AP08_4.vp 1 Introduction In all areas of particulate technology where solid particles are handled, structures coming into contact with particles ex- hibit wear. A major constraint of high intensity agitation is the possibility of developing erosion wear of the impeller blades due to the presence of solid particles in the liquid. [5, 6] In some applications, this wear can be so severe as to limit the life of a component, while in others it may be negligible [2]. All particles cause some wear, but in general the harder they are, the more severe the wear will be [3]. The materials used in plants differ in their susceptibility to erosive wear in the mech- anism by which such wear occurs. The erosion of a pitched blade impeller caused by par- ticles of higher hardness (e.g. corundum or sand) can be described by an analytical approximation in exponential form of the profile of the leading edge of the worn blade (Fig. 1) � �H R C k R( ) exp ( )� � �1 1 , (1) where the dimensionless transversal coordinate along the width of the blade is H y r h � ( ) (2) and the dimensionless longitudinal (radial) coordinate along the radius of the blade r is R r D � 2 . (3) Parameters h and D characterize the blade width and the diameter of the impeller, respectively. The values of the parameters of Eq. (1) – the wear rate constant k and the geometric parameter of the worn blade C – were calculated by the least squares method from the experi- mentally formed profile of the worn blade. While the wear rate constant exhibits a monotonous dependence both on the hardness of the solid particles and on the pitch angle �, [1, 2] the geometric parameter of the worn blade is dependent on the pitch angle and, in linear form, on time. A recent investigation [2] shows that the latter parameter decreases hyperbolically with increasing blade hardness. All men- tioned investigations were carried out in the same scale of the pilot plant mixing equipment (diameter of the vessel D � 300 mm). This study attempts to extend our knowledge about the influence of the parameters of the mixing process, and also the influence of the characteristics of the solid-liquid sus- pension on the erosion wear of the blade of pitched blade impellers, i.e. to determine the effect of the concentration and size of the solid particles on both parameters of Eq. (1), and finally to observe the effect of impeller speed n. 2 Experimental Setup A pilot plant mixing vessel made from stainless steel was used (Fig. 2), with water as a working liquid (density �l � 1000 kg/m 3, dynamic viscosity � � 1 mPa�s) and particles of corundum (see Table 1). Pitched blade impellers with four adjustable inclined plane blades made from construction steel (pitch angle � � 30°), pumping downwards were investigated in a fully baffled flat bottomed cylindrical agitated vessel (vessel diame- ter T � 300 mm, four baffles of width b � 30 mm, impeller 16 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 An Investigation of the Erosion Wear of Pitched Blade Impellers in a Solid-Liquid Suspension T. Jirout, I. Fořt This paper reports on a study of the erosion wear mechanism of the blades of pitched blade impellers in a solid-liquid suspension in order to determine the effect of the impeller speed n as well as the concentration and size of the solid particles on its wear rate. A four-blade pitched blade impeller (pitch angle � � 30°), pumping downwards, was investigated in a pilot plant fully baffled agitated vessel with a water suspension of corundum. The results of experiments show that the erosion wear rate of the impeller blades is proportional to n2.7 and that the rate exhibits a monotonous dependence (increase) with increasing size of the particles. However, the erosion rate of the pitched blade impeller reaches a maximum at a certain concentration, and above this value it decreases as the proportion of solid particles increases. All results of the investigation are valid under a turbulent flow regime of the agitated batch. Keywords: pitched blade impeller, erosion wear, solid-liquid suspension. Fig. 1: Radial profile of the leading edge of the worn blade of a pitched blade impeller diameter D � 100 mm, impeller off-bottom clearance C � 100 mm). The impeller speed was held constant n � 900 min�1 during an investigation of the influence of the suspension characteristics (see Table 1), and three levels of this quantity (900 min�1, 1050 min�1 and 1200 min�1) were selected for determining the dependence of the wear rate on the impeller speed (for average particle size dp � 0 29. mm and volumetric particle concentration cV � 5 %). The impeller speed was held within accuracy �1 % and the lowest level of this quan- tity corresponded for all investigated values of dp and cV to complete homogeneity of the suspension under a turbu- lent regime of flow of an agitated batch. The preliminary experiments were made visually in a perspex mixing vessel under the same conditions as for the erosion wear experi- ments. It follows from the results that, for all considered sizes and concentrations of the particles of corundum, there was 90 % homogeneity of the suspension at impeller speed n � 700 min�1. 