Impact of the oxy-fuel combustion on the corrosion behavior of advanced austenitic superheater materials

AbstractAlthough the road-map of the oxy-fuel process seems to be very advanced, there are still plenty of open questions. One of the significant ones is the corrosive behaviour of the heat exchanger surfaces. The Institute of Combustion and Power Plant Technology, University of Stuttgart, performs research on the fireside corrosion under oxy-fuel and conventional combustion conditions for the current and supercritical power plants considering the influence of combustion modus, gas atmosphere and fly ash deposits on the waterwall and superheater surfaces. Since the oxy-fuel-combustion atmosphere is composed of recirculated flue gases and pure oxygen, significantly higher concentrations of CO2, SO2 and H2O are present compared to the conventional combustion of coal with air as an oxidizer. In the here presented study the influence of an oxy-fuel combustion of a hard-coal on the surface of selected superheater materials is discussed and compared to the results obtained for lignite. Especially the interactions between the flue gas atmosphere, ash deposits and heat exchanger materials are studied in detail. The investigation encompassed in this paper has been focused on impacts of oxide-scale growth, carbon enrichment of the materials and sulphur-induced corrosion.Increased sulphur-induced corrosion has been observed in samples exposed to the oxy-combustion atmosphere. The noticed higher depth of corrosive attack of the oxy-fuel samples might be explained by a higher partial pressure of SO2 which is characteristic for oxy-fuel process. Moreover in certain cases the sulphur might be released by the deposits. Beside that, the oxy-fuel samples were exposed to much higher partial pressures of carbon dioxide comparing to the air-case leading apparently to rapid and massive internal carbon enrichment in the oxide scale. Moreover dependence between the chromium content and oxidation ability of the austenitic materials surfaces was noticed under oxy-fuel conditions

Stellar turbulence and mode physics

An overview of selected topical problems on modelling oscillation properties in solar-like stars is presented. High-quality oscillation data from both space-borne intensity observations and ground-based spectroscopic measurements provide first tests of the still-ill-understood, superficial layers in distant stars. Emphasis will be given to modelling the pulsation dynamics of the stellar surface layers, the stochastic excitation processes and the associated dynamics of the turbulent fluxes of heat and momentum.Comment: Proc. HELAS Workshop on 'Synergies between solar and stellar modelling', eds M. Marconi, D. Cardini, M. P. Di Mauro, Astrophys. Space Sci., in the pres

Treatment Wetlands

Overview of Treatment Wetlands; Fundamentals of Treatment Wetlands; Horizontal Flow Wetlands; Vertical Flow Wetlands; French Vertical Flow Wetlands; Intensified and Modified Wetlands; Free Water Surface Wetlands; Other Applications; Additional Aspects

Fireside Corrosion of Applied and Modern Superheater-alloys Under Oxy-fuel Conditions

Abstract Operation of oxy-fuel power plants under ultra-supercritical parameters would help to overcome, to a certain extent, efficiency penalties from air separation and CO 2 -compression units. To improve the knowledge on material behavior under oxy-fuel combustion six candidate superheater alloys, varying from martensitic via iron-base austenitic to nickel-base were chosen and exposed at metal temperature of 580 °C and 650 °C to real oxy-fuel combustion conditions in 3MW combustion test rig of Enel and subsequently moved for further tests to laboratory corrosion test set-up at IFK. Exact definition of combustion conditions was based on measurements performed by IFRF

Математическое моделирование возникновения и распространения лесных пожаров с учетом противопожарных барьеров

