Experience of Operating a Small Pilot-Scale Oxy-Fuel CFB Test Rig

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2 2 nd International Oxyfuel Combustion Conference September 12-16, 2011 Yeppoon, Queensland, Australia Experience of Operating a Small Pilot-Scale Oxy-Fuel CFB Test Rig Tomasz CZAKIERT, Marcin Klajny, Waldemar MUSKALA, Grzegorz KRAWCZYK, Pawel BORECKI, Michal GANDOR, Sylwia JANKOWSKA, Wojciech NOWAK

3 NCR&D Project Advanced Technologies for Energy Generation: Oxy-combustion technology for PC and FBC boilers with CO 2 capture Budget: ~ 25 mln USD Period: 5 years Research on kinetics and mechanisms of oxy-fuel combustion Bench-scale experiments Small pilot-scale investigations (0.1MW th CFB, 0.2MW th PCFB, 0.5MW th PC) Oxygen production issues (incl. mobile ASU) CO 2 capture issues (incl. mobile CCU) General modeling work Feasibility study for a full chain demo-scale oxy-fuel plant with CCS Czestochowa University of Technology Silesian University of Technology Wroclaw University of Technology Institute of Power Engineering Institute for Chemical Processing of Coal Foster Wheeler Energia Polska PKE Lagisza Power Plant PGE Turow Power Plant Eurol Innovative Technology Solutions Academies R&D Centers Industry 3

4 Experimental 4

5 RESULTS PRESSURE FLUCTUATIONS The strongest pressure fluctuations in combustion chamber were recorded at the level P2 The lightest pressure fluctuations were measured at the levels P7-P9 The broadest range of changes in pressure was registered in loopseal at the level P10 5

6 RESULTS PRESSURE LOOP Basu P., Fraser S.A., Circulating Fluidized Bed Boilers, Pressure loop remains in agreement with typical pressure balance around CFB loop (Basu P., Fraser S.A., 1991) Total pressure drop in combustion chamber (P2-P9) is kept at level of 2500Pa Pressure drop in grid (P1-P2) is estimated at 300Pa Pressure drop in cyclone (P9-P13) is estimated at 1300Pa 6

7 RESULTS SOLIDS DISTRIBUTION Kunii D., Levenspiel O., Fluidization Engineering, Five zones along height of combustion chamber can be distinguish (Kunii D., Levenspiel O., 1991) Significant difference (ca. 25 times) between grid zone and upper part of furnace can be observed Very uniform profile above level of secondary gas distribution points can be seen Lean phase in freeboard contains both fines and coarse particles 7

8 RESULTS TEMPERATURE PROFILE Ranges of changes in temperature are much shorter compared to those of pressure Data distributions are lower than 1% of mean values Slight increase in temperature in bottom zone (T2-T5) can be observed Very even profile in upper part of furnace (T6-T9) can be seen T1: ~570K & T15: ~555K 8

9 CALCULATIONS C -> CO, CO 2 S -> SO 2, SO 3, H 2 S N -> NO, NO 2, N 2 O, NH 3, HCN Conversion ratio of combustible sulfur contained in fuel to SO 2 Molar ratio of S (fixed in SO 2 ) / C (fixed in CO 2 & CO) in flue gas Molar ratio of combustible S / C in fuel 9

10 RESULTS CARBON CONVERSION C -> Carbon monoxide (CO) C -> Carbon dioxide (CO 2 ) Progress in burn-out of combustible matter can be observed High value of CR C (~70%) at the level of FG1 (0.43m); high fraction of CO Further fuel burn-out & oxidation of CO between FG1-FG2 ( m) Further carbon conversion to CO 2 & stable value of CR C->CO Estimation of C unburnt fuel & C unburnt CM on the basis of carbon molar balance in the circulation loop 10

11 RESULTS SULFUR CONVERSION S -> Sulfur dioxide (SO 2 ) S -> Sulfur trioxide (SO 3 ) S -> Hydrogen sulfide (H 2 S) CR S ~ CR C at the level of FG1, distribution of C & S within volatile matter and char is uniform Stable value of CR S->H2S along the height of combustion chamber Residual impurity of SO 3 in upper part of furnace Decrease value of CR S->SO2+SO3, bonding of sulfur oxides with Ca and Mg both contained in fuel-ash High value of total CR S (~90%) S fuel unburnt & S CM unburnt 11

12 RESULTS NITROGEN CONVERSION N -> Nitrogen monoxide (NO) N -> Nitrogen dioxide (NO 2 ) N -> Nitrous oxide (N 2 O) N -> Ammonia (NH 3 ) N -> Hydrogen cyanide (HCN) Low value of total CR N (~17%) 2 main N-based compounds: N 2 O & NO Residual impurity of NO 2 along the height of combustion chamber Considerable & stable fraction of HCN 1 short peak of NH 3 appears temporary in bottom part of furnace Reduction of (NO?) to N 2 in upper part of furnace; NO + C = 0.5N 2 + CO or NO + CO = 0.5N 2 + CO 2? Reduction of NO to (HCN?); CR N->NO, CR N->HCN, Hydrocarbons conc. ; NO + C x H y = HCN +? N unburnt fuel & N unburnt CM 12

13 CONCLUSIONS The small pilot-scale Oxy-Fuel CFB facility operates smoothly under the investigated conditions. A significant difference (ca. 25 times) in solids concentration between the grid zone and the upper part of the furnace was observed. Otherwise, a very uniform density of gas-solids phase was found above the level of secondary gas distribution points. A slight increase in temperature was observed in the bottom zone below the level of SG distribution points, whereas, very even profile of temperature was noticed in the upper part of the furnace. The Conversion Ratio of C -> CO, CO 2 ; S -> SO 2, SO 3, H 2 S; N -> NO, NO 2, N 2 O, NH 3, HCN was applied to the analysis of progress in fuel combustion. High value of CR C (~70%) was found just at the level of FG1 (~0.4m above the grid) and further oxidation of both C and CO above the level of SG was observed. High value of total CR S (~90%) was noticed. Stable value of CR S->H2S along the height of combustion chamber was observed. Residual impurity of SO 3 & bonding of sulfur oxides with fuel-ash compounds were found in the upper part of the furnace. Low value of total CR N (~17%) & two main N-based flue gas compounds (NO, N 2 O) were noticed. Residual impurity of NO 2 and considerable fraction of HCN along the height of combustion chamber were found. Reduction of NO in the upper part of the furnace was observed. 13

14 THANK YOU FOR YOUR ATTENTION 2 nd International Conference on Oxyfuel Combustion September 12-16, Yeppoon, Queensland, Australia