| 1. |
- Bonmann, Marlene, 1988, et al.
(författare)
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Sub-millimetre wave range-Doppler radar as a diagnostic tool for gas-solids systems - solids concentration measurements
- 2023
-
Ingår i: Advanced Powder Technology. - : Elsevier BV. - 0921-8831 .- 1568-5527. ; 34:1
-
Tidskriftsartikel (refereegranskat)abstract
- Current non-intrusive measurement techniques for characterising the solids flow in gas-solids suspensions are limited by the low temporal or low spatial resolution of the sample volume, or in the case of optical methods, by a short range of sight. In this work, a sub-millimetre wave range-Doppler radar is developed and validated for non-intrusive sensing of solids concentrations in a gas-solids particle system with known characteristics. The radar system combines favourable features, such as the ability to see through at optical frequencies opaque materials, to measure the local solids velocity and the reflected radar power with a spatial resolution of a few cubic centimetres over distances of a few metres. In addition, the radar hardware offers flexibility in terms of installation. After signal processing, the output of the radar is range-velocity images of the solids flowing along the radar’s line-of-sight. The image frame rate can be close to real-time, allowing the solids flow dynamics to be observed. While the well-established Doppler principle is used to measure the solids velocity, this paper introduces a method to relate the received radar signal power to the solids volumetric concentrations (cv) of different particulate materials. The experimental set-up provides a steady stream of free-falling solids that consist of glass spheres, bronze spheres or natural sand grains with known particle size distributions and with particle diameters in the range of 50–300 µm. Thus, the values of cv found using the radar measurements are validated using the values of cv retrieved from closure of the mass balance derived from the measured mass flow rate of the solids stream and the solids velocity. The results show that the radar system provides reliable measurements of cv, with a mean relative error of approximately 25 % for all the tested materials, particle sizes and mass flow rates, yielding values of cv ranging from 0.2 × 10-4 m3/m3 up to 40 × 10-4 m3/m3 and solids velocities within the range of 0–4.5 m/s. This demonstrates the ability of the radar technology to diagnose the solids flow in gas-solids suspensions using a unique combination of penetration length, accuracy, and spatial and time resolution. In future work, the radar technique will be applied to study non-controlled solids flow at a larger scale, and to understand flow conditions relevant to industrial reactor applications, e.g., fluidised bed, entrained flow, and cyclone units.
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| 2. |
- Guio Perez, Diana Carolina, 1985, et al.
(författare)
-
Radar-based measurements of the solids flow in a circulating fluidized bed
- 2023
-
Ingår i: Fuel. - 0016-2361. ; 345
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this work is to demonstrate the value of radar technology for studying experimentally the solids flows in gas-solids fluidized beds. The work presents original results regarding the solids concentration and velocity acquired in a non-intrusive manner from a cold flow model. The tailored radar setup operates at submillimeter wave frequencies (0.34 THz) and can measure the location of solids with a spatial resolution of 1/8 mm−1 in the direction of the radar beam, and of 40–60 mm across the radar beam. The solids velocity in the direction of the beam propagation is determined through measurement of the Doppler shift caused by the reflection of the transmitted radar signal by solids moving in relation to the antenna. The measurements were performed in both the horizontal and vertical directions in the riser of a circulating fluidized bed (cross-sectional area of 0.45 m2 and height of 3.1 m) operated with glass beads (mean particle size of 106 µm, and particle density of 2,486 kg/m3) and using air at ambient temperature as the fluidization agent, with superficial velocities in the range of 0.3–1.3 m/s. The measurements are used to assess the validity of the technique and are not intended to characterize the unit fluid dynamically. The solids concentrations derived from the radar measurements follow the qualitative trends derived from pressure-drop measurements, resembling the expected changes that occur in the concentration profiles as the fluidization velocity increases. Concentrations in the range from 10-6 m3/m3 to 10-1 m3/m3 are measurable. In quantitative terms, for low concentrations of solids (<5·10-3 m3/m3, approximately) the radar measurements exhibited the ability to provide more consistent measurements of the solids concentration than those obtained from pressure transducers, for which the small pressure differences lead to unstable and even negative values for solids concentrations. The two measurement methods were in quantitative agreement for solids volume fractions higher than the threshold. Concentrations ≥ 1·10-1 m3/m3, though measurable, strongly attenuate the radar signal, thereby reducing the beam penetration to a depth of centimeters. For each position along the radar beam, the distribution of solids velocity measured from the Doppler effect was found to be within the expected ranges and allowed observations of solids back-mixing. The radar technique applied in this work is a promising technique for detailed characterization of the solids flow in fluidized beds, offering high spatial and temporal resolutions, allowing the determination of both solids velocity and concentration, and having a reasonably high penetration depth.
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| 3. |
- Larsson, Anton, 1984, et al.
(författare)
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Zero-dimensional modeling of indirect fluidized bed gasification
- 2010
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Ingår i: 13th International Conference on Fluidization.
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Konferensbidrag (refereegranskat)abstract
- Zero-dimensional models has been developed to investigate mass balance and fuel (biomass) conversion in Chalmers 2-4 MWfuel indirect fluidized bed gasifier. The input to the model is measured concentrations and flows. The model shows that the conversion factor of the water gas shift reaction is around 40 %.
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| 4. |
- Thunman, Henrik, 1970, et al.
(författare)
-
Advanced biofuel production via gasification – lessons learned from 200 man-years of research activity with Chalmers’ research gasifier and the GoBiGas demonstration plant.
- 2018
-
Ingår i: Energy Science and Engineering. - : Wiley. - 2050-0505. ; 6:1, s. 6-34
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the main experiences gained and conclusions drawn from the demonstration of a first-of-its-kind wood-based biomethane production plant (20-MW capacity, 150 dry tonnes of biomass/day) and 10 years of operation of the 2–4-MW (10–20 dry tonnes of biomass/day) research gasifier at Chalmers University of Technology in Sweden. Based on the experience gained, an elaborated outline for commercialization of the technology for a wide spectrum of applications and end products is defined. The main findings are related to the use of biomass ash constituents as a catalyst for the process and the application of coated heat exchangers, such that regular fluidized bed boilers can be retrofitted to become biomass gasifiers. Among the recirculation of the ash streams within the process, presence of the alkali salt in the system is identified as highly important for control of the tar species. Combined with new insights on fuel feeding and reactor design, these two major findings form the basis for a comprehensive process layout that can support a gradual transformation of existing boilers in district heating networks and in pulp, paper and saw mills, and it facilitates the exploitation of existing oil refineries and petrochemical plants for large-scale production of renewable fuels, chemicals, and materials from biomass and wastes. The potential for electrification of those process layouts are also discussed. The commercialization route represents an example of how biomass conversion develops and integrates with existing industrial and energy infrastructures to form highly effective systems that deliver a wide range of end products. Illustrating the potential, the existing fluidized bed boilers in Sweden alone represent a jet fuel production capacity that corresponds to 10% of current global consumption.
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| 5. |
- Alamia, Alberto, 1984, et al.
(författare)
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Process Simulation of Dual Fluidized Bed Gasifiers Using Experimental Data
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:5, s. 4017-4033
-
Tidskriftsartikel (refereegranskat)abstract
- Process simulation of a dual fluidized bed (DFB) gasifier is challenging, owing to the high degree of freedominherent to the operation of the double-reactor system and the complexity of the reactions therein. We propose a method forsimulation of the gasifier based on the analysis of experimental data and of the total uncertainty associated with them. The overallaim is to use data from the large amount of pilot and demonstration gasifiers in the analysis and optimization of gasification-basedprocesses. In the method proposed a set of fuel conversion variables and their associated uncertainties are calculated using astochastic approach that takes into account the effect of unclosed mass balance, incomplete characterization of the raw gascompounds and measurement errors. Subsequently, these fuel conversion variables are used to simulate the gasifier in a flowsheetmodel developed in Aspen Plus. The results include the evaluation of critical parameters, such as, gasifier efficiency, chargasification, and tar yield and their uncertainties, which depend highly on the measurement system. The method is applied todata sets derived from several measurement setups, and the results are validated with total carbon measurements. The resultsshow that detection of ≥95% of the carbon in the raw gas is necessary to maintain the uncertainty level at
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| 6. |
- Berdugo Vilches, Teresa, 1985, et al.
