Modelling of torrefaction and hydrothermal carbonization and heat integration of torrefaction with a CHP plant
Sermyagina, Ekaterina (2016-12-09)
Väitöskirja
Sermyagina, Ekaterina
09.12.2016
Lappeenranta University of Technology
Acta Universitatis Lappeenrantaensis
Julkaisun pysyvä osoite on
https://urn.fi/URN:ISBN:978-952-335-013-7
https://urn.fi/URN:ISBN:978-952-335-013-7
Tiivistelmä
Biomass provides an excellent opportunity to increase the use of local resources and promote
renewable energy generation. The considerable diversity of biomass materials and differences
in their chemical structure require detailed evaluation of their properties and impact on the
conversion processes. The unstable quality of untreated biomass poses certain problems for
biomass utilization in a large scale. Hydrothermal carbonization and torrefaction present two
possible ways of improving the characteristics of biomass. Comprehensive understanding and
evaluation of all the influencing factors of these relatively novel methods is crucial for the
development of the processes.
This thesis describes the results of chemical analysis of nine biomasses with respect to
thermochemical conversion: the impact of chemical components on thermal decomposition is
evaluated. The performance of any conversion process depends not only on biomass properties
but also on the process characteristics, and that is why the effect of the main reaction parameters
on mass and energy yields during hydrothermal carbonization and torrefaction of coniferous
biomass is studied experimentally and expressed with mathematical correlations. Since both
processes require a certain amount of heat to be supplied, the development of the technologies
in a large scale by means of heat integration with combined heat and power (CHP) plants has
significant potential. A model of a torrefaction unit is developed and integrated with two
different-sized CHP plants. The mutual effects of the torrefaction process and the operational
mode of the CHP plant on the thermodynamic performance of the integrated plant are
investigated with six integration scenarios. The analysis reveals notable differences in the
impact of torrefaction-CHP integration at different operational modes of the CHP plant, and
the influence of seasonal variations in the operation of a CHP backpressure plant is analyzed
in detail with a developed multiperiod model. Profitability evaluation of the integrated
schemes, together with stand-alone and co-located CHP and torrefaction plants make it possible
to assess the economic potential of the integration. This study indicates that the heat integration
of torrefaction and a CHP plant can be economically profitable over co-located plants
(particularly for the integration options with the longest operation time). Additionally, this
work assesses the main economic factors for the profitability of integrated plants and confirms
the importance of detailed operational and economic analyses for the assessment of the
potential of the integration options.
renewable energy generation. The considerable diversity of biomass materials and differences
in their chemical structure require detailed evaluation of their properties and impact on the
conversion processes. The unstable quality of untreated biomass poses certain problems for
biomass utilization in a large scale. Hydrothermal carbonization and torrefaction present two
possible ways of improving the characteristics of biomass. Comprehensive understanding and
evaluation of all the influencing factors of these relatively novel methods is crucial for the
development of the processes.
This thesis describes the results of chemical analysis of nine biomasses with respect to
thermochemical conversion: the impact of chemical components on thermal decomposition is
evaluated. The performance of any conversion process depends not only on biomass properties
but also on the process characteristics, and that is why the effect of the main reaction parameters
on mass and energy yields during hydrothermal carbonization and torrefaction of coniferous
biomass is studied experimentally and expressed with mathematical correlations. Since both
processes require a certain amount of heat to be supplied, the development of the technologies
in a large scale by means of heat integration with combined heat and power (CHP) plants has
significant potential. A model of a torrefaction unit is developed and integrated with two
different-sized CHP plants. The mutual effects of the torrefaction process and the operational
mode of the CHP plant on the thermodynamic performance of the integrated plant are
investigated with six integration scenarios. The analysis reveals notable differences in the
impact of torrefaction-CHP integration at different operational modes of the CHP plant, and
the influence of seasonal variations in the operation of a CHP backpressure plant is analyzed
in detail with a developed multiperiod model. Profitability evaluation of the integrated
schemes, together with stand-alone and co-located CHP and torrefaction plants make it possible
to assess the economic potential of the integration. This study indicates that the heat integration
of torrefaction and a CHP plant can be economically profitable over co-located plants
(particularly for the integration options with the longest operation time). Additionally, this
work assesses the main economic factors for the profitability of integrated plants and confirms
the importance of detailed operational and economic analyses for the assessment of the
potential of the integration options.
Kokoelmat
- Väitöskirjat [1036]