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Generation of synthesis gas for fuels and chemicals production

Tunå, Per LU (2013)
Abstract (Swedish)
Popular Abstract in Swedish

Dagens samhälle är mycket beroende av fordonsbränslen och kemikalier som producerats av råolja. Framtidens tillgång på råolja är oviss, det enda som är säkert är att det är en ändlig resurs. Användningen av olja bidrar dessutom till koldioxidutsläpp till atmosfären. För att säkra framtida tillförsel av energi och kemikalier till samhället och för att uppnå ett mer klimatneutralt samhälle behöver råoljan ersättas med förnybara och hållbara råvaror. Förädlingen av biomassa till drivmedel och kemikalier är ett av alternativen för att uppnå ett fossilfritt samhälle. Förädlingen kan ske antingen via termokemisk eller via biokemisk omvandling. Den termokemiska omvandlingen är den mest flexibla med... (More)
Popular Abstract in Swedish

Dagens samhälle är mycket beroende av fordonsbränslen och kemikalier som producerats av råolja. Framtidens tillgång på råolja är oviss, det enda som är säkert är att det är en ändlig resurs. Användningen av olja bidrar dessutom till koldioxidutsläpp till atmosfären. För att säkra framtida tillförsel av energi och kemikalier till samhället och för att uppnå ett mer klimatneutralt samhälle behöver råoljan ersättas med förnybara och hållbara råvaror. Förädlingen av biomassa till drivmedel och kemikalier är ett av alternativen för att uppnå ett fossilfritt samhälle. Förädlingen kan ske antingen via termokemisk eller via biokemisk omvandling. Den termokemiska omvandlingen är den mest flexibla med avseende på möjliga produkter och har dessutom högre verkningsgrad. Termokemisk omvandling av

biomassa, som kan vara träflis eller jordbruksrester, kan användas för att producera syntetiska fordonsbränslen, plaster och gummi. En av de termokemiska omvandlingsprocesserna börjar med en förgasare som producerar en energirik gas som kallas syntesgas vilken sedan kan användas för att syntetisera flytande eller gasformiga produkter. Produktgasen från förgasaren innehåller förutom kolmonoxid och vätgas även kolväten, tjäror, koldioxid, vatten samt en del andra föroreningar. Av föroreningarna i gasen är tjärorna det största problemet då de kan förstöra värmeväxlare och annan utrustning.

I detta arbete studerades bland annat apparatur som kan öka verkningsgraden i förädlingen av biomassa till produkter såsom drivmedel och kemikalier. Högre verkningsgrader i processerna leder till mer produkt per råvara och därmed lägre specifika produktionskostnader. En av arbetets huvuddelar är fokuserat på

utrustning för att omvandla tjäror och andra kolväten i gas producerad av en förgasare. Den här delen består dels av experimentellt arbete utfört på Institutionen för Kemiteknik och av datormodeller. Resultaten visar på mycket hög omsättning av föroreningarna i gasen med en hög energieffektivitet. Processerna som används i omvandlingen av biomassa till fordonsbränslen och kemikalier används idag till stor del i naturgasbaserade anläggningar för framställning av bland annat metanol, ammoniak och råmaterial för

plasttillverkning. För att biomassabaserad tillverkning ska kunna konkurera med naturgasbaserad tillverkning och för att använda en begränsad råvara på bästa sätt krävs hög verkningsgrad i processerna.

Datormodeller över tillverkningsanläggningar för framställning av drivmedel och kemikalier kan användas för att beräkna hur mycket produkt som kan produceras från en given mängd råvara, verkningsgrad och vad produktionskostnaden blir för produkten. Ett flertal modeller har konstruerats och använts i detta arbete för att utreda verkningsgrader och kostnader för framställning av olika drivmedel och

kemikalier. Tillverkning av följande produkter har studerats; metanol, dimetyleter, syntetisk bensin, syntetisk diesel, syntetisk naturgas samt ammoniak. Resultaten visar att den termokemiska omvandlingen till syntetiska fordonsbränslen har en betydligt högre energiverkningsgrad än etanol tillverkad via biokemisk omvandling

av träflis. Samtliga fordonsbränslen tillverkade via termokemisk omvandling har dessutom en lägre produktionskostnad än etanol framställt via biokemisk omvandling. Produktionen av ammoniak från förnyelsebara råvaror har också studerats och visar på en produktionskostnad som kan konkurera med fossilbaserad

ammoniak. Resultaten av det här arbetet visar på att förnyelsebara fordonsbränslen och kemikalier kan vara konkurrenskraftiga med dagens fossilbaserade alternativ. (Less)
Abstract
Many scientists believe that the oil production will peak in the near future, if the peak has not already occurred. Peak oil theories and uncertain future oil deliveries have stimulated interest in alternative sources of fuel and chemicals. This interest has been enhanced by concerns about energy security and about the climate change caused by emissions of carbon dioxide. The result has been increased interest in substituting fossil fuels with renewable energy sources such as wind, solar and biomass. However, this has proved particularly difficult in the transportation sector.



