Performance of Chinese Coals under Conditions Simulating Entrained-Flow Gasification
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- 作者：Baomin Wang ; Xiaoyu Li ; Shisen Xu ; N. Paterson ; D. R. Dugwell ; and R. Kandiyoti
- 刊名：Energy & Fuels
- 出版年：2005
- 出版时间：September 2005
- 年：2005
- 卷：19
- 期：5
- 页码：2006 - 2013
- 全文大小：170K
- 年卷期：v.19,no.5(September 2005)
- ISSN：1520-5029
文摘
A novel, two-stage entrained-flow gasifier is being developed by the Thermal Power ResearchInstitute in China. In the present work, the factors that affect the pyrolysis and gasificationreactivity of 14 potential coals for this plant have been studied, under conditions that simulatethe temperature, pressure, and particle heating rates in the proposed gasifier. The work wasperformed using a high-temperature, high-pressure, variable-heating-rate wire-mesh apparatus(2000 
C, 3.0 MPa). The trends in reactivity, measured for three of the coals at laboratory scale,and a 20-kg/h (small) pilot plant in China were similar. The use of the wire mesh reactor (WMR),coupled with a residual char reactivity measurement, using a thermogravimetric analyzer, hasproved useful in characterizing coals selected for entrained-flow gasification. The data haveallowed the comparison of reactivities within the suite of coals. The results showed a generaltrend of declining reactivity with increasing rank. However, the scatter in the data, as in mostsuch cases, does not allow the construction of simple correlations to help predict the performanceof individual coals; therefore, the reactivities of individual coals must be evaluated experimentally.The pilot gasifier that is under construction is intended to achieve almost-complete conversionof the coal injected into both stages. The results suggest that overall conversions in the high-temperature first stage of the reactor will be only marginally sensitive to sample reactivity.However, the second stage of the pilot reactor is expected to give an exit gas temperature of~900 C. It is likely that the reactivity of the coals injected into the second stage will have agreater effect on achieving the desired high conversions. The ash melting temperature and slagviscosity for the same suite of coals have been assessed using existing mathematical models,which were primarily developed for combustion-based applications. This has shown that the ashand slag properties will vary widely, depending on the composition of the ash. Unsuccessfulattempts were made to measure the viscosity of a slag sample from a pilot-scale gasifier in Chinaunder the appropriate conditions. However, the work has highlighted the difficulties involved inmaking valid measurements for gasifier slags, which should help to guide future work.
C, 3.0 MPa). The trends in reactivity, measured for three of the coals at laboratory scale,and a 20-kg/h (small) pilot plant in China were similar. The use of the wire mesh reactor (WMR),coupled with a residual char reactivity measurement, using a thermogravimetric analyzer, hasproved useful in characterizing coals selected for entrained-flow gasification. The data haveallowed the comparison of reactivities within the suite of coals. The results showed a generaltrend of declining reactivity with increasing rank. However, the scatter in the data, as in mostsuch cases, does not allow the construction of simple correlations to help predict the performanceof individual coals; therefore, the reactivities of individual coals must be evaluated experimentally.The pilot gasifier that is under construction is intended to achieve almost-complete conversionof the coal injected into both stages. The results suggest that overall conversions in the high-temperature first stage of the reactor will be only marginally sensitive to sample reactivity.However, the second stage of the pilot reactor is expected to give an exit gas temperature of~900 C. It is likely that the reactivity of the coals injected into the second stage will have agreater effect on achieving the desired high conversions. The ash melting temperature and slagviscosity for the same suite of coals have been assessed using existing mathematical models,which were primarily developed for combustion-based applications. This has shown that the ashand slag properties will vary widely, depending on the composition of the ash. Unsuccessfulattempts were made to measure the viscosity of a slag sample from a pilot-scale gasifier in Chinaunder the appropriate conditions. However, the work has highlighted the difficulties involved inmaking valid measurements for gasifier slags, which should help to guide future work.