eddy bramer | University of Twente (original) (raw)
Papers by eddy bramer
Co-firing of biomass with coal in traditional coal-fired power plants represents is a low-cost op... more Co-firing of biomass with coal in traditional coal-fired power plants represents is a low-cost option for a fast introduction of renewable energy on a large scale. However there are some technical issues associated with biomass co-firing such as fuel flexibility of the plant, combustion efficiency impacts on the ash marketing, fouling of the boilers, etc. The combustion efficiency is highly affected by the physical combustion properties of the biomass and coal, and the residence time in the reactor. Many researchers have used drop tube furnace DTF to study the combustion efficiency of coal and biomass (torrefied biomass), as the main parameters like heating rate and working temperature are close to the actual furnace. In this paper, the detailed description of the setup and the preliminary experimental results with saw dust and coal combustion with air at different particle size, and residence times will be presented.
Industrial & Engineering Chemistry Research, 2004
A project is carried out to develop a process for tar elimination downstream of a gasifier making... more A project is carried out to develop a process for tar elimination downstream of a gasifier making use of cheap and active materials as catalysts. In the first stage of the project, screening of catalysts was carried out in a fixed-bed tubular reactor. The results of the fixed-bed experiments will be used in the design of the process. This paper presents a review of the various types of catalysts that have been used in several research works to reduce the tars in the producer gas derived from the biomass gasification process. The catalysts are divided into two classes according to their production method: minerals and synthetic catalysts. A summary of the review and recommendations for good catalyst candidates and future work are also provided. a n.i.) not indicated. Reprinted from Biomass and Bioenergy, 16, Hasler, P. and Nussbaumer, Gas Cleaning for IC Engine Applications from Fixed Bed Biomass Gasification. pp 385-395, copyright (2004), with permission from Elsevier.
Fuel, 2008
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
International Journal of Heat and Mass Transfer, 2004
The minimum gas speed for a heat exchanger (HE) at which particulate fouling is avoided is invest... more The minimum gas speed for a heat exchanger (HE) at which particulate fouling is avoided is investigated. Fouling experiments have been done with particles of different sizes and different materials running under different gas speeds. It is found that the smallest particles in the flow deposit first on the tubes of the HE at areas of minimum flow velocities. Then the large particles deposit and the fouling layer starts to build up. The fouling layer thickness and growth over the HE tube is influenced by the flow speed. As the flow speed in the HE increases, the thickness and the surface area of the fouling layer deposited over the heat exchanger tube are reduced. There is a limiting flow speed above which fouling is avoided. This limiting speed is related to the critical flow velocity required to roll a particle resting on a flat surface. To prevent fouling, the gas speed of a HE should be larger than the critical flow velocity that corresponds to the particle size most likely to stick on the heat exchanger tube.
6th International Conference on Contemporary Problems of Thermal Engineering, Sep 20, 2020
Flash pyrolysis is a promising route for thermochemical conversion of wood, agricultural waste o... more Flash pyrolysis is a promising route for thermochemical conversion of wood, agricultural waste or biomass in general, yielding a biooil that can be a potential substitute for transportation fuels. However, the biooil obtained from conventional flash pyrolysis has low quality and needs expensive upgradation before it can be used as a transportation fuel. Research on catalytic aftertreatment of the biooil has not shown any promising results because of fast deactivation of the catalyst. In this work, a novel approach is introduced for the production of high quality biooil where flash pyrolysis and catalysis are employed in a single stage. A bench scale unit of 1kg/hr feedstock capacity is built up where flash pyrolysis and catalytic upgrading are integrated in an entrained downflow reactor. Integrated catalytic flash pyrolysis of biomass offers the possibility to improve the quality and stability of the oil produced by insitu deoxygenation and cracking. The experiments perfo...
Energies, 2021
The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dol... more The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dolomite on fast pyrolysis vapor upgrading of beechwood was investigated using an analytical pyro probe-gas chromatography/mass spectrometry instrument (Py-GC/MS) at a temperature of 500 °C. Overall, this research showcased that these catalysts can deoxygenate biomass pyrolysis vapors into a mixture of intermediate compounds which have substantially lower oxygen content. The intermediate compounds are deemed to be suitable for downstream hydrodeoxygenation processes and it also means that hydrogen consumption will be reduced as a result of moderate in-situ deoxygenation. Among the support catalysts, the application of hydrotalcite yielded the best results with the formation of moderately deoxygenated compounds such as light phenols, mono-oxy ketones, light furans and hydrocarbons with a TIC area % of 7.5, 44.8, 9.8 and 9.8, respectively. In addition, acids were considerably reduced. Dolomit...
