2010 Fiscal Year Final Research Report
Study on Subcritical Wet Combustion
| Project/Area Number |
20560189
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Nagoya University |
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Principal Investigator |
HASEGAWA Tatsuya Nagoya University, エコトピア科学研究所, 教授 (40164818)
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| Project Period (FY) |
2008 – 2010
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| Keywords | 新エネルギー / 熱工学 / バイオマス / 湿式燃焼 / 亜臨界水 |
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| Research Abstract |
This study treated wet combustion of ethanol under three different subcritical conditions, i.e., low pressure hot water, high pressure hot water and high temperature steam.
Under the low pressure hot water condition (6 MPa, 200-260℃), supplied oxygen gas formed bubbles in the solution of ethanol. Thus it is necessary to control the diameter and the number of bubbles in the solution to enhance wet combustion by installing a metal filter with different pore sizes at the inlet of oxygen and by controlling the pressure and the mass flow rate of the oxygen. It was difficult to promote combustion with heat release nevertheless.
Under the high pressure hot water condition (25 MPa, 260-350℃), supplied hydrogenperoxide worked well as an oxidizer in liquid phase. However, the obtained conversion rate of ethanol was 10^<-6> times less than that obtained under supercritical conditions. The analyses of components during wet combustion proved that the wet oxidation of ethanol could be described by the
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consecutive network Ethanol→Acetaldehyde→Acetic acid→Carbon monoxide→Carbon dioxide.
Under the high temperature steam condition (10 MPa, 430-490℃), supplied hydrogenperoxide worked well as an oxidizer in gas phase. It is worth noting that the obtained conversion rate of ethanol was similar to that obtained under supercritical conditions. This means high temperature steam wet combustion is equivalen to the supercritical wet combustion without risk of safety and cost. Qualitative and quantitative analyses of products proved that liquid products were acetaldehyde and acetic acid and gas phase products were carbon monoxide, carbon dioxide, methane and ethane. The parallel reaction network of first order model well described the characteristics of the ethanol decomposition to acetaldehyde and acetic acid. Utilisation of high temperature steam can overcome the problem of pressure tightness of the reactor in Supercritical water oxidation and be utilised in practical facilities.
Last par of this study was numerical simulation of wet combustion. A simulation code available for oxidation of water solution mixture under sub/super critical conditions was developed. Lee-Kesler equation was selected as the equation of state for both sub/super critical conditions. The transport properties and thermal properties were derived by adopting mixing laws. Numerically simulated behaviors of wet combustion of ethanol under sub-/super critical conditions demonstrated experimental behavior of heat release.
Last par of this study was numerical simulation of wet combustion. A simulation code available for oxidation of water solution mixture under sub/super critical conditions was developed. Lee-Kesler equation was selected as the equation of state for both sub/super critical conditions. The transport properties and thermal properties were derived by adopting mixing laws. Numerically simulated behaviors of wet combustion of ethanol under sub-/super critical conditions demonstrated experimental behavior of heat release. Less
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Research Products
(13 results)