(författare)
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Bed material as a catalyst for char gasification: The case of ash-coated olivine activated by K and S addition
- 2018
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 224, s. 85-93
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, the ability of an ash-coated olivine to catalyze the steam gasification of biomass-derived char is investigated in a laboratory reactor. The olivine investigated is a sample from the Chalmers dual fluidized bed gasifier and it has been activated by the in-bed addition of S and K 2 CO 3 . The char and bed material samples were analyzed by Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS). It is shown that the ash layer coating of the olivine can catalyze the steam gasification of char by transferring catalytic potassium (K) to the char particles. The mobilities of the catalytic species from the olivine ash-layer are discussed. This work furthers the current understanding of the catalytic activities of ash-coated bed material particles during the thermochemical conversion of carbonaceous feedstocks in fluidized beds. In addition, it complements the existing literature on catalytic bed materials, which to date have focused on tar removal and improving gas quality.
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| 7. |
- Berdugo Vilches, Teresa, 1985, et al.
(författare)
-
Comparing Active Bed Materials in a Dual Fluidized Bed Biomass Gasifier: Olivine, Bauxite, Quartz-Sand, and Ilmenite
- 2016
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:6, s. 4848-4857
-
Tidskriftsartikel (refereegranskat)abstract
- Active bed materials are in this work investigated for in situ gas upgrading of biomass-derived gas. Previous research on in situ gas upgrading has focused on assessing gas quality, in terms of the concentrations of tar and permanent gases. Other aspects of fuel conversion, such as char conversion and the impact of oxygen transport on the final gas, are not as well documented in the literature on gasification. In this paper, the overall biomass conversion in a dual fluidized bed biomass gasifier is investigated in the presence of the catalytic material olivine and the alkali-binding material bauxite. The impact of these materials on fuel conversion is described as the combination of four effects, which are induced by the bed material: thermal, catalytic, ash-enhanced catalytic effect, and oxygen transport. Quartz-sand and ilmenite are here used as the reference materials for the thermal and the oxygen transport effects, respectively. Olivine and bauxite show activity toward tar species compared to quartz-sand. After 1 week of operation and exposure to biomass ash, the activities of olivine and bauxite toward tar species increase further, and the water gas shift reaction is catalyzed by both materials. Additionally, bauxite shows a stronger ability to increase char conversion than olivine. Under the conditions tested, olivine and bauxite have some degree of oxygen transport capacity, which is between those of quartz-sand and ilmenite. The oxygen transport effect is higher for bauxite than for olivine; nevertheless, the catalytic activities of the materials result in higher yields of H-2 than in a similar case with quartz-sand. The implications of the findings for the operation of dual fluidized bed gasifiers are discussed.
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| 8. |
- Berdugo Vilches, Teresa, 1985, et al.
(författare)
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Influence of in-bed catalysis by ash-coated olivine on tar formation in steam gasification of biomass
- 2018
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 32:9, s. 9592-9604
-
Tidskriftsartikel (refereegranskat)abstract
- The use of catalytic bed materials has become a state-of-the-art solution to control the concentration of tar in fluidized bed biomass steam gasifiers. Ash-coated olivine is commonly applied as bed material, owing to its relatively high catalytic activity towards tar species. However, the mechanisms and conversion pathways influenced by the ash-coated olivine when applied as an in-bed catalyst are still not well understood. The present work aims at proving that the ash-layered olivine prevents the formation of biomass-derived tar at an early stage of their formation. Tests with olivine at different stages of activation and at different temperatures are carried out in the Chalmers 2-4MWth DFB gasifier. Detailed characterization of the tar and light hydrocarbon fractions are presented and discussed in relation to the sources of aromatic species. It is concluded that the ash-coated olivine prevents the formation of aromatic tar species by promoting the steam reforming of early tar precursors. Gas-phase interactions of the early tar precursors and bed material contribute to the tar reduction observed. The results indicate that olivine interferes the cyclization routes involving C2H2 and C3 hydrocarbons.
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| 9. |
- Berdugo Vilches, Teresa, 1985, et al.
(författare)
-
Mapping the effects of potassium on fuel conversion in industrial-scale fluidized bed gasifiers and combustors
- 2021
-
Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 11:11
-
Tidskriftsartikel (refereegranskat)abstract
- Potassium (K) is a notorious villain among the ash components found in the biomass, being the cause of bed agglomeration and contributing to fouling and corrosion. At the same time, K is known to have catalytic properties towards fuel conversion in combustion and gasification environments. Olivine (MgFe silicate) used as gasifier bed material has a higher propensity to form catalytically active K species than traditional silica sand beds, which tend to react with K to form stable and inactive silicates. In a dual fluidized bed (DFB) gasifier, many of those catalytic effects are expected to be relevant, given that the bed material becomes naturally enriched with ash elements from the fuel. However, a comprehensive overview of how enrichment of the bed with alkali affects fuel conversion in both parts of the DFB system is lacking. In this work, the effects of ash-enriched olivine on fuel conversion in the gasification and combustion parts of the process are mapped. The work is based on a dedicated experimental campaign in a Chalmers DFB gasifier, wherein enrichment of the bed material with K is promoted by the addition of a reaction partner, i.e., sulfur, which ensures K retention in the bed in forms other than inactive silicates. The choice of sulfur is based on its affinity for K under combustion conditions. The addition of sulfur proved to be an efficient strategy for capturing catalytic K in olivine particles. In the gasification part, K-loaded olivine enhanced the char gasification rate, decreased the tar concentration, and promoted the WGS equilibrium. In the combustion part, K prevented full oxidation of CO, which could be mitigated by the addition of sulfur to the cyclone outlet.
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| 10. |
- Berdugo Vilches, Teresa, 1985, et al.
(författare)
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Shedding light on the governing mechanisms for insufficient CO and H2 burnout in the presence of potassium, chlorine and sulfur
- 2020
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 273
-
Tidskriftsartikel (refereegranskat)abstract
- Based on the experiences of insufficient burnout in industrial fluidized bed furnaces despite adequate mixing and availability of oxidizer, the influence of potassium on CO and H2 oxidation in combustion environments was investigated. The combustion environments were provided by a laminar flame burner in a range relevant to industrial furnaces, i.e. 845 °C to 1275 °C and excess air ratios ranging from 1.05 to 1.65. Potassium, in the form of KOH, was homogeneously introduced into the hot gas environments to investigate its effect on the radical pool. To quantitatively determine key species that are involved in the oxidation mechanism (CO, H2, KOH, OH radicals, K atoms), a combination of measurement systems was applied: micro-gas chromatography, broadband UV absorption spectroscopy and tunable diode laser absorption spectroscopy. The inhibition effect of potassium on CO and H2 oxidation in excess air was experimentally confirmed and attributed to the chain-terminating reaction between KOH, K atoms and OH radicals, which enhanced the OH radical consumption. The addition of chlorine or sulfur could reduce the concentrations of KOH and K atoms and consequently eliminated the inhibition on CO and H2 oxidation. Existing kinetic mechanisms underestimate the inhibiting effect of potassium and they fail to predict the effect of temperature on CO and H2 concentration when potassium and sulfur co-exist. This work advances the need to revise existing kinetic mechanisms to fully capture the interplay of K and S in the oxidation of CO and H2 in industrial fluidized bed furnaces.
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| 11. |
- Berguerand, Nicolas, 1978, et al.
(författare)
-
Producer Gas Cleaning in a Dual Fluidized Bed - a Comparative Study of Performance with Ilmenite and a Manganese Oxide as Catalysts
- 2012
-
Ingår i: Biomass Conversion and Biorefinery. - : Springer Science and Business Media LLC. - 2190-6815 .- 2190-6823. ; 2:3, s. 8-252
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Tidskriftsartikel (refereegranskat)abstract
- Secondary catalytic gas conditioning is one strategy to eliminate tars formed in a producer gas during biomass gasification. However, most catalysts tend to lose their tar reforming activity after short period of operation due to carbon formation. A novel technique for catalytic gas cleaning based on two interconnected fluidized beds has been investigated; this technique can be applied to all types of gasifiers. The idea is to reform the tar components into useful molecules - even at high tar contents - by means of a circulating catalyst. More precisely, the producer gas is cleaned with catalyst in one of the reactors, referred to as the fuel reactor (FR), while the catalyst is continuously regenerated in another reactor, the air reactor (AR). The system described here is coupled with the Chalmers 2-4 MWth biomass gasifier while the AR is fed with nitrogen-diluted air. The effect of different catalysts on both the tar content and the gas composition was investigated. Some of the tested materials do not only reform tars, they also influence the H2/CO-ratio in a beneficial manner; in particular, ratios closer to 3 in the reformed gas are favorable if subsequent methanation is implemented. In this paper, comparative results based on testing with manganese- and iron-based catalysts are presented. The former is a manufactured catalyst while the latter is a natural ore. Results suggest that both show satisfying ability for regeneration from carbon deposits. Higher temperature enhances tar decomposition during experiment with both catalysts. Moreover, the iron-based catalyst enhances water gas shift activity, which in turns impacts the total amount of produced gas. On the other hand, the manganese-based catalyst seems to display higher propensity for tar conversion.
