Structured catalytic reactor for VOC combustion

VOC emission has recently become a challenge for environmental protection. Catalytic combustion seems a promising method of VOC removal, however, there are still more specific demands concerning the process. The reactor design has to assure enhanced transfer properties accompanied by low flow resistance to reduce the pumping costs. Neither the packed beds nor the classic ceramic monoliths are able to fulfil the requirements. To solve the problem we propose a wire gauze structure composed of several gauze sheets staked. A number of mass transfer and flow resistance experiments were performed for two gauze types and correlations were derived for the Sherwood number and the friction factor. The results were found to be in a reasonable agreement with the literature available. The studied gauze structures were compared with a classic monolith for the assumed case study. The calculated length of the gauze structured reactor was significantly shorter, up to ten times, when compared with a classic ceramic monolith, but the pressure drop was higher

Far field combined AFM and micro-Raman imaging for characterisation of surface of structured catalysts : example of Pd Doped CoOxCoO_x catalysts on precalcined kanthal steel

A coupled AFM-Raman system was used to study the surface heterogeneity of catalytic materials at various stages of their preparation. The catalysts chosen for the analyses were cobalt oxide with and without palladium dopant deposited on surface of pre-calcined steel carriers. Steel carriers are surveyed here in terms of their application as fillers for structured reactors for the catalytic combustion of volatile organic compounds. Upon steel precalcination stage the interfaced AFM-Raman and in situ Raman analyses revealed the evolution of alumina and iron oxide phases on the surface with their final stable forms found as being α-Al_{2}O_{3} and α-Fe_{2}O_{3}. Upon catalyst layering stage AFM-Raman mapping evidenced uniform coverage of precalcined steel carrier with cobalt spinel oxide Co_{3}O_{4}. For the doped catalyst except Co_{3}O_{4} palladium(II) oxide grains were also found on the surface. The differences in the composition of cobalt catalysts were correlated with the differences in their catalytic activity

Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings

This study proposes a method to estimate the lipid content in binding media in paintings that can be used at any laboratory equipped with an infrared spectrometer. The lipid content estimator, termed greasiness index (GI), is defined as a ratio of lipid \nu(C=O) and protein amide I bands at 1743 and 1635 cm−1, respectively. Three Fourier transform infrared (FTIR) sampling techniques were evaluated for GI determination: reflective attenuated total reflection-ATR, specular reflection microscopy-\muSR and photoacoustic-PAS. A set of model painting samples containing three tempera binding media (casein, egg, egg + oil), seven pigments and one varnish type were used in the study. Multivariate analysis was used to evaluate the resulting data. A good reproducibility of GI was obtained by ATR and PAS but not with \mu SR. The discriminative power of the technique is higher for unvarnished samples, but, generally, the GI estimator can be used for the categorisation of binding media in large populations of painting samples analysed with the same FTIR technique (sampling technique, detection, etc.)

Stackelberg Security Games: Models, Applications and Computational Aspects, Journal of Telecommunications and Information Technology, 2016, nr 3

Stackelberg games are non-symmetric games where one player or specified group of players have the privilege position and make decision before the other players. Such games are used in telecommunication and computational systems for supporting administrative decisions. Recently Stackleberg games became useful also in the systems where security issues are the crucial decision criteria. In this paper authors briefly survey the most popular Stackelberg security game models and provide the analysis of the model properties illustrated in the realistic use cases

Diversity and transmission of Aleutian mink disease virus in feral and farmed American mink and native mustelids

