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Sökning: WFRF:(Rydén Magnus 1975)

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1.
  • Aronsson, Jesper, et al. (författare)
  • Increasing gas-solids mass transfer in fluidized beds by application of confined fluidization-A feasibility study
  • 2019
  • Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 9:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Fluidized bed applications where the bed material plays an active role in chemical reactions, e.g. chemical looping combustion, have seen an increase in interest over the past decade. When these processes are to be scaled up to industrial or utility scale mass transfer between the gas and solids phases can become a limitation for conversion. Confined fluidized beds were conceptualized for other purposes in the 1960's but are yet to be applied to these recent technologies. Here it is investigated if they can prove useful to increase mass transfer but also if they are feasible from other perspectives such as pressure drop increase and solids throughflow. Four spherical packing solids, 6.35-25.4 mm in diameter at two different densities, were tested. For mass transfer experiments the fluidizing air was humidified and the water adsorption rate onto silica gel particles acting as fluidizing solids was measured. Olivine sand was used in further experiments measuring segregation of solids and packing, and maximum vertical crossflow of solids. It was found that mass transfer increased by a factor of 1.9-3.8 with packing solids as compared to a non-packed reference. With high-density packing, fluidizing solids voidage inside the packing was found to be up to 58% higher than in a conventional fluidized bed. Low density packing material favoured its flotsam segregation and with it higher fluidization velocities yield better mixing between packing and fluidizing solids. Maximum vertical cross-flow was found to be significantly higher with low density packing that fluidized, than with stationary high-density packing. Conclusively, the prospect of using confined fluidized beds for improving mass transfer looks promising from both performance and practical standpoints.
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2.
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3.
  • Nemati, Nasrin, 1988, et al. (författare)
  • Experimental Investigation and Modeling of the Impact of Random Packings on Mass Transfer in Fluidized Beds
  • 2024
  • Ingår i: Powder Technology. - 1873-328X .- 0032-5910. ; 440
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigates the impact of two novel settings of bubbling fluidized beds equipped with random metal packings on the mass transfer. To do this, a comprehensive approach is applied that integrates experiments and modeling and explores the relevance of the different underlying mechanisms involved in interphase mass transfer in fluidized beds. Firstly, the mass transfer of water from moisturized silica gel particles to dry air is studied in both a packed-fluidized bed and a freely bubbling bed with no packing. The experimental set-up consists of a cylindrical bubbling fluidized-bed column with an inner diameter of 22 cm. Silica-gel particles with a mean particle diameter of 797 µm are used as bed material. The total bed amount ranges from 4 to 8 kg, while the fluidization number (F) varies between 1.7 and 2.3. Two types of packing, RMSR (stainless steel thread saddle rings) and Hiflow (stainless steel pall rings) are examined and compared to the reference case of a bubbling bed with no packing. The height of the packed section is maintained at 60 cm. The results show that, at all operating conditions, the use of packings enhances the amount of desorbed water in the fluidized bed. The increase is up to 17%, as compared to the bed without packing. The effect is believed to be inhibition of bubble growth in the packed-fluidized bed. To study this further, a mass-transfer model is introduced to analyze the different mass-transfer steps (intra-particle, particle surface to emulsion gas, and emulsion gas to bubble gas) in packed-fluidized beds compared to beds with no packing. TGA experiments are applied to describe the intra-particle mass transfer through a desorption kinetic model. Model analysis shows that the main resistance for mass transfer occurs across the bubble-emulsion boundary. The calculated value of the mass transfer coefficient for this, Kb, at reference conditions (6 kg of silica gel and F=2.3) is 7.6e-5 s-1 with packings (in average) and 6.2e-5 s-1 without packings, i.e. a 23% improvement in the governing mass-transfer coefficient.
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4.
  • Rydén, Magnus, 1975, et al. (författare)
  • Fe2O3 on Ce-, Ca- or Mg-stabilized ZrO2 as oxygen carrier for chemical-looping combustion using NiO as additive
  • 2010
  • Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 56:8, s. 2211-2220
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen-carrier particles for chemical-looping combustion have been manufactured by freeze granulation. The particles consisted of 60 wt % Fe2O3 as active phase and 40 wt % stabilized ZrO2 as support material. Ce, Ca, or Mg was used to stabilize the ZrO2. The hardness and porosity of the particles were altered by varying the sintering temperature. The oxygen carriers were examined by redox experiments in a batch fluidized- bed reactor at 800–950°C, using CH4 as fuel. The experiments showed good reactivity between the particles and CH4. NiO was used as an additive and was found to reduce the fraction of unconverted CH4 with up to 80%. The combustion efficiency was 95.9% at best and was achieved using 57 kg oxygen carrier per MW fuel. Most produced oxygen carriers appear to have been decently stable, but using Ca as stabilizer resulting in uneven results. Further, particles sintered at high temperatures had a tendency to defluidize.
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5.
  • Rydén, Magnus, 1975, et al. (författare)
  • Ilmenite with addition of NiO as oxygen carrier for chemical-looping combustion
  • 2010
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 89:11, s. 3523-3533
  • Tidskriftsartikel (refereegranskat)abstract
    • The naturally occurring mineral ilmenite, FeTiO3, has been examined as oxygen carrier for chemical-loopingcombustion. NiO-based particles have been used as an additive, in order to examine if it is possible toutilize the catalytic properties of metallic Ni to facilitate decomposition of hydrocarbons into more reactivecombustion intermediates such as CO and H2. Firstly, ilmenite was examined by oxidation and reductionexperiments in a batch fluidized-bed reactor. These experiments indicated moderate reactivitybetween ilmenite and CH4, which was used as reducing gas. However, adding 5 wt.% of NiO-based particlesto the ilmenite improved the conversion of CH4 greatly, resulting in an increase in combustion efficiencywith a factor of 3. Secondly, 83 h of chemical-looping combustion experiments were conducted ina small circulating fluidized-bed reactor, using ilmenite as oxygen carrier and natural gas as fuel. A widerange of process parameters and different levels of NiO addition were examined. Occasionally, there wereproblems with the circulation of solids between the air reactor and fuel reactor, but most of the time theexperiments worked well. The products were mostly CO2, H2O and unconverted CH4. Adding smallamounts of NiO-based particles to the reactor increased the conversion of the fuel considerably. Forthe base case conducted at 900, the combustion efficiency was 76% for pure ilmenite and 90% for thecorresponding experiments with 1 wt.% NiO-based particles added to the reactor. The properties ofilmenite were found to change considerably during operation. Used particles had lower density, weremore reactive and more porous than fresh particles. These changes appear to have been physical, andno unexpected chemical phases could be identified.
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6.
  • Rydén, Magnus, 1975, et al. (författare)
  • NiO supported on Mg-ZrO2 as oxygen carrier for chemical-looping combustion and chemical-looping reforming
  • 2009
  • Ingår i: Energy and Environmental Sciences. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 2:9, s. 970-981
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen-carrier particles consisting of 40 wt% NiO supported on 60 wt% Mg-stabilized ZrO2 were produced by freeze granulation and examined as oxygen carrier for chemical-looping applications. Firstly, the particles were examined by oxidation and reduction experiments in a batch fluidized-bed reactor. These experiments indicated very high reactivity with CH4 and low affinity for carbon formation. For highly oxidized particles the products were CO2 and H2O, while for reduced particles they were CO and H2. Secondly, the particles were examined by 40 hours of operation in a small circulating fluidized-bed reactor, using natural gas as fuel. For chemical-looping combustion, there was complete conversion of fuel into products with high selectivity towards CO2 and H2O. At 950ºC, a combustion efficiency of 99.3% was achieved, which is only 0.1%-point below the theoretical maximum, i.e. thermodynamic equilibrium. For chemical-looping reforming, the conversion of fuel was 99.9% or higher, with high selectivity towards CO and H2. Operating at the desired process parameters, which was a fuel reactor temperature of 950ºC and an air ratio of 0.30, worked flawlessly. When only natural gas was used as fuel there was slight formation of solid carbon in the fuel reactor. Adding 30 vol% steam to the fuel removed the carbon formation. The particles retained their physical and chemical structure reasonably well during operation. Approximately 5% of the particles added to the reactor were lost as fines during the first hours of operation. Further, the porosity of the particles increased somewhat during operation. The density was 10% lower for used particles, compared to fresh.
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8.
  • Arjmand, Mehdi, 1986, et al. (författare)
  • CaxLa1−xMn1−yMyO3−δ (M = Mg, Ti, Fe or Cu) as Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU)
  • 2013
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:8, s. 4097-4107
  • Tidskriftsartikel (refereegranskat)abstract
    • Perovskite materials of the type CaxLa1−xMn1−yMyO3−δ (M = Mg, Ti, Fe or Cu) have been investigated as oxygen carriers for the chemical-looping with oxygen uncoupling (CLOU) process. The oxygen carrier particles were produced by mechanical homogenization of primary solids in a rotary evaporator followed by extrusion and calcination at 1300°C for 6 h. The chemical-looping characteristics of the substituted perovskites developed in this work were evaluated in a laboratory-scale fluidized-bed reactor in the temperature range of 900−1000°C during alternating reducing and oxidizing conditions. The oxygen carriers showed oxygen releasing behaviour (CLOU) in inert atmosphere between 900−1000°C. In addition, their reactivity with methane was high, approaching complete gas yield for all of the materials at 950°C, the exception being the Cu-doped perovskite which defluidized during reduction. The rates of oxygen release were also investigated using devolatilized wood char as solid fuel, and were found to be similar. The required solids inventory in the fuel reactor for the perovskite oxygen carriers is estimated to be 325 kg/MWth. All of the formulations exhibited high rates of oxidation and high degree of stability with no particle fragmentation or agglomeration. The high reactivity and favourable oxygen uncoupling properties make these oxygen carriers promising candidates for the CLOU process.