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| 12. |
- Berguerand, Nicolas, 1978, et al.
(författare)
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Producer Gas Cleaning in a Dual Fluidized Bed Reformer using Two Catalysts
- 2011
-
Ingår i: Compendium of the International Conference on Polygeneration Strategies11. ; , s. 9-
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Konferensbidrag (refereegranskat)abstract
- The most elegant method to remove tars out of producer gas from biomass gasification is catalytic hot gas cleaning. However, most catalysts are poisoned after short operation due to carbon formation or by other contaminants on their active sites. A novel technique for catalytic gas cleaning based on two interconnected fluidized beds has been investigated. The idea is to reform the tar components into useful molecules by means of a circulating catalyst, also called oxygen carrier in the following. The producer gas is cleaned in one of the reactors, referred to as the fuel reactor (FR), while it is continuously regenerated in the air reactor (AR). The two reactors are separated by loop seals in such a way that gas leakage is prevented between the reactors while solid circulation occurs. By varying the circulation rate of material in the system, the residence time in the raw gas stream and the frequency of regeneration can be adjusted. Meanwhile, the required amount of oxygen for partial oxidation of the tars is transferred. The system described here is coupled with its FR to the Chalmers 2-4 MWth biomass gasifier while the AR is fed with nitrogen-diluted air. In preliminary tests, the effect of different catalysts on both the tar content and the gas composition was investigated. Some of the tested materials do not only reform tars, they also influence the H2/CO-ratio in a beneficial manner. In this paper, comparative results based on testing with manganese and iron based catalysts are presented. Results suggest that both show satisfying ability for regeneration from carbon deposits. Higher temperature enhances tar removal during experiment with both catalysts. Moreover, the iron-based catalyst enhances water gas shift activity, which in turns impacts the total amount of produced gas. On the other hand, the manganese-based catalyst seems to express higher propensity for tar conversion. These observations elicit an interesting flexibility of the process as a judicious set of catalyst in coordination with pertinent operating conditions can be chosen to achieve desired purposes.
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| 13. |
- Berguerand, Nicolas, 1978, et al.
(författare)
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Use of Nickel Oxide as a Catalyst for Tar Elimination in a Chemical-Looping Reforming Reactor Operated with Biomass Producer Gas
- 2012
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:51, s. 16610-16616
-
Tidskriftsartikel (refereegranskat)abstract
- A secondary tar-cleaning process based on Chemical-Looping Reforming (CLR) was investigated for upgrading biomass producer gas, derived from the Chalmers University of Technology 2-4 MW indirect gasifier. The experiments were conducted in a bench-scale CLR reactor using a manufactured nickel oxide (NiO) catalyst. Although Ni is a well-documented and efficient steam-reforming catalyst, it is susceptible to rapid deactivation under tar-rich conditions. The aim of this study was to explore the advantages of CLR as a gas-cleaning application, a process which offers continuous regeneration of the carbon deposits on catalysts. The tar-reforming performance of this Ni material and its influence on the gas composition and in particular its potential to increase the H2/CO ratio, were studied. The system was tested at reforming temperatures that ranged from 700°C to 880°C and at oxygen concentrations of 1.0% and 2.2% in the inlet feed to regenerator section. The results confirm the strong ability of the catalyst to reform tars. Higher process temperatures clearly promoted tar conversion, with 96% overall conversion at 880°C (99% if benzene is excluded), as compared with 45% conversion at 700°C. The hydrogen production was favored when temperature was raised. Though, a maximum ratio H2/CO of 2.2 was observed at 750°C. Finally, no time-on-stream deactivation of the catalyst in the CLR was observed during the test, which lasted almost 7 hours.
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| 14. |
- Bidgoli, Hosein, 1987, et al.
(författare)
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Terahertz Spectroscopy for Real-Time Monitoring of Water Vapor and CO Levels in the Producer Gas From an Industrial Biomass Gasifier
- 2014
-
Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 4:6, s. 722-733
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a study of THz transmission spectroscopy as a novel tool for the monitoring of the steam and CO contents of the raw gas from industrial biomass gasifiers. A THz gas spectrometer with a frequency range of 300–500 GHz was designed and constructed. Proof-of-principle testing was performed at laboratory conditions using mixtures of different gases at high temperatures (600–700 K). The results demonstrate the feasibility of applying strong rotational water vapor lines at 448 and 383 GHz, so as to obtain reliable online measurements of water vapor with an absolute precision of about 0.2 vol.% for the current device. CO lines were identified at 461 and 346 GHz, facilitating measurement of this gas. The gas spectrometer was integrated into an industrial gasifier and boiler, and its performance was tested in terms of online measurements of steam and CO in the hot raw gas and flue gases under real-life conditions. Considering the error intervals, the results are in complete agreement with data acquired by solving loose mass balances around the system. The onsite experiments demonstrate that THz gas spectroscopy is a promising tool for fast, robust, and reliable monitoring in industrial applications.
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| 15. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Feedstock recycling of cable plastic residue via steam cracking on an industrial-scale fluidized bed
- 2024
-
Ingår i: Fuel. - 0016-2361. ; 355
-
Tidskriftsartikel (refereegranskat)abstract
- The use of plastic materials in a circular way requires a technology that can treat any plastic waste and produce the same quality of product as the original. Cable plastic residue from metal recycling of electric wires is composed of cross-linked polyethene (XLPE) and PVC, which is a mixture that cannot be mechanically recycled today. Through thermochemical processes, polymer chains are broken into syngas and monomers, which can be further used in the chemical industry. However, feedstock recycling of such a mixture (XLPE, PVC) has been scarcely studied on an industrial scale. Here, the steam cracking of cable plastic was studied in an industrial fluidised bed, aiming to convert cable plastics into valuable products. Two process temperatures were tested: 730 °C and 800 °C. The results show that the products consist of 27–31 wt% ethylene and propylene, 5–16% wt.% other linear hydrocarbons, and more than 10 wt% benzene. Therefore, 40%–60% of the products are high-value chemicals that could be recovered via steam cracking of cable plastic.
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| 16. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Thermochemical recycling of tall oil pitch in a dual fluidized bed
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 340
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Tidskriftsartikel (refereegranskat)abstract
- Crude tall oil is a by-product obtained from the manufacture of chemical wood pulp. The residue obtained after the distillation of this product is known as tall oil pitch (TOP). This complex fraction is a highly viscous liquid that consists mainly of free fatty acids, fatty acids derivatives, rosin acids and additives. Given its complex composition, it is commonly used as fuel for heat production. In this work, steam cracking is proposed as an alternative treatment for this residue. Steam cracking can convert TOP into a valuable product gas that can be used in different applications including the production of green chemicals, moving towards a carbon circular economy. The experimental tests were performed in the Chalmers pilot scale Dual Fluidized Bed, consisting of a steam cracker and a combustor. For these experiments, the thermochemical decomposition of 150–175 kg/h TOP was performed at the steam cracker at two different temperatures (775 and 825 °C) to evaluate the influence of this parameter on the obtained products. Wood pellets were also tested as reference material for the highest temperature. The distribution of the obtained products was analysed. Results show that TOP can be regarded as a by-product instead of a residue and used as feedstock for the recovery of chemical building blocks and syngas via thermochemical recycling. Between 40 and 50 % of the carbon present in the fuel is kept in the permanent gases, while about 20 % is in aromatic hydrocarbons. Compared to biomass, the aromatics yield obtained for TOP is much higher (190 g/kg for TOP and 13 g/kg for biomass). Among the species found, benzene, toluene and xylene, represent between 62 and 72 % of the total measured aromatics. Regarding the gas fraction, the production of valuable light hydrocarbons (such as ethylene and propylene) is more pronounced in the TOP residue than in the biomass. In addition, an energy balance over the system was estimated and showed that TOP thermochemical recycling can be self-sustained in a Dual Fluidized Bed if the non-valuable products are combusted. The results obtained in this work indicate that this TOP could be an appealing option to consider as a source of biorefinery revenue leading to the circular use of waste.
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| 17. |
- Cañete Vela, Isabel, 1992, et al.
(författare)
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Valorisation of textile waste via steam gasification in a fluidized bed reactor
- 2019
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Ingår i: Proceedings - HERAKLION 2019 - 7th International Conference on Sustainable Solid Waste Management.
