Chemical Looping Gasification Sulfur By-Product

Transcription

1 Background: Coal Gasification Technology Chemical Looping Gasification Sulfur By-Product Fanxing Li and Liang-Shih Fan* Fly Ash By-Product Department of Chemical and Biomolecular Engineering The Ohio State University Slag By-Product Oct. 8th, 28 IGCC Efficiency: ~ 33% with control Steigel and Ramezan, 26 Chemical Looping Gasification Basic Concept Syngas Chemical Looping (SCL) Concept H 2 O C x H y O z 1. Reducer 3. Combustor Hot Spent Metal H 2 Fe 2 O 3 Fe 3 O 4 Reducer Oxidizer + H 2 O Metal Oxide H 2 O Sequestration 2. Oxidizer Fe C x H y MeO + Fuel Me + + H 2 O Me + H 2 O MeO + H 2 H 2 O H 2

2 Syngas Chemical Looping Process Particle Makeup Compressor Raw Candle Syngas Filter Hot Gas Cleanup Purge Hot Spent Gas Turbine Generator Fe 2 O 3 To Turbine Coal Fly Sulfur Ash Byproduct O 2 Hot Syngas Fe Reducer Combustor and Trace H 2 S, Hg H 2 (45 PSI) Oxygen Carrier Performance Oxidizer Compressor State-of-the-art N 2 Fe 3 O 4 Developed at OSU Recyclability of Commercial Fe 2 O 3 Recyclability of Composite Fe 2 O 3 Particles Reduction Oxidation Iron Based Composite particles are completely recyclable for more than 1 cycles

3 Pelletization Pellet Strength: Crushing Strength Test and Dropping Test (ASTM D4179) Frequency Fresh Pellet Pellet after Two Redox Cycles Commercial WGS Catalyst Pellet Crushing Strength (MPa) OSU Composite Pellets have significantly higher strength than commercial catalyst particles COST: ~ $6/ton (26 dollars) 2.5 kw th Bench Scale Moving Bed Motor SCL Process Demonstrations Light In Gas Out Light Out Temperature Measurement Gas / solid Sample Out Gas In Motor

4 Solid Conversion (%) Moving Bed Studies Reducer Operation Syngas Experiment (Reducer operation) Solid H2 CO Axil Position (inch) Nearly 1% conversion of syngas achieved Gas Conversions (%) Solid Conversion CH 4 Moving Bed Experiment (Liquid Fuel Synthesis test) Solid (meassured) Solid (Calculated) CH Distance from the bottom, inches Nearly 1% conversion of CH 4 achieved Syngas, Methane, and Other Hydrocarbons Can be Fully Converted to and H 2 O in SCL Reducer CH4 Conversion Nomalized H 2 Concentration (%) Moving Bed Studies Oxidizer Operation Time (min) Solid is fully regenerated to Fe 3 O 4, H 2 with an average purity of >99.95% is generated Fixed Bed Studies Demonstration of the Combustor Pellet Strength: Attrition Test.3 m 1 99 Fe 3 O 4 Oven Temperature 11 ºC Particle temperature ~12 ºC Furnace Furnace Spent Significant temperature increase observed, particle found to be still reactive after being exposed under proposed combustor operating conditions (> 12 ºC) Superficial Gas Velocity: v=18 m/s Valve Gas Inlet Gas Flow Meter 2.7 m.5 m Riser Downer 2. m ID: 1.96 cm OD: 2.5 cm Collector Pellets Distributor Percent of Unbroken Pellets Gas Outlet Filter Pellets > 2 mm Pellets >.71 mm Pellets >.71 mm with.57% fresh pellet makeup Number of Conveying Cycles Composite Particle Can Sustain 12 ºC.57% fresh pellet makeup is sufficient

5 ASPEN Simulation Common Assumptions A 1 MWt (HHV) GE/Texaco is considered Carbon regulation mandates > % carbon captured Simulation Studies The H 2 coming out of the system is compressed to 3 atm for transportation while the is compressed to 2 psi for geological sequestration No heat loss is assumed, heat can be integrated with a 1% efficiency The isentropic efficiencies is.83 for compressors,.86 for LP steam turbines,.88 for IP steam turbines, and.9 for gas turbines The energy consumption of PSA and sulfur removal units are provided by the low grade steam discharged from steam turbine Performance data obtained from bench scale unit is used for looping simulations Traditional Coal to Hydrogen Process Syngas Chemical Looping Process Assumption used is similar to those adopted by Mitretek Systems in their report to USDOE/NETL*. * Gray D. and Tomlinson G. Hydrogen from Coal. Mitretek Technical Paper. DOE contract No:DE- AM26-99FT4465. (22) Practical factors that are taken into account in the simulation: Pressure drop of the major chemical looping units, Energy consumption for particle transportation Energy loss due to the purging of the particles The simulation results represent a very conservative estimation of SCL performance based on current demonstration outcome