Fuel Processing Technology, 2021
Abstract The dual effect of dolomite as a CO2 sorbent and deoxygenation catalyst in fast pyrolysi... more Abstract The dual effect of dolomite as a CO2 sorbent and deoxygenation catalyst in fast pyrolysis of beechwood was investigated. Investigation was performed on a bench scale fluidized bed reactor at an pyrolysis temperature of 500 °C and at different WHSV. CO2 breakthrough curves and bio-oil samples were produced simultaneously. The results show that dolomite is both a feasible catalyst and a CO2 sorbent as it produced a moderately deoxygenated bio-oil and a CO2 free and H2 rich gas. Acids were eliminated, whereas the concentration of methylated phenols and methylated cyclopentanones were enhanced. These results were achieved when rapid carbonation stage was prevailing throughout the experimental run. An organic rich bio-oil with 9.46 wt% yield and a HHV of 28.0 MJ/kg (as received) was obtained. The pH of the catalytic bio-oil increased from 3.2 to 6.0 and the oxygen content reduced to 21.5 wt% from 47.3 wt%. Moreover, the moderately deoxygenated bio-oil is of interest as it can undergo downstream reforming into wide range of liquid fuels with reduced H2 consumption. Calculations show that the H2 generated as a result of CO2 sorption can suffice the requirement for hydrodeoxygenation. In addition the catalysts were also characterized by BET, XRD and SEM analysis.
Renewable Energy, 2021
Abstract Digestate is a nutrient-rich substance produced by anaerobic digestion that contains org... more Abstract Digestate is a nutrient-rich substance produced by anaerobic digestion that contains organic, inorganic, and biological matter. The European Nitrates Directive (91/676/EEC) provides regulations regarding the wider implementation of the digestate. Owing to a significant amount of organic matter in the digestate, it can be utilised as a solid biofuel, soil amendment substance, or substrate for activated carbon production. However, the solid by-products of the anaerobic digestion of the municipal solid waste wet fraction cannot be used for such applications because it is still considered a waste. Hydrothermal carbonisation (HTC) was investigated as a pre-treatment method for the digestate obtained by anaerobic digestion of the municipal solid waste wet fraction. HTC was carried out at temperatures of 180, 200 and 230 °C and residence times of 30, 60 and 120 min. The value of pressure was determined based on water temperature and partial pressure of the gaseous by-products. The HTC process resulted in changes in the physical and chemical properties of the hydrochars compared to those of the raw materials. A temperature of 200 °C and residence time of 60 min during HTC were optimal for energy consumption; this hydrochar exhibited the best combustion parameters and physical properties (specific surface area).
American Journal of Analytical Chemistry, 2017
Supercritical Water Gasification is an efficient technology in converting wet biomass into H 2 an... more Supercritical Water Gasification is an efficient technology in converting wet biomass into H 2 and CH 4 in comparison to other conventional thermochemical processes. Coke deposition, however, remains as a major challenge in this technology. Coke formation is the result of polymerization reactions that take place at sub-critical conditions. Directly injecting the relatively unheated wet biomass feed into supercritical water increases the heating rate and reduces the residence time of the feed in the sub-critical condition. This leads to a minimized coke formation in the process. However, a non-isothermal mixing takes place during this direct injection that is less energy-efficient. In addition, the biomass feedstream experiences less pre-heating that means less heat recovery from the product gas. These two aspects might reduce the overall process performance. Parametric studies of key operating parameters, such as operating temperature, dry matter content, bypass water ratio and heat exchanger effectiveness, are carried out to investigate the influence of direct injection to the thermal efficiency of the system. Subsequently, optimization using pinch analysis is conducted to the system with direct injection. Finally, an operating window for optimum performance of the optimized direct injection gasification system is proposed.