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Konferensbidrag (refereegranskat)abstract
- Demand for textile production is constantly increasing together with population expansion and economic development of the society. Reaching the end-of-life, textile products are becoming waste, which is nowadays mostly incinerated and landfilled. Pathways of fibre recycling are known for singlematerial garments i.e. cotton, despite this, several textile products contain a blend of both synthetic and natural fibres which are hard to sort and recycle. Those abounded textile waste fractions can, via feedstock recycling, be converted to high-value chemicals. The principle of the process is to brake polymer chains from the textile to its constituents, which are can be used as chemicals, replacing fossil fuels as feedstock. This paper analyses the potential of feedstock production from steam gasification of textile waste through experimental work in a fluidized bed bench-scale reactor. Additionally, the monomer recovery was studied for textiles with diverse chemical structure: natural polymer typecellulose, synthetic polymer and blends. Results showed that both syngas and aromatics (BTXS) could be recovered from gasification. While cotton is more suitable for syngas production, polyester and blends could produce both syngas and aromatic compounds.
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| 18. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Online Detection of H2O and CO in the Humid Raw Gas from the Gasifier Using Terahertz Spectroscopy
- 2013
-
Ingår i: ICPS, 13 International Conference on Polygeneration Strategies, Sept.5-13, Vienna, Austria. - 9783950275483 ; , s. 51-58
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Konferensbidrag (refereegranskat)abstract
- The integration of a gasifier with a complex multistage synthesis process, such as SNG synthesis, demands a fast monitoring of the gasifier performance. However, despite the availability of standard analyzers for determination of dry gas composition, there are still many practical difficulties remaining in the online measurement of tar and steam in the raw gas. For the detection of steam concentration, electromagnetic waves at terahertz frequencies (102-104 GHz) are promising with regard to development of a robust online measurement device for industrial application. The main reason for the high potential is the low risk for interference with the wide range of other molecules and that the transmission of electromagnetic waves at THz frequencies is rather low sensitive to deposits and particulate matter in the course of the beam compared to the conventional and well established wavelengths like infrared. In the present work, a THz gas spectrometer was designed and constructed to check the feasibility of applying this measurement technique at industrial scale. For this purpose, continuous flows of raw gas with various water and CO contents from the Chalmers gasifier as well as a flue gas with known water content from the biomass combustor were introduced to the spectrometer set-up. H2O and CO compositions in each stream were determined in an online manner. The results confirmed the possibility of applying strong rotational water lines at 448 and 380 GHz to develop reliable devices for online measurement of water vapor with excellent error interval. However, some difficulties were encountered for simultaneous detection CO concentration with water within the frequency range studied in this work (300-500 GHz).
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| 19. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
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Online water vapor detection in the product gas from indirect gasification
- 2013
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The integration of a gasifier into a complex synthesis process, such like SNG synthesis,with several process steps asks for a better monitoring of the gasifier performance.While the dry gas composition is often known, tar concentration andsteam concentration in the raw producer gas are usually not available online. A setof standard analyzers for dry gas composition (GC or NDIR) and online tar measurementcombined with an online water measurement could allow the continuouscalculation of simple mass and energy balances. Those balances, that characterizethe gasification process, could enable the operator to monitor the effects ofvarying fuel properties and eventually counter the effects on the downstreamequipment.For the detection of steam concentration in raw gas electromagnetic waves ofterahertz frequencies (hundreds of gigahertz) are promising with regard to developa robust online measurement device for industrial application. Main reasons for thehigh potential are the low risk for interference with the wide range of other moleculesand the fact that THz frequencies are rather insensitive to deposits and particulatematter in the course of the beam, compared to laser technology at IR.Aiming to test the feasibility of applying this measurement technique in the industrialscale, a gas cell was designed and constructed providing conditions close tothe onsite operation (i.e. T, P, gas composition, etc.) for primary laboratory tests.The experiments were then followed with onsite tests at Chalmers power central.Within those experiments the application of THz spectroscopy as a promisingtechnique for detection and measurement of steam and CO at real industrial processeswas proven. Current report demonstrates the procedure of implementing aTHz spectrometer to acquire data in both laboratory and industrial scale and discusshow those data could be interpreted to gain a precise measurement of desiredgaseous components.
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| 20. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
-
Terahertz Gas Spectrometer
- 2014
-
Ingår i: Swedish Microwave Days March 11-12, 2014, Gothenburg, Sweden.
-
Konferensbidrag (refereegranskat)abstract
- We present a 300-500GHz gas spectrometer built for and practically tested at the 2–4-MW indirect gasifier at the Chalmers Power Center. The primary goal is precise online measurements of H2O vapor and CO concentrations in the producer gas. Experimentally obtained H2O vapor concentration resolution was about 1% at the conditions of 50% VMR and 400 deg.C.
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| 21. |
- Cherednichenko, Serguei, 1970, et al.
(författare)
-
Terahertz Spectroscopy Instrumentation for Thermal Bio-Mass Conversion
- 2016
-
Ingår i: Swedish Microwave Days March 15-16, 2016, Linköping, Sweden. ; , s. 53-
-
Konferensbidrag (refereegranskat)abstract
- THz spectroscopy appears to be a valuable tool for gas sensing in “complicated” environments where conventional IR techniques may not be able to work: high dust and particleconcentrations. We also observe that existing spectral data basis and gas line models have to be updated for specific conditions in combustion and gasification processes.
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| 22. |
- Corcoran, Angelica, 1988, et al.
(författare)
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Ash Properties of Ilmenite Used as Bed Material for Combustion of Biomass in a Circulating Fluidized Bed Boiler
- 2014
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:12, s. 7672-7679
-
Tidskriftsartikel (refereegranskat)abstract
- Both agglomeration of bed material and corrosion of heat transfer equipment are issues related to combustion of biomass in a fluidized bed boiler. The biomass-ash component potassium is considered a major contributor for both phenomena. In this study, the conventionally used bed material, silica sand, was replaced with up to 40 wt % by the natural ore ilmenite in Chalmers 12 MWth circulating fluidized bed (CFB) boiler. In this study the purpose was to evaluate the physical and chemical changes ilmenite undergoes during this process. Close observations revealed that ilmenite underwent segregation of iron to the surfaces and an enrichment of titanium in the particle core. The ash formed a calcium-rich double layer on the particle, surrounding the iron layer. A diffusion of potassium into the particle core was also seen which led to the formation of KTi8O16. In addition to evaluating how ash components interact with the material, the ilmenite was leached and investigated as a possible potassium capturer. Leaching experiments on the used ilmenite showed that calcium and potassium were leachable to a very limited degree, namely, to less than 0.2 and 1 wt %, respectively, of the total content. The diffusion of potassium into the core of the particle could reduce both agglomeration and corrosion issues and could thereby be of great value for the improvement of the resistance of the bed material agglomeration in the fluidized bed boiler.
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| 23. |
- Faust, Robin, 1992, et al.
(författare)
-
Comparison of Ash Layer Formation Mechanisms on Si-Containing Bed Material during Dual Fluidized Bed Gasification of Woody Biomass
- 2020
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 34:7, s. 8340-8352
-
Tidskriftsartikel (refereegranskat)abstract
- Quartz, feldspar, and olivine are minerals commonly used as bed materials for dual fluidized bed gasification of biomass. During their interaction with biomass ash, the materials develop surface layers rich in ash-derived elements. These layers decrease the concentration of tar which is an unwanted side product of gasification. The interactions of quartz, feldspar, and olivine with woody biomass ash leading to the formation of active layers were studied with X-ray diffraction, scanning electron microscopy- energy dispersive X-ray spectroscopy, and iime-of-flight secondary ion mass spectrometry, and the results were compared to calculations done with FactSage. It was found that the interaction causes the formation of three-layered structures for all materials: a Mg-rich surface layer, a Ca-rich intermediate layer, and an inner layer which varies among the three materials. For quartz and feldspar, the integration of Ca and Mg into the structure causes a transition by depolymerizing the tectosilicate structure via an inosilicate intermediate to finally a nesosilicate. As the olivine structure is a nesosilicate from the beginning, no further depolymerization of the silicate structure can occur and a substitution of Mg by Ca occurs, leading to an accumulation of expelled MgO on the surface. The interaction of the materials with K was found to differ, causing melt formation for quartz, a substitution of Na-rich feldspar by K-rich feldspar, and the formation of feldspathoids for alkali feldspar, or retention as a separate phase for olivine.
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| 24. |
- Faust, Robin, 1992, et al.
