Waste to Energy System Based on Solid Oxide Fuel Cells: Department - PowerPoint PPT Presentation

Waste to Energy System Based on Solid Oxide Fuel Cells: Department Store Case Marvin Mikael Rokni Thermal Energy Section, Technical University of Denmark (DTU) SSMW7 – 2019 Conference, Heraklion, Greece 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 1

Motivation  Municipal waste dispose is increasing significantly and must be taken care of.  Waste to Energy after basic recycling and producing fuel through waste gasification.  Multi generation systems is the most effective way from energetic/exergetic view.  Decentralized trigeneration plants for producing electricity, cooling and freshwater. Freshwater SOFC Waste Gasifier Absorption 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy

SOFC = Solid Oxide Fuel Cell Introduction Air Air & Steam Municipal Syngas Gasification SOFC Electric Plant Plant Power Waste Impurities Heat Ash Absorption Membrane Exhaust chiller Desalination gases Fresh Domestic water Cool 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy

GAP = Gasification Air Preheater SG = Steam Generator Gasifier Plant and its Modelling  Waste is dried and pyrolysis and then fed to the gasifier.  Drying is made by steam generator (SG) in a steam–loop.  Air is preheated in a gasifier preheater (GP) using the product gases from the gasifier.  Preheated air and some of the steam from the drying process is fed to the gasifier  Gasifier outlet temperature assumed 800 ° C, while inside temperature is around 1300 ° C.  Syngas is cleaned in a gas cleaner system (such as sulfur and chlorine). Gas Cleaning System Gasifier Steam Blower Flare Scrubber Gas Pump Cleaned Waste GAP SG gas Syngas Dryer Ash Air Impurities (Sulfur, chlorine, etc.) Steam loop 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy

Modeling Gasifier (cont.)  Equilibrium condition at outlet.  Mixture of perfect gases.  Minimizing the Gibbs energy at outlet, as described in Smith et al. (2005).  Introduction of a parameter to account for methane bypass without undergoing chemical reactions (about 1%). Parameter Value Waste temperature, (˚C) 15 inlet Drying inlet temperature, (˚C) 150 Gasifier temperature, (˚C) 800 Gasifier pressure drop, (bar) 0.005 Gasifier Gasifier carbon conversion factor 1 Gasifier non-equilibrium methane 0.01 Steam blower isentropic efficiency 0.8 outet Steam blower mechanical efficiency 0.98 Steam temperature in steam loop, (˚C) 150 ash Gas blower isentropic efficiency 0.7 Gas blower mechanical efficiency 0.95 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy

Modeling Gasifier (cont.) Parameter Waste Parameter Syngas C (vol %) 45.39 H 2 (vol %) 29.31 Ash (vol %) 20.26 N 2 (vol %) 32.39 S (vol %) 0.08 CO (vol %) 25.28 Cl (vol %) 0.08 CO 2 (vol %) 5.54 O (vol %) 26.56 H 2 O (vol %) 5.67 H (vol %) 6.21 CH 4 (vol %) 1.07 N (vol %) 1.42 Ar (vol %) 0.38 Moisture 18.12 HCl (ppmv) < 10 Cp (kJ/kg) 1.84 H 2 S (ppmv) < 1 HHV (kW), dry basis 19990 k        N  k w  0      G n g RT ln n p    i        G n A n A i i tot , out i , out m , in j ij mj i  1   j  1 i  1 m  1 k w       n A n A for j 1 ,N  i , in m , out ij mj    N G tot , out  i  1 m  1    A  0 for i  1 , k j ij   A ij ; element j (H, C, O, N) entering in  n  n j  1 i , out i , out i (H 2 , CH 4 , CO, CO 2 , H 2 O, O 2 , N 2 and Ar) N    A mj : element j of leaving compound 0  g  RT ln n p   A  0 for i  1 , k i , out i , out out j ij m (H 2 , CH 4 , CO, CO 2 , H 2 O, N 2 and Ar)  j 1 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy

