University of Seville. 19 th FBC Conference Pilot plant experiences with fluidised bed gasification of orujillo and MBM 19th FBC Conference, Session B3 23 May 2006 Vienna, Austria Gómez-Barea A., Campoy M., Ollero P., Fernández-Pereira C. Chemical and Environmental Department University of Seville Spain 19th FBC Conference The International Conference on Fluidized Bed Combustion May 21 – 24, 2006, Vienna, Austria
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University of Seville. 19th FBC Conference
Pilot plant experiences with fluidised bed gasification of orujillo and MBM
19th FBC Conference, Session B323 May 2006
Vienna, Austria
Gómez-Barea A., Campoy M., Ollero P., Fernández-Pereira C.Chemical and Environmental Department
University of Seville Spain
19th FBC ConferenceThe International Conference on Fluidized Bed Combustion
May 21 – 24, 2006, Vienna, Austria
University of Seville. 19th FBC Conference
Content
1. Introduction2. Objectives3. Experimental4. Analysis of pilot plant performance 5. Ash characterisation6. Methods for fly-ash utilisation 7. Utilisation options for the produced fly ash8. Conclusions
University of Seville. 19th FBC Conference
1. Introduction
• Atmospheric air gasification of biomass and waste in a BFB reactor is a simple and cheap process
• Classical analysis is focussed on the LHV and quality of the producer gas.
• A key factor limiting gasification is fly ash quality, especially the carbon content of the ash.
• Fly ash from the gasification of biomass differs considerable from conventional combustion ash1. unburned carbon is much higher, typically 10–60% w.w.2. It contains PAH and in case of waste gasification
chlorine and heavy metals. • Issues 1 and 2 make the management of gasification fly ash
a challenging task – Difficult recycle or utilisation
1. Introduction
University of Seville. 19th FBC Conference
Introduction (cont.)
• An increase in carbon conversion results in:– higher efficiency direct positive influence on power
production efficiency– higher possibility to recycle or use of ashes as raw
material in other processes. • An essential part of BFB gasification is to optimise
operation to improve ash quality (especially to reduce carbon content)
• This will facilitate the development of sustainable economical methods for ash management
1. Introduction
University of Seville. 19th FBC Conference
Objectives of this work
• Assess the impact of:– operating conditions – bed material and additives
on the gas quality and the ash quality. • Discuss the impact of the ash quality on:
– potential utilisation options of the ashes– economics of their future utilisation
• Present experience acquired by gasifying – two fuels: orujillo and MBM – in a 150 kWth BFB pilot plant
2. Objectives
University of Seville. 19th FBC Conference
3. Experimental. Materials
• Fuels– orujillo – MBM
• Bed materials and additives– silica sand – ofite – Lime– Limestone
3. Experimental
University of Seville. 19th FBC Conference
Test facility
3. Experimental
Gasifier
Screw feederHigh-speed screw
Hoppers
Flexible
27 kWe Oven
After Burner
Ashtray
Preheater
Outlet gas
Scrubber
Cyclones
Filters
To Water Treatment
Water
To Stack
Propane
Isolation Blanket
Preheater
Water
Steam generator
Overflow
University of Seville. 19th FBC Conference
Technical and operating data of pilot plant facility
3. Experimental
Inside bed diameter 0.15 m Bed height 1.7 m Inside freeboard diameter 0.25 m Freeboard height 2.5 m Fluidisation velocity 0.8 – 1.4 m/s Bed material Ofite, limestone Fuel Orujillo, MBM Fuel feed rate 6 – 35 kg/h Gasification agent Air Operating temperature 700 – 850ºC Operating pressure Atmospheric Fluidisation regime Bubbling Maximum thermal capacity 150 kWth
University of Seville. 19th FBC Conference
4. Analysis of pilot plant performance
4. Analysis of pilot plant performance
• Orujillo tests: – Severe sintering using silica sand > 750ºC No valid
data– Ofite solved sintering up to 830 ºC– Good quality of producer gas (LHV=5 MJ/Nm3)– Optimum for gasification efficiency at ER=0.25 (0.17 ,
0.31)– Carbon conversion 90% – High carbon content and Chlorine in ash (also
Chromium)
University of Seville. 19th FBC Conference
Optimisation with orujillo
70.0
72.0
74.0
76.0
78.0
80.0
82.0
84.0
86.0
88.0
0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32ER
Car
bon
conv
ersi
on (%
)
45.0
50.0
55.0
60.0
65.0
70.0
0.16 0.18 0.20 0.22 0.24 0.26 0.28 0.30 0.32
ER
Gas
ifica
tion
effic
ienc
y
– Optimisation:• Constrained by sintering• Aceptable carbon conversion with maximun
efficiency4. Analysis of pilot plant performance
University of Seville. 19th FBC Conference
4. Analysis of pilot plant performance
4. Analysis of pilot plant performance
• MBM tests: – Pelletisation was necessary (feeding problems)– Poor gas quality (LHV<3 MJ/Nm3)– Very high carbon conversion (~98%)– Low carbon content and volume of ash– Additives improve gas quality but little effect
upon ash quality
University of Seville. 19th FBC Conference
Synergy of the fuels
