Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances

Transcription

1 Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances S. Vakalis, D. Prando, F. Patuzzi and M. Baratieri Graz

2 Contents I. Introduction and general information II. The GAST project III. On-site measurements IV. Mass and energy balances V. Discussion of results VI. Conclusion Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 2

3 The concept of gasification Thermal process Sub-stoichiometric oxygen Packs energy into chemical bonds Mainly gaseous products Pyrolysis Gasification Combustion Increasing Oxygen Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 3

4 Small scale biomass gasification Small scale applications Downdraft Gasifier (ICE or GMT) Updraft Fluidized Bed Boilers Stirling ORC 200 kwe 1 MWe Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 4

5 Small scale gasification downdraft Evaporation of moisture Decomposition Combustible gases Gasification reactions Biomass Bio-oil Char Gases Combustion Products Producer gas (tar). Char / ash Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 5

6 The GAST project Funded by the Autonomous Province of South Tyrol Small scale biomass gasification plants Project partners Scope Monitoring and assessment Optimization of performance Environmental control Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 6

7 The GAST development (May-Dec 2013) New plants Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 7

8 The GAST stats Overall numbers 60 projects 21 authorized 14 operating Gasifier Fuel Size Type A tech. B tech. C tech. Monitoring campaign Wood Chips Wood Chips Pellets 45 kwe 120 kwth 135 kwe 230 kwth 180 kwe 270 kwth Joos Char Bed Rising CC Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 8

9 Process chain Gasification power plant (A tech.) P el : 45 kw el (nominal data) P th : 120 kw th WOOD CHIPS AIR GASIFIER (ER 0.3) DRY FILTER HEAT EXCHANGER ICE P el gas-tar sampling CHAR TAR gas-tar sampling Raccomandazione CTI 13 was followed (Italian committee of thermotechnical engineers) P th - syngas cooling Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 9 P th - water/oil cooling - exhausts cooling

10 Biomass characterization 45,580 % Wood Chips 41,023 % 5,795%,080% 7,011%,350% C H O N Ash Moisture LHV ~ 18 MJ / kg Ex ch ~ 20 MJ/ kg (lower heating value) (chemical exergy) Sampling UNI EN C, H, O UNI EN Humidity UNI EN Ash UNI EN Volatiles UNI EN HHV / LHV UNI EN Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 10

11 Gas composition Mobile micro- GC unit Columns: PLOT-U, MOLSIEVE Filtered gas composition N2 51,7% CH4 1,6% H2 17,1% CO 21,8% CO2 7,8% Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 11

12 Gas composition Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 12

13 Char analysis C, H, O UNI EN Humidity UNI EN LHV 23 MJ/kg (on dry basis) m CHAR /m BIOM 2 % Ash UNI EN HHV / LHV UNI EN Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 13

14 Tar sampling Micro GC UNI CEN TS Heated probe for sampling Sampling bottles (isopropanol 99%) Temperatures : + 40, -20 sampling bottles Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 14

15 Tar analysis Preliminar results on PAH compounds 10000,0 1000,0 100,0 10,0 1,0 0,1 Tar production (ng) GC-MS technique - separation DB5 MS column (J&W Scientific) - detection high resolution (R>10.000) mass spectrometer (GC-HRMS, MAT95XL, Thermo Scientific). - addition of deuterated internal standards. Uni Bz particolato ng/assoluti Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 15

16 Measuring mass A critical aspect of the balance of plant Measurement of mass [kg] and not volume [m 3] P m LHV fuel fuel fuel Bulk density of wood chips is not a constant parameter Volume of gas has significant variations due to fluctuating conditions (T, P) and fugacity Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 16

17 Mass balance Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 17

18 Measuring energy PT = Pe + Pth Electricity was measured directly from the meter Heat ΔTemp and V of water. Thermocouple (type T) Transit-time ultrasonic flow meter Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 18

19 Energy Fluxes Fluxes (kw) input 198 losses 57.2 heat 98 electricity ,75 energy demand of auxilaries (nominal data) Distribution losses 39 input 159 need of implementation of further measurements 198 kw (100%) kwe 22 % kwth 50 % Char 2% electricity 42.8 KW 4% 46% losses 29% Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 19

20 Exergy Fluxes Measure of the maximum amount of work that can theoretically be exchanged by a system in thermodynamic equilibrium with its surroundings through a ideal (reversible) process. [Ex = h - ho - To ( s so)] air 0.38 Input Exergy Flow (kw) losses Chem.exergy (char, tar) 221 Output gasifier Total exergy Physical exergy (heat) 20.8 Electricity 42.8 Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 20

21 Energy and Exergy Balances For an input of 40 kg per hour of wood chips (18 MJ /kg) electricity heat 42.8 kw 98 kw overall energy efficiency ~ 72 % net electric efficiency ~ 22% exergy efficiency (gasifier) ~ 63% Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 21

22 Conclusions Rapid development of small scale biomass gasifiers in South Tyrol incentives, CO 2 neutral, extensive biomass utilization in the area Gasifiers optimized for specific input parameters also: operating conditions, size Exergy is useful when the scope is production of work but cogeneration plants have also other product streams High T tar cracking but increased heat transfer and exergy losses Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 22

23 Outlook Complete the monitoring campaign apply the same procedure to the other plants (B, C) Compare different technologies on the basis of energy balance on the basis of exergy balance looking at the heat transfer performance Calibrate models b.o.p., with enhanced thermodynamic (multi stage, multi box ) Measuring the performance of biomass small scale gasification plants by implementing mass and energy balances 23

24 Thank you for the attention! Danke für Ihre Aufmerksamkeit! S. Vakalis, D. Prando, F. Patuzzi and M. Baratieri Graz