Energies, 2021
New regulations aimed at curbing the problem of eutrophication introduce limitations for traditio... more New regulations aimed at curbing the problem of eutrophication introduce limitations for traditional ways to use the by-product of anaerobic digestion—the digestate. Hydrothermal carbonisation (HTC) can be a viable way to valorise the digestate in an energy-efficient manner and at the same time maximise the synergy in terms of recovery of water, nutrients, followed by more efficient use of the remaining carbon. Additionally, hydrothermal treatment is a feasible way to recirculate recalcitrant process residues. Recirculation to anaerobic digestion enables recovery of a significant part of chemical energy lost in HTC by organics dissolved in the liquid effluent. Recirculating back to the HTC process can enhance nutrient recovery by making process water more acidic. However, such an effect of synergy can be exploited to its full extent only when viable separation techniques are applied to separate organic by-products of HTC and water. The results presented in this study show that using...
Journal of Energy Resources Technology, 2020
Currently, the reclamation and reuse of water have not reached their full potential, although mor... more Currently, the reclamation and reuse of water have not reached their full potential, although more energy is needed to obtain and transport freshwater and this solution has a more serious environmental impact. Agricultural irrigation is, by far, the largest application of reclaimed water worldwide, so the proposed concept may result in the production of water that can be used, among others, for crop irrigation. This paper describes a novel installation for the recovery of the agricultural water from the digestate, along with the results of initial experiments. Currently, water is wasted, due to evaporation, in anaerobic digestion plants, as the effluent from dewatering of the digestate is discharged into lagoons. Moreover, water that stays within the interstitial space of the digestate is lost in a similar fashion. With increasing scarcity of water in rural areas, such waste should not be neglected. The study indicates that hydrothermal carbonization (HTC) enhances mechanical dewate...
The Journal of Supercritical Fluids, 2018
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 2 Model provides good match for char yield, with 13% difference from experimental results Instantaneous heating of biomass plays a major role in reducing char that is produced Scaling up the reactor size close to a pilot scale increases the char yield by 87 %
Chemical Engineering Science, 2018
h i g h l i g h t s Na 2 CO 3 loaded over activated carbon honeycombs made cheap and non-hazardou... more h i g h l i g h t s Na 2 CO 3 loaded over activated carbon honeycombs made cheap and non-hazardous adsorbents. CO 2 capture occurred in ranges of temperature and humidity representative of ambient air. CO 2 requirements in closed greenhouses could be fulfilled, replacing fossil fuels.
Industrial & Engineering Chemistry Research, 2018
Potassium carbonate is a highly hygroscopic salt, and this aspect becomes important for CO 2 capt... more Potassium carbonate is a highly hygroscopic salt, and this aspect becomes important for CO 2 capture from ambient air. Moreover, CO 2 capture from ambient air requires adsorbents with a very low pressure drop. In the present work an activated carbon honeycomb monolith was coated with K 2 CO 3 , and it was treated with moist N 2 to hydrate it. Its CO 2 capture capacity was studied as a function of the temperature, the water content of the air, and the air flow rate, following a factorial design of experiments. It was found that the water vapor content in the air had the largest influence on the CO 2 adsorption capacity. Moreover, the deliquescent character of K 2 CO 3 led to the formation of an aqueous solution in the pores of the carrier, which regulated the temperature of the CO 2 adsorption. The transition between the anhydrous and the hydrated forms of potassium carbonate was studied by means of FT-IR spectroscopy. It can be concluded that hydrated potassium carbonate is a promising and cheap alternative for CO 2 capture from ambient air for the production of CO 2-enriched air or for the synthesis of solar fuels, such as methanol.
Energies, 2016
Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrad... more Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liquid yield due to the increased production of non-condensables, primarily hydrocarbons. The catalytically produced bio-oil was less viscous and zeolites were effective at cracking heavy molecular weight compounds in the bio-oil. Acidic zeolites, H-Y and H-ZSM5, increased the desirable chemical compounds in the bio-oil such as phenols, furans and hydrocarbon, and reduced the undesired compounds such as acids. On the other hand reducing the acidity of zeolites reduced some of the undesired compounds in the bio-oil such as ketones and aldehydes. The performance of H-Y was superior to that of the rest of zeolites studied: bio-oil of high chemical and calorific value was produced with a high organic liquid yield and low oxygen content. H-ZSM5 was a close competitor to H-Y in performance but with a lower yield of bio-oil. Online fractionation of catalytic pyrolysis vapors was employed by controlling the condenser temperature and proved to be a successful process parameter to tailor the desired bio-oil properties. A high calorific value bio-oil having up to 90% organics was produced using two staged condensation of catalytic pyrolysis vapor. Zeolite-based acidic catalysts can be used for selective deoxygenation, and the catalytic bio-oil quality can be further improved with staged vapor condensation.