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9.
  • Arjmand, Mehdi, 1986, et al. (författare)
  • CaZrO3 and SrZrO3-based CuO Oxygen Carriers for Chemical-Looping with Oxygen Uncoupling (CLOU)
  • 2014
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 51, s. 75-84
  • Konferensbidrag (refereegranskat)abstract
    • The chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) processes are novel solutions for efficient combustion with inherent separation of carbon dioxide. In this work, oxygen carriers based on CuO supported by zirconates of SrZrO3 and CaZrO3 are investigated. The oxygen carriers were produced by mechanical homogenization of primary solids in a rotary evaporator followed by extrusion, drying and calcination at 950 and 1030 degrees C for 6 h. Their chemical-looping performance was evaluated in a laboratory-scale fluidized-bed reactor at 900 and 925 degrees C under cyclic oxidizing, inert (N-2) and reducing (CH4) conditions. All oxygen carriers exhibited rapid release of oxygen in the inert environment (CLOU) with high conversion of methane. The carrier calcined at 1030 degrees C with SrZrO3 as support showed no agglomeration or deactivation and exhibited the highest reactivity. Thus, the use of this oxygen carrier could be of interest for the CLOU process.
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10.
  • Arjmand, Mehdi, 1986, et al. (författare)
  • Screening of Combined Mn-Fe-Si Oxygen Carriers for Chemical Looping with Oxygen Uncoupling (CLOU)
  • 2015
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 29:3, s. 1868-1880
  • Tidskriftsartikel (refereegranskat)abstract
    • Combined oxygen carriers of Mn, Fe, and Si were screened for the chemical looping with oxygen uncoupling process with the objective of identifying materials with high reactivity and sufficient attrition resistance. Eleven oxygen carrier materials were produced by spray-drying and then calcined for 4 h at 1100 and 1200 degrees C. The ability of the oxygen carriers to release oxygen and to convert gaseous fuels was investigated in a batch fluidized-bed reactor under alternating reducing and oxidizing conditions for temperatures ranging from 850 degrees C to 1050 degrees C. The attrition behavior of the different materials was evaluated in a jet-cup attrition rig. All investigated oxygen carriers proved to release oxygen and showed high reactivity toward synthesis gas (50% CO in H-2). Oxygen carrier materials with comparably lower mechanical stability were found to have a higher reactivity toward methane. One of the investigated formulations showed to have both high mechanical stability and resistance toward attrition, as well as good methane conversion and oxygen release.
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11.
  • Arjmand, Mehdi, 1986, et al. (författare)
  • Sulfur Tolerance and Rate of Oxygen Release of Combined Mn-Si Oxygen Carriers in Chemical-Looping with Oxygen Uncoupling (CLOU)
  • 2014
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:50, s. 19488-19497
  • Tidskriftsartikel (refereegranskat)abstract
    • Sulfur tolerance and rate of oxygen release of combined Mn-Si oxygen carriers for chemical-looping with oxygen uncoupling (CLOU) is investigated. The oxygen carriers were produced by spray-drying and calcined at 1150 degrees C. The resistance toward sulfur and the rates of oxygen release were evaluated in a laboratory-scale fluidized-bed reactor. It was found that the combined Mn-Si oxygen carrier is tolerant to SO2, at least up to a partial pressure of 5000 vppm. The rates of oxygen release were determined in the temperature range of 975 to 1100 degrees C using devolatilized wood char as fuel while fluidizing with N-2, to maintain a low oxygen partial pressure surrounding the particles. The Arrhenius parameters k(o) and E-app for the release of oxygen were estimated for the investigated materials assuming a zero-order reaction with respect to oxygen. The rates of oxygen release were relatively high, particularly at above 1050 degrees C. From the obtained reaction rates, the solids inventory required for combustion of coal was determined to be as low as 40 kg/MWth in the fuel reactor at 1100 degrees C. The results indicated that combined Mn-Si oxygen carriers could be interesting materials for the CLOU process by virtue of their resistance to sulfur deactivation and high rate of oxygen release.
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12.
  • Arjmand, Mehdi, 1986, et al. (författare)
  • Sulfur Tolerance of CaxMn1–yMyO3−δ (M = Mg, Ti) Perovskite-Type Oxygen Carriers in Chemical-Looping with Oxygen Uncoupling (CLOU)
  • 2014
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 28:2, s. 1312-1324
  • Tidskriftsartikel (refereegranskat)abstract
    • Perovskite-structured oxygen carriers of the type CaxMn1–yMyO3−δ (M = Mg, Ti) have been investigated for the CLOU process. The oxygen carrier particles were produced by spray-drying and were calcined at 1300 °C for 4 h. A batch fluidized-bed reactor was used to investigate the chemical-looping characteristics of the materials. The effect of calcium content, dopants (Mg and Ti), and operating temperature (900, 950, 1000, and 1050 °C) on the oxygen uncoupling property and the reactivity with CH4 in the presence and absence of SO2 was evaluated. In addition, the attrition resistance and mechanical integrity of the oxygen carriers were examined in a jet-cup attrition rig. All of the investigated perovskite-type materials were able to release gas phase oxygen in inert atmosphere. Their reactivity with methane was high and increased with temperature and calcium content, approaching complete gas yield at 1000 °C. The reactivity decreased in the presence of SO2 for all of the investigated oxygen carriers. Decreasing the calcium content resulted in a less severe decrease in reactivity in the presence of SO2, with the exception of materials doped with both Mg and Ti, for which a higher resistance to sulfur deactivation could be maintained even at higher calcium contents. The drop in reactivity in the presence of SO2 also decreased at higher temperatures, and at 1050 °C, the decrease in the reactivity of the Mg- and Ti-doped material was minimal. Sulfur balance over the reactor system indicated that the fraction of the introduced SO2 that passed through the reactor increased with temperature. It was shown that it is possible to regenerate the oxygen carriers during reduction in the absence of SO2. Most of the materials also showed relatively low attrition rates. The results indicate that it is possible to modify the operating conditions and properties of perovskite-type oxygen carriers to decrease or avoid their deactivation by sulfur.
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13.
  • Aronsson, Jesper, 1985, et al. (författare)
  • Improved Gas-Solids Mass Transfer in Fluidized Beds: Confined Fluidization in Chemical-Looping Combustion
  • 2019
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 33:5, s. 4442-4453
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2019 American Chemical Society. Fluidized bed processes with reactive bed material have become increasingly popular as research topics, with applications such as chemical-looping technologies, oxygen carrier aided combustion, and fluidized bed gasification being extensively investigated. When used at commercial scale the performance of such processes may be limited not by gas-solid reactivity, but by mass transfer of reactants from bubbles to the emulsion phase. In an effort to break down the two-phase flow structure, and thereby increase the bubble-emulsion mass transfer coefficient, spherical packing material was added to a fluidized bed using ilmenite as bed material. Two types of packing were tested: expanded clay aggregate (ECA) and aluminum silicate balls (ASB). Both packings had a diameter of about 12 mm but drastically different bulk densities of 240 kg/m 3 and 1400 kg/m 3 , respectively. These were tested in chemical-looping-combustion batch experiments using a stainless-steel reactor with a diameter of 78 mm, with syngas or carbon monoxide as fuel at 915 °C. The lighter packing formed a floating plug while the heavier remained stationary at the reactor bottom. To compare the confined fluidized bed to a reference conventional one, a simple reaction model was implemented based on the experiments. It showed that in the confined fluidized bed the associated effective reaction rate constant increased by up to a factor of 2 for a given bed mass. Further, up to 4 times less oxygen carrier bed mass was needed to achieve the same gas conversion, at a lower total pressure drop. Experiments with only carbon monoxide showed similar gains when using aluminum silicate balls, indicating that catalysis of the water gas shift reaction was not the main factor for improved gas conversion. It can be concluded that the concept of confined fluidization has great potential to increase mass transfer in fluidized beds with active bed material.
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14.
  • Azad, Abdul-Majeed, 1957, et al. (författare)
  • Examining the Cu-Mn-O Spinel System as an Oxygen Carrier in Chemical Looping Combustion
  • 2013
  • Ingår i: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 1:1, s. 59-69
  • Tidskriftsartikel (refereegranskat)abstract
    • Chemical-looping combustion (CLC) and chemical-looping combustion with oxygen uncoupling (CLOU) are attractive alternatives to conventional combustion that provide efficient and direct separation of CO2. Both processes use metaloxides as oxygen carriers to transfer oxygen between two reactor vessels: the air and fuel reactors. Although monometallic oxides (such as Mn3O4, Fe2O3, NiO, and CuO) have been successfully employed as oxygen carriers, double oxides of the general formula CuxMn3_xO4 in the CuO–Mn2O3 system are examined in this work. The carrier was produced by mixing, extruding, and calcining a 1:1 molar (30.8:69.2 mass ratio) mixture of CuO and Mn2O3 at 950 8C for 6 or 12 h in static air. XRD analysis revealed that spinels of the general formula CuxMn3_xO4 were formed with 0.1_x_2.5 in which x=3Cu/(Cu+Mn). The chemical-looping performance was evaluated in a laboratory-scale fluidized-bed reactor from 800–850 8C over several alternating redox cycles using CH4 as the fuel. The oxygen carrier exhibited reproducible and stable reactivity behavior for both reducing and oxidizing periods in this temperature range. This characteristic makes the system an ideal oxygen-carrier material for CLOU. Moreover, the spinels in the CuxMn3_xO4 series are endowed with favorable physicochemical attributes (such as fast redox processes, high crushing strength, and demonstrated CLOU behavior) and may be viable alternatives to CuO–Cu2O and Mn2O3–Mn3O4 as potential CLOU materials.
