| 231. |
- Mattisson, Tobias, 1970, et al.
(författare)
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Reactivity of a spray-dried NiO/NiAl(2)O(4) oxygen carrier for chemical-looping combustion
- 2011
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 66:20, s. 4636-4644
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Tidskriftsartikel (refereegranskat)abstract
- Kinetic data of a promising oxygen carrier of NiO/NiAl(2)O(4) have been established from experiments in a small fluidized bed batch reactor using methane. The particles were prepared by spray-drying using commercially available raw material and selected as the best candidates from an earlier screening study. The particles clearly showed high reactivity, with a maximum gas yield between 86% and 93% in the temperature interval 750 degrees C to 950 degrees C when using a bed mass and a gas flow corresponding to only 6 kg/MW(fuel). A comparison of the reactivity with data from TGA experiments showed that the reactivity generally was faster in the batch fluidized bed in the investigated temperature interval. A simple reactor model using kinetic data from the batch fluidized bed reactor and the TGA predicted a minimum mass of 9-24 kg/MW(fuel) of oxygen carrier particles for full gas yield of methane to carbon dioxide in the fuel reactor. Comparison with experiments performed in a 10 and 120 kW CLC reactor with the same type of oxygen carrier showed that even when employing 13 to 50 times the amount of oxygen carrier theoretically needed for complete gas conversion, full gas yield was not obtained in the circulating systems. Hence it is of great importance to consider the fluid dynamics and gas-solid contact when modeling the fuel reactor of a chemical-looping combustor.
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| 232. |
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| 233. |
- Mattisson, Tobias, 1970, et al.
(författare)
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Testing of innovative Fe- and Ca-Mn-based oxygen carriers with natural gas in continuous operation
- 2017
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Ingår i: 9th Trondheim Conference on CO2 Capture, Transport and Storage, Trondheim, Norway, June 12-14, 2017.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Chemical-looping combustion (CLC) of gaseous fuels, such as natural or refinery gas, could be a viable option in a variety of industries for production of heat and electricity with CCS. Further, CLC can be combined with conventional steam–methane reforming for efficientcarbon-neutral hydrogen production. A series of collaborate European projects have been carried out since 2002, which focused on oxygen-carrier development and upscaling of both the CLC process and oxygen-carrier production with natural gas and refinery gas as fuel. Inthe latest project, SUCCESS (2013-2017), a series of oxygen carriers based on Fe and Ca-Mn materials were developed using commercial and low-cost raw materials. Two commercial methods for particle production were used: impregnation of Fe2O3 on Al2O3 and spray-drying of CaMnO3. In this paper, selected results are presented from investigation of these two promising oxygen carriers using a laboratory-scale unit with continuous operation and a nominal fuel input of 10 kWth. In this unit, the gas velocities in the riser and in the grid jet zone of the gas distributor come close to gas velocities of industrial-scale units and the material is exposed to a large number of redox cycles. Therefore, this unit is highly applicable for judging particle lifetime. Both materials functioned well during operation with natural gas, with little or no agglomeration. The total time with fuel was 30 h and >100 h for the impregnated Fe-based material and the Ca-Mn-based material, respectively. Although the degree of elutriation was high for both materials, the actual fines production (
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| 234. |
- Mattisson, Tobias, 1970, et al.
(författare)
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The Nordic CO2 Sequestration (NoCO2) project
- 2006
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Ingår i: 8th International Conference on Greenhouse Gas Control Technologies, Trondheim, Norway, 19-22 June, 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 235. |
- Mattisson, Tobias, 1970, et al.
(författare)
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The presence of CaS in the combustion chamber of a 12 MW circulating fluidized bed boiler
- 1995
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Ingår i: Proceedings of the International Conference on Fluidized Bed Combustion. - 0197-453X. ; 2, s. 819-829
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Tidskriftsartikel (refereegranskat)abstract
- The presence of CaS in bed ashes from a circulating fluidized bed boiler (CFBB) has been studied. The boiler was operated with an excess air ratio of 1.2 but with varying air staging and at temperatures of 850°C and 930°C. The fraction of sulphide sulphur to total sulphur varied between 1 and 4%, with the higher sulphide contents found during intensified staging, that is, when the fraction of air supplied to the bottom bed was low. Under conditions with high SO2 concentrations, due to stopped limestone addition, sulphide to total sulphur fractions of up to 16% were found. In conclusion, a high SO2 concentration, especially in conjunction with intensified air staging, constitutes a risk factor for CaS formation.
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| 236. |
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| 237. |
- Mattisson, Tobias, 1970, et al.
(författare)
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The reaction between limestone and SO2 under periodically changing oxidizing and reducing conditions - Effect of temperature and limestone type
- 1999
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Ingår i: Thermochimica Acta. - 0040-6031. ; 325:1, s. 59-67
-
Tidskriftsartikel (refereegranskat)abstract
- The reaction between limestone and SO2 was investigated under both oxidizing and periodically changing oxidizing and reducing conditions at atmospheric pressure in a fixed-bed quartz reactor. Three limestones of different reactivities were sulfated at temperatures between 800 degrees and 875 degrees C with a gas mixture of 1500 ppm SO2, 10% CO2 and alternating O-2 and CO (0% or 4%). The experimental data found that periodically changing oxidizing and reducing conditions could have either a positive or a negative effect on the degree of conversion of CaO to CaSO4 compared to limestone samples sulfated under constant oxidizing conditions. In the temperature range 825-875 degrees C the conversion was relatively constant for all three limestones under oxidizing conditions. However, when the limestone samples were sulfated with periodically changing oxidizing and reducing gas mixtures a wide range of conversions were found. The highest degree of conversion was found at 825 degrees C for all three limestones and the lowest degree of conversion was found at 875 degrees C. The rapid decrease in conversion at high temperatures was due to the rapid release of SO2 due to both the decomposition of CaSO4 as well as a high rate of CaS oxidation. A comparison of the sulfation rates of several experiments performed with Koping limestone under alternating conditions showed a wide range of rates, indicating the difficulties in using laboratory rate data in sulfur capture modelling for fluidized-bed boilers.
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| 238. |
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| 239. |
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| 240. |
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