Experimental and Analytical Results on H 2 SO 4 and SO 3 Decomposer for IS Process Pilot Plant

Transcription

1 Experimental and Analytical Results on H 2 SO 4 and SO 3 Decomposer for IS Process Pilot Plant A. Terada, Y. Imai, H. Noguchi, H. Ota, A. Kanagawa, S. Ishikura, S. Kubo, J. Iwatsuki, K. Onuki and R. Hino Nuclear Energy Basic Engineering Research Sector Japan Atomic Energy Agency 1

2 Thermochemical Iodine-Sulfur (IS) Process 67J Hydrogen Nuclear Heat Oxygen 1 H 2 24J 76J O O C 900 C 1 H O 2 33J Rejected H 2 SO 2HI 4 + I 2 SO 2 +H 2 O I 2 I (Iodine) Circulation developing IS process aiming to realize nuclear hydrogen production 2H I I 2 100J Heat C + + H 2 O + H 2 O H 2 SO 4 SO 2 +H 2 O S (Sulfur) Circulation SO 2 + H 2 O Hydrogen iodide (HI) Water Sulfuric acid (H 2 SO 4 ) decomposition Bunsen decomposition (endothermic) reaction (endothermic) IS Process - H 2 is produced by thermal decomposition of HI at ca. 400, and O 2 is produced by thermal decomposition of H 2 SO 4 below 900. (Pyrolysis of water; Heat more than 4000) - Iodine and sulfur compounds are used as recycling materials under thermochemical close cycle 2

3 Next Step : Pilot Test (JAERI s Plan) On the basis of the hydrogen production test results and know-how obtained with the bench-scale test apparatus and other R&Ds Bench-scaled Test Pilot Test HTTR Test nuclear demonstration Hydrogen production rate 0.03 m 3 /h 30 m 3 /h 1000 m 3 /h Heat supply Electrical heater Heat exchanger with helium gas (Electrical heater 0.4MW) Heat exchanger with helium gas (Nuclear heat 10MW) Material of chemical reactors Glass Industrial material (SiC, coated) Industrial material Pressure of chemical process Time Atmospheric pressure FY High pressure (up to 2MPa) FY (under planning) High pressure (up to 2MPa) FY (under planning) To confirm continuous hydrogen production under simulated HTGR operations and fabricability of components, and to establish technology base for realizing high thermal efficiency more than 40%. 3

4 Flow Diagram of IS Process Pilot Plant ( tentative ) Existing He circulation facility (He Loop) He gas(4mpa) IS Process Pilot Test Plant (2MPa) Condenser H 2 O 30Nm 3 /h H Condenser Electric Heater 400kW 150 He Circulator Cooler SO 3 SO 3 Decomposer 850 H 2 SO 4 Decomposer 500 He gas SO 2 O 2 O 2 H 2 SO 4 / HIx (HI+I 2 ) Separator I 2 Bunsen Reactor 120 Steam H 2 I 2 HI HI Decomposer 450 Steam Steam Generator He gas HI Distillation Column Steam 250 H 2 SO 4 Concentrator Purifier Purifier Electro-Dialyzer Sulfuric Acid (H 2 SO 4 ) Decomposition HI Decomposition Conceptual design (system, components) : taking into account of effective heat recovery including efficient HI concentration by using electro-dialysis, so as to increase system efficiency. 4

5 Concept of H 2 SO 4 Decomposer for Pilot Test Plant The concept of the H 2 SO 4 decomposer is a counterflow type heat-exchanger made of SiC, which works as an H 2 SO 4 evaporator. Items Thermal Rating He Inlet / Outlet Temp. Process Inlet / Outlet Temp. He Pressure Process Pressure He Flow Rate Process Flow Rate Conditions 82.7 kw 710 / / MPaG 2 MPaG kg/s kg/s Thermal insulation He inlet 0.7m H 2 SO 4 inlet SO 3 +H 2 O outlet He outlet SiC block 3.1m 1.5m 0.25m H 2 SO 4 outlet He inlet SiC block Gasket (Au) He outlet H 2 SO 4 inlet Ref) H. Ota et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE H. Ota et al., 2005 Ibaraki Meeting of the Japan Society of Mechanical Engineers, Hitachi-taga, Ibaraki, Japan, September 9,

6 Structure Analysis of H 2 SO 4 Decomposer (1/2) Temperature () He H 2 SO 4 Sub-cooled region Superheat region Distance from SiC block inlet (m) Axial Temperature Distribution Ref) H. Ota et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

7 Structure Analysis of H 2 SO 4 Decomposer (2/2) Heat Transfer and Stress Analysis of SiC Block Max.T=250and P=2MPa : Max. stress=114mpa Average tensile strength of SiC = 250 MPa 1/4 model of SiC block H 2 SO 4 channel Dryout level Max. stress 114 MPa He channel Temperature distribution H 2 SO 4 channel He channel Stress distribution (thermal stress + static stress) Ref) H. Ota et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

8 Test Fabricated SiC Block Assembly - Mock-up Model- Upper SiC block ( m We confirmed fabricability of the SiC block assembly. Ref) H. Ota et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE H. Ota et al., 2005 Ibaraki Meeting of the Japan Society of Mechanical Engineers, Hitachi-taga, Ibaraki, Japan, September 9,

