Korrosionsverhalten ausgewählter Werkstoffe in Lithiumbromid‐Lösung für den Anwendungsfall Absorptionskältemaschinen

Abstract

Korrosionsverhalten ausgewä hlter Werkstoffe in Lithiumbromid-Lö sung fü r den Anwendungsfall Absorptionskä ltemaschinen Corrosion behavior of selected materials in lithium bromide solution for the application absorption chillers B. Brandt * Absorptionskältemaschinen auf der Basis von LithiumbromidWasser stellen eine interessante Möglichkeit zur effizienten und energiesparenden Versorgung mit Kälte dar. Die zum Antrieb erforderliche Wärmeenergie kann idealerweise aus regenerativen Energien, wie z.B. Solarwärme, oder Abwärme aus der Industrie bereitgestellt werden. Um die Energieeffizienz zu steigern, können die Prozesse mehrstufig betrieben werden. Bei den dreistufigen, sogenannten Triple-Effekt-Anlagen, sind im Generator Temperaturen bis zu etwa 200 -220 8C erforderlich. Die Faktoren hohe Temperatur, hohe Halogenidkonzentration (Lithiumbromid) und die Anwesenheit von Wasserdampf führen zu einer besonders starken korrosiven Beanspruchung der Werkstoffe. Aufgabe des vorliegenden Beitrages war deshalb die Betrachtung handelsüblicher Werkstoffe und Inhibitoren auf ihre Eignung für Triple-Effekt-Absorptionskältemaschinen. Die Messungen wurden unter analogen Bedingungen in ruhender Lösung unter nahezu vollständigem Ausschluss von Luft durchgeführt. Die Untersuchungen haben ergeben, dass nichtrostender Stahl hinsichtlich seiner Materialstabilität besonders aussichtsreich ist. Weiterhin hat sich gezeigt, dass die Art des Inhibitors und das Zusammenwirken unterschiedlicher Phasen die Korrosion erheblich beeinflussen können.Absorption chillers on the basis of lithium bromide-water are interesting systems for efficient and energy-saving supply of coldness. The heating energy for the propulsion of the chiller could result ideally from renewable energies, e.g. solar energy, or waste heating energy from industry. The chiller can work as a multiple-stage process for increasing the energy efficiency. For the three-stage-plants, in the generator temperatures of up to 200 -220 8C are necessary. The factors high temperature, high halogenide concentration (lithium bromide) and the presence of water vapour lead to a very high corrosive exposure of the materials.In that reason the task of the present report was the consideration of commercial materials and inhibitors concerning their suitability for the application in triple-effect-chillers. The measurements were carried out under identical conditions, but in unmoved solution and excluding the contact with air.The result of the investigations showed that stainless steel has been identified as a promising material for this application. Furthermore we have found out that the type of the inhibitor and the interaction of different phases have a strong influence on the corrosion processes.

Absorption heat transformer - state-of-the-art of industrial applications

“…In [71] different commercial materials and corrosion inhibitors are analysed regarding their suitability for the application in triple effect absorption chillers. Here, probes of commercial materials in Lithium Bromide solution in combination with corrosion inhibitors were tested in test tubes for one specific working condition (T ≈ 200°C, p ≈ 0.28 MPa).…”

Sustainable Energy Supply by Absorption Chillers and Heat Pumps Using Multifunctional Working Pairs

“…B. Lithiumbromid, nur unzureichend lösbar ist. Zum einen steigt die Korrosivität dieser halogenidhaltigen, binären Lösung durch die stark erhöhte Temperatur massiv an [13] und zum anderen wird mit steigender Temperatur die Hydratgrenze von Lithiumbromid in Wasser bei standardmäßigen Betriebsparametern bereits bei unter 75°C überschritten [45].…”

Sorbent Properties of Halide-Free Ionic Liquids for Water and CO2 Perfusion

“…8−13 Besides the increasing demand for lithium for other purposes (batteries), the corrosivity of the currently employed solutions has technological disadvantages. 14 In the light of these problems, ionic liquids (ILs) have been suggested as alternative sorption media for thermal energy storage and have been explored theoretically and experimentally for closed sorption systems. 15−17 Many ILs, however, involve weakly coordinating counter-anions such as BF 4 − or PF 6 −18,19 which have been shown to undergo hydrolytic cleavage with liberation of HF being unfavorable with respect to corrosion.…”

“…Besides sensible heat storage, phase change materials , and sorption processes are the most prominent storage strategies. , Sorption processes using liquid sorbents are especially attractive and have already been implemented in commercial devices . Most of them rely on concentrated aqueous lithium halide solutions as sorption media which can be regenerated by heat. − Besides the increasing demand for lithium for other purposes (batteries), the corrosivity of the currently employed solutions has technological disadvantages …”