Closed-cycle for environmental protection in thermal power plants NATO Advanced Study Institute on Energy Security 4-11 October 2015, Antalya, Turkey Faculty of Power Engineering and Power Machines, Department of Thermal and Nuclear Power Engineering Closed-cycle for environmental protection in thermal power plants Denitza Zgureva, Silviya Boycheva Motivation Syntheses of zeolites from fly ashes The expected growth of the consumption of electricity between 2010 and 2040 is 56 %. Still the coal combusting TPP are the major producer of energy. Our investigation program is devoted to the realization of closed-cycle for environmental protection in TPP by the conversion of lignite coal fly ash into synthetic zeolites and their applications in the flue gas cleaning systems. Zeolitization of FA from Bulgarian lignite coal was carried out by two-stage fusion-hydrothermal syntheses with NaOH as an alkaline activator. FA SiO2 wt% Al2O3 wt% Fe2O3 wt% MgO wt% SO3 wt% CaO wt% ρ kg/m3 Fraction AES 46.58 23.26 14.73 0.81 2.49 3.01 1940 d50<0.045 mm МE 2 52.66 23.37 8.72 2.75 2.40 5.75 3070 d100=0.125-0.250mm Production of greenhouse gases Capturing of CO2 Synthesis of high porous zeolites Production of fly ash residue COALS FA major constituents: 52-90 % aluminosilicates Post-combustion capture for existing TPP Global warming Molecular sieve Mixed amorphous-crystalline structure in a ratio of 43/57 for ME 2 and 65/35 for AES. Raw materials Synthetic zeolite for analyses Fusion Magnetic stirring FA 5g 550 oC, 1 h 16 h NaOH 10g From FA to Na-X zeolite Washing and drying Hydrothermal activation 90 oC, 2-20 h 105 oC, 1 h Zeolites - the best adsorbents for post-combustion carbon capture systems Fundamental process design parameters Adsorption capacity - surface and porosity Selectivity Mass transfer kinetics Heat of adsorption BET analyses of the synthesized materials Adsorption of carbon dioxide onto synthetic zeolites Micromeritics Instrument Corporation TriStar II 3020 3.02 TriStar II 3020 Version 3.02 Sample: Sample AES 4 h Started: 27/08/2015 14:42:17 Analysis Adsorptive: CO2 Completed: 27/08/2015 17:56:29 Analysis Bath Temp.: 273.15 K Sample Mass: 0.0994 g Warm Free Space: 9.5825 cm³ Measured Cold Free Space: 10.1019 cm³ Equilibration Interval: 5 s Saturation Pressure (kPa) 3485.6769 BET range limit p/p0=0.01-0.08 Liquid Nitrogen Т = -198 оС Gaseous Nitrogen p0 = 101.238 kPa Sample SBET, m2/g Smicro, Vmicro, cm3/g Vmeso, cm3/g Yield of Na-X based on FA aluminosilicates, % AES 2 h 310.61 186.55 0.083 0.158 57.03 AES 4 h 387.75 242.99 0.098 0.173 71.19 AES 21 h 379.20 253.99 0.108 0.153 69.62 ME2 2 h 176.17 94.82 0.039 0.124 29.71 The Na-X zeolite can be synthesized by lignite coal ash with different composition and structure through controllable two stage mechanism. The highest specific surface area SBET = 387.75 m2/g is obtained for Na-X zeolite synthesized by FA from TPP AES for 4 h activation. Adsorption capacity of FA zeolites is measured through experimental adsorption isotherms and it reaches 125.40 mgCO2/g. Technical University of Sofia, Department of Thermal and Nuclear Power Engineering, Blvd. Kl. Ohridsky 8, 1000 Sofia, Bulgaria, e-mails: dzgureva@gmail.com; sboycheva@tu-sofia.bg