Gasification of Biomass, Waste and Coal

Transcription

1 Institute for Energy Process Engineering and Chemical Engineering Gasification of Biomass, Waste and Coal Prof. Dr. Ing. Bernd Meyer Thermochemical Conversion for efficient Power and Fuel Supply Topsøe Catalysis Forum 2008 August 21 st 22 nd 2008, Havreholm Castle, Hornbæk, Denmark TU Bergakademie Freiberg I Institut für Energieverfahrenstechnik und Chemieingenieurwesen Reiche Zeche I Freiberg I Tel. 49(0)3731/ I Fax 49(0)3731/ evt@iec.tufreiberg.de I Web

2 Development of Biomass to Chemicals In competition with food! Main development Containing oil/fat Containing sugar/starch/cellulose Containing just C/H Rapeseed Coconuts Crops Potatoes Soya Wood chips Straw Pressing (physical conversion) Transesterification (chemical conversion) Alcoholic fermentation (biochemical conversion) Gasification (thermochemical conversion) Catalytical syntheses (chemical conversion) Vegetable oil Biodiesel Bioethanol MeOH, FTfuels, Biochemicals of 1 st generation 2 nd generation 2

3 Applications of Gasification and Catalytical Syntheses Currently desired pathways Biomass (Oil residues, Solid Steam/Water Air/O 2 wastes, Coal) Sulphur removal Ash Gasification Gas Conditioning Option for CO 2 capture H 2, CO, CO 2, CH 4, N 2 IGCC H 2 > 97% H 2 /N 2 = 3 H 2 /CO = 1 (H 2 CO 2 )/ (COCO 2 ) = 3 H 2 /CO = 0,52 Various Synthesis (H 2 CO 2 )/ (COCO 2 ) = 2 Fuel gas Hydrogen Ammonia Oxochemicals Methane (SNG) Methanol Hydrocarbons (FTfuels) 3

4 Problems of BiomassOnly Utilisation technological commercial problems (research needs) Absence of strong market pull Lack of infrastructure for controlled high quality feedstock supply Inability to gain performance guarantees Scaleup problems (maximum factor ~4) Long duration of demonstration (more than 10 years) Appropriate biomass feeding systems Hot gas cleanup (alternatives to Rectisol) Systems coping with wet feedstock (no pretreatment) Gasification product gas quality towards syntheses, no tars Ref.: Harry, A. M. et al.: IEA Bioenergy Publications Task 33 Workshop 1, EXCo 59, Golden, CO (2007); Babu, S. P.: Biomass & Bioenergy 29, 112 (2005) 4

5 Mix of Green and Black Biomass Green Biomass Max MW capacity Nonfossil CO 2 High volatiles (tar) Low LHV (high oxygen yield) Seasonal storage Inhomogeneous properties Low melting ash Up to 1,000 MW capacity Fossil CO 2 High carbon yield High LHV (low oxygen yield) Homogeneous properties Middle/high melting ash Possible high ash contents Black Biomass (Coal) Combined Gasification can provide: Reasonable economy of scale Reduction of fossil CO 2 emissions (optional CCS) Mitigation of harsh ash properties Creation of stable fuel mix experience of millions of operating hours of mature coal gasification systems 5

6 Possible Benefit of Latest Developments in Coal Gasification 6

7 Comparison of existing processes GE SFGT EGas Shell HTW Lurgi dry ash Biomass, highash coals (Slurry) (Slurry) / η CGE / Cconversion (69*/99) (79*/99) (84**/99) (81**/99) (74*/87) (73*/90 1 ) Low O 2, low T (Slurry) (high T) (Slurry) (high T) (low T) (very low T) Heat integration Load flexibility Simple design Gas quality (RSC 2, water quench) (refractory) (single step) (water quench) (membrane wall) (single step) (chem. quench) (refractory) (problematic two step design) (cold gas quench) no reinvention of the wheel, but combination of well known advantages of fixed bed fluidized bed entrained flow (membrane wall) (single step) (CSC 3 ) (refractory) (cyclone refractory) / (benzene) (counter current flow) (water jacket) (single step) (tars) * calculated value, ** literature value, 1) tar and oil excluded, 2) radiant syngas cooler, 3) convective syngas cooler 7

8 Two development lines (pilot plant studies) HTW gasifier (5/10 MW th ) INCI gasifier (5 MW th ) (High Temperature Winkler plus postgasification) (INternal CIrculation gasification) Biomass Coal Coal Biomass Sketch of pilot plant IEC entrainedflow gasification circulating fluidized bed gasification Sketch of pilot plant IEC fixbed gasification (postcombustion) Granular feedstock Complete conversion in min 25 bar 950 C Pulverized feedstock (high ash capable) Complete conversion in < 8 s 33 bar 1,000 C Gasifying agents O 2 /H 2 O/CO 2 Suitable for solid pump (Posimetric feeder) Dry ash (agglomeration, nearly carbonfree residue) 8

9 Introduction of HTW process HTW parameters: Gasifier Performance (pilot plant study) [1] : Wood Straw Lignite fuel (mass flow rate) kg/h 2,170 2,432 1,652 raw gas (volumetric flow rate) m 3 /h m 3 /h (STP) 3,726 3,753 3,662 raw gas (mass flow rate) kg/h 3,530 3,594 3,401 heat flow LHV (raw gas) MW th raw gas temperature (ex gasifier) C raw gas CH 4 vol% dry composition CO vol% dry CO 2 vol% dry H 2 vol% dry cold gas efficiency (LHV) ash (mass flow rate) H 2 S vol% dry N 2 vol% dry NH 3 ppm C x H y (mainly C 6 H 6 ) HTW Berrenrath/Wesseling, GER Operation pressure ~25 bar bar Operation temperature 900 1,000 C ~950 C Solids feeding (e.g. biomass pellets, chips) coal, biomass, peat Gasifying agents: oxygen, steam, CO 2 air/oxygen (1/5 less oxygen than entrained flow) Gas generation for syntheses (MeOH, FT, ) MeOH Total carbon conversion (> 98 %) > 87 % Postgasification of the bottoms none Dry ash removal dto. HCl ppm ppm % kg/h , , [1] Ref.: TU BA Freiberg, IEC:Final Report BtL, BMBF FK Appendices Gasifier Data 10 (2008) 9

