| 1. |
- Fu, Jiapeng, et al.
(author)
-
Identification of the running status of membrane walls in an opposed fired model boiler under varying heating loads
- 2020
-
In: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 173, s. 1-9
-
Journal article (peer-reviewed)abstract
- To understand the running status of membrane walls in an opposite firing boiler, a scale-down model furnace was established, and the temperature, heat flux, strain and stress distributions are investigated under four heating loads. Results show that the average membrane wall temperature and heat flux present a continuous increase from 42 oC and 16 W/m2 to 96 oC and 50 W/m2, respectively, with the heating load increase from 25% to full load. The average strain and stress also rise from 88.7 µm and 0.094 MPa to 152.5 µm and 0.148 MPa when the heating load increases from 25% to 50%, but then they keep stable when further increasing the heating load. General distribution patterns of each tested parameter are found relatively similar under varying heating loads. High strain and stress distributions are always detected at the middle left zone of side walls and the middle of the rear wall, where wall temperatures are measured high. External fixed constraints and high-temperature thermal strain is found jointly affecting the strain and stress distribution of the membrane wall. A simplified mechanism of how the strain and stress on boiler membrane walls evolve is proposed after comprehensive discussion of the measurement results.
|
|
| 2. |
- Jiang, Junfei, et al.
(author)
-
Partial oxidation of filter cake particles from biomass gasification process in the simulated product gas environment
- 2018
-
In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:2, s. 1703-1710
-
Journal article (peer-reviewed)abstract
- Filtration failure occurs when filter media is blocked by accumulated solid particles. Suitable operating conditions were investigated for cake cleaning by partial oxidation of filter-cake particles (FCP) during biomass gasification. The mechanism of the FCP partial oxidation was investigated in a ceramic filter and by using thermo-gravimetric analysis through a temperature-programmed route in a 2 vol.% O2–N2 environment. Partial oxidation of the FCP in the simulated product gas environment was examined at 300–600°C in a ceramic filter that was set and heated in a laboratory-scale fixed reactor. Four reaction stages, namely drying, pre-oxidation, complex oxidation and non-oxidation, occurred in the FCP partial oxidation when the temperature increased from 30°C to 800°C in a 2 vol.% O2–N2 environment. Partial oxidation was more effective for FCP mass loss from 275 to 725°C. Experimental results obtained in a ceramic filter indicated that the best operating temperature and FCP loading occurred at 400°C and 1.59 g/cm2, respectively. The FCP were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy and Brunaeur–Emmett–Teller before and after partial oxidation. Fourier-transform infrared spectroscopy analysis revealed that partial oxidation of the FCP can result in a significant decrease in C–Hn (alkyl and aromatic) groups and an increase in C=O (carboxylic acids) groups. The scanning electron microscopy and Brunaeur–Emmett–Teller analysis suggests that during partial oxidation, the FCP underwent pore or pit formation, expansion, amalgamation and destruction.
|
|
| 3. |
- Ahmad, Waqar, et al.
(author)
-
Benzene conversion using a partial combustion approach in a packed bed reactor
- 2022
-
In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 239:Part C
-
Journal article (peer-reviewed)abstract
- This study investigates the partial combustion technique for tar conversion using a modified experimental set up comprising a packed bed reactor with bed-inside probe for air supply. Simulated producer gas (SPG) and benzene were selected as a real producer gas alternative and model tar component respectively. The benzene conversion was investigated under different experimental conditions such as reactor temperature (650–900 °C), packed bed height (0–12 cm), residence time (1.2–1.9 s), air fuel ratio (0.2 and 0.3) and SPG composition. The results showed insignificant effect of temperature over benzene conversion while air fuel ratio of 0.3 caused high benzene conversion than at 0.2. Absence of packed bed lead high benzene conversion of 90% to polyaromatic hydrocarbons (PAHs) compared to similar low PAHs free benzene conversion of 32% achieved at both packed heights. In SPG composition effect, H2 and CH4 had a substantial inverse effect on benzene conversion. An increase in H2 concentration from 12 to 24 vol% increased the benzene conversion from 26 to 45% while an increase in CH4 concentration from 7 to 14 vol% reduced the benzene conversion from 28 to 4%. However, other SPG components had insignificant impacts on benzene conversion.
|
|
| 4. |
- Ahmad, Waqar, et al.
