Temperature
showed obvious effect on the reaction rate and conversion
when CuO was used as an oxygen carrier (OC), in which in situ gasification
chemical-looping combustion (iG-CLC) occurred at low temperature and
in situ gasification chemical-looping with oxygen uncoupling (iG-CLOU)
took place at high temperature. This study focused on the reaction
mechanism investigation of the coal iG-CLC and iG-CLOU process. The
reaction mechanism and definite temperature limits between iG-CLC
and iG-CLOU could provide useful information for the development of
mixed CuO-based OCs. In this study, the experiments of coal with CuO
were tested in N2 and CO2 atmospheres. Results
showed that char was mainly oxidized by CuO in the temperature range
of 620–810 °C in a N2 atmosphere. Chemical-looping
combustion changed into chemical-looping with oxygen uncoupling, in
which the reaction of char with gaseous oxygen was dominated when
temperature was above 810 °C. Under a CO2 atmosphere,
the initial temperature of char combustion was still 620 °C,
but the reaction path of char combustion changed. From about 746 °C,
char could be gasified by CO2 first, and then the gasification
product was oxidized by CuO. With the temperature increased to 775
°C, the oxygen released from CuO led to the reaction rate increasing.
Char could be gasified by CO2, and then the gasification
product preferentially reacted with gaseous oxygen. Moreover, char
gasification was also the rate-limiting step in the iG-CLOU process.
Considering the reactivity and stability of CuO, alkali metals and
alkaline earth metals with low content and inert support that could
improve the high temperature resistance should be used as modifications
of CuO in the iG-CLOU process.
Abstract. The pyrolysis gasification treatment in the paper is the new direction of municipal solid waste disposal by comparing waste incineration, composting and sanitary landfill treatment technology. The principle and classification of pyrolysis gasification technology are described in detail. The research status of three typical commercial waste disposal devices and pyrolysis gasification of domestic waste are introduced. The pyrolysis gasification temperature of waste is suitable between 700~900 ℃, the increase of gasification temperature can increase the yield and low calorific value of synthesis gas. Adding proper amount of water vapor to the gasification medium facilitates the cracking of the tar and improves the H2 content in the synthesis gas.
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