3 Experiments During the experiments, the shape of the blade profile was determined from magnified copies of the worn impeller blades scanned to a PC (magnification ratio 2:1). The param- eters of the blade profile for the given time of the erosion pro- cess were determined from each curve of four individual worn impeller blades. The selected time interval from the very beginning of the each experiment was not to exceed the moment where the impeller diameter began to shorten. Then the values of the parameters of Eq. (1) – the wear rate con- stant k and the geometric parameter of the worn blade C – were calculated by the least squares method from the experi- © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 17 Acta Polytechnica Vol. 48 No. 4/2008 Fig. 2: Geometry of the pilot plant mixing vessel T � 300 mm, H T � 1, D T � 1 3, C D � 1, b T � 1 10b/T = 1/10 Fig. 3: Design of a pitched blade impeller with four inclined plane blades D � 100 mm, D0 20� mm, h � 20 mm, s � �100 0 05. . mm, � � �30 Indication of particle grain Particle density �s [kg�m �3] Average particle diameter dp [mm] Average volumetric particle concentrations in suspension cV [%] Corundum 120 3930 0.15 5, 7.5, 10 Corundum 90 3940 0.21 2.5, 5 Corundum 70 3940 0.29 2.5, 5 Corundum 60 3970 0.34 2.5 Table 1: Survey of the water-corundum suspensions used in the experiments mentally found profile of each worn blade at the given time interval t of the erosion process. Each curve was calculated from at least 15 points (H, R) with a regression coefficient better than R � 0 970. (see example in Fig. 4). The resulting values of parameters k and C were the average values calcu- lated from all individual values of these parameters for each blade. It can be mentioned that the chosen shape of the re- gression curve H f R� ( ) fits best to the experimental data among other possible two-parameter equations (e.g. an arbi- trary power function or the second power parabola). After the investigation of the shape of the worn blade, the weight of the blade was measured. All four blades were weighed on a scale with an accuracy � 5 mg, and the weight of the blade m related to its initial weight m0 (relative weight) was calculated at a given time (period) of the erosion process. The average value of the weight of the blade was calculated as the mean from all measured weights of the four individual blades moj or mj: m m m m o oj j j ( ) ( ) resp. � � 1 4 4 . (4) In this way the dependence of quantity m mo was ob- tained. At the same time the change in the shape of the particles was observed during the erosion process. Micro- scopic snap-shots of the corundum particles were made be- fore and after the process, and then their size distributions were compared. No change appeared on their surface (their edges did not become rounded and the corners did not disap- pear) after the experimental period came to an end (see example in Table 2), and their size distribution was also unchanged. 4 Results and discussion 4.1 Impeller speed vs. erosion rate Fig. 5 illustrates the time dependences of the relative weight of a worn impeller m m0 at three selected levels of im- peller speed n: m m C t o m n� �1 , . (5) Fig. 5 shows the values of parameter Cm,n for all levels of impeller speed calculated from the experimental data by the least squares method. The values increase with increasing impeller speed. This dependence can be described in a power form C nm n, .~ 2 7, R � 0 998. . (6) 18 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 1st blade 2nd blade y = 0,0873e -5,7109x R = 0,980 0 0.02 0.04 0.06 0.08 0.1 0.12 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 1-R 1 -H y = 0,0836e -6,1041x R = 0,966 0 0.02 0.04 0.06 0.08 0.1 0.12 0 0.1 0.2 0.3 0.4 0.5 0.6 1-R 1 -H 3rd blade 4th blade y = 0,0814e -5,8645x R = 0,968 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0 0.1 0.2 0.3 0.4 0.5 0.6 1-R 1 -H y = 0,0943e -5,5135x R = 0,979 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1-R 1 -H Fig. 4: Example of evaluating of the shape of a worn impeller blade: points – experimental values, curve – calculated regression Fig. 6 illustrates the time dependence of the wear rate con- stant k, and Fig. 7 depicts the time dependence of the geomet- ric parameter of the worn blade C at three impeller speed levels. While parameter k oscillates around a certain value throughout the erosion process, parameter C increases with time. Therefore the average value of parameter kav through- out the period when it is being determined, irrespective of the impeller speed value, can be considered