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Li, H., Larsson, E. K., Thorin, E., Dahlquist, E. & Yu, X. (2015). Feasibility study on combining anaerobic digestion and biomass gasification to increase the production of biomethane. Energy Conversion and Management, 100, 212-219
Open this publication in new window or tab >>Feasibility study on combining anaerobic digestion and biomass gasification to increase the production of biomethane
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2015 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 100, p. 212-219Article in journal (Refereed) Published
Abstract [en]

There is a rapid growing interest in using biomethane as fuel for transport applications. A new concept is proposed to combine anaerobic digestion and biomass gasification to produce biomethane. H-2 is separated from the syngas generated by biomass gasification in a membrane system, and then is used to upgrade raw biogas from anaerobic digestion. Simulations have been conducted based on the real operation data of one full scale biogas plant and one full scale biomass gasification plant in order to investigate the feasibility of the new concept. Results show that although less power and heat are generated compared to the gasification plant, which results in a lower overall efficiency, much more biomethane can be produced than the biogas plant; and the new concept can achieve a higher exergy efficiency. Due to the increasing price of biomethane, the novel concept demonstrates a big potential of income increase. For example, at a biomethane price of 12.74SEK/kg, the annual income can be increased by 53% compared to the total income of the biogas and gasification plant. (C) 2015 Elsevier Ltd. All rights reserved.

Keywords
Anaerobic digestion, Biomass gasification, Biomethane production, Biofuel, Biogas upgrading, Membrane gas separation
National Category
Energy Engineering
Identifiers
urn:nbn:se:mdh:diva-28617 (URN)10.1016/j.enconman.2015.05.007 (DOI)000356754700023 ()2-s2.0-84929620607 (Scopus ID)
Available from: 2015-07-16 Created: 2015-07-16 Last updated: 2018-02-22Bibliographically approved
Dahlquist, E., Mirmoshtaghi, G., Larsson, E. K., Thorin, E., Yan, J., Engvall, K., . . . Lu, Q. (2015). Modelling and Simulation of Biomass Conversion Processes. In: Proceedings - 8th EUROSIM Congress on Modelling and Simulation, EUROSIM 2013: . Paper presented at 8th EUROSIM Congress on Modelling and Simulation, Cardiff 9-13 September 2013 (pp. 506-512). , Article ID 7004995.
Open this publication in new window or tab >>Modelling and Simulation of Biomass Conversion Processes
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2015 (English)In: Proceedings - 8th EUROSIM Congress on Modelling and Simulation, EUROSIM 2013, 2015, p. 506-512, article id 7004995Conference paper, Published paper (Refereed)
Abstract [en]

By utilizing biomass gasification, the energy contentof the biomass can be utilized to produce gas to be used forcogeneration of heat and power as well as other energy carrierssuch as fuels for vehicles. The concept is suitable forapplication to existing CHP plants as well as for utilizing spentliqour in small scale pulp and paper mills. The introductionwould enable flexible energy utilization, use of problematicfuels as well as protects the environment by e.g. avoiding therelease of toxic substances. In this paper, the possibilities todevelop this concept is discussed. In this paper we comparedifferent gasification processes with respect to what gas qualitywe get, and how the gasification can be modelled usingdifferent modelling approaches, and how these can becombined. Results from simulations are compared toexperimental results from pilot plant operations in differentscales and with different processes like CFB and BFBTechnologies, athmospheric and pressurized, and using steam,air and oxygen as oxidizing media.

Keywords
Biomass, gasification, modelling, simulation, CHP, agricultural residue
National Category
Energy Systems
Research subject
Energy- and Environmental Engineering
Identifiers
urn:nbn:se:mdh:diva-21749 (URN)10.1109/EUROSIM.2013.91 (DOI)000361021500088 ()2-s2.0-84929593503 (Scopus ID)9780769550732 (ISBN)
Conference
8th EUROSIM Congress on Modelling and Simulation, Cardiff 9-13 September 2013
Available from: 2013-10-01 Created: 2013-10-01 Last updated: 2020-02-20Bibliographically approved
Larsson, E. K. & Dahlquist, E. (2013). Separation of methane.
Open this publication in new window or tab >>Separation of methane
2013 (English)Report (Other academic)
Abstract [en]

Gasification with gas cleaning and direct separation of methane, where the residual gas can be used in a conventional boiler, is an attractive scenario in regard to flexible production of methane, power and heat. The technological challenge is to separate methane from a product gas with a low methane content and also complex composition.

