Unmixed combustion: an alternative to fire

Lyon, Richard K.; Cole, Jerald A.

doi:10.1016/s0010-2180(99)00136-4

Cited by 177 publications

(133 citation statements)

References 4 publications

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“…Previously a 1:4 ratio of Ni to Ca was used to attain autothermal behaviour for methane unmixed reforming (Lyon and Cole, 2000), using calcined dolomite as the sorbent material.…”

Section: Resultsmentioning

confidence: 99%

“…With carefully chosen feed flows and durations, as well as the right OTM to CO 2 -sorbent ratio, Lyon and Cole (2000) demonstrated that the process could run autothermally, ie., without external heating and in a stable manner. When in autothermal operation, the reactor temperature oscillates during each cycle, with the lowest temperatures during fuel-steam feed and the highest at air feed, this in turn affects slightly the purity of the H 2 rich stream.…”

Section: Figure 1 Herementioning

confidence: 99%

“…Unmixed steam reforming, henceforth called 'USR', first appeared in the mainstream scientific literature through the two publications Kumar et al (1999) and Lyon and Cole (2000). It offers an alternative method for the autothermal production of a hydrogen-rich reformate (more than 90% dry).…”

mentioning

confidence: 99%

“…Alternative ways of continuously producing H 2 with a single reactor could also involve the use of a rotating bed travelling through air feed then fuel-steam feed zones. Unmixed steam reforming has previously been demonstrated using methane and diesel fuels (Kumar et al, 1999, andCole, 2000). Over subsequent years, DOE reports and conference presentations appeared in the literature as research and development continued from the original work and the terminology of autothermal cyclic reforming (Kumar et al, 2004), as well as unmixed fuel processing were also used in this context (Zamansky, 2002, Rizeq et al, 2003.…”

mentioning

confidence: 99%

“…90% dry H 2 ) with a single reactor, (ii) potential for autothermal operation without the need for pure oxygen that would require a costly air separator pre-processing stage, (iii) improved heat transfer characteristics that allow down-scaling up of the process to a point, increasing its potential for distributed power generation if coupled with an intermediate temperature solid oxide fuel cell, or with a molten carbonate fuel cell, (iv) low cost reactor materials due to a hotter reactor center and colder walls, (v) compactness of the process due to coupling of the endothermic and exothermic reactions within the reactor rather than relying on external heating, (vi) separation of CO 2 -containing effluent from the H 2 -rich reformate with potential for cheaper purification downstream technologies, (vii) insensitivity to coking, (viii) insensitivity to sulphur (as claimed by Lyon and Cole, 2000), finally, and related to the last two points, (ix) fuel feedstock-flexibility (gas and liquid). Currently there are adaptations of the principle of USR to pulverised coal using circulating fluidised beds technology which draw similarities with chemical looping combustion (Rizeq et al, 2003).…”

mentioning

confidence: 99%

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Production of hydrogen by unmixed steam reforming of methane

Dupont

Ross

Knight

et al. 2008

Chemical Engineering Science

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Unmixed steam reforming is an alternative method of catalytic steam reforming that uses separate air and fuel-steam feeds, producing a reformate high in H 2 content using a single reactor and a variety of fuels. It claims insensitivity to carbon formation and can operate autothermally. The high H 2 content is achieved by in-situ N 2 separation from the air using an oxygen transfer material (OTM), and by CO 2 capture using a solid sorbent. The OTM and CO 2 sorbent are regenerated during the fuel-steam feed and the air feed respectively within the same reactor. This paper describes the steps taken to choose a suitable CO 2 -sorbent material for this process when using methane fuel with the help of micro reactor tests, and the study of the carbonation efficiency and regeneration ability of the materials tested. Elemental balances from bench scale experiments using the best OTM in the absence of the CO 2 sorbent allow identifying the sequence of the chemical reaction mechanism. The effect of reactor temperature between 600 and 800°C on the process outputs is investigated. Temperatures of 600°C and 800°C under the fuel-steam feed were each found to offer a different set of desirable outputs. Two stages during the fuel-steam feed were characterised by a different set of global reactions, an initial stage where the OTM is reduced directly by methane, and indirectly by hydrogen produced by methane thermal decomposition, in the second stage, steam reforming takes over once sufficient OTM has been reduced. The implications of these stages on the process desirable outputs such as efficiency of reactants conversion, reformate gas quality, and transient effects are discussed.

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“…Previously a 1:4 ratio of Ni to Ca was used to attain autothermal behaviour for methane unmixed reforming (Lyon and Cole, 2000), using calcined dolomite as the sorbent material.…”

Section: Resultsmentioning

confidence: 99%

Section: Figure 1 Herementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Production of hydrogen by unmixed steam reforming of methane

Dupont

Ross

Knight

et al. 2008

Chemical Engineering Science

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Chemical Looping Combustion and Gasification

Fan

Chung

Bayham

et al. 2015

Handbook of Clean Energy Systems

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With the emerging challenge of climate change and the continued escalation of energy demands, innovative and flexible fuel conversion technologies are necessary and gaining recognition. Chemical looping technologies have the potential to not only reduce energy costs, but also to mitigate carbon emissions. Historically, the general concept of this reduction–oxidation mechanism has been suggested, but the process was never commercialized. Recent interests in carbon capture techniques have revitalized the adaptive chemical looping system. Chemical looping technologies can utilize both gaseous and solid fuels such as natural gas and coal, respectively, for power, hydrogen, or chemical generation. However, the success of technological adoption requires a thorough understanding of the types of chemical looping techniques, the design considerations, and the reactor modes of configurations. Current large‐scale testing units are examined with the hope for near‐term advancement and future commercial application.

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Oxygen Carriers for Chemical‐Looping with Oxygen Uncoupling (CLOU)

Mattisson

Whitty

2018

Handbook of Chemical Looping Technology

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Unmixed combustion: an alternative to fire

Cited by 177 publications

References 4 publications

Production of hydrogen by unmixed steam reforming of methane

Production of hydrogen by unmixed steam reforming of methane

Chemical Looping Combustion and Gasification

Oxygen Carriers for Chemical‐Looping with Oxygen Uncoupling (CLOU)

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