as constant: � � �kav 3 8 015. . . (7) The worn blade geometric parameter C increases linearly with the duration of the erosion process t C C tn� . (8) Fig. 7 shows of the values of parameter Cn for all levels of impeller speed, calculated from the experimental data by the least squares method. The values increase with increasing im- peller speed. This dependence can be described in a power form C nn ~ .2 4, R � 0 939. . (9) © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 19 Acta Polytechnica Vol. 48 No. 4/2008 Indication of particle grain End of experiment Corundum 120 Corundum 90 Corundum 70 Corundum 60 Start of experiment Table 2: Microscopic snap-shots of corundum particles before and after a period of erosion process experiments These results confirm that the wear rate of a pitched blade impeller depends significantly on the impeller speed. This dependence is expressed in the overall relationship m m t� ( ), while the wear rate constant k does not exhibit any change within the tested impeller speed interval. The power at both dependences m m f no � ( ) and C f nn � ( ) exceeds two, so it does not depend only on the square of the velocity of the solid particles in a suspension, i.e. not only on their kinetic energy [4]. For metals, the value of the exponent at n can be consid- ered within the interval 2.3–3 [3]. It should only be pointed out that these correlations are valid for the given relative im- peller diameter D T � 1 3D/T = 1/3, and pitch angle � � �30 . 4.2 Suspension characteristics vs. erosion rate Figs. 8 and 9 illustrate the time dependences of the rela- tive weight of a worn impeller blade m mo for two investigated levels of average volumetric particle concentration in suspen- sion cV always at three levels of average particle diameter dp. These dependences can be expressed for all tested conditions in a linear form 20 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00 0 5 10 15 20 25 30 35 40 t [h] m /m 0 n � 900 min �1 n � 1050 min �1 n � 1200 min �1 Fig. 5: Time dependence of the relative weight of the impeller blade for different levels of impeller speed: points – experimental values, line – calculated linear regression 0.0 1.0 2.0 3.0 4.0 5.0 5 15 25 35 45 t[h] -k [- ] n � 900 min �1 n � 1050 min �1 n � 1200 min �1 Fig. 6: Time dependence of the wear rate constant for different levels of impeller speed m m C t o m d� �1 , . (10) It follows from the two Figures that the value of parameter Cm,d increases with increasing value of the average particle diameter. This dependence can be expressed in a power form for both levels of the average volumetric concentric time: C dm d p, ..� 0 0347 2 43, R cV� �0 999 2 5. ( . %) , (11) C dm d p, ..� 0 0117 1717, R cV� �0 899 5. ( %) . (12) From Eqs. (11) and (12) we can conclude that the erosion wear rate of a pitched blade impeller exhibits steeper de- pendence on time at a lower concentration among the concentrations investigated here. A deeper insight into the relation between the rate of erosion wear and the average vol- umetric particle concentration is provided by Fig. 10, which © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 21 Acta Polytechnica Vol. 48 No. 4/2008 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 10 20 30 40 t [h] C [- ] n � 900 min �1 n � 1000 min �1 n � 1200 min �1 Fig. 7: Time dependence of the geometric parameter of the worn blade for different levels of impeller speed 0.84 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 0 20 40 60 80 100 120 t [h] m /m 0 [- ] dp � 0.34 mm dp � 0.29 mm dp � 0.21 mm Fig. 8: Time dependence of the relative weight of the impeller blade for different levels of average particle diameter dp (cV � 2 5. %): points – experimental values, line – calculated linear regression shows the time dependence of the relative weight m mo at three levels of volumetric particle concentration cV for the same average particle diameter dp. This dependence can be expressed in a linear form 22 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 0 20 40 60 80 100 t [h] m /m 0 [- ] dp � 0.34 mm dp � 0.29 mm dp � 0.21 mm Fig. 9: Time dependence of the relative weight of an impeller blade for different levels of average particle diameter dp (cV � 5 %): points – – experimental values, line – calculated linear regression 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 0 20 40 60 80 100 t [h] m /m 0 [- ] cV � 5 % cV � 7.5 % cV � 10 % Fig. 10: Time dependence of the relative weight of an impeller blade for different levels of average particle volumetric particle concen- tration cV (dp � 015. mm) m m C t o m c� �1 , . (13) The slope in Eq. (13) Cm,c increases up to a certain critical level of the average particle concentration, and then it de- creases with increasing cV (see Table 3). This finding is in accordance with the general observation (Suchánek, 2006) that above some critical