(author)
-
Coke-free conversion of benzene at high temperatures
- 2023
-
In: Journal of the Energy Institute. - : Elsevier. - 1743-9671 .- 1746-0220. ; 109
-
Journal article (peer-reviewed)abstract
- This study investigates the conversion of benzene in a novel highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 °C. The influences of packed bed presence, reforming medium (steam and CO2), gas flow rate and benzene concentration on steady state benzene conversion are examined. In presence of packed bed, benzene conversions of 52, 75, and 84% were achieved with combined steam and CO2 reforming at 1000, 1050, and 1100 °C, respectively. Whereas, benzene conversion of 65% without the packed bed at 1000 °C experienced a continuous increase in differential upstream pressure (DUP) of high temperature (HT) filter at reactor downstream due to deposition of in situ generated coke. High concentrations of generated CO and H2 of 2.3 and 6 vol% with packed bed than 1.4 and 4.7 vol% without the packed respectively, were achieved. CO2 reforming achieved high benzene conversions of 68–98% than 42–80% achieved with stream reforming at packed bed reactor temperatures of 1000–1100 °C. The results indicated that presence of ɣ-Al2O3 packed bed with possible surface reactions directed the conversion of benzene to combustible gases instead of coke. Hence, ɣ-Al2O3 packed bed reactor could be a suitable choice for coke-free conversion of tar of gasifier producer gas.
|
|
| 5. |
- Ahmad, Waqar, et al.
(author)
-
Investigation of different configurations of alumina packed bed reactor for coke free conversion of benzene
- 2024
-
In: Chemical engineering research & design. - : Elsevier. - 0263-8762 .- 1744-3563. ; 201, s. 433-445
-
Journal article (peer-reviewed)abstract
- Conversion of producer gas tar without coke generation is a great challenge. This study investigates conversion of tar model benzene using different configurations of highly non-porous ɣ-Al2O3 packed bed reactor at 1000–1100 0C. The configurations comprised of different positions (relative to top (P1), center (P2) and bottom (P3) of reactor furnace), heights (5, 13 and 25 cm) and particles sizes (0.5, 3 and 5 mm) of alumina packed bed. Steam and CO2 were used as reforming media for tested benzene concentrations (0.4–1.8 vol%). The results showed benzene conversions of 48–91% with negligible steady thin coke generation using a packed bed (height: 25 cm, particles size: 3 mm) at P1. Whereas, relative high benzene conversions of 63–93 and 68–95% at P2 and P3 respectively with unsteady thick coke generation at benzene concentrations greater than 0.4 vol% increased differential upstream pressures (DUPs) of beds. Similar unsteady coke generation at benzene concentrations greater than 0.8 vol% and temperature of 1100 0C was observed with packed beds of heights of 5 and 13 cm, and particles size of 0.5 mm at P1. Generation of unsteady coke with condensed structure as evidenced by its characterization was attributable to increased benzene polymerization and reduced bed surface gasification reactions due to improperly installed packed bed. Developed kinetic model predicted well the generated coke. As conclusion, properly installed alumina packed bed pertaining to tar concentration and other experimental conditions may inhibit coke generation during tar conversion.
|
|
| 6. |
- Asuquo, Asuquo Jackson, et al.
(author)
-
Green heterogeneous catalysts derived from fermented kola nut pod husk for sustainable biodiesel production
- 2024
-
In: International Journal of Green Energy. - : Taylor & Francis Group. - 1543-5075 .- 1543-5083.
