Impact of the Circulating Fluidized Bed Riser on the Performance of a Loopseal Nonmechanical Valve
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- 作者：Esmail R. Monazam ; Lawrence J. Shadle ; Joseph S. Mei
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2007
- 出版时间：March 14, 2007
- 年：2007
- 卷：46
- 期：6
- 页码：1843 - 1850
- 全文大小：172K
- 年卷期：v.46,no.6(March 14, 2007)
- ISSN：1520-5045
文摘
Most advanced coal-fuel power systems require the transfer and control of solids between two or more vessels.In many instances, the key to a successful process operation is how well the solids transfer and controlsystem has been designed. This is particularly true in a transport gasifier and circulating fluidized bed (CFB)combustors, which are dependent upon the rapid and reliable circulation of solids to maintain a constantsolids concentration in the CFB. Proper design and operation of solids returning systems are essential to theperformance and operation of CFB combustion systems. An experimental investigation was conducted at theNational Energy Technology Laboratory (NETL) of the U.S. Department of Energy (DOE) to study the flowand control of a light material (cork), which has a particle density of 189 kg/m3 and a mean diameter of 812
m, through a nonmechanical valve, or loopseal, in a 0.3 m diameter CFB cold model. Fluidizing this materialin ambient air approximates the same gas:solids density ratio as coal and coal char in a pressurized gasifier.The loopseal is composed of the lower section of the standpipe, an upward-flowing fluidized-bed section,and a downwardly angled overflow tube which is connected to the desired return point at the bottom of theriser. In the nonmechanical valve, both the standpipe and the fluidized-bed up-flow section of the loopsealwere aerated and fluidized with air, respectively. The objective of this study was to investigate the effects ofstandpipe aeration, loopseal aeration, solids inventory, and superficial gas velocity through the riser on theflow rate of circulating solids. A correlation that predicts the solids flow rate as a function of these variableswas developed. Comparison of the correlation with the experimental data is discussed. Pressure drop acrossthe fluidized-bed up-flow section of the loopseal was found to increase slightly with the solid flow rates.
m, through a nonmechanical valve, or loopseal, in a 0.3 m diameter CFB cold model. Fluidizing this materialin ambient air approximates the same gas:solids density ratio as coal and coal char in a pressurized gasifier.The loopseal is composed of the lower section of the standpipe, an upward-flowing fluidized-bed section,and a downwardly angled overflow tube which is connected to the desired return point at the bottom of theriser. In the nonmechanical valve, both the standpipe and the fluidized-bed up-flow section of the loopsealwere aerated and fluidized with air, respectively. The objective of this study was to investigate the effects ofstandpipe aeration, loopseal aeration, solids inventory, and superficial gas velocity through the riser on theflow rate of circulating solids. A correlation that predicts the solids flow rate as a function of these variableswas developed. Comparison of the correlation with the experimental data is discussed. Pressure drop acrossthe fluidized-bed up-flow section of the loopseal was found to increase slightly with the solid flow rates.