| 1. |
- Grimm, Alejandro, et al.
(författare)
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Slagging and fouling characteristics during co-combustion of Scots pine bark with low-temperature dried pulp and paper mill chemical sludge
- 2019
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 193, s. 282-294
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Tidskriftsartikel (refereegranskat)abstract
- This paper shows how chemical sludge (CS) generated during wastewater treatment at a paperboard mill can be quickly dried at low-temperature and employed in bark-fired boilers to reduce slagging and corrosion problems. By using a cyclone-dryer operated at an inlet-air velocity of 110 m/s and a temperature of 90 degrees C, the dry-matter content of CS was increased from approximately 19 to 82%. The residence time of CS inside the cyclone was approximately 2 s when using the inlet-air velocity mentioned above. Disaggregation of the feedstock caused by collisions with the cyclone wall and between particles played a crucial role in enhancing the efficiency of heat and mass transfer. Three co-pelletized mixtures of Scots pine bark (SPB) and dried-CS were combusted in a 40 kW fixed-bed burner. Flue gas analysis was performed with a gas analyser. Coarse and fine ash were analysed by SEM-EDS and XRD. NOx, and SO2 emissions increased with increasing amount of CS in the mixtures. Mono combustion of SPB resulted in a large quantity of slag (i.e., molten ash) with a high degree of sintering (i.e., hardness of the slag), and ash deposits formed on heat transfer surfaces were rich in K2SO4 and KCI. Mixtures of SPB and CS were less prone to slagging, and the amount of alkali chloride in the deposits was reduced in favour of alkali sulphate formation.
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| 2. |
- He, Jie
(författare)
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Gasification-based Biorefinery for Mechanical Pulp Mills
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The modern concept of “biorefinery” is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various bio-based products. It includes thermochemical processes such as gasification and fast pyrolysis. In thermo-mechanical pulp (TMP) mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, bio-sludges and other available fuels such as peat, recycled wood and paper products. On the other hand, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. The huge amount of purchased electricity can be compensated for by self-production of electricity from gasification, or the involved cost can be compensated for by extra revenue from bio-transport fuel production. This work is to study co-production of bio-automotive fuels, bio-power, and steam via gasification of the waste biomass streams in the context of the mechanical pulp industry. Ethanol and substitute natural gas (SNG) are chosen to be the bio-transport fuels in the study. The production processes of biomass-to-ethanol, SNG, together with heat and power, are simulated with Aspen Plus. Based on the model, the techno-economic analysis is made to evaluate the profitability of bio-transport fuel production when the process is integrated into a TMP mill.The mathematical modelling starts from biomass gasification. Dual fluidized bed gasifier (DFBG) is chosen for syngas production. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150KWth Mid Sweden University (MIUN) DFBG. As a reasonable result, the tar content in the syngas decreases with the gasification temperature and the steam to biomass (S/B) ratio. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass or product gas needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming.For ethanol production, a stand-alone thermo-chemical process is designed and simulated. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost. The calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built over 200 MW.In TMP mills, wood and biomass residues are commonly utilized for electricity and steam production through an associated CHP plant. This CHP plant is here designed to be replaced by a biomass-integrated gasification combined cycle (BIGCC) plant or a biomass-to-SNG (BtSNG) plant including an associated heat & power centre. Implementing BIGCC/BtSNG in a mechanical pulp production line might improve the profitability of a TMP mill and also help to commercialize the BIGCC/BtSNG technologies by taking into account of some key issues such as, biomass availability, heat utilization etc.. In this work, the mathematical models of TMP+BIGCC and TMP+BtSNG are respectively built up to study three cases: 1) scaling of the TMP+BtSNG mill (or adding more forest biomass logging residues in the gasifier for TMP+BIGCC); 2) adding the reject fibres in the gasifier; 3) decreasing the TMP SEC by up to 50%.The profitability from the TMP+BtSNG mill is analyzed in comparison with the TMP+BIGCC mill. As a major conclusion, the scale of the TMP+BIGCC/BtSNG mill, the prices of electricity and SNG are three strong factors for the implementation of BIGCC/BtSNG in a TMP mill. A BtSNG plant associated to a TMP mill should be built in a scale above 100 MW in biomass thermal input. Comparing to the case of TMP+BIGCC, the NR and IRR of TMP+BtSNG are much lower. Political instruments to support commercialization of bio-transport fuel are necessary.