(författare)
-
Interactions between Automotive Shredder Residue and Olivine Bed Material during Indirect Fluidized Bed Gasification
- 2021
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 35:19, s. 15935-15949
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal conversion of automotive shredder residue (ASR) using indirect fluidized bed gasification was conducted in the Chalmers semi-industrial 2-4-MWth gasifier. The bed material consisted of olivine that was activated through the deposition of biomass ash prior to a 13-day exposure to ASR. The interactions between the bed material and the ASR ash were investigated using XRD, SEM-EDS, and thermodynamic modeling. The deposition of iron (Fe) onto the olivine particles was noted, and this is likely to increase the oxygen-carrying ability of the particles. Furthermore, at the end of the campaign, about one-third of the particles in the bed were found to originate from the ASR ash. These particles were rich in Fe and Si, as well as elements found exclusively in the ASR ash, such as Zn, Ti, and Cu. Some of these particles exhibited a hollow morphology, suggesting a melt state during their formation in the gasifier. In addition, a low level of agglomeration of the ash and olivine particles was detected. Thermodynamic modeling with the FactSage software indicated the formation of slag. This study presents a detailed investigation of the interactions that occur between the bed material and an ash-rich fuel such as ASR. The findings may have applications in demonstrating the induction of oxygen-carrying ability in bed materials or for metal recycling through the separation of ash particles from the bed material.
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| 25. |
- Faust, Robin, 1992, et al.
(författare)
-
Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 1. K-Feldspar
- 2019
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 33:8, s. 7321-7332
-
Tidskriftsartikel (refereegranskat)abstract
- The choice of bed material for biomass gasification plays a crucial role for the overall efficiency of the process. Olivine is the material conventionally used for biomass gasification due to the observed activity of olivine toward cracking of unwanted tars. Despite its catalytic activity, olivine contains high levels of chromium, which complicates the deposition of used bed material. Feldspar has shown the same activity as olivine when used as a bed material in biomass gasification. As opposed to olivine, feldspar does not contain environmentally hazardous compounds, which makes it a preferred alternative for further applications. The interaction of bed material and ash heavily influences the properties of the bed material. In the present study interactions between feldspar and main ash compounds of woody biomass in an indirect gasification system were investigated. Bed material samples were collected at different time intervals and analyzed with SEM-EDS and XRD. The obtained analysis results were then compared to thermodynamic models. The performed study was divided in two parts: in part 1 (the present paper), K-rich feldspar was investigated, whereas Na-rich feldspar is presented in part 2 of the study (DOI: 10.1021/acs.energyfuels.9b01291). From the material analysis performed, it can be seen that, as a result of the bed materials’ interactions with the formed ash compounds, the latter were first deposited on the surface of the K-feldspar particles and later resulted in the formation of Ca- and Mg-rich layers. The Ca enriched in the layers further reacted with the feldspar, which led to its diffusion into the particles and the formation of CaSiO3 and KAlSiO4. Contrary to Ca, Mg did not react with the feldspar and remained on the surface of the particles, where it was found as Mg- or Ca-Mg-silicates. As a result of the described interactions, layer separation was noted after 51 h with an outer Mg-rich layer and an inner Ca-rich layer. Due to the development of the Ca- and Mg-rich layers and the bed material–ash interactions, crack formation was observed on the particles’ surfaces.
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| 26. |
- Faust, Robin, 1992, et al.
(författare)
-
Microscopic investigation of layer growth during olivine bed material aging during indirect gasification of biomass
- 2020
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 266
-
Tidskriftsartikel (refereegranskat)abstract
- Olivine bed material used in an aging experiment for indirect gasification in the Chalmers 2–4-MWth DFB gasifier was investigated with the aim to determine the mechanism of layer formation around the particles upon exposure to gasification conditions. The collected samples were exposed for 1, 2 and 4 days. The development of ash layer around the bed material particles was studied with different analysis methods. Formation of Ca3Mg(SiO4)2 and MgO was confirmed by X-ray diffraction (XRD). Cross-sections of the bed material samples were prepared using Broad Ion Beam (BIB) milling and were further analyzed with Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS). The analysis of the produced cross-sections revealed the formation of a Mg-rich surface layer on top of the Ca-rich ash layer. Minor amounts of K were also found near the sample surface. Based on the results from the characterization techniques, a reaction mechanism involving the transition of Mg2SiO4 with CaO to MgO and Ca3Mg(SiO4)2 was suggested which was confirmed by equilibrium calculations. This mechanism was supported by Transmission Electron Microscopy (TEM) analysis where diffraction patterns corresponding to MgO were found. TEM-EDS line-scan revealed the presence of ash components in the ash layer such as P and Ti at locations coinciding with high levels of Ca which indicates the formation of Ca3(PO4)2 and CaTiO3. The results presented provide detailed information on the composition of the ash layer which can be used to fully understand the mechanism responsible for the formation of catalytically active ash layers.
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| 27. |
|
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| 28. |
- Faust, Robin, 1992, et al.
(författare)
-
Role of Surface Morphology on Bed Material Activation during Indirect Gasification of Wood
- 2023
-
Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 333, Part 1
-
Tidskriftsartikel (refereegranskat)abstract
- Olivine and alkali-feldspar were utilized in separate campaigns in an indirect dual fluidized bed gasification campaign with woody biomass as fuel. After three days, both bed materials were reported to be active towards tar removal and exhibited oxygen-carrying abilities and had formed an ash layer consisting of an outer ash deposition layer and an inner interaction layer.X-ray microtomography analysis concluded that a preferred deposition of ash happens onto convex regions of the bed particles, which results in an increase in thickness of the ash layer over convex regions. This effect is most pronounced for the outer layer which is a product of ash deposition. The inner layer exhibits a homogeneous thickness and is probably formed by interaction of Ca from the outer layer with the particles. Transmission electron microscopy revealed the presence of Fe and Mn on the surface of the particles in a solid solution with Mg. The oxygen-carrying effect which is found for aged particles is therefore attributed to the presence of Fe and Mn on the surface of aged particles. Alkali were found on the surface of both particles which are likely contributing to the catalytic activity of the material towards tar removal.
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| 29. |
- Forero Franco, Renesteban, 1987, et al.
(författare)
-
Correlations between product distribution and feedstock composition in thermal cracking processes for mixed plastic waste
- 2023
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 341
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal conversion can transform the carbon-based waste into valuable chemicals to be further used in the petrochemical industry for a polymeric carbon circular economy. This work's aim was to identify chemical correlations between the thermal-cracking products and the feedstock polymer composition when using highly blended waste streams. The challenges addressed were to: (i) access a pool of experimental data on the monomer recovery potential of real-life, highly blended waste streams; (ii) estimate the polymer constituents of the mixed waste streams; and (iii) formulate a generic and systematic method to identify correlations between feedstock constituents and cracking products. Different post-consumer waste streams were investigated, including cardboard, automotive shredder residues, cable stripping waste, and textile waste. The cracking experiments were performed in a 2–4MWth industrial-scale Dual Fluidized Bed system at 800 °C using steam as fluidization agent. The polymeric constituents of the feedstocks were estimated using a numerical convex optimization method. To identify correlations between the feedstocks and products, a carbon bond-based classification was introduced. The experimental monomer yield ranged from 0.08 kg/kgf to 0.3 kg/kgf (f = feedstock) for the evaluated materials, corresponding to a carbon feedstock conversion rate between 14 % and 44 %. High yields of valuable monomers were obtained for the materials with the highest polyolefin content. The olefin monomer production correlated positively to the amount of aliphatic carbon in the original material and negatively to the carbon contents of the aromatic rings. From the trends observed, it was concluded that a framework based on carbon bond types is a promising approach to identify such correlations, which could serve as predictive tools for monomer recovery based on material's composition and overall process conditions.
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| 30. |
- Forero Franco, Renesteban, 1987, et al.
(författare)
-
Developing a parametric system model to describe the product distribution of steam pyrolysis in a Dual Fluidized bed
- 2023
-
Ingår i: Fuel. - 0016-2361. ; 348
-
Tidskriftsartikel (refereegranskat)abstract
- Steam pyrolysis is a thermochemical process that converts carbon-based materials into valuable gases. In general, the products of the reaction are syngas (H2,CO,CO2), low-molecular-weight hydrocarbon gases (methane, ethylene, and propylene), pyrolytic gasoline and oils, monoaromatic and polyaromatic species (tar), and carbonaceous residues (char) with ashes. However, the intricacy of the reactions comprising the process, the diversity of the product species, and the constraints linked to the sampling and measurement equipment, create a highly complex system. In this work, a method for data representation is presented based on a special Parametric System Model (PSM) that portrays product species measurements in a way that provides relevant information and valuable insights into the process. The method incorporates generic knowledge of the chemical nature of the reactions to create a constrained system in which the data can be expressed in parametric terms with meaningful statistical functions. The evaluated data were obtained from a high-temperature steam pyrolysis process performed in the 2–4-MW Dual Fluidized Bed reactor at Chalmers University using polyethylene as feedstock. The quantities of the hydrocarbon species detected in the gas product were taken for the PSM as a probabilistic system that can be described with a set of distribution functions. The carbon, hydrogen and oxygen balances were taken into account to build a constrained set of equations to find the parameters of the functions. The resulting model was proven to be useful as a prediction tool to quantify unmeasured carbon group species and to estimate process variables, such as the oxygen transport of the bed material. Also, it was demonstrated the potential of the model as a method to identify and estimate inconsistencies in the measurements, which improve the quality of the characterization data. The modeĺs outcomes find application in providing critical information for the control and evaluation of pyrolysis process and downstream operation of biorefineries.