-
Journal article (peer-reviewed)abstract
- The use of green heterogeneous catalysts that are obtained from waste agricultural biomass can make the production of biodiesel more economical. In this research, three solid base heterogeneous catalysts (Catalyst A, B, and C) were synthesized from kola nut pod husks, and the synergistic effects of the elemental composition on catalytic activities for biodiesel production were studied. The results revealed a high surface area of Catalysts A, B, and C at 419.90 m2/g, 430.54 m2/g, and 432.57 m2/g, respectively. Their corresponding pore diameters are 3.53 nm, 3.48 nm, and 3.32 nm, showing that the catalysts are mesoporous in nature. The X-ray Fluorescence (XRF) results revealed the presence of a variety of alkaline earth metals and their corresponding metal oxides in substantial amounts. Catalyst A was produced with the highest concentration of calcium at 40.84 wt.% and calcium oxide at 68.02 mole%. The substantial concentration of other elements, such as potassium, magnesium, and aluminum, and their corresponding metal oxides are the proof of high catalytic activity of the produced green catalysts. The high CaO contents of all three produced catalysts and their high surface areas indicate their strong potential for good catalytic activities applied to the synthesis of biodiesel.
|
|
| 7. |
- Biollaz, S., et al.
(author)
-
Gas analysis in gasification of biomass and waste : Guideline report: Document 1
- 2018
-
Reports (peer-reviewed)abstract
- Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). In practice, a trade-off between reliability, accuracy and cost has to be reached when selecting the proper analysis technique for a specific application. The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to(biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. The report is composed of a set of 2 documents. Document 1(the present report) describes the available analysis techniques (both commercial and underdevelopment) for the measurement of different compounds of interest present in gasification gas. The objective is to help the reader to properly select the analysis technique most suitable to the target compounds and the intended application. Document 1 also describes some examples of application of gas analysis at commercial-, pilot- and research gasification plants, as well as examples of recent and current joint research activities in the field. The information contained in Document 1 is complemented with a book of factsheets on gas analysis techniques in Document 2, and a collection of video blogs which illustrate some of the analysis techniques described in Documents 1 and 2.This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.
|
|
| 8. |
- Biollaz, S., et al.
(author)
-
Gas analysis in gasification of biomass and waste : Guideline report: Document 2 - Factsheets on gas analysis techniques
- 2018
-
Reports (peer-reviewed)abstract
- Gasification is generally acknowledged as one of the technologies that will enable the large-scale production of biofuels and chemicals from biomass and waste. One of the main technical challenges associated to the deployment of biomass gasification as a commercial technology is the cleaning and upgrading of the product gas. The contaminants of product gas from biomass/waste gasification include dust, tars, alkali metals, BTX, sulphur-, nitrogen- and chlorine compounds, and heavy metals. Proper measurement of the components and contaminants of the product gas is essential for the monitoring of gasification-based plants (efficiency, product quality, by-products), as well as for the proper design of the downstream gas cleaning train (for example, scrubbers, sorbents, etc.). The deployment and implementation of inexpensive yet accurate gas analysis techniques to monitor the fate of gas contaminants might play an important role in the commercialization of biomass and waste gasification processes.This special report commissioned by the IEA Bioenergy Task 33 group compiles a representative part of the extensive work developed in the last years by relevant actors in the field of gas analysis applied to (biomass and waste) gasification. The approach of this report has been based on the creation of a team of contributing partners who have supplied material to the report. This networking approach has been complemented with a literature review. This guideline report would like to become a platform for the reinforcement of the network of partners working on the development and application of gas analysis, thus fostering collaboration and exchange of knowledge. As such, this report should become a living document which incorporates in future coming progress and developments in the field.
|
|
| 9. |
- Cao, Wenhan, et al.
(author)
-
Release of potassium in association with structural evolution during biomass combustion
- 2021
-
In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 287, s. 1-9
-
Journal article (peer-reviewed)abstract
- A mechanistic understanding of potassium release is essential to mitigate the potassium-induced ash problems during biomass combustion. This work studies the effects of operational condition on the potassium release and transition during the combustion of wheat straw, and elucidate the release potential of potassium associated with the structural change of biomass particles. The combustion tests were carried out in a laboratory-scale reactor, working in a wide range of temperatures and heating rates. It was found that the combustion of biomass sample at a temperature up to 1000 °C results in a release of over 60% of its initial potassium content. Raising the heating rate from 8 °C/min to 25 °C/min could lead to an additional release of up to 20% of the initial amount of potassium. A three-stage potassium release mechanism has been concluded from this work: the initial-step release stage (below 400 °C), the holding stage (400–700 °C) and the second-step release stage (above 700 °C). Comprehensive morphology analysis with elemental (i.e. K, S, O, Si) distribution was carried out; the results further confirmed that potassium is likely to exist inside the stem-like tunnel of biomass particles, mainly in forms of inorganic salts. During the heating-up process, the breakdown and collapse of biomass particle structure could expose the internally located potassium and thus accelerate the release of potassium and the transform of its existing forms. Lastly, a detailed temperature-dependent release mechanism of potassium was proposed, which could be used as the guidance to mitigate the release of detrimental potassium compounds by optimising the combustion process.
