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FLUIDIZED BED COMBUSTION TESTING,CHARACTERIZATION
AND RESEARCH SERVICES
Fluidised Bed Combustion research in VTT aims at promoting technological development ofheating and power plants in order to secure high level of plant availability and reliability. Inmultifuel applications our research activities focus on solving problems related to ashbehaviour such as fouling of heat transfer surfaces and hot corrosion. As the legislation onemission levels of heating and power plants is continuously tightening, we can offer ourclients expertise on emission control and reduction techniques. In process development areawe promote the development of high efficiency CFB processes. Our aim is to develop processmeasurement and modelling methods in order to deepen knowledge on CFB process in all itscomplexity. Majority of the activities is experimental research work, which takes advantage ofour unique test facilities, strong experience and contacts covering the whole researchcommunity of Europe.
We conform to the Quality Management System Standard ISO 9001:2000.
FLUIDIZED BED COMBUSTION TESTING,CHARACTERIZATION
AND RESEARCH SERVICES
Tools and facilities
2D & 3D
Bench scale reactors(cold and hot)
Pilot scale reactors50 kW, 20 kW
Commercial CFBboilers
0D
Experimental facilities, scale up
1D
Modeling tools, modeling of processes in multiple scales
VTT have a pilot CFB reactor, a pilot BFB reactor, a bench scale BFB reactor and afluidized bed erosion tester. Depending on the objectives and requirements thesedevices can be applied for the combustion and material testing.
Pilot Scale test rig &Bench Scale test rig
Full Scale units
Stationary andDynamic models
Population balanceCombustion
EmissionsSteam cycle Controlsystem
Boiler simulatorInformation gained data
•3Dmodels, 1Dmodels
Secondarycyclone
Fuel container 1 and 2Zone 1
Zone 2
Gas coolig
Primarycyclone
Observation port Sampling port/Deposit probe
Zone 3
Zone 4To stack
Sampling port
Sampling port
Observation and Sampling port/Deposit probe
Additivecontainer
Air
Secondary air(preheated)
Primary gas heating
Nitrogen
PC control and data logging system
Sampling port
Sampling port
Bag filter
CFB and BFB reactors are equipped with several separately controlledelectrically heated and water/aircooled zones in order to control the processconditions (for example oxygen level, temperature and load) almostindependently. There are several ports in the freeboard area for gas and solidmaterial sampling. Typically the aim is to carry out a pilot size test burn tocharacterize the fuel in terms of the combustion properties for a CFB or a BFBpower plant. Combustion conditions can be adjusted to correspond with thoseprevailing in fullscale boilers. The test rigs are applied in research workrelating to the formation of pollutants, ash property characterisation andcombustion behaviour characterisations of problematic fuels. Depositformation can be studied by inserting aircooled probes into the reactors'furnace and flue gas paths. It is also excellent environment for characterisingfine fly ash emissions in multifuel and waste combustion. Development ofcombustion process includes analysis of experimental results applying steadystate and dynamic process models and also testing of advanced process controlmethods can be carried out.
Comparison of methods to control flue gasoxygen concentration.
Measured SO2 emissions
Fuel 1
Fuel 2
0 %
20 %
40 %
60 %
80 %
100 %
120 %
0 1 2 3 4 5Ca/Sratio
Calculated SO2 for 100% conversion
Measured SO2 concentration in flue gas asa function of Ca/Stratio.
FB REACTORS
TEST FACILITIES
ash properties, ash split (bottomash vs.fly ash)
Typical issues studied with pilot CFB and BFB reactors:
fuel and limestone reactivity
advanced combustion control
bed agglomerationcombustion profiles (gas, solidmaterial, temperature, heat transfer)
limestone dosage
emissions
deposit formation
Comparison of controllers
0
20
40
60
80
100
120
140
0 50 100 150 200 250 300 350Time (s)
Set point
PID
Smith
GPC
flue gas
1
n n+1
to stack
2
n1
3
n2
Primary air
To stack
Samplingport
Samplingport
Samplingport
Gas cooling
Bagfi lter
Gas probe
Observationport
Cyclone
Gassample
Temperaturecontrol
Tertiary air optional
Tertiary air optional
Tertiary air (preheated)
Fuel container 2Fuel container 1
Secondary air(preheated)
Nitrogen
Air
Additivecontainer
Primary gas heating
Heating zone 2/Cooling zone 2
Heating zone 3
Heating zone 4
Heating zone 1/Cooling zone 1
BEDmade of quarz
PC control and data logging system
Obervation port
Obervation port
Obervation port
Obervation port/Deposit probe
Depositprobe
Cocombustion of biomass and REF: distribution ofchlorine between HCl and particulate matter (alkalichlorides) in 870°C BFB furnace.
Preheated primary air is fed to the furnace through the grid. Oxygen concentration in the furnace is set to desired level with nitrogen.Alsodifferent kind of gas mixtures can be used e.g. O , CO , SO , CO, NO in addition to air and nitrogen. Temperature and pressure profilesalong the riser are measured. Temperature is controlled inside the reactor tube with surrounding electric heaters.
