煤化工行业氮氧化物排放系数研究

通过现场监测和模拟燃烧实验的方法,分别对陕西某煤化工企业中的甲醇、二甲醚、合成氨和尿素工艺过程中的氮氧化物进行监测,并初步核算各煤化工行业氮氧化物的排放系数.结果显示,不同煤化工行业中,煤炭在作为原料利用时氮氧化物排放量不尽相同,其中甲醇行业氮氧化物排放量为153.19~252.43g/h,平均为211.24g/h;二甲醚行业氮氧化物排放量为22.38~52.20g/h,平均为35.39g/h;合成氨行业为246.48~359.65g/h,平均305.94g/h;尿素行业为13.70~26.75g/h,平均19.89g/h.不同行业氮氧化物的排放系数也有所差别,按照单位产品排放量核算时,各行业氮氧化物的排放系数分别为甲醇41.35~88.10g/t-产品、二甲醚62.27~145.25g/t-产品、合成氨213.47~322.43g/t-产品、尿素0.21~0.41g/t-产品,以单位原料煤消耗量核算出的氮氧化物排放系数分别是甲醇30.18~52.86g/t-原料煤、二甲醚22.83~53.26g/t-原料煤、合成氨119.72~172.73g/t-原料煤、尿素为0.14~0.28g/t-原料煤.通过比较可知,煤在作为原料利用时其氮氧化物的排放系数远小于煤的燃烧过程.     

Experimental research on inhibition performances of the sand-suspended colloid for coal spontaneous combustion

Serious mine fire disasters have occurred in Northwest China where there are abundant coal resources. For the shortage of water and loess, a large cost of conventional grouting slurry is needed. However, plenty of sand and fly ash resources have been found there. In order to improve the quality of sand injection and reduce the wastage of water during grouting, a kind of new compound material of sand-suspended colloid, which is composed of mineral inorganic gel and organic polymer, was developed in this paper. And the inhibition performance experiments of the sand-suspended colloid were carried out. The results show that the sand-suspended colloid efficaciously affected the oxidation characteristics above the critical temperature during the acceleration oxidation of the lignite and fat-gas coal samples and restrained the oxidation course by increasing the activation energy, so that it reduced the contents of CO and C₂H₄ and depressed the oxidation rate during the coal spontaneous combustion, and finally inhibited the coal spontaneous combustion.     

Experimental study on oxygen consumption rate of residual coal in goaf

In order to research the actual oxygen consumption rate of residual coal in goaf, the heating and oxidizing experiment was conducted respectively on five types of single particle size of coal samples and one hybrid particle size of coal samples by using self-developed CSC-B2 test system. This study measured inlet and outlet oxygen concentration of the oxidation tank, and calculated the oxygen consumption rate of each coal sample at different temperatures. For the residual coal in the same goaf, which is regarded as a hybrid particle size of coal consisting of a variety of single granularity of coal, its oxygen consumption rate is the mass weighted average of the rate of each particle size of coal. Accordingly, this paper established the equation of oxygen consumption rate of hybrid particle size of coal samples, taking into account temperature, granularity and oxygen concentration. Then comparison between the calculated value and the actually measured value of oxygen consumption rate of hybrid particle size of coal samples at different temperatures was conducted. And the results reveal that the calculated value basically coincide with the actually measured one. Moreover, the results prove that the established calculation formula for oxygen consumption rate can be used to accurately calculate the actual oxygen consumption rate of residual coal samples. The achievement of this research is of theoretical and practical significance for learning about the characteristics of coal spontaneous combustion and forecasting the self-ignition of residual coal in goaf.     

煤层自燃危险程度的灰色关联分析

将灰色关联分析法应用于煤矿自燃危险程度的评价中,全面考虑影响煤矿生产系统安全的各种因素,结合实例建立了煤矿自燃危险程度的数学模型,阐明了灰色关联分析法的原理和算法,较好地反映了评价过程和评价因素的灰色概念,为制定防范措施和管理决策提供科学依据。     

受压浮煤自燃过程试验研究

矿井采空区遗煤自燃大部分为处于受压状态下的自燃。为观察压力对浮煤自燃过程的影响,采用自制的浮煤加载自燃试验装置对受压浮煤层与自然堆积状态下的自燃过程进行试验研究。结果表明:加载对浮煤的自燃过程确实存在一定影响。加载会加快浮煤层的升温速度,缩短自然发火期,降低最小浮煤层厚度,改变采空区"三带"的划分;加载对厚度介于0.8～1.2 m之间浮煤自燃过程影响最大;随着压力的增加,压力对浮煤自燃过程的影响逐渐减弱,当压力小于1 600 N时,压力的增加对浮煤自燃过程的影响较明显,当压力大于1 600 N时,压力的增加对浮煤自燃过程的影响变小,当压力大于2 600 N时,压力的增加对浮煤自燃过程几乎无影响。     