Most widely used concept for municipal solid waste (MSW) incineration is combustion on a moving g... more Most widely used concept for municipal solid waste (MSW) incineration is combustion on a moving grate with energy recovery. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Ignition front propagates downwards producing heat for drying and devolatilisation of the fresh waste below until it reaches the grate. The present project is investigating the so called reversed combustion of waste on a grate. In this new concept the fuel layer is ignited by means of preheated air from below without any external ignition source. As a result a combustion front will be formed close to the grate and will propagate upwards. In order to investigate reversed combustion an experimental set-up that is able to simulate a real moving grate furnace is designed. Experimental study was conducted to determine the influence of different factors (amount of primary air, fuel moisture content etc.) on process parameters. In this paper, the detailed description of setup, as well as the results from experiments will be presented.
A new spiral reactor was designed to study visually the combustion characteristics of solid fuel.... more A new spiral reactor was designed to study visually the combustion characteristics of solid fuel. The ignition and combustion time of torrefied biomass was investigated under different temperature in O2/N2 and O2/CO2 atmosphere . High speed camera was used to determine the ignition and combustion time of the fuel. The ignition and combustion time decreases as the reactor temperature increases. Statistically describing, ignition time has lower standard deviation than combustion time as the former is mainly depend on the gas temperature and the availability of oxygen around. At lower temperatures between 500-600 C sudden decrease in ignition time was shown, which was the lowest temperature where ignition commences . Finally, changing the gas composition from O2/N2 and O2/CO2 (both 21% O2) showed increase in ignition time as the CO2 has high heat capacity which lowers the temperature round the particle.
Co-firing of biomass with coal in traditional coal-fired power plants represents is a low-cost op... more Co-firing of biomass with coal in traditional coal-fired power plants represents is a low-cost option for a fast introduction of renewable energy on a large scale. However there are some technical issues associated with biomass co-firing such as fuel flexibility of the plant, combustion efficiency impacts on the ash marketing, fouling of the boilers, etc. The combustion efficiency is highly affected by the physical combustion properties of the biomass and coal, and the residence time in the reactor. Many researchers have used drop tube furnace DTF to study the combustion efficiency of coal and biomass (torrefied biomass), as the main parameters like heating rate and working temperature are close to the actual furnace. In this paper, the detailed description of the setup and the preliminary experimental results with saw dust and coal combustion with air at different particle size, and residence times will be presented.
Industrial & Engineering Chemistry Research, 2004
A project is carried out to develop a process for tar elimination downstream of a gasifier making... more A project is carried out to develop a process for tar elimination downstream of a gasifier making use of cheap and active materials as catalysts. In the first stage of the project, screening of catalysts was carried out in a fixed-bed tubular reactor. The results of the fixed-bed experiments will be used in the design of the process. This paper presents a review of the various types of catalysts that have been used in several research works to reduce the tars in the producer gas derived from the biomass gasification process. The catalysts are divided into two classes according to their production method: minerals and synthetic catalysts. A summary of the review and recommendations for good catalyst candidates and future work are also provided. a n.i.) not indicated. Reprinted from Biomass and Bioenergy, 16, Hasler, P. and Nussbaumer, Gas Cleaning for IC Engine Applications from Fixed Bed Biomass Gasification. pp 385-395, copyright (2004), with permission from Elsevier.
Fuel, 2008
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
International Journal of Heat and Mass Transfer, 2004
The minimum gas speed for a heat exchanger (HE) at which particulate fouling is avoided is invest... more The minimum gas speed for a heat exchanger (HE) at which particulate fouling is avoided is investigated. Fouling experiments have been done with particles of different sizes and different materials running under different gas speeds. It is found that the smallest particles in the flow deposit first on the tubes of the HE at areas of minimum flow velocities. Then the large particles deposit and the fouling layer starts to build up. The fouling layer thickness and growth over the HE tube is influenced by the flow speed. As the flow speed in the HE increases, the thickness and the surface area of the fouling layer deposited over the heat exchanger tube are reduced. There is a limiting flow speed above which fouling is avoided. This limiting speed is related to the critical flow velocity required to roll a particle resting on a flat surface. To prevent fouling, the gas speed of a HE should be larger than the critical flow velocity that corresponds to the particle size most likely to stick on the heat exchanger tube.
