燃煤飞灰粒度对比电阻影响机制的试验研究

An Experimental Study of the Mechanism Governing the Impact of the Size of Coal-fired Fly Ash Particle on Specific Resistance

通过采集国内3家电厂的灰样，在高温炉中全灰化后，采用机械筛分法将其筛分为〉154μm、90～154μm、45～90μm和〈45μm4种粒度的灰样，利用自主研发的DR型高压粉尘比电阻试验台测定各粒径飞灰的比电阻。结果发现，由于表面导电和容积导电共同影响飞灰的比电阻，并且细颗粒具有更高的孔隙率，所以粒径较细的飞灰比电阻峰值较高，且比电阻达到峰值以前，灰样越粗则比电阻越高，在比电阻达到峰值后，则规律恰好相反。

After the ash samples have been collected from three domestic power plants and fully incinerated in a high temperature furnace,they were sifted by employing a mechanical sifting method into four categories of particle diameters,i.e.>145 μm,90～154 μm,45～90 μm and <45 μm.On a self-developed DR type high-pressure dust specific-resistance test rig,the specific resistance of fly ash of various particle diameters were determined.The test results show that superficial and volumetric electric conduction will jointly affect the specific resistance of fly ash and,furthermore,fine particles have a higher porosity.As a result,the fly ash with relatively small particle diameters has a higher peak value of specific resistance Moreover,before the latter reaches its peak value,the more coarse the ash samples,the higher their specific resistance.After the specific resistance has reached its peak value,however,the governing rule will evolve in an exactly opposite way.