9 Seal Performance Test with Mock-up Model of H 2 SO 4 Decomposer Objectives To confirm applicability of a gold seal for boundary between sulfuric acid (liq. or gas) and helium Gold cap gasket Test method Vacuum furnace Gasket Seal performance test Metal O-ring SiC block Water press. He gas press. Leak test model Attachment of gold cap gaskets 19mm) SiC block Flange Test condition 3 heat cycle up to 500 Outer press. :Vacuum Inner press. :4MPa He leak detector Test results SiC block (120mm50mmt) Helium leak rate was 7.5x10-8 Pa m 3 /s at the connection of SiC blocks, which was much less than the LWR rubber seal standard of Ref) H. Ota et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

10 H 2 SO 4 Thermal-Hydraulic Test Loop Boiling heat transfer test loop Heat transfer measurements and flow-visualization Max. flow rate : 2.5L/min Component test loop Performance & integrity of H 2 SO 4 components Max. flow rate : 20 L/min Cooler Glass lining piping LE TE FE PE Level gauge Thermocouple Flow meter Pressure gauge Cooler Expansion tank N 2 gas Expansion tank Heater Heater Gear pump Gear pump Temp. : Max. 320 Press. : Max. 0.95MPa Dump tank Catch pan Ref) H. Ota et al., 2005 Ibaraki Meeting of the Japan Society of Mechanical Engineers, Hitachi-taga, Ibaraki, Japan, September 9,

11 Outer View of H 2 SO 4 Thermal-Hydraulic Test Loop Ref) H. Ota et al., 2005 Ibaraki Meeting of the Japan Society of Mechanical Engineers, Hitachi-taga, Ibaraki, Japan, September 9,

12 Concept of SO 3 Decomposer - counter flow type heat exchanger - H 2 SO 4 evaporates, and some amount of H 2 SO 4 vapor is decomposed into SO 3 gas and water vapor by high temperature heat supplied from the existing helium gas loop. He inlet SiC plates in one stage Thermal insulator Process gas outlet SiC plate type decomposer Process gas inlet Pressure vessel 1000 He outlet (unit: mm) Concept of the SiC plate type SO 3 decomposer for pilot test plant Process gas flow channel the internal volume charged with catalyst is about 25 liters, and then, the space velocity (SV) becomes about 5500 h -1. He gas flow channel (height: 2.5mm) Structure of the SO 3 decomposer unit (composed of 6 plate-type heat exchangers connected in series) Ref) A. Kanagawa et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

13 Thermal-Hydraulic Analytical Results - middle stage of the decomposer - 3rd stage maximum 597 o C minimum 0.28m/s maximum 0.50m/s SO 3 gas flow velocity distribution Inlet 625 o C Inlet 527 o C Temperature distribution in SO 3 flow path maximum 601 o C outlet 558 o C Temperature distribution in He flow path minimum 532 o C Temperature distribution in solid unit Ref) A. Kanagawa et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

14 Structure Analysis of SO 3 Decomposer Stress distributions (thermal stress + static stress) Contour in 1st stage maximum 53MPa Analytical results Leg Part Max 53 MPa Process-gas side Max 17 MPa (surface) Analytical results in all places were below the tensile stress of SiC. maximum 14MPa Contour in process gas channel Ref) A. Kanagawa et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

15 Mock-up Model of Plate-Type SO 3 Decomposer A SO 3 decomposer model consisting of 2 heat exchanger stages to confirm fabilicability and its mechanical strength. It was very difficult to connect two stages without cracks. It is necessary to improve a sintering connection technique between stages. 788mm 317mm 208 Process gas outlet 2 nd stage 1 st stage Process gas inlet Ref) A. Kanagawa et al., 13th Int. Conf. Nuclear Engineering (ICONE13), Beijing, China, May 16-20, 2005, ICONE

16 Flow Sheet of Catalyst Test Apparatus for SO 3 Decomposition Experimental conditions: Temp. : 753 Pressure : 0.31MPa Space velocity : 1000h -1 SO 3 decomposition ratio: 52.7 % ( 56.3% of equilibrium ratio) Condenser SO 2 Analyzer Pressure Control Valve P Charcoal filter Thermocouple O 2,Ar Test Section H TE H Water P Pressure gauge Electric heater H H 2 SO 4 Drain SO 2 Trap Catalyst Bed (Pt/SiO 2 ) H 2 SO 4 Evaporator H H 2 SO 4 Pump Ar H 2 SO 4 Tank Ref) A. Kanagawa et al., 2005 Ibaraki Meeting of the Japan Society of Mechanical Engineers, Hitachi-taga, Ibaraki, Japan, September 9,

17 Conclusion Concepts of the H 2 SO 4 and SO 3 decomposers made of SiC ceramics for the pilot test plant have proposed featuring corrosion resistant performance under high-temperature H 2 SO 4 and SO 3 operations. The feasibility of the proposed concepts has confirmed by thermal-hydraulic and mechanical strength analyses and test fabricated mock-up models. Future work Summary To accumulate design data for the pilot test plant, we will confirm the thermal-hydraulic performance of the H 2 SO 4 decomposer and the SO 3 decomposition performance in the packed catalyst layer by using the sulfuric acid flow test loop and the catalyst test apparatus. 17