复杂流道结构料仓的下料流率预测

doi:10.11949/0438-1157.20190867

摘要/Abstract

摘要：

在实验室搭建的有机玻璃料仓下料平台上，分别以自由流动粉体玻璃微珠和黏附性粉体煤粉和聚氯乙烯为实验介质，针对无改流体(No-In)、封闭改流体(Con-In)和开放改流体(Ucon-In)三种情况所形成的不同流道结构，开展了粉体料仓下料及其流率建模研究，定量分析了改流体对粉体下料流率的促进作用，对比给出了玻璃微珠、煤粉和聚氯乙烯在不同流道结构料仓内的下料特性。研究表明，改流体的引入有利于提高料仓下料流率，Con-In促进流动效果最明显，对于流动性弱的煤粉，下料流率提升幅度达到最大的58%。基于剪切摩擦区的概念，提出流率校正因子F对最小能量理论方程进行了修正，将理想的料仓下料模型拓展至实际下料过程。进一步，对于Con-In，根据流道结构特征结合对粉体的受力分析，修正了模型中的锥角项；对于Ucon-In，基于粉体下料流动竞争机制，提出分阶段下料模式并关联了内层和夹层的下料流率，最终建立了复杂流道结构料仓的下料流率预测模型。该模型综合考虑了粉体物性、下料流型和流道结构的影响，可有效预测自由流动粉体和黏附性粉体流经传统料仓(No-In)和改流体料仓(包括Con-In和Ucon-In)的粉体下料流率，且预测偏差<10%。

关键词: 粉体, 料仓, 下料流率, 流道结构, 改流体

Abstract:

By means of perspex hopper platform built in the laboratory, the flow behaviors of powders were investigated under the action of various flow channel structures in hoppers without insert (No-In), with confined insert (Con-In) and with unconfined insert (Ucon-In). Discharge experiments of free-flowing glass beads and adhesive pulverized coal and polyvinyl chloride were carried out and a model was established to predict the solid flow rate. The effects of inserts contributing to increasing the flow rate were analyzed quantitatively and the flow characteristics of glass beads, pulverized coal and polyvinyl chloride were compared considering distinct flow channel structures. The research shows that the introduction of the modified fluid is beneficial to increase the flow rate of the silo. Con-In promotes the most obvious flow effect. For the weak coal powder, the flow rate of the lower flow rate reaches the maximum of 58%. Based on the evolution of shear flow zone, a correction factorF was proposed to modify the minimum energy theory equation, and the model for ideal hoppers was extended to take effect under actual situations. Furthermore, regarding Con-In, according to the structural characteristics of the flow channels and the force analysis on powders, the term relating to conical angle in the model was modified. In terms of Ucon-In, based on the competition mechanism, a specific flow sequence during discharge was proposed and the relationship between flow rate of inner layer and that of interlayer was obtained. Finally, a model to predict the solid flow rate in hopper with complicated flow channel structures was established. The model took into account the effects of powder properties, flow patterns and structural parameters, which can effectively predict the discharge rate of free-flowing and adhesive powders flowing through traditional hoppers (No-In) and hoppers with insert (including Con-In and Ucon-In) with the deviation less than 10%.

Key words: powders, hoppers, discharge rate, flow channel structure, inserts

中图分类号:

TQ 536

孙栋, 陆海峰, 曹嘉琨, 吴雨婷, 郭晓镭, 龚欣. 复杂流道结构料仓的下料流率预测[J]. 化工学报, 2020, 71(3): 974-982.

Dong SUN, Haifeng LU, Jiakun CAO, Yuting WU, Xiaolei GUO, Xin GONG. Solid flow rate prediction in hoppers with complicated flow channels[J]. CIESC Journal, 2020, 71(3): 974-982.

