Experimental study of a fixed bed membrane reactor for hydrogen production

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1 Experimental study of a fixed bed membrane reactor for hydrogen production G.Di, G.Manzolini, S.Campanari, L.Roses Department of Energy Politecnico di Milano European Fuel Cell Piero Lunghi Conference 2013 Rome, December 12 th

Introduction 2 Energy saving and reduction of CO 2 emissions Growing electricity and heat demands in industrialized countries Consuption of large share of primary energy for residential & tertiary

2 Introduction 2 Energy saving and reduction of CO 2 emissions Growing electricity and heat demands in industrialized countries Consuption of large share of primary energy for residential & tertiary applications INNOVATIVE SOLUTIONS FOR SMALL SCALE POWER GENERATION AND CHP ARE REQUIRED LT PEM Fuel Cell based system Ø High electric efficiency Ø Low pollution emissions Ø High power density Ø Fast start and good efficiency at partial load -> daily start possible Ø Required high purity H 2 (CO concentration below ppm)

Possible solution: Membrane reactors 3 Fuel conversion and H 2 separation take place in a single reactor Thermodynamic and economic advantages foreseen for small scale heat and power generation

3 Possible solution: Membrane reactors 3 Fuel conversion and H 2 separation take place in a single reactor Thermodynamic and economic advantages foreseen for small scale heat and power generation system with PEMFC (0.1-3:5 kw el ) Ø Removing product from the reactor, significant enhancing conversion over theoretical equlibrium Ø Possibility to operate at high temperature and pressure (thermally and structurally stable) Ø High permselectivity for H 2

4 State of the art: Micro-CHP system layout with conventional TR 4 Ø 4 stages : SR, 2 WGS HT&LT, PROX Ø H2 diluted (CO 2 and other inerts) Ø FU FC < 1 Ø NG to heat SR

5 State of the art: Micro-CHP system layout with MR 5 Ø 1 stage : MR Ø Pure H2 (CO < 20 ppm) Ø Higher FU FC ( 1) Ø Use of H 2 O for sweep gas Ø H 2 O separation before FC Ø Retentate to heat Reformer

The Role of Palladium membranes 6 Membrane behavior Ø The driving force of the permeation mechanism is given by the difference in hydrogen partial

6 The Role of Palladium membranes 6 Membrane behavior Ø The driving force of the permeation mechanism is given by the difference in hydrogen partial pressure between the feed side and the side of extraction J [mol/m s Pa n ] Hydrogen Flux J H 2 = P * 0 Ea RT * t e p n F p n P J = H 2 f ( PH 2, T, tmem )

The Micro-Cogeneration Laboratory (LMC) Ø

This lab is located in the Milano Bovisa

7 The Micro-Cogeneration Laboratory (LMC) Ø Micro-cogen Lab (LMC), for testing CHP units (<300 kw thermal input, <100 kw electrical output) with variable gas fuel feeding (hydrogen, natural gas, syngas mixtures), fuel processors, electrolysers. This lab is located in the Milano Bovisa campus Ø It is operational since late Internal and external view of the lab building at Politecnico Bovisa site Gioele DiXXXXXXXXXXXXXX 7

Membrane Reactor Test Stand @ LMC 8 NG H 2 HX N 2

8 Membrane Reactor Test LMC 8 NG H 2 HX N 2 RET BPV VENT 150 cm DES SG MR H 2 GC H 2 O WP 230 cm

Membrane Reactor @ LMC 9 The Membrane Reactor Ø Fixed bed with 10 dead-end membrane tubes (200 cm 2 ) Ø Pd 0.77 -Ag 0.