С помощью метода математического моделирования изучается процесс распространения верховых лесных пожаров при наличии противопожарных разрывов и заслонов. Математически данная задача сводится к решению уравнений Рейнольдса для турбулентного течения с учетом химических реакций. Для получения дискретного аналога использован метод контрольного объема. С помощью численных расчетов получены распределения полей скорости, температуры, концентраций кислорода, летучих продуктов пиролиза, горения и объемных долей конденсированной фазы, получены контуры распространения верховых лесных пожаров, определена зависимость размеров противопожарных разрывов и заслонов при которых верховой пожар прекращает распространение.Using the method of mathematical modeling, the propagation of high forest fires in the presence of fire breaks and barriers is studied. Mathematically, this problem reduces to solving the Reynolds equations for a turbulent flow, taking into account chemical reactions. To obtain a discrete analog, the control volume method was used. Using numerical calculations, the distributions of the fields of velocity, temperature, oxygen concentrations, volatile pyrolysis products, combustion, and volume fractions of the condensed phase, the propagation contours of upland forest fires were obtained, the dependence of the size of fire breaks and barriers at which the top fire stops propagation was determined

Deciphering the Role of Humoral and Cellular Immune Responses in Different COVID-19 Vaccines - A Comparison of Vaccine Candidate Genes in Roborovski Dwarf Hamsters

With the exception of inactivated vaccines, all SARS-CoV-2 vaccines currently used for clinical application focus on the spike envelope glycoprotein as a virus-specific antigen. Compared to other SARS-CoV-2 genes, mutations in the spike protein gene are more rapidly selected and spread within the population, which carries the risk of impairing the efficacy of spike-based vaccines. It is unclear to what extent the loss of neutralizing antibody epitopes can be compensated by cellular immune responses, and whether the use of other SARS-CoV-2 antigens might cause a more diverse immune response and better long-term protection, particularly in light of the continued evolution towards new SARS-CoV-2 variants. To address this question, we explored immunogenicity and protective effects of adenoviral vectors encoding either the full-length spike protein (S), the nucleocapsid protein (N), the receptor binding domain (RBD) or a hybrid construct of RBD and the membrane protein (M) in a highly susceptible COVID-19 hamster model. All adenoviral vaccines provided life-saving protection against SARS-CoV-2-infection. The most efficient protection was achieved after exposure to full-length spike. However, the nucleocapsid protein, which triggered a robust T-cell response but did not facilitate the formation of neutralizing antibodies, controlled early virus replication efficiently and prevented severe pneumonia. Although the full-length spike protein is an excellent target for vaccines, it does not appear to be the only option for future vaccine design

Current and Future Issues in BPM Research: A European Perspective from the ERCIS Meeting 2010

Business process management (BPM) is a still-emerging field in the academic discipline of Information Systems (IS). This article reflects on a workshop on current and future issues in BPM research that was conducted by seventeen IS researchers from eight European countries as part of the 2010 annual meeting of the European Research Center for Information Systems (ERCIS). The results of this workshop suggest that BPM research can meaningfully contribute to investigating a broad variety of phenomena that are of interest to IS scholars, ranging from rather technical (e.g., the implementation of software architectures) to managerial (e.g., the impact of organizational culture on process performance). It further becomes noticeable that BPM researchers can make use of several research strategies, including qualitative, quantitative, and design-oriented approaches. The article offers the participants’ outlook on the future of BPM research and combines their opinions with research results from the academic literature on BPM, with the goal of contributing to establishing BPM as a distinct field of research in the IS discipline

Scenario Analyses Concerning Energy Efficiency and Climate Protection in Regional and National Residential Building Stocks. Examples from Nine European Countries. - EPISCOPE Synthesis Report No. 3

This report documents methodological aspects and selected results of the scenario analyses to assess refurbishment as well as energy saving processes and project future energy consumption.. It covers scenario calculations conducted for regional residential building stocks in Salzburg/Austria, the Comunidat Valenciana/Spain, the Piedmont Region/Italy, the national non-profit housing stock in the Netherlands as well as the national residential building stocks in Germany, England, Greece, Norway, and Slovenia. Thereby, the objective of the scenario analysis is not a prediction of future energy demand in the respective building stock. Rather, the objective is to show the potential future impact of predefined assumptions. This may help respective key actors and policy makers to decide on strategies and policies for transforming building stocks towards carbon dioxide neutrality