The most likely source of renewable hydrocarbon fuels for transportation is biomass. It comes in many forms, none of which are suitable for direct... (More)
Many scientists believe that the oil production will peak in the near future, if the peak has not already occurred. Peak oil theories and uncertain future oil deliveries have stimulated interest in alternative sources of fuel and chemicals. This interest has been enhanced by concerns about energy security and about the climate change caused by emissions of carbon dioxide. The result has been increased interest in substituting fossil fuels with renewable energy sources such as wind, solar and biomass. However, this has proved particularly difficult in the transportation sector.



The most likely source of renewable hydrocarbon fuels for transportation is biomass. It comes in many forms, none of which are suitable for direct use in internal combustion engines and gas turbines. Thus the biomass has to be refined to convert its energy into a more usable form. The most versatile conversion of biomass is thermochemical conversion via gasification and downstream synthesis,

which allows the production of both fuels and chemicals.



In the biomass gasification process, a gasifier converts the solid biomass into a gaseous product known as producer gas. The producer gas contains the desired components carbon monoxide and hydrogen, but it also contains water, carbon dioxide, lower hydrocarbons, tars and impurities that need to be removed from the gas. Reforming the tars and hydrocarbons in producer gas is difficult because of the amount of sulphur present.



This thesis investigates the use of reverse-flow reactors to reform the tars and hydrocarbons in biomass generated producer gas.. Reverse-flow reactors operate by periodically reversing the direction of flow to enable high levels of heat recovery. The high heat recovery enables non-catalytic reformers to be operated at efficiencies near that of catalytic reformers. The operation of reverse-flow reactors is investigated experimentally in a tar-cracking reactor using dolomite as bed material and also theoretically using computer models. The investigations show that reverse-flow reactors have great potential, offering a chemically robust alternative to conventional reformers when operating on sulphur-containing biomass-generated producer gas. Furthermore, operation of reverse-flow tar crackers using dolomite as bed material is an efficient and viable solution for tar removal and syngas boosting.



The producer gas also contains ammonia in varying amounts depending on the gasifier’s operating parameters and feedstock. Ammonia can be a poison for catalysts and, if the producer gas is burnt, will produce elevated levels of NOX in the flue gas. The selective catalytic oxidation of ammonia in synthesis gas was thus also investigated by experiments on a model synthesis gas. This thesis also covers mass and energy balance calculations to determine the

efficiency and economics of synthetic fuels and chemicals plants. Several possible plant configurations were investigated, both stand-alone and integrated. The integration of a pulp and paper mill with a fuel synthesis plant is a very likely scenario as the biomass logistics are already located on-site. Another possible integration scenario involves steel plants, where large quantities of energy-rich gases are handled as off-gases in coke production. Utilisation of this off-gas coupled with biomass gasification was also investigated.

In the stand-alone plants, the difference between reverse-flow reformers and conventional non-catalytic reformers was investigated as front-ends to well-head gas upgrading to produce crude oil via the Fischer-Tropsch synthesis. Furthermore a well-to-wheel comparison of synthetic natural gas, methanol, ethanol, dimethyl ether, Fischer-Tropsch diesel and synthetic gasoline was performed. The comparison used woody biomass as feedstock and computed mass and energy balances for complete plants from gasifier to fuel as well as for lignocellulosic ethanol production by fermentation. Efficiency in regard to feedstock to travel distance (Well-to-Wheel) and the cost of transportation was also investigated. Ammonia is one of the most valuable chemicals for modern agriculture. Current production is almost entirely based on fossil fuels. Thus small-scale production of