2 2 2
Air
Nitrogen
Secondary air
Continuousfuel feed
Fuel batch feed
Cooler/heater
Cooler
Primary gas heatingPC control anddata logging system
Cyclone
FilterTo Stack
Air
Nitrogen
Secondary air
Continuousfuel feed
Fuel batch feed
Cooler/heater
Cooler
Primary gas heatingPC control anddata logging system
Cyclone
FilterTo Stack
Characterization offuels and sorbents
Comminution
bed agglomeration
NOx formation
Typical issues studied with bench scale reactor:
Agglomeration of bed material
Subprocess foremission formation
Reactivity
5
10
15
20
25
0 50 100 150 200
Brown coal (A)
Bituminous coal (B)
Anthracite (C)
A
B
C
Reactivity test Fuel batch experiments
250
BENCH SCALE CFB/BFB REACTOR
0
2
4
6
8
10
12
14
0,01 0,1 1 10 100 1000 10000Particle size (
Time[s]
m)
Calcination
Sulfur capture
Changes in PSDduring sulfur capture
Typical operational parameters for CFB and BFB pilots
Dimensions of furnace: CFB BFBHight (m) 8 4
Diameter (m) 0.17 0.23
Feeds:Fuel (g/s) 1.56 0.91.3
Fuel power (kW) 2550 1216Fuel particle size (mm) 05 1
Limestone (g/s) 01.5 01Limestone particle size (ξm) 0500 0500
Total combustion air (Nl/min) 6001100 278Secondary air (Nl/min) 0500 83
Tertiary air (Nl/min) 0200 56Additional gases N2, CO2, O2, H2O can be mixed with combustion airAdditive feeders liquid spraying system with gas atomising, solid powder additive feeder
Option for oxyfuel combustion in CFB fuel power up to 100 kW, additional bed heat exchanger
Conditions: CFB BFBTemperature (oC) 700950 8701100
Bed pressure (Pa) 20003500 2000Fluidization velocity (m/s) 12.5 0.5
Total gas velocity (m/s) 2.54 0.6Gas recidence time (s) 24 8
Circulation (kg/m2s) 16
Measurements for CFB and BFB:Flue gas composition O2 (0100%), CO2 (0100%), CO (05000ppm), NO (01000ppm), SO2 (05000ppm)
FTIR spectrometer H2O, CO2, CO, NO, NO2, N2O, NH3, SO2, HCl, CH4, C2H2, C2H4, C2H6
Ash samples bottom ash, fly ash and circulation in CFBHeat transfer probes (number) 3
Quenched gassolid sampling probe (number) 1Deposit probe (number) 2, tubular rings (L = 3540 mm, D in = 10 mm, Dout = 16 mm)
Additional measurements fine particles (DLPI, ELPI), heavy metals
Typical operational parameters for Bench scale (CFBBFB)
Dimensions of furnace:Height (mm) 610
Diameter (mm) 32.8Feeds:
Continuous fuel/additive feed (g/min) 12.5Fuel batch feed (g) 0.52
Fuel power (kW) 0.252PSD for continuous fuel/additive feed (mm) 0.251
PSD for batch fuel/additive feed (mm) 02Total combustion air (Nl/min) 0120
Secondary air (Nl/min) 06Additional gases N2 and bottle gases: e.g. CO2, O2, SO2, NO, CO can be mixed with combustion air
Conditions:Temperature ( oC) 7501050
Bed pressure (Pa) 1503000Fluidization velocity (m/s) 0.55
Total gas velocity (m/s) 0.55Gas recidence time (s) 0.121.2
Measurements:Flue gas composition O2 (0100%), CO2 (0100%), CO (05000ppm), NO (01000ppm), SO2 (05000ppm)
FTIR spectrometer H2O, CO2, CO, NO, NO2, N2O, NH3, SO2, HCl, CH4, C2H2, C2H4, C2H6
Ash samples bottom ash, fly ash, circulation
Schematic diagram of the laboratoryscale bubbling fluidized bed reactor
Additional information
Dr Jouni Hämäläinen,[email protected]. +358 20 722 2529http://www.vtt.fi
Dr Martti Aho,[email protected]. +358 20 722 2545
Mr. Pasi Vainikka,[email protected]. +358 20 722 2514
Mr. Antti Tourunen,[email protected]. +358 20 722 2718
CFB and Bench scale reactors BFB reactor
The fluidised bed erosion tester has been build from a commercial electrically heated fluidised bed having a total height of 950 mm andinner diameter of about 400 mm. The actual test rig consists of two horizontal arms rotated by two concentric vertical axe counterwisewithin the fluidised bed.
FLUIDISED BED EROSION TESTER
The mass loss behaviour of AISI 316 samples testedat two different temperatures at identical upperarmsample placement "A”
Erosion of AISI 316 samples (Location A)
00.050.1
0.150.2
0.25
0 50 100 150
Exposure time [h]
T= 500 CT=400 C
Typical operational parameters for FB ErosionTester
Dimensions of furnace:Hight (mm) 950
Diameter (mm) 400Sample material tubular rings (L =15 mm, D in = 15 mm, Dout = 25 mm), max number 16
Conditions:Bed temperature (oC) 400500
Bed material aluminium oxide, mean grain size 0.22 mmFixed bed height (mm) 660
Fluidized bed height (mm) 40Rotation speed (1/min) 270
Relative velocity of sand particles (m/s) 1.23.5Typical test run time (h) 100
Analyses:Mass loss curves
SEM/EDSAtomic force microscopy
Schematic view of the fluidised bed erosion tester.
Motor
Gearbox
Cover