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Membrany dla nowoczesnych elektrowni węglowych wytwarzających czystą energię


  artykule opisano rozwój innowacyjnych materiałów ceramicznych stosowanych jako membrany do separacji tlenu z powietrza, wspiera- jących procesy separacji CO2 w "czystych" elektrowniach węglowych, pracujących w technologii oksyspalania. Przedstawiono główne kon- cepcje wychwytu CO2 ze spalin (CCS, ang.: Carbon Capture and Storage), ze szczególnym uwzględnieniem procesu oxyspalania. Przybli- żono zasadę działania oraz rolę membran separujących tlen w procesach CCS. Szczegółowo opisano perowskit Ba0,5Sr0,5Co0,8Fe0,2O3-δ (BSCF 5582), posiadający jeden z najwyższych współczynników przenikalności tlenu i przedstawiono badania mikrostruktury tego materiału. This article describes development of innovative ceramic materials to be applied as oxygen separating membranes in “zero-emission" fossil- fuel power plants, operating in the oxyfuel technology. Main concepts of CO2 capture and storage (CCS) are presented. The principle of operation and the role of oxygen transport membranes (OTM) in the CCS processes are described. The perovskite-structured Ba0,5Sr0,5Co0,8Fe0,2O3-δ (BSCF 5582) is the most promising candidate for OTM material featuring one of the highest oxygen permeation rates. The degradation of permeation processes in BSCF 5582 and an example of unstable material microstructure is presented. Słowa kluczowe: BSCF, membrany do separacji tlenu, perowskit, elektrownia węglowa, mieszane przewodniki jonowo-elektronowe Key words: BSCF, oxygen transporting membranes, perovskite, fossil-fuel power plant, mixed ionic-electronic conductors MIEC.Wstęp. Współczesny rozwój cywilizacyjny jest nieodzownie związany z nieustannym wzrostem za- potrzebowania na energię elektryczną we wszystkich sektorach gospodarki. Zgodnie z danymi raportu Agen- cji Rynku Energii S.A. [1], do roku 2030 największy wzrost zapotrzebowania na energię elektryczną w Pol- sce nastąpi w sektorze usług (o 60%), gospodarstwach domowych (o 50 %) i w przemyśle (ok. 22 %)[...]

Microstructure and properties of the protective Ti-Al-Si-Ag coating on Timetal 834

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One of the major limitations of Timetal 834, the near-A titanium alloy, that is currently restricting its use at high temperatures is its poor oxidation resistance. In order to improve oxidation resistance of Timetal 834, protective coating based on V-TiAl intermetallic alloy with Si and Ag admixtures was produced by magnetron sputtering. Analytical scanning and transmission ele[...]

Microstructural evolution of HR6W alloy during ageing at high temperature DOI:10.15199/28.2016.5.1


  The HR6W alloy (23Cr40Ni30Fe7WTiNb) is a candidate for boiler components of advanced ultra-supercricical (A-USC) conventional power plants. The influence of isothermal ageing at 700°C and 900°C for up to 110 hours on the microstructure of HR6W alloy was investigated in detail by advanced scanning and transmission electron microscopy methods. The results show that, beside primary MX carbonitrides, the M23C6 and Laves phase, Fe2W, were precipitated in the austenitic matrix. Their size and spatial distribution depend on ageing conditions. Microstructure changes influenced the hardness of the investigated alloy. Key words: HR6W, microstructure, scanning electron microscopy (SEM), transmission electron microscopy (TEM), steam power plant (SPP).1. INTRODUCTION The HR6W is Ni-Fe based alloy produced by Nippon Steel & Sumitomo Metal Corporation with a nominal composition of 23Cr40Ni30Fe7WTiNb designed for tubing, especially for superheaters and reheaters coils and for thick-walled elements of boilers. The HR6W alloy is the candidate for advanced ultra-supercritical (A-USC) boiler pressure elements owing to its superior creep and oxidation resistance at high temperature [1÷4]. The aim of the study was to examine a stability of the HR6W alloy microstructure during ageing at 700°C and 900°C affecting its mechanical properties during service in the power plant. The highest ageing temperature was chosen based on phase equilibrium diagrams and corresponds to operating temperature of 670°C for up to 200 000 hours service for HR6W alloy [5]. 2. MATERIAL AND EXPERIMENTAL DETAILS The chemical composition of the investigated HR6W alloy and standard requirements for HR6W alloy are presented in the Table 1. The alloy was delivered as the tube with outside diameter of 38 mm and wall thickness of 8.8 mm. The as-received alloy was solution treated at temperature range of 1190÷1250°C followed by fast cooling [6]; the exact parameters of heat treatment were[...]

The microstructure of the Sanicro 25 steel after steam oxidation studied by advanced electron microscopy and spectroscopy methods DOI:10.15199/28.2016.5.3


  Increase of the coal fired power plants efficiency is inseparable with an increase of the steam conditions. Currently used 9÷12% Cr steels are not able to withstand pressure of 30 MPa at 700°C for a long time due to their microstructure instability leading to fast damage. Development of new Fe-based materials able to work under advanced ultra-supercritical (A-USC) conditions for a long time is the key of importance. Present paper deals with a microstructure of the prospective, 22% Cr austenitic steel, Sanicro 25, heat treated or oxidized in water vapour at 700°C. Detailed characterization of the steel was performed using X-ray diffractometry as well as scanning and transmission electron microscopy techniques. Investigation led to establish the effect of temperature and water vapour environment on the microstructure stability of this modern austenitic steel. The results showed that the microstructure of the aged steel consists of M23C6 and Laves phase precipitated on the grain boundaries as well as ε-Cu, NbN, M23C6 and Z-phase precipitated within the grains. After oxidation at 700°C up to 5000 h in water vapour, Sanicro 25 developed a thin protective oxide scale at the surface, consisting mainly of Cr2O3 plates, characteristic for steels oxidation in vapour. Key words: Sanicro 25, TEM, oxidation, water vapour, A-USC.1. INTRODUCTION Nowadays, environmental protection takes a particular significance due to high emission of CO2, which is one of the major greenhouse gases causing global warming. Major CO2 sources are coal-fired power plants, therefore particular efforts are made in order to decrease the CO2 emission by increasing the thermal efficiency of the power plants due to enhancing temperature and pressure of the steam to 700°C and 30 MPa, respectively. Such change, however, has strong impact on the microstructure stability and lifetime of the currently used materials. Commonly used 9÷12% Cr steels are not suitable to operate at t[...]

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