ammonia from renewable feedstocks was also investigated. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • van der Meijden, Christiaan, Bimass Energy Engineering, The Netherlands
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Synthetic fuels and chemicals, gasification, gas conditioning, simulation, tar-cracking
pages
252 pages
defense location
Hörsal K:B, Centre for Chemistry and Chemical Engineering, Getingevägen 60, Lund
defense date
2013-05-31 13:15
ISBN
978-91-7422-321-7
language
English
LU publication?
yes
id
303df7ce-9145-44f7-8a13-cdc54a6225d8 (old id 3732069)
date added to LUP
2013-05-06 10:22:38
date last changed
2016-09-19 08:45:17
@misc{303df7ce-9145-44f7-8a13-cdc54a6225d8,
  abstract     = {Many scientists believe that the oil production will peak in the near future, if the peak has not already occurred. Peak oil theories and uncertain future oil deliveries have stimulated interest in alternative sources of fuel and chemicals. This interest has been enhanced by concerns about energy security and about the climate change caused by emissions of carbon dioxide. The result has been increased interest in substituting fossil fuels with renewable energy sources such as wind, solar and biomass. However, this has proved particularly difficult in the transportation sector.<br/><br>
<br/><br>
The most likely source of renewable hydrocarbon fuels for transportation is biomass. It comes in many forms, none of which are suitable for direct use in internal combustion engines and gas turbines. Thus the biomass has to be refined to convert its energy into a more usable form. The most versatile conversion of biomass is thermochemical conversion via gasification and downstream synthesis,<br/><br>
which allows the production of both fuels and chemicals.<br/><br>
<br/><br>
In the biomass gasification process, a gasifier converts the solid biomass into a gaseous product known as producer gas. The producer gas contains the desired components carbon monoxide and hydrogen, but it also contains water, carbon dioxide, lower hydrocarbons, tars and impurities that need to be removed from the gas. Reforming the tars and hydrocarbons in producer gas is difficult because of the amount of sulphur present.<br/><br>
<br/><br>
This thesis investigates the use of reverse-flow reactors to reform the tars and hydrocarbons in biomass generated producer gas.. Reverse-flow reactors operate by periodically reversing the direction of flow to enable high levels of heat recovery. The high heat recovery enables non-catalytic reformers to be operated at efficiencies near that of catalytic reformers. The operation of reverse-flow reactors is investigated experimentally in a tar-cracking reactor using dolomite as bed material and also theoretically using computer models. The investigations show that reverse-flow reactors have great potential, offering a chemically robust alternative to conventional reformers when operating on sulphur-containing biomass-generated producer gas. Furthermore, operation of reverse-flow tar crackers using dolomite as bed material is an efficient and viable solution for tar removal and syngas boosting.<br/><br>
<br/><br>
The producer gas also contains ammonia in varying amounts depending on the gasifier’s operating parameters and feedstock. Ammonia can be a poison for catalysts and, if the producer gas is burnt, will produce elevated levels of NOX in the flue gas. The selective catalytic oxidation of ammonia in synthesis gas was thus also investigated by experiments on a model synthesis gas. This thesis also covers mass and energy balance calculations to determine the<br/><br>
efficiency and economics of synthetic fuels and chemicals plants. Several possible plant configurations were investigated, both stand-alone and integrated. The integration of a pulp and paper mill with a fuel synthesis plant is a very likely scenario as the biomass logistics are already located on-site. Another possible integration scenario involves steel plants, where large quantities of energy-rich gases are handled as off-gases in coke production. Utilisation of this off-gas coupled with biomass gasification was also investigated.<br/><br>
In the stand-alone plants, the difference between reverse-flow reformers and conventional non-catalytic reformers was investigated as front-ends to well-head gas upgrading to produce crude oil via the Fischer-Tropsch synthesis. Furthermore a well-to-wheel comparison of synthetic natural gas, methanol, ethanol, dimethyl ether, Fischer-Tropsch diesel and synthetic gasoline was performed. The comparison used woody biomass as feedstock and computed mass and energy balances for complete plants from gasifier to fuel as well as for lignocellulosic ethanol production by fermentation. Efficiency in regard to feedstock to travel distance (Well-to-Wheel) and the cost of transportation was also investigated. Ammonia is one of the most valuable chemicals for modern agriculture. Current production is almost entirely based on fossil fuels. Thus small-scale production of<br/><br>
ammonia from renewable feedstocks was also investigated.},
  author       = {Tunå, Per},
  isbn         = {978-91-7422-321-7},
  keyword      = {Synthetic fuels and chemicals,gasification,gas conditioning,simulation,tar-cracking},
  language     = {eng},
  pages        = {252},
  title        = {Generation of synthesis gas for fuels and chemicals production},
  year         = {2013},
}