Dynamische Simulation von Reaktoren zur Festbettmethanisierung

Transcription

1 Deutsches BiomasseForschungsZentrum gemeinnützige GmbH Workshop Fließschemasimulationen in der Energietechnik 2012 Dynamische Simulation von Reaktoren zur Festbettmethanisierung Stefan Rönsch, Steffi Matthischke, Markus Müller, Philipp Eichler Leipzig, 13. November 2012 Deutsches BiomasseForschungsZentrum gemeinnützige GmbH, Torgauer Str. 116, D Leipzig,

2 1 Background Need for flexible power provision plants Electricity price in /MWh The electricity price is an average price per hour at the EEX spotmarket. 0:30 2:30 4:30 6:30 8:30 10:30 12:30 14:30 16:30 18:30 20:30 22:30 Time at October the 17 th

3 2 Object of investigation Biomasse Biomassebereitstellung Ernte, Sammlung Konditionierung, Transport, Lagerung Syngas methanation as an option for flexible power provison with gasification plants. Biomassevergasung Gasreinigung Methanisierung Roh-SNG-Aufbereitung Biomassekonversion SNG Sekundärenergieträger 3

4 2 Object of investigation Challenge: Methanation reactors have to operated with flexible load! Question 1: Where are the constraints of an operation with flexible load? Question 2: How can an operation with flexible load be ensured? 4

5 2 Object of investigation ADAM1 (TREMP) as a possible fixed-bed methanation concept: Syngas Reactor 1 Reactor 2 Reactor 3 Steam superheater Water preheater Gas cooler (Recycle) Steam generator Steam generator SNG Gas compressor (Recycle) Heat exchanger Heat exchanger Condensate 5

6 3 Methods Reactor Modelling: Discretisation Syngas i=1 i=2 Reactor 1 Discretisation i=3... Catalyst Wall Raw SNG 6

7 3 Methods Reactor modelling: Conservation equations Component balances: 0 Energy balances:, Storage Convection Source/Sink reaction Source/Sink heat, 0,, 0, 0 Momentum balance (Ergun equation): f 0 DA-System with approx. 1 Mio. equations. 7

8 3 Methods Reactor modelling: Rates of reaction Reactions: CO-Methanation: 3 H 2 + CO CH 4 + H 2 O CO 2 -Methanation: 4 H 2 + CO 2 CH H 2 O Watergas-Shift: CO 2 + H 2 CO + H 2 O Hougen-Watson-mechanism:. 1 Calculation of rate coefficients and adsorption coefficients based on [Xu 1989]: Ni/MgAl 2 O 4 catalyst. [Xu 1989]: Methane Steam Reforming, Methantion and Water-Gas Shift: I. Intrinsic Kinetics, AIChE Journal, Vol. 35 (1989),

9 4 Validation Object of investigation Syngas Reactor 1 Reactor 2 Reactor 3 Steam superheater Water preheater Gas cooler (Recycle) Steam generator Steam generator SNG Gas compressor (Recycle) Heat exchanger Heat exchanger Condensate 9

10 4 Validation Gas temperature at outlet of reactor 1 Syngas Reactor 1 T = 300 C p = 27 bar ADAM1: Steam superheater T = 581 C p = 27 bar Recycle rate: R = 2.65 Gas cooler (Recycle) Steam generator Simulation: T = 545 C P = 27 bar Heat exchanger Gas compressor (Recycle) 10

11 4 Validation Gas temperature at outlet of reactor 2 and 3 T = 269 C ADAM1: T = 303 C p = 27 bar ADAM1: T = 445 C p = 27 bar Simulation: T = 300 C P = 27 bar Simulation: T = 420 C P = 27 bar T = 268 C 11

12 4 Validation Gas temperature in reactor 1 Measurements at ADAM1 of [Höhlein 1980] (adapted): 750 Simulation with reaction rates of [Xu 1989]: 750 Simulation with reaction rates of [Kopyscinski 2010]: 750 Gas temperature in C MCR-2X Catalyst (Haldor Topsoe) Gas temperature in C Ni/MgAl 2 O 4 catalyst Gas temperature in C Ni/γ-Al 2 O 3 catalyst Reactor length in mm Reactor length in mm Reactor length in mm [Höhlein 1980]: Methanisierung kohlenmonoxidreicher Gase beim Energie-Transport, CIT, Vol. 52 (1980), [Kopyscinski 2010]: Production of synthetic natural gas in a fluidized bed reactor, Dissertation, ETH Zurich, 2010 [Xu 1989]: Methane Steam Reforming, Methantion and Water-Gas Shift: I. Intrinsic Kinetics, AIChE Journal, Vol. 35 (1989),

13 4 Validation Test facility for kinetic studies Operational data: Type: Fixed-bed reactor Catalyst: Südchemie Meth 134 Pressure: up to 5 bar Temperature: up to 450 C Gas throughput: up to 0.75 m³/h (i.n.) 13

14 5 Results Gas temperature in reactor 1 after gas flow increase 14

15 5 Results Temperatures in reactor 1 after gas flow increase Gas temperature Temperature limitations of fixed-bed methanation: Temperature in C Catalyst temperature Wall temperature < 300 C: carbonyl formation 4 CO + Ni Ni(CO) 4 > 550 C: catalyst sintering (depending on catalyst) Time in s > 600 C: soot formation (depending on catalyst and steam content) 15

16 6 Outlook Test facility for reactor control optimisation Operational data: Type: Fixed-bed reactor Catalyst: Südchemie Meth 134 Pressure: up to 60 bar Temperature: up to 850 C Gas throughput: up to 0.75 m³/h (i.n.) 16

17 7 Conclusions Future methanation concepts have to be flexible in operation. Operation over nominal load may lead to catalyst sintering. Adapted reactor cooling and cooling control is required. Picture source: Haldor Topsoe, worldpress, Briegert 17

18 Thank you 18