Development of a Chemical Looping Gasification Process

Transcription

1 Development of a Chemical Looping Gasification Process Bo Feng School of Mechanical and Mining Engineering, The University of Queensland, St Lucia, Qld 4072, Australia.

2 Outline Motivation Zero emission power generation The problems loss-in-capacity of calciumbased sorbents and ash melting The solution how we tried to solve the problem The results fabrication of calcium-based sorbents without the problem Summary Ongoing and future work

3 Motivation: Zero emission power generation Plant efficiency > 50% ~100 % CO 2 capture CO 2 adsorbing material CAM+CO 2 ->CAM-CO 2 CAM-CO 2 ->CAM+CO 2 Simultaneous high efficiency and CO 2 capture is possible, e.g. in HyPr-RING, GE-UFP, ZECA etc. Combining gasification, water gas shift reaction and CO 2 separation into a single reactor. Chemical Looping Gasification

4 Motivation: Zero emission power generation Plant efficiency > 50% ~100 % CO 2 capture CO 2 adsorbing material CAM+CO 2 ->CAM-CO 2 CAM-CO 2 ->CAM+CO 2 CO 2 adsorbing material plays an important role. Fluidized bed gasifier would be the most suitable (T,P, coal type). Oxy-fuel combustion of residue carbon or coal for CAM regeneration. Gas cleanup and GT/Fuel cell could be the same as an IGCC.

5 Motivation: Zero emission power generation CO 2 adsorbing material CAM+CO 2 ->CAM-CO 2 CAM-CO 2 ->CAM+CO 2 Proof-of-concept work (JCOAL): high purity of hydrogen can be produced with addition of CaO in a pressurized FB gasifier Two major problems: raw CaO loses capacity after cycles; ash melting due to the addition of raw CaO

6 Motivation: zero emission power generation Any CAM better than raw CaO? CaO appears to be the best candidate so far as CO 2 sorbent thermodynamically to be used in a coal gasifier, among various metal oxides, microporous or mesoporous materials, hydrotalcite like compounds, lithium based materials etc Carbonation: CO 2 + CaO CaCO 3 Calcination: CaCO 3 CaO + CO 2 Feng B, An H, Tan E. Energy & Fuels (2007), 21(2), School of Mechanical and Mining Engineering However raw CaO has a problem

7 Problem1: Loss-in-capacity of CaO after cycles Conversion Loss in capacity Number of cycles Barker Silaban Aihara Shimizu Curran School of Mechanical and Mining Engineering How to solve the problem?

8 Problem2: Ash melting due to CaO Shiying Lin, Michiaki Harada, Yoshizo Suzuki, Hiroyuki Hatano, Fuel 85, 2006, How to solve the problems?

9 Objectives of the project Objective 1: to solve the current problems. Objective 2: to demonstrate in lab scale the efficiency of a continuous pressurized chemical looping gasification system. Objective 3: to evaluate the feasibility of pilot scale demonstration.

10 Reaction between CaO particle and CO 2 Macropore volume Grain (~ 400 nm) crystals (5 100 nm) CaO CO 2 CaCO 3

11 Main cause of loss-in-capacity: CaCO 3 crystal sintering CaCO3 CaCO3 During regeneration (calcination)!

12 Main cause of ash melting: CaCO 3 reduces melting point CaCO3 Ash particles

13 Hypothesis: how to overcome Problem1 1. Use separated particles CaCO3 CaCO3

14 Hypothesis: how to overcome problem1 CaCO 3 product layer, resist CO 2 CO 2 2. Use small particles (nano-size) Proposed solution to Problem1: Uniform distribution of nano-cao on inert porous matrix

15 Hypothesis: how to overcome problem2 CaCO3 Ash particles Inert porous outer layer

16 Hypothesis: proposed solution Inert framework How to achieve it? CaCO3 Ash particles Inert outer layer Nano-sized CaO

17 Tested Synthesis Methods Loading CaO on supports: Physical Mixing (problem persists) Wet impregnation (require soluble CaO precursors, high loading difficult) Co-precipitation (problem persists) Sol-gel process (problem persists) Wet-mixing process (problem solved?!) What CaO precursor to use? How to control loading amount?

18 Sorbents by Wet-mixing Method Carbonation: 650 C, 30 min, in 15% CO2 Calcination: 900 C, 10 min, in N2

19 Sorbents by Wet-Mixing Method Capture capacity (g/g) M:CLAL50 50% CaO Time (minute)

20 Sorbents by Wet-Mixing Method Capture capacity, c(g/g) theoretical max. capacity 90% CaO wt.% Now, does it require 300 steps to fabricate the sorbent? What is the maximum CaO fraction? Is it easy to regenerate the sorbent?