10 Backup Turnkey design of HTW pilot scale plant Location: Freiberg, Reiche Zeche 10

11 Backup Turnkey design of INCI pilot scale plant Location: Freiberg, Reiche Zeche 11

12 Introduction of INCIprocess dustloaded productgas cooling water INCIPrinciple: Internal Circulation Gasifier (Mild transport gasifier) Multifuel, highash, lowrank, biomass Low investment costs ( 50 % in comparison to Siemens partial quench or Shell) coal gasification agent tuyres primary gasification agent Low operation costs (20 % O 2 consumption in comparison to Siemens partial quench or Shell) Highest overall IGCC efficiency (increase of 35 % points net efficiency) Possibility to equip with the solid feed pump patents cooling water secondary gasification agent ash 12

13 Introduction of INCIprocess Lessons learnt: cooling water Water jacket, studded/ramming mass (SiC), no brick lining fluidised bed gasifiers (HTW) [1] Slagfree tuyere nozzles Internal circulation (INCI transportprinciple, CFB) Δp coal gasification agent tuyres primary gasification agent Ash particle agglomeration Process control by differential pressure Fouling free HRSG operation due to high dust carbon content (approx. 50 %wt) limited temperature (~1,000 C) at raw gas outlet, lower oxygen consumption, no tars entrained flow gasifiers (SCGP, others) High flame temperatures > 2,000 C ensures partial ash melting, independent of ash properties conditions of entrained flow in front of each nozzle and in resulting central flame cooling water Ref.: [1] Gräbner, Ogiseck, Meyer: Fuel Proc. Tech. 88 (2007) ; [2] Scala, Chirone: Energy & Fuels 20 (2006)

14 Introduction of INCIprocess Δp coal cooling water gasification agent tuyres primary gasification agent new principle of postgasification (similar to Lurgi dry ash fixed bed) Complete carbon and minerals oxidation by introduction of O 2 /CO 2 or O 2 /H 2 Omixtures (5..13 %vol O 2 ), total carbon conversion Complete sensible and fusion heat recovery into gasification process cooling water 14

15 Introduction of INCIprocess Resulting advantages: 1 Outlet temperature ~ 1,000 C minus 20 % O 2 demand, no hot gas cyclone necessary lower CAPEX 2 Inherent safety due to C hold up > 20 sec. lower CAPEX, robust operation 3 Cooling jacket (from Lurgi fixed bed principle, no refractory lining) start up < 5 hours 4 Complete ash agglomeration (granular slag) ash melting at > 2,000 C, independent of coal and ash properties high ash low reactive coals 5 Solid pump usable no lock hopper systems lower CAPEX, lower OPEX 6 Only one oxygen supply level, noncooled tuyeres lower CAPEX, robust operation 7 Integrated bottom ash cooling < C No external ash cooling devices lower CAPEX, lower OPEX 15

16 Comparison of selected performance parameters Gasifier performance comparison for hard coal 25 %wt ash (calculated) pressure temperature carbon conversion oxygen demand steam demand Gas analysis (dry) Residual LHV (dry gas) LHV (coal) Cold gas efficiency bar C % kg/kg (daf) kg/kg (daf) %vol MJ/m³ (STP) MJ/kg % GEtype * SFGTtype * HTWtype * MHItype * INCI process 0.39 CO %vol H 2 %vol CH 4 %vol H 2 S %vol CO 2 %vol N 2 %vol C x H y %vol * Gasifiers named as type are thermodynamically modelled as a type of the system and may not show exact accordance to technical realized facilities. 16

17 Development priorities [1] Our international contacts exhibit strong indication of common priorities: 1 st world wide priorities: Large scale gasification of ashrich and lowrank coals, optionally combined with biomass no largescale biomass utilization High pressure polygeneration gasifiers (with CCS?) Highest cold gas efficiencies (low temperature or mild gasification) Solid feed systems (dry and free of gas) Small scale distributed generation (substitution of natural gas) 2 nd world wide priorities: Trace element behaviour (new topic: Selenium) Processintegrated heat recovery Dynamics: abandonment of redundancies Flexible load concepts for IGCC Coal stimulates developments for Biomass 1 Ref: Meyer: COORETEC Advisory Board Meeting German Ministry of Economics, Berlin (2008) 17

18 General Conclusions and IEC Research Focuses General Conclusions: 1 st Thesis: Priority of development of 3 rd generation coal gasifiers 2 nd Thesis: No special gasifiers for biomass, but adaption or combination with coal systems 3 rd Thesis: Combined coal and biomass gasification systems including Carbon Capture and Sequestration IEC Research Related to Biomass Gasification: 1 st Focus: Cycles of mineral matters and trace materials (experimental investigations, thermodynamic modelling of chemical and phase equilibria) 2 nd Focus: Concepts studies on biomass to liquid routes (flow sheet simulations, theoretical investigations) 3 rd Focus: Development of 3 rd generation gasification processes (flow sheet simulations, experimental investigations, CFDsimulations) 18

19 Save the Date! 1821 May

20 End of Presentation Thank you for your attention, questions are welcome Contact information: Prof. Dr.Ing. Bernd Meyer 20