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| 31. |
- González Arias, Judith, 1994, et al.
(författare)
-
Effect of biomass ash on preventing aromatization of olefinic cracking products in dual fluidized bed systems
- 2023
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 338
-
Tidskriftsartikel (refereegranskat)abstract
- In this work, the effect of ash activated olivine on olefinic products cracking and aromatization was assessed. The experiments were carried out in the Chalmers 2–4 MWth dual fluidized bed gasifier, where the feedstock was cracked using steam as fluidization agent, at a reaction temperature of ca. 780–790 °C. Three activation states of the olivine, representing three consecutive days of the campaign, were evaluated. The changes of the permanent gas composition along with the reduction in aromatic species with the time of exposure to biomass ash demonstrate a clear effect of the ash activated olivine on the conversion of olefinic cracking products. The ash activation of the olivine clearly promoted the reactions involving steam. As a consequence, higher yields of permanent gases, mainly H2, CO and CO2, were produced at expenses of the yields of the total aromatic compounds and C4 hydrocarbons and larger. It is concluded that the biomass ash activated olivine promotes the steam reforming path of the C4 and larger hydrocarbon fragments, while avoiding the alternative aromatization route. The results presented here provide useful insights on the opportunities and limitations of ash activated materials in DFB systems when steam cracking linear hydrocarbon feedstocks, e.g., polyolefin-based materials.
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| 32. |
- González Arias, Judith, 1994, et al.
(författare)
-
Steam gasification as a viable solution for converting single-use medical items into chemical building blocks with high yields for the plastic industry
- 2024
-
Ingår i: Resources, Conservation and Recycling. - 0921-3449 .- 1879-0658. ; 201
-
Tidskriftsartikel (refereegranskat)abstract
- This study explores the challenge of recycling single-use medical items due to their non-recyclable nature and associated environmental concerns. To align with the circular economy principles, we propose thermochemical recycling, specifically steam gasification, for carbon atoms recovery. Face masks, plastic syringes, non-woven gowns, and nitrile gloves were tested at different temperatures (700 °C, 750 °C, and 800 °C) in a lab-scale reactor. A significant portion of the carbon in the feedstock could be effectively recovered as valuable chemical building blocks (i.e., olefins, ethane, and BTXS species), enabling their direct application in the chemical industry and reducing reliance on fossil resources. At 700 °C, carbon recovery percentages were approximately 79 % for face masks, 82 % for plastic syringes, 38 % for nitrile gloves, and 76 % for non-woven gowns. Higher temperatures led to reduced recovery due to secondary cracking reactions. Overall, this study highlights the circularity potential of single-use medical waste contributing to sustainable waste management in healthcare.
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| 33. |
- Gustafsson, Eva, et al.
(författare)
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Characterization of Particulate Matter in the Hot Product Gas from Indirect Steam Bubbling Fluidized Bed Gasification of Wood Pellets
- 2011
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:4, s. 1781-1789
-
Tidskriftsartikel (refereegranskat)abstract
- This study characterized the particulate matter (PM) formed during the indirect steam bubbling fluidized bed gasification of wood pellets at atmospheric pressure. A system including a dilution probe, a bed of granular activated carbon, and a thermodenuder was used to sample the PM at high temperature with the aim of separating it from condensing inorganic vapors and tars. The particle mass size distribution was bimodal with a fine mode in the <0.5-μm size range and a dominating coarse mode in the >0.5-μm size range. The coarse mode was representatively characterized while condensing inorganic vapors and tars complicated the evaluation of the results for the fine-mode PM. Morphological analysis of the PM indicated that the char content was low. The inorganic fraction was dominated by potassium and chlorine for fine-mode PM and calcium and silicon for coarse-mode PM.
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| 34. |
- Hannl, Thomas Karl, 1993-, et al.
(författare)
-
Layer Formation on Feldspar Bed Particles during Indirect Gasification of Wood. 2. Na-Feldspar
- 2019
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 33:8, s. 7333-7346
-
Tidskriftsartikel (refereegranskat)abstract
- Selecting a suitable bed material for the thermochemical conversion of a specific feedstock in a fluidized bed system requires identification of the characteristics of potential bed materials. An essential part of these characteristics is the interaction of the bed material with feedstock ash in a fluidized bed, which leads to layer formation and morphology changes. For this purpose, the interaction of feldspar bed material with the main ash-forming elements in wood ash (Ca, K, Mg, Si) in an indirect gasification system was analyzed using SEM-EDS, XRD, and thermodynamic modeling. In part 1 of this work (DOI: 10.1021/acs.energyfuels.9b01291), the layer formation on K-feldspar dominated by Ca reaction and ash deposition was investigated. The aim of this second part of the work was to determine the time-dependent layer formation on Na-feldspar and compare the results with the findings for K-feldspar. Interaction of Na-feldspar with ash-derived elements resulted in different layers on Na-feldspar: K reaction layers, where K replaced Na and Si shares decreased; Ca reaction layers, where Ca enriched and reacted with the Na-feldspar; and ash deposition layers, where wood ash elements accumulated on the surface. Ca reaction layers were formed first and became continuous on the surface before K reaction layers and ash deposition layers were detected. Cracks and crack layer formation in the Na-feldspar particles were found after several days of operation. The layer compositions and growth rates indicate that the diffusion of Ca and K plays an essential role in the formation of Ca reaction and K reaction layers. The reaction with Ca and the crack formation coincide with the interaction previously found for quartz and K-feldspar. In contrast to K-feldspar, Na-feldspar showed high potential for reaction with K. The findings indicate that the reaction of Na-feldspar with ash-derived K makes Na-feldspar a less stable bed material than K-feldspar during the thermochemical conversion of K-rich feedstocks in a fluidized bed system.
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| 35. |
- Heyne, Stefan, 1979, et al.
(författare)
-
Bio-SNG Production via Gasification - Process Integration Aspects for Improving Process Performance
- 2013
-
Ingår i: Proceedings of the 21st European Biomass Conference and Exhbition. - 2282-5819. - 9788889407530 ; , s. 1291 - 1304
-
Konferensbidrag (refereegranskat)abstract
- This paper presents results from a comprehensive process integration study of different process alternatives for Bio-SNG production based on biomass gasification. The influence of the different conversion steps in the process chain – drying, gasification, gas cleaning, methanation, and gas upgrade – on the overall process performance is investigated. Process bottlenecks as well as heat and material integration aspects are highlighted. Using future energy market scenarios, the energetic, economic, and carbon footprint performance of different process configurations are evaluated from a system perspective. About 63 MLHV of Bio-SNG can be produced from a process converting 100 MWth,LHV (20 wt-% moisture) of forestry residues. Drying of the feedstock from a natural moisture content of 50 wt-% using internal process heat recovery is shown to be important for increasing the process energy efficiency, while the choice of gasification and methanation technology is shown to be of minor importance from a process integration perspective. Amine-based CO2 separation for gas upgrade is shown to be preferable to membrane or pressure-swing adsorption based options both from an economic and Bio-SNG yield perspective. Production cost estimates in the range of 103–112 €2010/MWhSNG indicate that price parity with fossil natural gas would require specific and significant support policies.
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| 36. |
- Heyne, Stefan, 1979, et al.
(författare)
-
Coal and biomass gasification for sng production
- 2016
-
Ingår i: Synthetic Natural Gas from Coal and Dry Biomass, and Power?to?Gas Applications. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9781119191339 ; , s. 5-40
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Within the production of synthetic natural gas - basically methane-from solid feed stock such as coal or biomass the major conversion step is gasification, generating a product gas containing a mixture of permanent and condensable gases, as well as solid residues. The gasification step can be conducted in different atmospheres and using different reaction agents. This chapter discusses the role of gasification for the overall substitute natural gas (SNG) process, and the basic thermodynamic aspects within gasification. The gasification process is a series of different conversions involving both homogeneous and heterogeneous reactions. The basic steps from solid fuel to product gas are drying, pyrolysis, and gasification. From a technological viewpoint, there basically exist three different gasification reactor types that are used at large scale: fixed bed reactors, entrained flow reactors, and fluidized bed reactors. Coal is mainly used in entrained flow gasification or fixed bed units, whereas biomass gasification is mostly done in fluidized bed reactors. © 2016 by John Wiley & Sons, Inc. All rights reserved.
