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Tadeusz Chmielniak, Daniel Czaja and Sebastian Lepszy

References [1] Zander L., Zander Z.: Plate heat exchange designing. Instalacje sanitarne 2(2003), 7, 27-30 (in Polish). [2] Chmielniak T., Czaja D., Lepszy S.: A thermodynamic and economic comparative analysis of combined gas-steam and gas turbine air bottoming cycle. In: Proc.ECOS 2012 - 25th Int. Conf. on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Perugia, June 26-29, 2012, 34-53. [3] Gut J. A.W, Pinto Jose M.: Modeling of plate heat exchangers with

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Daniel Czaja, Tadeusz Chmielnak and Sebastian Lepszy

References [1] Chmielniak T., Czaja D., Lepszy S.: A thermodynamic and economic comparative analysis of combined gas-steam and gas turbine air bottoming cycle. In: Proc. 25th Int. Conf. Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2012, Jun 26-29, 2012, Perugia. [2] Intecteam, JV-Team for Planning, Construciton, Service, Trading in the Energy Business. Budget offer Combined Cycle Power Plant. Würzburg; website: www.intecteam.eu. [3] Czaja D., Chmielniak T., Lepszy S

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Tadeusz Chmielniak, Sebastian Lepszy and Daniel Czaja

-and-steam power station on the characteristics of efficiency. In: Proc. 4th International Science and Technology Conference, Expo-Ship 2006. Research papers number 10(82) of the Marine University in Szczecin. Korobitsyn M.: Industrial applications of the air bottoming cycle systems assessment department. Netherlands Energy Research Foundation, Energy Conversion and Management 43 (2002), 1311-1322. Yousef S, Najjar H., Zaamout M.S.: Performance analysis of gas turbine air-bottoming combined system. Energy Conversion and

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Forestry Studies

Metsanduslikud Uurimused; The Journal of Estonian University of Life Sciences

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Janusz Kotowicz and Marcin Job

References [1] K otowicz J.: Combined Cycle Power Plants. Kaprint, Lublin 2008 (in Polish). [2] K otowicz J., J anusz K.: Manners of the reduction of the emission CO 2 from energetic processes. Rynek Energii 68 (2007), 1, 10–18 (in Polish). [3] L iu C.Y., C hen G., S ipöcz N., A ssadi M., B ai X.S.: Characteristics of oxy-fuel combustion in gas turbines. Appl. Energ. 89 (2012), 387–394. [4] Z hanga N., L ior N.: Two novel oxy-fuel power cycles integrated with natural gas reforming and CO 2 capture. Energy 33 (2008

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Boris Bielek, Daniel Szabó and Milan Lavrinčík

parameters of facade elements for the building of Panorama City Bratislava, SUT - Faculty of Civil Engineering, Bratislava, 2014. Brager, G. S. - De Dear, R. (2000) A Standard for Natural Ventilation. Ashrae Journal, 2000. Brown, G. Z. - Kline, J. - Livingston, G. - Northcutt, D. - Wright, E. (2004) Natural ventilation in Northwest Buildings. Oregon: University of Oregon USA, 2004. CEN/TC 156. (2004) Ventilation for buildings - Calculation methods for the determination of air flow rates in buildings including infiltration

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Daniel Szymański, Julita Dunalska, Michał Łopata, Izabela Bigaj and Rafał Zieliński

-442. Tadajewski A., 1966, Chemizm osadow dennych jeziora Sukiel i uwagi o jego faunie dennej (Chemistry of lake Sukiel sediments and remarks on its bottom fauna), Zesz. Nauk. WSR Olsztyn. 21(4): 689-710 (in Polish, English summary). van Hullebusch E., Auvray F., Deluchat V., Chazal Ph.M., Baudu M., 2003, Phosphorus fractionation and short term mobility in the surface sediment of a shallow polymictic lake treated with low dose of alum (Courtille lake, France). Water Air Soil Pollut. 146(1-4): 75-91.