6 ASPEN Simulation Comparison Between SCL and Traditional Coal to Hydrogen/Electricity Process Coal feed (ton/hr) Carbon Captured (%) Conventional Max H Conventional Co-Production SCL Coal to Liquids Applications Hydrogen (ton/hr) Net Power (MW) Efficiency (%HHV) SCL process can increase the efficiency of State-of-theart coal to hydrogen process by 7 1% Syngas Chemical Looping in CTL Applications Process (ASPEN) Simulations Coal Pretreatment Mercury Raw Candl Removal Syngas e Filter Heat Hg Exchanger Sulfur BF Fly Byproduct W Ash Fresh Fe 2O 3 Pellets Spent Fe 2O 3 Powders Fe Reducer Fe 2O 3 H 2 High Pressure Pure H 2 Coal: 4,82 TPD Gasification/ 1 Cleaning/ Quench Cooling 8 Sulfur Polish LP steam 6 F-T Reactor 1 12 Depleted 2 H2O/CO Fuel 14 Reactor H 2/H 2O O 2 Cold Clean Syngas H 2/CO =.5 (Pneumatic Conveyor) Oxidizer Combust or Hot H2O/CO2 HRSG MP steam Dryer Compressed Product Separation 16 H2 Reactor 19 N 2 Warm Clean Syngas H 2/CO = 2:1 Wate r F-T Reactor C1-C4 and Generator Unconverted Syngas Product Separator II Separation Naphtha C5 C14 Diesel C17 and above Hydrocrack er Depleted Turbine Filter Water MW 2.4 MW Net MW 16.3 Plant Expander 15.5 MW Source: Noblis Systems Gases Upgrading 11 Gases Naptha 3,822 Diesel 8,186 Liquid Fuel: 12,8 BBPD 2.5 Bbl Fuel/Ton of Coal

7 Chemical Looping Process in a Coal-to-Liquids Configuration DOE/NETL-28/137 Sub-pilot Scale Demonstrations Independent Assessment of the Potential of the Chemical Looping in the Context of a Fischer-Tropsch Plant Conclusions: Overall, the Chemical Looping system proposed by OSU has the potential to significantly (~1%) increase the yield of the state-of-the-art Cobalt based F-T process and allow more efficient heat recovery and much lower (~19%) carbon emissions. Top Section Reducer Lower Middle Section Combustor Oxidizer Bottom Section

8 Coal-Direct Chemical Looping Process Other Chemical Looping Gasification Processes N 2 Ash/Spent Particle Coal Compressor Makeup Particle O 2 Fe 2 O 3 Reducer Fe/FeO Fe/FeO Fe Oxidizer Fe 3 O 4 Fe 2 O 3 +H 2 O H 2 Combustor Hot Spent Sulfur Byproduct Hg Removal H 2 S Remoal Expander H 2 Generator Reducer Configuration Calcium Looping Process Fe 2 O 3 + H 2 O 1 1 INTEGRATED WGS +H 2 S +COS + HCL CAPTURE Hydrogen Coal (and O 2 ) Particle reduction : CH 4 + Fe 2 O 3 + H 2 O + FeO Coal devolatilisation: Coal C + C x H y4 Char gasification and particle reduction: FeO + H 2 Fe + H 2 O FeO + CO Fe + + C 2CO Reaction Initiation: H 2 + FeO Fe + H 2 O H 2 O + C CO + H 2 + C 2CO 2CO + 2FeO x 2FeO x C 4CO 4CO + 4FeO x 4FeO x To Turbine Gasifier CaO CaCO 3 Oxygen H 2 +O 2 Rotary Calciner Fuel Cell Compressor Gas Turbine Generator HRSG Stack Fe Enhancer (H 2,, H 2 O) Slag Separation Fuels & Chemicals Turbine

9 Reaction Hydrogen Calcium Looping Process High Purity Hydrogen Production CaCO 3 Pure gas Regeneration CCR Process Use of metal oxide (CaO) in a reaction based capture/regeneration system Carbonation: CaO + CaCO 3 Hydrogen reactor Heat Output Syngas WGSR : CO + H 2O + H 2 removal : CaO + CO2 CaCO3 Sulfur : CaO + H2S CaS + H 2OO CaO+ COS CaS + Chloride : CaO + HCl CaCl 2 + H 2 O Heat Calciner Input Calcination: CaCO 3 CaO + Calcination: CaCO 3 CaO + Advantages of Carbonation/Calcination Reaction (CCR) Technology Operation under flue gas conditions High equilibrium capacities of sorbent Use of sorbent can achieve low equilibrium concentrations Regenerative cycle produces pure stream CaO CCR Process Demonstration Concluding Remarks

10 Comparison Among SCL, CDCL and Traditional Coal to Hydrogen/Electricity Processes Overall Process Efficiency SCL Gasfication-WGS IGCC-SELEXOL Subcritical MEA Ultra-supercritical MEA Ultra-Supercritical Chilled Ammonia Gasification H2 Membrane Syngas CLC CDCL % Electricity Ohio Coal Development Office (OCDO) of the Ohio Quality Development Authority (OAQDA) USDOE Acknowledgements Questions?