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15.
  • Azimi, Golnar, 1985, et al. (författare)
  • Comprehensive study of Mn–Fe–Al oxygen-carriers for chemical-looping with oxygen uncoupling (CLOU)
  • 2015
  • Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 34, s. 12-24
  • Tidskriftsartikel (refereegranskat)abstract
    • The reactivity and attrition resistance of Mn–Fe oxygen carriers with addition of Al2O3 as support have been investigated. Spray-dried oxygen-carrier particles with Mn:Fe molar ratios of 80:20 and 33:67 were prepared using different amounts of Al2O3. Each material was calcined for 4 h at 950 °C, 1100 °C or 1200 °C. The oxygen carriers were studied in a batch fluidized bed reactor to investigate their reactivity with wood char, CH4, syngas and also their oxygen release in N2. In order to measure the mechanical stability of the different materials, the attrition resistance was measured in a jet-cup apparatus. Addition of Al2O3 to materials with a Mn:Fe molar ratio of 80:20 was not advantageous. Generally oxidation of these materials was problematic. The Al2O3 supported materials with a Mn:Fe molar ratio of 80:20 calcined at 950 °C and 1100 °C showed poor attrition resistance and were highly fragmented or turned to dust, whereas those calcined at 1200 °C showed high attrition resistance but poor gas conversion.Materials with a Mn:Fe molar ratio of 33:67 supported with Al2O3 generally showed better attrition resistance. Also their oxidation with 5 vol% of oxygen was possible at temperatures higher than 850 °C. Furthermore, some of these materials showed good reactivity with methane, syngas and char. Low attrition, good reactivity and CLOU properties in combination with potentially low raw materials costs, make these materials interesting for CLC.
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16.
  • Azimi, Golnar, 1985, et al. (författare)
  • Investigation of Different Mn–Fe Oxides as Oxygen Carrier for Chemical-Looping with Oxygen Uncoupling (CLOU)
  • 2013
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:1, s. 367-377
  • Tidskriftsartikel (refereegranskat)abstract
    • The appropriate oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) should be thermodynamically capable of being oxidized in the air reactor and also release gaseous O2 in the fuel reactor at appropriate temperatures and oxygen partial pressures. It should also be mechanically durable, cheap, and environmentally friendly. Iron–manganese oxides appear to be especially promising due to favorable thermodynamics. In this work, combined metal oxides of iron and manganese were investigated for the CLOU process. Particles with different ratios of Mn/Fe were produced using spray drying. The particles were calcined at 950 and 1100 °C for 4 h and then tested with respect to parameters important for CLOU. The crushing strength for these materials was between 0.1 to 1.7 N, depending on their composition and sintering temperature. The ability of the iron–manganese oxide particles to release oxygen in the gas phase was examined by decomposition of the material in a stream of N2. Moreover, the reaction with both methane and synthesis gas (50/50% CO/H2) was examined in a batch fluidized bed reactor. Here, the particles were alternately oxidized with 5% O2 and reduced in N2 or with fuel at 850 °C, 900 and 950 °C. From the results, it can be concluded that during the nitrogen period, the oxygen carriers with Mn3O4 content in the range from 20 wt % to 40 wt % release oxygen at 900 °C, whereas the materials with higher manganese content show no oxygen release. This is because they could not be oxidized to bixbyite. By decreasing the temperature from 900 to 850 °C, it was possible to oxidize oxygen carriers with manganese oxide content of 50 wt % and higher, and consequently, oxygen release during the nitrogen period was seen for these materials. This is in agreement with the phase diagram for this system. The reaction rate with methane follows the oxygen release trend very well. At the higher reaction temperature, 950 °C, oxygen carriers with manganese content in the range from 25% to 33% show the best gas conversion of methane. At 850 °C, on the other hand, high methane conversion is seen for particles with high manganese content. In fact, several particles had almost full conversion of methane to CO2 and H2O at 850 °C using a bed mass in the batch reactor corresponding to 70 kg oxygen carrier/MW.
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17.
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18.
  • Azimi, Golnar, 1985, et al. (författare)
  • Mn–Fe Oxides with Support of MgAl2O4, CeO2, ZrO2 and Y2O3–ZrO2 for Chemical-Looping Combustion and Chemical-Looping with Oxygen Uncoupling
  • 2014
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 53:25, s. 10358-10365
  • Tidskriftsartikel (refereegranskat)abstract
    • The feasibility of utilizing a combined oxide (Mn0.75Fe0.25)(2)O-3 as an oxygen carrier for chemical-looping with oxygen uncoupling (CLOU) has been investigated. To increase the strength and attrition resistance of such particles, the oxygen carrier was prepared together with MgAl2O4, CeO2, ZrO2 and Y2O3-ZrO2 as supports. The oxygen-carrier particles were prepared using spray-drying. Each material was calcined for 4 h at 950, 1100 or 1200 degrees C. The materials were studied in a batch fluidized bed reactor to investigate their oxygen release and uptake potential and also their reactivity with CH4 and syngas. To gauge the mechanical stability of the different materials, the attrition resistance was measured in a jet-cup apparatus. With the exception of the material with MgAl2O4, the oxygen uncoupling property of the active combined oxides was largely kept intact using the added support materials. On the basis of the results from the reactivity tests and the measured attrition rates for all the particles, the material utilizing ZrO2 support seems to be the most promising candidate as an oxygen carrier for gaseous and solid fuels. However, due to phase transformations of the ZrO2 at higher temperatures, the calcination and operational temperature should likely not exceed 950 degrees C.
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19.
  • Azimi, Golnar, 1985, et al. (författare)
  • (MnzFe1—z)yOx combined oxides as oxygen carrier for chemical-looping with oxygen uncoupling
  • 2013
  • Ingår i: AICHE Journal. - : Wiley. - 1547-5905 .- 0001-1541. ; 59:2, s. 582-588
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen carrier particles with the composition (Mn0.8,Fe0.2)2O3 were found to readily release gas phase oxygen at 850°C, and were capable to oxidize CH4 completely and convert wood char rapidly to CO2 during experiments in a batch fluidized bed reactor. The particles were able to release oxygen corresponding to more than 3% of their mass in less than 40 s. Because of the low price and favourable environmental properties of manganese and iron oxides, this finding could be of great importance for the development of chemical-looping combustion with oxygen uncoupling
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20.
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21.
  • Berdugo Vilches, Teresa, 1985, et al. (författare)
  • Experience of more than 1000 h of operation with oxygen carriers and solid biomass at large scale
  • 2017
  • Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 190, s. 1174-1183
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents an overview of the experience gained from operating a dual fluidized bed system with oxygen carriers and biomass for more than 1000 h. The tests were carried out in the Chalmers boiler/gasifier loop (with inputs of 12 MWth and 2–4 MWth, respectively), which is 2–4 orders of magnitude larger than most existing CLC units. Coarse biomass particles (i.e., commercial wood pellets) were fed as fuel onto the surface of a mild fluidized bed. This limits significantly the contacts between the volatiles and the oxygen carrier particles, as the flotsam fuel tends to remain on the surface of the bed while the volatiles are released. The oxygen carrier materials tested were ilmenite and a manganese ore. The influences on biomass conversion of fluidization velocity, fuel feeding rate, and circulation rate of the bed material were investigated. Both bed materials efficiently transported oxygen between the reactors, achieving up to 60% combustion of the gases released in the reactor at a relatively low temperature, i.e., 830 °C. The ilmenite outperformed the manganese ore under the conditions investigated. With oxygen carriers, the yield of hydrocarbons heavier than benzene was in the range of 10–11 g/N m3, which was 70% (w/w) lower than that obtained in a reference case with silica-sand as the bed material. The conversion of volatile species to CO2 was limited by gas-solids mixing, which could be enhanced by altering the fluidization velocity. The circulation rate of the bed material and the fuel feeding rate were found to have important influences on the rate of char gasification. Given the relatively low operating temperature and the simple reactor design, relatively high conversion of biomass by the oxygen carriers was achieved. There is scope for further optimization of the operating conditions, to achieve higher conversion levels, which would enable the implementation of CLC of biomass on a large scale. © 2017 Elsevier Ltd
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22.
  • Eliasson Störner, Felicia, 1994, et al. (författare)
  • An improved method for feeding ash model compounds to a bubbling fluidized bed – CLC experiments with ilmenite, methane, and K 2 CO 3
  • 2023
  • Ingår i: Greenhouse Gases: Science and Technology. - 2152-3878. ; 13:4, s. 546-564
  • Tidskriftsartikel (refereegranskat)abstract
    • Biomass conversion with carbon capture and storage (Bio-Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical-looping combustion (CLC) is examined in which the CO2 is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen carriers; solid metal oxides that provide oxygen for the conversion process. Biomass and waste-derived fuels contain reactive ash compounds, such as potassium, and interactions between the oxygen carrier and the ash species are critical for the lifetime and performance of the oxygen carrier. This work develops and demonstrates an improved method for studying the interactions between ash species and oxygen carriers. The method uses a lab-scale reactor operating under fluidized conditions, simulating CLC batch-wise by switching between feed gas. The novelty of the setup is the integrated system for feeding solid particles of ash model compounds, enabling the simulation of ash species accumulating in the bed. Ilmenite is a benchmark oxygen carrier for solid fuel conversion and was used in this study to evaluate the method using K2CO3 as a model ash compound. Experiments were done at 850 and 950°C. Methane conversion in CLC cycles and fluidization was evaluated with gas analysis and pressure drop measurements. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD) analysis of bed particles were done after the experiments to establish changes in the morphology and composition of the ilmenite. The method for feeding the ash model compound was concluded to be satisfactory. At 950°C, K accumulated in the particles forming K-titanates and agglomeration was enhanced with K2CO3 addition. The agglomeration mechanism was solid-state sintering between the Fe-oxides forming on the particle surfaces. The bed defluidized at 950°C, but no such effect was seen at 850°C. The method is suitable for studying the Fe-Ti-K system with ilmenite and potassium without the influence of other ash species. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.