particle concentration the mutual in- teraction between striking and reflecting particles reduces their kinetic energy, and their influence on the metal surface of the impeller blade is reduced. Fig. 11 illustrates the time dependence of the wear rate constant k, and Figs. 12, 13 and 14 depict the time depen- dences of the geometric parameter of the worn blade C. While parameter k oscillates around a certain value during the ero- sion process, parameter C increases with time. Therefore, average values of parameter kav were calculated for each indi- vidual condition (dp and cV), always over the period in which they were determined (Table 4). It follows from this table that parameter kav varies in its absolute value within the limits 3.95–4.42. Therefore, we can assume that this parameter is independent of both the size and the concentration of the solid particles in a suspension, with its average value � � �kst 4 10 0 20. . . (14) When we compare the values kav (Eq. 7) and kst (Eq. 14), we can conclude that they show no significant difference within their variation. It follows from Figs. 12, 13 and 14 that the geometric pa- rameter of the worn blade increases linearly with the duration of the erosion process t C C tt� . (15) © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 23 Acta Polytechnica Vol. 48 No. 4/2008 Average volumetric particle concentration cV 5.0 7.5 10.0 Parameter Cm,c in Eq. (13) [h�1] 0.0013 0.0016 0.0013 Table 3: Dependence of parameter Cm,c on the average volumet- ric particle concentration (dp � 015. mm) 0 1 2 3 4 5 6 0 20 40 60 80 100 120 t [h] -k [- ] d cp V� �0.29 mm, 2.5 % d cp V� �0.21 mm, 2.5 % d cp V� �0.15 mm, %5 d cp V� �15 , 10 %0. mm d cp V� �, 5 %0.29 mm dp � 0.21 mm, 5 %cV � dp � 0.15 mm, .5 %c 7V � dp � mm0.34 , 2.5 %cV � Fig. 11: Time dependence of the wear rate constant for different properties of the suspension Average particle diameter dp [mm] Average volumetric particle concentration cV [%] kav [-] 0.15 5 �4.09 7.5 �4.08 10 �4.06 0.21 2.5 �4.01 5 �4.14 0.29 2.5 �4.42 5 �4.14 0.34 2.5 �3.95 Table 4: Mean time values of the wear rate constant kav In accordance with Eqs. (11) and (12), the power relation between parameter Ct and the average particle diameter is C dt p� 0 0717 2 34. . , R cV� �0 952 2 5. ( . %) (16) and C dt p� 0 0614 176. . , R cV� �0 936 5. ( %) . (17) Eqs. (16) and (17) confirm that the erosion wear rate of a pitched blade impeller depends significantly on the diame- ter of the solid particles in a suspension. Similarly as for the relative weight of the blade (Eq. 13), parameter Ct reaches a maximum value within the interval of the average volumetric particle concentrations investigated here (see Table 5). That is, at a higher concentration than cV � 7 5. %(dp � 015. mm), 24 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0 20 40 60 80 100 120 t [h] C [- ] dp � 0.34 mm dp � 0.29 mm dp � 0.21 mm Fig. 12: Time dependence of the geometric parameter of the worn blade for different levels of average particle diameter dp (cV � 2 5. %) t [h] 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0 20 40 60 80 100 C [- ] dp � 290. mm dp � 0.21 mm dp � 0.15 mm Fig. 13: Time dependence of the geometric parameter of the worn blade for different levels of average particle diameter dp (cV � 5 %) particles of corundum affect each other, with a simultaneous reduction in the interactions between particles and impeller blades. 5 Conclusions A two-parameter equation describing the shape of a worn blade during the erosion process of a pitched blade impeller in a solid-liquid suspension of higher hardness was investi- gated. It follows from the results of the experiments that the erosion wear rate is proportional to the 2.7th power of the impeller speed and that it exhibits a monotonous depend- ence (increase) with increasing size of the particles. However, the erosion rate of the pitched blade impeller reaches a maxi- mum at a certain concentration, and above this value it decreases as the proportion of solid particles in the agitated batch increases. List of symbols b baffle width, m C off-bottom impeller clearance, m C geometric parameter of the worn blade Cm constant in Eqs. (5), (10) and (13), h �1 Ct constant in Eq. (15), h �1 cV average volumetric concentration of solid parti- cles, m3�m�3 D impeller diameter, m Do hub diameter, m dp average diameter of solid particles, m H height of liquid from bottom of the vessel, m H dimensionless transversal coordinate of the profile of the worn blade h width of impeller blade, m k wear rate constant m weight of impeller blade, kg n impeller speed, s�1 R regression coefficient R dimensionless longitudinal (radial) coordinate along the radius of the impeller blade r longitudinal (radial) coordinate along the radius of the impeller blade, m s thickness of the impeller blade, m T vessel diameter, m t time, h y