Effect of feeding gas on pneumatic conveying of pulverized coal in industrial-scale vertical pipe

doi:10.11949/j.issn.0438-1157.20151094

Abstract

Abstract:

The dense-phase pneumatic conveying of pulverized coal was investigated in an industrial-scale vertical pipe (50 mm I.D.). Air and CO₂ was used as feeding gas or carrying gas, which consequently forms four typical cases, namely Air→Air, Air→CO₂, CO₂→Air and CO₂→CO₂. Comparison was conducted between the above cases to analyze the conveying characteristics of pulverized coal experienced different courses. The results showed that the compound modes of feeding gas and carrying gas could affect the fluidized state of pulverized coal in the feeder vessel and result in the differences of stability and flow patterns of conveying process. Electrical capacitance tomography (ECT) was employed to monitor the flow patterns, while the solid concentration signals obtained from ECT were analyzed on the basis of standard deviation (SD) function and power spectral density (PSD) function. It was concluded that the flow pattern of pulverized coal in the case of Air→Air was a stable annular flow, and the stability of the case of Air→CO₂was the worst in which the flow pattern changed from a stable flow to slug flow. Both cases of CO₂→Air and CO₂→CO₂ performed plug flow. In comparison, in the case of CO₂→CO₂, the bigger plug and higher peak value of PSD were obtained.

Key words: gas switching, stability, CO₂, pneumatic conveying, ECT

摘要：

采用Air和CO₂作为供料和输送载气,以工业级竖直上升管(内径50 mm)粉煤输送系统为实验平台,开展了粉煤密相气力输送实验研究。实验中选用Air→Air、Air→CO₂、CO₂→Air和CO₂→CO₂作为典型工况,进行了输送特性参数的对比分析。研究结果表明,供料载气与输送载气组合方式的变化,会引起发料罐中粉煤流化状态的改变,进而导致粉煤输送流型和稳定性方面的差异。借助电容层析成像系统(ECT)获得了竖直管的ECT信号和流型图像,并采用标准差和功率谱函数对ECT信号进行分析。分析结果表明,Air→Air工况为稳定的环状流;Air→CO₂输送过程稳定性最差,输送由无定态流型转为栓塞流;CO₂→Air和CO₂→CO₂输送过程均为气栓流,但CO₂→CO₂工况形成的气栓较长,其ECT信号的功率谱峰值较大。

关键词: 载气切换, 稳定性, CO₂, 气力输送, ECT

CLC Number:

TQ022.3

PAN Xiangming, GUO Xiaolei, LU Haifeng, LIU Kai, FU Lin, LI Peng, GONG Xin. Effect of feeding gas on pneumatic conveying of pulverized coal in industrial-scale vertical pipe[J]. CIESC Journal, 2016, 67(4): 1169-1178.

潘响明, 郭晓镭, 陆海峰, 刘剀, 付琳, 李鹏, 龚欣. 不同载气供料对工业级竖直上升管粉煤气力输送的影响[J]. 化工学报, 2016, 67(4): 1169-1178.

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