying the Langelier Saturation Index (LSI) and the Ryznar Stability Index (RSI), which help identify and quantify corrosive or scaling tendencies of the water. Additionally, physicochemical analyses were conducted, including measurements of temperature, pH, total dissolved solids, calcium hardness, and total alkalinity. Obtaining results from these analyses is crucial for determining the water’s saturation pH and interpreting the Langelier and Ryznar indices. Tower S exhibited high concentrations of the analyzed parameters in four of the five study months, resulting in LSI values of 1.08 and 2.78 in the first and fourth months, indicating a tendency towards scaling. However, it showed -0.64 in the third month, where the water presented a corrosive tendency. For RSI, the sample indicated a balanced tendency (not corrosive or scaling), with values of 6.24 and 6.45 in the second and third months, and 4.09 in the fifth month, indicating a corrosive tendency. Tower P showed low concentrations in some analyses, with LSI values of -0.52 and -1.25 in the first and fourth months, characterizing the water as corrosive. Its RSI values were 9.82 and 9.25 in the fourth and fifth months, indicating a corrosion tendency. Tower M exhibited results of 1.05 and -0.29 according to LSI in the first and third months, indicating a tendency towards scaling and balance. However, during these months, the sample showed RSI values of 6.3 and 8.48, characterizing a balanced and corrosive tendency. In conclusion, Towers S and M showed similar values throughout the study period, indicating a scaling character for LSI and, for RSI, balanced and scaling in most of the analyzed months. Samples from Tower P exhibited a tendency towards corrosion in nearly all study months according to LSI, and in all for RSI.