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Yan-Na Liu and Song Xiao

-grade heat. Renew. Sust. Energ. Rev. 14(2010), 3059-3067. [24] Bianchi M., De Pascale A.: Bottoming cycles for electric energy generation: parametric investigation of available and innovative solutions for the exploitation of low and medium temperature heat sources. Appl. Energ. 88(2011), 1500-1509. [25] Chacartegui R., Sánchez D., Muńoz J.M., Sánchez T.: Alternative ORC bottoming cycles for combined cycle power plants. Appl. Energ. 86(2009), 2162-2170. [26] Lai N.A., Wendland M., Fischer J.: Working fluids for high

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Adam Fic, Jan Składzień and Michał Gabriel

References [1] M ikielewicz D., M ikielewicz J.: Utilisation of bleed steam heat to increase the upper heat source temperature in low-temperature ORC . Arch. Thermodyn. 32 (2011), 3, 57–71. [2] C hmielniak T., L epszy S., C zaja D.: The use of air-bottoming cycle as a heat source for the carbon dioxide capture installation of a coal-fired power unit . Arch. Thermodyn. 32 (2011), 3, 89–103. [3] C eliński Z., S trupczewski A.: Fundamentals of Nuclear Power , PWN, Warsaw 1984 (in Polish). [4] Y ildis B., K azimi M.S.: Efficiency

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Stanisław Cierpisz

Abstract

The beneficiation process of fine coal in jigs consists of two phases: stratification of coal grains in the bed according to their density and then splitting the stratified material into the product and the discharged refuse. At first, during subsequent water pulsations induced by opening and closing of air valves, the stratification of coal grains takes place due to varied velocity of their upward and downward movement.

Grains of low density migrate to upper layers and grains of high density migrate to lower layers of the bed. The material travels horizontally on a screen along the jig compartment with the flow of water.

The stratification of grains due to their density is not perfect, because the velocity of their upward and downward movement depends in part on their diameter, shape and the way in which the material loosens within a given pulsation cycle. The distribution of coal density fractions in the bed, characterized by the imperfection factor I, has been investigated by many researchers. The imperfection factor I is defined as the ratio of the probable error Ep and the separation density ρ50 (I = Ep50).

The distribution of coal density fractions for an ideal and a real stratification process was compared. The maximum mass of the product of the desired quality (ash content) can be achieved for the ideal process when the imperfection I = 0. The stratified bed is then, in the end part of the jig, split into the product which overflows the end wall of the compartment and the refuse (or middlings) discharged through the bottom gate. The separation density (cut point) is established by the tonnage of the discharged bottom product (opening of the discharge gate). The separation density depends also on the tonnage of raw coal feeding the jig, and its washability characteristics. The impact of variations in the separation density on product parameters has been analysed. The mass of the product is always greater when the separation density is constant over a given period of time – even if in spite of its variations the process renders the same average ash content. Hence, the conclusion is to stabilise the separation density at the desired value as accurately as possible. The analysis was performed for raw coal washed in a three-product jig at the separation densities of 1.5 and 1.8 g/cm3. Percent contents (in brackets) of density fractions in raw coal were: <1.35 g/cm3 (40%), 1.35–1.50 g/cm3 (12%), 1.50–1.65 g/cm3 (4%), 1.65–1.80 g/cm3 (4%), 1.80–1.95 g/cm3 (12%, >1.95 g/cm3 (30%) (average ash in raw coal was 35.5%). In the analysis, an increase in the imperfection by 0.02 resulted in the decrease of the product tonnage by ΔQc = 1.0%. In this case, separation densities were set to ensure the same ash content in products (for I = 0 the change in tonnage was accepted at ΔQc = 0). The simulation analysis presented in the paper focused on the impact that fluctuations in separation density have on the economic effects of a jig operation. The influence of the separation density fluctuations on the product tonnage turned out to be nonlinear; for ±0.04 g/cm3 (control system with the radiometric density meter) the decrease in the product tonnage was ca. 0.5 % and for ±0.12 g/cm3 it was ca. 5.0% (control system with a float). The above results indicate that the operation of a refuse discharge system in a jig plays an important role in the final results of coal separation process defined in terms of tonnage and quality of the product.