燃煤渣花岗岩粉基地质聚合物的制备

采用燃煤渣和花岗岩粉为主要原料制备地质聚合物。结果表明,当燃煤渣与花岗岩粉的质量比为10,NaOH溶液(6 mol/L)与燃煤渣比值为0.25 mL/g,水玻璃与燃煤渣比值为0.18 mL/g,养护温度60℃,带模养护时间2天时,脱模后得到的最终产物在28天的抗压强度可达20.96 MPa。氢氧化钠溶液对试样抗压强度的影响是硅铝溶解、泛霜及孔隙率变化等多重因素综合作用的结果。水玻璃的加入并不能使试样的矿物组成发生较大改变,但可以显著提高反应体系中硅酸盐低聚离子的浓度,增加凝胶的生成量。花岗岩粉在碱激发的条件下未表现出明显的地质聚合能力,但适量掺入仍可以起到骨料和填充作用,提高地质聚合物的抗压强度。本研究拓宽了制备地质聚合物的原料来源,为燃煤渣和花岗岩粉在建筑材料方面的利用提供了参考。

燃煤渣和花岗岩石粉协同制备地聚合物研究

为实现燃煤渣和花岗岩石粉综合利用,以燃煤渣为主要原料,花岗岩石粉作为辅料,氧化钙、磷酸钠和水玻璃为碱激发剂制备地聚合物。结果表明,地聚合物最佳制备条件为:燃煤渣与花岗岩石粉的质量比为90∶10,氧化钙、磷酸钠和水玻璃用量分别为20%、5%和15%。此条件下地聚合物28 d抗压强度达35.45 MPa。采用X射线衍射(XRD)仪和扫描电镜(SEM)对地聚合物进行分析,结果表明,复配激发剂加速了燃煤渣的溶解,形成的复杂凝胶相显著提高了地聚合物的抗压强度,同时,掺入花岗岩石粉有利于改善浆体流动性,使地聚合物微观结构更致密。

高钙煤气化渣和燃烧渣对模拟废水中Pb^(2+) 的脱除作用对比研究

以高钙煤气化渣和煤燃烧渣为原料开展对Pb^(2+)脱除的对比实验研究,考察了接触时间(0 h~72 h)、灰渣投加量(0.05 g~0.20 g)、Pb^(2+)溶液初始pH值(2.5~6.0)对Pb^(2+)脱除的影响,分析了钙元素在Pb^(2+)脱除过程中的作用,并对比分析了两类灰渣的脱除机制。结果表明:Pb^(2+)初始质量浓度为100 mg/L、模拟废水体积为50 mL、接触时间为24 h、灰渣投加量为0.20 g、Pb^(2+)溶液初始pH值为5时,灰渣对Pb^(2+)脱除效果最优,燃煤渣和气化渣对Pb^(2+)的脱除率分别高达94.5%和99.5%;燃煤渣脱除Pb^(2+)的过程包括灰渣水解产OH-,析出Pb(OH)_(2)晶粒,吸收空气中CO_(2)转变为碱式碳酸铅[Pb_(3)(CO_(3))_(2)(OH)_(2)]并最终絮凝沉淀三个阶段,属于化学沉淀作用;气化渣脱除Pb^(2+)的过程除了化学沉淀作用外,灰渣中多孔残碳颗粒的物理吸附也起到了促进作用。高钙灰渣应用于重金属污染废水的治理是实现其资源化、增值化利用的有效途径之一。

Type Selection of Burning Equipment for Slagging-Coal Boilers

The type selection of burning equipment for boilers is affected significantly by the slagging characteristics of coal. Based on the engineering statistics method, the designed furnace parameters are obtained from the 600-MW and 1 000-MW boilers with tangential firing and wall firing. The power and arrangement of the burners are analyzed. Their impacts on slagging on heating surfaces and the carbon contents in the ash and cinders are also discussed. Thermal parameters of furnace are recommended for boilers of 600 MW and 1 000 MW firing slagging coal in the design. The static or rotary classifier should be the first choice for the pulverizing system.

Slagging characteristics of molten coal ash on silicon-aluminum combustion liners of boiler

In order to study the slagging characteristics of boiler combustion liners during pulverized coal stream combustion, the slag samples on the surface of combustion liner were investigated by X-ray diffractometry, scan electron microscopy and energy dispersive X-ray analysis, and the transformation characteristics of the compositions and crystal phases were studied. The results show that the size of slag granules decreases as the slagging temperature increases; the crystallinity of coal ash I reduces to about 48.6% when the temperature is increased up to 1 350 ℃, and that of the coal ash II reduces to about 65% when the temperature is increased up to 1 500 ℃; the encroachment of molten coal ash to the combustion liner is strengthened. At the same time, the diffusion and the segregation of the compositions in combustion liners have selectivity, which is in favor of enhancing the content of crystal phases, weakening the conglutination among molten slag compositions and combustion liner, and avoiding yielding big clinkers. But the diffusion of the compositions in combustion liners increases the porosity and decreases the mechanical intensity of combustion liner, and makes the slag encroachment to the liner become more serious.