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23.
  • Eliasson Störner, Felicia, 1994, et al. (författare)
  • Oxygen Carrier Aided Combustion in Fluidized Bed Boilers in Sweden - Review and Future Outlook with Respect to Affordable Bed Materials
  • 2021
  • Ingår i: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 11:17
  • Forskningsöversikt (refereegranskat)abstract
    • Oxygen carriers are metal oxide particles that could potentially enhance both fuel conversion and heat distribution in fluidized bed combustion, resulting in e.g., lowered emissions of unconverted species and better possibilities to utilize low‐grade fuels. A related technology based on fluidized beds with oxygen carriers can separate CO2 without large energy penalties. These technologies are called oxygen carrier aided combustion (OCAC) and chemical‐looping combustion (CLC), respectively. In the past few years, a large number of oxygen carriers have been suggested and evaluated for these purposes, many of which require complex production processes making them costly. Affordable metal oxide particles are, however, produced in large quantities as products and byproducts in the metallurgical industries. Some of these materials have properties making them potentially suitable to use as oxygen carriers. Uniquely for Sweden, the use of oxygen carriers in combustion have been subject to commercialization. This paper reviews results from utilizing low‐cost materials emerging from metallurgical industries for conversion of biomass and waste in semi‐commercial and commercial fluidized bed boilers in Sweden. The paper further goes on to discuss practical aspect of utilizing oxygen carriers, such as production and transport within the unique conditions in Sweden, where biomass and waste combustion as well as metallurgical industries are of large scale. This study concludes that utilizing metal oxides in this way could be technically feasible and beneficial to both the boiler owners and the metallurgical industries.
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24.
  • Eliasson Störner, Felicia, 1994, et al. (författare)
  • Potassium Ash Interactions with Oxygen Carriers Steel Converter Slag and Iron Mill Scale in Chemical-Looping Combustion of Biomass - Experimental Evaluation Using Model Compounds
  • 2020
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 34:2, s. 2304-2314
  • Tidskriftsartikel (refereegranskat)abstract
    • Chemical-looping combustion (CLC) is a combustion technology in which a solid oxygen carrier is used to convert fuel. The oxygen carrier is oxidized in air and subsequently transferred to a separate reactor in which it reacts with the fuel. The produced CO2 is inherently separated from the air components, making CLC a promising technology for carbon capture and storage (CCS). CLC of biomass combined with CCS (bioenergy CCS; BECCS) is a way to generate negative CO2 emissions and thus interesting for climate change mitigation. Undesirable chemical reactions between ash and oxygen carriers are a challenge in BECCS because of the reactive nature of biomass ash. This article examines two low-cost steel industry byproducts that have shown desirable fuel conversion properties in CLC: iron mill scale (Glödskal B) and steel converter slag (LD-slag). Their interactions with potassium ash model compounds (KCl, K2CO3,K2SO4, and KH2PO4) in a reducing atmosphere have been investigated. Mixtures of oxygen carriers and potassium salt have been reduced for 6 h in CO and steam in a laboratory-scale fixed-bed reactor at 850 °C. The reduced samples have been analyzed with SEM/EDS and XRD. The reactivity of the mixtures during reduction and oxidation has also been examined by thermogravimetric analysis (TGA). K2CO3 increased the reaction rate for the reduction of Glödskal and inhibited the reactivity of LD-slag. KH2PO4 formed a K−P−Fe component with apparent low melting temperature with Glödskal, causing agglomeration, and decreased the reduction/oxidation rate in TGA. KH2PO4 formed a K−P−Ca component with apparent high melting temperature with LD-slag causing agglomeration but the reduction rate was not affected. The study suggests that the iron mill scale and LD-slag should not be rejected as oxygen carriers for CLC based on potassium ash interaction.
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25.
  • Frick, Volkmar, 1983, et al. (författare)
  • Investigation of Cu-Fe and Mn-Ni oxides as oxygen carriers for chemical-looping combustion
  • 2016
  • Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 150, s. 30-40
  • Tidskriftsartikel (refereegranskat)abstract
    • Combined Cu-Fe and Mn-Ni oxygen carriers were investigated as bed" materials for-chemical-looping combustion.,The aim was to identify material combinations which yield oxygen carriers with a high reactivity towards gaseous fuels, such as CO, H-2 and CH4, as well as sufficient mechanical durability. For this purpose, 18 different oxygen carriers were spray-dried and calcined at defined temperatures. Gas conversion as well as release of gaseous oxygen was-investigated in a batch fluidized bed reactor setup at temperatures between 850 and 1050 degrees C. For testing the mechanical durability; a jet-cup attrition rig was used. Moreover, properties like specific surface area, oxygen transfer capacity and crystalline phase composition were examined to physically and chemically characterize the oxygen carrier particles. For both the Cu-Fe and Mn-Ni-based materials, oxygen carriers could be produced which showed a high reactivity with gaseous fuels like CO or CH4 while having a sufficiently high mechanical strength. These properties make them interesting candidates for application in chemical-looping combustion. (C) 2016 Elsevier B.V. All rights reserved.
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26.
  • Frick, Volkmar, 1983, et al. (författare)
  • Screening of supported and unsupported Mn-Si oxygen carriers for CLOU (chemical-looping with oxygen uncoupling)
  • 2015
  • Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 93, s. 544-554
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen carriers based on oxides of Mn and Si in combination with Mg, Al, Ca and Ti (Mn0.63Si0.27X0.1, X = Ca(OH)2, TiO2, MgO, AlOOH) were examined for CLOU (chemical-looping with oxygen uncoupling), in terms of oxygen uncoupling ability and ability to convert both methane and syngas. The focus was on the optimization of the production process to yield mechanically strong oxygen carrier particles with a reasonable activity. For this purpose, 15 types of oxygen carriers were produced by spray-drying and calcined for different time periods and at different temperatures. The oxygen uncoupling behavior and gas conversion of the materials were investigated in a batch fluidized-bed reactor under alternating oxidizing and reducing conditions in the temperature range 850-1050 °C. To determine attrition resistance and mechanical stability, a jet-cup attrition rig was used. Furthermore, physical and chemical properties such as specific surface area and crystal phase composition have been determined. For the oxygen carriers with additives of Mg, Al, Ca, Ti, some material combinations showed a significant increase in reactivity and improved mechanical stability compared to the unsupported Mn-Si particles. Changing the production process (milling process and calcination time) just caused slight difference in attrition resistance, gas conversion as well as oxygen release.
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27.
  • Hallberg, Peter, 1984, et al. (författare)
  • CaMnO3-δ Made from Low Cost Material Examined as Oxygen Carrier in Chemical-looping Combustion
  • 2014
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 63, s. 80-86
  • Konferensbidrag (refereegranskat)abstract
    • Carbon Capture and Storage is a promising method to limit the increasing amount of greenhouse gases in the atmosphere. In this method high purity carbon dioxide is captured at large emission sources, e. g. fossil fuelled power plants. The carbon dioxide can then be transported to a long term storage site, rather than being emitted to the atmosphere. Among the different alternatives for obtaining high purity carbon dioxide during combustion of fossil fuels, Chemical-looping Combustion (CLC) is one of the most promising. Here, the oxygen needed to oxidize a fuel is provided by a solid oxygen carrier. The oxygen carrier is subsequently circulated to another reactor where it is reoxidized with air. By separating these two operations mixing of the combustion products and the nitrogen in the air is avoided. An energy demanding gas separation is thus not necessary.The most crucial part of Chemical-looping Combustion is the solid oxygen carrier. The oxygen carrier should have high reactivity with fuel and oxygen, sufficient oxygen carrying capacity and preferably also low cost. Furthermore it is important that it is able to withstand the tough conditions it is exposed to in a hot fluidizing environment, both with respect to physical attrition and chemical degradation. The most commonly suggested setup of Chemical- looping Combustion is a dual fluidized bed system where gas velocities and mechanical abrasion can be high. When the technology was first demonstrated, nickel oxide based oxygen carriers were typically used. But as nickel is quite costly as well as potentially harmful, alternatives have been sought after.In 2009 Leion et al. [1] investigated an oxygen carrier based on calcium manganite of perovskite structure CaMnO3-δ for chemical looping combustion. The results were very promising and similar materials have since then been successfully tested in pilot rigs up to 120 kWth, including extended operation in continuously operating 10 kWth reactor with very positive results, see Källén et al. [2]. A key feature of these materials is that they are able to release gas phase oxygen at relevant conditions, so called Chemical-looping with Oxygen Uncoupling, see Rydén et al. [3]. Having gas phase oxygen available for fuel oxidation makes gas-solid mixing less critical and thus makes it easier to reach complete fuel conversion.Most studies in which CaMnO3-δ based oxygen carriers have been examined have been using particles manufactured from high quality chemicals. While that is reasonable in the early stages of development, cheaper raw materials would be favourable for industrial applications. Promising oxygen carriers based on manganese ores have been manufactured and characterized by Fossdal et al. [4] and Mohammad Pour et al. [5].This study aims to further examine CaMnO3-δ based oxygen carriers made from low cost, commercial raw materials available in large quantities such as manganese ore. The materials are examined during continuous Chemical- looping Combustion and Oxygen Uncoupling in an experimental reactor with the nominal fuel power 300 Wth. The reactor has previously been used in numerous studies which make comparisons with materials made from high purity chemicals straightforward. During operation several gas concentrations as well as temperatures and pressure drops are measured which allows monitoring of the chemical reactions and fluidization behaviour in the reactor.Fines (particles
  •  
28.
