Modeling-based Evaluation of Gasification Processes for High-Ash Coals

Transcription

1 Department of Energy Process Engineering and Chemical Engineering Modeling-based Evaluation of Gasification Processes for High-Ash Coals Martin Gräbner, Bernd Meyer 5 th International Freiberg Conference on IGCC & XtL Technologies May Leipzig, Germany (Paper 11-1) TU Bergakademie Freiberg I Institute of Energy Process Engineering and Chemical Engineering Reiche Zeche I Freiberg I Tel. +49(0)3731/ I Fax +49(0)3731/ evt@iec.tu-freiberg.de I Web

2 Outline 1. Trends in coal gasification development 2. Approach of this study 3. Results The influence of ash content Exergetic analysis 4. Conclusion 2

3 1 Trends in coal gasification development Available Gasification Technologies Shell Prenflo (Uhde) Siemens (GSP) Clean Coal Gasifier (Choren) HT-L Tsinghua 2-stageoxygen GE Energy (Texaco) Phillips 66 (E-Gas) Mitsubishi (MHI) MCSG (NRI) TPRI 2-stagecoal OMB (ECUST) Entrained-Flow Processes Sasol or Lurgi/AL dry ash BGL (Envirotherm) HTW (Uhde) U-Gas (GTI) TRIG (KBR) Fixed-Bed Processes Fluidized-Bed Processes Accroding to Gräbner, M. et al. Energy Strategy Reviews, 2012 (submitted). 3

4 1 Trends in coal gasification development New concepts for traditional technologies Shell partial water quench Prenflo full water quench [2] New concepts 11 INCI internal circulating gasifier [1] [14] Phillips 66 E-STR Entrained slagging transport reactor GE posimetric feeding system PWR compact gasifier [7] etc. [3] [4] Lurgi/AL Mark+ [5] Siemens radiant cooler [6] [1] de Graf, J. D.: Shell Coal Gasification Technology, Eindhoven Univ. of Tech., NL, [2] PRENFLO Broshure 2nd Edition, Uhde GmbH, Gelsenkirchen [3] Amick, P: ConocoPhillips Technology Solutions: Gasification Update, GTC Annual Conference, 2004 [4] Zuiker, J.R.: Building on History the Next Generation of Technology, GTC Annual Conference, 2009 [5] Weiss, M-M.: A new HP version of Lurgi s FBDB TM gasifier is bringing more value to clients, GTC Annual Conference, 2011 [6] Morehead, H.: Siemens IGCC and Gasification Update. GTC Annual Conference, [7] A. Darby. Status of the Pratt & Whitney Rocketdyne/DOE Advanced Single Stage Gasifier Development Program. GTC Annual Conference,

5 1 Trends in coal gasification development GE Siemens Overview on technology development drivers Lurgi FBDB Increase in single unit capacity Reduction of capital costs PWR Integration of dry feed solid pumps GE Increase in efficiency Inclusion of syngas cooler in portfolio Siemens HTW Increase in gasification pressure Inclusion of full water quench in portfolio Migration from slurry to dry feeding or slurry drying Increase in single-pass carbon conversion P66 Prenflo Shell Adaptation to lowgrade feedstock P66 GE INCI New concepts P66 5

6 2 Approach of this study Gasifiers Coal (Pitt#8/SAf) O 2 H 2 O O 2 Ternary Gasification Diagram Results of generic modeling H 2 O Coal Results of adiabatic equilibrium calculations (30 bar) Temparture & carbon conversion Cold gas efficiency & dry CH 4 yield Syngas yield & H 2 /CO ratio Selectivity of CO/C & CH 4 /C Location of gasifiers, maxima, operation domains and assessment of potential Gräbner, M.; Meyer, B.: Introduction of a ternary diagram for comprehensive evaluation of gasification processes for ash-rich coal, Fuel (in press),

7 2 Approach of this study Unified boundary conditions for gasifier modeling Coal (abbreviation) South Africa Pittsburgh #8 Coal rank (ASTM [8]) HV C Bit. HV A Bit. Moisture wt% Proximate analysis (dry basis) Ash wt% Volatiles wt% Fixed carbon wt% Ultimate analysis (dry & ash free basis) Carbon wt% Hydrogen wt% Oxygen wt% Nitrogen wt% Sulphur wt% Calorific Value (dry basis) Lower Heating Value MJ/kg Technology Verification data Shell Rich et al. [9] Siemens Babcock [10] GE McDaniel [11] Phillips 66 Woods et al. [12] HTW Bellin et al. [13] Exergy reference environment: T 0 = 25 C, p 0 = hpa Water is in the liquid state. Dry atmosphere: 78.1 vol% N 2, 21.0 vol% O 2 and 0.9 vol% Ar Chemical exergies of substances containing C, S and N are in inhibited equilibrium with the environment in their oxidized state (CO 2, SO 2, NO). [8] Miller, B.G. and Tillman, D.A. Combustion Engineering Issues for Solid Fuel Systems, Academic Press, [9] Rich, J.W. et al. WMPI - Waste Coal to Clean Liquid Fuels. Gasification Technologies Conference, [10] Deutsche Babcock. Kombikraftwerk mit GSP-Flugstromvergasung. Deutsche Babcock Werke AG Brochure, [11] McDaniel, J. Polk Power Station 250 MW IGCC. Compact Course Gasification, TU Bergakademie Freiberg, November [12] Woods, M.C. et al. Cost and Performance Baseline for Fossil Energy Plants, Volume 1, DOE/NETL-2007/1281, National Energy Technology Laboratory, [13] Bellin, A. et al. Kohlevergasung im Hochtemperatur-Winkler-Vergaser. Technical Report FK 03E1092C, Rheinbraun AG,

