| 1. |
- Liu, Hao, et al.
(författare)
-
A thermodynamic study of hot syngas impurities in steel reheating furnaces : Corrosion and interaction with oxide scales
- 2014
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 77, s. 352-361
-
Tidskriftsartikel (refereegranskat)abstract
- Environmental concerns lead industries to implement gasified biomass (syngas) as a promising fuel in steel reheating furnaces. The impurities of syngas as well as a combination with iron oxide scale form complex mixtures with low melting points, and might cause corrosion on steel slabs. In this paper, the effects of syngas impurities are thermodynamically investigated, when scale formation on the steel slabs surface simultaneously takes place. A steel reheating furnace can be divided into preheating, heating, and soaking zones where the temperature of a steel slab changes respectively. Therefore, the thermodynamic calculation is performed at different temperatures to predict the fate of impurities. Then, the stable species are connected with respective zones in a reheating furnace. It is concluded that reactions due to alkali compounds, chloride, and particulate matter could take place on steel slabs. In the low temperature range, interaction of sodium chloride occured with pure iron prior to scale formation. Then, at high temperature the reactions of impurities are notable with iron oxides due to scale growing. Furthermore, the multicomponent reactions with syngas impurities showed that most of alkali contents evaporate at first stages, and only small amounts of them remain in slag at high temperature.
|
|
| 2. |
- Mellin, Pelle, 1985-, et al.
(författare)
-
Accuracy and Potential Use of a Developed CFD-pyrolysis Model for Simulating Lab-scale Bio Oil Production
- 2012
-
Ingår i: The 20th EU BC&E Online Proceedings 2012. - 9788889407547 ; , s. 953-959
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper describes development of a CFD¬pyrolysis model using an Eularian-Eularian framework with an implemented pyrolysis reaction model. The CFD¬pyrolysis model is used to simulate the bubbling fluidized bed reactor integrated in a new experimental fast pyrolysis process for bio oil production. The model is compared to experiments in aspect of outlet gas composition, temperature and bed height. Tar behavior and yield of bio oil are illustrated and a parametric study investigates impact of flow rate and temperature on bio oil yield. The results show a tolerable fit compared to measurements and reasonable tendencies in the parametric study.
|
|
| 3. |
- Mellin, Pelle, et al.
(författare)
-
An Euler–Euler approach to modeling biomass fast pyrolysis in fluidized-bed reactors – Focusing on the gas phase
- 2013
-
Ingår i: Applied Thermal Engineering. - : Elsevier BV. - 1359-4311 .- 1873-5606. ; 58:1-2, s. 344-353
-
Tidskriftsartikel (refereegranskat)abstract
- A developed 3D Euler–Euler CFD model, with an integrated pyrolysis model, is proposed as a way of predicting vapor phase dynamics and product distributions in the fluidized bed process for biomass fast pyrolysis. The main interest in this work is the gases resulting from the pyrolysis mixed with the fluidizing gas. We propose therefore a simple rendering of the solid material while directing attention to the vapor phase. At the same time the required computational resources for reaching stabilized conditions in the reactor are reduced. Temperature profile, velocity profile and pyrolysis products are predicted and globally verified by a series of parallel cases, which are compared to experimental measurements and known trends of liquid, solid and gas yields. The comparison of experimental measurements and model predictions satisfy the accuracy of the model and on a quantitative basis, the product yields agree with commonly known trends of bio oil versus temperature and residence time.
|
|
| 4. |
- Mellin, Pelle, et al.
(författare)
-
Biomass availability in Sweden for use in blast furnaces : International Conference on Applied Energy, ICAE2014
- 2014
-
Ingår i: Energy Procedia. - : Elsevier. ; , s. 1352-1355
-
Konferensbidrag (refereegranskat)abstract
- Based on the type of BF operated in Sweden, the pulverized coal (PC) has primarily been considered replaceable. If replacing the PC, a reduction of 1.25 Mton CO2 annually is possible, which would require approximately 4 TWh charcoal (0.46 Mton) or 7.14 TWh of dry raw biomass. This amount of biomass is substantial and availability is the main concern discussed in this paper. Uncertainty of the future biomass supply makes predictions beyond 2030 difficult. However, the predictions used in this work indicate that there is an unused potential, which could cover the need of all PCI in Sweden. Other aspects could potentially limit the proportion of PCI replaced by biomass, which should be further investigated.
|
|
| 5. |
- Mellin, Pelle, et al.
(författare)
-
Biomass availability in Sweden for use in blast furnaces
- 2014
-
Ingår i: Energy Procedia. - : Elsevier Ltd. ; , s. 1352-1355
-
Konferensbidrag (refereegranskat)abstract
- Based on the type of BF operated in Sweden, the pulverized coal (PC) has primarily been considered replaceable. If replacing the PC, a reduction of 1.25 Mton CO2 annually is possible, which would require approximately 4 TWh charcoal (0.46 Mton) or 7.14 TWh of dry raw biomass. This amount of biomass is substantial and availability is the main concern discussed in this paper. Uncertainty of the future biomass supply makes predictions beyond 2030 difficult. However, the predictions used in this work indicate that there is an unused potential, which could cover the need of all PCI in Sweden. Other aspects could potentially limit the proportion of PCI replaced by biomass, which should be further investigated.
|
|
| 6. |
|
|
| 7. |
- Mellin, Pelle, 1985-, et al.
