流化床换热用PTFE／SiO2固体颗粒的制备及性能

Preparation and Properties of PTFE/SiO_2 Solid Particles Used in Fluidized Bed Heat Exchanger

综合考虑二氧化硅(Si O2)微粉和聚四氟乙烯(PTFE)的优良特性,在PTFE粉末中添加不同含量的Si O2,对其进行填充改性,采用糊膏挤出方式,制备不同Si O2含量的复合型PTFE/Si O2惰性固体颗粒,考察了Si O2含量对PTFE密度、硬度和摩擦磨损性能的影响,并将复合固体颗粒应用于汽–液–固三相循环流化床换热器,进一步研究不同Si O2含量下复合固体颗粒的传热性能。结果表明,在PTFE中添加Si O2能显著提高PTFE的密度和硬度,降低PTFE的摩擦系数和磨痕宽度;在Si O2质量分数为12%时,将制成的复合固体颗粒应用于循环流化床换热器中,能够使其膜传热系数相比添加纯PTFE颗粒的增加4.7%,强化传热效果最好;适宜加入流化床换热器的复合固体颗粒体积分数为4%。

Considering the excellent characteristics of silica（SiO2） and polytetrafluoroethylene（PTFE）, adding different content of SiO2 in PTFE powder by filling modification and adopting paste extrusion method, composite PTFE / SiO2 inert solid particles with different SiO2 content were prepared. The effects of SiO2 content on the density, hardness, friction and wear properties of the solid particles were investigated, and the solid particles were applied to the vapor-liquid-solid three-phase circulating fluidized bed heat exchanger, the heat transfer properties of the solid particles with different SiO2 content were further studied. Experiment results show that adding SiO2 in PTFE can significantly increase the density and hardness, reduce the friction coefficient and wear width of PTFE. When the mass fraction of SiO2 is 12%, the composite solid particles used in circulating fluidized bed heat exchanger can make the film heat transfer coefficient increasing by 4.7% comparing with that of pure PTFE solid particles, the heat transfer effect is best. Suitable volume fraction of the composite solid particles adding in fluidized bed heat exchanger is 4%.