Research On Improving The Slurryability Of Shenhua Coal By Particle Grading

Shenhua coal with the properties of low ash,low sulfur and low ash fusion temperture is an environmentally friendly coal and suitable for coal water slurry(CWS)gasification.However,it is difficult to prepare high-concentration coal water slurry in gasification process which is an very urgent and important problem to be solved.In order to increase the slurry concentration of Shenhua coal,TDH,SY2#and SH coal were selected to analysis the basic properties such as the proximate,ultimate,calorific and HGI analysis.A series of coarse particles(?74?m)and fine particles(<74?m)of SH coal were prepared through sieving and milling processes.The effect of coal particle size and coal particle content on the concentration and other properties of CWS was investigated.Based on the analysis of the peak type parameters of particle size,the relationship between the maximum concentration of the slurry and the bimodal spacing,the ratio of the bimodal area was studied.The sphericity of coal particles is introduced into the most tightly packed model to establish Simplified model of particle accumulation,and the scheme of particle grading is verified and optimized.Research shows that:The characteristics of the CWS were influenced significantly by the particle size distribution and the propotion of different coal particles,The coarse particles(250?425?m)and fine particles with D50(median diameter)at about 34.61?m were graded to prepare the CWS.The result showed that the highest concentration of the slurry firstly increased and then decreased with the propotion of particle size at 250-425?m increased gradually.When the mass ratio of coarse particles(250?425?m)to fine particles with D50 at about 34.61?m reached to 7:3,the maximum concentration of the slurry was 64.40%.Meanwhile,the coarse particles(?74?m)with different sizes and fine particles with D50 at about 34.61 ?n were graded at the mass ratio of 5:5,it could be found that the maximum concentration of the slurry decreases gradually with the decrease of the content of coarse particles size.When the mass ratio of coarse particles(74?150?m)to fine particles with D50 at about 34.61 ?m reached to 5:5,the maximum concentration of the slurry only as low as 60.40%.The experimental results suggested that the coarse particles were beneficial for reducing the viscosity of CWS and improving the fluidity of slurry,while fine particles were conducive to the stability of the CWS.The particle size distribution of coal particles presents unimodal,biomoal and trimodal peaks distribution,among which the spacing and the area ratio of biomoal peaks significantly affected the maximum concentration of CWS.As coarse particles(250?425?m)and fine particles with D50 at 34.5 ?m,22.74?m and 8.56?m were pulped at a mass ratio of 5:5,the maximum concentration of the slurry firstly increased and then decreased with the increase of the biomoal peaks spacing and the ratio of the bimodal peaks area.In addition,the performance of CWS with discontinuous biomoal peaks was better than that of continuous biomoal peaks.The simplified model of particle accumulation(dl means size of coarse particles,d2 and d3 refers to size of fine particle and super fine particles)was established by introduced sphericity of coal particles(Q)into the most tightly packed model.As d2 = 0.115×d1/Q in bimodal distribution and d3= d2/(3Q)in trimodal distribution,the results showed that the concentration of CWS become higher.