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| 37. |
- Heyne, Stefan, 1979, et al.
(författare)
-
Integration study for alternative methanation technologies for the production of synthetic natural gas from gasified biomass
- 2010
-
Ingår i: Chemical Engineering Transactions. - 2283-9216. ; 21, s. 409-414
-
Konferensbidrag (refereegranskat)abstract
- This paper analyzes the integration of two different methanation technologies – fixed bed adiabatic and fluidised bed isothermal - in a SNG production process and the consequences for the overall process energy conversion performance. The different operating conditions of the two methanation technologies lead to a change in temperature levels and quantities of recoverable heat, respectively, but also to differences in the overall processes’ power consumption. Using pinch methodology for optimal internal heat recovery in combination with flowsheeting software (ASPEN Plus), the two methanation alternatives are fitted into the SNG production process. The potential power production from recovered process heat is analysed based on the Carnot efficiency and compared to the overall power consumption within the SNG process. Both methanation alternatives perform equally within the given boundary conditions, resulting in an output of SNG of 63.3 MWLHV per 100 MWLHV dry fuel input and a ratio of about 1.22 between theoretical power production and overall power consumption.
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| 38. |
- Hildor, Fredrik, 1992, et al.
(författare)
-
Tar characteristics generated from a 10 kW th chemical-looping biomass gasifier using steel converter slag as an oxygen carrier
- 2023
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 331
-
Tidskriftsartikel (refereegranskat)abstract
- Tar management is one of the key components to achieve high energy efficiency and low operational costs connected to thermal gasification of biomass. Tars contain a significant amount of energy, and unconverted tars result in energy efficiency losses. Also, heavy tars can condense downstream processes, resulting in increased maintenance. Dual fluidized beds for indirect gasification operated with active bed material can be a way to better convert and control the tar generated in the process. Using an active material to transport oxygen in an indirect dual reactor gasification setup is referred to as chemical-looping gasification (CLG). A higher oxidative environment in the gas phase, in addition to possible catalytic sites, could mean lower yields in comparison to normal indirect gasification. This paper investigates the effect of using Steel converter slag (LD slag), a byproduct of steel manufacturing, as an oxygen-carrying bed material on tar species generated in a 10 kWth dual fluidized bed biomass gasifier. The results are compared to the benchmark oxygen carrier ilmenite and conventional silica sand. Three different solid biofuels were used in the reactor system: steam exploded pellets, pine forest residue and straw. Tar was absorbed from the raw syngas using a Solid Phase Adsorption (SPA) column and was analyzed using GC-FID. Bench-scale experiments were also performed to investigate benzene conversion of LD slag and ilmenite at different oxidation levels. The findings of this study suggest that oxygen carriers can be used to decrease the tars generated in a dual fluidized bed system during gasification. Phases in LD slag possess catalytic properties, resulting in a decreased ratio of heavy tar components compared to both ilmenite and sand. Temperature and fuel load showed a significant effect on the tar generation compared to the circulation and steam ratio in this reactor system. Increased temperature generated lower tar yields and lower ratios of heavy tar components for LD slag in contrast to sand.
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| 39. |
- Hoseini Hooshyar, Hamed, 1986, et al.
(författare)
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Initial corrosion attack of 304L and T22 in 2 MW biomass gasifier: a microstructural investigation
- 2015
-
Ingår i: Materials at High Temperatures. - 0960-3409. ; 32:1-2, s. 197-204
-
Tidskriftsartikel (refereegranskat)abstract
- The work investigates the initial corrosion attack on a low alloyed steel and a stainless steel in a 2 MW test gasifier. The gasifier environment generates homogenous deposits that consist mainly of carbon containing species, potassium sulphate, potassium chloride and zinc sulphide. The stainless steel exhibits better corrosion resistance compared to the low alloyed steel and the analysis indicates a protective thin scale covering parts of the surface after 4 h exposure. However, in some areas the oxide scale has lost its protective properties and thicker oxide scales are seen. The thick oxide islands consist of an inward growing Fe,Cr,Ni oxide and an outward growing iron oxide. The low alloyed steel shows a more homogenous and faster initial corrosion attack. The thick scales exhibit a sharp straight line in the middle of the scale that separates the bottom spinel oxide from the outer iron rich parts of the scale. It is considered that this flat interface corresponds to the original sample surface
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| 40. |
- Israelsson, Mikael, 1985, et al.
(författare)
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Assessment of the Solid-Phase Adsorption Method for Sampling Biomass-Derived Tar in Industrial Environments
- 2013
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:12, s. 7569-7578
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Tidskriftsartikel (refereegranskat)abstract
- Low-temperature gasification of biomass is a primary process step for production of biofuels or electricity using gas-fired engines or turbines. In addition to the desired product gas, the raw gas produced through gasification inevitably contains condensable hydrocarbons, known collectively as tar. The amount and composition of the tar have relevance for the efficiencies of the downstream processes. Tar can be measured using both online and off-line methods. However, many of these methods currently lack information regarding their implementation and accuracy levels for large-scale systems. In this work, the Solid-Phase Adsorption (SPA) method for measuring tar in industrial applications is evaluated. The individual steps of the method were examined for their effects on the overall performance of the analysis. Sample collection was found to be the most prominent source of error, and this was mainly due to human factors. Omitting to determine the temperature and pressure of the sampled gas contributed to this error, as the sampled volume of gas under normal conditions could not be correctly calculated. Inconsistencies in the treatment and storage of the collected samples were shown to affect the more volatile species with boiling points similar to that of benzene. The gas chromatography (GC) analysis was performed with satisfying accuracy. However, the reliability of the estimations of the average composition and dew-point of the tar mixture were dependent upon the amount of the identified species. The current implementation of the SPA method yields values with a relative standard deviation within 10% for the majority of the compounds in a given sample. However, in line with the result of previous studies, the tar species with boiling points between those of benzene and xylene (i.e., the BTX compounds) were measured with a lower accuracy than those of heavier tars.
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| 41. |
- Kiminaitė, Ieva, et al.
(författare)
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Syngas Production from Protective Face Masks through Pyrolysis/Steam Gasification
- 2023
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Ingår i: Energies. - 1996-1073 .- 1996-1073. ; 16:14
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has caused a heavy expansion of plastic pollution due to the extensive use of personal protective equipment (PPE) worldwide. To avoid problems related to the entrance of these wastes into the environment, proper management of the disposal is required. Here, the steam gasification/pyrolysis technique offers a reliable solution for the utilization of such wastes via chemical recycling into value-added products. The aim was to estimate the effect of thermo-chemical conversion temperature and steam-to-carbon ratio on the distribution of gaseous products obtained during non-catalytic steam gasification of 3-ply face masks and KN95 respirators in a fluidized bed reactor. Experimental results have revealed that the process temperature has a major influence on the composition of gases evolved. The production of syngas was significantly induced by temperature elevation from 700 °C to 800 °C. The highest molar concentration of H2 gases synthesized from both types of face masks was estimated at 800 °C with the steam-to-carbon ratio varying from 0 to 2. A similar trend of production was also determined for CO gases. Therefore, investigated thermochemical conversion process is a feasible route for the conversion of used face masks to valuable a product such as syngas.
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| 42. |
- Knutsson, Pavleta, 1980, et al.
(författare)
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Potassium speciation and distribution for the K2CO3 additive-induced activation/deactivation of olivine during gasification of woody biomass
- 2019
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 248, s. 538-544
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Tidskriftsartikel (refereegranskat)abstract
- The GoBiGas plant, which comprises a 32-MW th dual fluidized bed gasifier, was constructed as a demonstration unit for converting biomass to biomethane via gasification. On several occasions during the commissioning of the plant, low activity of the olivine bed generated a high content of tar in the produced gas, which was deleterious to the downstream equipment. The problem was attributed to a deficiency of ash constituents, and the solution was to control activation of the bed material through the addition of K 2 CO 3 to the process. This enabled extended operational periods without tar-related issues. The achieved activity could be lost during interrupted operation at which time the activation procedure had to be repeated. In the present paper analysis of the bed material samples extracted upon activation and after loss of activity using Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS)showed similar morphologies for the ash layers formed around the olivine particles. The observed differences mainly related to the distributions of potassium (K)across the layers. Furthermore, surface analysis showed differences in K speciation within the outer regions. K solubility tests and X-ray photoelectron spectroscopy analyses indicated that K was present as an oxide/hydroxide rather than as a silicate on the surface of the active olivine. The presented results are of major relevance for the operation of dual fluidized bed gasifiers with fuels that are potassium-lean when ash components need to be supplied as additives.
