防治煤自燃的新型稠化胶体特性研究

发布时间：2018-03-08 21:42

本文选题：煤自燃　切入点：稠化胶体　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：注浆是我国煤炭开采行业常用的防灭火措施,针对注浆技术耗水量较大、浆液输送过程常发生堵管的缺点,开发了一种新型稠化胶体材料,该材料能在较低的水固比下对黄土等固相介质实现长期稳定悬浮,并具有剪切稀化特性,利于管路输送。本文通过实验研究和理论分析、计算,对这一新型稠化胶体的特性进行了系统研究,取得了以下研究成果:(1)稠化胶体由天然多糖DG与纤维素醚HD溶于水形成的复配胶体与黄土混合而成,开展了稠化胶体的黄土悬浮特性实验,结果发现:稠化胶体具有最优悬浮能力的临界复配胶体浓度为0.4%,该浓度下稠化胶体能悬浮任意高于1:1水土比条件的黄土,且在pH值接近7.5时具有最佳悬浮性能。稠化胶体能使黄土长期稳定悬浮的原因,一方面是胶体中的DG成分能与Ca2+螯合交联形成三维网状结构,HD成分可起到协同增粘作用,从而将黄土颗粒牢牢束缚在胶体的网状结构中,另一方面DG、HD分子在黄土颗粒表面的吸附,使黄土颗粒间的斥力位能升高,吸力位能下降,以致颗粒的布朗运动不能克服体系的位垒和颗粒间的斥力而聚集。(2)利用流变仪开展了稠化胶体的流变特性实验,结果发现:当天然多糖DG与纤维素醚HD的质量比为5:5时,复配胶体粘度最大,遂将该比例确定为稠化胶体的成胶材料配比;分析复配胶体的流变特性曲线后,确定复配胶体为屈服假塑性流体,在0.4%浓度下其流变本构模型为τ = 0.078 + 2.740γ·0.00427;系统测试了复配胶体的粘弹性,结果表明复配胶体属于粘弹性固体,且趋近于弹性体,较单一的DG胶体具有更宽的线性粘弹区和更强的结构稳定性,其结构一旦受到剪切破坏,在5s内的结构恢复率为43.3%,最终结构恢复率为76.0%;不同水土比的稠化胶体,其剪切应力曲线随剪切速率增长均为先下降后上升,稠化胶体的粘度和屈服应力随黄土比例的升高而升高,水土比为3:1、4:1的稠化胶体流变本构模型依次为τ=25.15 + 2.377γ·0.663、τ = 14.02+ 2.054γ0.583;建立了以连续相粘度和分散相体积分数为参数的稠化胶体粘度预测模型η=10-8.93 58+8.4157Φ+8.6781η0.0051,且预测值与实际值吻合良好;稠化胶体分别在DN100、DN125钢管中以30m3/h的流量流动时,其千米管路压降分别为1.203Mpa、0.778Mpa。(3)开展了稠化胶体防治煤自燃特性实验,结果表明:稠化胶体能使堵漏风测试装置的真空腔体负压维持在-14.6kPa,堵漏风效果优于煤矸石填充和胶带密封;覆盖稠化胶体材料后,隐蔽高温火源中心温度在20s内由446.5℃迅速下降到44.5℃,上方3cm处温度在20s内由185.2℃迅速下降到25.4℃;稠化胶体对煤火的降温能力和降温稳定性均高于黄泥浆,原因是稠化胶体的保水性更好;在煤的氧化升温过程中,稠化胶体处理煤样相比原煤,CO释放量显著降低,交叉点温度提高了 50℃以上,稠化胶体对测试煤样具有良好的阻化效果;常温下稠化胶体处理煤样相对原煤-OH、-COOH含量分别增长了 3%、2.2%,C=O、C-O、取代苯含量则分别降低了 0.6%、1.5%、2.5%,脂肪烃和芳烃C=C变化量在0.2%以内;在煤氧化升温过程中,稠化胶体处理煤样相比原煤,脂肪烃、C-O、C=O、-COOH含量变化速率不同程度的减慢,-OH含量变化速率加快,-COO含量变化速率则无明显改变。
[Abstract]:Grouting is China's coal mining industry commonly used fire prevention measures, the grouting technology consumes large amount of water slurry conveying process often occurs plugging the disadvantages, the development of a new type colloidal gel material, the material in the lower water solid ratio of loess. The solid medium for the long-term stability of suspension, and with shear thinning characteristics, for pipeline transportation. This paper through experimental study and theoretical analysis, calculation, characteristics of this new type of thickening colloid were studied, and the following results are obtained: (1) the dense colloid composed of natural polysaccharides DG and HD cellulose ether soluble in water to form the compound colloid and loess mixture as the suspension experiment, colloidal gel showed that: the critical concentration of colloidal compound thickening colloid has the best suspension capacity is 0.4%, the concentration of colloidal thickening under arbitrary suspension is higher than that of 1:1 ratio in Loess soil, And in the pH value with the best suspension performance is close to 7.5. The dense colloid can make the Loess long steady suspension of reason, one is the DG component in the colloid to form a three-dimensional network structure with Ca2+ chelating HD components, can play a synergistic thickening function, thus the Loess particles bound in the gel network structure on the other hand, DG, HD molecular adsorption on the surface of the Loess loess particles, the interparticle repulsive potential increased, suction potential decreased, so that Brown cannot overcome the barrier of the movement of