Kinetic characteristics of micro-particle impact on a flat surface under humidity conditions

doi:10.11949/0438-1157.20211611

Abstract

Abstract:

Conventional dust removal device has a penetration window for the particles from coal combustion. The dust removing efficiency of wet electro-static precipitator could be improved by increasing the relative humidity (RH). The efficiency is different in coal and RH. The experimental facility and kinetic model for different fly ash particles against a flat surface under humid conditions were built to explore the variation of restitution coefficient. The results show that the coefficient of restitution of anthracite is the smallest under 65% RH, and it is easy to capture. With the increase of RH, the capillary force is dominant, and the damping coefficient, critical impact velocity and contact time increase.

Key words: coal combustion, humidification, particle, relative humidity, restitution coefficient, capillary force

摘要：

传统除尘装置对煤燃烧排放的颗粒物存在穿透窗口，湿式静电除尘器通过喷水增湿能够显著提高其脱除效率。对于不同煤种和湿度，脱除效率存在差异。因此搭建潮湿环境下不同飞灰颗粒撞击平板实验台并建立颗粒碰撞动力学模型，探究恢复系数的变化规律。结果表明，65%湿度下无烟煤的恢复系数最小，易于捕集；随着相对湿度增加，毛细力占主导，阻尼系数、临界捕集速度和接触时间增加。

关键词: 煤燃烧, 增湿, 粒子, 相对湿度, 恢复系数, 毛细力

CLC Number:

TQ 534.9

Xue LI, Ming DONG, Huang ZHANG, Jun XIE. Kinetic characteristics of micro-particle impact on a flat surface under humidity conditions[J]. CIESC Journal, 2022, 73(5): 1940-1946.

李雪, 东明, 张璜, 谢俊. 潮湿环境下微尺度颗粒撞击平板的动力学研究[J]. 化工学报, 2022, 73(5): 1940-1946.

Figures/Tables 10

Fig.1 Schematic diagram of the experimental system

Table 1 Total elemental analysis of fly ash particles

飞灰	含量/%
飞灰	SiO₂	Al₂O₃	CaO	MgO	TiO₂	SO₃	P₂O₅	Na₂O	Fe₂O₃	其他
NM	28.20	12.30	26.50	1.82	0.30	9.51	0.01	2.48	9.10	9.78
LN	52.30	36.40	2.39	0.63	2.84	2.08	1.42	0.56	0	1.38
XJ	14.30	15.70	23.40	9.00	0.60	17.2	0.13	4.82	12.4	2.45

Table 2 Physical parameters of fly ash particles

飞灰	密度/（kg/m³）	杨氏模量/GPa
NM	2815.46	140.61
LN	2680.25	115.93
XJ	2953.56	138.69

Fig.2 Size distribution of fly ash particle

Fig.3 Schematic of contact model between particle and flat

Fig.4 Normal restitution coefficient under dry and humid conditions

Fig.5 Adhesion force versus separation

Fig.6 Damping coefficient versus incident velocity

Table 3 Critical values of impact velocity in different conditions

飞灰

干燥

临界捕集速度/（m/s）

65%湿度

临界捕集速度/（m/s）

Fig.7 Incident time and rebound time of fly ash particles

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