• Poor gas quality for MBM due to diluting effect (very low O/C content)
• Good synergy of the two fuels: Blends of orujillo + MBM – acceptable O/C– acceptable flowing properties without pelletisation
0.50
1.00
1.50
2.00
2.50
3.00
0.15 0.2 0.25 0.3 0.35
ER
AR (N
m3/
kg)
Tyre Coal MBMWood
Straw
Rice huskOrujillo
0.50
1.00
1.50
2.00
2.50
3.00
0.15 0.2 0.25 0.3 0.35
ER
AR (N
m3/
kg)
Tyre Coal MBMWood
Straw
Rice huskOrujillo
4. Analysis of pilot plant performance
University of Seville. 19th FBC Conference
5. Ash characterisation
5. Ash characterisation
Basic ash characterisation– Physical analysis: density and PSD– Elemental and ultimate analysis
• Further characterisation (necessary for the screening of existing utilisation options )– Trace elements (ASTM D-3683)– Ashes leachability
• DIN 38414 • TCLP (USEPA 1311)• compliance batch leaching test EN 12457/1-4 • Up-flow percolation test EN 14405 (colum test)
– Analysis of Eluates (metals) – Thermal analysis (TGA, DSC, DTA)– Other: PAH, and specific for a given route being tested
5. Ash characterisation
University of Seville. 19th FBC Conference
6. Methods for fly-ash utilisation
Three main utilisation categories can be identified 1. Use as fuel:
– co-firing in coal/biomass-fired power plants; – firing in a dedicated boiler; – replacement fuel in smelters/incinerators – firing in cement kiln;
2. Use in construction: • Fine applications: cement replacement in concrete. • Less stringent applications:
– soil stabilization– road base – structural fill (filler in asphalt, asphalt-like products)– lightweight bricks
3. Use in agriculture: directly as fertilizer or as soil improver.
6. Methods for fly-ash utilisation
University of Seville. 19th FBC Conference
7. Utilisation options for the produced fly ash
• High carbon content of ashes (especially orujillo) limits applications
• Construction– Fine applications in fully violated (carbon content and Cl)– Other: plausible
• Fertiliser: – MBM: ash often considered attractive for fertilisers
• the high PAH content found in this work make difficult this application.
• low solubility of P and Ca make the attractiveness of this routedoubtful (for common soils).
• TCLP tests showed acceptable solubility for P and Ca acid soils – Orujillo: soil amendment (PAH limit)– Most probably pretreatment necessary
7. Utilisation options for the produced fly ash
University of Seville. 19th FBC Conference
Utilisation options for the produced fly ash
• Application as fuel– Cl, TOC and PSD limits– Co-combustion in existing boilers reasonable but plant
owner refused these ashes– Fuel in cement kilns
• Mixed with the fuel (in the burners). • Other options are limited by:
– TOC (with the raw material) – PSD (in the combustion chamber)
– Pelletisation of ash (depends of the actual LHV). • Non feasible for this ash but acceptable for full-scale ashes like
Ammer and Lahti full-scale gasifies (15-20 MJ/kg)
7. Utilisation options for the produced fly ash
University of Seville. 19th FBC Conference
Further options for the produced fly ash
• We have investigated more advanced options with promising results– Stabilisation/Solidification (S/S)– Use in lightweight construction boards
• low-cost moulding and curing methods• ash percentages up to 60%w/w• Gypsum and additives (vermiculite and fibre)
– Use in bricks manufacture• Ash content in bricks up to 20%• Bricks with special insulating thermal and acoustic properties
7. Utilisation options for the produced fly ash
University of Seville. 19th FBC Conference
8. Conclusions
• We made a technical assessment of MBM and orujillo by long-term test trials in FB at pilot scale
• Orujillo is a good feedstock for FB gasification while MBM produces poor gas
• High carbon conversion achieved with MBM while orujillo is severe limited by sintering
• Optimisation of orujillo was optimised to achivelong enough tests
• Synergy of fuels seems rather attractive: under current investigation
8. Conclusions
University of Seville. 19th FBC Conference
8. Conclusions (cont.)
• Ash limited by chlorine (orujillo) and carbon content (both)
• In general, direct ash utilisation is difficult• Fertiliser seems reasonable option with pretreatment
(oxidation and/or leaching) • Fuel in cement kilns mixed with the fuel (in the
burners) very promising without pretreatment (prices have to compete with other fuels)
• New utilisation routes have been investigated: bricks with thermal and acoustic properties and lightweight construction boards. Promising results but they are still under further testing
8. Conclusions
University of Seville. 19th FBC Conference
Thank you for your attention
Questions are most welcome
University of Seville. 19th FBC Conference
Pilot plant experiences with fluidised bed gasification of orujillo and MBM
19th FBC Conference, Session B323 May 2006
Vienna, Austria
Gómez-Barea A., Campoy M., Ollero P., Fernández-Pereira C.Chemical and Environmental Department
University of Seville Spain
19th FBC ConferenceThe International Conference on Fluidized Bed Combustion