21 The Method Easy steps! Any loading is possible. Precursors? Liu, W., Feng, B., Diniz da Costa, J.C. And Wang, G.X. (2010), Environmental Science and Technology, 44(8), , 2010 School of Mechanical and Mining Engineering

22 Sample Calcination atmosph ere Calcination Time (h) Calcination Temperature ( C) CaO wt.% Support matrix CGMG52 Air, furnace MgO CGMG67 Air, furnace MgO CGMG75 Air, furnace MgO CGMG85 Air, furnace MgO CGMG95 Air, furnace MgO CLAL50 Air, furnace Ca 9 Al 6 O 18 CFMA10 Air, furnace MgO CAMA30 N 2, TGA MgO CAMA55 N 2, TGA MgO CAMA65 N 2, TGA MgO CAMA70 N 2, TGA MgO CLML55 N 2, TGA MgO CLML65 N 2, TGA MgO CLML70 N 2, TGA MgO CAML55 N 2, TGA MgO CAML65 N 2, TGA MgO CAML70 N 2, TGA MgO CLMA55 N 2, TGA MgO CACLMAML50 N 2, TGA MgO CG: calcium D- gluconate monohydrate CA: calcium acetate hydrate CL: calcium L- lactate hydrate CF: calcium formate MA: magnesium acetate tetrahydrate ML: magnesium L-lactate hydrate MG: magnesium D-gluconate hydrate AL: Aluminum L- lactate

23 Sorbents from Various Precursors

24 Sorbents from Various Precursors Observations: 1. All sorbents performed very well; 2. The performance was insensitive to precursor type; What is the highest CaO fraction?

25 Capacity vs CaO content ~82 wt% CaO 3D percolation theory!

26 Regeneration of New Sorbents Better carbonation! Easier regeneration!

27 Performance under severer condition Capture capacity (g/g) % CaO Carbonation: 880 C, 2 h, in 100% CO 2 Calcination: 900 C, 10 min, in N 2 Time (minute) Why did it work???

28 TEM Images of Sorbent Nano-sized CaO particles (100 nm) are separated uniformly by nano-sized inert material particles (20 nm) Why possible by this method? Perfect mixing of precursors! better mixing than any other methods tested

29 Sorbent composition 3000 A:calcined in air 2500 A:CaO B:MgO C:Ca 9 Al 6 O 18 B Intensity B A A B B A B A A A A CFMA10 A A A B B B A A BA A CGMG75 A C A A C C A C A C A A CLAL Theta

30 Summary Objective 1 partially achieved: A new method was discovered for the fabrication of CaO-based sorbents without the problem of loss-in-capacity. Objectives 2 and 3 are still to be achieved.

31 Product design and formulation Gas reactor Gas-solid reactor Optimize the formulae Naked Particle Calcium Support Binder Best performance cheapest Core-in-shell Calcium Support Binder Shell material Shell Binder

32 Product mass production Spray-drying Coating Both are commercially proven! Granulation

33 Testing of Products CO2 Ash High T High P Multiple Cycles Regenerator H2 Best performance product Cheapest product Natural dolomite To be tested O2 H2O Gasifier Coal Coal gasification with CCM (JCoal reactor, batch reactor, under high T and high P, Zhejiang Univ, high pressure continuous) Performance over cycles (Southeast U reactor, continuous reactor, under normal P and high T)

34 Current Progress and Plan Before 2009 Identification of candidates Product design and formulation Screening of candidates Solving problems of candidates From 2011 Product mass production Testing of products under realistic gasification conditions Application of materials Naked particle Core-in-shell particle Cheapest product Best performance product completed on-going planned

35 Acknowledgement Research collaborators: Dr. Geoff Wang, Prof. Joe da Costa, Dr. Matthew Cleary, Prof. Qinhui Wang, Prof.Laihong Shen, Dr. Peter Ashman, Prof. John Barry, Dr. Shiying Lin (JCOAL), Dr. Takashi Kiga (JCOAL) PhDs: Mr. Wenqiang Liu, Ms. Mingnv Guo, Mr. Junjun Yin, Mr. Hui An Australian Research Council UniQuest The University of Queensland ECR fund Infrastructure fund

36 Thank you! Advice / Collaboration / Investment Appreciated!