Modelling of SOFC  For planar SOFCs developed by DTU – Risø and TOPSØE Fuel Cell (Denmark).  Zero-dimensional model allowing to be used for complex energy systems.  Calibrated against experimental in the range of 650 to 800 ° C  Keegan et al. (2002), Holtappels et al (1999), Kim and Virkar (1999), Peterson et al. (2005).        E E E E E FC Nernst act ohm conc   RT i  1  E  sinh d       act   4 0 . 001698 T 1 . 254 F 2 13 . 087 T 1 . 096 x10     t t t t = thickness, σ = conductivity    E  an  el  ca i   ohm d      an el ca         p i i i d = current density,           E B ln 1 H 2 d ln 1 d       conc p i i i as = anode limiting current       H 2 O as as 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 7

E x p e r im e n t M o d e l Design of SOFC Plant Fed by Syngas  Gas cleaner (Desulfurization)  Air compressor  Gas pump  Cathode preheating (CP)  Anode preheater (AP)  Burner 1 . 1 1  Anode side of SOFC 0 . 9  Burner 0 . 8 8 0 0  C 0 . 7 V o l t a g e 0 . 6 7 5 0  C 0 . 5 Gas 7 0 0  C 6 5 0  C 0 . 4 Off air Off fuel Cleaner 0 . 3 0 . 2 0 . 1 0 0 0 . 2 0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 1 . 8 2 2 A / c m SOFC Parameter Value Fuel utilization factor 0.7 Number of cells in stack 75 AP CP Number of stacks 160 Cathode pressure drop ratio, [bar] 0.04 Anode pressure drop ratio, [bar] 0.01 Burner 600 Cathode inlet temperature, [ ° C] 650 Air Anode inlet temperature, [ ° C] 780 Outlet temperatures [ ° C] DC/AC convertor efficiency 0.97 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 8

SHX = Solution Heat eXchanger Absorption Chiller  LiBr (Lithium Bromide) is used as Hot gas in Hot gas out absorbent. DESORBER 1 water LiBr Liquid out Pump Valve 4 DESORBER 2 solution Weak LiBr CONDENSER water Refrigerant (Water/Steam) SHX Valve 2 Valve 3 Valve 1 Pump Parameter Value ABSORBER EVAPORATOR 90 Desorber gas outlet temp. ( ° C) Rich solution (–) 0.6195 Liquid in Cooling (return) Cooling (supply) Week solution (–) 0.548 e.g. water 32 Condenser outlet temp. ( ° C) Cooling demand Pressure after valve 1 (bar) 0.008 Pressure after valve 3 (bar) 0.05 Absorber cooling inlet temp. (˚C) 20 Absorber cooling inlet pressure (bar) 16 Hot side outlet temp. for SHX (˚C) 70 Solution pump pressure high/low (bar) 0.8/0.05 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 9

SwP = Sea Water Preheater DCMD (Membrane Desalination)  LiBr (Lithium Bromide) is used as absorbent. DCMD Heat Pump Source SwP1 Sea Water Pump SwP2 Fresh water Parameter Value Fiber length 0.4 m Inner diameter of fiber 0.3 mm Membrane thickness 60 μm Porosity 75% Membrane conductivity 0.25 W/mK Shell diameter 0.003 m Number of fibers 3000 Packing density 60% Inlet temperature 80 ° C C k (individual contribution of Knudsen diffusion) 15.18 × 10 –4 [–] 5.1 × 103 m –1 C m (individual contribution of Molecular diffusion ) 12.97 × 10 –11 m C p (individual contribution of Poiseuille flow) 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 10

The Complete Plant Off fuel Off air Gasifier SOFC Waste Gas GAP SG Cleaner Dryer and AP CP Pyrolysis Ash Air Burner Air Steam loop Off Gases Desorber 1 Cooling liquid out DCM Off Gases Desorber 2 Pump D SwP1 Condenser Sea SHX Water SwP2 Fres Evaporator h Absorber water Cooling Dstrict Cooling liquid in 26 – 29 June 2019 DTU Mechanical Engineering Dr. M. M. Rokni SSWM7 – 2019 Heraklion Waste to Energy 11