Sensitivity Analysis of 100 MWth Chemical Looping. Combustion Combined Cycle (CLC-CC) Plant. Based on Fuel Cost

Transcription

1 Sensitivity Analysis of 100 MWth Chemical Looping Combustion Combined Cycle (-CC) Plant Based on Fuel Cost Young Cheol Park, Tai-yong Lee*, and Ho-Jung Ryu Korea Institute of Energy Research, *Hongik University Abstract - In this study, sensitivity analysis of 100 MWth chemical looping combustion combined cycle (-CC) plant based on fuel cost were performed. By performance analysis, net efficiency of natural gas/syngas fueled -CC plant was 53-54%, corresponding to previous research. We used Chemical Engineering Plant Cost Index and Guthrie method to evaluate plant cost. For syngas fueled -CC plant, the plant cost was higher since lower heating value (LHV) of syngas was lower than that of natural gas and cost of electricity (COE) was also higher since the cost of syngas was higher than that of natural gas. By sensitivity analysis, it was shown that the cost of syngas should be less than 5.3 $/GJ in order to make COE lower than 5.8 c/ /kwh which was COE of natural gas -CC plant. Keywords: Chemical looping combustion, Sensitivity analysis, Fuel cost, Natural gas, Syngas, Aspen Plus 1. Introduction Chemical looping combustion () technology using natural gas (NG) or syngas has been paid attention as a next generation low-emission and high-efficiency power generation technology since it recovers CO 2 without additional separation equipments and does not generate thermal-nox caused by direct flame [1]. For NG-fired power plant, it was inevitable to decrease 9-27% of power generation efficiency and to increase the cost of electricity (COE) times in order to separate and recover highly-concentrated carbon dioxide [2,3]. For technology, thermal efficiency is similar to the next generation power generation technology [4-6], CO 2 emission is low and the flue gas contains CO 2 and H 2 O so that carbon dioxide could be recovered after condensation [7]. In this study, we performed sensitivity analysis of 100 MWth combined cycle (-CC) plant based on fuel cost. -CC plant was first simulated using a commercial simulator and economic analysis was performed. We used fluidized-bed reactors and NiO/Bentonite oxygen carriers which were reported by Ryu et al. [8]. The COE was finally calculated based To whom all correspondence should be addressed. hjryu@kier.re.kr

2 on fuel cost and the optimal syngas cost was suggested. 2. Performance analysis of 100 MWth -CC plant In -CC plant, both gas turbine and steam turbine were used. We compared the performance of the proposed power plant with 700 MWth -CC plant [9]. To have fair comparison, we set oxidation temperature 1200 o C, reduction temperature 980 o C and the same air flow rate. Based on the fuels oxidation reaction was the same but reduction reaction was different, so the solid inventory and solid circulation rate were different. We assumed the inlet pressure of NG was 8 bar and that of syngas was 18 bar, the outlet pressure of Integrated Gasification Combined Cycle (IGCC). The -CC plant consists of air compressor, air preheater, fuel pre-heater, reactors, gas turbine, heat recovery steam generator (HSRG), steam turbine, and CO 2 compressor. Through HRSG, 60 bar high-pressure steam and 5 bar intermediate-steam were produced. The simulation results were compared with 700 MWth -CC plant [9]. The results were listed in Table 1. The plant efficiency based on fuel lower heating value (LHV) was similar to the reference [9] which was used NG as a fuel. Table 1. Performance analysis of -CC plant (MW) NG [9] NG Syngas fuel flow 15 kg/s 2.04 kg/s 7.81 kg/s Fuel LHV Air Turbine work % % % CO 2 Turbine work % % % Steam Turbine work % % % Compressor work % % % CO 2 compression % % % LNG compression % Net eff % % % 3. Economic analysis The -CC plant cost was calculated using Guthrie method [10]. The dimensions of the reactors were determined using MS Excel program developed by Ryu and Jin [11]. The dimensions of reactors according to fuels were shown in Fig. 1. The volume increased 1.23 times when syngas was used as a fuel. The cost of gas turbine and steam turbine was 192 $/kwe and 570 $/kwe, respectively [12]. The cost of CO 2 compression system was 400 $/kwe [13] including compression, separation and auxiliary. The total cost and the specific cost ($/kwe) were listed in Table 2 and Table 3, respectively. The specific cost of the proposed system was similar to that of Consonni et al. [12] s Fired -CC plant. Operating costs

3 include NiO/Bentonite particle cost and fuel cost. NiO/Bentonite cost was 4.8 $/kg [14] and the life-time of the sorbent was assumed to 6 months. The cost of NG was 5.4 $/GJ [12] and that of syngas was 8.22 $/GJ [15]. The operating costs for both NG and syngas fueled - CC plant were summarized in Table 4. Column Diameter [m] Oxidizer Reducer System Volume Ratio [-] LNG Syngas 0.0 LNG Syngas Fig. 1. Variation of dimensions of reactors according to fuels. Table MWth -CC plant equipment cost according to fuels (1,000 $) NG Syn. Gas Pressure Vessels 1,500 1,886 Heat Exchangers 10,825 11,036 Compressors + CO 2 compression system Gas turbine + steam turbines 23,816 24,351 Total 36,807 38,224 Table 3. Specific cost ($/kwe) (*exchange rate : 1.2 USD/euro) Consonni et al. [12] present work Unfired Fired NG-CC PO-CA SC-CA (NG) (Syngas) Specific cost * NG-CC: Natural gas combined cycle, PO-CA: Partial oxidation-chemical absorption, SC- CA: Semi-closed cycle chemical absorption, Unfired: natural gas is fed only to the system, Fired: the vitiated air is supplementary fired to reach gas turbine inlet temperatures raging o C.

