Low emission pulverised biomass fuel combustion systems

Transcription

1 ERA-NET Bioenergy Project FutureBioTec Technologies for clean biomass combustion 20 th September 2012, Graz, Austria Low emission pulverised biomass fuel combustion systems Pawel Bocian, Tomasz Golec

2 Presentation content methodology of pulverized fuel burners designing development of 5 15 kw burner development of 0,5 MW burner experimental investigations of the 5-15 kw and the 0,5 MW burners 20 MW burner up-scaling using CFD simulations possible implementations conclusions 2

3 IEn activities in development of biomass burners Development of biomass utilisation in power plants Beginning of research: first decade XXI Biomass combustion systems through coal burners Independent biomass feeding systems Aims: - Reducing of CO2 and NOx emission Limitations: - Exploitation problems, - Problems with bigger amounts of co-burned biomass above 10% of heat load The most promising. The main element of the system pulverised fuel burner 3

4 Methodology of pulverised fuel burners designing The principle laboratory investigations: Ignition time, combustion kinetics, fuel analysis, fineness, pneumatic transportation Burner concept Numerical optimisation Burner project During investigations several test stands were used During numerical simulations Fluent software and dedicated submodels were used Burner tests at the test stand (0.5 MW e.g.) Numerical optimisation of the burner at the test stand Burners production Implementation Burners simulation in a real combustion chamber of a boiler 4

5 Properties of the micronized straw the used fuel 5

6 Investigations of fuel ignition 1.5m drop tube furnace for investigation of pulverized fuel ignition and flame stabilization 6

7 Investigations of fuel ignition Polyfraction Reactor temperature, o C Primary air mass flow rate, Nm 3 /h

8 Investigations of fuel ignition 1.5m and 4m drop tubes for investigation of devolatilization and char burnout kinetics 8

9 Temperature profiles for T SA = 1273K Flame stand-off distance Q PA = 0.6 Nm 3 /h Q PA = 1 Nm 3 /h Q PA = 1.5 Nm 3 /h 9

10 5-15 kw test stand Combustion geometry chamber cylindrical shape length 680 mm diameter 135 mm burner mounted on the top 10

11 Development of a 5-15 kw burner Burner parameters swirl burner construction fuel F= kg/h primary air PA=1-2.7Nm 3 /h secondary air SA= m 3 n /h air excess rate λ total =

12 Second version of the burner (5~15 kw) Temperature, K Q pa = 2.7 Nm 3 /h Q sa = 3.0 Nm 3 /h Q sa = 8.7 Nm 3 /h Q sa = 14.4 Nm 3 /h 5 kw 10 kw 15 kw 18.4 g/min 36.9 g/min 55.3 g/min 12

13 10kW burner tests - results Influence of PA/SA ratio PA primary air injected with fuel SA secondary air injected around the primary air 13

14 10kW burner tests - results OFA air staging influence on emissions SA secondary air injected around the primary air OFA over fire air 14

15 Development of a 0,5 MW burner 15

16 Development of a 0,5 MW burner The burner view 16

17 Temperature, K 260kW burner modeling. Temperature profiles for different fuels Note: gravity vector Fuel Micornized Straw Fuel Tobacco Fuel Willow 17

18 0,5 MW burner tests The 0,5 MW test stand 18

19 0,5 MW burner tests The 0,5 MW test stand 19

20 0,5 MW burner - combustion chamber parameters during tests Initial value During experiments Primary air flow rate, Nm 3 /h Secondary air flow rate, Nm 3 /h Primary air temperature T p, C Secondary air temperature T s, C Wall temperature close to the burnert f, C Temperature at the outlet of the combustion chamber T out, C Biomass mass flow rate, kg/h

21 0,5 MW burner tests - results The burner stability ranges micronized straw tobacco willow The flame stability ranges were investigated by increasing and decreasing of the secondary air flow rate with the other constant parameters 21

22 0,5 MW burner tests - results OFA air staging influence on emissions of the tobacco waste combustion SA secondary air injected around the primary air OFA over fire air 22

23 0,5 MW burner tests results comparison for different fuels 23

24 20 MW burner development up-scaling Initial conditions for 15kW burner: Initial conditions for 20MW burner: A primary air = m 2 A secondary air = m 2 F primary air = kg/s F secondary air = kg/s F fuel = kg/s V primary air = 7.3 m/s V secondary air = 19.7 m/s T primary air = 293 K T secondary air = 293 K A primary air = m 2 A secondary air = m 2 F primary air = 1.88 kg/s F secondary air = 7 kg/s F fuel = 1.3 kg/s V primary air = 18 m/s V secondary air = 34 m/s T primary air = 293 K T secondary air = 293 K 24

25 20 MW burner development numerical modeling 25

26 20 MW burner development numerical modeling V, m/s Fluid Z velocity High velocity zone too high velocity of the secondary air outlet is not acceptable It is necessary to increase the cross-sectional area 26

27 20 MW burner development numerical modeling Vp, m/s Z Particle Z velocity Recirculation zone due to large burner face area this concept is not acceptable possible problems with slagging problems with overheating of the burner 27

28 20 MW burner implementation numerical modeling BP-1150 boiler 28

29 20 MW burner implementation numerical modeling temperature profiles comparison, o C agricultural biomass micronized straw 29

30 20 MW burner implementation numerical modeling agricultural biomass particle tracking micronized straw 30

31 Implementations Independent biomass fuel instalation at the OP-650 boiler 4 Part of the biomass installation at the tangential boiler OP-650: (1- burner, 2-pulverised fuel duct of the lower burner, 3- pulverised fuel duct of the higher burner, 4- fuel separator) 31

32 Implementations Burner installed at OR-32 boiler Two burners fired with wood dust from board production at fibre boards company FIBRIS SA in Przemyśl. The burners of changeable heat power in range from 1 to 3 MW were adopted for operation with coal fired stoker boiler OR- 32. Next two burners have been delivered for two similar OR-32 at another hardboard company - Koniecpolskie Zakłady Płyt Pilśniowych SA. Special 5 MW burners for agricultural biomass combustion were designed for the Dolna Odra power plant. The burners are a part of 20 MW biomass co-firing installation designed by IEn. 32

33 Implementations Burners installed at Ostrołęka power plant 3 boilers with 6 biomass burners each totally 18 burners 22MW each burner totally almost 400MW installed and fired with biomass 33

34 Conclusions small scale pulverised biomass burners (5-15kW) require very small particle sizes - micronization process guaranties that conditions small scale pulverised biomass burners require strong swirling combustion process, several single inclined secondary air nozzles around the primary air can ensure it burners with power load higher than 300kW must have different construction, with minimized frontal area to prevent overheating of the burner due to radiation and convection. Too strong recirculation can also cause unwanted slagging at the outlet of the burner the air staging can reduce NO emission by 50% pulverised fuel systems are very promising due to their dynamic properties, high efficiency and load flexibility 34

35 Thank you for your attention 35