高压浓相变粒径煤粉气力输送阻力特性

Resistance characteristics of dense-phase pneumatic conveying pulverized coal with various particle size under high pressure

在自主设计的高压浓相气力输送系统上进行不同粒径的煤粉气力输送试验研究.在对试验系统进行准确性和稳定性分析的基础上,分别在不同的输送压力、煤粉粒径和输送速度等条件下进行输送试验,考察操作参数和煤粉物性对各管段的压损、局部阻力特性及输送气体品质的影响规律.结果表明:随着输送速度的增加,各管段压损先减小后略有增大;在相同的质量流量和输送压力下,随着煤粉平均粒径的增大,压损逐渐增大.在输送速度和固气比保持不变的条件下,随着压力的升高,输送气体的输送能力增强,压损逐渐降低,ΔPv-ΔPh逐渐减小.随着表观速度的增加,弯管局部阻力先减小后变化平缓;在相同表观速度下,煤粉粒度越大,局部阻力值越高;弯管当量系数K与输送速度、固气比无关,与煤粉粒径,输送压力相关;随着粒径的增加,弯管当量系数K先增大后减小.

Dense-phase pneumatic conveying experiments of pulverized coal with various particle sizes were carried out at the experimental facility. Based on analyzing the stability and accuracy of experimental system, the influences of the conveying pressure, the coal particle sizes and the conveying velocity on pressure drops of different pipe sections, local pressure drop characteristics and quality of conveying gas were investigated. The results indicate that pressure drops of different pipe sections increase first and then decrease with the increase in conveying velocity. Under a constant mass flow rate and conveying pressure, the larger the mean coal particle sizes are, the greater the pressure drops are. Gas conveying capacity rises but pressure drops and △Pv - △Ph decreases with the increase in conveying pressure at the constant solid-gas ratio and conveying velocity. Local pressure drop of bend pipe reduces first and then remains nearly flat with the increase in superficial velocity. There are positive correlations between coal particle size and local pressure drop. The bend equivalent coefficient K which does not relate to the conveying velocity and the solid-gas ratio is affected by the coal particle size and the conveying pressure. The bend equivalent coefficient K increases first and then decreases with the increase in coal particle size.