(författare)
-
CFD Modelling of Heat Supply in Fluidized Bed Fast Pyrolysis of Biomass
- 2014
-
Ingår i: Proceedings of the 10th International Conference on Computational Fluid Dynamics in the Oil & Gas, Metallurgical and Process Industries (CFD 2014). - 9788214057416
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper investigates the heat supply to the fast pyrolysis process, by addition of oxygen in the fluidizing gas. Since the technology will be further developed, a solution for the heat supply in a large-scale reactor must be conceived, which is one option to achieve the primary target: to operate with as little extra heat as possible.Corrections for the granular bed material and the biomass particles are implemented in the simulation. User Defined Functions (UDF) is extensively used to describe interactions of heat and momentum between the phases and a chemistry model is employed to describe the chemical reactions after pyrolysis.The results are preliminary; however, the oxygen clearly reacts to provide heat. Primarily the secondary tar reacts and a loss of about 30% organic liquid yield is the result in this simulation, at an equivalence ratio of 0.026.If heat only can be recovered from the bed zone, through the bed material, then a higher equivalence ratio than what was investigated in this paper would be needed.If heat can be recovered from the whole reactor then a slight injection of oxygen would result in an autothermal system; which means the necessary heat to generate and pre-heat steam would be available.Temperature instability in the freeboard prevented investigation of higher equivalence ratios, which should be pursued in further work.
|
|
| 8. |
- Mellin, Pelle, 1985-, et al.
(författare)
-
Computational fluid dynamics modeling of biomass fast pyrolysis in a fluidized bed reactor, using a comprehensive chemistry scheme
- 2014
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 117:Part A, s. 704-715
-
Tidskriftsartikel (refereegranskat)abstract
- The CFD modeling for fast pyrolysis has previously focused on the major pyrolysis products; liquid, charand gas. This paper introduces a new approach to biomass pyrolysis; integrating a complex scheme of reactions including formation of such components as levoglucosan. The 3-D simulation takes into account the complex breakdown of each biomass subcomponent, the fluid dynamics of the process as well as the heat and momentum transfer of three Eulerian phases.The pyrolysis products include reference species that reflects the composition of the bio oil, gas fraction and char fraction. A number of reactions are in addition applied to account for the thermal cracking of tar compounds and the final compositions are compared to experimental yields. The results show that the predicted pyrolysis products reflect the experimental yields satisfactorily, apart from the water content which is under predicted. Most importantly though, the approach is computationally feasible and it should be useful for future work.
|
|
| 9. |
- Mellin, Pelle, 1985-, et al.
(författare)
-
Processing of biomass to Hydrocarbons – using a new catalytic steam pyrolysis route
- 2014
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Obtaining renewable transportation fuel has been identified as one of the main challenges for a sustainable society. Catalytic pyrolysis followed by hydrotreatment has been demonstrated as one possible route for producing transportation fuels. Using steam in this process could have a number of benefits as given by our research effort. For this paper, we will show that a catalyst together with steam prolongs the activity of the catalyst by preventing coking. This means that both steam and catalyst mutually benefits the deoxygenation. The presented mass and energy balance shows that up to 40% of the calorific value of biomass remains in the deoxygenated oil, on dry basis. This is in contrast to the mass yield, which for the same case was 25%; meaning that the oil is of significantly higher quality with a high content of hydrocarbons. In addition, CFD studies have shown steam is able to redistribute the heat flux and provide more uniform operating conditions compared to for example nitrogen. In conclusion, this route using steam shows promise for displacing fossil transportation fuels, by upgrading of the liquid in existing refineries or next-generation bio refineries. In additional support of this, we have published a number of papers describing conventional fast pyrolysis using steam, CFD modeling for further understanding and experimental work using a combination of steam and firstly a bimetallic catalyst (Ni, V) then a metal modified HZSM5 catalyst (Ni, V, Zeolite, Binder). This paper connects all these individual studies and provides further understanding of the role of steam and the role of steam in combination with a catalyst, in the fast pyrolysis process.
|
|
| 10. |
- Mellin, Pelle, et al.
(författare)
-
Simulation of Bed Dynamics and Primary Products from Fast Pyrolysis of Biomass : Steam Compared to Nitrogen as a Fluidizing Agent
- 2014
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:30, s. 12129-12142
-
Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis of biomass, using steam as a fluidizing agent, provides several benefits. In this paper, an unsteady multiphase computational fluid dynamics (CFD) model coupled with a comprehensive kinetic scheme for primary pyrolysis is used to obtain the formation rates of primary products and compare the profiles when operating with steam and nitrogen. The model only considers the physical effects of the fluidizing gas at the moment, although a literature review indicates the existence of various chemical and surface-interacting effects. At stabilized pyrolysis reaction rates, the product yields were compared to data found in the literature, which indicated similar yields; this supports the correct implementation of the kinetic model. However, the difference in overall rate and composition is very small when steam is compared to nitrogen. The simultaneous simulation of bed dynamics indicate a shifted formation rate of primary products toward the lower part of the fluidized bed, with an increase in solid vapor contact time and better temperature distribution as a result. More specifically, total heat flux to the biomass increased by 1396 in the lowest part of the reactor. In addition, more heat from the sand is carried through the gas phase when using steam: an increase by 9% in the overall reactor (25% in the lowest part), as indicated by the results. Finally, since no substantial differences in overall product formation rate and composition were found, the considerable effect of steam found in experiments and the literature is mainly (not exclusively) attributed to the chemical and surface-interacting mechanisms. Because of the complex nature of secondary pyrolysis in this process, a comprehensive gas-phase kinetic model is needed to investigate the effects of steam further. Coupling of both is difficult, because of computational constraints, as the present model already is very demanding. The obtained profiles of formation rate of primary products can however be used as an input to another model specifically made for studying homogeneous secondary pyrolysis reactions.
|
|