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| 43. |
- Knutsson, Pavleta, 1980, et al.
(författare)
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Role of potassium in the enhancement of the catalytic activity of calcium oxide towards tar reduction
- 2018
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 229, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- Gasification in fluidized bed systems is considered to be a highly promising alternative for the thermal conversion of biomass. A major challenge for this process is the formed tars, which represent a loss of energy from the product gas and entail additional costs for their removal. Olivine is considered to be the most effective catalytic bed material in terms of its impact on tar levels in the product gas. Additions and modifications to olivine have revealed the potential to enhance its catalytic activity. In the present study, the effect of the addition of K 2 CO 3 to the gasification process on the tar decomposition capability of olivine were evaluated. The effect of the added K 2 CO 3 on the product gas was assessed in the 30-MWth pilot gasification plant GoBiGas. Once dec reases in the tar level were detected, samples of the bed material were extracted from the system and evaluated for morphological and chemical changes related to the observed catalytic effect. SEM-EDX and XPS analyses of the surfaces of the olivine particles indicate that the additive is involved in the formation of mixed oxides of Ca and K within the outermost layer of the olivine particles. DFT modeling showed that the formation of mixed Ca and K oxides changes the oxidation potential of the surface, which may explain the increased activity of ash-coated olivine towards tar reduction.
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| 44. |
- Kopyscinski, J., et al.
(författare)
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Synthetic natural gas from wood: Reactions of ethylene in fluidised bed methanation
- 2013
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Ingår i: Applied Catalysis A: General. - : Elsevier BV. - 1873-3875 .- 0926-860X. ; 462-463, s. 150-156
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis step in the production of synthetic natural gas from wood, i.e. the methanation, was investigated by systematic experiments with commercial nickel catalyst in a micro-fluidised bed reactor. Ethylene in the feed is always converted completely; dominantly serial reactions of ethylene to ethane and further to methane under isothermal fluidised bed methanation conditions could be shown. Lower temperatures favour the production of the intermediate ethane while high temperatures cause the formation of carbon depositions and carbon whiskers. Applying optimal operation conditions, the hydrogenation of the unsaturated olefin not only avoids the deposition of carbon or coke, but also leads to an increase of the higher heating value (HHV) of the produced (raw) SNG. © 2013 Elsevier B.V. All rights reserved.
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| 45. |
- König, C.F.J., et al.
(författare)
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Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy
- 2014
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 113, s. 1895-1901
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Tidskriftsartikel (refereegranskat)abstract
- Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature "chemical looping desulfurization" process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO2. Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a "chemical looping desulfurization" reactor. The "fuel reactor" gas contained H2, CO, CH4 and H2S, similar as in the producer gas, and the "oxidizing reactor" contained diluted O2. Mass spectrometry showed that most of the H2S is taken up by the sample in the "fuel reactor" part, while also some unwanted SO2 is generated in the "fuel reactor" part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn3O4 is transformed in the presence of H2S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn3O4 oxidizes some H2S to the undesired SO2 in the fuel reactor. Upon exposure to O2, MnS is again oxidized to Mn3O4 via MnO, releasing SO2. The presence of CO and/or CH4 in the fuel reactor has no effect on this mechanism. Measuring the structure-performance relationship of gas cleaning materials with in situ methods will enable knowledge-based materials development for improved performance. © 2013 Elsevier Ltd. All rights reserved.
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| 46. |
- Larsson, Anton, 1984, et al.
(författare)
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Evaluation of Performance of Industrial-Scale Dual Fluidized Bed Gasifiers Using the Chalmers 2–4-MWth Gasifier
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:1, s. 6665-6680
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Tidskriftsartikel (refereegranskat)abstract
- A general approach to evaluating the performance of industrial-scale dual fluidized bed (DFB) gasifiers was developed in this work. The approach is intended to simplify comprehensive evaluation of DFB gasifiers and to highlight important parameters, some of which are often missed or omitted in the literature. By applying this procedure, experimental results can be generalized, which is verified in this work using the Chalmers 2–4-MWth DFB gasifier. In a DFB gasifier, some of the fuel is converted to the desired calorific gas, while the remaining portion is combusted to meet the heat demands of the process. As shown here, the total heat demands limit the amount of chemical energy that can be restored from the fuel into the produced gas, whereby the main heat demands are from the drying and heating of the fuel, in addition to heating the combustion air and steam. By establishing a heat balance across the system, the chemical efficiency can be estimated. With lower heat demands, higher chemical efficiency is achievable, whereas with higher heat demands, more of the fuel must be burned and a lower chemical efficiency is achieved. It is experimentally complicated to quantify the level of fuel conversion and heat demands of a DFB gasification system. In this work, an experimental procedure is presented and implemented using the Chalmers gasifier to quantify the fuel conversion and heat demands. Furthermore, it was investigated how a variation in the amount of steam used for fluidization of the gasifier affects fuel conversion and other important parameters. To establish a reference case, silica sand was used as bed material and wood pellets was used as fuel to minimize the effects of ash and the bed material. By increasing the level of fluidization steam, the average residence time of the gas was decreased and the gas temperature, gas velocity, and steam-to-fuel ratio were increased, which resulted in increased conversion (up to 36%) of organic compounds (OC). However, limited char conversion was achieved (0%–4%), and the chemical efficiency remained unaffected by the amount of steam added to the process. The chemical efficiency of the Chalmers gasifier was determined to be 74% when using wood pellets as fuel. This is comparable to results from thermo-economic modeling of second-generation biofuels production processes, which, based on the heat demand, report the chemical efficiency of the DFB gasifier as being in the range of 74%–77% to maximize the overall efficiency. This shows that the required chemical efficiency is achieved, even with low char conversion, when using a fuel with a high content of volatiles, such as wood pellets.
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| 47. |
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| 48. |
- Larsson, Anton, 1984, et al.
(författare)
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Steam gasification of biomass – Typical gas quality and operational strategies derived from industrial-scale plants
- 2021
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 212
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Tidskriftsartikel (refereegranskat)abstract
- Steam gasification enables the thermochemical conversion of solid fuels into a medium calorific gas that can be utilized for the synthesis of advanced biofuels, chemicals or for heat and power production. Dual fluidized bed (DFB) gasification is at present the technology applied to realize gasification of biomass in steam environment at large scale. Few large-scale DFB gasifiers exist, and this work presents a compilation and analysis of the data and operational strategies from the six DFB gasifiers in Europe. It is shown that the technology is robust, as similar gas quality can be achieved despite the differences in reactor design and operation strategies. Reference con-centrations of both gas components and tar components are provided, and correlations in the data are in-vestigated. In all plants, adjusting the availability and accessibility to the active ash components (K and Ca) was the key to control the gas quality. The gas quality, and in particular the tar content of the gas, can conveniently be assessed by monitored the concentration of CH4 in the produced gas. The data and experience acquired from these plants provide important knowledge for the future development of the steam gasification of biomass.
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| 49. |
- Larsson, Anton, 1984, et al.
(författare)
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Using Ilmenite To Reduce the Tar Yield in a Dual Fluidized Bed Gasification System
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:4, s. 2632-2644
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification plays an important role in the emerging production of second-generation biofuels. One of the major challenges facing biomass gasification is to find simple and efficient ways to reform tar components. While the tar causes operational problems, it can be reformed to increase the chemical efficiency of the gasification process. With respect to tar reforming, catalytic materials are of special interest. Many of the materials that have been proposed as promising catalysts are metal oxide-based materials. However, metal oxides also have the ability to transport oxygen when subjected to alternating oxidizing and reducing atmospheres, similar to that which occurs in a dual fluidized bed gasification system. In this work, ilmenite was used as the catalytic material in the Chalmers 2-4 MWth dual fluidized bed gasifier to decrease the yield of tar. The ilmenite was mixed with the silica sand, which was used as the bed material, to investigate how the level of ilmenite affected chemical efficiency and tar yield. Furthermore, energy balance calculations were established to elucidate the general aspects of oxygen transport in dual fluidized bed gasification systems. The results presented in this paper reveal that adding low levels of ilmenite reduces the tar yield by similar to 50%(mass). However, the oxygen transport induced by ilmenite caused a reduction in the chemical efficiency of the gasifier and the heating value of the gas, compared to using 100% silica sand as the bed material. The impact of adding ilmenite was found to be dependent upon the operational conditions of the gasifier; a low fluidization velocity gave the highest reduction of the tar yield, whereas higher fluidization velocities led to increased levels of heavy components. Overall, the use of ilmenite as a catalyst for reduction of the yield of tar appears promising, provided that the level of oxygen transport can be restricted.
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| 50. |
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