  • Hallberg, Peter, 1984, et al. (författare)
  • Chemical Looping Combustion and Chemical Looping with Oxygen Uncoupling Experiments in a Batch Reactor Using Spray-Dried CaMn1–xMxO3−δ (M = Ti, Fe, Mg) Particles as Oxygen Carriers
  • 2013
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 27:3, s. 1473-1481
  • Tidskriftsartikel (refereegranskat)abstract
    • Chemical looping combustion and chemical looping with oxygen uncoupling (CLOU) with oxygen carrier particles consisting of CaMn1-xMxO3-delta (M = Ti, Fe, Mg) has been studied by consecutive oxidation and reduction experiments in a fluidized-bed batch reactor. The examined particles were produced by spray drying, and all did show a significant release of gas-phase oxygen to the inert atmosphere at 900 and 1000 degrees C. All particles also provided very high reactivity with syngas and methane. Some of the examined particles showed unfavorable fluidization characteristics, i.e., they formed dust during operation or showed agglomeration or defluidization tendencies. The crushing strength of the particles that formed dust was typically
  •  
29.
  • Hallberg, Peter, 1984, et al. (författare)
  • Experimental investigation of CaMnO3-δ based oxygen carriers used in continuous Chemical-Looping Combustion
  • 2014
  • Ingår i: International Journal of Chemical Engineering. - : Hindawi Limited. - 1687-806X .- 1687-8078. ; 2014:412517
  • Tidskriftsartikel (refereegranskat)abstract
    • Three materials of perovskite structure, (M = Mg or Mg and Ti), have been examined as oxygen carriers in continuous operation of chemical-looping combustion (CLC) in a circulating fluidized bed system with the designed fuel power 300 W. Natural gas was used as fuel. All three materials were capable of completely converting the fuel to carbon dioxide and water at 900°C. All materials also showed the ability to release gas phase oxygen when fluidized by inert gas at elevated temperature (700–950°C); that is, they were suitable for chemical looping with oxygen uncoupling (CLOU). Both fuel conversion and oxygen release improved with temperature. All three materials also showed good mechanical integrity, as the fraction of fines collected during experiments was small. These results indicate that the materials are promising oxygen carriers for chemical-looping combustion.
  •  
30.
  • Hallberg, Peter, 1984, et al. (författare)
  • Investigation of a calcium manganite as oxygen carrier during 99 h of operation of chemical-looping combustion in a 10 kWth reactor unit
  • 2016
  • Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 53, s. 222-229
  • Tidskriftsartikel (refereegranskat)abstract
    • Chemical-looping with oxygen uncoupling is a technology for combustion with inherent carbon dioxide separation. A solid oxygen carrier circulates between the fuel reactor, where it provides oxygen for fuel oxidation, and the air reactor, where it is reoxidized. In this study a 10 kWth pilot reactor was used to examine a calcium manganite based oxygen carrier in continuous operation with natural gas as fuel during 99 h. The composition of the oxygen carrier can be described by the formula CaMn0.775Ti0.125Mg0.1O3-δ. The main part of the material forms a perovskite crystal structure which has oxygen releasing properties. The fuel conversion was generally above 95% and full conversion was reached for certain operating conditions. The elutriation of fines, defined as particles smaller than 45 μm, decreased over time to eventually be below detection limit. That suggested a loss of fines of less than 0.011 wt%/h, indicating a lifetime of over 9000 h. A high fuel conversion with no thermodynamic limitation, good mechanical strength, low cost and very low toxicity shows that this calcium manganite material qualifies as a very promising oxygen carrier.
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31.
  • Hanning, Malin, 1987, et al. (författare)
  • Biomass ash interactions with a manganese ore used as oxygen-carrying bed material in a 12 MWth CFB boiler
  • 2018
  • Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 1873-2909 .- 0961-9534. ; 119, s. 179-190
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen carrier aided combustion (OCAC) is a combustion concept which utilises oxygen carriers as bed material in existing fluidised bed boilers. In this study, a manganese ore was used in a 12 MWthCFB boiler. During the experimental session with the manganese ore, the boiler was operated with wood chips as fuel for more than a week without replacement of the bed material. Bed samples were extracted each day in order to investigate interactions between the manganese ore and the wood ash components. The samples were examined with SEM/EDX to follow the chemical distribution of ash elements in the bed particles. Physical properties such as density, size distribution and attrition resistance were followed as well. The impact on the reactivity of the oxygen-carrier bed particles was examined in a batch fluidised bed reactor at laboratory scale with gaseous fuels. Elemental composition analysis of the samples showed that common ash elements such as silicon, calcium, potassium, magnesium and sulphur had been accumulated in the manganese ore. Silicon, calcium and potassium were found throughout the particles as well as in formed surface layers. Sulphur was only found at the surface of the particles. The reactivity of the oxygen-carrying particles was affected during operation and showed a continuous decrease with increasing residence time in the boiler. The decrease in reactivity could be coupled to the layers of ash formed. Thus, this is an important issue when developing novel combustion concepts, such as OCAC and chemical-looping combustion (CLC), for biomass fuels.
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32.
  • Hanning, Malin, 1987, et al. (författare)
  • CaMn0.9Mg0.1O3-δ as Oxygen Carrier in a Gas-Fired 10 kWth Chemical-Looping Combustion Unit
  • 2013
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 52:21, s. 6923-6932
  • Tidskriftsartikel (refereegranskat)abstract
    • Spray dried particles of the perovskite material CaMn0.9Mg0.1O3-δ have been examined as oxygen carrier for chemical-looping combustion of natural gas. The experiments have been conducted in a continuously operating reactor with the nominal size 10 kWth. The oxygen carrier particles showed excellent ability to convert fuel and complete combustion was reached at certain conditions. In general, the CO2 yield increased with increased fuel reactor temperature and with increased circulation rate. The oxygen carrier was able to release gaseous oxygen through the so called CLOU-mechanism (Chemical-Looping with Oxygen Uncoupling). When the fuel reactor was fluidized by inert gas, there was oxygen release at temperatures above 700°C, reaching a maximum of more than 3% for temperatures above 850°C. Gas phase oxygen was also measured during operation with fuel, as long as the fuel conversion was complete. When the fuel reactor temperature was above 900°C and a high enough circulation rate was maintained, complete combustion of the fuel was achieved with an oxygen concentration in the outlet stream from the fuel reactor of more than 1%. This suggests that a substantial part of the fuel is converted by gaseous oxygen released from the particles. The oxygen carrier particles were subject to more than 350 h of fluidization, of which more than 175 h was at high temperature and more than 55 h with addition of fuel. The particles did not show any tendencies to form hard agglomerations or break down to fines due to attrition during the experiments. Operational problems included high rate of particle elutriation, which was likely an effect of a mismatch between the size and density of the particles, the air flow and the cyclone.
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33.
  • Hanning, Malin, 1987, et al. (författare)
  • Chemical-looping combustion using combined iron/manganese/silicon oxygen carriers
  • 2015
  • Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 157, s. 330-337
  • Tidskriftsartikel (refereegranskat)abstract
    • Combined oxides of iron, manganese and silicon have been used as oxygen carriers for chemical-loopingcombustion. Three materials with varying composition of iron, manganese and silicon have been evaluatedin oxygen release experiments and during continuous operation with syngas and natural gas as fuels. The concentration of oxygen released increased as a function of temperature and the highest concentrations of oxygen were measured with the material with the highest fraction of manganese. It was also this material which gave the best conversion of both syngas and natural gas; essentially full conversion of syngas and above 95% conversion of natural gas above 900° C. The other two materials showedsimilar performance, albeit with higher syngas conversion for the material with the lowest manganesefraction and the lowest conversion of natural gas for the same material. The materials lasted for 10–14 h of operation with fuel addition before circulation disruption occurred, which was likely caused byparticle attrition in all three cases. A phase diagram of the iron–manganese–silicon–oxide system wasconstructed and the possible relevant phase transitions were identified. This analysis showed that morephase transitions could be expected for the materials with higher manganese content which couldexplain the superior performance during fuel operation of the material with the highest manganese content.It should however be noted that this material was operated with the highest fuel reactor inventoryper thermal power which could also be a contributing factor to the better performance of this material.The study shows that it is possible to achieve very high fuel conversion with combined oxides of iron,manganese and silicon as oxygen carrier. The mechanical stability of the particles was rather poor thoughand would need to be improved. On the other hand the findings relating to material stability is not necessaryvalid for natural materials containing a number of additional elements. The results are also of interestas an indication of how natural materials with similar composition, i.e. manganese ores, wouldperform as oxygen carriers.
  •  
34.
  • Hanning, Malin, 1987, et al. (författare)
  • Chemical-Looping Using Combined Iron/Manganese/Silica Oxygen Carriers
  • 2014
  • Ingår i: 3rd International Conference on Chemical Looping, 9-11 September 2014, Göteborg.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Combined oxides of iron, manganese and silica have been used as oxygen carriers for chemical-looping combustion. Three materials with varying composition of iron, manganese and silica have been evaluated in oxygen release experiments and during continuous operation with syngas and natural gas as fuel. The concentration of oxygen released increased as a function of temperature and the highest concentrations of oxygen were measured with the material with the highest fraction of manganese. It was also this material which gave the best conversion of both syngas and natural gas; essentially full conversion of syngas and above 95% conversion of natural gas above 900°C. The other two materials showed similar performance, albeit with higher syngas conversion for the material with the lowest manganese fraction and the lowest conversion of natural gas for the same material. The materials lasted for 10-14 h of operation with fuel addition before circulation disruption occurred, which was likely caused by particle attrition in all three cases. A phase diagram of the iron-manganese-silica system was constructed and the possible relevant phase transitions were identified. This analysis showed that more phase transitions could be expected for the materials with higher manganese content which could explain the superior performance of the material with the highest manganese content. This could possibly also explain the much higher oxygen release of this material. It should however be noted that this material was operated with the highest fuel reactor inventory per thermal power which could also be a contributing factor to the better performance of this material.The study shows that it is possible to achieve very high fuel conversion with combined oxides of iron, manganese and silica as oxygen carrier. The mechanical stability of the particles was rather poor though and would need to be improved. On the other hand the findings relating to material stability is not necessary valid for natural materials containing a number of additional elements. The results are also of interest as an indication of how natural materials with similar composition, i.e. manganese ores, would perform as oxygen carriers.