|
|
| 10. |
- Fu, Dianliang, et al.
(author)
-
Improved pinch-based method to calculate the capital cost target of heat exchanger network via evolving the spaghetti structure towards low-cost matching
- 2022
-
In: Journal of Cleaner Production. - : Elsevier. - 0959-6526 .- 1879-1786. ; 343
-
Journal article (peer-reviewed)abstract
- Ahead of heat exchanger network (HEN) design, setting an optimal pinch temperature difference for pinch analysis depends vitally on the capital cost target. Conventional methods based on the spaghetti (SPA) structure ignoring matching optimization might result in calculated cost targets of large deviations. This work evolved the SPA structure via four stages by shifting energy towards low-cost matching. The fourth structure evolved from the SPA structure (ESPA-IV structure) with the lowest-cost matching after loops elimination forms the base to establish the ESPA method. It is validated by numerical experiment and applied to a case reported in literature, meanwhile comparisons are always made to the SPA method. The numerical experiment proves that the ESPA method can obtain capital cost targets with higher accuracy than the SPA method. The target deviations (often within ±5%) given by the ESPA method are much lower than those (well above 10%) derived by the SPA method. In the case study, the given HEN is further optimized as hinted by ESPA method results. Of two target methods, the cost target indicated by ESPA method is closer to the optimum capital cost newly derived after optimization. The high accuracy of the ESPA method is further verified.
|
|
| 11. |
- Fu, Jiapeng, et al.
(author)
-
One-step rapid pyrolysis activation method to prepare nanostructured activated coke powder
- 2020
-
In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 262
-
Journal article (peer-reviewed)abstract
- A one-step rapid pyrolysis activation method is proposed to produce activated coke powder (ACP) via a drop tube reactor by using pulverized Datong coal (DTC) and pine wood (PW) as feedstock. Small feedstock particle size, high heating rate, and effective activation agent, i.e., the mixture of oxygen and steam were arranged for the fast formation and development of various pore structure of ACPs. Detail characteristics of the ACP were investigated by using the nitrogen adsorption measurement, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) analysis. Results showed that the ACP presented well-developed nanostructure with considerable pore volume, specific surface area and surface functional groups. The pore volume and specific surface area of PWC-O6S10 could reach 0.2373 cm3/g and 250.57 m2/g. Activation atmosphere had played an important role to develop the pore structure and morphology of the ACP. Under 6 vol% oxygen concentration, the optimum steam partial pressure for micropore development of DTC was about 15 vol%, while it mostly promoted the growth of mesopores for PWC. All ACP samples presented variety of C/O/N containing surface functional groups, including OH, CH, CC, CO, CO, COC, CN, CN, etc., which remained relatively stable as the activation agents concentration changed.
|
|
| 12. |
- Johansson, Wanja, et al.
(author)
-
Full year assessment of small-scale biomass-fueled district heating system with waste heat recovery
- 2022
-
In: European Biomass Conference and Exhibition Proceedings. - : ETA-Florence Renewable Energies. ; , s. 696-698
-
Conference paper (peer-reviewed)abstract
- The use of biomass for district heating is a carbon neutral and efficient way to heat buildings. To ensure a sustainable use of the biomass, it is important to ensure a high thermal efficiency not only in combustion facilities of all sizes. In this paper, the thermal efficiency of a 3 MW combustion unit with recovery of waste flue gas energy has been evaluated, using process data from a full year. A decreased efficiency is observed at boiler loads below 1 MW, while the efficiency is more stable at higher load. The furnace and boiler efficiency are stable over different moisture contents of the fuel, while the efficiency including heat recovery is greatly enhanced at high moisture content. High return water temperature was linked to a decreased efficiency of the whole system due to decreased efficiency of the heat recovery unit.
|
|
| 13. |
- Johansson, Wanja, et al.