图/表 19

图1 粒径累积分布

Fig.1 Accumulative particle size distribution

表1 物性数据

Table 1 Physical properties of experimental materials

Material	d₃₂/μm	d₄₃/μm	Span	ρ_b/(kg·m^-3)	AOR/(°)	AIF/(°)
glass bead-a	47.22	49.43	0.56	1410	28.8	19.8
glass bead-b	62.76	65.13	0.51	1404	28.3	21.2
glass bead-c	75.84	120.14	0.90	1353	34.6	32.7
lignite	115.63	134.12	0.88	621	36.7	28.7
pvc	116.36	128.61	0.73	567	34.0	26.5

图2 下料实验装置

Fig.2 Diagram of discharge device

图3 设备尺寸参数

Fig.3 Device parameters

图4 下料操作模式(阴影部分为非流动区)

Fig.4 Discharge operation modes (hatched domain is not available for flow)

图5 下料流动顺序

Fig.5 Diagram of sequential flow order during discharge

表2 下料流率实验值

Table 2 Experimental value of discharge rate

Material	No-In /(g·s^-1)	Con-In/ (g·s^-1)	Ucon-In /(g·s^-1)
glass bead-a	45.0	53.2	52.1
glass bead-b	46.7	54.2	48.4
glass bead-c	38.8	48.7	43.0
lignite	13.8	21.7	18.1
pvc	13.7	16.7	15.1

图6 流道结构对下料流率提升幅度的影响

Fig.6 Relationship between increase of discharge rate and flow channel structure

图7 坐标轴系统结构

Fig.7 Schematic diagram of coordinate system

表3 No-In下料模式下实验值与预测值的偏差

Table 3 Deviation between experimental value and theoretical value under No-In mode

Material	Experiments/(g·s^-1)	Eq. (1)/(g·s^-1)	Eq. (3)/(g·s^-1)	\|RE\| of Eq. (1)/%	\|RE\| of Eq. (3)/%
glass bead-a	45.0	52.9	45.3	14.9	0.7
glass bead-b	46.7	52.6	44.3	11.2	5.4
glass bead-c	38.8	49.7	34.7	21.9	11.7
lignite	13.8	22.9	17.3	39.7	20.6
pvc	13.7	20.9	16.4	34.4	16.5

图8 下料过程物料自由表面的变化[6]

Fig.8 Free surface during powder discharge process[6]

图9 玻璃微珠的下料过程

Fig.9 Diagram of discharge of glass bead

图10 实验值与预测值的比较

Fig.10 Comparison of experiment and model values of discharge rate

图11 流动区域转变示意图

Fig.11 Schematic diagram of flow zones transition

图12 Con-In作用下粉体受力示意图

Fig.12 Schematic diagram of force analysis of powders under Con-In

表4 Con-In下料模式下实验值与预测值的偏差

Table 4 Deviation between experimental value and theoretical value under Con-In mode

Material	Experiments/(g·s^-1)	Eq. (10)/(g·s^-1)	\|RE\| of Eq. (10)
glass bead-a	53.2	61	12.80%
glass bead-b	54.2	59.6	9.10%
glass bead-c	48.7	46.7	4.20%
lignite	21.7	23.3	6.80%
pvc	16.7	22	24.10%

图13 Ucon-In作用下的瞬时流率

Fig.13 Diagram of variation of sample instantaneous discharge rate with time in silo with unconfined insert