  •  
35.
  • Hanning, Malin, 1987, et al. (författare)
  • Combined Oxides of Iron, Manganese and Silica as Oxygen Carriers for Chemical-Looping Combustion
  • 2014
  • Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 124:August 2014, s. 87-96
  • Tidskriftsartikel (refereegranskat)abstract
    • Spray-dried particles with the chemical compositions of Fe0.66Mn1.33SiO3 and FeMnSiO3 have been examined as oxygen carrier materials for chemical-looping combustion. The performance of the materials was examined in oxygen release experiments and during fuel operation with natural gas and syngas. The experiments were carried out in a fluidized-bed chemical-looping reactor system designed for a thermal power of 300 W. The reactor system includes an air reactor and a fuel reactor, as well as loop seals and means for circulation of the oxygen carrier particles. Both materials were able to release gas phase oxygen in inert atmosphere at temperatures between 800-950°C, and with approximately equal oxygen concentrations. Fe0.66Mn1.33SiO3 provided higher conversion of natural gas as compared to FeMnSiO3 and the fuel conversion increased with temperature for both materials. During natural gas operation with Fe0.66Mn1.33SiO3 the conversion reached 100% at around 950°C with a fuel reactor inventory of 235 kg/MW. The fuel conversion was improved when the solids inventory was increased; this improvement could especially be observed for FeMnSiO3 as the fuel conversion was lower for this material. Fe0.66Mn1.33SiO3 provided higher fuel conversion than FeMnSiO3 also when syngas was used as fuel. The fuel conversion increased with temperature for both materials and full conversion was reached above 800°C with a fuel reactor inventory of 225 kg/MW for Fe0.66Mn1.33SiO3, while FeMnSiO3 was incapable of providing full conversion. A rather large elutriation of fines and a significant change in particle size distribution could be observed during operation for both materials.Both materials could work as oxygen carrier for chemical-looping with oxygen uncoupling. Fe0.66Mn1.33SiO3 would be preferred as it has higher conversion of both syngas and natural gas, but the attrition behavior of the material would need to be further investigated.
  •  
36.
  • Hanning, Malin, 1987, et al. (författare)
  • Improved Performance in Fluidised Bed Combustion by the Use of Manganese Ore as Active Bed Material
  • 2015
  • Ingår i: 22nd International Conference on Fluidized Bed Conversion, 14-17 June 2015, Turku.
  • Konferensbidrag (refereegranskat)abstract
    • Insufficient mixing between fuel and air during combustion results in carbon monoxide and unburnt hydrocarbons in the flue gases. In order to minimize these emissions commercial combustion plants are operated with an excess of air added to the furnace. This increases the heat loss associated with the flue gas and thus decreases the overall efficiency of the plant. If combustion is carried out in a fluidised bed, the mixing between fuel and oxygen could be facilitated by using an active bed material with the ability to absorb and release chemically bonded oxygen, depending on the local oxygen concentration. Such active oxygen carriers would also facilitate conversion of relatively stable fuel components such as methane inside the bed, where ignition may be hampered by thermal inertia. This technology, Oxygen Carrier Aided Combustion (OCAC), which is a spin-off technology from Chemical-Looping Combustion (CLC), has recently been proposed.In this study, the potential of using manganese ores as active bed material has been investigated. Combustion of methane in a fluidised bed was carried out with two mixtures of manganese ore and silica sand (50/50 wt.%) in a laboratory circulating fluidised bed combustor. The performance of the manganese ores as active bed materials was compared with the performance of only silica sand in the same experimental unit.The main conclusion drawn from these experiments is that it was possible to significantly reduce the exhaust concentration of carbon monoxide by replacing 50 wt.% of the bed inventory of silica sand with manganese ore. Both ores released gaseous oxygen in inert atmosphere and oxygen was present in the exhaust gas at all times during combustion. The use of the active bed materials thus increased the fuel conversion for a given air-to-fuel ratio.
  •  
37.
  • Hanning, Malin, 1987, et al. (författare)
  • Operation with Combined Oxides of Manganese and Silica as Oxygen Carriers in a 300 Wth Chemical-looping Combustion Unit
  • 2014
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 63, s. 131-139
  • Konferensbidrag (refereegranskat)abstract
    • Chemical-looping combustion is a carbon capture technology which has received increased attention during the last years. The technology is based on fuel oxidation with oxygen provided by solid oxygen carrier particles. In this study two such oxygen carrier materials have been examined in a continuously circulating chemical-looping reactor system designed for a thermal power of 300 W. The two materials consisted of manganese and silica oxides, with an addition of titania in one of them. The oxygen carrier particles were produced by spray drying, followed by calcination and sintering. Both materials released gas phase oxygen in inert atmosphere at 800-950 °C, with the highest concentration at 1.8% observed at 850 °C. The oxygen carrier consisting of only manganese and silica gave the highest fuel conversion for both syngas and natural gas. Full fuel conversion was achieved at 950 °C for syngas and at 900 °C for natural gas with this oxygen carrier material. The fuel conversion increased with temperature for both materials. The material consisting of only manganese and silica suffered from severe attrition and could only be operated for seven hours with fuel. The addition of titania increased the mechanical stability of the particles considerably, and this material was operated for 24 h with fuel. No large production of fines was observed with this material. Combined oxides of manganese and silica are shown to be promising as oxygen carriers for chemical- looping. The mechanical stability can be increased by adding titanium to the MnSi material. The composition would however need to be further examined to optimize the performance of the oxygen carrier.
  •  
38.
  • Hanning, Malin, 1987, et al. (författare)
  • Performance of Combined Manganese−Silicon Oxygen Carriers and Effects of Including Titanium
  • 2016
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:2, s. 1171-1182
  • Tidskriftsartikel (refereegranskat)abstract
    • Combined oxides of manganese and silicon have earlier been identified as suitable oxygen carriers for chemical-looping combustion. In this study, one pure manganese-silicon oxide and one similar material with titanium included in the formulation have been examined as oxygen carriers. Experiments studying the oxygen release and the reactivity with syngas, methane and wood char have been carried out in a bench-scale circulating chemical-looping combustor and in a batch fluidized-bed reactor in the temperature range 800-1050°C. Both oxygen carriers released oxygen in inert atmosphere and the concentration of oxygen released increased with temperature. The conversion of syngas and methane also increased with temperature for both materials and in both experimental setups. The reactivity with devolatilized wood char showed that the rate of oxygen uncoupling increased with temperature. However, it could be concluded that the main fuel conversion mechanism was CLC and not CLOU for these materials. The inclusion of titanium in the manganese-silicon combined oxide significantly affected the physical properties of the oxygen carrier particles. The MnSi particles could only be operated for 7 h in the bench-scale circulating chemical-looping combustor before the circulation was disrupted due to the large fines formation. The MnSiTi particles were operated for 24 h in the circulating unit without any circulation disruption. It was concluded that it is possible to greatly decrease the attrition rate of the particles by including titanium in the formulation. However, the inclusion of titanium lowered the reactivity with fuel. As the thermodynamic properties are very similar for the two oxide systems, the reduced reactivity is most probably an effect of the lower porosity of MnSiTi. This emphasizes the importance of optimizing the physical structure of the oxygen carrier particles. The physical structure of the particles was found to be greatly affected by the inclusion of titanium, giving, for example, a higher resistance to attrition. The physical structure of the particles is important for the fuel conversion as well, as it will likely have implications on the internal diffusion in the particles.
  •  
39.
  • Hedayati, Ali, 1984, et al. (författare)
  • Evaluation of Novel Ceria-Supported Metal Oxides As Oxygen Carriers for Chemical-Looping Combustion
  • 2012
  • Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 51:39, s. 12796-12806
  • Tidskriftsartikel (refereegranskat)abstract
    • Oxygen carrier particles consisting of 60 wt % copper, iron, or manganese oxide supported on 40 wt % ceria (CeO2) or gadolinia doped-ceria (Ce0.9Gd0.1O1.9) have been manufactured and examined as oxygen carrier materials for chemical-looping combustion (CLC). Unlike conventional support materials, such as alumina (Al2O3), these ceria-based support materials are active under prevailing conditions in the fuel reactor and have the ability to participate in redox reactions. The oxygen carrier materials were synthesized via extrusion and were examined by successive oxidation and reduction cycles in a bench-scale fluidized bed reactor made of quartz. The experiments were conducted at 900 and 925 degrees C for copper-based materials, and at 950 degrees C for iron- and manganese-based materials. Methane or syngas (50% CO and 50% H-2) using a flow rate of 900 mL/min for Cu-based materials and 450 mL/min for Mn- and Fe-based materials was used as the fuel. For all experiments, 15 g of oxygen carrier was used. The oxidation was performed with a gas mixture of 5% O-2 and 95% N-2. The results show that CeO2 and Ce0.9Gd0.1O1.9 are viable support materials for the oxides of copper and iron. Moreover, the active particles supported on Ce0.9Gd0.1O1.9 were more reactive compared to those supported on CeO2. CH4 was completely converted to CO2 and H2O by CuO supported on Ce0.9Gd0.1O1.9, while the conversion of CH4 for Fe2O3 supported on Ce0.9Gd0.1O1.9 was as high as 90%. Ceria-supported Mn3O4 particles showed poor performance when CH4 was used as fuel. Syngas was fully converted to CO2 and H2O by all the oxygen carriers synthesized and examined in this work. The ability of CuO and Mn2O3 to release O-2 in gas phase when fluidized in inert background was also investigated; in the case of copper oxide, substantial oxygen release was observed. Analysis of fresh and used particles by X-ray diffractometry did not reveal the formation of any unexpected phases. All particles showed good fluidization properties with low attrition and little tendency toward agglomeration.