(author)
-
Module-based simulation model for prediction of convective and condensational heat recovery in a centrifugal wet scrubber
- 2023
-
In: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 219
-
Journal article (peer-reviewed)abstract
- Biomass combustion is a carbon–neutral method to generate heat and power and is integral to combating climate change. The wet scrubber is a promising device for recovering heat and reducing particle emissions from flue gas, under the driving force of new European Union legislation. Here, the heat recovery of a wet scrubber was investigated using process data and computer simulations. The process data showed that the scrubber could continuously recover heat corresponding to 10–20% of the energy input. The simulation model consists of two interlinked modules: Module 1 simulates droplet movement in the scrubber, while Module 2 uses the output of Module 1 to predict the heat recovery. The model was validated against process data, showing a mean error of 5.6%. Further optimization was based on the validated model by varying different process parameters, including nozzle position and moisture addition to the flue gas. Moisture addition was shown to be a feasible strategy for potentially increasing heat recovery by up to 3.3%. These results indicate that heat recovery in wet scrubbers is a feasible way to make particle removal cost effective in medium-scale combustion facilities, and that the developed simulation model can play an important role in optimizing these processes.
|
|
| 14. |
- Lin, Leteng, 1980-, et al.
(author)
-
An Extractive Numerical Method to Interpret Gas Analysis from Domestic Scale Pellets Burner
- 2009
-
In: Book of proceedings-Bioenergy 2009. - Jyväskylä : FINBIO publication 45. - 9789525135442 ; , s. 517-523
-
Conference paper (peer-reviewed)abstract
- The mathematical background to the gas analysis problem is that the measurement system introduces a time constant into the gas analysis values. This time constant is not only a simple delay of the signal but also involve a damping of the amplitudes in the signal. Therefore, the registered values by measurement system can be treated as the convolution between the system response and the real gas analysis values. In this paper the plug flow with an overlaid axial diffusion was introduced to simulate the delay and damping effects of gas measurement system. The numerical method developed here is to extract the real gas values from the measured data in the de-convolution way to find what the reality is behind the registered values. All registered data were collected by two different gas analysis systems for measuring the gas out of a pellets burner – Velmax (Finnish brand). This numerical method is meaningful to get closer to the reality of measured data which is definitely needed step for the improvement of controlling the small scale combustion even though it still can be developed further.
|
|
| 15. |
- Lin, Leteng, 1980-, et al.
(author)
-
High-temperature Kinetics of Fine Biomass Char Particles in Air and CO2
- 2010
-
In: 18th European Biomass Conference and Exhibition.
-
Conference paper (peer-reviewed)abstract
- Knowledge of reliable chemical kinetics of char always plays significant roles in the modelling, design and optimization of processes during biofuel thermochemical conversions.The determination of reaction kinetics of char in the high-temperature range still highly depends on the extrapolation of results from kinetic data determined at lower temperatures due to mass and heat transfer limitations. In this work an aerosol-based method was used to investigate the reactivity of singly-distributed char particles with aerodynamic diameters between 0.5-10 mm. The conversion of char particles in the reactor at varying temperatures and residence time was determined by comparing the particle size distributions before and after passing the reactor, using an aerodynamic particle sizer (APS) spectrometer. The results of char particles reacted with air, CO2 and steam indicate that the aerosol-based method can be used to determine reaction kinetics of char particles in the high temperature range where reaction is controlled by diffusion limitation if using conventional thermogravimetric analysis (TGA). By combining the aerosol-based method and conventional TGA, the oxidation and gasification kinetic parameters of biomass char can be derived in the temperature range of 350-800ºC, and 800-1200ºC respectively. The aerosol-based method shows the potential of on-line measuring the char reactivity.
|
|
| 16. |
- Lin, Leteng, 1980-, et al.
