Organic Matter Composition More Important than Concentration in Ion Exchange Demineralization of Different Water Qualities for the Production of Steam

Abstract

Fresh water becomes a limited resource in the industry. In order to help chemical industries use other water sources and close their water cycle for the production of steam, a well-founded insight on the challenges and possibilities of switching from one specific water quality to another is needed. A case study for Monsanto Europe N.V. was carried out, but the main findings hold for many more applications, as many industries struggle with water scarcity and feel the need to reuse wastewater. Besides demineralization by ion exchange (IEX), the total organic carbon (TOC) concentration, composition, and the formation of organic acids under boiler conditions were investigated for two different water qualities (Antwerp tap water and wastewater after reverse osmosis (RO) treatment). The comparison included the effect of TOC composition on its removal by IEX and the potential corrosiveness of TOC compounds. Despite tap water showing a more efficient and higher TOC removal compared to RO permeate (93% and 57%, respectively), tap water led to more organic acid formation under boiler conditions. Including the composition of the organic matter in TOC corrosiveness assessment may offer multiple advantages, not in the least economic benefits, when less treatment is required in order to meet the TOC limit value.

Organic Matter and Microbial Cell Density Behavior during Ion Exchange Demineralization of Surface Water for Boiler Feedwater

“…Dimensioning of the lab-scale setup was based on a full-scale IEX installation at BASF Antwerp N.V., treating the same surface water, and calculations can be found in Table S2 together with the regeneration parameters. More practical information about the operation and regeneration procedure is described in previous research …”

“…The most important parameters for the evaluation of efficiency of the demineralization process such as the total TOC load, the relative adsorption, and regeneration efficiency were calculated. More information about these definitions and their respective equations can be found in previous research …”

“…The investigation of the thermal stability, or in other words the susceptibility to thermolysis, of the different water streams was performed using a mini-boiler. The configuration and the operational procedure of the lab-scale mini-boiler setup are described in previous research . The current experiments were conducted at a temperature of 500 °C, a back-pressure of 120 bar, and a residence time of 1.24 s to mimic superheater conditions.…”

“…In addition to the general TOC analyses, liquid chromatography in combination with organic carbon detection (LC-OCD) characterization was performed to provide insight into the TOC components retained in each column. Boiler experiments with the demineralized water from each water source were conducted to detect differences in the formation of corrosive components (organic acids) during hydrothermolysis, and the results were compared with previous research on formation of organic acids during boiler conditions of demineralized tap water …”

Effect of Film-Forming Amines on the Acidic Stress-Corrosion Cracking Resistance of Steam Turbine Steel

“…Especially the increasing amount of organic acids in the first condensate of low-pressure steam turbine sections can cause serious corrosion damage, such as SCC [26][27][28][29][30][31][32][33][34][35]. These organic acids originate from the breakdown of organic impurities by hydrothermolysis in boilers and superheaters [19,[36][37][38][39][40][41]. Film-forming amines, added during operation, might also tackle the issues resulting from impurities in the water.…”