6th International Conference on Contemporary Problems of Thermal Engineering, Sep 20, 2020
Flash pyrolysis is a promising route for thermochemical conversion of wood, agricultural waste o... more Flash pyrolysis is a promising route for thermochemical conversion of wood, agricultural waste or biomass in general, yielding a biooil that can be a potential substitute for transportation fuels. However, the biooil obtained from conventional flash pyrolysis has low quality and needs expensive upgradation before it can be used as a transportation fuel. Research on catalytic aftertreatment of the biooil has not shown any promising results because of fast deactivation of the catalyst. In this work, a novel approach is introduced for the production of high quality biooil where flash pyrolysis and catalysis are employed in a single stage. A bench scale unit of 1kg/hr feedstock capacity is built up where flash pyrolysis and catalytic upgrading are integrated in an entrained downflow reactor. Integrated catalytic flash pyrolysis of biomass offers the possibility to improve the quality and stability of the oil produced by insitu deoxygenation and cracking. The experiments perfo...
Energies, 2021
The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dol... more The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dolomite on fast pyrolysis vapor upgrading of beechwood was investigated using an analytical pyro probe-gas chromatography/mass spectrometry instrument (Py-GC/MS) at a temperature of 500 °C. Overall, this research showcased that these catalysts can deoxygenate biomass pyrolysis vapors into a mixture of intermediate compounds which have substantially lower oxygen content. The intermediate compounds are deemed to be suitable for downstream hydrodeoxygenation processes and it also means that hydrogen consumption will be reduced as a result of moderate in-situ deoxygenation. Among the support catalysts, the application of hydrotalcite yielded the best results with the formation of moderately deoxygenated compounds such as light phenols, mono-oxy ketones, light furans and hydrocarbons with a TIC area % of 7.5, 44.8, 9.8 and 9.8, respectively. In addition, acids were considerably reduced. Dolomit...
Fuel Processing Technology, 2021
Abstract The dual effect of dolomite as a CO2 sorbent and deoxygenation catalyst in fast pyrolysi... more Abstract The dual effect of dolomite as a CO2 sorbent and deoxygenation catalyst in fast pyrolysis of beechwood was investigated. Investigation was performed on a bench scale fluidized bed reactor at an pyrolysis temperature of 500 °C and at different WHSV. CO2 breakthrough curves and bio-oil samples were produced simultaneously. The results show that dolomite is both a feasible catalyst and a CO2 sorbent as it produced a moderately deoxygenated bio-oil and a CO2 free and H2 rich gas. Acids were eliminated, whereas the concentration of methylated phenols and methylated cyclopentanones were enhanced. These results were achieved when rapid carbonation stage was prevailing throughout the experimental run. An organic rich bio-oil with 9.46 wt% yield and a HHV of 28.0 MJ/kg (as received) was obtained. The pH of the catalytic bio-oil increased from 3.2 to 6.0 and the oxygen content reduced to 21.5 wt% from 47.3 wt%. Moreover, the moderately deoxygenated bio-oil is of interest as it can undergo downstream reforming into wide range of liquid fuels with reduced H2 consumption. Calculations show that the H2 generated as a result of CO2 sorption can suffice the requirement for hydrodeoxygenation. In addition the catalysts were also characterized by BET, XRD and SEM analysis.
Renewable Energy, 2021
Abstract Digestate is a nutrient-rich substance produced by anaerobic digestion that contains org... more Abstract Digestate is a nutrient-rich substance produced by anaerobic digestion that contains organic, inorganic, and biological matter. The European Nitrates Directive (91/676/EEC) provides regulations regarding the wider implementation of the digestate. Owing to a significant amount of organic matter in the digestate, it can be utilised as a solid biofuel, soil amendment substance, or substrate for activated carbon production. However, the solid by-products of the anaerobic digestion of the municipal solid waste wet fraction cannot be used for such applications because it is still considered a waste. Hydrothermal carbonisation (HTC) was investigated as a pre-treatment method for the digestate obtained by anaerobic digestion of the municipal solid waste wet fraction. HTC was carried out at temperatures of 180, 200 and 230 °C and residence times of 30, 60 and 120 min. The value of pressure was determined based on water temperature and partial pressure of the gaseous by-products. The HTC process resulted in changes in the physical and chemical properties of the hydrochars compared to those of the raw materials. A temperature of 200 °C and residence time of 60 min during HTC were optimal for energy consumption; this hydrochar exhibited the best combustion parameters and physical properties (specific surface area).