(author)
-
Investigation on the oxidation kinetics of biomass char particles
- 2009
-
In: Book of Proceeding-Bioenergy 2009. - Jyväskylä : FINBIO. - 9789525135442 ; , s. 933-939
-
Conference paper (peer-reviewed)abstract
- One specific type of wood pellets were pyrolyzed with both low and high heating rate in nitrogen atmosphere at 800-900°C. The pulverized chars were oxidized by thermo gravimetric analysis (TGA) in an atmosphere of nitrogen with 3%-21% of oxygen admixture. Three pore models reported in the literature were tested against the experimental data. In order to investigate the reactivity of singly distributed particles, char samples were fragmented and suspended into a gas using a shaking device. A fraction of suspended particles with an aerodynamic diameter between 0.5-10 um were then fed into a tubular reactor heated by an electric oven. The oxidation of char particles in the reactor at different temperatures was investigated by measuring the particle size distribution before and after passing the reactor, using an aerodynamic particle sizer (APS) spectrometer. This method made it possible to investigate the oxidation kinetics of char particles at high temperature area which is hard to realize in TGA due to the mass transportation limitation.
|
|
| 17. |
- Morgalla, Mario, 1987-, et al.
(author)
-
Benzene Conversion in a Packed Alumina Bed Continuously Fed with Woody Char Particles
- 2018
-
In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:7, s. 7670-7677
-
Journal article (peer-reviewed)abstract
- This Article investigates the decomposition of benzene (as a model tar) over finely dispersed char particles continuously distributed into a packed bed. Fragmented char particles and benzene plus a gasification agent (H2O or CO2) were supplied into a ceramic reactor that was heated electrically. The supplied char particles were retained in the reactor by a bed of alumina grains. Woody char as well as iron-doped and potassium-doped woody char were used. The influence of the gasification agent, char concentration, char weight time (proportional to the instant char mass present in the bed), and bed temperature (600-1050 degrees C) was investigated. Increasing the char concentration and char weight time increased benzene conversions for all tested chars. At similar char weight times, the benzene conversion increased with temperature, whereas the iron- and potassium doped char did not affect the specific conversion. At similar char concentrations, changing the gasification agent from CO2 to steam as well as using doped char led to decreased benzene conversions. This can be explained by accelerated char gasification reactions and thus a diminished char mass in the packed bed. Furthermore, benzene conversion rates were enhanced in the presence of CO2 as compared to steam. As the temperature was increased from 950 to 1050 degrees C, the benzene conversions were slightly reduced. This was interpreted as a combined effect of the enhanced benzene conversion rates and reduced char weight times. The highest benzene conversions achieved in the experiments were approximately 80% at 950-1000 degrees C using CO2 as gasification agent and supplying approximately 20-30 g N m(-3) undoped woody char.
|
|
| 18. |
- Morgalla, Mario, 1987-, et al.
(author)
-
Benzene conversion in a packed bed loaded with biomass char particles
- 2018
-
In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 32:1, s. 554-560
-
Journal article (peer-reviewed)abstract
- This study investigates the conversion of benzene in a packed bed containing fine char particles. Benzene and steam were simultaneously supplied to a tubular ceramic reactor that was heated electrically. Fragmented char particles were suspended and continuously supplied via a separate supply line. A packed bed of crushed alumina balls was positioned in the reactor to retain the char particles. The benzene conversion in the hot char bed was investigated by varying the bed temperature (900–1100 °C), steam concentration (0–27 vol %), and char concentration (5–50 g Nm–3). The highest conversions achieved in the experiments were approximately 75%. At comparable char concentrations, similar benzene conversions occurred at 900 and 1000 °C. Increasing the temperature to 1100 °C or increasing the steam concentration reduced the benzene conversion. The results indicate that the reduced conversion was due to enhanced char gasification reactions at elevated temperatures and steam concentrations and thus to reduced char mass in the packed bed.
|
|
| 19. |
- Pettersson, Jens, 1960-, et al.