transversal coordinate along the width of the blade, m Greek symbols � pitch angle of the blade, deg �l density of liquid, kg�m �3 � dynamic viscosity, Pa�s Indices av average value j summation index n related to the concentration of solid particles d related to the diameter of the particles t related to time o initial value © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 25 Acta Polytechnica Vol. 48 No. 4/2008 0 0.05 0.1 0.15 0.2 0.25 0 20 40 60 80 100 t [h] C [- ] cV � 5 % cV � 7.5 % cV � 10 % Fig. 14: Time dependence of the geometric parameter of the worn blade for different levels of average volumetric particle concentration cV (dp � 015. mm) References [1] Fořt, I., Ambros, F., Medek, J.: Study of Wear of Pitched Blade Impellers, Acta Polytechnica, Vol. 40 (2000), No. 5–6, p. 11–14. [2] Fořt, I., Jirout, T., Cejp, J., Čuprová, D., Rieger, F.: Study of Erosion Wear of Pitched Blade Impeller in a Solid Liquid Suspension, Inzynieria Chemiczna i Proceso- wa, Vol. 26 (2005), p. 437–450. [3] Hutchings, I. M.: Wear by Particulates, Chem. Eng. Sci, Vol. 42 (1987), p. 869–878. [4] Suchánek, J.: Mechanisms of Erosion Wear and Their Meaning for Optimum Choice of a Metal Material in Practical Applications (in Czech), Proceedings of Scientific Lectures of Czech Technical University in Prague (Editor: K. Macek), No. 9, (2006) Prague (Czech Republic), 26 p. [5] Wu, J., Ngyuen, L., Graham, L., Zhu, Y., Kilpatrick, T., Davis, J.: Minimising Impeller Slurry Wear through Multilayer Paint Modelling, Can. J. Chem. Eng., Vol. 83 (2005), p. 835–842. [6] Wu, J., Graham, L. J., Noui-Mehidi, N.: Intensification of Mixing, J. Chem. Eng. Japan, Vol. 40 (2007), No. 11, p. 890–895. Doc. Ing. Tomáš Jirout, Ph.D. phone: +420 224 352 681 fax: +420 224 310 292 e-mail: Tomas.Jirout@fs.cvut.cz Doc. Ing. Ivan Fořt, DrSc. phone: +420 224 352 713 fax: +420 224 310 292 e-mail: Ivan.Fort@fs.cvut.cz Department of Process Engineering Czech Technical University in Prague Faculty of Mechanical Engineering Technická 4 166 07 Prague 6, Czech Republic 26 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 48 No. 4/2008 << /ASCII85EncodePages false /AllowTransparency false /AutoPositionEPSFiles true /AutoRotatePages /None /Binding /Left /CalGrayProfile (Dot Gain 20%) /CalRGBProfile (sRGB IEC61966-2.1) /CalCMYKProfile (U.S. Web Coated \050SWOP\051 v2) /sRGBProfile (sRGB IEC61966-2.1) /CannotEmbedFontPolicy /Error /CompatibilityLevel 1.4 /CompressObjects /Tags /CompressPages true /ConvertImagesToIndexed true /PassThroughJPEGImages true /CreateJobTicket false /DefaultRenderingIntent /Default /DetectBlends true /DetectCurves 0.0000 /ColorConversionStrategy /CMYK /DoThumbnails false /EmbedAllFonts true /EmbedOpenType false /ParseICCProfilesInComments true /EmbedJobOptions true /DSCReportingLevel 0 /EmitDSCWarnings false /EndPage -1 /ImageMemory 1048576 /LockDistillerParams false /MaxSubsetPct 100 /Optimize true /OPM 1 /ParseDSCComments true /ParseDSCCommentsForDocInfo true /PreserveCopyPage true /PreserveDICMYKValues true /PreserveEPSInfo true /PreserveFlatness true /PreserveHalftoneInfo false /PreserveOPIComments true /PreserveOverprintSettings true /StartPage 1 /SubsetFonts true /TransferFunctionInfo /Apply /UCRandBGInfo /Preserve /UsePrologue false /ColorSettingsFile () /AlwaysEmbed [ true ] /NeverEmbed [ true ] /AntiAliasColorImages false /CropColorImages true /ColorImageMinResolution 300 /ColorImageMinResolutionPolicy /OK /DownsampleColorImages true /ColorImageDownsampleType /Bicubic /ColorImageResolution 300 /ColorImageDepth -1 /ColorImageMinDownsampleDepth 1 /ColorImageDownsampleThreshold 1.50000 /EncodeColorImages true /ColorImageFilter /DCTEncode /AutoFilterColorImages true /ColorImageAutoFilterStrategy /JPEG /ColorACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /ColorImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000ColorACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000ColorImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasGrayImages false /CropGrayImages true /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true /GrayImageDownsampleType /Bicubic /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /GrayImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000GrayACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000GrayImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasMonoImages false /CropMonoImages true /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true /MonoImageDownsampleType /Bicubic /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict << /K -1 >> /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False /CreateJDFFile false /Description << /ARA /BGR /CHS /CHT /CZE /DAN /DEU /ESP /ETI /FRA /GRE /HEB /HRV (Za stvaranje Adobe PDF dokumenata najpogodnijih za visokokvalitetni ispis prije tiskanja koristite ove postavke. 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