Air staging application effects on overall steam boiler operation

This paper presents the results of calculation system of main processes in power steam boiler, before and after application of air staging. Modified air injection scheme was implemented during 2015 on the power steam boiler within unit 1 of TPP Kostolac B. Measurements performed on site showed that applied reconstruction led to a permanent loss of the steam boiler power. This study was performed in order to define the cause of such an occurrence and to consider the possibility for regaining the designed steam parameters along with keeping NOx concentration in prescribed limits. This paper discusses the influence of repositioning the air injection location on processes within the furnace. Furthermore, the influence of the redistribution of injected air-flow along the furnace height on important boiler operation parameters has been analyzed. Analysis showed that, with appropriate dosing of air along the height of the existing furnace, it is possible to achieve the optimum of the boiler's operation parameters. Results of research showed that air staging throughout the furnace height in best test case additionally reduces NO concentration (195-225 mg/Nm(3)) and increases the power of x considered boiler (828.8-751.1 MW) with an insignificant decrease of the boiler's efficiency (86.27-86.77%). Furthermore, the designed temperatures of superheated (540-498 degrees C) and reheated (540-518 degrees C) steam have been reached again, whereby the safety of the boiler's operation has been significantly increased. Results of this study improve the present explanation of the processes occurred in the furnace with applied primary measures. They also give directions on defining the most influential parameters on considered processes with the final purpose to increase the efficiency and availability of the entire plant

Air staging application effects on overall steam boiler operation

This paper presents the results of calculation system of main processes in power steam boiler, before and after application of air staging. Modified air injection scheme was implemented during 2015 on the power steam boiler within unit 1 of TPP Kostolac B. Measurements performed on site showed that applied reconstruction led to a permanent loss of the steam boiler power. This study was performed in order to define the cause of such an occurrence and to consider the possibility for regaining the designed steam parameters along with keeping NOx concentration in prescribed limits. This paper discusses the influence of repositioning the air injection location on processes within the furnace. Furthermore, the influence of the redistribution of injected air-flow along the furnace height on important boiler operation parameters has been analyzed. Analysis showed that, with appropriate dosing of air along the height of the existing furnace, it is possible to achieve the optimum of the boiler's operation parameters. Results of research showed that air staging throughout the furnace height in best test case additionally reduces NO concentration (195-225 mg/Nm(3)) and increases the power of x considered boiler (828.8-751.1 MW) with an insignificant decrease of the boiler's efficiency (86.27-86.77%). Furthermore, the designed temperatures of superheated (540-498 degrees C) and reheated (540-518 degrees C) steam have been reached again, whereby the safety of the boiler's operation has been significantly increased. Results of this study improve the present explanation of the processes occurred in the furnace with applied primary measures. They also give directions on defining the most influential parameters on considered processes with the final purpose to increase the efficiency and availability of the entire plant

Mold attack on frescoes and stone walls of Gradac monastery

Microfungi can colonize stone surfaces and form sub-aerial biofilms which can lead to biodeterioration of historic monuments. In this investigation samples for mycological analyses were collected from stone material with visible alteration on stone walls of Gradac monastery exterior. The prevailing fungi found on stone walls were dematiaceous hyphomycetes with melanized hyphae and reproductive structures (Alternaria, Aureobasidium, Cladosporium and Epicoccum species). The frescoes inside the monastery building were also analyzed for the presence of mycobiota. The predominant fungi found on frescoes were osmophilic species from genera Aspergillus and Penicillium. The significant result is identification of human pathogen species Aspergillus fumigatus on frescoes

Comparison of anti-Aspergillus activity of Origanum vulgare L. essential oil and commercial biocide based on silver ions and hydrogen peroxide

The antifungal activities of Origanum vulgare essential oil (EO) and of a biocide based on silver and hydrogen peroxide (Sanosil S003) against seven Aspergillus species isolated from different substrata (stone, brick, silk and paper) of cultural heritage objects in Serbia were evaluated. Microdilution, agar dilution and microatmosphere methods were used to determine minimal fungistatic and minimal fungicidal concentrations (MIC and MFC), and light microscopy to determine structural abnormalities. MIC and MFC values for O. vulgare EO ranged from 0.2 to 5 mg mL−1 and for Sanosil S003 from 5 to 250 mg mL−1. Aspergillus sp. sect. fumigati was the most susceptible isolate, where MIC and MFC values were achieved at 0.5 mg mL−1 for O. vulgare EO, while MIC and MFC values for Sanosil S003 were achieved at 5 and 10 mg mL−1, respectively. Morpho-physiological changes were documented in all isolates, including lack of sporulation, depigmentation of conidiogenous apparatus and conidia, and presence of aberrant fungal structures. O. vulgare EO exhibited stronger anti-Aspergillus activity than Sanosil S003, as demonstrated by the higher MIC and MFC values and fewer morpho-physiological changes observed in the tested Sanosil S003 concentrations. O. vulgare EO could be an excellent alternative to commercial biocides, with high potential in the field of cultural heritage conservation

