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Hydrogen Production with Carbon Dioxide Capture by Reforming of Natural Gas using Chemical-Looping Technologies
| Content Provider | Semantic Scholar |
|---|---|
| Author | Rydén, Magnus |
| Copyright Year | 2006 |
| Abstract | Two novel processes for H2 production by reforming of fossil fuels with CO2 capture are examined. Both processes utilize the principles of chemical-looping combustion, which is an innovative combustion technology that can be used for CO2 capture in power generating processes. In chemical-looping combustion, direct contact between fuel and combustion air is avoided. Instead, a solid oxygen carrier performs the task of bringing oxygen from the air to the fuel. Thus, the resulting CO2 is not diluted with N2 and can easily be recovered. Chemical-looping reforming is basically a process for partial oxidation of hydrocarbon fuel, where chemical looping is used as a source of undiluted oxygen. Chemical-looping reforming has been demonstrated in a laboratory reactor consisting of two interconnected fluidized beds. Particles of NiO and MgAl2O4 were used as bed material and oxygen carrier. Natural gas was used as fuel. The reactor temperature was 820-930 oC. In the fuel reactor the oxygen carrier was reduced by the fuel, which in turn was partially oxidized to H2, CO, CO2 and H2O. In the air reactor the oxygen carrier was reoxidized with air. H2 production by chemical-looping reforming with CO2 capture has also been examined in a process study in which it was found that an overall reformer efficiency of 81%, including CO2 capture and CO2 compression, is possible. To obtain such high efficiency the whole system would need to be pressurized and integrated with a gas turbine. Steam reforming of natural gas with CO2 capture by chemical-looping combustion resembles conventional steam reforming, but the reformer furnace is replaced by chemical-looping combustion. Instead, reforming takes place in reactor tubes located inside the chemical looping fuel reactor. Energy for the endothermic reforming reactions is provided by fluidized bed heat exchange. Steam reforming with CO2 capture by chemical-looping combustion has been examined in a process study. It was found that CO2 for sequestration could be obtained without efficiency penalty and that the selectivity for H2 could be improved compared to conventional steam reforming due to low reactor temperature and more favorable heat-transfer conditions. The overall reformer efficiency could be 80% or higher, including CO2 capture and CO2 compression. Additionally, a model describing one single reformer tube surrounded by a fluidized bed was made to check the feasibility of the concept. The two models were combined and used to make a tentative reactor design. Reactor dimensions, particle flows, gas flows, pressure drops, heat transfer operations and temperature levels all seemed reasonable. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://publications.lib.chalmers.se/records/fulltext/24766.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