American Journal of Analytical Chemistry, 2017
Supercritical Water Gasification is an efficient technology in converting wet biomass into H 2 an... more Supercritical Water Gasification is an efficient technology in converting wet biomass into H 2 and CH 4 in comparison to other conventional thermochemical processes. Coke deposition, however, remains as a major challenge in this technology. Coke formation is the result of polymerization reactions that take place at sub-critical conditions. Directly injecting the relatively unheated wet biomass feed into supercritical water increases the heating rate and reduces the residence time of the feed in the sub-critical condition. This leads to a minimized coke formation in the process. However, a non-isothermal mixing takes place during this direct injection that is less energy-efficient. In addition, the biomass feedstream experiences less pre-heating that means less heat recovery from the product gas. These two aspects might reduce the overall process performance. Parametric studies of key operating parameters, such as operating temperature, dry matter content, bypass water ratio and heat exchanger effectiveness, are carried out to investigate the influence of direct injection to the thermal efficiency of the system. Subsequently, optimization using pinch analysis is conducted to the system with direct injection. Finally, an operating window for optimum performance of the optimized direct injection gasification system is proposed.
Energies, 2021
New regulations aimed at curbing the problem of eutrophication introduce limitations for traditio... more New regulations aimed at curbing the problem of eutrophication introduce limitations for traditional ways to use the by-product of anaerobic digestion—the digestate. Hydrothermal carbonisation (HTC) can be a viable way to valorise the digestate in an energy-efficient manner and at the same time maximise the synergy in terms of recovery of water, nutrients, followed by more efficient use of the remaining carbon. Additionally, hydrothermal treatment is a feasible way to recirculate recalcitrant process residues. Recirculation to anaerobic digestion enables recovery of a significant part of chemical energy lost in HTC by organics dissolved in the liquid effluent. Recirculating back to the HTC process can enhance nutrient recovery by making process water more acidic. However, such an effect of synergy can be exploited to its full extent only when viable separation techniques are applied to separate organic by-products of HTC and water. The results presented in this study show that using...
Journal of Energy Resources Technology, 2020
Currently, the reclamation and reuse of water have not reached their full potential, although mor... more Currently, the reclamation and reuse of water have not reached their full potential, although more energy is needed to obtain and transport freshwater and this solution has a more serious environmental impact. Agricultural irrigation is, by far, the largest application of reclaimed water worldwide, so the proposed concept may result in the production of water that can be used, among others, for crop irrigation. This paper describes a novel installation for the recovery of the agricultural water from the digestate, along with the results of initial experiments. Currently, water is wasted, due to evaporation, in anaerobic digestion plants, as the effluent from dewatering of the digestate is discharged into lagoons. Moreover, water that stays within the interstitial space of the digestate is lost in a similar fashion. With increasing scarcity of water in rural areas, such waste should not be neglected. The study indicates that hydrothermal carbonization (HTC) enhances mechanical dewate...
The Journal of Supercritical Fluids, 2018
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service... more This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 2 Model provides good match for char yield, with 13% difference from experimental results Instantaneous heating of biomass plays a major role in reducing char that is produced Scaling up the reactor size close to a pilot scale increases the char yield by 87 %
Chemical Engineering Science, 2018
h i g h l i g h t s Na 2 CO 3 loaded over activated carbon honeycombs made cheap and non-hazardou... more h i g h l i g h t s Na 2 CO 3 loaded over activated carbon honeycombs made cheap and non-hazardous adsorbents. CO 2 capture occurred in ranges of temperature and humidity representative of ambient air. CO 2 requirements in closed greenhouses could be fulfilled, replacing fossil fuels.
Industrial & Engineering Chemistry Research, 2018
Potassium carbonate is a highly hygroscopic salt, and this aspect becomes important for CO 2 capt... more Potassium carbonate is a highly hygroscopic salt, and this aspect becomes important for CO 2 capture from ambient air. Moreover, CO 2 capture from ambient air requires adsorbents with a very low pressure drop. In the present work an activated carbon honeycomb monolith was coated with K 2 CO 3 , and it was treated with moist N 2 to hydrate it. Its CO 2 capture capacity was studied as a function of the temperature, the water content of the air, and the air flow rate, following a factorial design of experiments. It was found that the water vapor content in the air had the largest influence on the CO 2 adsorption capacity. Moreover, the deliquescent character of K 2 CO 3 led to the formation of an aqueous solution in the pores of the carrier, which regulated the temperature of the CO 2 adsorption. The transition between the anhydrous and the hydrated forms of potassium carbonate was studied by means of FT-IR spectroscopy. It can be concluded that hydrated potassium carbonate is a promising and cheap alternative for CO 2 capture from ambient air for the production of CO 2-enriched air or for the synthesis of solar fuels, such as methanol.