(author)
-
Charging and removal efficiency of an ESP in a 250 kW biomass boiler
- 2012
-
In: International Journal of Plasma Environmental Science and Technology. - : The Institute of Electrostatics Japan. - 1881-8692 .- 2435-0125. ; 6:3, s. 204-209
-
Journal article (peer-reviewed)abstract
- The combustion of biomass creates ultra-fine particulate matter which is not precipitated by traditional multi cyclone technique, usually adopted on small scale plants. In Sweden the number of small bio fuelled plants is increasing and there is a need for cost effective means to precipitate the ultra-fine particles formed. One such technique may be electrostatic precipitation, but the economy of scale is a constraining factor for systems commercially available today. This paper describes field tests of a low cost electrostatic precipitator, ESP, including not only investigation of collection efficiency, but also measurement of charging effectiveness. The aim of the tests was to determine the potential for the low cost ESP design to form part of an electrostatic precipitation system for use on bio fuelled plants in the megawatt scale. The charges acquired by the particles have been measured using a low pressure cascade impactor, ELPI. Measurements of charges were carried out on particles escaping from the ESP. The results of the measurements of particle charges indicates that the method may correctly reflect the mean charge levels of particles of the different sizes usually found within the fine particle mode of flue gases from biomass combustion.
|
|
| 20. |
- Wang, Chaoqian, et al.
(author)
-
A stepwise microwave synergistic pyrolysis approach to produce sludge-based biochars : Feasibility study simulated by laboratory experiments
- 2020
-
In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 272, s. 1-10
-
Journal article (peer-reviewed)abstract
- A stepwise microwave synergistic pyrolysis (SMSP) approach is proposed as a new way to relieve disposal problems of the sewage sludge. Here the sludge is first pre-pyrolyzed by a conventional heating stage, and then rapidly pyrolyzed by a microwave-induced heating stage without any extra microwave absorbers or blending needed. Under simulated process pyrolysis conditions, the dried sludge, intermediate and final sludge-based biochar samples were prepared in the laboratory. Their chemical composition, microstructure and morphology, and leaching toxicity of heavy metals were carefully characterized and analyzed by various techniques such as proximate and ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy (SEM-EDX). Results showed that the pre-pyrolytic biochar can be rapidly heated up to 1100 °C within 5 min under microwave irradiation. The pre-pyrolytic stage increased the carbonization and ash enrichment degree of the sludge which itself acted as a good microwave absorber while achieving a quick temperature rise under microwave irradiation. The ash remaining ratio and the specific surface area of the biochar derived from the SMSP approach (labelled as SBC2) are increased by 6.46% and 16.17% respectively, compared with the conventional biochar sample (SBC1). And SBC2 still had diverse surface functional groups kept after SMSP. The residual ratios of Ni, Cu, Zn, Pb, Cr and Cd in SBC2 was more noticeable than in SBC1 but the leaching ratios quite the contrary. Vitrification is also well proved by the increment of quartz peak detected by XRD tests, and the formation of melted glassy spheres with elemental composition of Si, Ca, Al observed by SEM-EDX. It can favorably increase solidification level and decrease leaching toxicity of heavy metals in the SBC2. The feasibility of this proposed SMSP concept has been positively supported by our experimental results. The properties of the sludge-based biochar produced from the SMSP approach also show great potential to be utilized as precursors to produce various adsorbents.
|
|
| 21. |
- Zhang, Xiaorong, et al.
(author)
-
Review of chemical looping process for carbonaceous feedstock Conversion : Rational design of oxygen carriers
- 2022
-
In: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 325
-
Research review (peer-reviewed)abstract
- The chemical looping partial oxidation (CLPO) process as a technology of chemical looping process (CLP) is recognized as a potential strategy for the efficient and clean conversion of fuels into syngas/H2. Herein, in view of the importance of low-cost high-performance metal oxides as oxygen carriers (OCs) for this conversion, we systematically review the classification and CLPO applications of such OCs and discuss the improvement of OC reactivity and stability via the creation of metal–metal or metal–support synergism, the generation of oxygen vacancies, and the enhancement of deactivation resistance. Further, we present the results of theoretical and experimental characterizations probing ion diffusion and surface reactions to provide insights into the related reaction mechanisms and touch on the challenges and opportunities of developing metal oxides with excellent reactivity and long-term cycling stability in CLP. Thus, this review facilitates the design and performance regulation of OCs for future energy conversion systems.
|
|