4 Table 4. Operating costs according to fuels Unit NG Syngas NiO/Bentonite Unit Cost $/kg 4.8 # of Replacement /yr 2 Sorbent Cost 1,000 $/yr 925 1,165 Fuel Unit Cost $/GJ Fuel Cost 1,000 $/yr 15,430 23,573 Total 1,000 $/yr 16,355 24,738 COE for capital cost and for operating cost was calculated by following equations: (100)(Cost)(LCF) COE Capital, c/kwh / = (11) (Power)(365)(24)(CF) (100)(Cost)(LCF) COE Production, c/kwh / = (12) (Power)(365)(24)(CF) where power was kw, cost was $, CF and LCF was 0.8 and 0.15 [12], respectively. COE Total was summarized in Table 5. When syngas was used as a fuel, COE was higher than NG was used as a fuel. Table 5. Cost of electricity(coe) ( c/ /kwh) Consonni et al. [12] NG-CC PO-CA SC-CA Unfired Fired (NG) present work (Syngas) COE Capital COE Production COE Total Sensitivity analysis according to fuel cost The COE according to syngas cost was shown in Fig. 2. When syngas cost was below 5.3 $/GJ, the COE was below 5.8 c/ /kwh. In this study the NG cost was 5.4 $/GJ, so COE could be low when syngas cost was lower than NG cost. In other words, syngas cost should be reduced about 35% of current cost, 8.22 $/GJ in order to maintain COE of syngas-fueled

5 -CC plant as that of NG-fueled -CC plant. 9 8 COE Total, c/kwh Syngas, $/GJ Fig. 2. COE according to the syngas price. 5. Conclusion 100 MWth -CC plant was simulated using a commercial simulator based on fuels such as NG and syngas. The plant efficiency was 53.2% in NG, 54.1% in syngas based on fuel LHV. The reactor volume was increased 1.23 times when syngas was used as a fuel. The COE of NG-fueled -CC plant was 5.8 c/ /kwh and that of syngas-fueled -CC plant was 8.0 c/ /kwh. By sensitivity analysis, the syngas cost should be less than 5.3 $/GJ in order to maintain COE around 5.8 c/ /kwh. Acknowledgement This work was supported by Ministry of Knowledge Economy (MKE) through Electric Power Industry Technology Evaluation & Planning Center (ETEP). References [1] Ryu, H. J.: "CO 2 -NOx free chemical- looping combustion technology", KOSEN report, [2] Akai, M., Kagajo, T. and Inoue, M., "Performance Evaluation of Fossil Power Plant with CO 2 Recovery and Sequestering System", Energy Convers. Mgmt., 36(6), (1995). [3] Kimura, N., Omata, K., Kiga, T., Takano, S., and Shikisma, S., "The Characteristics of Pulverized Coal Combustion in O 2 /CO 2 Mixture for CO 2 Recovery", Energy Convers. Mgmt., 36(6), (1995). [4] IEA Greenhouse Gas R&D Programme Report, "Greenhouse Gas Emissions from Power

6 Stations", (2000), available on [5] IEA Greenhouse Gas R&D Programme Report, "Carbon Dioxide Capture from the Power Stations", (2000), available on [6] Wolf, J., Anheden, M. and Yan, J., "Comparison of Nickel- and Iron-based Oxygen Carriers in Chemical-Looping Combustion for CO 2 Capture in Power Generation", Fuel, 84(7), (2005). [7] Ishida, M. and Jin, H., "A New Advanced Power-Generation System Using Chemical- Looping Combustion", Energy, 19(4), (1994). [8] Ryu, H. J., Jin, G. T., Jo, S. H., and Bae, D. H., "Comparison of Operating Conditions for Natural Gas Combustion and Syngas Combustion in a 50kWth Chemical-Looping Combustor", Theories and Applications Chem. Eng., 12(2), 259(2006). [9] Naqvi, R.: "Analysis of Natural Gas-Fired Power Cycles with Chemical Looping Combustion for CO 2 Capture", Ph. D. Dissertation, Norwegian University of Science and Technology, Trondheim(2006). [10] Biegler, L. T., Grossmann, I. E. and Westerberg, A. W., Systematic Methods of Chemical Process Design, 1st ed., Prentice-Hall, Upper Saddle River, NJ(1997). [11] Ryu, H. J. and Jin, G. T., "Conceptual Design of 50kW thermal Chemical-Looping Combustor and Analysis of Variables", Energy Engg. J., 12(4), (2003). [12] Consonni, S., Lozza, G., Pelliccia, G., Rossini, S., and Saviano, F., "Chemical-Looping Combustion for Combined Cycles with CO 2 Capture", Journal of Engineering for Gas Turbines and Power, 128(3), (2006). [13] Chiesa, P. and Consonni, S., "Natural Gas Fired Combined Cycles with Low CO 2 Emissions", Journal of Engineering for Gas Turbines and Power, 122(3), (2000). [14] Lyngfelt, A., Kronberger, B., Adanez, J., Morin, J.-X., and Hurst, P., "The Grace Project: Development of Oxygen Carrier Particles for Chemical-Looping Combustion. Design and Operation of 10 kw ", 7th International Conference on Greenhouse Gas Control Technologies, September, Vancouver(2005). [15] Spath, P., Aden, A., Eggeman, T., Ringer, M., Wallace, B., and Jechura, J., : "Biomass to Hydrogen Production Detailed Design and Economics Utilizing the Battelle Columbus Laboratory Indirectly-Heated Gasifier", Technical Report, May, NREL/TP (2005).