Energies, 2016
Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrad... more Bio-oil produced from conventional flash pyrolysis has poor quality and requires expensive upgrading before it can be used as a transportation fuel. In this work, a high quality bio-oil has been produced using a novel approach where flash pyrolysis, catalysis and fractionation of pyrolysis vapors using two stage condensation are combined in a single process unit. A bench scale unit of 1 kg/h feedstock capacity is used for catalytic pyrolysis in an entrained down-flow reactor system equipped with two-staged condensation of the pyrolysis vapor. Zeolite-based catalysts are investigated to study the effect of varying acidities of faujasite Y zeolites, zeolite structures (ZSM5), different catalyst to biomass ratios and different catalytic pyrolysis temperatures. Low catalyst/biomass ratios did not show any significant improvements in the bio-oil quality, while high catalyst/biomass ratios showed an effective deoxygenation of the bio-oil. The application of zeolites decreased the organic liquid yield due to the increased production of non-condensables, primarily hydrocarbons. The catalytically produced bio-oil was less viscous and zeolites were effective at cracking heavy molecular weight compounds in the bio-oil. Acidic zeolites, H-Y and H-ZSM5, increased the desirable chemical compounds in the bio-oil such as phenols, furans and hydrocarbon, and reduced the undesired compounds such as acids. On the other hand reducing the acidity of zeolites reduced some of the undesired compounds in the bio-oil such as ketones and aldehydes. The performance of H-Y was superior to that of the rest of zeolites studied: bio-oil of high chemical and calorific value was produced with a high organic liquid yield and low oxygen content. H-ZSM5 was a close competitor to H-Y in performance but with a lower yield of bio-oil. Online fractionation of catalytic pyrolysis vapors was employed by controlling the condenser temperature and proved to be a successful process parameter to tailor the desired bio-oil properties. A high calorific value bio-oil having up to 90% organics was produced using two staged condensation of catalytic pyrolysis vapor. Zeolite-based acidic catalysts can be used for selective deoxygenation, and the catalytic bio-oil quality can be further improved with staged vapor condensation.
Most widely used concept for municipal solid waste (MSW) incineration is combustion on a moving g... more Most widely used concept for municipal solid waste (MSW) incineration is combustion on a moving grate with energy recovery. In MSW incinerators fresh waste stacked on a grate enters the combustion chamber, heats up by radiation from the flame above the layer and ignition occurs. Ignition front propagates downwards producing heat for drying and devolatilisation of the fresh waste below until it reaches the grate. The present project is investigating the so called reversed combustion of waste on a grate. In this new concept the fuel layer is ignited by means of preheated air from below without any external ignition source. As a result a combustion front will be formed close to the grate and will propagate upwards. In order to investigate reversed combustion an experimental set-up that is able to simulate a real moving grate furnace is designed. Experimental study was conducted to determine the influence of different factors (amount of primary air, fuel moisture content etc.) on process parameters. In this paper, the detailed description of setup, as well as the results from experiments will be presented.
A new spiral reactor was designed to study visually the combustion characteristics of solid fuel.... more A new spiral reactor was designed to study visually the combustion characteristics of solid fuel. The ignition and combustion time of torrefied biomass was investigated under different temperature in O2/N2 and O2/CO2 atmosphere . High speed camera was used to determine the ignition and combustion time of the fuel. The ignition and combustion time decreases as the reactor temperature increases. Statistically describing, ignition time has lower standard deviation than combustion time as the former is mainly depend on the gas temperature and the availability of oxygen around. At lower temperatures between 500-600 C sudden decrease in ignition time was shown, which was the lowest temperature where ignition commences . Finally, changing the gas composition from O2/N2 and O2/CO2 (both 21% O2) showed increase in ignition time as the CO2 has high heat capacity which lowers the temperature round the particle.