  •  
40.
  • Hildor, Fredrik, 1992, et al. (författare)
  • Steel converter slag as an oxygen carrier in a 12 MWth CFB boiler – Ash interaction and material evolution
  • 2019
  • Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 88, s. 321-331
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2019 Elsevier Ltd Steel converter slag or LD slag is a byproduct of the basic oxygen steel production process, where raw iron from the blast furnace is converted to steel. LD slag contains mainly calcium and iron compounds and smaller amounts of magnesium, silicon, manganese and vanadium. The iron content, about 17 wt.% of the slag, makes this material a potential oxygen carrier for combustion processes such as Oxygen Carrier Aided Combustion (OCAC) or Chemical Looping Combustion (CLC). This study will present an investigation of the use of LD slag as an oxygen carrier in OCAC at semi-industrial scale. The Chalmers 12 MWth biomass circulating fluidized bed boiler was operated using LD slag as bed material under OCAC conditions. During the operation, bed samples from the boiler were extracted and analyzed with ICP-SFMS, SEM-EDS, XRD and different mechanical tests to analyze chemical and physical changes of the bed material as a function of time. The samples were also investigated in a laboratory fluidized bed reactor to determine the change in reactivity towards common volatile fuel components, i.e. CO, H2, CH4 and C6H6. It was found that LD slag can be utilized as an oxygen carrier in a combustion process for biofuel. However, the reactivity towards syngas, CH4 and C6H6 is reduced as a function of time in the boiler, which is believed to be caused by accumulation of, and interaction with, alkali from the biofuel ash. Sulfur addition may decrease the adverse effects of alkali on combustion efficiency, but not eliminate them completely.
  •  
41.
  • Jing, Dazheng, 1986, et al. (författare)
  • Examination of oxygen uncoupling behaviour and reactivity towards methane for manganese silicate oxygen carriers in chemical-looping combustion
  • 2014
  • Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 29, s. 70-81
  • Tidskriftsartikel (refereegranskat)abstract
    • Cheap and environmental friendly Mn-Si oxygen carriers manufactured from Mn3O4 and SiO2 by spray-drying have been investigated with respect to properties for chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU). Fifteen oxygen carriers with SiO2 content varying from 2wt% to 75wt% were prepared and calcined at 1050°C and 1150°C. The ability of material to release O2 and their reactivity towards CH4 were examined in the temperature range 900-1100°C. Particles with a SiO2 content of more than 45wt% and calcined at 1150°C showed limited CLOU behaviour and poor reactivity towards CH4 at all temperatures investigated. The rest of the materials had significant CLOU properties and provided high conversion of CH4 under the experimental conditions chosen. Increasing the temperature of operation enhanced the CLOU behaviour and reactivity towards CH4. At temperatures above 950°C, the CH4 conversion was 90-100% for these materials. Crystalline phases identified by XRD in the oxidized samples with more than 45wt% SiO2 and calcined at 1150°C were mainly rhodonite MnSiO3. For materials with SiO2 content below 45wt%, braunite Mn7SiO12 was detected as the main phase in most of the samples after oxidation. This indicates that braunite Mn7SiO12 is the main active phase for oxygen transfer in CLC and CLOU, which is supported by thermodynamic calculations. The reactivity of all of the materials were also studied with syngas (50% CO and 50% H2), showing complete gas conversion at 950°C, except for materials with a SiO2 content of more than 45wt% and calcined at 1150°C. The mechanical integrity and attrition resistance of the oxygen carriers were examined in a jet-cup attrition rig, and although the attrition rates varied, some reactive material showed low rates of attrition, making them very promising oxygen carrier materials for applications related to CLC and CLOU. However, measures should probably be taken to improve the crushing strength to some extent. © 2014 Elsevier Ltd.
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42.
  • Jing, Dazheng, 1986, et al. (författare)
  • Examination of Perovskite Structure CaMnO 3-δ with MgO Addition as Oxygen Carrier for Chemical Looping with Oxygen Uncoupling Using Methane and Syngas
  • 2013
  • Ingår i: International Journal of Chemical Engineering. - : Hindawi Limited. - 1687-806X .- 1687-8078. ; 2013
  • Tidskriftsartikel (refereegranskat)abstract
    • Perovskite structure oxygen carriers with the general formula CaMn x Mg 1-x O 3-δ were spray-dried and examined in a batch fluidized bed reactor. The CLOU behavior, reactivity towards methane, and syngas were investigated at temperature 900°C to 1050°C. All particles showed CLOU behavior at these temperatures. For experiments with methane, a bed mass corresponding to 57 kg/MW was used in the reactor, and the average CH 4 to CO 2 conversion was above 97% for most materials. Full syngas conversion was achieved for all materials utilizing a bed mass corresponding to 178 kg/MW. SEM/EDX and XRD confirmed the presence of MgO in the fresh and used samples, indicating that the Mg cation is not incorporated into the perovskite structure and the active compound is likely pure CaMnO 3-δ . The very high reactivity with fuel gases, comparable to that of baseline oxygen carriers of NiO, makes these perovskite particles highly interesting for commercial CLC application. Contrary to NiO, oxygen carriers based on CaMnO 3-δ have no thermodynamic limitations for methane oxidation to CO 2 and H 2 O, not to mention that the materials are environmentally friendly and can utilize much cheaper raw materials for production. The physical properties, crystalline phases, and morphology information were also determined in this work. © 2013 Dazheng Jing et al.
  •  
43.
  • Jing, Dazheng, 1986, et al. (författare)
  • Innovative Oxygen Carrier Materials for Chemical-Looping Combustion
  • 2013
  • Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 37:2013, s. 645-653
  • Konferensbidrag (refereegranskat)abstract
    • In chemical-looping combustion, the oxygen needed for combustion of fuel is provided by metal oxides called oxygen carriers, and inherent separation of CO2 is achieved without energy penalty. For gaseous fuels, such as natural gas, Ni-based oxygen carriers have generally been shown to be the most reactive. But as Ni-based materials are burdened by high costs and environmental risks with respect to toxicity, it is of high importance to find viable non-Ni alternatives. In the EU-financed project INNOCUOUS, one of the key issues is to find novel non-Ni based oxygen carriers. In this paper results from reactivity investigations of three groups of oxygen carrier materials are reported. The materials were prepared by spray-drying, and are based on 1) CuO, 2) Ca-Mn-X-O where X = Cu, Fe, Ti and Mg, and 3) Mg-Mn-O. A number of materials showed a combination of sufficient mechanical strength, high release of gas phase oxygen and high reactivity with methane, and can thus be considered viable alternatives to Ni-based materials.
  •  
44.
  • Leion, Henrik, 1976, et al. (författare)
  • Investigation on ceria- and doped ceria-supported oxygen carriers for CLC applications
  • 2011
  • Ingår i: Technical Workshop at the 3rd Meeting of the IEA-GHG Network on High Temperature Solids Looping Cycles.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • In the area of chemical-looping combustion as a pathway to CO2 sequestration and subsequent storage, major efforts have concentrated on investigating various oxygen carriers supported on inert materials. So, it would be innovative to utilize supports that are participating in the combustion process and thus can act as a minor but additional oxygen carrier or as a facilitating oxidizing catalyst during CLC operation. One of these materials is cerium dioxide (ceria, CeO2), which is used extensively as an integral component of 3-way catalyst in automobiles. In order to exploit the synergy of a composite made up of the active carrier and the participating support, formulations consisting of two-phase mixtures of copper oxide, iron oxide and manganese oxide with pure or doped ceria were fabricated and evaluated for their reactivity in methane and syngas fuel streams. Relevant parameter of significance to CLC process, such as fuel conversion, oxygen release measurement, fluidization properties and, temperature variations during fuel and oxidation cycles, were examined.All the samples showed very good fluidization properties during tests without any agglomeration. Copper oxide-based oxygen carriers showed nearly full conversion of methane with high oxygen release and no sign of defluidization, while iron-based systems exhibited unusually high conversion of methane together with favourable reactivity during oxidation periods after the fuel cycles. The superiority of the GDC-supported materials over those supported on ceria could be interrelated to the better oxygen transport capability of the GDC support due to the oxygen ion vacancies in it by virtue of doping.
  •  
45.
  • Linderholm, Carl Johan, 1976, et al. (författare)
  • Chemical-looping combustion of biomass in a 100 kW pilot
  • 2017
  • Ingår i: European Biomass Conference and Exhibition Proceedings. - 2282-5819. ; 2017:25thEUBCE, s. 412-415
  • Konferensbidrag (refereegranskat)abstract
    • Chemical-looping combustion (CLC) is an innovative carbon-capture technology with potential to drastically reduce the cost of capture. By using a circulating bed material to transfer oxygen from the combustion air to the fuel, air and fuel are never mixed and the CO 2 can be obtained as a separate flue gas stream, undiluted by N 2 . In other words, in contrast to other capture technologies, which are burdened with a significant energy penalty, carbon capture is inherent to the CLC process. Chemical-looping combustion of biomass in combination with carbon capture and storage would lead to so called negative emissions. Manganese ores are highly promising oxygen-carrier candidates due to high reactivity and high availability. Here, we present findings from a 100 kW chemical-looping combustor for solid fuels, using a sintered manganese ore called “Sinaus” as oxygen carrier and two kinds of wood pellets as fuel. Preliminary results from 6 h of operation with steam-exploded wood pellets show fuel conversion up to 75%, and essentially complete CO 2 capture. The expected lifetime of the oxygen carrier particles was found to be 100-400 hours.