图14 两个阶段下料流率的关系

Fig.14 Relationship of discharge rate between two stages

图15 实验值与预测值的比较

Fig.15 Comparison of experiment and model values of discharge rate

参考文献 30

1	Lu H,Guo X,Jin Y,et al.Powder discharge from a hopper-standpipe system modelled with CPFD[J].Advanced Powder Technology,2017,28(2):481-490.
2	Lu H,Guo X,Gong X,et al.Experimental study on aerated discharge of pulverized coal[J].Chemical Engineering Science,2012,71(13):438-448.
3	Liu P,Lamarche C Q,Kellogg K M,et al.Cohesive grains: bridging micro-level measurements to macro-level flow behaviorvia surface roughness[J].AIChE Journal,2016,62(10):3529-3537.
4	Lu H,Zhong J,Cao G P,et al.Gravitational discharge of fine dry powders with asperities from a conical hopper[J].AIChE Journal,2018,64(2):427-436.
5	Zhao Y,Yang S,Zhang L,et al.DEM study on the discharge characteristics of lognormal particle size distributions from a conical hopper[J].AIChE Journal,2018,64(4):1174-1190.
6	Freyssingeas E,Dalbe M J,Géminard J C.Flowers in flour: avalanches in cohesive granular matter[J].Physical Review E,2011,83(5):051307.
7	Jaeger H M,Nagel S R,Behringer R P.Granular solids, liquids, and gases[J].Reviews of Modern Physics,1996,68(4):1259-1273.
8	孙其诚,王光谦.静态堆积颗粒中的力链分布[J].物理学报,2008,57(8):4667-4674.
	Sun Q C,Wang G Q.Force distribution in static granular matter in two dimensions[J].Acta Physica Sinica,2008,57(8):4667-4674.
9	Campbell C S.Granular material flows – an overview[J].Powder Technology,2006,162(3):208-229.
10	Zheng Q J,Xia B S,Pan R H,et al.Prediction of mass discharge rate in conical hoppers using elastoplastic model[J].Powder Technology,2017,307:63-72.
11	Zhu H,Zhou Z,Yang R,et al.Discrete particle simulation of particulate systems: a review of major applications and findings[J].Chemical Engineering Science,2008,63(23):5728-5770.
12	Zhao Y,Cocco R A,Yang S,et al.DEM study on the effect of particle-size distribution on jamming in a 3D conical hopper[J].AIChE Journal,2019,65(2):512-519.
13	陆海峰,郭晓镭,陶顺龙,等.不同载气供料对煤粉料仓下料的影响[J].化工学报,2014,65(9):3383-3388.
	Lu H F,Guo X L,Tao S L,et al.Effect of feeding gas on hopper discharge of pulverized coal[J].CIESC Journal,2014,65(9):3383-3388.
14	Jasion G T,Shrimpton J S,Li Z,et al.On the bridging mechanism in vibration controlled dispensing of pharmaceutical powders from a micro hopper[J].Powder Technology,2013,249:24-37.
15	Zhang C,Qiu C,Pu C,et al.The mechanism of vibrations-aided gravitational flow with overhanging style in hopper[J].Powder Technology,2018,327:291-302.
16	Yang S C,Hsiau S S.The simulation and experimental study of granular materials discharged from a silo with the placement of inserts[J].Powder Technology,2001,120(3):244-255.
17	Zhang Q,Hao B,Britton M G.Flow patterns of cohesive feed in a model bin with flow-corrective inserts[J].Canadian Biosystems Engineering,2002,44(2):5.1-5.6.
18	Lu H,Guo X,Gong X,et al.Prediction of solid discharge rates of pulverized coal from an aerated hopper[J].Powder Technology,2015,286:645-653.
19	Matchett A J.A theoretical model of vibrationally induced flow in conical hopper systems[J].Chemical Engineering Research and Design,2004,82(1):85-98.
20	Härtl J.A study of granular solids in silos with and without an insert[D].Edinburgh:The University of Edinburgh,2008.
21	Wójcik M,Tejchman J,Enstad G G.Confined granular flow in silos with inserts — full-scale experiments[J].Powder Technology,2012,222:15-36.
22	Beverloo W A,Leniger H A,Velde J V D.The flow of granular solids through orifices[J].Chemical Engineering Science,1961,15(3):260-269.
23	Tierrie J,Baaj H,Darmedru P.Modeling the relationship between the shape and flowing characteristics of processed sands[J].Construction and Building Materials,2016,104:235-246.
24	Khashayar S,Shahab G,Reza Z.A review on gravity flow of free-flowing granular solids in silos - basics and practical aspects[J].Chemical Engineering Science,2018,192:1011-1035.
25	Rose H F,Tanaka T.Rate of discharge of granular materials from bins and hoppers[J].The Engineer,1959,208:465-469.
26	Carleton A J.The effect of fluid-drag forces on the discharge of free-flowing solids from hoppers[J].Powder Technology,1972,6(2):91-96.
27	Brown R L,Richards J C.Profiles of flow of granules through apertures[J].Transactions of the Institute of Chemical Engineers,1960,38:243-256.
28	Verghese T M,Nedderman R M.The discharge of fine sands from conical hoppers[J].Chemical Engineering Science,1995,50(50):3143-3153.
29	Gentzler M,Tardos G I.Measurement of velocity and density profiles in discharging conical hoppers by NMR imaging[J].Chemical Engineering Science,2009,64(22):4463-4469.
30	Liu Y,Guo X L,Lu H F,et al.An investigation of the effect of particle size on the flow behavior of pulverized coal[J].Powder Technology,2015,102:698-713.

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