Membranes have several attractive properties for this application. They consume no energy input for their operation, as long as the feed is pressurized and no recirculation etc. is needed. They have attracted a great deal of interest in the last decades for separation of methane and carbon dioxide from anaerobic digestion biogas production and for treatment of natural gas. They have the potential to offer cost effect­tive solutions also for smaller plants, since they are delivered in modules that can be duplicated to fit the size of the plant. For these reasons, it was chosen to concentrate the study on membranes. Alternative separation methods that were considered are cryogenic separation and pressure swing adsorption (PSA).

Membranes separate gases based on differences in gas components’ diffusivity and solubility in the (polymer) membrane material. It was found that both these factors differ too little between CH4 and N2 to assume a possibility to separated them, if N2 is a large part of the gas composition, as is the case in air-blown gasification. Therefore, it was concluded that membrane separation is not an option for air-blown gasification. Instead, a gas from oxygen-blown CFB gasification or from dual bed indirect gasification was set as the input gas, thereby eliminating the problem with N2 in the search for suitable membranes. The main components in the gas are then H2, CO, H2O, CO2, CH4 and some higher hydrocarbon. An ideal separation would yield only CH4 and higher hydrocarbons in one stream and the other components in another.

There are two kinds of membranes, glassy, that separate mainly based on size, and rubbary, that separate mainly based on solubility which is closely connected to the boiling point of the gas components. Calculations were made on a typical glassy membrane. It was found that the problem is that the separation between CH4 and CO is insufficient. Therefore, a two-step membrane separation with a shift step between was tried. The shift reaction, CO + H2O -> H2 + CO2, introduces a gas composition to the second membrane that is more easily separated. Even with the possibly overoptimistic conditions set in this preliminary calculation, the result is unsatisfactory. The achieved CH4 percentage is only 80% and 30% of the methane is lost in the gas streams that will be combusted for heat and power production. Also, this separation option would require a rather complicated process. The conclusion is that it is unlikely that this concept would be attractive, even after modifications to achieve better percentage values. 

Rubbary membranes have also been considered. Based on the separation factors, it can be conclu­ded that they would require upstream separation of H2O and CO2 by a glassy membrane or other gas processing methods, before a rubbary membrane could perform the separation between CH4 and H2+CO. It is, however, unlikely that this separation would be sufficiently good, at least in a one-step system.

A possible way to increase performance of membranes is to use liquid membranes that has a liquid to absorb gas components that have permeated through the membrane. No publications have been found on specific liquid membranes that could be suitable for the separation in question. Liquid membranes intrinsically add the need for regeneration of the liquid phase. Further search for liquid membranes is assessed as one of the interesting routes for continued investigations on separation. 

Cryogenic separation can be expected to fulfil the requirements on gas quality and minimizing CH4 loss. The drawback is that a cryogenic plant would mean substantial investment cost and energy consumption. A conclusion from a rough cost analysis is that the cryogenic alternative seems to have the potential to be cost effective and should be included in further studies.

Liquid membranes, cryogenic and also PSA etc. are all worth considering for the separation process.

Publisher
p. 15
Keywords
gasification, biomass, gas separation, methane, membrane, glassy membrane, rubbary membrane, product gas, water gas shift
National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-23890 (URN)
Projects
Svensk Förgasningcentrum, SFC, Node SGV-CDGB
Funder
Swedish Energy Agency
Available from: 2013-12-20 Created: 2013-12-20 Last updated: 2015-11-13Bibliographically approved
Larsson, E. K. & Knoef, H. (2009). Gas Treatment. In: A. V. Bridgwater, H. Hofbauer, S. van Loo (Ed.), Thermal Biomass Conversion: (pp. 177-188). Newbury, United Kingdom: CPL Press, CPL Scientific Publishing Services Ltd
Open this publication in new window or tab >>Gas Treatment
2009 (English)In: Thermal Biomass Conversion / [ed] A. V. Bridgwater, H. Hofbauer, S. van Loo, Newbury, United Kingdom: CPL Press, CPL Scientific Publishing Services Ltd , 2009, p. 177-188Chapter in book (Refereed)
Place, publisher, year, edition, pages
Newbury, United Kingdom: CPL Press, CPL Scientific Publishing Services Ltd, 2009
Keywords
gasification, pyrolysis, biomass, gas treatment, gas cleaning, tar, thermal impregnation, OLGA, Güssing, reforming, water gas shift, PyRos
National Category
Engineering and Technology
Identifiers
urn:nbn:se:mdh:diva-23887 (URN)978-1-872691-53-4 (ISBN)
Projects
ThermalNet
Available from: 2013-12-20 Created: 2013-12-20 Last updated: 2013-12-20Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5559-4983

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