9 Membrane LMC 9 The Membrane Reactor Ø Fixed bed with 10 dead-end membrane tubes (200 cm 2 ) Ø Pd Ag 0.23 layer on porous Inconel support Ø Max operating conditions: 700 C/10 bar Ø Max H 2 perm flow: 3 Nl/min Ø CPO catalyst Ni-Al 2 O 3 Ø No sweep gas

10 Membrane LMC 10 The Membrane Reactor Ø Membrane tubes 3.18 mm OD x 200 mm length Ø Tubes are welded by their open ends to a plate manifold Ø Reactor 1 OD Ø Temp is measured at 3 different heights and controlled by the furnaces power output

11 Experimental LMC 11 NG MFC Bronkhorst PT Dwyer TCs PI MFM CO 2 Bronkhorst H 2 O Or H 2 O/ EtOH Water Pump Grundfos Tracing Isopad RET PCV Air-loaded Tescom PI µgc Pollution MR + Furnace Reb H 2 MFM H 2 Bronkhorst

12 Permeation Tests 12 Membrane activation Ret. (Nl/min) H2 perm (Nl/min) P (barg) Tot. Flux (Nl/min) 0,4 4 0, K 3,5 3 0,25 2,5 0,2 2 0,15 1,5 0,1 1 0,05 0,

13 Permeation Tests 13 Hydrogen Permeation Test Ø K Ø kpa Ø H 2 pure, H 2 /N 2 or H 2 /H 2 O mix J H 2 = P * 0 Ea RT * t e p n F p n P Hydrogen flux proportional to ΔP H 2 flux measured (Nl/min) 3,5 3 2,5 2 1,5 673 K n = 1 H 2 flux resulting from Ea,P 0 (Nl/min) 3 2,5 2 1,5 1 0,5 0 H2/N2 mix Pure H2 R² = 0, ,5 1 1,5 2 2,5 3 H 2 flux measured (Nl/min) 0, Pressure on retentate side (kpa) For all tests Ø Ea = 7,72 kj/mol Ø P 0 = 3, mol/(m s Pa) Ø Higher hydrogen selectivity

14 Permeation Tests 14 H 2 measured Flux (Nl/min) Cost U.m. Value R [J/mol*K] n [adim] 1 yh2 perm [adim] 1 A mem [m2] 0.02 t mem [m] 4.50E-06 For H 2 /N 2 mix T furnace [K] TI 803 [K] y H2 ret y N2 ret P ret [barg]

15 Preliminary Reforming Tests 15 Ø First data from the membrane reactor test stand X CH 4 (%) 25% 20% 15% 10% 5% 0% 4 barg No Perm 5 barg No Perm 5 barg Perm 6 barg Perm Temperature ( C) Operating conditions Ø K Ø kpa Ø 1 Nl/min CH4 Ø S/C = 3 CH 4 conversion

16 Preliminary Reforming Tests 16 IN 0 Lower CH4 conversion values due to the temperature profile inside the reactor 100 T furnace T feed profile Ø1" Poor insulation of the bottom of the reactor cause a large temperature gradient Unexpected CH 4 production supported by reverse SR & WGS Reactor Length (mm) ΔT > 60 C 510 Membrane Tubes TC IN TC MID TC OUT /8" Ret Temperature (K) 800 1/4" H2

17 Preliminary Reforming Tests 17 Ø The agreement between experimental and numerical results Ø Mathematic one-dimensional model developed in Matlab Ø Kinetic model: Xu&Froment (SR & WGS)

18 Conclusions 18 Ø The measured membrane permeance is quite close to the values present in the literature Ø The parameters (Ea, P0 and n) of the general expressions for the hydrogen flux are not affected by the operating conditions Ø Preliminary reforming test issues are solved: first data from new ongoing experimental campaign are quite good Ø Future works will be dedicated on an experimental campaign to value the performance of the membrane reactor feeding bio-fuel Ø Integration of experimental results enable the optimization and calibration of the numerical modeling of the membrane reactor

Advanced m-chp systems

Advanced m-chp systems Advanced Multi-Fuel Reformer for Fuel CELL CHP Systems ( ReforCELL 278997) A Flexible natural gas membrane Reformer for m-chp applications (FERRET 621181) Advanced m-chp fuel CELL