Simple and Low-cost Fiber-optic Sensors for Detection of UV Radiation

In this paper two simple and low-cost fiberoptic sensors for detection of UV radiation are presented. A U-shaped sensor covered with an UV marker for UV radiation detection and a fiber-optic sensor with one end covered with powder from a mercury lamp are produced and described in details. Both sensors are made of large-core PMMA plastic optical fibers. As UV sources, a solar simulator and four different UV lamps are used. The light spectrum on the fiber output is measured by using an USB spectrometer. Dependence of output light intensity on the distance of end-type sensor with powder from a mercury lamp from UV lamp is investigated as well. On the output of the sensor covered with powder from a mercury lamp are obtained peaks of fluorescent emission at approximately 616 nm and 620 nm wavelengths

Fracture mechanics analysis of damaged turbine rotor discs using finite element method

This paper presents evaluation fracture mechanics parameters in low pressure turbine components. Critical locations such as keyway and dovetail area are experiencing stress concentration leading to crack initiation. Stress intensity factors were evaluated using the J-Integral approach available within ANSYS software code. The finite element method allowed the prediction of the point of crack initiation and the crack propagation using the orientations of the maximum principal stresses. Special attention in this investigation is focused to develop analytic expressions for stress intensity factors at critical location of low pres-sure steam turbine disc. [Projekat Ministarstva nauke Republike Srbije, br. I-174001 i br. TR-35045

Metalloporphyrins on oxygen-passivated iron: Conformation and order beyond the first layer

On-surface metal porphyrins can undergo electronic and conformational changes that play a crucial role in determining the chemical reactivity of the molecular layer. Therefore, accessing those properties is pivotal for their implementation in organic-based devices. Here, by means of photoemission orbital tomography supported by density functional theory calculations, we investigate the electronic and geometrical structure of two metallated tetraphenyl porphyrins (MTPPs), namely ZnTPP and NiTPP, adsorbed on the oxygen-passivated Fe(100)-p(1 × 1)O surface. Both molecules weakly interact with the surface as no charge transfer is observed. In the case of ZnTPP, our data correspond to those of moderately distorted molecules whereas NiTPP exhibits a severe saddle-shape deformation. From additional experiments on NiTPP multilayer films, we conclude that this distortion is a consequence of the interaction with the substrate, as the NiTPP macrocycle of the second layer turns out to be flat. We further find that distortions in the MTPP macrocycle are accompanied by an increasing energy gap between the highest occupied molecular orbitals (HOMO and HOMO-1). Our results demonstrate that photoemission orbital tomography can simultaneously probe the energy level alignment, the azimuthal orientation, and the adsorption geometry of complex aromatic molecules even in the multilayer regime

Inpatient care in Serbia: trends in hospitalization and diagnostics over time

This is the peer-reviewed version of the article: Pejovic Milovancevic, M.; Kesic, A.; Grujicic, R.; Stojkovic, A.; Zivotic, S.; Stupar, D.; Borovnica, V.; Radosavljev-Kircanski, J.; Manojlovic, I.; Stojiljkovic, D. J. Inpatient Care in Serbia: Trends in Hospitalization and Diagnostics over Time. Eur Child Adolesc Psychiatry 2018, 27 (12), 1645–1651. [https://doi.org/10.1007/s00787-018-1191-3

Supplementary data for the article: Ljaljević Grbić, M.; Unković, N.; Dimkić, I.; Janaćković, P.; Gavrilović, M.; Stanojević, O.; Stupar, M.; Vujisić, L.; Jelikić, A.; Stanković, S.; et al. Frankincense and Myrrh Essential Oils and Burn Incense Fume against Micro-Inhabitants of Sacral Ambients. Wisdom of the Ancients? Journal of Ethnopharmacology 2018, 219, 1–14. https://doi.org/10.1016/j.jep.2018.03.003

Supplementary material for: [https://doi.org/10.1016/j.jep.2018.03.003]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2158