particles and particle system repulsion and aggregation. (2) the rheological experiment, thickening colloid by rheology instrument results when the DG natural polysaccharide and cellulose ether HD mass ratio was 5:5, the largest proportion of the viscosity of colloidal compound, then determine the proportion of adhesive materials for thickening colloid; rheological properties of colloidal compound curve after determination of colloidal compound To yield pseudoplastic fluid, in 0.4% under the concentration of the rheological constitutive model for R = 0.078 + 2.740 gamma - 0.00427; system test of the viscoelastic colloidal compound, results show that the colloidal compound belongs to viscoelastic solids, and close to the elastic body structure stability than single DG colloid has wider linear viscoelastic and more, the structure when subjected to shear failure, the structure within the 5S recovery rate was 43.3%, the final structure recovery rate was 76%; the dense colloid of different soil ratio, the shear stress curve with the shear rate increase was decreased and then increased, increased thickening gel viscosity and yield stress with the increasing proportion of loess soil, ratio of colloidal gel rheological constitutive model of 3:1,4:1 in =25.15 + 2.377 - gamma tau 0.663, tau = 2.054 14.02+ gamma 0.583; forecast is established by using continuous phase viscosity and volume fraction of dispersed phase parameters of colloidal gel viscosity Model =10-8.93 58+8.4157 +8.6781 ETA Phi ETA 0.0051, and the predicted values are in good agreement with the actual value; the dense colloid respectively in DN100, DN125 pipe to flow 30m3/h, the km pipeline pressure drop were 1.203Mpa, 0.778Mpa. (3) carried out a colloidal gel for prevention of coal spontaneous combustion characteristics of the experiment, the results show that the thickening the colloidal plugging test device of vacuum chamber pressure maintained at -14.6kPa. The plugging effect is better than that of coal gangue filling and sealing tape; covering the dense colloid material, hidden high temperature fire center temperature within 20s from 446.5 DEG C decreased rapidly at 44.5 degrees above the temperature at 3cm in 20s dropped to 25.4 from 185.2 DEG C C; cooling capacity of coal thickening colloid and cooling stability were higher than that of yellow mud, because the water better thickening colloid; in coal oxidation process, dense colloid coal than coal, the release amount of CO Significantly, the junction temperature increased above 50 DEG C, thickening colloid has good effect on the resistance test of coal samples under normal temperature; the dense colloid coal coal relative -OH, -COOH content increased by 3%, 2.2%, C=O, C-O, substituted benzene content were reduced by 0.6%, 1.5%, 2.5%. Fatty hydrocarbon and aromatic hydrocarbon C=C variation was less than 0.2%; in coal oxidation process, dense colloid coal than coal, aliphatic hydrocarbons, C-O, C=O, slow down the rate of change of -COOH content in different degree, the change rate of -OH was accelerated, rate of change of -COO content has no obvious change.

【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD752.2

【参考文献】