Aleutian mink disease virus (AMDV), which causes Aleutian disease, is widely spread both in farmed mink and wild mustelids. However, only limited data are available on the role of wild animals in AMDV transmission and spread. Our aim was to shed light on AMDV transmission among wild mustelids and estimate the effect of intense farming practices on the virus circulation by studying AMDV prevalence and genetic diversity among wild mustelids in Poland. We compared AMDV seroprevalence and proportion of PCR-positive individuals in American mink, polecats, otters, stone martens, and pine martens and used the phylogenetic analysis of the NS1 region to study transmission. In addition, we used a metagenomic approach to sequence complete AMDV genomes from tissue samples. In eastern Poland, AMDV seroprevalence in wild mustelids varied from 22 per cent in otters to 62 per cent and 64 per cent in stone martens and feral mink, respectively. All studied antibody-positive mink were also PCR positive, whereas only 10, 15, and 18 per cent of antibody-positive polecats, pine martens, and stone martens, respectively, were PCR positive, suggesting lower virus persistence among these animal species as compared to feral mink. In phylogenetic analysis, most sequences from feral mink formed region-specific clusters that have most likely emerged through multiple introductions of AMDV to feral mink population over decades. However, virus spread between regions was also observed. Virus sequences derived from farmed and wild animals formed separate subclusters in the phylogenetic tree, and no signs of recent virus transmission between farmed and wild animals were observed despite the frequent inflow of farmed mink escapees to wild populations. These results provide new information about the role of different mustelid species in AMDV transmission and about virus circulation among the wild mustelids. In addition, we pinpoint gaps of knowledge, where more studies are needed to achieve a comprehensive picture of AMDV transmission.Peer reviewe

In search of governing gas flow mechanism through metal solid foams

Solid foams have been intensely studied as promising structured catalytic internals. However, mechanisms governing flow and transport phenomena within the foam structures have not been properly addressed in the literature. The aim of this study was to consider such flow mechanisms based on our experimental results on flow resistance. Two mechanisms were considered: developing laminar flow in a short capillary channel (flow-through model), and flow around an immersed solid body, either a cylinder or sphere (flow-around model). Flow resistance experiments were performed on three aluminum foams of 10, 20, and 40 PPI (pores per inch), using a 57 mm ID test column filled with the foams studied. The foam morphology was examined using microtomography and optical microscopy to derive the geometric parameters applied in the model equations. The flow-through model provided an accuracy of 25% for the experiments. The model channel diameter was the foam cell diameter, and the channel length was the strut thickness. The accuracy of the flow-around model was only slightly worse (35%). It was difficult to establish the geometry of the immersed solid body (sphere or cylinder) because experiment characteristics tended to change from sphere to cylinder with increasing PPI value

Surface Remelting of Mold Inserts Made of NC11 Steel

In the study presented in this paper, the effect of a concentrated heat stream on geometry, microstructure, and hardness of superficial remeltings on NC11 steel is examined. The material is used for disposable mold inserts exposed to intensive abrasive wear in the course of the press-molding of hard aggregate stampings for refractory bricks. As a result of local remelting, the hardness of the steel surface increased and its microstructure was altered. Macro- and microstructure of the remelted areas was examined with the use of optical microscopy and measurements of remelting area geometry were carried out for different parameters of the remelting process. Hardness measurements were taken in the remelting area and in the heat-affected zone. The state of stress in the material before remelting and in the remelted area was also evaluated

Prospective catalytic structured converters for NH3−SCRNH_3-SCR of NOxNO_x from biogas stationary engines : in situ template-free synthesis of ZSM-5 Cu exchanged catalysts on steel carriers

The main objective of this study is to develop highly active catalyst and its preparation method that would meet the requirements of steel carriers for short- channel structured converters for NO x abatement from stationary biogas engines. The in situ synthesis was applied to deposit a series of Cu-exchanged MFI zeolite (ZSM-5) on kanthal sheets. The samples differ in preparation con- ditions: organic template assisted and template-free syn- thesis, Si/Al ratio and catalyst carrier pretreatment (calcined vs. non-calcined). Dip-coating method was used as a reference to compare loading efficiency. In order to evaluate preparation quality and purity of resulting struc- ture the samples were examined by XRD and SEM/EDS at various stages of preparation. For the assessment of mechanical endurance of the deposited catalyst layers the ultrasonication method was used. The results demonstrated high depositing efficiency of the in situ synthesis as well as high activity and selectivity of the Cu-exchanged MFI samples prepared without costly organic template