外墙保温材料数值模拟研究

根据外墙保温材料具体的工程参数为依据,对挤塑型聚苯乙烯(XPS)、膨胀型聚苯乙烯(EPS)和聚氨酯(PU)三种材料的燃烧参数进行设定,设定火源为从窗口喷射而出的火焰,运用FDS软件进行数值模拟与分析。经过模拟发现:外墙保温材料在竖向燃烧中,火焰前锋高度呈现抛物线式增长,y=at2+bt+c,前期增长迅速,后期逐渐平稳。火焰前锋速度按照线性变化,vp=αt+β。在整个燃烧过程中,火焰前锋速度平稳的降低。XPS板导热系数最好,各测点的温度上升最慢,EPS板蓄热系数最好,所以其温度曲线最为平稳。     

高瓦斯沿空留巷采空区自燃危险区域数值模拟

为了掌握高瓦斯沿空留巷采空区遗煤自燃危险区域分布规律,指导工作面防灭火工作。采用数值模拟的方法,以首次采用沿空留巷技术的乌兰矿工作面为实例,模拟分析采空区漏风及氧化带三维分布规律。使用单因素分析法,分别模拟高位钻孔、上隅角埋管及地面钻孔抽采对采空区氧气浓度分布的影响。结果表明:多种瓦斯抽采措施下,工作面及沿空留巷均向采空区漏风,导致氧化带范围扩大,但不同抽采措施导致氧化带扩大的程度不同,高位钻孔抽采最弱,上隅角瓦斯抽采次之,地面钻孔抽采最强。沿空留巷附近及上覆采空区供氧时间长,自然发火危险性高。     

煤自燃发火潜伏期不同温度下耗氧特性的研究

为了探究地层温度的升高对采空区自燃倾向性的影响,对处于自燃潜伏期的煤展开耗氧特性和CO释放特性的研究。通过对长平矿3#煤分别进行20~60℃的封闭耗氧实验,得到了自燃潜伏期不同温度下煤的氧浓度以及CO浓度随时间变化的曲线。对氧浓度变化曲线和CO浓度变化曲线进行拟合分析得到了不同温度下煤的氧气消耗和CO生成速度,同时得到了氧浓度衰减系数和CO浓度增长系数。封闭耗氧实验结果表明:从20~60℃氧气消耗速度逐渐增大并且氧浓度衰减系数呈指数增长,CO浓度增长系数也逐渐增大并且同样呈指数增长,煤的窒熄带氧浓度临界值从20~60℃逐渐由16.8%降低到12.4%。为探究不同温度下采空区煤的自燃发火危险性,将封闭耗氧实验结果的参数应用到采空区CFD数值模拟仿真中,模拟得到随着温度升高采空区窒熄带临界氧浓度位置由200 m增长到380 m。结果表明:常温下不易自燃的煤在较高的环境温度下表现出了较强的氧气消耗和CO释放能力,并且采空区自然氧化带随着温度的升高动态变宽,增大了采空区的自燃发火危险性。     

矿用无机固化泡沫充填材料研究及应用

针对井下堵漏风和密闭墙构建时存在的劳动强度大,密封效果差等缺点,研制了一种无机固化泡沫充填材料,通过大量的实验研究了泡沫掺量、水灰比和胶凝剂对材料性能的影响,并对其进行了现场应用。研究结果表明:泡沫掺量的增加和水灰比的增大均能使初凝时间增加,硫铝酸盐水泥充填材料的初凝时间是普通水泥充填材料的31%～44%;抗压强度随泡沫掺量增加而明显降低,硫铝酸盐水泥为胶凝剂时的充填材料抗压强度较大;泡沫掺量为1,2,3倍时的材料密度是未添加泡沫时的40%～46%,23%～33%和18%～24%,可以显著降低劳动强度;硫铝酸盐充填材料在内部孔结构方面优于普通水泥充填材料。研究成果可用于确定最佳的无机固化泡沫充填材料配方,现场应用表明材料密封效果和抗压强度好,具有广阔的应用空间。     

点火提前角对焦炉气天然气混燃发动机燃烧特性的影响分析

为了研究不同点火提前角对焦炉气与天然气混燃发动机燃烧特性的影响,对一台6缸焦炉气发动机,运用CATIA建立其燃烧室模型。在相同的条件下,运用CFD分析软件研究了6种点火提前角（θig）下焦炉气与天然气发动机的燃烧特性。模拟表明:随着θig的提前,缸内的压力、温度、NO生成量的峰值都会升高且提前,当θig推迟到-12 ℃A以后时,出现严重的后燃现象,使得排放温度升高;当θig提前到-25 ℃A之前时,NO的生成量和缸内流速迅速增加,快速燃烧在压缩上止点之前10 ℃A范围内,发动机做负功;当θig为-15 ℃A时,虽然NO的生成有所增加,但是增加的不是很大,并且压力、温度、快速燃烧都在做功行程接近上止点的位置。