  •  
46.
  • Lindroos, Tomi J., et al. (författare)
  • Robust decision making analysis of BECCS (bio-CLC) in a district heating and cooling grid
  • 2019
  • Ingår i: Sustainable Energy Technologies and Assessments. - : Elsevier BV. - 2213-1388. ; 34, s. 157-172
  • Tidskriftsartikel (refereegranskat)abstract
    • Additional investments to negative emission technologies, such as reforestation or bioenergy with carbon capture and storage (BECCS), are required to achieve Paris Agreement targets. Chemical-looping combustion of biomass (Bio-CLC)is an under-the-development combustion technology that could provide relatively low cost negative CO2 emissions. We modelled Bio-CLC units as a part of a city-level district heating and cooling (DHC)grid based on literature and our experimental work with Bio-CLC pilot plants. We applied robust decision-making (RDM)to identify preconditions that favour Bio-CLC over certain competing investment options. In the selected case study, a Bio-CLC unit had a 50% chance to be profitable (10% Internal rate of return or better)around the level of 10 €/tCO2 net income from captured bio-CO2. If the net income from captured bio-CO2 was below 10 €/tCO2, as currently, large heat pumps with COP of 3.5 were the most robust of the studied investment options. Traditional bio-CHP performed better than large heat pumps only when electricity market price was above 50 €/MWh and biomass price below 20 €/MWh. Performed RDM analysis provides a systemic background for both technology developers and DHC operators when considering the competitiveness of the technology in an uncertain future.
  •  
47.
  • Lyngfelt, Anders, 1955, et al. (författare)
  • 11,000 h of chemical-looping combustion operation—Where are we and where do we want to go?
  • 2019
  • Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836. ; 88, s. 38-56
  • Forskningsöversikt (refereegranskat)abstract
    • A key for chemical-looping combustion (CLC) is the oxygen carrier. The ultimate test is obviously the actual operation, which reveals if it turns to dust, agglomerates or loses its reactivity or oxygen carrier capacity. The CLC process has been operated in 46 smaller chemical-looping combustors, for a total of more than 11,000 h. The operation involves both manufactured oxygen carriers, with 70% of the total time of operation, and less costly materials, i.e. natural ores or waste materials. Among manufactured materials, the most popular materials are based on NiO with 29% of the operational time, Fe2O3 with 16% and CuO with 13%. Among the monometallic oxides there are also Mn3O4 with 1%, and CoO with 2%. The manufactured materials also include a number of combined oxides with 11% of operation, mostly calcium manganites and other combined manganese oxides. Finally, the natural ores and waste materials include ilmenite, FeTiO3 with 13%, iron ore/waste with 9% and manganese ore with 6%. In the last years a shift towards more focus on CuO, combined oxides and natural ores has been seen. The operational experience shows a large variation in performance depending on pilot design, operational conditions, solids inventory, oxygen carrier and fuel. However, there is at present no experience of the process at commercial or semi-commercial scale, although oxygen-carrier materials have been successfully used in commercial fluidized-bed boilers for Oxygen-Carrier Aided Combustion (OCAC) during more than 12,000 h of operation. The paper discusses strategies for upscaling as well as the use of biomass for negative emissions. A key question is how scaling-up will affect the performance, which again will determine the costs for purification of CO2 through e.g. oxy-polishing. Unfortunately, the conditions in the small-scale pilots do not allow for any safe conclusions with respect to performance in full scale. Nevertheless, the experiences from pilot operation shows that the process works and can be expected to work in the large scale and gives important information, for instance on the usefulness of various oxygen-carriers. Because further research is not likely to improve our understanding of the performance that can be achieved in full scale, there is little sense in waiting with the scale-up. A major difficulty with the scaling-up of a novel process is in the risk. First-of-its-kind large-scale projects include risks of technical mistakes and unforeseen obstacles, leading to added costs or, in the worst case, failure. One way of addressing these risks is to focus on the heart of the process and build it with maximum flexibility for future use. A concept for maximum flexibility is the Multipurpose Dual Fluidized Bed (MDFB). Another is to find a suitable existing plant, e.g. a dual fluidized-bed thermal gasifier. With present emissions the global CO2 budget associated with a maximum temperature of 2 °C may be spent in around 20–25 years, whereas the CO2 budget for 1.5 °C is may be exhausted in 10 years. Thus, the need for both CO2 neutral fuels and negative emissions will become increasingly urgent as we are nearing or transgressing the maximum amount of CO2 that can be emitted without compromising the global climate agreement in Paris saying we must keep “well below” 2 °C and aim for a maximum of 1.5 °C. Thus, biomass may turn out to be a key fuel for Carbon Capture and Storage (CCS), because CO2-free power does not necessarily need CCS, but negative emissions will definitely need Bio-CCS.
  •  
48.
  • Lyngfelt, Anders, 1955, et al. (författare)
  • Chemical-Looping Combustion (CLC) of Solid Fuels (SF-CLC) A Discussion of Operational Experiences, Costs, Upscaling Strategies and Negative Emissions (Bio-CLC)
  • 2018
  • Ingår i: GHGT 2018 - 14th International Conference on Greenhouse Gas Control Technologies.
  • Konferensbidrag (refereegranskat)abstract
    • Chemical-Looping Combustion (CLC) is a technology which ideally is able to avoid all the costs associated with gas separation, well known to be the major cost, as well as the major reason for large loss in energy efficiency, of CO2 Capture and Storage (CCS). The reason is that the oxygen is transferred from air to fuel using an oxygen-carrier, thus avoiding the mixing of air and fuel, meaning that the combustion products, CO2 and H2O, end up in a separate stream. The H2O is easily removed by condensation resulting, ideally, in a pure CO2 stream. Furthermore, when applied to solid fuels a CLC boiler may be constructed very similar to a circulating fluidized bed (CFB) boiler, and analyses of the cost differences indicate a low added investment cost for a CLC boiler as compared to a CFB boiler. The CLC process has been operated in more than 39 smaller pilots, for a total of more than 10,000 h. The experience with solid fuels show a large variation in performance depending on pilot design, operational conditions, solids inventory, oxygen carrier and fuel. However, there is at present no experience of the process at commercial or semi-commercial scale, although oxygen-carrier materials have been successfully used in commercial boilers for a related process, Oxygen-Carrier Aided Combustion (OCAC) during more than 20,000 h of operation. The paper discusses the lessons learned from pilot operation, the costs, strategies for scale-up, as well as the use of CLC for biomass combustion, i.e. Bio-CLC, in order to attain negative CO2 emissions.
  •  
49.
  • Lyngfelt, Anders, 1955, et al. (författare)
  • Chemical-Looping Combustion of Solid Fuels – What is Needed to Reach Full-Scale?
  • 2016
  • Ingår i: 4th International Conference on Chemical Looping, September 26-28, Nanjing, China.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Because the CO2 capture is inherent in chemical-looping combustion (CLC), thus ideally avoiding costly gas separation, this process has a potential for uniquely low costs of CO2 capture. So what is needed to get to the realization of this technology? The purpose of the paper is to discuss the status of the technology, barriers to the implementation of the technology, and also to suggest routes for the critical path from successful testing in small pilots to implementation in commercial-sized units. Thus, operational experiences with oxygen carriers and chemical-looping with solid fuels are discussed, as well as large scale design and important technology challenges. Moreover, possible routes to scale-up are suggested. One way of lowering the costs of intermediate scale-up steps is to build CLC plants without CO2 purification/compression and oxygen production, because CO2 capture normally only makes sense in large scale. Another way to avoid or minimize the cost of the air reactor, would be by using a CFBB (circulating fluidized bed boiler) as the air reactor. This could either be an existing CFBB which is not in operation or can be taken out of operation for a period, or a designed dual purpose air reactor/CFBB where the CFBB can be used as a stand-alone unit after the testing period with CLC.
  •  
50.
  • Mattisson, Tobias, 1970, et al. (författare)
  • Chemical-Looping Technologies using Circulating Fluidized Bed Systems: Status of Development
  • 2017
  • Ingår i: 12th International Conference on Fluidized Bed Technology, CFB 2017. ; , s. 11-22
  • Konferensbidrag (refereegranskat)abstract
    • In chemical-looping combustion (CLC), an oxygen carrier provides lattice oxygen for complete combustion of a fuel for heat and power production. The reduced metal oxide is then oxidized in a separate reactor. The combustion products CO2 and H2O are obtained in pure form, without any nitrogen in the gas. As no gas separation work is needed, this could be a breakthrough technology for carbon capture (CCS). Normally, the fuel- and air-reactor are designed utilizing inter-connected fluidized beds. The same underlying reversible redox reactions of CLC can be used for other fuel conversion technologies. These include fluidized bed processes for gas, solid and liquid fuels for heat, power, syngas or hydrogen production. Some of these concepts were suggested as far back as the 1950’s, while others have just recently been proposed. Chalmers University of Technology has been involved in CLC research for over 18 years, and this paper will provide a review of some recent developments with respect to CLC with gaseous, liquid and solid fuels. Further, the paper will provide an overview some related technologies where Chalmers is conducting research: i) Chemical-looping gasification (CLG), ii) Chemical-looping reforming (CLR) and iii) Chemical-looping tar reforming (CLTR). In these processes, a pure syngas/hydrogen can be produced effectively, which could be utilized for chemical or fuel production.
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