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| 3. |
- Khani, Sajjad, et al.
(författare)
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Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function
- 2024
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Ingår i: Nature Metabolism. - 2522-5812.
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Tidskriftsartikel (refereegranskat)abstract
- Promoting brown adipose tissue (BAT) activity innovatively targets obesity and metabolic disease. While thermogenic activation of BAT is well understood, the rheostatic regulation of BAT to avoid excessive energy dissipation remains ill-defined. Here, we demonstrate that adenylyl cyclase 3 (AC3) is key for BAT function. We identified a cold-inducible promoter that generates a 5′ truncated AC3 mRNA isoform (Adcy3-at), whose expression is driven by a cold-induced, truncated isoform of PPARGC1A (PPARGC1A-AT). Male mice lacking Adcy3-at display increased energy expenditure and are resistant to obesity and ensuing metabolic imbalances. Mouse and human AC3-AT are retained in the endoplasmic reticulum, unable to translocate to the plasma membrane and lack enzymatic activity. AC3-AT interacts with AC3 and sequesters it in the endoplasmic reticulum, reducing the pool of adenylyl cyclases available for G-protein-mediated cAMP synthesis. Thus, AC3-AT acts as a cold-induced rheostat in BAT, limiting adverse consequences of cAMP activity during chronic BAT activation.
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| 4. |
- Moser, Konstantin, et al.
(författare)
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Screw reactors and rotary kilns in biochar production – A comparative review
- 2023
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier. - 0165-2370 .- 1873-250X. ; 174:September 2023
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Tidskriftsartikel (refereegranskat)abstract
- One promising technology in the field of residue valorization is the pyrolytic conversion of biomass to biochar. There are a lot of proven technologies for this task, with many of them being quite distinctive. Biochar has a lot of valuable properties and it shows potential to be applicated in many different fields of industry as a green carbon resource. Thus, as the demand for its production rises, more and more people from different fields share interest in the same technologies and the demand for guidance in form of readily available information increases. Two prominent technologies rather similar in appearance are rotary kilns and screw reactors. Both technologies consist of a long, hollow cylinder and both technologies use some form of longitudinal rotation as a means to transport feedstock. In this review, both technologies are described and their biggest differences and similarities are discussed, all under the aspect of biochar production. In total, 21 unique rotary kilns and 58 unique auger reactors were identified. The paper addresses process specific aspects, like heat supply or residence time, but it also gives an overview on current research and general aspects like scale-up considerations. Differences between both technologies were found in all of these aspects, with some of the most pronounced being the bigger maximum capacities and the greater residence time distributions in rotary kiln pyrolysis. Both technologies are viable candidates for producing biochar on a commercial level, however, literature comparing the influence of the reactor type on biochar properties was very scarce. As a future outlook it is recommended to produce data that can be compared on a quantitative level, so a more accurate assessment of each technologies up- and downsides can be made.
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| 5. |
- Pfeifer, Kathrin, et al.
(författare)
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Identification and characterization of a twist ortholog in the polychaete annelid Platynereis dumerilii reveals mesodermal expression of Pdu-twist
- 2013
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Ingår i: Development, Genes and Evolution. - : Springer Berlin/Heidelberg. - 0949-944X .- 1432-041X. ; 223:5, s. 319-328
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Tidskriftsartikel (refereegranskat)abstract
- The basic helix-loop-helix transcription factor twist plays a key role during mesoderm development in Bilateria. In this study, we identified a twist ortholog in the polychaete annelid Platynereis dumerilii and analyze its expression during larval development, postlarval growth up to the adult stage, and caudal regeneration after amputation of posterior segments. At late larval stages, Pdu-twist is expressed in the mesodermal anlagen and in developing muscles. During adulthood and caudal regeneration, Pdu-twist is expressed in the posterior growth zone, in mesodermal cells within the newly forming segments and budding parapodia. Our results indicate that Pdu-twist is involved in mesoderm formation during larval development, posterior growth, and caudal regeneration.
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| 6. |
- Ueda, Kiyoshi, et al.
(författare)
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Roadmap on photonic, electronic and atomic collision physics : I. Light-matter interaction
- 2019
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Ingår i: Journal of Physics B. - : IOP PUBLISHING LTD. - 0953-4075 .- 1361-6455. ; 52:17
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Tidskriftsartikel (refereegranskat)abstract
- We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light-matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field.
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