8 2 Approach of this study Unified boundary conditions for gasifier modeling Parameter Value Comment / Reference Pressure 30 bar Suitable for IGCC and several syntheses Temperature 1550/1450 C > 100 K above ash fluid temperature for slagging systems Thermal capacity 500 MW Coal input on LHV basis Coal/N 2 temperature 25 C N 2 : %vol purity, +3 bar above reactor Coal/transport gas 350 kg/m³(eff.) Higman and van der Burgt [14], Schingnitz [15] Solids in slurry 65 %wt Hornick and McDaniel [16] Slurry temperature 120 C Valenti [17] O 2 purity 95 %vol Residual: 3 %vol Ar, 2 %vol N 2 O 2 temperature 240 C +3 bar above reactor Moderator steam 37 bar / 246 C Saturated Quench water 37 bar / 175 C Preheating for high raw gas moisture IP steam 37 bar / 246 C No superheating HP steam 140 bar / 377 C von Morstein et al. [18] [14] Higman, C. and van der Burgt, M. Gasification. Elsevier Science, New York, [15] Schingnitz, M. G SP-Verfahren, In: Die Veredlung und Umwandlung von Kohle, Technologien und Projekte 1970 bis 2000 in Deutschland, DGMK, [16] Hornick, M.J. and McDaniel, J. TECO Polk Power Station IGCC Project - Final Report. Technical Report DE-FC-21-91Mc27363, Tampa Electric Company, Polk Power Station, [17] Valenti, M. Bringing coal into the 21st century. Mechanical Engineering, 117(2), [18] von Morstein, O. et al. Verbessertes IGCC-Kraftwerk ohne und mit CO2-Abtrennung, Endbericht COORIVA. Technischer Bericht AP2001, FK A,

9 3 Results: Understanding the influence of ash content Cold gas efficiency (CGE) Operation area, where CGE > 80%, becomes smaller and shifts below ash fluid temperature with increasing ash content Single-stage slagging gasifiers cannot be adapted! 9

10 3 Results: Understanding the influence of ash content Cold gas efficiency (CGE) Standard systems New concepts Slurry gasifiers are not suitable for high ash contents, dry-feed slagging system lose approx. 6 %-pts. in CGE Except for Siemens and Shell (only gas cooling is changed), all new concept show improvements Fluidized-bed processes are most independent from ash content INCI concept optimal for ash contents between 15 and 35 wt%(wf) 10

11 3 Results: Understanding the influence of ash content Syngas yield (SGY) Operation area where SGY > 2 m 3 /kg becomes smaller and shifts significantly below ash fluid temperature with increasing ash content Again single-stage slagging gasifiers cannot be adapted! 11

12 3 Results: Understanding the influence of ash content Syngas yield (SGY) High SGY up to 25 wt%(wf) ash for dry-fed entrained-flow gasifiers Significant improvements in the new concepts of GE and INCI E-STR concept improves with increasing ash content Traditional fluidized-bed processes (HTW) operate on a lower level INCI concept optimal for ash contents >40 wt%(wf) 12

13 3 Results: Exergetic analysis Exergy losses in gas cooling (in standard designs) Siemens: -37.7% thermomechanical (tm.) exergy loss due to full water quench Siemens GE-R P66 Shell P66: chemical qunech allows part of the tm. exergy to be converted to chemical exergy GE-R: in fouling-safe radiant cooler-only design 32.5% tm. exergy recovery by steam generation Shell: the cold gas quench causes an tm. exergy loss of -7.2% GE-RC: 51.6% of tm. exergy can be recovered employing radiant and convective syngas cooling (e.g. Polk IGCC) GE-RC 13

14 3 Results: Exergetic analysis Understanding the influence of ash content Syngas Yield (SGY) All new concept except the full water quench design from Shell lead to improved overall exergetic efficiency of the systems Improvements become more significant with increasing ash content of the coal INCI concept has the highest potential for high-ash coals 14

15 4 Conclusion Processing of high-ash coals (esp. fines): Development of high-conversion fluid-bed gasifiers is recommended INCI concept shows: Advantages in terms of cold gas efficiency at ash contents of wt%(wf) and syngas yield at >40 wt%(wf) The highest exergetic efficiency of all concepts highest potential for high-ash coals 15

16 End of Presentation Reiche Zeche Freiberg, Germany Detlev Müller Thank you for your attention Questions? Martin.Graebner@iec.tu-freiberg.de 16